linux/net/core/skbuff.c
<<
>>
Prefs
   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 *      Routines having to do with the 'struct sk_buff' memory handlers.
   4 *
   5 *      Authors:        Alan Cox <alan@lxorguk.ukuu.org.uk>
   6 *                      Florian La Roche <rzsfl@rz.uni-sb.de>
   7 *
   8 *      Fixes:
   9 *              Alan Cox        :       Fixed the worst of the load
  10 *                                      balancer bugs.
  11 *              Dave Platt      :       Interrupt stacking fix.
  12 *      Richard Kooijman        :       Timestamp fixes.
  13 *              Alan Cox        :       Changed buffer format.
  14 *              Alan Cox        :       destructor hook for AF_UNIX etc.
  15 *              Linus Torvalds  :       Better skb_clone.
  16 *              Alan Cox        :       Added skb_copy.
  17 *              Alan Cox        :       Added all the changed routines Linus
  18 *                                      only put in the headers
  19 *              Ray VanTassle   :       Fixed --skb->lock in free
  20 *              Alan Cox        :       skb_copy copy arp field
  21 *              Andi Kleen      :       slabified it.
  22 *              Robert Olsson   :       Removed skb_head_pool
  23 *
  24 *      NOTE:
  25 *              The __skb_ routines should be called with interrupts
  26 *      disabled, or you better be *real* sure that the operation is atomic
  27 *      with respect to whatever list is being frobbed (e.g. via lock_sock()
  28 *      or via disabling bottom half handlers, etc).
  29 */
  30
  31/*
  32 *      The functions in this file will not compile correctly with gcc 2.4.x
  33 */
  34
  35#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  36
  37#include <linux/module.h>
  38#include <linux/types.h>
  39#include <linux/kernel.h>
  40#include <linux/mm.h>
  41#include <linux/interrupt.h>
  42#include <linux/in.h>
  43#include <linux/inet.h>
  44#include <linux/slab.h>
  45#include <linux/tcp.h>
  46#include <linux/udp.h>
  47#include <linux/sctp.h>
  48#include <linux/netdevice.h>
  49#ifdef CONFIG_NET_CLS_ACT
  50#include <net/pkt_sched.h>
  51#endif
  52#include <linux/string.h>
  53#include <linux/skbuff.h>
  54#include <linux/splice.h>
  55#include <linux/cache.h>
  56#include <linux/rtnetlink.h>
  57#include <linux/init.h>
  58#include <linux/scatterlist.h>
  59#include <linux/errqueue.h>
  60#include <linux/prefetch.h>
  61#include <linux/if_vlan.h>
  62#include <linux/mpls.h>
  63#include <linux/kcov.h>
  64
  65#include <net/protocol.h>
  66#include <net/dst.h>
  67#include <net/sock.h>
  68#include <net/checksum.h>
  69#include <net/ip6_checksum.h>
  70#include <net/xfrm.h>
  71#include <net/mpls.h>
  72#include <net/mptcp.h>
  73#include <net/page_pool.h>
  74
  75#include <linux/uaccess.h>
  76#include <trace/events/skb.h>
  77#include <linux/highmem.h>
  78#include <linux/capability.h>
  79#include <linux/user_namespace.h>
  80#include <linux/indirect_call_wrapper.h>
  81
  82#include "datagram.h"
  83
  84struct kmem_cache *skbuff_head_cache __ro_after_init;
  85static struct kmem_cache *skbuff_fclone_cache __ro_after_init;
  86#ifdef CONFIG_SKB_EXTENSIONS
  87static struct kmem_cache *skbuff_ext_cache __ro_after_init;
  88#endif
  89int sysctl_max_skb_frags __read_mostly = MAX_SKB_FRAGS;
  90EXPORT_SYMBOL(sysctl_max_skb_frags);
  91
  92/**
  93 *      skb_panic - private function for out-of-line support
  94 *      @skb:   buffer
  95 *      @sz:    size
  96 *      @addr:  address
  97 *      @msg:   skb_over_panic or skb_under_panic
  98 *
  99 *      Out-of-line support for skb_put() and skb_push().
 100 *      Called via the wrapper skb_over_panic() or skb_under_panic().
 101 *      Keep out of line to prevent kernel bloat.
 102 *      __builtin_return_address is not used because it is not always reliable.
 103 */
 104static void skb_panic(struct sk_buff *skb, unsigned int sz, void *addr,
 105                      const char msg[])
 106{
 107        pr_emerg("%s: text:%px len:%d put:%d head:%px data:%px tail:%#lx end:%#lx dev:%s\n",
 108                 msg, addr, skb->len, sz, skb->head, skb->data,
 109                 (unsigned long)skb->tail, (unsigned long)skb->end,
 110                 skb->dev ? skb->dev->name : "<NULL>");
 111        BUG();
 112}
 113
 114static void skb_over_panic(struct sk_buff *skb, unsigned int sz, void *addr)
 115{
 116        skb_panic(skb, sz, addr, __func__);
 117}
 118
 119static void skb_under_panic(struct sk_buff *skb, unsigned int sz, void *addr)
 120{
 121        skb_panic(skb, sz, addr, __func__);
 122}
 123
 124#define NAPI_SKB_CACHE_SIZE     64
 125#define NAPI_SKB_CACHE_BULK     16
 126#define NAPI_SKB_CACHE_HALF     (NAPI_SKB_CACHE_SIZE / 2)
 127
 128struct napi_alloc_cache {
 129        struct page_frag_cache page;
 130        unsigned int skb_count;
 131        void *skb_cache[NAPI_SKB_CACHE_SIZE];
 132};
 133
 134static DEFINE_PER_CPU(struct page_frag_cache, netdev_alloc_cache);
 135static DEFINE_PER_CPU(struct napi_alloc_cache, napi_alloc_cache);
 136
 137static void *__alloc_frag_align(unsigned int fragsz, gfp_t gfp_mask,
 138                                unsigned int align_mask)
 139{
 140        struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
 141
 142        return page_frag_alloc_align(&nc->page, fragsz, gfp_mask, align_mask);
 143}
 144
 145void *__napi_alloc_frag_align(unsigned int fragsz, unsigned int align_mask)
 146{
 147        fragsz = SKB_DATA_ALIGN(fragsz);
 148
 149        return __alloc_frag_align(fragsz, GFP_ATOMIC, align_mask);
 150}
 151EXPORT_SYMBOL(__napi_alloc_frag_align);
 152
 153void *__netdev_alloc_frag_align(unsigned int fragsz, unsigned int align_mask)
 154{
 155        struct page_frag_cache *nc;
 156        void *data;
 157
 158        fragsz = SKB_DATA_ALIGN(fragsz);
 159        if (in_irq() || irqs_disabled()) {
 160                nc = this_cpu_ptr(&netdev_alloc_cache);
 161                data = page_frag_alloc_align(nc, fragsz, GFP_ATOMIC, align_mask);
 162        } else {
 163                local_bh_disable();
 164                data = __alloc_frag_align(fragsz, GFP_ATOMIC, align_mask);
 165                local_bh_enable();
 166        }
 167        return data;
 168}
 169EXPORT_SYMBOL(__netdev_alloc_frag_align);
 170
 171static struct sk_buff *napi_skb_cache_get(void)
 172{
 173        struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
 174        struct sk_buff *skb;
 175
 176        if (unlikely(!nc->skb_count))
 177                nc->skb_count = kmem_cache_alloc_bulk(skbuff_head_cache,
 178                                                      GFP_ATOMIC,
 179                                                      NAPI_SKB_CACHE_BULK,
 180                                                      nc->skb_cache);
 181        if (unlikely(!nc->skb_count))
 182                return NULL;
 183
 184        skb = nc->skb_cache[--nc->skb_count];
 185        kasan_unpoison_object_data(skbuff_head_cache, skb);
 186
 187        return skb;
 188}
 189
 190/* Caller must provide SKB that is memset cleared */
 191static void __build_skb_around(struct sk_buff *skb, void *data,
 192                               unsigned int frag_size)
 193{
 194        struct skb_shared_info *shinfo;
 195        unsigned int size = frag_size ? : ksize(data);
 196
 197        size -= SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 198
 199        /* Assumes caller memset cleared SKB */
 200        skb->truesize = SKB_TRUESIZE(size);
 201        refcount_set(&skb->users, 1);
 202        skb->head = data;
 203        skb->data = data;
 204        skb_reset_tail_pointer(skb);
 205        skb->end = skb->tail + size;
 206        skb->mac_header = (typeof(skb->mac_header))~0U;
 207        skb->transport_header = (typeof(skb->transport_header))~0U;
 208
 209        /* make sure we initialize shinfo sequentially */
 210        shinfo = skb_shinfo(skb);
 211        memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
 212        atomic_set(&shinfo->dataref, 1);
 213
 214        skb_set_kcov_handle(skb, kcov_common_handle());
 215}
 216
 217/**
 218 * __build_skb - build a network buffer
 219 * @data: data buffer provided by caller
 220 * @frag_size: size of data, or 0 if head was kmalloced
 221 *
 222 * Allocate a new &sk_buff. Caller provides space holding head and
 223 * skb_shared_info. @data must have been allocated by kmalloc() only if
 224 * @frag_size is 0, otherwise data should come from the page allocator
 225 *  or vmalloc()
 226 * The return is the new skb buffer.
 227 * On a failure the return is %NULL, and @data is not freed.
 228 * Notes :
 229 *  Before IO, driver allocates only data buffer where NIC put incoming frame
 230 *  Driver should add room at head (NET_SKB_PAD) and
 231 *  MUST add room at tail (SKB_DATA_ALIGN(skb_shared_info))
 232 *  After IO, driver calls build_skb(), to allocate sk_buff and populate it
 233 *  before giving packet to stack.
 234 *  RX rings only contains data buffers, not full skbs.
 235 */
 236struct sk_buff *__build_skb(void *data, unsigned int frag_size)
 237{
 238        struct sk_buff *skb;
 239
 240        skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
 241        if (unlikely(!skb))
 242                return NULL;
 243
 244        memset(skb, 0, offsetof(struct sk_buff, tail));
 245        __build_skb_around(skb, data, frag_size);
 246
 247        return skb;
 248}
 249
 250/* build_skb() is wrapper over __build_skb(), that specifically
 251 * takes care of skb->head and skb->pfmemalloc
 252 * This means that if @frag_size is not zero, then @data must be backed
 253 * by a page fragment, not kmalloc() or vmalloc()
 254 */
 255struct sk_buff *build_skb(void *data, unsigned int frag_size)
 256{
 257        struct sk_buff *skb = __build_skb(data, frag_size);
 258
 259        if (skb && frag_size) {
 260                skb->head_frag = 1;
 261                if (page_is_pfmemalloc(virt_to_head_page(data)))
 262                        skb->pfmemalloc = 1;
 263        }
 264        return skb;
 265}
 266EXPORT_SYMBOL(build_skb);
 267
 268/**
 269 * build_skb_around - build a network buffer around provided skb
 270 * @skb: sk_buff provide by caller, must be memset cleared
 271 * @data: data buffer provided by caller
 272 * @frag_size: size of data, or 0 if head was kmalloced
 273 */
 274struct sk_buff *build_skb_around(struct sk_buff *skb,
 275                                 void *data, unsigned int frag_size)
 276{
 277        if (unlikely(!skb))
 278                return NULL;
 279
 280        __build_skb_around(skb, data, frag_size);
 281
 282        if (frag_size) {
 283                skb->head_frag = 1;
 284                if (page_is_pfmemalloc(virt_to_head_page(data)))
 285                        skb->pfmemalloc = 1;
 286        }
 287        return skb;
 288}
 289EXPORT_SYMBOL(build_skb_around);
 290
 291/**
 292 * __napi_build_skb - build a network buffer
 293 * @data: data buffer provided by caller
 294 * @frag_size: size of data, or 0 if head was kmalloced
 295 *
 296 * Version of __build_skb() that uses NAPI percpu caches to obtain
 297 * skbuff_head instead of inplace allocation.
 298 *
 299 * Returns a new &sk_buff on success, %NULL on allocation failure.
 300 */
 301static struct sk_buff *__napi_build_skb(void *data, unsigned int frag_size)
 302{
 303        struct sk_buff *skb;
 304
 305        skb = napi_skb_cache_get();
 306        if (unlikely(!skb))
 307                return NULL;
 308
 309        memset(skb, 0, offsetof(struct sk_buff, tail));
 310        __build_skb_around(skb, data, frag_size);
 311
 312        return skb;
 313}
 314
 315/**
 316 * napi_build_skb - build a network buffer
 317 * @data: data buffer provided by caller
 318 * @frag_size: size of data, or 0 if head was kmalloced
 319 *
 320 * Version of __napi_build_skb() that takes care of skb->head_frag
 321 * and skb->pfmemalloc when the data is a page or page fragment.
 322 *
 323 * Returns a new &sk_buff on success, %NULL on allocation failure.
 324 */
 325struct sk_buff *napi_build_skb(void *data, unsigned int frag_size)
 326{
 327        struct sk_buff *skb = __napi_build_skb(data, frag_size);
 328
 329        if (likely(skb) && frag_size) {
 330                skb->head_frag = 1;
 331                skb_propagate_pfmemalloc(virt_to_head_page(data), skb);
 332        }
 333
 334        return skb;
 335}
 336EXPORT_SYMBOL(napi_build_skb);
 337
 338/*
 339 * kmalloc_reserve is a wrapper around kmalloc_node_track_caller that tells
 340 * the caller if emergency pfmemalloc reserves are being used. If it is and
 341 * the socket is later found to be SOCK_MEMALLOC then PFMEMALLOC reserves
 342 * may be used. Otherwise, the packet data may be discarded until enough
 343 * memory is free
 344 */
 345static void *kmalloc_reserve(size_t size, gfp_t flags, int node,
 346                             bool *pfmemalloc)
 347{
 348        void *obj;
 349        bool ret_pfmemalloc = false;
 350
 351        /*
 352         * Try a regular allocation, when that fails and we're not entitled
 353         * to the reserves, fail.
 354         */
 355        obj = kmalloc_node_track_caller(size,
 356                                        flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
 357                                        node);
 358        if (obj || !(gfp_pfmemalloc_allowed(flags)))
 359                goto out;
 360
 361        /* Try again but now we are using pfmemalloc reserves */
 362        ret_pfmemalloc = true;
 363        obj = kmalloc_node_track_caller(size, flags, node);
 364
 365out:
 366        if (pfmemalloc)
 367                *pfmemalloc = ret_pfmemalloc;
 368
 369        return obj;
 370}
 371
 372/*      Allocate a new skbuff. We do this ourselves so we can fill in a few
 373 *      'private' fields and also do memory statistics to find all the
 374 *      [BEEP] leaks.
 375 *
 376 */
 377
 378/**
 379 *      __alloc_skb     -       allocate a network buffer
 380 *      @size: size to allocate
 381 *      @gfp_mask: allocation mask
 382 *      @flags: If SKB_ALLOC_FCLONE is set, allocate from fclone cache
 383 *              instead of head cache and allocate a cloned (child) skb.
 384 *              If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for
 385 *              allocations in case the data is required for writeback
 386 *      @node: numa node to allocate memory on
 387 *
 388 *      Allocate a new &sk_buff. The returned buffer has no headroom and a
 389 *      tail room of at least size bytes. The object has a reference count
 390 *      of one. The return is the buffer. On a failure the return is %NULL.
 391 *
 392 *      Buffers may only be allocated from interrupts using a @gfp_mask of
 393 *      %GFP_ATOMIC.
 394 */
 395struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
 396                            int flags, int node)
 397{
 398        struct kmem_cache *cache;
 399        struct sk_buff *skb;
 400        u8 *data;
 401        bool pfmemalloc;
 402
 403        cache = (flags & SKB_ALLOC_FCLONE)
 404                ? skbuff_fclone_cache : skbuff_head_cache;
 405
 406        if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX))
 407                gfp_mask |= __GFP_MEMALLOC;
 408
 409        /* Get the HEAD */
 410        if ((flags & (SKB_ALLOC_FCLONE | SKB_ALLOC_NAPI)) == SKB_ALLOC_NAPI &&
 411            likely(node == NUMA_NO_NODE || node == numa_mem_id()))
 412                skb = napi_skb_cache_get();
 413        else
 414                skb = kmem_cache_alloc_node(cache, gfp_mask & ~GFP_DMA, node);
 415        if (unlikely(!skb))
 416                return NULL;
 417        prefetchw(skb);
 418
 419        /* We do our best to align skb_shared_info on a separate cache
 420         * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
 421         * aligned memory blocks, unless SLUB/SLAB debug is enabled.
 422         * Both skb->head and skb_shared_info are cache line aligned.
 423         */
 424        size = SKB_DATA_ALIGN(size);
 425        size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 426        data = kmalloc_reserve(size, gfp_mask, node, &pfmemalloc);
 427        if (unlikely(!data))
 428                goto nodata;
 429        /* kmalloc(size) might give us more room than requested.
 430         * Put skb_shared_info exactly at the end of allocated zone,
 431         * to allow max possible filling before reallocation.
 432         */
 433        size = SKB_WITH_OVERHEAD(ksize(data));
 434        prefetchw(data + size);
 435
 436        /*
 437         * Only clear those fields we need to clear, not those that we will
 438         * actually initialise below. Hence, don't put any more fields after
 439         * the tail pointer in struct sk_buff!
 440         */
 441        memset(skb, 0, offsetof(struct sk_buff, tail));
 442        __build_skb_around(skb, data, 0);
 443        skb->pfmemalloc = pfmemalloc;
 444
 445        if (flags & SKB_ALLOC_FCLONE) {
 446                struct sk_buff_fclones *fclones;
 447
 448                fclones = container_of(skb, struct sk_buff_fclones, skb1);
 449
 450                skb->fclone = SKB_FCLONE_ORIG;
 451                refcount_set(&fclones->fclone_ref, 1);
 452
 453                fclones->skb2.fclone = SKB_FCLONE_CLONE;
 454        }
 455
 456        return skb;
 457
 458nodata:
 459        kmem_cache_free(cache, skb);
 460        return NULL;
 461}
 462EXPORT_SYMBOL(__alloc_skb);
 463
 464/**
 465 *      __netdev_alloc_skb - allocate an skbuff for rx on a specific device
 466 *      @dev: network device to receive on
 467 *      @len: length to allocate
 468 *      @gfp_mask: get_free_pages mask, passed to alloc_skb
 469 *
 470 *      Allocate a new &sk_buff and assign it a usage count of one. The
 471 *      buffer has NET_SKB_PAD headroom built in. Users should allocate
 472 *      the headroom they think they need without accounting for the
 473 *      built in space. The built in space is used for optimisations.
 474 *
 475 *      %NULL is returned if there is no free memory.
 476 */
 477struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int len,
 478                                   gfp_t gfp_mask)
 479{
 480        struct page_frag_cache *nc;
 481        struct sk_buff *skb;
 482        bool pfmemalloc;
 483        void *data;
 484
 485        len += NET_SKB_PAD;
 486
 487        /* If requested length is either too small or too big,
 488         * we use kmalloc() for skb->head allocation.
 489         */
 490        if (len <= SKB_WITH_OVERHEAD(1024) ||
 491            len > SKB_WITH_OVERHEAD(PAGE_SIZE) ||
 492            (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
 493                skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, NUMA_NO_NODE);
 494                if (!skb)
 495                        goto skb_fail;
 496                goto skb_success;
 497        }
 498
 499        len += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 500        len = SKB_DATA_ALIGN(len);
 501
 502        if (sk_memalloc_socks())
 503                gfp_mask |= __GFP_MEMALLOC;
 504
 505        if (in_irq() || irqs_disabled()) {
 506                nc = this_cpu_ptr(&netdev_alloc_cache);
 507                data = page_frag_alloc(nc, len, gfp_mask);
 508                pfmemalloc = nc->pfmemalloc;
 509        } else {
 510                local_bh_disable();
 511                nc = this_cpu_ptr(&napi_alloc_cache.page);
 512                data = page_frag_alloc(nc, len, gfp_mask);
 513                pfmemalloc = nc->pfmemalloc;
 514                local_bh_enable();
 515        }
 516
 517        if (unlikely(!data))
 518                return NULL;
 519
 520        skb = __build_skb(data, len);
 521        if (unlikely(!skb)) {
 522                skb_free_frag(data);
 523                return NULL;
 524        }
 525
 526        if (pfmemalloc)
 527                skb->pfmemalloc = 1;
 528        skb->head_frag = 1;
 529
 530skb_success:
 531        skb_reserve(skb, NET_SKB_PAD);
 532        skb->dev = dev;
 533
 534skb_fail:
 535        return skb;
 536}
 537EXPORT_SYMBOL(__netdev_alloc_skb);
 538
 539/**
 540 *      __napi_alloc_skb - allocate skbuff for rx in a specific NAPI instance
 541 *      @napi: napi instance this buffer was allocated for
 542 *      @len: length to allocate
 543 *      @gfp_mask: get_free_pages mask, passed to alloc_skb and alloc_pages
 544 *
 545 *      Allocate a new sk_buff for use in NAPI receive.  This buffer will
 546 *      attempt to allocate the head from a special reserved region used
 547 *      only for NAPI Rx allocation.  By doing this we can save several
 548 *      CPU cycles by avoiding having to disable and re-enable IRQs.
 549 *
 550 *      %NULL is returned if there is no free memory.
 551 */
 552struct sk_buff *__napi_alloc_skb(struct napi_struct *napi, unsigned int len,
 553                                 gfp_t gfp_mask)
 554{
 555        struct napi_alloc_cache *nc;
 556        struct sk_buff *skb;
 557        void *data;
 558
 559        len += NET_SKB_PAD + NET_IP_ALIGN;
 560
 561        /* If requested length is either too small or too big,
 562         * we use kmalloc() for skb->head allocation.
 563         */
 564        if (len <= SKB_WITH_OVERHEAD(1024) ||
 565            len > SKB_WITH_OVERHEAD(PAGE_SIZE) ||
 566            (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
 567                skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX | SKB_ALLOC_NAPI,
 568                                  NUMA_NO_NODE);
 569                if (!skb)
 570                        goto skb_fail;
 571                goto skb_success;
 572        }
 573
 574        nc = this_cpu_ptr(&napi_alloc_cache);
 575        len += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 576        len = SKB_DATA_ALIGN(len);
 577
 578        if (sk_memalloc_socks())
 579                gfp_mask |= __GFP_MEMALLOC;
 580
 581        data = page_frag_alloc(&nc->page, len, gfp_mask);
 582        if (unlikely(!data))
 583                return NULL;
 584
 585        skb = __napi_build_skb(data, len);
 586        if (unlikely(!skb)) {
 587                skb_free_frag(data);
 588                return NULL;
 589        }
 590
 591        if (nc->page.pfmemalloc)
 592                skb->pfmemalloc = 1;
 593        skb->head_frag = 1;
 594
 595skb_success:
 596        skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
 597        skb->dev = napi->dev;
 598
 599skb_fail:
 600        return skb;
 601}
 602EXPORT_SYMBOL(__napi_alloc_skb);
 603
 604void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
 605                     int size, unsigned int truesize)
 606{
 607        skb_fill_page_desc(skb, i, page, off, size);
 608        skb->len += size;
 609        skb->data_len += size;
 610        skb->truesize += truesize;
 611}
 612EXPORT_SYMBOL(skb_add_rx_frag);
 613
 614void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
 615                          unsigned int truesize)
 616{
 617        skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 618
 619        skb_frag_size_add(frag, size);
 620        skb->len += size;
 621        skb->data_len += size;
 622        skb->truesize += truesize;
 623}
 624EXPORT_SYMBOL(skb_coalesce_rx_frag);
 625
 626static void skb_drop_list(struct sk_buff **listp)
 627{
 628        kfree_skb_list(*listp);
 629        *listp = NULL;
 630}
 631
 632static inline void skb_drop_fraglist(struct sk_buff *skb)
 633{
 634        skb_drop_list(&skb_shinfo(skb)->frag_list);
 635}
 636
 637static void skb_clone_fraglist(struct sk_buff *skb)
 638{
 639        struct sk_buff *list;
 640
 641        skb_walk_frags(skb, list)
 642                skb_get(list);
 643}
 644
 645static void skb_free_head(struct sk_buff *skb)
 646{
 647        unsigned char *head = skb->head;
 648
 649        if (skb->head_frag) {
 650                if (skb_pp_recycle(skb, head))
 651                        return;
 652                skb_free_frag(head);
 653        } else {
 654                kfree(head);
 655        }
 656}
 657
 658static void skb_release_data(struct sk_buff *skb)
 659{
 660        struct skb_shared_info *shinfo = skb_shinfo(skb);
 661        int i;
 662
 663        if (skb->cloned &&
 664            atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
 665                              &shinfo->dataref))
 666                goto exit;
 667
 668        skb_zcopy_clear(skb, true);
 669
 670        for (i = 0; i < shinfo->nr_frags; i++)
 671                __skb_frag_unref(&shinfo->frags[i], skb->pp_recycle);
 672
 673        if (shinfo->frag_list)
 674                kfree_skb_list(shinfo->frag_list);
 675
 676        skb_free_head(skb);
 677exit:
 678        /* When we clone an SKB we copy the reycling bit. The pp_recycle
 679         * bit is only set on the head though, so in order to avoid races
 680         * while trying to recycle fragments on __skb_frag_unref() we need
 681         * to make one SKB responsible for triggering the recycle path.
 682         * So disable the recycling bit if an SKB is cloned and we have
 683         * additional references to to the fragmented part of the SKB.
 684         * Eventually the last SKB will have the recycling bit set and it's
 685         * dataref set to 0, which will trigger the recycling
 686         */
 687        skb->pp_recycle = 0;
 688}
 689
 690/*
 691 *      Free an skbuff by memory without cleaning the state.
 692 */
 693static void kfree_skbmem(struct sk_buff *skb)
 694{
 695        struct sk_buff_fclones *fclones;
 696
 697        switch (skb->fclone) {
 698        case SKB_FCLONE_UNAVAILABLE:
 699                kmem_cache_free(skbuff_head_cache, skb);
 700                return;
 701
 702        case SKB_FCLONE_ORIG:
 703                fclones = container_of(skb, struct sk_buff_fclones, skb1);
 704
 705                /* We usually free the clone (TX completion) before original skb
 706                 * This test would have no chance to be true for the clone,
 707                 * while here, branch prediction will be good.
 708                 */
 709                if (refcount_read(&fclones->fclone_ref) == 1)
 710                        goto fastpath;
 711                break;
 712
 713        default: /* SKB_FCLONE_CLONE */
 714                fclones = container_of(skb, struct sk_buff_fclones, skb2);
 715                break;
 716        }
 717        if (!refcount_dec_and_test(&fclones->fclone_ref))
 718                return;
 719fastpath:
 720        kmem_cache_free(skbuff_fclone_cache, fclones);
 721}
 722
 723void skb_release_head_state(struct sk_buff *skb)
 724{
 725        skb_dst_drop(skb);
 726        if (skb->destructor) {
 727                WARN_ON(in_irq());
 728                skb->destructor(skb);
 729        }
 730#if IS_ENABLED(CONFIG_NF_CONNTRACK)
 731        nf_conntrack_put(skb_nfct(skb));
 732#endif
 733        skb_ext_put(skb);
 734}
 735
 736/* Free everything but the sk_buff shell. */
 737static void skb_release_all(struct sk_buff *skb)
 738{
 739        skb_release_head_state(skb);
 740        if (likely(skb->head))
 741                skb_release_data(skb);
 742}
 743
 744/**
 745 *      __kfree_skb - private function
 746 *      @skb: buffer
 747 *
 748 *      Free an sk_buff. Release anything attached to the buffer.
 749 *      Clean the state. This is an internal helper function. Users should
 750 *      always call kfree_skb
 751 */
 752
 753void __kfree_skb(struct sk_buff *skb)
 754{
 755        skb_release_all(skb);
 756        kfree_skbmem(skb);
 757}
 758EXPORT_SYMBOL(__kfree_skb);
 759
 760/**
 761 *      kfree_skb - free an sk_buff
 762 *      @skb: buffer to free
 763 *
 764 *      Drop a reference to the buffer and free it if the usage count has
 765 *      hit zero.
 766 */
 767void kfree_skb(struct sk_buff *skb)
 768{
 769        if (!skb_unref(skb))
 770                return;
 771
 772        trace_kfree_skb(skb, __builtin_return_address(0));
 773        __kfree_skb(skb);
 774}
 775EXPORT_SYMBOL(kfree_skb);
 776
 777void kfree_skb_list(struct sk_buff *segs)
 778{
 779        while (segs) {
 780                struct sk_buff *next = segs->next;
 781
 782                kfree_skb(segs);
 783                segs = next;
 784        }
 785}
 786EXPORT_SYMBOL(kfree_skb_list);
 787
 788/* Dump skb information and contents.
 789 *
 790 * Must only be called from net_ratelimit()-ed paths.
 791 *
 792 * Dumps whole packets if full_pkt, only headers otherwise.
 793 */
 794void skb_dump(const char *level, const struct sk_buff *skb, bool full_pkt)
 795{
 796        struct skb_shared_info *sh = skb_shinfo(skb);
 797        struct net_device *dev = skb->dev;
 798        struct sock *sk = skb->sk;
 799        struct sk_buff *list_skb;
 800        bool has_mac, has_trans;
 801        int headroom, tailroom;
 802        int i, len, seg_len;
 803
 804        if (full_pkt)
 805                len = skb->len;
 806        else
 807                len = min_t(int, skb->len, MAX_HEADER + 128);
 808
 809        headroom = skb_headroom(skb);
 810        tailroom = skb_tailroom(skb);
 811
 812        has_mac = skb_mac_header_was_set(skb);
 813        has_trans = skb_transport_header_was_set(skb);
 814
 815        printk("%sskb len=%u headroom=%u headlen=%u tailroom=%u\n"
 816               "mac=(%d,%d) net=(%d,%d) trans=%d\n"
 817               "shinfo(txflags=%u nr_frags=%u gso(size=%hu type=%u segs=%hu))\n"
 818               "csum(0x%x ip_summed=%u complete_sw=%u valid=%u level=%u)\n"
 819               "hash(0x%x sw=%u l4=%u) proto=0x%04x pkttype=%u iif=%d\n",
 820               level, skb->len, headroom, skb_headlen(skb), tailroom,
 821               has_mac ? skb->mac_header : -1,
 822               has_mac ? skb_mac_header_len(skb) : -1,
 823               skb->network_header,
 824               has_trans ? skb_network_header_len(skb) : -1,
 825               has_trans ? skb->transport_header : -1,
 826               sh->tx_flags, sh->nr_frags,
 827               sh->gso_size, sh->gso_type, sh->gso_segs,
 828               skb->csum, skb->ip_summed, skb->csum_complete_sw,
 829               skb->csum_valid, skb->csum_level,
 830               skb->hash, skb->sw_hash, skb->l4_hash,
 831               ntohs(skb->protocol), skb->pkt_type, skb->skb_iif);
 832
 833        if (dev)
 834                printk("%sdev name=%s feat=0x%pNF\n",
 835                       level, dev->name, &dev->features);
 836        if (sk)
 837                printk("%ssk family=%hu type=%u proto=%u\n",
 838                       level, sk->sk_family, sk->sk_type, sk->sk_protocol);
 839
 840        if (full_pkt && headroom)
 841                print_hex_dump(level, "skb headroom: ", DUMP_PREFIX_OFFSET,
 842                               16, 1, skb->head, headroom, false);
 843
 844        seg_len = min_t(int, skb_headlen(skb), len);
 845        if (seg_len)
 846                print_hex_dump(level, "skb linear:   ", DUMP_PREFIX_OFFSET,
 847                               16, 1, skb->data, seg_len, false);
 848        len -= seg_len;
 849
 850        if (full_pkt && tailroom)
 851                print_hex_dump(level, "skb tailroom: ", DUMP_PREFIX_OFFSET,
 852                               16, 1, skb_tail_pointer(skb), tailroom, false);
 853
 854        for (i = 0; len && i < skb_shinfo(skb)->nr_frags; i++) {
 855                skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 856                u32 p_off, p_len, copied;
 857                struct page *p;
 858                u8 *vaddr;
 859
 860                skb_frag_foreach_page(frag, skb_frag_off(frag),
 861                                      skb_frag_size(frag), p, p_off, p_len,
 862                                      copied) {
 863                        seg_len = min_t(int, p_len, len);
 864                        vaddr = kmap_atomic(p);
 865                        print_hex_dump(level, "skb frag:     ",
 866                                       DUMP_PREFIX_OFFSET,
 867                                       16, 1, vaddr + p_off, seg_len, false);
 868                        kunmap_atomic(vaddr);
 869                        len -= seg_len;
 870                        if (!len)
 871                                break;
 872                }
 873        }
 874
 875        if (full_pkt && skb_has_frag_list(skb)) {
 876                printk("skb fraglist:\n");
 877                skb_walk_frags(skb, list_skb)
 878                        skb_dump(level, list_skb, true);
 879        }
 880}
 881EXPORT_SYMBOL(skb_dump);
 882
 883/**
 884 *      skb_tx_error - report an sk_buff xmit error
 885 *      @skb: buffer that triggered an error
 886 *
 887 *      Report xmit error if a device callback is tracking this skb.
 888 *      skb must be freed afterwards.
 889 */
 890void skb_tx_error(struct sk_buff *skb)
 891{
 892        skb_zcopy_clear(skb, true);
 893}
 894EXPORT_SYMBOL(skb_tx_error);
 895
 896#ifdef CONFIG_TRACEPOINTS
 897/**
 898 *      consume_skb - free an skbuff
 899 *      @skb: buffer to free
 900 *
 901 *      Drop a ref to the buffer and free it if the usage count has hit zero
 902 *      Functions identically to kfree_skb, but kfree_skb assumes that the frame
 903 *      is being dropped after a failure and notes that
 904 */
 905void consume_skb(struct sk_buff *skb)
 906{
 907        if (!skb_unref(skb))
 908                return;
 909
 910        trace_consume_skb(skb);
 911        __kfree_skb(skb);
 912}
 913EXPORT_SYMBOL(consume_skb);
 914#endif
 915
 916/**
 917 *      __consume_stateless_skb - free an skbuff, assuming it is stateless
 918 *      @skb: buffer to free
 919 *
 920 *      Alike consume_skb(), but this variant assumes that this is the last
 921 *      skb reference and all the head states have been already dropped
 922 */
 923void __consume_stateless_skb(struct sk_buff *skb)
 924{
 925        trace_consume_skb(skb);
 926        skb_release_data(skb);
 927        kfree_skbmem(skb);
 928}
 929
 930static void napi_skb_cache_put(struct sk_buff *skb)
 931{
 932        struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
 933        u32 i;
 934
 935        kasan_poison_object_data(skbuff_head_cache, skb);
 936        nc->skb_cache[nc->skb_count++] = skb;
 937
 938        if (unlikely(nc->skb_count == NAPI_SKB_CACHE_SIZE)) {
 939                for (i = NAPI_SKB_CACHE_HALF; i < NAPI_SKB_CACHE_SIZE; i++)
 940                        kasan_unpoison_object_data(skbuff_head_cache,
 941                                                   nc->skb_cache[i]);
 942
 943                kmem_cache_free_bulk(skbuff_head_cache, NAPI_SKB_CACHE_HALF,
 944                                     nc->skb_cache + NAPI_SKB_CACHE_HALF);
 945                nc->skb_count = NAPI_SKB_CACHE_HALF;
 946        }
 947}
 948
 949void __kfree_skb_defer(struct sk_buff *skb)
 950{
 951        skb_release_all(skb);
 952        napi_skb_cache_put(skb);
 953}
 954
 955void napi_skb_free_stolen_head(struct sk_buff *skb)
 956{
 957        nf_reset_ct(skb);
 958        skb_dst_drop(skb);
 959        skb_ext_put(skb);
 960        napi_skb_cache_put(skb);
 961}
 962
 963void napi_consume_skb(struct sk_buff *skb, int budget)
 964{
 965        /* Zero budget indicate non-NAPI context called us, like netpoll */
 966        if (unlikely(!budget)) {
 967                dev_consume_skb_any(skb);
 968                return;
 969        }
 970
 971        lockdep_assert_in_softirq();
 972
 973        if (!skb_unref(skb))
 974                return;
 975
 976        /* if reaching here SKB is ready to free */
 977        trace_consume_skb(skb);
 978
 979        /* if SKB is a clone, don't handle this case */
 980        if (skb->fclone != SKB_FCLONE_UNAVAILABLE) {
 981                __kfree_skb(skb);
 982                return;
 983        }
 984
 985        skb_release_all(skb);
 986        napi_skb_cache_put(skb);
 987}
 988EXPORT_SYMBOL(napi_consume_skb);
 989
 990/* Make sure a field is enclosed inside headers_start/headers_end section */
 991#define CHECK_SKB_FIELD(field) \
 992        BUILD_BUG_ON(offsetof(struct sk_buff, field) <          \
 993                     offsetof(struct sk_buff, headers_start));  \
 994        BUILD_BUG_ON(offsetof(struct sk_buff, field) >          \
 995                     offsetof(struct sk_buff, headers_end));    \
 996
 997static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 998{
 999        new->tstamp             = old->tstamp;
1000        /* We do not copy old->sk */
1001        new->dev                = old->dev;
1002        memcpy(new->cb, old->cb, sizeof(old->cb));
1003        skb_dst_copy(new, old);
1004        __skb_ext_copy(new, old);
1005        __nf_copy(new, old, false);
1006
1007        /* Note : this field could be in headers_start/headers_end section
1008         * It is not yet because we do not want to have a 16 bit hole
1009         */
1010        new->queue_mapping = old->queue_mapping;
1011
1012        memcpy(&new->headers_start, &old->headers_start,
1013               offsetof(struct sk_buff, headers_end) -
1014               offsetof(struct sk_buff, headers_start));
1015        CHECK_SKB_FIELD(protocol);
1016        CHECK_SKB_FIELD(csum);
1017        CHECK_SKB_FIELD(hash);
1018        CHECK_SKB_FIELD(priority);
1019        CHECK_SKB_FIELD(skb_iif);
1020        CHECK_SKB_FIELD(vlan_proto);
1021        CHECK_SKB_FIELD(vlan_tci);
1022        CHECK_SKB_FIELD(transport_header);
1023        CHECK_SKB_FIELD(network_header);
1024        CHECK_SKB_FIELD(mac_header);
1025        CHECK_SKB_FIELD(inner_protocol);
1026        CHECK_SKB_FIELD(inner_transport_header);
1027        CHECK_SKB_FIELD(inner_network_header);
1028        CHECK_SKB_FIELD(inner_mac_header);
1029        CHECK_SKB_FIELD(mark);
1030#ifdef CONFIG_NETWORK_SECMARK
1031        CHECK_SKB_FIELD(secmark);
1032#endif
1033#ifdef CONFIG_NET_RX_BUSY_POLL
1034        CHECK_SKB_FIELD(napi_id);
1035#endif
1036#ifdef CONFIG_XPS
1037        CHECK_SKB_FIELD(sender_cpu);
1038#endif
1039#ifdef CONFIG_NET_SCHED
1040        CHECK_SKB_FIELD(tc_index);
1041#endif
1042
1043}
1044
1045/*
1046 * You should not add any new code to this function.  Add it to
1047 * __copy_skb_header above instead.
1048 */
1049static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
1050{
1051#define C(x) n->x = skb->x
1052
1053        n->next = n->prev = NULL;
1054        n->sk = NULL;
1055        __copy_skb_header(n, skb);
1056
1057        C(len);
1058        C(data_len);
1059        C(mac_len);
1060        n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
1061        n->cloned = 1;
1062        n->nohdr = 0;
1063        n->peeked = 0;
1064        C(pfmemalloc);
1065        C(pp_recycle);
1066        n->destructor = NULL;
1067        C(tail);
1068        C(end);
1069        C(head);
1070        C(head_frag);
1071        C(data);
1072        C(truesize);
1073        refcount_set(&n->users, 1);
1074
1075        atomic_inc(&(skb_shinfo(skb)->dataref));
1076        skb->cloned = 1;
1077
1078        return n;
1079#undef C
1080}
1081
1082/**
1083 * alloc_skb_for_msg() - allocate sk_buff to wrap frag list forming a msg
1084 * @first: first sk_buff of the msg
1085 */
1086struct sk_buff *alloc_skb_for_msg(struct sk_buff *first)
1087{
1088        struct sk_buff *n;
1089
1090        n = alloc_skb(0, GFP_ATOMIC);
1091        if (!n)
1092                return NULL;
1093
1094        n->len = first->len;
1095        n->data_len = first->len;
1096        n->truesize = first->truesize;
1097
1098        skb_shinfo(n)->frag_list = first;
1099
1100        __copy_skb_header(n, first);
1101        n->destructor = NULL;
1102
1103        return n;
1104}
1105EXPORT_SYMBOL_GPL(alloc_skb_for_msg);
1106
1107/**
1108 *      skb_morph       -       morph one skb into another
1109 *      @dst: the skb to receive the contents
1110 *      @src: the skb to supply the contents
1111 *
1112 *      This is identical to skb_clone except that the target skb is
1113 *      supplied by the user.
1114 *
1115 *      The target skb is returned upon exit.
1116 */
1117struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
1118{
1119        skb_release_all(dst);
1120        return __skb_clone(dst, src);
1121}
1122EXPORT_SYMBOL_GPL(skb_morph);
1123
1124int mm_account_pinned_pages(struct mmpin *mmp, size_t size)
1125{
1126        unsigned long max_pg, num_pg, new_pg, old_pg;
1127        struct user_struct *user;
1128
1129        if (capable(CAP_IPC_LOCK) || !size)
1130                return 0;
1131
1132        num_pg = (size >> PAGE_SHIFT) + 2;      /* worst case */
1133        max_pg = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
1134        user = mmp->user ? : current_user();
1135
1136        do {
1137                old_pg = atomic_long_read(&user->locked_vm);
1138                new_pg = old_pg + num_pg;
1139                if (new_pg > max_pg)
1140                        return -ENOBUFS;
1141        } while (atomic_long_cmpxchg(&user->locked_vm, old_pg, new_pg) !=
1142                 old_pg);
1143
1144        if (!mmp->user) {
1145                mmp->user = get_uid(user);
1146                mmp->num_pg = num_pg;
1147        } else {
1148                mmp->num_pg += num_pg;
1149        }
1150
1151        return 0;
1152}
1153EXPORT_SYMBOL_GPL(mm_account_pinned_pages);
1154
1155void mm_unaccount_pinned_pages(struct mmpin *mmp)
1156{
1157        if (mmp->user) {
1158                atomic_long_sub(mmp->num_pg, &mmp->user->locked_vm);
1159                free_uid(mmp->user);
1160        }
1161}
1162EXPORT_SYMBOL_GPL(mm_unaccount_pinned_pages);
1163
1164struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
1165{
1166        struct ubuf_info *uarg;
1167        struct sk_buff *skb;
1168
1169        WARN_ON_ONCE(!in_task());
1170
1171        skb = sock_omalloc(sk, 0, GFP_KERNEL);
1172        if (!skb)
1173                return NULL;
1174
1175        BUILD_BUG_ON(sizeof(*uarg) > sizeof(skb->cb));
1176        uarg = (void *)skb->cb;
1177        uarg->mmp.user = NULL;
1178
1179        if (mm_account_pinned_pages(&uarg->mmp, size)) {
1180                kfree_skb(skb);
1181                return NULL;
1182        }
1183
1184        uarg->callback = msg_zerocopy_callback;
1185        uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
1186        uarg->len = 1;
1187        uarg->bytelen = size;
1188        uarg->zerocopy = 1;
1189        uarg->flags = SKBFL_ZEROCOPY_FRAG;
1190        refcount_set(&uarg->refcnt, 1);
1191        sock_hold(sk);
1192
1193        return uarg;
1194}
1195EXPORT_SYMBOL_GPL(msg_zerocopy_alloc);
1196
1197static inline struct sk_buff *skb_from_uarg(struct ubuf_info *uarg)
1198{
1199        return container_of((void *)uarg, struct sk_buff, cb);
1200}
1201
1202struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
1203                                       struct ubuf_info *uarg)
1204{
1205        if (uarg) {
1206                const u32 byte_limit = 1 << 19;         /* limit to a few TSO */
1207                u32 bytelen, next;
1208
1209                /* realloc only when socket is locked (TCP, UDP cork),
1210                 * so uarg->len and sk_zckey access is serialized
1211                 */
1212                if (!sock_owned_by_user(sk)) {
1213                        WARN_ON_ONCE(1);
1214                        return NULL;
1215                }
1216
1217                bytelen = uarg->bytelen + size;
1218                if (uarg->len == USHRT_MAX - 1 || bytelen > byte_limit) {
1219                        /* TCP can create new skb to attach new uarg */
1220                        if (sk->sk_type == SOCK_STREAM)
1221                                goto new_alloc;
1222                        return NULL;
1223                }
1224
1225                next = (u32)atomic_read(&sk->sk_zckey);
1226                if ((u32)(uarg->id + uarg->len) == next) {
1227                        if (mm_account_pinned_pages(&uarg->mmp, size))
1228                                return NULL;
1229                        uarg->len++;
1230                        uarg->bytelen = bytelen;
1231                        atomic_set(&sk->sk_zckey, ++next);
1232
1233                        /* no extra ref when appending to datagram (MSG_MORE) */
1234                        if (sk->sk_type == SOCK_STREAM)
1235                                net_zcopy_get(uarg);
1236
1237                        return uarg;
1238                }
1239        }
1240
1241new_alloc:
1242        return msg_zerocopy_alloc(sk, size);
1243}
1244EXPORT_SYMBOL_GPL(msg_zerocopy_realloc);
1245
1246static bool skb_zerocopy_notify_extend(struct sk_buff *skb, u32 lo, u16 len)
1247{
1248        struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
1249        u32 old_lo, old_hi;
1250        u64 sum_len;
1251
1252        old_lo = serr->ee.ee_info;
1253        old_hi = serr->ee.ee_data;
1254        sum_len = old_hi - old_lo + 1ULL + len;
1255
1256        if (sum_len >= (1ULL << 32))
1257                return false;
1258
1259        if (lo != old_hi + 1)
1260                return false;
1261
1262        serr->ee.ee_data += len;
1263        return true;
1264}
1265
1266static void __msg_zerocopy_callback(struct ubuf_info *uarg)
1267{
1268        struct sk_buff *tail, *skb = skb_from_uarg(uarg);
1269        struct sock_exterr_skb *serr;
1270        struct sock *sk = skb->sk;
1271        struct sk_buff_head *q;
1272        unsigned long flags;
1273        bool is_zerocopy;
1274        u32 lo, hi;
1275        u16 len;
1276
1277        mm_unaccount_pinned_pages(&uarg->mmp);
1278
1279        /* if !len, there was only 1 call, and it was aborted
1280         * so do not queue a completion notification
1281         */
1282        if (!uarg->len || sock_flag(sk, SOCK_DEAD))
1283                goto release;
1284
1285        len = uarg->len;
1286        lo = uarg->id;
1287        hi = uarg->id + len - 1;
1288        is_zerocopy = uarg->zerocopy;
1289
1290        serr = SKB_EXT_ERR(skb);
1291        memset(serr, 0, sizeof(*serr));
1292        serr->ee.ee_errno = 0;
1293        serr->ee.ee_origin = SO_EE_ORIGIN_ZEROCOPY;
1294        serr->ee.ee_data = hi;
1295        serr->ee.ee_info = lo;
1296        if (!is_zerocopy)
1297                serr->ee.ee_code |= SO_EE_CODE_ZEROCOPY_COPIED;
1298
1299        q = &sk->sk_error_queue;
1300        spin_lock_irqsave(&q->lock, flags);
1301        tail = skb_peek_tail(q);
1302        if (!tail || SKB_EXT_ERR(tail)->ee.ee_origin != SO_EE_ORIGIN_ZEROCOPY ||
1303            !skb_zerocopy_notify_extend(tail, lo, len)) {
1304                __skb_queue_tail(q, skb);
1305                skb = NULL;
1306        }
1307        spin_unlock_irqrestore(&q->lock, flags);
1308
1309        sk_error_report(sk);
1310
1311release:
1312        consume_skb(skb);
1313        sock_put(sk);
1314}
1315
1316void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
1317                           bool success)
1318{
1319        uarg->zerocopy = uarg->zerocopy & success;
1320
1321        if (refcount_dec_and_test(&uarg->refcnt))
1322                __msg_zerocopy_callback(uarg);
1323}
1324EXPORT_SYMBOL_GPL(msg_zerocopy_callback);
1325
1326void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
1327{
1328        struct sock *sk = skb_from_uarg(uarg)->sk;
1329
1330        atomic_dec(&sk->sk_zckey);
1331        uarg->len--;
1332
1333        if (have_uref)
1334                msg_zerocopy_callback(NULL, uarg, true);
1335}
1336EXPORT_SYMBOL_GPL(msg_zerocopy_put_abort);
1337
1338int skb_zerocopy_iter_dgram(struct sk_buff *skb, struct msghdr *msg, int len)
1339{
1340        return __zerocopy_sg_from_iter(skb->sk, skb, &msg->msg_iter, len);
1341}
1342EXPORT_SYMBOL_GPL(skb_zerocopy_iter_dgram);
1343
1344int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
1345                             struct msghdr *msg, int len,
1346                             struct ubuf_info *uarg)
1347{
1348        struct ubuf_info *orig_uarg = skb_zcopy(skb);
1349        struct iov_iter orig_iter = msg->msg_iter;
1350        int err, orig_len = skb->len;
1351
1352        /* An skb can only point to one uarg. This edge case happens when
1353         * TCP appends to an skb, but zerocopy_realloc triggered a new alloc.
1354         */
1355        if (orig_uarg && uarg != orig_uarg)
1356                return -EEXIST;
1357
1358        err = __zerocopy_sg_from_iter(sk, skb, &msg->msg_iter, len);
1359        if (err == -EFAULT || (err == -EMSGSIZE && skb->len == orig_len)) {
1360                struct sock *save_sk = skb->sk;
1361
1362                /* Streams do not free skb on error. Reset to prev state. */
1363                msg->msg_iter = orig_iter;
1364                skb->sk = sk;
1365                ___pskb_trim(skb, orig_len);
1366                skb->sk = save_sk;
1367                return err;
1368        }
1369
1370        skb_zcopy_set(skb, uarg, NULL);
1371        return skb->len - orig_len;
1372}
1373EXPORT_SYMBOL_GPL(skb_zerocopy_iter_stream);
1374
1375static int skb_zerocopy_clone(struct sk_buff *nskb, struct sk_buff *orig,
1376                              gfp_t gfp_mask)
1377{
1378        if (skb_zcopy(orig)) {
1379                if (skb_zcopy(nskb)) {
1380                        /* !gfp_mask callers are verified to !skb_zcopy(nskb) */
1381                        if (!gfp_mask) {
1382                                WARN_ON_ONCE(1);
1383                                return -ENOMEM;
1384                        }
1385                        if (skb_uarg(nskb) == skb_uarg(orig))
1386                                return 0;
1387                        if (skb_copy_ubufs(nskb, GFP_ATOMIC))
1388                                return -EIO;
1389                }
1390                skb_zcopy_set(nskb, skb_uarg(orig), NULL);
1391        }
1392        return 0;
1393}
1394
1395/**
1396 *      skb_copy_ubufs  -       copy userspace skb frags buffers to kernel
1397 *      @skb: the skb to modify
1398 *      @gfp_mask: allocation priority
1399 *
1400 *      This must be called on skb with SKBFL_ZEROCOPY_ENABLE.
1401 *      It will copy all frags into kernel and drop the reference
1402 *      to userspace pages.
1403 *
1404 *      If this function is called from an interrupt gfp_mask() must be
1405 *      %GFP_ATOMIC.
1406 *
1407 *      Returns 0 on success or a negative error code on failure
1408 *      to allocate kernel memory to copy to.
1409 */
1410int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
1411{
1412        int num_frags = skb_shinfo(skb)->nr_frags;
1413        struct page *page, *head = NULL;
1414        int i, new_frags;
1415        u32 d_off;
1416
1417        if (skb_shared(skb) || skb_unclone(skb, gfp_mask))
1418                return -EINVAL;
1419
1420        if (!num_frags)
1421                goto release;
1422
1423        new_frags = (__skb_pagelen(skb) + PAGE_SIZE - 1) >> PAGE_SHIFT;
1424        for (i = 0; i < new_frags; i++) {
1425                page = alloc_page(gfp_mask);
1426                if (!page) {
1427                        while (head) {
1428                                struct page *next = (struct page *)page_private(head);
1429                                put_page(head);
1430                                head = next;
1431                        }
1432                        return -ENOMEM;
1433                }
1434                set_page_private(page, (unsigned long)head);
1435                head = page;
1436        }
1437
1438        page = head;
1439        d_off = 0;
1440        for (i = 0; i < num_frags; i++) {
1441                skb_frag_t *f = &skb_shinfo(skb)->frags[i];
1442                u32 p_off, p_len, copied;
1443                struct page *p;
1444                u8 *vaddr;
1445
1446                skb_frag_foreach_page(f, skb_frag_off(f), skb_frag_size(f),
1447                                      p, p_off, p_len, copied) {
1448                        u32 copy, done = 0;
1449                        vaddr = kmap_atomic(p);
1450
1451                        while (done < p_len) {
1452                                if (d_off == PAGE_SIZE) {
1453                                        d_off = 0;
1454                                        page = (struct page *)page_private(page);
1455                                }
1456                                copy = min_t(u32, PAGE_SIZE - d_off, p_len - done);
1457                                memcpy(page_address(page) + d_off,
1458                                       vaddr + p_off + done, copy);
1459                                done += copy;
1460                                d_off += copy;
1461                        }
1462                        kunmap_atomic(vaddr);
1463                }
1464        }
1465
1466        /* skb frags release userspace buffers */
1467        for (i = 0; i < num_frags; i++)
1468                skb_frag_unref(skb, i);
1469
1470        /* skb frags point to kernel buffers */
1471        for (i = 0; i < new_frags - 1; i++) {
1472                __skb_fill_page_desc(skb, i, head, 0, PAGE_SIZE);
1473                head = (struct page *)page_private(head);
1474        }
1475        __skb_fill_page_desc(skb, new_frags - 1, head, 0, d_off);
1476        skb_shinfo(skb)->nr_frags = new_frags;
1477
1478release:
1479        skb_zcopy_clear(skb, false);
1480        return 0;
1481}
1482EXPORT_SYMBOL_GPL(skb_copy_ubufs);
1483
1484/**
1485 *      skb_clone       -       duplicate an sk_buff
1486 *      @skb: buffer to clone
1487 *      @gfp_mask: allocation priority
1488 *
1489 *      Duplicate an &sk_buff. The new one is not owned by a socket. Both
1490 *      copies share the same packet data but not structure. The new
1491 *      buffer has a reference count of 1. If the allocation fails the
1492 *      function returns %NULL otherwise the new buffer is returned.
1493 *
1494 *      If this function is called from an interrupt gfp_mask() must be
1495 *      %GFP_ATOMIC.
1496 */
1497
1498struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
1499{
1500        struct sk_buff_fclones *fclones = container_of(skb,
1501                                                       struct sk_buff_fclones,
1502                                                       skb1);
1503        struct sk_buff *n;
1504
1505        if (skb_orphan_frags(skb, gfp_mask))
1506                return NULL;
1507
1508        if (skb->fclone == SKB_FCLONE_ORIG &&
1509            refcount_read(&fclones->fclone_ref) == 1) {
1510                n = &fclones->skb2;
1511                refcount_set(&fclones->fclone_ref, 2);
1512        } else {
1513                if (skb_pfmemalloc(skb))
1514                        gfp_mask |= __GFP_MEMALLOC;
1515
1516                n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
1517                if (!n)
1518                        return NULL;
1519
1520                n->fclone = SKB_FCLONE_UNAVAILABLE;
1521        }
1522
1523        return __skb_clone(n, skb);
1524}
1525EXPORT_SYMBOL(skb_clone);
1526
1527void skb_headers_offset_update(struct sk_buff *skb, int off)
1528{
1529        /* Only adjust this if it actually is csum_start rather than csum */
1530        if (skb->ip_summed == CHECKSUM_PARTIAL)
1531                skb->csum_start += off;
1532        /* {transport,network,mac}_header and tail are relative to skb->head */
1533        skb->transport_header += off;
1534        skb->network_header   += off;
1535        if (skb_mac_header_was_set(skb))
1536                skb->mac_header += off;
1537        skb->inner_transport_header += off;
1538        skb->inner_network_header += off;
1539        skb->inner_mac_header += off;
1540}
1541EXPORT_SYMBOL(skb_headers_offset_update);
1542
1543void skb_copy_header(struct sk_buff *new, const struct sk_buff *old)
1544{
1545        __copy_skb_header(new, old);
1546
1547        skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
1548        skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
1549        skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
1550}
1551EXPORT_SYMBOL(skb_copy_header);
1552
1553static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
1554{
1555        if (skb_pfmemalloc(skb))
1556                return SKB_ALLOC_RX;
1557        return 0;
1558}
1559
1560/**
1561 *      skb_copy        -       create private copy of an sk_buff
1562 *      @skb: buffer to copy
1563 *      @gfp_mask: allocation priority
1564 *
1565 *      Make a copy of both an &sk_buff and its data. This is used when the
1566 *      caller wishes to modify the data and needs a private copy of the
1567 *      data to alter. Returns %NULL on failure or the pointer to the buffer
1568 *      on success. The returned buffer has a reference count of 1.
1569 *
1570 *      As by-product this function converts non-linear &sk_buff to linear
1571 *      one, so that &sk_buff becomes completely private and caller is allowed
1572 *      to modify all the data of returned buffer. This means that this
1573 *      function is not recommended for use in circumstances when only
1574 *      header is going to be modified. Use pskb_copy() instead.
1575 */
1576
1577struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
1578{
1579        int headerlen = skb_headroom(skb);
1580        unsigned int size = skb_end_offset(skb) + skb->data_len;
1581        struct sk_buff *n = __alloc_skb(size, gfp_mask,
1582                                        skb_alloc_rx_flag(skb), NUMA_NO_NODE);
1583
1584        if (!n)
1585                return NULL;
1586
1587        /* Set the data pointer */
1588        skb_reserve(n, headerlen);
1589        /* Set the tail pointer and length */
1590        skb_put(n, skb->len);
1591
1592        BUG_ON(skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len));
1593
1594        skb_copy_header(n, skb);
1595        return n;
1596}
1597EXPORT_SYMBOL(skb_copy);
1598
1599/**
1600 *      __pskb_copy_fclone      -  create copy of an sk_buff with private head.
1601 *      @skb: buffer to copy
1602 *      @headroom: headroom of new skb
1603 *      @gfp_mask: allocation priority
1604 *      @fclone: if true allocate the copy of the skb from the fclone
1605 *      cache instead of the head cache; it is recommended to set this
1606 *      to true for the cases where the copy will likely be cloned
1607 *
1608 *      Make a copy of both an &sk_buff and part of its data, located
1609 *      in header. Fragmented data remain shared. This is used when
1610 *      the caller wishes to modify only header of &sk_buff and needs
1611 *      private copy of the header to alter. Returns %NULL on failure
1612 *      or the pointer to the buffer on success.
1613 *      The returned buffer has a reference count of 1.
1614 */
1615
1616struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
1617                                   gfp_t gfp_mask, bool fclone)
1618{
1619        unsigned int size = skb_headlen(skb) + headroom;
1620        int flags = skb_alloc_rx_flag(skb) | (fclone ? SKB_ALLOC_FCLONE : 0);
1621        struct sk_buff *n = __alloc_skb(size, gfp_mask, flags, NUMA_NO_NODE);
1622
1623        if (!n)
1624                goto out;
1625
1626        /* Set the data pointer */
1627        skb_reserve(n, headroom);
1628        /* Set the tail pointer and length */
1629        skb_put(n, skb_headlen(skb));
1630        /* Copy the bytes */
1631        skb_copy_from_linear_data(skb, n->data, n->len);
1632
1633        n->truesize += skb->data_len;
1634        n->data_len  = skb->data_len;
1635        n->len       = skb->len;
1636
1637        if (skb_shinfo(skb)->nr_frags) {
1638                int i;
1639
1640                if (skb_orphan_frags(skb, gfp_mask) ||
1641                    skb_zerocopy_clone(n, skb, gfp_mask)) {
1642                        kfree_skb(n);
1643                        n = NULL;
1644                        goto out;
1645                }
1646                for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1647                        skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
1648                        skb_frag_ref(skb, i);
1649                }
1650                skb_shinfo(n)->nr_frags = i;
1651        }
1652
1653        if (skb_has_frag_list(skb)) {
1654                skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
1655                skb_clone_fraglist(n);
1656        }
1657
1658        skb_copy_header(n, skb);
1659out:
1660        return n;
1661}
1662EXPORT_SYMBOL(__pskb_copy_fclone);
1663
1664/**
1665 *      pskb_expand_head - reallocate header of &sk_buff
1666 *      @skb: buffer to reallocate
1667 *      @nhead: room to add at head
1668 *      @ntail: room to add at tail
1669 *      @gfp_mask: allocation priority
1670 *
1671 *      Expands (or creates identical copy, if @nhead and @ntail are zero)
1672 *      header of @skb. &sk_buff itself is not changed. &sk_buff MUST have
1673 *      reference count of 1. Returns zero in the case of success or error,
1674 *      if expansion failed. In the last case, &sk_buff is not changed.
1675 *
1676 *      All the pointers pointing into skb header may change and must be
1677 *      reloaded after call to this function.
1678 */
1679
1680int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
1681                     gfp_t gfp_mask)
1682{
1683        int i, osize = skb_end_offset(skb);
1684        int size = osize + nhead + ntail;
1685        long off;
1686        u8 *data;
1687
1688        BUG_ON(nhead < 0);
1689
1690        BUG_ON(skb_shared(skb));
1691
1692        size = SKB_DATA_ALIGN(size);
1693
1694        if (skb_pfmemalloc(skb))
1695                gfp_mask |= __GFP_MEMALLOC;
1696        data = kmalloc_reserve(size + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
1697                               gfp_mask, NUMA_NO_NODE, NULL);
1698        if (!data)
1699                goto nodata;
1700        size = SKB_WITH_OVERHEAD(ksize(data));
1701
1702        /* Copy only real data... and, alas, header. This should be
1703         * optimized for the cases when header is void.
1704         */
1705        memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);
1706
1707        memcpy((struct skb_shared_info *)(data + size),
1708               skb_shinfo(skb),
1709               offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
1710
1711        /*
1712         * if shinfo is shared we must drop the old head gracefully, but if it
1713         * is not we can just drop the old head and let the existing refcount
1714         * be since all we did is relocate the values
1715         */
1716        if (skb_cloned(skb)) {
1717                if (skb_orphan_frags(skb, gfp_mask))
1718                        goto nofrags;
1719                if (skb_zcopy(skb))
1720                        refcount_inc(&skb_uarg(skb)->refcnt);
1721                for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
1722                        skb_frag_ref(skb, i);
1723
1724                if (skb_has_frag_list(skb))
1725                        skb_clone_fraglist(skb);
1726
1727                skb_release_data(skb);
1728        } else {
1729                skb_free_head(skb);
1730        }
1731        off = (data + nhead) - skb->head;
1732
1733        skb->head     = data;
1734        skb->head_frag = 0;
1735        skb->data    += off;
1736#ifdef NET_SKBUFF_DATA_USES_OFFSET
1737        skb->end      = size;
1738        off           = nhead;
1739#else
1740        skb->end      = skb->head + size;
1741#endif
1742        skb->tail             += off;
1743        skb_headers_offset_update(skb, nhead);
1744        skb->cloned   = 0;
1745        skb->hdr_len  = 0;
1746        skb->nohdr    = 0;
1747        atomic_set(&skb_shinfo(skb)->dataref, 1);
1748
1749        skb_metadata_clear(skb);
1750
1751        /* It is not generally safe to change skb->truesize.
1752         * For the moment, we really care of rx path, or
1753         * when skb is orphaned (not attached to a socket).
1754         */
1755        if (!skb->sk || skb->destructor == sock_edemux)
1756                skb->truesize += size - osize;
1757
1758        return 0;
1759
1760nofrags:
1761        kfree(data);
1762nodata:
1763        return -ENOMEM;
1764}
1765EXPORT_SYMBOL(pskb_expand_head);
1766
1767/* Make private copy of skb with writable head and some headroom */
1768
1769struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
1770{
1771        struct sk_buff *skb2;
1772        int delta = headroom - skb_headroom(skb);
1773
1774        if (delta <= 0)
1775                skb2 = pskb_copy(skb, GFP_ATOMIC);
1776        else {
1777                skb2 = skb_clone(skb, GFP_ATOMIC);
1778                if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
1779                                             GFP_ATOMIC)) {
1780                        kfree_skb(skb2);
1781                        skb2 = NULL;
1782                }
1783        }
1784        return skb2;
1785}
1786EXPORT_SYMBOL(skb_realloc_headroom);
1787
1788/**
1789 *      skb_copy_expand -       copy and expand sk_buff
1790 *      @skb: buffer to copy
1791 *      @newheadroom: new free bytes at head
1792 *      @newtailroom: new free bytes at tail
1793 *      @gfp_mask: allocation priority
1794 *
1795 *      Make a copy of both an &sk_buff and its data and while doing so
1796 *      allocate additional space.
1797 *
1798 *      This is used when the caller wishes to modify the data and needs a
1799 *      private copy of the data to alter as well as more space for new fields.
1800 *      Returns %NULL on failure or the pointer to the buffer
1801 *      on success. The returned buffer has a reference count of 1.
1802 *
1803 *      You must pass %GFP_ATOMIC as the allocation priority if this function
1804 *      is called from an interrupt.
1805 */
1806struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
1807                                int newheadroom, int newtailroom,
1808                                gfp_t gfp_mask)
1809{
1810        /*
1811         *      Allocate the copy buffer
1812         */
1813        struct sk_buff *n = __alloc_skb(newheadroom + skb->len + newtailroom,
1814                                        gfp_mask, skb_alloc_rx_flag(skb),
1815                                        NUMA_NO_NODE);
1816        int oldheadroom = skb_headroom(skb);
1817        int head_copy_len, head_copy_off;
1818
1819        if (!n)
1820                return NULL;
1821
1822        skb_reserve(n, newheadroom);
1823
1824        /* Set the tail pointer and length */
1825        skb_put(n, skb->len);
1826
1827        head_copy_len = oldheadroom;
1828        head_copy_off = 0;
1829        if (newheadroom <= head_copy_len)
1830                head_copy_len = newheadroom;
1831        else
1832                head_copy_off = newheadroom - head_copy_len;
1833
1834        /* Copy the linear header and data. */
1835        BUG_ON(skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
1836                             skb->len + head_copy_len));
1837
1838        skb_copy_header(n, skb);
1839
1840        skb_headers_offset_update(n, newheadroom - oldheadroom);
1841
1842        return n;
1843}
1844EXPORT_SYMBOL(skb_copy_expand);
1845
1846/**
1847 *      __skb_pad               -       zero pad the tail of an skb
1848 *      @skb: buffer to pad
1849 *      @pad: space to pad
1850 *      @free_on_error: free buffer on error
1851 *
1852 *      Ensure that a buffer is followed by a padding area that is zero
1853 *      filled. Used by network drivers which may DMA or transfer data
1854 *      beyond the buffer end onto the wire.
1855 *
1856 *      May return error in out of memory cases. The skb is freed on error
1857 *      if @free_on_error is true.
1858 */
1859
1860int __skb_pad(struct sk_buff *skb, int pad, bool free_on_error)
1861{
1862        int err;
1863        int ntail;
1864
1865        /* If the skbuff is non linear tailroom is always zero.. */
1866        if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
1867                memset(skb->data+skb->len, 0, pad);
1868                return 0;
1869        }
1870
1871        ntail = skb->data_len + pad - (skb->end - skb->tail);
1872        if (likely(skb_cloned(skb) || ntail > 0)) {
1873                err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
1874                if (unlikely(err))
1875                        goto free_skb;
1876        }
1877
1878        /* FIXME: The use of this function with non-linear skb's really needs
1879         * to be audited.
1880         */
1881        err = skb_linearize(skb);
1882        if (unlikely(err))
1883                goto free_skb;
1884
1885        memset(skb->data + skb->len, 0, pad);
1886        return 0;
1887
1888free_skb:
1889        if (free_on_error)
1890                kfree_skb(skb);
1891        return err;
1892}
1893EXPORT_SYMBOL(__skb_pad);
1894
1895/**
1896 *      pskb_put - add data to the tail of a potentially fragmented buffer
1897 *      @skb: start of the buffer to use
1898 *      @tail: tail fragment of the buffer to use
1899 *      @len: amount of data to add
1900 *
1901 *      This function extends the used data area of the potentially
1902 *      fragmented buffer. @tail must be the last fragment of @skb -- or
1903 *      @skb itself. If this would exceed the total buffer size the kernel
1904 *      will panic. A pointer to the first byte of the extra data is
1905 *      returned.
1906 */
1907
1908void *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len)
1909{
1910        if (tail != skb) {
1911                skb->data_len += len;
1912                skb->len += len;
1913        }
1914        return skb_put(tail, len);
1915}
1916EXPORT_SYMBOL_GPL(pskb_put);
1917
1918/**
1919 *      skb_put - add data to a buffer
1920 *      @skb: buffer to use
1921 *      @len: amount of data to add
1922 *
1923 *      This function extends the used data area of the buffer. If this would
1924 *      exceed the total buffer size the kernel will panic. A pointer to the
1925 *      first byte of the extra data is returned.
1926 */
1927void *skb_put(struct sk_buff *skb, unsigned int len)
1928{
1929        void *tmp = skb_tail_pointer(skb);
1930        SKB_LINEAR_ASSERT(skb);
1931        skb->tail += len;
1932        skb->len  += len;
1933        if (unlikely(skb->tail > skb->end))
1934                skb_over_panic(skb, len, __builtin_return_address(0));
1935        return tmp;
1936}
1937EXPORT_SYMBOL(skb_put);
1938
1939/**
1940 *      skb_push - add data to the start of a buffer
1941 *      @skb: buffer to use
1942 *      @len: amount of data to add
1943 *
1944 *      This function extends the used data area of the buffer at the buffer
1945 *      start. If this would exceed the total buffer headroom the kernel will
1946 *      panic. A pointer to the first byte of the extra data is returned.
1947 */
1948void *skb_push(struct sk_buff *skb, unsigned int len)
1949{
1950        skb->data -= len;
1951        skb->len  += len;
1952        if (unlikely(skb->data < skb->head))
1953                skb_under_panic(skb, len, __builtin_return_address(0));
1954        return skb->data;
1955}
1956EXPORT_SYMBOL(skb_push);
1957
1958/**
1959 *      skb_pull - remove data from the start of a buffer
1960 *      @skb: buffer to use
1961 *      @len: amount of data to remove
1962 *
1963 *      This function removes data from the start of a buffer, returning
1964 *      the memory to the headroom. A pointer to the next data in the buffer
1965 *      is returned. Once the data has been pulled future pushes will overwrite
1966 *      the old data.
1967 */
1968void *skb_pull(struct sk_buff *skb, unsigned int len)
1969{
1970        return skb_pull_inline(skb, len);
1971}
1972EXPORT_SYMBOL(skb_pull);
1973
1974/**
1975 *      skb_trim - remove end from a buffer
1976 *      @skb: buffer to alter
1977 *      @len: new length
1978 *
1979 *      Cut the length of a buffer down by removing data from the tail. If
1980 *      the buffer is already under the length specified it is not modified.
1981 *      The skb must be linear.
1982 */
1983void skb_trim(struct sk_buff *skb, unsigned int len)
1984{
1985        if (skb->len > len)
1986                __skb_trim(skb, len);
1987}
1988EXPORT_SYMBOL(skb_trim);
1989
1990/* Trims skb to length len. It can change skb pointers.
1991 */
1992
1993int ___pskb_trim(struct sk_buff *skb, unsigned int len)
1994{
1995        struct sk_buff **fragp;
1996        struct sk_buff *frag;
1997        int offset = skb_headlen(skb);
1998        int nfrags = skb_shinfo(skb)->nr_frags;
1999        int i;
2000        int err;
2001
2002        if (skb_cloned(skb) &&
2003            unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
2004                return err;
2005
2006        i = 0;
2007        if (offset >= len)
2008                goto drop_pages;
2009
2010        for (; i < nfrags; i++) {
2011                int end = offset + skb_frag_size(&skb_shinfo(skb)->frags[i]);
2012
2013                if (end < len) {
2014                        offset = end;
2015                        continue;
2016                }
2017
2018                skb_frag_size_set(&skb_shinfo(skb)->frags[i++], len - offset);
2019
2020drop_pages:
2021                skb_shinfo(skb)->nr_frags = i;
2022
2023                for (; i < nfrags; i++)
2024                        skb_frag_unref(skb, i);
2025
2026                if (skb_has_frag_list(skb))
2027                        skb_drop_fraglist(skb);
2028                goto done;
2029        }
2030
2031        for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
2032             fragp = &frag->next) {
2033                int end = offset + frag->len;
2034
2035                if (skb_shared(frag)) {
2036                        struct sk_buff *nfrag;
2037
2038                        nfrag = skb_clone(frag, GFP_ATOMIC);
2039                        if (unlikely(!nfrag))
2040                                return -ENOMEM;
2041
2042                        nfrag->next = frag->next;
2043                        consume_skb(frag);
2044                        frag = nfrag;
2045                        *fragp = frag;
2046                }
2047
2048                if (end < len) {
2049                        offset = end;
2050                        continue;
2051                }
2052
2053                if (end > len &&
2054                    unlikely((err = pskb_trim(frag, len - offset))))
2055                        return err;
2056
2057                if (frag->next)
2058                        skb_drop_list(&frag->next);
2059                break;
2060        }
2061
2062done:
2063        if (len > skb_headlen(skb)) {
2064                skb->data_len -= skb->len - len;
2065                skb->len       = len;
2066        } else {
2067                skb->len       = len;
2068                skb->data_len  = 0;
2069                skb_set_tail_pointer(skb, len);
2070        }
2071
2072        if (!skb->sk || skb->destructor == sock_edemux)
2073                skb_condense(skb);
2074        return 0;
2075}
2076EXPORT_SYMBOL(___pskb_trim);
2077
2078/* Note : use pskb_trim_rcsum() instead of calling this directly
2079 */
2080int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len)
2081{
2082        if (skb->ip_summed == CHECKSUM_COMPLETE) {
2083                int delta = skb->len - len;
2084
2085                skb->csum = csum_block_sub(skb->csum,
2086                                           skb_checksum(skb, len, delta, 0),
2087                                           len);
2088        } else if (skb->ip_summed == CHECKSUM_PARTIAL) {
2089                int hdlen = (len > skb_headlen(skb)) ? skb_headlen(skb) : len;
2090                int offset = skb_checksum_start_offset(skb) + skb->csum_offset;
2091
2092                if (offset + sizeof(__sum16) > hdlen)
2093                        return -EINVAL;
2094        }
2095        return __pskb_trim(skb, len);
2096}
2097EXPORT_SYMBOL(pskb_trim_rcsum_slow);
2098
2099/**
2100 *      __pskb_pull_tail - advance tail of skb header
2101 *      @skb: buffer to reallocate
2102 *      @delta: number of bytes to advance tail
2103 *
2104 *      The function makes a sense only on a fragmented &sk_buff,
2105 *      it expands header moving its tail forward and copying necessary
2106 *      data from fragmented part.
2107 *
2108 *      &sk_buff MUST have reference count of 1.
2109 *
2110 *      Returns %NULL (and &sk_buff does not change) if pull failed
2111 *      or value of new tail of skb in the case of success.
2112 *
2113 *      All the pointers pointing into skb header may change and must be
2114 *      reloaded after call to this function.
2115 */
2116
2117/* Moves tail of skb head forward, copying data from fragmented part,
2118 * when it is necessary.
2119 * 1. It may fail due to malloc failure.
2120 * 2. It may change skb pointers.
2121 *
2122 * It is pretty complicated. Luckily, it is called only in exceptional cases.
2123 */
2124void *__pskb_pull_tail(struct sk_buff *skb, int delta)
2125{
2126        /* If skb has not enough free space at tail, get new one
2127         * plus 128 bytes for future expansions. If we have enough
2128         * room at tail, reallocate without expansion only if skb is cloned.
2129         */
2130        int i, k, eat = (skb->tail + delta) - skb->end;
2131
2132        if (eat > 0 || skb_cloned(skb)) {
2133                if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
2134                                     GFP_ATOMIC))
2135                        return NULL;
2136        }
2137
2138        BUG_ON(skb_copy_bits(skb, skb_headlen(skb),
2139                             skb_tail_pointer(skb), delta));
2140
2141        /* Optimization: no fragments, no reasons to preestimate
2142         * size of pulled pages. Superb.
2143         */
2144        if (!skb_has_frag_list(skb))
2145                goto pull_pages;
2146
2147        /* Estimate size of pulled pages. */
2148        eat = delta;
2149        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2150                int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2151
2152                if (size >= eat)
2153                        goto pull_pages;
2154                eat -= size;
2155        }
2156
2157        /* If we need update frag list, we are in troubles.
2158         * Certainly, it is possible to add an offset to skb data,
2159         * but taking into account that pulling is expected to
2160         * be very rare operation, it is worth to fight against
2161         * further bloating skb head and crucify ourselves here instead.
2162         * Pure masohism, indeed. 8)8)
2163         */
2164        if (eat) {
2165                struct sk_buff *list = skb_shinfo(skb)->frag_list;
2166                struct sk_buff *clone = NULL;
2167                struct sk_buff *insp = NULL;
2168
2169                do {
2170                        if (list->len <= eat) {
2171                                /* Eaten as whole. */
2172                                eat -= list->len;
2173                                list = list->next;
2174                                insp = list;
2175                        } else {
2176                                /* Eaten partially. */
2177
2178                                if (skb_shared(list)) {
2179                                        /* Sucks! We need to fork list. :-( */
2180                                        clone = skb_clone(list, GFP_ATOMIC);
2181                                        if (!clone)
2182                                                return NULL;
2183                                        insp = list->next;
2184                                        list = clone;
2185                                } else {
2186                                        /* This may be pulled without
2187                                         * problems. */
2188                                        insp = list;
2189                                }
2190                                if (!pskb_pull(list, eat)) {
2191                                        kfree_skb(clone);
2192                                        return NULL;
2193                                }
2194                                break;
2195                        }
2196                } while (eat);
2197
2198                /* Free pulled out fragments. */
2199                while ((list = skb_shinfo(skb)->frag_list) != insp) {
2200                        skb_shinfo(skb)->frag_list = list->next;
2201                        kfree_skb(list);
2202                }
2203                /* And insert new clone at head. */
2204                if (clone) {
2205                        clone->next = list;
2206                        skb_shinfo(skb)->frag_list = clone;
2207                }
2208        }
2209        /* Success! Now we may commit changes to skb data. */
2210
2211pull_pages:
2212        eat = delta;
2213        k = 0;
2214        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2215                int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2216
2217                if (size <= eat) {
2218                        skb_frag_unref(skb, i);
2219                        eat -= size;
2220                } else {
2221                        skb_frag_t *frag = &skb_shinfo(skb)->frags[k];
2222
2223                        *frag = skb_shinfo(skb)->frags[i];
2224                        if (eat) {
2225                                skb_frag_off_add(frag, eat);
2226                                skb_frag_size_sub(frag, eat);
2227                                if (!i)
2228                                        goto end;
2229                                eat = 0;
2230                        }
2231                        k++;
2232                }
2233        }
2234        skb_shinfo(skb)->nr_frags = k;
2235
2236end:
2237        skb->tail     += delta;
2238        skb->data_len -= delta;
2239
2240        if (!skb->data_len)
2241                skb_zcopy_clear(skb, false);
2242
2243        return skb_tail_pointer(skb);
2244}
2245EXPORT_SYMBOL(__pskb_pull_tail);
2246
2247/**
2248 *      skb_copy_bits - copy bits from skb to kernel buffer
2249 *      @skb: source skb
2250 *      @offset: offset in source
2251 *      @to: destination buffer
2252 *      @len: number of bytes to copy
2253 *
2254 *      Copy the specified number of bytes from the source skb to the
2255 *      destination buffer.
2256 *
2257 *      CAUTION ! :
2258 *              If its prototype is ever changed,
2259 *              check arch/{*}/net/{*}.S files,
2260 *              since it is called from BPF assembly code.
2261 */
2262int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
2263{
2264        int start = skb_headlen(skb);
2265        struct sk_buff *frag_iter;
2266        int i, copy;
2267
2268        if (offset > (int)skb->len - len)
2269                goto fault;
2270
2271        /* Copy header. */
2272        if ((copy = start - offset) > 0) {
2273                if (copy > len)
2274                        copy = len;
2275                skb_copy_from_linear_data_offset(skb, offset, to, copy);
2276                if ((len -= copy) == 0)
2277                        return 0;
2278                offset += copy;
2279                to     += copy;
2280        }
2281
2282        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2283                int end;
2284                skb_frag_t *f = &skb_shinfo(skb)->frags[i];
2285
2286                WARN_ON(start > offset + len);
2287
2288                end = start + skb_frag_size(f);
2289                if ((copy = end - offset) > 0) {
2290                        u32 p_off, p_len, copied;
2291                        struct page *p;
2292                        u8 *vaddr;
2293
2294                        if (copy > len)
2295                                copy = len;
2296
2297                        skb_frag_foreach_page(f,
2298                                              skb_frag_off(f) + offset - start,
2299                                              copy, p, p_off, p_len, copied) {
2300                                vaddr = kmap_atomic(p);
2301                                memcpy(to + copied, vaddr + p_off, p_len);
2302                                kunmap_atomic(vaddr);
2303                        }
2304
2305                        if ((len -= copy) == 0)
2306                                return 0;
2307                        offset += copy;
2308                        to     += copy;
2309                }
2310                start = end;
2311        }
2312
2313        skb_walk_frags(skb, frag_iter) {
2314                int end;
2315
2316                WARN_ON(start > offset + len);
2317
2318                end = start + frag_iter->len;
2319                if ((copy = end - offset) > 0) {
2320                        if (copy > len)
2321                                copy = len;
2322                        if (skb_copy_bits(frag_iter, offset - start, to, copy))
2323                                goto fault;
2324                        if ((len -= copy) == 0)
2325                                return 0;
2326                        offset += copy;
2327                        to     += copy;
2328                }
2329                start = end;
2330        }
2331
2332        if (!len)
2333                return 0;
2334
2335fault:
2336        return -EFAULT;
2337}
2338EXPORT_SYMBOL(skb_copy_bits);
2339
2340/*
2341 * Callback from splice_to_pipe(), if we need to release some pages
2342 * at the end of the spd in case we error'ed out in filling the pipe.
2343 */
2344static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
2345{
2346        put_page(spd->pages[i]);
2347}
2348
2349static struct page *linear_to_page(struct page *page, unsigned int *len,
2350                                   unsigned int *offset,
2351                                   struct sock *sk)
2352{
2353        struct page_frag *pfrag = sk_page_frag(sk);
2354
2355        if (!sk_page_frag_refill(sk, pfrag))
2356                return NULL;
2357
2358        *len = min_t(unsigned int, *len, pfrag->size - pfrag->offset);
2359
2360        memcpy(page_address(pfrag->page) + pfrag->offset,
2361               page_address(page) + *offset, *len);
2362        *offset = pfrag->offset;
2363        pfrag->offset += *len;
2364
2365        return pfrag->page;
2366}
2367
2368static bool spd_can_coalesce(const struct splice_pipe_desc *spd,
2369                             struct page *page,
2370                             unsigned int offset)
2371{
2372        return  spd->nr_pages &&
2373                spd->pages[spd->nr_pages - 1] == page &&
2374                (spd->partial[spd->nr_pages - 1].offset +
2375                 spd->partial[spd->nr_pages - 1].len == offset);
2376}
2377
2378/*
2379 * Fill page/offset/length into spd, if it can hold more pages.
2380 */
2381static bool spd_fill_page(struct splice_pipe_desc *spd,
2382                          struct pipe_inode_info *pipe, struct page *page,
2383                          unsigned int *len, unsigned int offset,
2384                          bool linear,
2385                          struct sock *sk)
2386{
2387        if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
2388                return true;
2389
2390        if (linear) {
2391                page = linear_to_page(page, len, &offset, sk);
2392                if (!page)
2393                        return true;
2394        }
2395        if (spd_can_coalesce(spd, page, offset)) {
2396                spd->partial[spd->nr_pages - 1].len += *len;
2397                return false;
2398        }
2399        get_page(page);
2400        spd->pages[spd->nr_pages] = page;
2401        spd->partial[spd->nr_pages].len = *len;
2402        spd->partial[spd->nr_pages].offset = offset;
2403        spd->nr_pages++;
2404
2405        return false;
2406}
2407
2408static bool __splice_segment(struct page *page, unsigned int poff,
2409                             unsigned int plen, unsigned int *off,
2410                             unsigned int *len,
2411                             struct splice_pipe_desc *spd, bool linear,
2412                             struct sock *sk,
2413                             struct pipe_inode_info *pipe)
2414{
2415        if (!*len)
2416                return true;
2417
2418        /* skip this segment if already processed */
2419        if (*off >= plen) {
2420                *off -= plen;
2421                return false;
2422        }
2423
2424        /* ignore any bits we already processed */
2425        poff += *off;
2426        plen -= *off;
2427        *off = 0;
2428
2429        do {
2430                unsigned int flen = min(*len, plen);
2431
2432                if (spd_fill_page(spd, pipe, page, &flen, poff,
2433                                  linear, sk))
2434                        return true;
2435                poff += flen;
2436                plen -= flen;
2437                *len -= flen;
2438        } while (*len && plen);
2439
2440        return false;
2441}
2442
2443/*
2444 * Map linear and fragment data from the skb to spd. It reports true if the
2445 * pipe is full or if we already spliced the requested length.
2446 */
2447static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
2448                              unsigned int *offset, unsigned int *len,
2449                              struct splice_pipe_desc *spd, struct sock *sk)
2450{
2451        int seg;
2452        struct sk_buff *iter;
2453
2454        /* map the linear part :
2455         * If skb->head_frag is set, this 'linear' part is backed by a
2456         * fragment, and if the head is not shared with any clones then
2457         * we can avoid a copy since we own the head portion of this page.
2458         */
2459        if (__splice_segment(virt_to_page(skb->data),
2460                             (unsigned long) skb->data & (PAGE_SIZE - 1),
2461                             skb_headlen(skb),
2462                             offset, len, spd,
2463                             skb_head_is_locked(skb),
2464                             sk, pipe))
2465                return true;
2466
2467        /*
2468         * then map the fragments
2469         */
2470        for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
2471                const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
2472
2473                if (__splice_segment(skb_frag_page(f),
2474                                     skb_frag_off(f), skb_frag_size(f),
2475                                     offset, len, spd, false, sk, pipe))
2476                        return true;
2477        }
2478
2479        skb_walk_frags(skb, iter) {
2480                if (*offset >= iter->len) {
2481                        *offset -= iter->len;
2482                        continue;
2483                }
2484                /* __skb_splice_bits() only fails if the output has no room
2485                 * left, so no point in going over the frag_list for the error
2486                 * case.
2487                 */
2488                if (__skb_splice_bits(iter, pipe, offset, len, spd, sk))
2489                        return true;
2490        }
2491
2492        return false;
2493}
2494
2495/*
2496 * Map data from the skb to a pipe. Should handle both the linear part,
2497 * the fragments, and the frag list.
2498 */
2499int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
2500                    struct pipe_inode_info *pipe, unsigned int tlen,
2501                    unsigned int flags)
2502{
2503        struct partial_page partial[MAX_SKB_FRAGS];
2504        struct page *pages[MAX_SKB_FRAGS];
2505        struct splice_pipe_desc spd = {
2506                .pages = pages,
2507                .partial = partial,
2508                .nr_pages_max = MAX_SKB_FRAGS,
2509                .ops = &nosteal_pipe_buf_ops,
2510                .spd_release = sock_spd_release,
2511        };
2512        int ret = 0;
2513
2514        __skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk);
2515
2516        if (spd.nr_pages)
2517                ret = splice_to_pipe(pipe, &spd);
2518
2519        return ret;
2520}
2521EXPORT_SYMBOL_GPL(skb_splice_bits);
2522
2523static int sendmsg_unlocked(struct sock *sk, struct msghdr *msg,
2524                            struct kvec *vec, size_t num, size_t size)
2525{
2526        struct socket *sock = sk->sk_socket;
2527
2528        if (!sock)
2529                return -EINVAL;
2530        return kernel_sendmsg(sock, msg, vec, num, size);
2531}
2532
2533static int sendpage_unlocked(struct sock *sk, struct page *page, int offset,
2534                             size_t size, int flags)
2535{
2536        struct socket *sock = sk->sk_socket;
2537
2538        if (!sock)
2539                return -EINVAL;
2540        return kernel_sendpage(sock, page, offset, size, flags);
2541}
2542
2543typedef int (*sendmsg_func)(struct sock *sk, struct msghdr *msg,
2544                            struct kvec *vec, size_t num, size_t size);
2545typedef int (*sendpage_func)(struct sock *sk, struct page *page, int offset,
2546                             size_t size, int flags);
2547static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset,
2548                           int len, sendmsg_func sendmsg, sendpage_func sendpage)
2549{
2550        unsigned int orig_len = len;
2551        struct sk_buff *head = skb;
2552        unsigned short fragidx;
2553        int slen, ret;
2554
2555do_frag_list:
2556
2557        /* Deal with head data */
2558        while (offset < skb_headlen(skb) && len) {
2559                struct kvec kv;
2560                struct msghdr msg;
2561
2562                slen = min_t(int, len, skb_headlen(skb) - offset);
2563                kv.iov_base = skb->data + offset;
2564                kv.iov_len = slen;
2565                memset(&msg, 0, sizeof(msg));
2566                msg.msg_flags = MSG_DONTWAIT;
2567
2568                ret = INDIRECT_CALL_2(sendmsg, kernel_sendmsg_locked,
2569                                      sendmsg_unlocked, sk, &msg, &kv, 1, slen);
2570                if (ret <= 0)
2571                        goto error;
2572
2573                offset += ret;
2574                len -= ret;
2575        }
2576
2577        /* All the data was skb head? */
2578        if (!len)
2579                goto out;
2580
2581        /* Make offset relative to start of frags */
2582        offset -= skb_headlen(skb);
2583
2584        /* Find where we are in frag list */
2585        for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
2586                skb_frag_t *frag  = &skb_shinfo(skb)->frags[fragidx];
2587
2588                if (offset < skb_frag_size(frag))
2589                        break;
2590
2591                offset -= skb_frag_size(frag);
2592        }
2593
2594        for (; len && fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
2595                skb_frag_t *frag  = &skb_shinfo(skb)->frags[fragidx];
2596
2597                slen = min_t(size_t, len, skb_frag_size(frag) - offset);
2598
2599                while (slen) {
2600                        ret = INDIRECT_CALL_2(sendpage, kernel_sendpage_locked,
2601                                              sendpage_unlocked, sk,
2602                                              skb_frag_page(frag),
2603                                              skb_frag_off(frag) + offset,
2604                                              slen, MSG_DONTWAIT);
2605                        if (ret <= 0)
2606                                goto error;
2607
2608                        len -= ret;
2609                        offset += ret;
2610                        slen -= ret;
2611                }
2612
2613                offset = 0;
2614        }
2615
2616        if (len) {
2617                /* Process any frag lists */
2618
2619                if (skb == head) {
2620                        if (skb_has_frag_list(skb)) {
2621                                skb = skb_shinfo(skb)->frag_list;
2622                                goto do_frag_list;
2623                        }
2624                } else if (skb->next) {
2625                        skb = skb->next;
2626                        goto do_frag_list;
2627                }
2628        }
2629
2630out:
2631        return orig_len - len;
2632
2633error:
2634        return orig_len == len ? ret : orig_len - len;
2635}
2636
2637/* Send skb data on a socket. Socket must be locked. */
2638int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
2639                         int len)
2640{
2641        return __skb_send_sock(sk, skb, offset, len, kernel_sendmsg_locked,
2642                               kernel_sendpage_locked);
2643}
2644EXPORT_SYMBOL_GPL(skb_send_sock_locked);
2645
2646/* Send skb data on a socket. Socket must be unlocked. */
2647int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len)
2648{
2649        return __skb_send_sock(sk, skb, offset, len, sendmsg_unlocked,
2650                               sendpage_unlocked);
2651}
2652
2653/**
2654 *      skb_store_bits - store bits from kernel buffer to skb
2655 *      @skb: destination buffer
2656 *      @offset: offset in destination
2657 *      @from: source buffer
2658 *      @len: number of bytes to copy
2659 *
2660 *      Copy the specified number of bytes from the source buffer to the
2661 *      destination skb.  This function handles all the messy bits of
2662 *      traversing fragment lists and such.
2663 */
2664
2665int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
2666{
2667        int start = skb_headlen(skb);
2668        struct sk_buff *frag_iter;
2669        int i, copy;
2670
2671        if (offset > (int)skb->len - len)
2672                goto fault;
2673
2674        if ((copy = start - offset) > 0) {
2675                if (copy > len)
2676                        copy = len;
2677                skb_copy_to_linear_data_offset(skb, offset, from, copy);
2678                if ((len -= copy) == 0)
2679                        return 0;
2680                offset += copy;
2681                from += copy;
2682        }
2683
2684        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2685                skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2686                int end;
2687
2688                WARN_ON(start > offset + len);
2689
2690                end = start + skb_frag_size(frag);
2691                if ((copy = end - offset) > 0) {
2692                        u32 p_off, p_len, copied;
2693                        struct page *p;
2694                        u8 *vaddr;
2695
2696                        if (copy > len)
2697                                copy = len;
2698
2699                        skb_frag_foreach_page(frag,
2700                                              skb_frag_off(frag) + offset - start,
2701                                              copy, p, p_off, p_len, copied) {
2702                                vaddr = kmap_atomic(p);
2703                                memcpy(vaddr + p_off, from + copied, p_len);
2704                                kunmap_atomic(vaddr);
2705                        }
2706
2707                        if ((len -= copy) == 0)
2708                                return 0;
2709                        offset += copy;
2710                        from += copy;
2711                }
2712                start = end;
2713        }
2714
2715        skb_walk_frags(skb, frag_iter) {
2716                int end;
2717
2718                WARN_ON(start > offset + len);
2719
2720                end = start + frag_iter->len;
2721                if ((copy = end - offset) > 0) {
2722                        if (copy > len)
2723                                copy = len;
2724                        if (skb_store_bits(frag_iter, offset - start,
2725                                           from, copy))
2726                                goto fault;
2727                        if ((len -= copy) == 0)
2728                                return 0;
2729                        offset += copy;
2730                        from += copy;
2731                }
2732                start = end;
2733        }
2734        if (!len)
2735                return 0;
2736
2737fault:
2738        return -EFAULT;
2739}
2740EXPORT_SYMBOL(skb_store_bits);
2741
2742/* Checksum skb data. */
2743__wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
2744                      __wsum csum, const struct skb_checksum_ops *ops)
2745{
2746        int start = skb_headlen(skb);
2747        int i, copy = start - offset;
2748        struct sk_buff *frag_iter;
2749        int pos = 0;
2750
2751        /* Checksum header. */
2752        if (copy > 0) {
2753                if (copy > len)
2754                        copy = len;
2755                csum = INDIRECT_CALL_1(ops->update, csum_partial_ext,
2756                                       skb->data + offset, copy, csum);
2757                if ((len -= copy) == 0)
2758                        return csum;
2759                offset += copy;
2760                pos     = copy;
2761        }
2762
2763        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2764                int end;
2765                skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2766
2767                WARN_ON(start > offset + len);
2768
2769                end = start + skb_frag_size(frag);
2770                if ((copy = end - offset) > 0) {
2771                        u32 p_off, p_len, copied;
2772                        struct page *p;
2773                        __wsum csum2;
2774                        u8 *vaddr;
2775
2776                        if (copy > len)
2777                                copy = len;
2778
2779                        skb_frag_foreach_page(frag,
2780                                              skb_frag_off(frag) + offset - start,
2781                                              copy, p, p_off, p_len, copied) {
2782                                vaddr = kmap_atomic(p);
2783                                csum2 = INDIRECT_CALL_1(ops->update,
2784                                                        csum_partial_ext,
2785                                                        vaddr + p_off, p_len, 0);
2786                                kunmap_atomic(vaddr);
2787                                csum = INDIRECT_CALL_1(ops->combine,
2788                                                       csum_block_add_ext, csum,
2789                                                       csum2, pos, p_len);
2790                                pos += p_len;
2791                        }
2792
2793                        if (!(len -= copy))
2794                                return csum;
2795                        offset += copy;
2796                }
2797                start = end;
2798        }
2799
2800        skb_walk_frags(skb, frag_iter) {
2801                int end;
2802
2803                WARN_ON(start > offset + len);
2804
2805                end = start + frag_iter->len;
2806                if ((copy = end - offset) > 0) {
2807                        __wsum csum2;
2808                        if (copy > len)
2809                                copy = len;
2810                        csum2 = __skb_checksum(frag_iter, offset - start,
2811                                               copy, 0, ops);
2812                        csum = INDIRECT_CALL_1(ops->combine, csum_block_add_ext,
2813                                               csum, csum2, pos, copy);
2814                        if ((len -= copy) == 0)
2815                                return csum;
2816                        offset += copy;
2817                        pos    += copy;
2818                }
2819                start = end;
2820        }
2821        BUG_ON(len);
2822
2823        return csum;
2824}
2825EXPORT_SYMBOL(__skb_checksum);
2826
2827__wsum skb_checksum(const struct sk_buff *skb, int offset,
2828                    int len, __wsum csum)
2829{
2830        const struct skb_checksum_ops ops = {
2831                .update  = csum_partial_ext,
2832                .combine = csum_block_add_ext,
2833        };
2834
2835        return __skb_checksum(skb, offset, len, csum, &ops);
2836}
2837EXPORT_SYMBOL(skb_checksum);
2838
2839/* Both of above in one bottle. */
2840
2841__wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
2842                                    u8 *to, int len)
2843{
2844        int start = skb_headlen(skb);
2845        int i, copy = start - offset;
2846        struct sk_buff *frag_iter;
2847        int pos = 0;
2848        __wsum csum = 0;
2849
2850        /* Copy header. */
2851        if (copy > 0) {
2852                if (copy > len)
2853                        copy = len;
2854                csum = csum_partial_copy_nocheck(skb->data + offset, to,
2855                                                 copy);
2856                if ((len -= copy) == 0)
2857                        return csum;
2858                offset += copy;
2859                to     += copy;
2860                pos     = copy;
2861        }
2862
2863        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2864                int end;
2865
2866                WARN_ON(start > offset + len);
2867
2868                end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
2869                if ((copy = end - offset) > 0) {
2870                        skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2871                        u32 p_off, p_len, copied;
2872                        struct page *p;
2873                        __wsum csum2;
2874                        u8 *vaddr;
2875
2876                        if (copy > len)
2877                                copy = len;
2878
2879                        skb_frag_foreach_page(frag,
2880                                              skb_frag_off(frag) + offset - start,
2881                                              copy, p, p_off, p_len, copied) {
2882                                vaddr = kmap_atomic(p);
2883                                csum2 = csum_partial_copy_nocheck(vaddr + p_off,
2884                                                                  to + copied,
2885                                                                  p_len);
2886                                kunmap_atomic(vaddr);
2887                                csum = csum_block_add(csum, csum2, pos);
2888                                pos += p_len;
2889                        }
2890
2891                        if (!(len -= copy))
2892                                return csum;
2893                        offset += copy;
2894                        to     += copy;
2895                }
2896                start = end;
2897        }
2898
2899        skb_walk_frags(skb, frag_iter) {
2900                __wsum csum2;
2901                int end;
2902
2903                WARN_ON(start > offset + len);
2904
2905                end = start + frag_iter->len;
2906                if ((copy = end - offset) > 0) {
2907                        if (copy > len)
2908                                copy = len;
2909                        csum2 = skb_copy_and_csum_bits(frag_iter,
2910                                                       offset - start,
2911                                                       to, copy);
2912                        csum = csum_block_add(csum, csum2, pos);
2913                        if ((len -= copy) == 0)
2914                                return csum;
2915                        offset += copy;
2916                        to     += copy;
2917                        pos    += copy;
2918                }
2919                start = end;
2920        }
2921        BUG_ON(len);
2922        return csum;
2923}
2924EXPORT_SYMBOL(skb_copy_and_csum_bits);
2925
2926__sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
2927{
2928        __sum16 sum;
2929
2930        sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
2931        /* See comments in __skb_checksum_complete(). */
2932        if (likely(!sum)) {
2933                if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
2934                    !skb->csum_complete_sw)
2935                        netdev_rx_csum_fault(skb->dev, skb);
2936        }
2937        if (!skb_shared(skb))
2938                skb->csum_valid = !sum;
2939        return sum;
2940}
2941EXPORT_SYMBOL(__skb_checksum_complete_head);
2942
2943/* This function assumes skb->csum already holds pseudo header's checksum,
2944 * which has been changed from the hardware checksum, for example, by
2945 * __skb_checksum_validate_complete(). And, the original skb->csum must
2946 * have been validated unsuccessfully for CHECKSUM_COMPLETE case.
2947 *
2948 * It returns non-zero if the recomputed checksum is still invalid, otherwise
2949 * zero. The new checksum is stored back into skb->csum unless the skb is
2950 * shared.
2951 */
2952__sum16 __skb_checksum_complete(struct sk_buff *skb)
2953{
2954        __wsum csum;
2955        __sum16 sum;
2956
2957        csum = skb_checksum(skb, 0, skb->len, 0);
2958
2959        sum = csum_fold(csum_add(skb->csum, csum));
2960        /* This check is inverted, because we already knew the hardware
2961         * checksum is invalid before calling this function. So, if the
2962         * re-computed checksum is valid instead, then we have a mismatch
2963         * between the original skb->csum and skb_checksum(). This means either
2964         * the original hardware checksum is incorrect or we screw up skb->csum
2965         * when moving skb->data around.
2966         */
2967        if (likely(!sum)) {
2968                if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
2969                    !skb->csum_complete_sw)
2970                        netdev_rx_csum_fault(skb->dev, skb);
2971        }
2972
2973        if (!skb_shared(skb)) {
2974                /* Save full packet checksum */
2975                skb->csum = csum;
2976                skb->ip_summed = CHECKSUM_COMPLETE;
2977                skb->csum_complete_sw = 1;
2978                skb->csum_valid = !sum;
2979        }
2980
2981        return sum;
2982}
2983EXPORT_SYMBOL(__skb_checksum_complete);
2984
2985static __wsum warn_crc32c_csum_update(const void *buff, int len, __wsum sum)
2986{
2987        net_warn_ratelimited(
2988                "%s: attempt to compute crc32c without libcrc32c.ko\n",
2989                __func__);
2990        return 0;
2991}
2992
2993static __wsum warn_crc32c_csum_combine(__wsum csum, __wsum csum2,
2994                                       int offset, int len)
2995{
2996        net_warn_ratelimited(
2997                "%s: attempt to compute crc32c without libcrc32c.ko\n",
2998                __func__);
2999        return 0;
3000}
3001
3002static const struct skb_checksum_ops default_crc32c_ops = {
3003        .update  = warn_crc32c_csum_update,
3004        .combine = warn_crc32c_csum_combine,
3005};
3006
3007const struct skb_checksum_ops *crc32c_csum_stub __read_mostly =
3008        &default_crc32c_ops;
3009EXPORT_SYMBOL(crc32c_csum_stub);
3010
3011 /**
3012 *      skb_zerocopy_headlen - Calculate headroom needed for skb_zerocopy()
3013 *      @from: source buffer
3014 *
3015 *      Calculates the amount of linear headroom needed in the 'to' skb passed
3016 *      into skb_zerocopy().
3017 */
3018unsigned int
3019skb_zerocopy_headlen(const struct sk_buff *from)
3020{
3021        unsigned int hlen = 0;
3022
3023        if (!from->head_frag ||
3024            skb_headlen(from) < L1_CACHE_BYTES ||
3025            skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS) {
3026                hlen = skb_headlen(from);
3027                if (!hlen)
3028                        hlen = from->len;
3029        }
3030
3031        if (skb_has_frag_list(from))
3032                hlen = from->len;
3033
3034        return hlen;
3035}
3036EXPORT_SYMBOL_GPL(skb_zerocopy_headlen);
3037
3038/**
3039 *      skb_zerocopy - Zero copy skb to skb
3040 *      @to: destination buffer
3041 *      @from: source buffer
3042 *      @len: number of bytes to copy from source buffer
3043 *      @hlen: size of linear headroom in destination buffer
3044 *
3045 *      Copies up to `len` bytes from `from` to `to` by creating references
3046 *      to the frags in the source buffer.
3047 *
3048 *      The `hlen` as calculated by skb_zerocopy_headlen() specifies the
3049 *      headroom in the `to` buffer.
3050 *
3051 *      Return value:
3052 *      0: everything is OK
3053 *      -ENOMEM: couldn't orphan frags of @from due to lack of memory
3054 *      -EFAULT: skb_copy_bits() found some problem with skb geometry
3055 */
3056int
3057skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen)
3058{
3059        int i, j = 0;
3060        int plen = 0; /* length of skb->head fragment */
3061        int ret;
3062        struct page *page;
3063        unsigned int offset;
3064
3065        BUG_ON(!from->head_frag && !hlen);
3066
3067        /* dont bother with small payloads */
3068        if (len <= skb_tailroom(to))
3069                return skb_copy_bits(from, 0, skb_put(to, len), len);
3070
3071        if (hlen) {
3072                ret = skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
3073                if (unlikely(ret))
3074                        return ret;
3075                len -= hlen;
3076        } else {
3077                plen = min_t(int, skb_headlen(from), len);
3078                if (plen) {
3079                        page = virt_to_head_page(from->head);
3080                        offset = from->data - (unsigned char *)page_address(page);
3081                        __skb_fill_page_desc(to, 0, page, offset, plen);
3082                        get_page(page);
3083                        j = 1;
3084                        len -= plen;
3085                }
3086        }
3087
3088        to->truesize += len + plen;
3089        to->len += len + plen;
3090        to->data_len += len + plen;
3091
3092        if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) {
3093                skb_tx_error(from);
3094                return -ENOMEM;
3095        }
3096        skb_zerocopy_clone(to, from, GFP_ATOMIC);
3097
3098        for (i = 0; i < skb_shinfo(from)->nr_frags; i++) {
3099                int size;
3100
3101                if (!len)
3102                        break;
3103                skb_shinfo(to)->frags[j] = skb_shinfo(from)->frags[i];
3104                size = min_t(int, skb_frag_size(&skb_shinfo(to)->frags[j]),
3105                                        len);
3106                skb_frag_size_set(&skb_shinfo(to)->frags[j], size);
3107                len -= size;
3108                skb_frag_ref(to, j);
3109                j++;
3110        }
3111        skb_shinfo(to)->nr_frags = j;
3112
3113        return 0;
3114}
3115EXPORT_SYMBOL_GPL(skb_zerocopy);
3116
3117void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
3118{
3119        __wsum csum;
3120        long csstart;
3121
3122        if (skb->ip_summed == CHECKSUM_PARTIAL)
3123                csstart = skb_checksum_start_offset(skb);
3124        else
3125                csstart = skb_headlen(skb);
3126
3127        BUG_ON(csstart > skb_headlen(skb));
3128
3129        skb_copy_from_linear_data(skb, to, csstart);
3130
3131        csum = 0;
3132        if (csstart != skb->len)
3133                csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
3134                                              skb->len - csstart);
3135
3136        if (skb->ip_summed == CHECKSUM_PARTIAL) {
3137                long csstuff = csstart + skb->csum_offset;
3138
3139                *((__sum16 *)(to + csstuff)) = csum_fold(csum);
3140        }
3141}
3142EXPORT_SYMBOL(skb_copy_and_csum_dev);
3143
3144/**
3145 *      skb_dequeue - remove from the head of the queue
3146 *      @list: list to dequeue from
3147 *
3148 *      Remove the head of the list. The list lock is taken so the function
3149 *      may be used safely with other locking list functions. The head item is
3150 *      returned or %NULL if the list is empty.
3151 */
3152
3153struct sk_buff *skb_dequeue(struct sk_buff_head *list)
3154{
3155        unsigned long flags;
3156        struct sk_buff *result;
3157
3158        spin_lock_irqsave(&list->lock, flags);
3159        result = __skb_dequeue(list);
3160        spin_unlock_irqrestore(&list->lock, flags);
3161        return result;
3162}
3163EXPORT_SYMBOL(skb_dequeue);
3164
3165/**
3166 *      skb_dequeue_tail - remove from the tail of the queue
3167 *      @list: list to dequeue from
3168 *
3169 *      Remove the tail of the list. The list lock is taken so the function
3170 *      may be used safely with other locking list functions. The tail item is
3171 *      returned or %NULL if the list is empty.
3172 */
3173struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
3174{
3175        unsigned long flags;
3176        struct sk_buff *result;
3177
3178        spin_lock_irqsave(&list->lock, flags);
3179        result = __skb_dequeue_tail(list);
3180        spin_unlock_irqrestore(&list->lock, flags);
3181        return result;
3182}
3183EXPORT_SYMBOL(skb_dequeue_tail);
3184
3185/**
3186 *      skb_queue_purge - empty a list
3187 *      @list: list to empty
3188 *
3189 *      Delete all buffers on an &sk_buff list. Each buffer is removed from
3190 *      the list and one reference dropped. This function takes the list
3191 *      lock and is atomic with respect to other list locking functions.
3192 */
3193void skb_queue_purge(struct sk_buff_head *list)
3194{
3195        struct sk_buff *skb;
3196        while ((skb = skb_dequeue(list)) != NULL)
3197                kfree_skb(skb);
3198}
3199EXPORT_SYMBOL(skb_queue_purge);
3200
3201/**
3202 *      skb_rbtree_purge - empty a skb rbtree
3203 *      @root: root of the rbtree to empty
3204 *      Return value: the sum of truesizes of all purged skbs.
3205 *
3206 *      Delete all buffers on an &sk_buff rbtree. Each buffer is removed from
3207 *      the list and one reference dropped. This function does not take
3208 *      any lock. Synchronization should be handled by the caller (e.g., TCP
3209 *      out-of-order queue is protected by the socket lock).
3210 */
3211unsigned int skb_rbtree_purge(struct rb_root *root)
3212{
3213        struct rb_node *p = rb_first(root);
3214        unsigned int sum = 0;
3215
3216        while (p) {
3217                struct sk_buff *skb = rb_entry(p, struct sk_buff, rbnode);
3218
3219                p = rb_next(p);
3220                rb_erase(&skb->rbnode, root);
3221                sum += skb->truesize;
3222                kfree_skb(skb);
3223        }
3224        return sum;
3225}
3226
3227/**
3228 *      skb_queue_head - queue a buffer at the list head
3229 *      @list: list to use
3230 *      @newsk: buffer to queue
3231 *
3232 *      Queue a buffer at the start of the list. This function takes the
3233 *      list lock and can be used safely with other locking &sk_buff functions
3234 *      safely.
3235 *
3236 *      A buffer cannot be placed on two lists at the same time.
3237 */
3238void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
3239{
3240        unsigned long flags;
3241
3242        spin_lock_irqsave(&list->lock, flags);
3243        __skb_queue_head(list, newsk);
3244        spin_unlock_irqrestore(&list->lock, flags);
3245}
3246EXPORT_SYMBOL(skb_queue_head);
3247
3248/**
3249 *      skb_queue_tail - queue a buffer at the list tail
3250 *      @list: list to use
3251 *      @newsk: buffer to queue
3252 *
3253 *      Queue a buffer at the tail of the list. This function takes the
3254 *      list lock and can be used safely with other locking &sk_buff functions
3255 *      safely.
3256 *
3257 *      A buffer cannot be placed on two lists at the same time.
3258 */
3259void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
3260{
3261        unsigned long flags;
3262
3263        spin_lock_irqsave(&list->lock, flags);
3264        __skb_queue_tail(list, newsk);
3265        spin_unlock_irqrestore(&list->lock, flags);
3266}
3267EXPORT_SYMBOL(skb_queue_tail);
3268
3269/**
3270 *      skb_unlink      -       remove a buffer from a list
3271 *      @skb: buffer to remove
3272 *      @list: list to use
3273 *
3274 *      Remove a packet from a list. The list locks are taken and this
3275 *      function is atomic with respect to other list locked calls
3276 *
3277 *      You must know what list the SKB is on.
3278 */
3279void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
3280{
3281        unsigned long flags;
3282
3283        spin_lock_irqsave(&list->lock, flags);
3284        __skb_unlink(skb, list);
3285        spin_unlock_irqrestore(&list->lock, flags);
3286}
3287EXPORT_SYMBOL(skb_unlink);
3288
3289/**
3290 *      skb_append      -       append a buffer
3291 *      @old: buffer to insert after
3292 *      @newsk: buffer to insert
3293 *      @list: list to use
3294 *
3295 *      Place a packet after a given packet in a list. The list locks are taken
3296 *      and this function is atomic with respect to other list locked calls.
3297 *      A buffer cannot be placed on two lists at the same time.
3298 */
3299void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
3300{
3301        unsigned long flags;
3302
3303        spin_lock_irqsave(&list->lock, flags);
3304        __skb_queue_after(list, old, newsk);
3305        spin_unlock_irqrestore(&list->lock, flags);
3306}
3307EXPORT_SYMBOL(skb_append);
3308
3309static inline void skb_split_inside_header(struct sk_buff *skb,
3310                                           struct sk_buff* skb1,
3311                                           const u32 len, const int pos)
3312{
3313        int i;
3314
3315        skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
3316                                         pos - len);
3317        /* And move data appendix as is. */
3318        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
3319                skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
3320
3321        skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
3322        skb_shinfo(skb)->nr_frags  = 0;
3323        skb1->data_len             = skb->data_len;
3324        skb1->len                  += skb1->data_len;
3325        skb->data_len              = 0;
3326        skb->len                   = len;
3327        skb_set_tail_pointer(skb, len);
3328}
3329
3330static inline void skb_split_no_header(struct sk_buff *skb,
3331                                       struct sk_buff* skb1,
3332                                       const u32 len, int pos)
3333{
3334        int i, k = 0;
3335        const int nfrags = skb_shinfo(skb)->nr_frags;
3336
3337        skb_shinfo(skb)->nr_frags = 0;
3338        skb1->len                 = skb1->data_len = skb->len - len;
3339        skb->len                  = len;
3340        skb->data_len             = len - pos;
3341
3342        for (i = 0; i < nfrags; i++) {
3343                int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
3344
3345                if (pos + size > len) {
3346                        skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
3347
3348                        if (pos < len) {
3349                                /* Split frag.
3350                                 * We have two variants in this case:
3351                                 * 1. Move all the frag to the second
3352                                 *    part, if it is possible. F.e.
3353                                 *    this approach is mandatory for TUX,
3354                                 *    where splitting is expensive.
3355                                 * 2. Split is accurately. We make this.
3356                                 */
3357                                skb_frag_ref(skb, i);
3358                                skb_frag_off_add(&skb_shinfo(skb1)->frags[0], len - pos);
3359                                skb_frag_size_sub(&skb_shinfo(skb1)->frags[0], len - pos);
3360                                skb_frag_size_set(&skb_shinfo(skb)->frags[i], len - pos);
3361                                skb_shinfo(skb)->nr_frags++;
3362                        }
3363                        k++;
3364                } else
3365                        skb_shinfo(skb)->nr_frags++;
3366                pos += size;
3367        }
3368        skb_shinfo(skb1)->nr_frags = k;
3369}
3370
3371/**
3372 * skb_split - Split fragmented skb to two parts at length len.
3373 * @skb: the buffer to split
3374 * @skb1: the buffer to receive the second part
3375 * @len: new length for skb
3376 */
3377void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
3378{
3379        int pos = skb_headlen(skb);
3380
3381        skb_shinfo(skb1)->flags |= skb_shinfo(skb)->flags & SKBFL_SHARED_FRAG;
3382        skb_zerocopy_clone(skb1, skb, 0);
3383        if (len < pos)  /* Split line is inside header. */
3384                skb_split_inside_header(skb, skb1, len, pos);
3385        else            /* Second chunk has no header, nothing to copy. */
3386                skb_split_no_header(skb, skb1, len, pos);
3387}
3388EXPORT_SYMBOL(skb_split);
3389
3390/* Shifting from/to a cloned skb is a no-go.
3391 *
3392 * Caller cannot keep skb_shinfo related pointers past calling here!
3393 */
3394static int skb_prepare_for_shift(struct sk_buff *skb)
3395{
3396        int ret = 0;
3397
3398        if (skb_cloned(skb)) {
3399                /* Save and restore truesize: pskb_expand_head() may reallocate
3400                 * memory where ksize(kmalloc(S)) != ksize(kmalloc(S)), but we
3401                 * cannot change truesize at this point.
3402                 */
3403                unsigned int save_truesize = skb->truesize;
3404
3405                ret = pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
3406                skb->truesize = save_truesize;
3407        }
3408        return ret;
3409}
3410
3411/**
3412 * skb_shift - Shifts paged data partially from skb to another
3413 * @tgt: buffer into which tail data gets added
3414 * @skb: buffer from which the paged data comes from
3415 * @shiftlen: shift up to this many bytes
3416 *
3417 * Attempts to shift up to shiftlen worth of bytes, which may be less than
3418 * the length of the skb, from skb to tgt. Returns number bytes shifted.
3419 * It's up to caller to free skb if everything was shifted.
3420 *
3421 * If @tgt runs out of frags, the whole operation is aborted.
3422 *
3423 * Skb cannot include anything else but paged data while tgt is allowed
3424 * to have non-paged data as well.
3425 *
3426 * TODO: full sized shift could be optimized but that would need
3427 * specialized skb free'er to handle frags without up-to-date nr_frags.
3428 */
3429int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
3430{
3431        int from, to, merge, todo;
3432        skb_frag_t *fragfrom, *fragto;
3433
3434        BUG_ON(shiftlen > skb->len);
3435
3436        if (skb_headlen(skb))
3437                return 0;
3438        if (skb_zcopy(tgt) || skb_zcopy(skb))
3439                return 0;
3440
3441        todo = shiftlen;
3442        from = 0;
3443        to = skb_shinfo(tgt)->nr_frags;
3444        fragfrom = &skb_shinfo(skb)->frags[from];
3445
3446        /* Actual merge is delayed until the point when we know we can
3447         * commit all, so that we don't have to undo partial changes
3448         */
3449        if (!to ||
3450            !skb_can_coalesce(tgt, to, skb_frag_page(fragfrom),
3451                              skb_frag_off(fragfrom))) {
3452                merge = -1;
3453        } else {
3454                merge = to - 1;
3455
3456                todo -= skb_frag_size(fragfrom);
3457                if (todo < 0) {
3458                        if (skb_prepare_for_shift(skb) ||
3459                            skb_prepare_for_shift(tgt))
3460                                return 0;
3461
3462                        /* All previous frag pointers might be stale! */
3463                        fragfrom = &skb_shinfo(skb)->frags[from];
3464                        fragto = &skb_shinfo(tgt)->frags[merge];
3465
3466                        skb_frag_size_add(fragto, shiftlen);
3467                        skb_frag_size_sub(fragfrom, shiftlen);
3468                        skb_frag_off_add(fragfrom, shiftlen);
3469
3470                        goto onlymerged;
3471                }
3472
3473                from++;
3474        }
3475
3476        /* Skip full, not-fitting skb to avoid expensive operations */
3477        if ((shiftlen == skb->len) &&
3478            (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
3479                return 0;
3480
3481        if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
3482                return 0;
3483
3484        while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
3485                if (to == MAX_SKB_FRAGS)
3486                        return 0;
3487
3488                fragfrom = &skb_shinfo(skb)->frags[from];
3489                fragto = &skb_shinfo(tgt)->frags[to];
3490
3491                if (todo >= skb_frag_size(fragfrom)) {
3492                        *fragto = *fragfrom;
3493                        todo -= skb_frag_size(fragfrom);
3494                        from++;
3495                        to++;
3496
3497                } else {
3498                        __skb_frag_ref(fragfrom);
3499                        skb_frag_page_copy(fragto, fragfrom);
3500                        skb_frag_off_copy(fragto, fragfrom);
3501                        skb_frag_size_set(fragto, todo);
3502
3503                        skb_frag_off_add(fragfrom, todo);
3504                        skb_frag_size_sub(fragfrom, todo);
3505                        todo = 0;
3506
3507                        to++;
3508                        break;
3509                }
3510        }
3511
3512        /* Ready to "commit" this state change to tgt */
3513        skb_shinfo(tgt)->nr_frags = to;
3514
3515        if (merge >= 0) {
3516                fragfrom = &skb_shinfo(skb)->frags[0];
3517                fragto = &skb_shinfo(tgt)->frags[merge];
3518
3519                skb_frag_size_add(fragto, skb_frag_size(fragfrom));
3520                __skb_frag_unref(fragfrom, skb->pp_recycle);
3521        }
3522
3523        /* Reposition in the original skb */
3524        to = 0;
3525        while (from < skb_shinfo(skb)->nr_frags)
3526                skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
3527        skb_shinfo(skb)->nr_frags = to;
3528
3529        BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);
3530
3531onlymerged:
3532        /* Most likely the tgt won't ever need its checksum anymore, skb on
3533         * the other hand might need it if it needs to be resent
3534         */
3535        tgt->ip_summed = CHECKSUM_PARTIAL;
3536        skb->ip_summed = CHECKSUM_PARTIAL;
3537
3538        /* Yak, is it really working this way? Some helper please? */
3539        skb->len -= shiftlen;
3540        skb->data_len -= shiftlen;
3541        skb->truesize -= shiftlen;
3542        tgt->len += shiftlen;
3543        tgt->data_len += shiftlen;
3544        tgt->truesize += shiftlen;
3545
3546        return shiftlen;
3547}
3548
3549/**
3550 * skb_prepare_seq_read - Prepare a sequential read of skb data
3551 * @skb: the buffer to read
3552 * @from: lower offset of data to be read
3553 * @to: upper offset of data to be read
3554 * @st: state variable
3555 *
3556 * Initializes the specified state variable. Must be called before
3557 * invoking skb_seq_read() for the first time.
3558 */
3559void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
3560                          unsigned int to, struct skb_seq_state *st)
3561{
3562        st->lower_offset = from;
3563        st->upper_offset = to;
3564        st->root_skb = st->cur_skb = skb;
3565        st->frag_idx = st->stepped_offset = 0;
3566        st->frag_data = NULL;
3567        st->frag_off = 0;
3568}
3569EXPORT_SYMBOL(skb_prepare_seq_read);
3570
3571/**
3572 * skb_seq_read - Sequentially read skb data
3573 * @consumed: number of bytes consumed by the caller so far
3574 * @data: destination pointer for data to be returned
3575 * @st: state variable
3576 *
3577 * Reads a block of skb data at @consumed relative to the
3578 * lower offset specified to skb_prepare_seq_read(). Assigns
3579 * the head of the data block to @data and returns the length
3580 * of the block or 0 if the end of the skb data or the upper
3581 * offset has been reached.
3582 *
3583 * The caller is not required to consume all of the data
3584 * returned, i.e. @consumed is typically set to the number
3585 * of bytes already consumed and the next call to
3586 * skb_seq_read() will return the remaining part of the block.
3587 *
3588 * Note 1: The size of each block of data returned can be arbitrary,
3589 *       this limitation is the cost for zerocopy sequential
3590 *       reads of potentially non linear data.
3591 *
3592 * Note 2: Fragment lists within fragments are not implemented
3593 *       at the moment, state->root_skb could be replaced with
3594 *       a stack for this purpose.
3595 */
3596unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
3597                          struct skb_seq_state *st)
3598{
3599        unsigned int block_limit, abs_offset = consumed + st->lower_offset;
3600        skb_frag_t *frag;
3601
3602        if (unlikely(abs_offset >= st->upper_offset)) {
3603                if (st->frag_data) {
3604                        kunmap_atomic(st->frag_data);
3605                        st->frag_data = NULL;
3606                }
3607                return 0;
3608        }
3609
3610next_skb:
3611        block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
3612
3613        if (abs_offset < block_limit && !st->frag_data) {
3614                *data = st->cur_skb->data + (abs_offset - st->stepped_offset);
3615                return block_limit - abs_offset;
3616        }
3617
3618        if (st->frag_idx == 0 && !st->frag_data)
3619                st->stepped_offset += skb_headlen(st->cur_skb);
3620
3621        while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
3622                unsigned int pg_idx, pg_off, pg_sz;
3623
3624                frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
3625
3626                pg_idx = 0;
3627                pg_off = skb_frag_off(frag);
3628                pg_sz = skb_frag_size(frag);
3629
3630                if (skb_frag_must_loop(skb_frag_page(frag))) {
3631                        pg_idx = (pg_off + st->frag_off) >> PAGE_SHIFT;
3632                        pg_off = offset_in_page(pg_off + st->frag_off);
3633                        pg_sz = min_t(unsigned int, pg_sz - st->frag_off,
3634                                                    PAGE_SIZE - pg_off);
3635                }
3636
3637                block_limit = pg_sz + st->stepped_offset;
3638                if (abs_offset < block_limit) {
3639                        if (!st->frag_data)
3640                                st->frag_data = kmap_atomic(skb_frag_page(frag) + pg_idx);
3641
3642                        *data = (u8 *)st->frag_data + pg_off +
3643                                (abs_offset - st->stepped_offset);
3644
3645                        return block_limit - abs_offset;
3646                }
3647
3648                if (st->frag_data) {
3649                        kunmap_atomic(st->frag_data);
3650                        st->frag_data = NULL;
3651                }
3652
3653                st->stepped_offset += pg_sz;
3654                st->frag_off += pg_sz;
3655                if (st->frag_off == skb_frag_size(frag)) {
3656                        st->frag_off = 0;
3657                        st->frag_idx++;
3658                }
3659        }
3660
3661        if (st->frag_data) {
3662                kunmap_atomic(st->frag_data);
3663                st->frag_data = NULL;
3664        }
3665
3666        if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
3667                st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
3668                st->frag_idx = 0;
3669                goto next_skb;
3670        } else if (st->cur_skb->next) {
3671                st->cur_skb = st->cur_skb->next;
3672                st->frag_idx = 0;
3673                goto next_skb;
3674        }
3675
3676        return 0;
3677}
3678EXPORT_SYMBOL(skb_seq_read);
3679
3680/**
3681 * skb_abort_seq_read - Abort a sequential read of skb data
3682 * @st: state variable
3683 *
3684 * Must be called if skb_seq_read() was not called until it
3685 * returned 0.
3686 */
3687void skb_abort_seq_read(struct skb_seq_state *st)
3688{
3689        if (st->frag_data)
3690                kunmap_atomic(st->frag_data);
3691}
3692EXPORT_SYMBOL(skb_abort_seq_read);
3693
3694#define TS_SKB_CB(state)        ((struct skb_seq_state *) &((state)->cb))
3695
3696static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
3697                                          struct ts_config *conf,
3698                                          struct ts_state *state)
3699{
3700        return skb_seq_read(offset, text, TS_SKB_CB(state));
3701}
3702
3703static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
3704{
3705        skb_abort_seq_read(TS_SKB_CB(state));
3706}
3707
3708/**
3709 * skb_find_text - Find a text pattern in skb data
3710 * @skb: the buffer to look in
3711 * @from: search offset
3712 * @to: search limit
3713 * @config: textsearch configuration
3714 *
3715 * Finds a pattern in the skb data according to the specified
3716 * textsearch configuration. Use textsearch_next() to retrieve
3717 * subsequent occurrences of the pattern. Returns the offset
3718 * to the first occurrence or UINT_MAX if no match was found.
3719 */
3720unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
3721                           unsigned int to, struct ts_config *config)
3722{
3723        struct ts_state state;
3724        unsigned int ret;
3725
3726        BUILD_BUG_ON(sizeof(struct skb_seq_state) > sizeof(state.cb));
3727
3728        config->get_next_block = skb_ts_get_next_block;
3729        config->finish = skb_ts_finish;
3730
3731        skb_prepare_seq_read(skb, from, to, TS_SKB_CB(&state));
3732
3733        ret = textsearch_find(config, &state);
3734        return (ret <= to - from ? ret : UINT_MAX);
3735}
3736EXPORT_SYMBOL(skb_find_text);
3737
3738int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
3739                         int offset, size_t size)
3740{
3741        int i = skb_shinfo(skb)->nr_frags;
3742
3743        if (skb_can_coalesce(skb, i, page, offset)) {
3744                skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
3745        } else if (i < MAX_SKB_FRAGS) {
3746                get_page(page);
3747                skb_fill_page_desc(skb, i, page, offset, size);
3748        } else {
3749                return -EMSGSIZE;
3750        }
3751
3752        return 0;
3753}
3754EXPORT_SYMBOL_GPL(skb_append_pagefrags);
3755
3756/**
3757 *      skb_pull_rcsum - pull skb and update receive checksum
3758 *      @skb: buffer to update
3759 *      @len: length of data pulled
3760 *
3761 *      This function performs an skb_pull on the packet and updates
3762 *      the CHECKSUM_COMPLETE checksum.  It should be used on
3763 *      receive path processing instead of skb_pull unless you know
3764 *      that the checksum difference is zero (e.g., a valid IP header)
3765 *      or you are setting ip_summed to CHECKSUM_NONE.
3766 */
3767void *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
3768{
3769        unsigned char *data = skb->data;
3770
3771        BUG_ON(len > skb->len);
3772        __skb_pull(skb, len);
3773        skb_postpull_rcsum(skb, data, len);
3774        return skb->data;
3775}
3776EXPORT_SYMBOL_GPL(skb_pull_rcsum);
3777
3778static inline skb_frag_t skb_head_frag_to_page_desc(struct sk_buff *frag_skb)
3779{
3780        skb_frag_t head_frag;
3781        struct page *page;
3782
3783        page = virt_to_head_page(frag_skb->head);
3784        __skb_frag_set_page(&head_frag, page);
3785        skb_frag_off_set(&head_frag, frag_skb->data -
3786                         (unsigned char *)page_address(page));
3787        skb_frag_size_set(&head_frag, skb_headlen(frag_skb));
3788        return head_frag;
3789}
3790
3791struct sk_buff *skb_segment_list(struct sk_buff *skb,
3792                                 netdev_features_t features,
3793                                 unsigned int offset)
3794{
3795        struct sk_buff *list_skb = skb_shinfo(skb)->frag_list;
3796        unsigned int tnl_hlen = skb_tnl_header_len(skb);
3797        unsigned int delta_truesize = 0;
3798        unsigned int delta_len = 0;
3799        struct sk_buff *tail = NULL;
3800        struct sk_buff *nskb, *tmp;
3801        int err;
3802
3803        skb_push(skb, -skb_network_offset(skb) + offset);
3804
3805        skb_shinfo(skb)->frag_list = NULL;
3806
3807        do {
3808                nskb = list_skb;
3809                list_skb = list_skb->next;
3810
3811                err = 0;
3812                if (skb_shared(nskb)) {
3813                        tmp = skb_clone(nskb, GFP_ATOMIC);
3814                        if (tmp) {
3815                                consume_skb(nskb);
3816                                nskb = tmp;
3817                                err = skb_unclone(nskb, GFP_ATOMIC);
3818                        } else {
3819                                err = -ENOMEM;
3820                        }
3821                }
3822
3823                if (!tail)
3824                        skb->next = nskb;
3825                else
3826                        tail->next = nskb;
3827
3828                if (unlikely(err)) {
3829                        nskb->next = list_skb;
3830                        goto err_linearize;
3831                }
3832
3833                tail = nskb;
3834
3835                delta_len += nskb->len;
3836                delta_truesize += nskb->truesize;
3837
3838                skb_push(nskb, -skb_network_offset(nskb) + offset);
3839
3840                skb_release_head_state(nskb);
3841                 __copy_skb_header(nskb, skb);
3842
3843                skb_headers_offset_update(nskb, skb_headroom(nskb) - skb_headroom(skb));
3844                skb_copy_from_linear_data_offset(skb, -tnl_hlen,
3845                                                 nskb->data - tnl_hlen,
3846                                                 offset + tnl_hlen);
3847
3848                if (skb_needs_linearize(nskb, features) &&
3849                    __skb_linearize(nskb))
3850                        goto err_linearize;
3851
3852        } while (list_skb);
3853
3854        skb->truesize = skb->truesize - delta_truesize;
3855        skb->data_len = skb->data_len - delta_len;
3856        skb->len = skb->len - delta_len;
3857
3858        skb_gso_reset(skb);
3859
3860        skb->prev = tail;
3861
3862        if (skb_needs_linearize(skb, features) &&
3863            __skb_linearize(skb))
3864                goto err_linearize;
3865
3866        skb_get(skb);
3867
3868        return skb;
3869
3870err_linearize:
3871        kfree_skb_list(skb->next);
3872        skb->next = NULL;
3873        return ERR_PTR(-ENOMEM);
3874}
3875EXPORT_SYMBOL_GPL(skb_segment_list);
3876
3877int skb_gro_receive_list(struct sk_buff *p, struct sk_buff *skb)
3878{
3879        if (unlikely(p->len + skb->len >= 65536))
3880                return -E2BIG;
3881
3882        if (NAPI_GRO_CB(p)->last == p)
3883                skb_shinfo(p)->frag_list = skb;
3884        else
3885                NAPI_GRO_CB(p)->last->next = skb;
3886
3887        skb_pull(skb, skb_gro_offset(skb));
3888
3889        NAPI_GRO_CB(p)->last = skb;
3890        NAPI_GRO_CB(p)->count++;
3891        p->data_len += skb->len;
3892        p->truesize += skb->truesize;
3893        p->len += skb->len;
3894
3895        NAPI_GRO_CB(skb)->same_flow = 1;
3896
3897        return 0;
3898}
3899
3900/**
3901 *      skb_segment - Perform protocol segmentation on skb.
3902 *      @head_skb: buffer to segment
3903 *      @features: features for the output path (see dev->features)
3904 *
3905 *      This function performs segmentation on the given skb.  It returns
3906 *      a pointer to the first in a list of new skbs for the segments.
3907 *      In case of error it returns ERR_PTR(err).
3908 */
3909struct sk_buff *skb_segment(struct sk_buff *head_skb,
3910                            netdev_features_t features)
3911{
3912        struct sk_buff *segs = NULL;
3913        struct sk_buff *tail = NULL;
3914        struct sk_buff *list_skb = skb_shinfo(head_skb)->frag_list;
3915        skb_frag_t *frag = skb_shinfo(head_skb)->frags;
3916        unsigned int mss = skb_shinfo(head_skb)->gso_size;
3917        unsigned int doffset = head_skb->data - skb_mac_header(head_skb);
3918        struct sk_buff *frag_skb = head_skb;
3919        unsigned int offset = doffset;
3920        unsigned int tnl_hlen = skb_tnl_header_len(head_skb);
3921        unsigned int partial_segs = 0;
3922        unsigned int headroom;
3923        unsigned int len = head_skb->len;
3924        __be16 proto;
3925        bool csum, sg;
3926        int nfrags = skb_shinfo(head_skb)->nr_frags;
3927        int err = -ENOMEM;
3928        int i = 0;
3929        int pos;
3930
3931        if (list_skb && !list_skb->head_frag && skb_headlen(list_skb) &&
3932            (skb_shinfo(head_skb)->gso_type & SKB_GSO_DODGY)) {
3933                /* gso_size is untrusted, and we have a frag_list with a linear
3934                 * non head_frag head.
3935                 *
3936                 * (we assume checking the first list_skb member suffices;
3937                 * i.e if either of the list_skb members have non head_frag
3938                 * head, then the first one has too).
3939                 *
3940                 * If head_skb's headlen does not fit requested gso_size, it
3941                 * means that the frag_list members do NOT terminate on exact
3942                 * gso_size boundaries. Hence we cannot perform skb_frag_t page
3943                 * sharing. Therefore we must fallback to copying the frag_list
3944                 * skbs; we do so by disabling SG.
3945                 */
3946                if (mss != GSO_BY_FRAGS && mss != skb_headlen(head_skb))
3947                        features &= ~NETIF_F_SG;
3948        }
3949
3950        __skb_push(head_skb, doffset);
3951        proto = skb_network_protocol(head_skb, NULL);
3952        if (unlikely(!proto))
3953                return ERR_PTR(-EINVAL);
3954
3955        sg = !!(features & NETIF_F_SG);
3956        csum = !!can_checksum_protocol(features, proto);
3957
3958        if (sg && csum && (mss != GSO_BY_FRAGS))  {
3959                if (!(features & NETIF_F_GSO_PARTIAL)) {
3960                        struct sk_buff *iter;
3961                        unsigned int frag_len;
3962
3963                        if (!list_skb ||
3964                            !net_gso_ok(features, skb_shinfo(head_skb)->gso_type))
3965                                goto normal;
3966
3967                        /* If we get here then all the required
3968                         * GSO features except frag_list are supported.
3969                         * Try to split the SKB to multiple GSO SKBs
3970                         * with no frag_list.
3971                         * Currently we can do that only when the buffers don't
3972                         * have a linear part and all the buffers except
3973                         * the last are of the same length.
3974                         */
3975                        frag_len = list_skb->len;
3976                        skb_walk_frags(head_skb, iter) {
3977                                if (frag_len != iter->len && iter->next)
3978                                        goto normal;
3979                                if (skb_headlen(iter) && !iter->head_frag)
3980                                        goto normal;
3981
3982                                len -= iter->len;
3983                        }
3984
3985                        if (len != frag_len)
3986                                goto normal;
3987                }
3988
3989                /* GSO partial only requires that we trim off any excess that
3990                 * doesn't fit into an MSS sized block, so take care of that
3991                 * now.
3992                 */
3993                partial_segs = len / mss;
3994                if (partial_segs > 1)
3995                        mss *= partial_segs;
3996                else
3997                        partial_segs = 0;
3998        }
3999
4000normal:
4001        headroom = skb_headroom(head_skb);
4002        pos = skb_headlen(head_skb);
4003
4004        do {
4005                struct sk_buff *nskb;
4006                skb_frag_t *nskb_frag;
4007                int hsize;
4008                int size;
4009
4010                if (unlikely(mss == GSO_BY_FRAGS)) {
4011                        len = list_skb->len;
4012                } else {
4013                        len = head_skb->len - offset;
4014                        if (len > mss)
4015                                len = mss;
4016                }
4017
4018                hsize = skb_headlen(head_skb) - offset;
4019
4020                if (hsize <= 0 && i >= nfrags && skb_headlen(list_skb) &&
4021                    (skb_headlen(list_skb) == len || sg)) {
4022                        BUG_ON(skb_headlen(list_skb) > len);
4023
4024                        i = 0;
4025                        nfrags = skb_shinfo(list_skb)->nr_frags;
4026                        frag = skb_shinfo(list_skb)->frags;
4027                        frag_skb = list_skb;
4028                        pos += skb_headlen(list_skb);
4029
4030                        while (pos < offset + len) {
4031                                BUG_ON(i >= nfrags);
4032
4033                                size = skb_frag_size(frag);
4034                                if (pos + size > offset + len)
4035                                        break;
4036
4037                                i++;
4038                                pos += size;
4039                                frag++;
4040                        }
4041
4042                        nskb = skb_clone(list_skb, GFP_ATOMIC);
4043                        list_skb = list_skb->next;
4044
4045                        if (unlikely(!nskb))
4046                                goto err;
4047
4048                        if (unlikely(pskb_trim(nskb, len))) {
4049                                kfree_skb(nskb);
4050                                goto err;
4051                        }
4052
4053                        hsize = skb_end_offset(nskb);
4054                        if (skb_cow_head(nskb, doffset + headroom)) {
4055                                kfree_skb(nskb);
4056                                goto err;
4057                        }
4058
4059                        nskb->truesize += skb_end_offset(nskb) - hsize;
4060                        skb_release_head_state(nskb);
4061                        __skb_push(nskb, doffset);
4062                } else {
4063                        if (hsize < 0)
4064                                hsize = 0;
4065                        if (hsize > len || !sg)
4066                                hsize = len;
4067
4068                        nskb = __alloc_skb(hsize + doffset + headroom,
4069                                           GFP_ATOMIC, skb_alloc_rx_flag(head_skb),
4070                                           NUMA_NO_NODE);
4071
4072                        if (unlikely(!nskb))
4073                                goto err;
4074
4075                        skb_reserve(nskb, headroom);
4076                        __skb_put(nskb, doffset);
4077                }
4078
4079                if (segs)
4080                        tail->next = nskb;
4081                else
4082                        segs = nskb;
4083                tail = nskb;
4084
4085                __copy_skb_header(nskb, head_skb);
4086
4087                skb_headers_offset_update(nskb, skb_headroom(nskb) - headroom);
4088                skb_reset_mac_len(nskb);
4089
4090                skb_copy_from_linear_data_offset(head_skb, -tnl_hlen,
4091                                                 nskb->data - tnl_hlen,
4092                                                 doffset + tnl_hlen);
4093
4094                if (nskb->len == len + doffset)
4095                        goto perform_csum_check;
4096
4097                if (!sg) {
4098                        if (!csum) {
4099                                if (!nskb->remcsum_offload)
4100                                        nskb->ip_summed = CHECKSUM_NONE;
4101                                SKB_GSO_CB(nskb)->csum =
4102                                        skb_copy_and_csum_bits(head_skb, offset,
4103                                                               skb_put(nskb,
4104                                                                       len),
4105                                                               len);
4106                                SKB_GSO_CB(nskb)->csum_start =
4107                                        skb_headroom(nskb) + doffset;
4108                        } else {
4109                                skb_copy_bits(head_skb, offset,
4110                                              skb_put(nskb, len),
4111                                              len);
4112                        }
4113                        continue;
4114                }
4115
4116                nskb_frag = skb_shinfo(nskb)->frags;
4117
4118                skb_copy_from_linear_data_offset(head_skb, offset,
4119                                                 skb_put(nskb, hsize), hsize);
4120
4121                skb_shinfo(nskb)->flags |= skb_shinfo(head_skb)->flags &
4122                                           SKBFL_SHARED_FRAG;
4123
4124                if (skb_orphan_frags(frag_skb, GFP_ATOMIC) ||
4125                    skb_zerocopy_clone(nskb, frag_skb, GFP_ATOMIC))
4126                        goto err;
4127
4128                while (pos < offset + len) {
4129                        if (i >= nfrags) {
4130                                i = 0;
4131                                nfrags = skb_shinfo(list_skb)->nr_frags;
4132                                frag = skb_shinfo(list_skb)->frags;
4133                                frag_skb = list_skb;
4134                                if (!skb_headlen(list_skb)) {
4135                                        BUG_ON(!nfrags);
4136                                } else {
4137                                        BUG_ON(!list_skb->head_frag);
4138
4139                                        /* to make room for head_frag. */
4140                                        i--;
4141                                        frag--;
4142                                }
4143                                if (skb_orphan_frags(frag_skb, GFP_ATOMIC) ||
4144                                    skb_zerocopy_clone(nskb, frag_skb,
4145                                                       GFP_ATOMIC))
4146                                        goto err;
4147
4148                                list_skb = list_skb->next;
4149                        }
4150
4151                        if (unlikely(skb_shinfo(nskb)->nr_frags >=
4152                                     MAX_SKB_FRAGS)) {
4153                                net_warn_ratelimited(
4154                                        "skb_segment: too many frags: %u %u\n",
4155                                        pos, mss);
4156                                err = -EINVAL;
4157                                goto err;
4158                        }
4159
4160                        *nskb_frag = (i < 0) ? skb_head_frag_to_page_desc(frag_skb) : *frag;
4161                        __skb_frag_ref(nskb_frag);
4162                        size = skb_frag_size(nskb_frag);
4163
4164                        if (pos < offset) {
4165                                skb_frag_off_add(nskb_frag, offset - pos);
4166                                skb_frag_size_sub(nskb_frag, offset - pos);
4167                        }
4168
4169                        skb_shinfo(nskb)->nr_frags++;
4170
4171                        if (pos + size <= offset + len) {
4172                                i++;
4173                                frag++;
4174                                pos += size;
4175                        } else {
4176                                skb_frag_size_sub(nskb_frag, pos + size - (offset + len));
4177                                goto skip_fraglist;
4178                        }
4179
4180                        nskb_frag++;
4181                }
4182
4183skip_fraglist:
4184                nskb->data_len = len - hsize;
4185                nskb->len += nskb->data_len;
4186                nskb->truesize += nskb->data_len;
4187
4188perform_csum_check:
4189                if (!csum) {
4190                        if (skb_has_shared_frag(nskb) &&
4191                            __skb_linearize(nskb))
4192                                goto err;
4193
4194                        if (!nskb->remcsum_offload)
4195                                nskb->ip_summed = CHECKSUM_NONE;
4196                        SKB_GSO_CB(nskb)->csum =
4197                                skb_checksum(nskb, doffset,
4198                                             nskb->len - doffset, 0);
4199                        SKB_GSO_CB(nskb)->csum_start =
4200                                skb_headroom(nskb) + doffset;
4201                }
4202        } while ((offset += len) < head_skb->len);
4203
4204        /* Some callers want to get the end of the list.
4205         * Put it in segs->prev to avoid walking the list.
4206         * (see validate_xmit_skb_list() for example)
4207         */
4208        segs->prev = tail;
4209
4210        if (partial_segs) {
4211                struct sk_buff *iter;
4212                int type = skb_shinfo(head_skb)->gso_type;
4213                unsigned short gso_size = skb_shinfo(head_skb)->gso_size;
4214
4215                /* Update type to add partial and then remove dodgy if set */
4216                type |= (features & NETIF_F_GSO_PARTIAL) / NETIF_F_GSO_PARTIAL * SKB_GSO_PARTIAL;
4217                type &= ~SKB_GSO_DODGY;
4218
4219                /* Update GSO info and prepare to start updating headers on
4220                 * our way back down the stack of protocols.
4221                 */
4222                for (iter = segs; iter; iter = iter->next) {
4223                        skb_shinfo(iter)->gso_size = gso_size;
4224                        skb_shinfo(iter)->gso_segs = partial_segs;
4225                        skb_shinfo(iter)->gso_type = type;
4226                        SKB_GSO_CB(iter)->data_offset = skb_headroom(iter) + doffset;
4227                }
4228
4229                if (tail->len - doffset <= gso_size)
4230                        skb_shinfo(tail)->gso_size = 0;
4231                else if (tail != segs)
4232                        skb_shinfo(tail)->gso_segs = DIV_ROUND_UP(tail->len - doffset, gso_size);
4233        }
4234
4235        /* Following permits correct backpressure, for protocols
4236         * using skb_set_owner_w().
4237         * Idea is to tranfert ownership from head_skb to last segment.
4238         */
4239        if (head_skb->destructor == sock_wfree) {
4240                swap(tail->truesize, head_skb->truesize);
4241                swap(tail->destructor, head_skb->destructor);
4242                swap(tail->sk, head_skb->sk);
4243        }
4244        return segs;
4245
4246err:
4247        kfree_skb_list(segs);
4248        return ERR_PTR(err);
4249}
4250EXPORT_SYMBOL_GPL(skb_segment);
4251
4252int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
4253{
4254        struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb);
4255        unsigned int offset = skb_gro_offset(skb);
4256        unsigned int headlen = skb_headlen(skb);
4257        unsigned int len = skb_gro_len(skb);
4258        unsigned int delta_truesize;
4259        struct sk_buff *lp;
4260
4261        if (unlikely(p->len + len >= 65536 || NAPI_GRO_CB(skb)->flush))
4262                return -E2BIG;
4263
4264        lp = NAPI_GRO_CB(p)->last;
4265        pinfo = skb_shinfo(lp);
4266
4267        if (headlen <= offset) {
4268                skb_frag_t *frag;
4269                skb_frag_t *frag2;
4270                int i = skbinfo->nr_frags;
4271                int nr_frags = pinfo->nr_frags + i;
4272
4273                if (nr_frags > MAX_SKB_FRAGS)
4274                        goto merge;
4275
4276                offset -= headlen;
4277                pinfo->nr_frags = nr_frags;
4278                skbinfo->nr_frags = 0;
4279
4280                frag = pinfo->frags + nr_frags;
4281                frag2 = skbinfo->frags + i;
4282                do {
4283                        *--frag = *--frag2;
4284                } while (--i);
4285
4286                skb_frag_off_add(frag, offset);
4287                skb_frag_size_sub(frag, offset);
4288
4289                /* all fragments truesize : remove (head size + sk_buff) */
4290                delta_truesize = skb->truesize -
4291                                 SKB_TRUESIZE(skb_end_offset(skb));
4292
4293                skb->truesize -= skb->data_len;
4294                skb->len -= skb->data_len;
4295                skb->data_len = 0;
4296
4297                NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
4298                goto done;
4299        } else if (skb->head_frag) {
4300                int nr_frags = pinfo->nr_frags;
4301                skb_frag_t *frag = pinfo->frags + nr_frags;
4302                struct page *page = virt_to_head_page(skb->head);
4303                unsigned int first_size = headlen - offset;
4304                unsigned int first_offset;
4305
4306                if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
4307                        goto merge;
4308
4309                first_offset = skb->data -
4310                               (unsigned char *)page_address(page) +
4311                               offset;
4312
4313                pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;
4314
4315                __skb_frag_set_page(frag, page);
4316                skb_frag_off_set(frag, first_offset);
4317                skb_frag_size_set(frag, first_size);
4318
4319                memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
4320                /* We dont need to clear skbinfo->nr_frags here */
4321
4322                delta_truesize = skb->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
4323                NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
4324                goto done;
4325        }
4326
4327merge:
4328        delta_truesize = skb->truesize;
4329        if (offset > headlen) {
4330                unsigned int eat = offset - headlen;
4331
4332                skb_frag_off_add(&skbinfo->frags[0], eat);
4333                skb_frag_size_sub(&skbinfo->frags[0], eat);
4334                skb->data_len -= eat;
4335                skb->len -= eat;
4336                offset = headlen;
4337        }
4338
4339        __skb_pull(skb, offset);
4340
4341        if (NAPI_GRO_CB(p)->last == p)
4342                skb_shinfo(p)->frag_list = skb;
4343        else
4344                NAPI_GRO_CB(p)->last->next = skb;
4345        NAPI_GRO_CB(p)->last = skb;
4346        __skb_header_release(skb);
4347        lp = p;
4348
4349done:
4350        NAPI_GRO_CB(p)->count++;
4351        p->data_len += len;
4352        p->truesize += delta_truesize;
4353        p->len += len;
4354        if (lp != p) {
4355                lp->data_len += len;
4356                lp->truesize += delta_truesize;
4357                lp->len += len;
4358        }
4359        NAPI_GRO_CB(skb)->same_flow = 1;
4360        return 0;
4361}
4362
4363#ifdef CONFIG_SKB_EXTENSIONS
4364#define SKB_EXT_ALIGN_VALUE     8
4365#define SKB_EXT_CHUNKSIZEOF(x)  (ALIGN((sizeof(x)), SKB_EXT_ALIGN_VALUE) / SKB_EXT_ALIGN_VALUE)
4366
4367static const u8 skb_ext_type_len[] = {
4368#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
4369        [SKB_EXT_BRIDGE_NF] = SKB_EXT_CHUNKSIZEOF(struct nf_bridge_info),
4370#endif
4371#ifdef CONFIG_XFRM
4372        [SKB_EXT_SEC_PATH] = SKB_EXT_CHUNKSIZEOF(struct sec_path),
4373#endif
4374#if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
4375        [TC_SKB_EXT] = SKB_EXT_CHUNKSIZEOF(struct tc_skb_ext),
4376#endif
4377#if IS_ENABLED(CONFIG_MPTCP)
4378        [SKB_EXT_MPTCP] = SKB_EXT_CHUNKSIZEOF(struct mptcp_ext),
4379#endif
4380};
4381
4382static __always_inline unsigned int skb_ext_total_length(void)
4383{
4384        return SKB_EXT_CHUNKSIZEOF(struct skb_ext) +
4385#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
4386                skb_ext_type_len[SKB_EXT_BRIDGE_NF] +
4387#endif
4388#ifdef CONFIG_XFRM
4389                skb_ext_type_len[SKB_EXT_SEC_PATH] +
4390#endif
4391#if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
4392                skb_ext_type_len[TC_SKB_EXT] +
4393#endif
4394#if IS_ENABLED(CONFIG_MPTCP)
4395                skb_ext_type_len[SKB_EXT_MPTCP] +
4396#endif
4397                0;
4398}
4399
4400static void skb_extensions_init(void)
4401{
4402        BUILD_BUG_ON(SKB_EXT_NUM >= 8);
4403        BUILD_BUG_ON(skb_ext_total_length() > 255);
4404
4405        skbuff_ext_cache = kmem_cache_create("skbuff_ext_cache",
4406                                             SKB_EXT_ALIGN_VALUE * skb_ext_total_length(),
4407                                             0,
4408                                             SLAB_HWCACHE_ALIGN|SLAB_PANIC,
4409                                             NULL);
4410}
4411#else
4412static void skb_extensions_init(void) {}
4413#endif
4414
4415void __init skb_init(void)
4416{
4417        skbuff_head_cache = kmem_cache_create_usercopy("skbuff_head_cache",
4418                                              sizeof(struct sk_buff),
4419                                              0,
4420                                              SLAB_HWCACHE_ALIGN|SLAB_PANIC,
4421                                              offsetof(struct sk_buff, cb),
4422                                              sizeof_field(struct sk_buff, cb),
4423                                              NULL);
4424        skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
4425                                                sizeof(struct sk_buff_fclones),
4426                                                0,
4427                                                SLAB_HWCACHE_ALIGN|SLAB_PANIC,
4428                                                NULL);
4429        skb_extensions_init();
4430}
4431
4432static int
4433__skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len,
4434               unsigned int recursion_level)
4435{
4436        int start = skb_headlen(skb);
4437        int i, copy = start - offset;
4438        struct sk_buff *frag_iter;
4439        int elt = 0;
4440
4441        if (unlikely(recursion_level >= 24))
4442                return -EMSGSIZE;
4443
4444        if (copy > 0) {
4445                if (copy > len)
4446                        copy = len;
4447                sg_set_buf(sg, skb->data + offset, copy);
4448                elt++;
4449                if ((len -= copy) == 0)
4450                        return elt;
4451                offset += copy;
4452        }
4453
4454        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
4455                int end;
4456
4457                WARN_ON(start > offset + len);
4458
4459                end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
4460                if ((copy = end - offset) > 0) {
4461                        skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
4462                        if (unlikely(elt && sg_is_last(&sg[elt - 1])))
4463                                return -EMSGSIZE;
4464
4465                        if (copy > len)
4466                                copy = len;
4467                        sg_set_page(&sg[elt], skb_frag_page(frag), copy,
4468                                    skb_frag_off(frag) + offset - start);
4469                        elt++;
4470                        if (!(len -= copy))
4471                                return elt;
4472                        offset += copy;
4473                }
4474                start = end;
4475        }
4476
4477        skb_walk_frags(skb, frag_iter) {
4478                int end, ret;
4479
4480                WARN_ON(start > offset + len);
4481
4482                end = start + frag_iter->len;
4483                if ((copy = end - offset) > 0) {
4484                        if (unlikely(elt && sg_is_last(&sg[elt - 1])))
4485                                return -EMSGSIZE;
4486
4487                        if (copy > len)
4488                                copy = len;
4489                        ret = __skb_to_sgvec(frag_iter, sg+elt, offset - start,
4490                                              copy, recursion_level + 1);
4491                        if (unlikely(ret < 0))
4492                                return ret;
4493                        elt += ret;
4494                        if ((len -= copy) == 0)
4495                                return elt;
4496                        offset += copy;
4497                }
4498                start = end;
4499        }
4500        BUG_ON(len);
4501        return elt;
4502}
4503
4504/**
4505 *      skb_to_sgvec - Fill a scatter-gather list from a socket buffer
4506 *      @skb: Socket buffer containing the buffers to be mapped
4507 *      @sg: The scatter-gather list to map into
4508 *      @offset: The offset into the buffer's contents to start mapping
4509 *      @len: Length of buffer space to be mapped
4510 *
4511 *      Fill the specified scatter-gather list with mappings/pointers into a
4512 *      region of the buffer space attached to a socket buffer. Returns either
4513 *      the number of scatterlist items used, or -EMSGSIZE if the contents
4514 *      could not fit.
4515 */
4516int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
4517{
4518        int nsg = __skb_to_sgvec(skb, sg, offset, len, 0);
4519
4520        if (nsg <= 0)
4521                return nsg;
4522
4523        sg_mark_end(&sg[nsg - 1]);
4524
4525        return nsg;
4526}
4527EXPORT_SYMBOL_GPL(skb_to_sgvec);
4528
4529/* As compared with skb_to_sgvec, skb_to_sgvec_nomark only map skb to given
4530 * sglist without mark the sg which contain last skb data as the end.
4531 * So the caller can mannipulate sg list as will when padding new data after
4532 * the first call without calling sg_unmark_end to expend sg list.
4533 *
4534 * Scenario to use skb_to_sgvec_nomark:
4535 * 1. sg_init_table
4536 * 2. skb_to_sgvec_nomark(payload1)
4537 * 3. skb_to_sgvec_nomark(payload2)
4538 *
4539 * This is equivalent to:
4540 * 1. sg_init_table
4541 * 2. skb_to_sgvec(payload1)
4542 * 3. sg_unmark_end
4543 * 4. skb_to_sgvec(payload2)
4544 *
4545 * When mapping mutilple payload conditionally, skb_to_sgvec_nomark
4546 * is more preferable.
4547 */
4548int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
4549                        int offset, int len)
4550{
4551        return __skb_to_sgvec(skb, sg, offset, len, 0);
4552}
4553EXPORT_SYMBOL_GPL(skb_to_sgvec_nomark);
4554
4555
4556
4557/**
4558 *      skb_cow_data - Check that a socket buffer's data buffers are writable
4559 *      @skb: The socket buffer to check.
4560 *      @tailbits: Amount of trailing space to be added
4561 *      @trailer: Returned pointer to the skb where the @tailbits space begins
4562 *
4563 *      Make sure that the data buffers attached to a socket buffer are
4564 *      writable. If they are not, private copies are made of the data buffers
4565 *      and the socket buffer is set to use these instead.
4566 *
4567 *      If @tailbits is given, make sure that there is space to write @tailbits
4568 *      bytes of data beyond current end of socket buffer.  @trailer will be
4569 *      set to point to the skb in which this space begins.
4570 *
4571 *      The number of scatterlist elements required to completely map the
4572 *      COW'd and extended socket buffer will be returned.
4573 */
4574int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
4575{
4576        int copyflag;
4577        int elt;
4578        struct sk_buff *skb1, **skb_p;
4579
4580        /* If skb is cloned or its head is paged, reallocate
4581         * head pulling out all the pages (pages are considered not writable
4582         * at the moment even if they are anonymous).
4583         */
4584        if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
4585            !__pskb_pull_tail(skb, __skb_pagelen(skb)))
4586                return -ENOMEM;
4587
4588        /* Easy case. Most of packets will go this way. */
4589        if (!skb_has_frag_list(skb)) {
4590                /* A little of trouble, not enough of space for trailer.
4591                 * This should not happen, when stack is tuned to generate
4592                 * good frames. OK, on miss we reallocate and reserve even more
4593                 * space, 128 bytes is fair. */
4594
4595                if (skb_tailroom(skb) < tailbits &&
4596                    pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
4597                        return -ENOMEM;
4598
4599                /* Voila! */
4600                *trailer = skb;
4601                return 1;
4602        }
4603
4604        /* Misery. We are in troubles, going to mincer fragments... */
4605
4606        elt = 1;
4607        skb_p = &skb_shinfo(skb)->frag_list;
4608        copyflag = 0;
4609
4610        while ((skb1 = *skb_p) != NULL) {
4611                int ntail = 0;
4612
4613                /* The fragment is partially pulled by someone,
4614                 * this can happen on input. Copy it and everything
4615                 * after it. */
4616
4617                if (skb_shared(skb1))
4618                        copyflag = 1;
4619
4620                /* If the skb is the last, worry about trailer. */
4621
4622                if (skb1->next == NULL && tailbits) {
4623                        if (skb_shinfo(skb1)->nr_frags ||
4624                            skb_has_frag_list(skb1) ||
4625                            skb_tailroom(skb1) < tailbits)
4626                                ntail = tailbits + 128;
4627                }
4628
4629                if (copyflag ||
4630                    skb_cloned(skb1) ||
4631                    ntail ||
4632                    skb_shinfo(skb1)->nr_frags ||
4633                    skb_has_frag_list(skb1)) {
4634                        struct sk_buff *skb2;
4635
4636                        /* Fuck, we are miserable poor guys... */
4637                        if (ntail == 0)
4638                                skb2 = skb_copy(skb1, GFP_ATOMIC);
4639                        else
4640                                skb2 = skb_copy_expand(skb1,
4641                                                       skb_headroom(skb1),
4642                                                       ntail,
4643                                                       GFP_ATOMIC);
4644                        if (unlikely(skb2 == NULL))
4645                                return -ENOMEM;
4646
4647                        if (skb1->sk)
4648                                skb_set_owner_w(skb2, skb1->sk);
4649
4650                        /* Looking around. Are we still alive?
4651                         * OK, link new skb, drop old one */
4652
4653                        skb2->next = skb1->next;
4654                        *skb_p = skb2;
4655                        kfree_skb(skb1);
4656                        skb1 = skb2;
4657                }
4658                elt++;
4659                *trailer = skb1;
4660                skb_p = &skb1->next;
4661        }
4662
4663        return elt;
4664}
4665EXPORT_SYMBOL_GPL(skb_cow_data);
4666
4667static void sock_rmem_free(struct sk_buff *skb)
4668{
4669        struct sock *sk = skb->sk;
4670
4671        atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
4672}
4673
4674static void skb_set_err_queue(struct sk_buff *skb)
4675{
4676        /* pkt_type of skbs received on local sockets is never PACKET_OUTGOING.
4677         * So, it is safe to (mis)use it to mark skbs on the error queue.
4678         */
4679        skb->pkt_type = PACKET_OUTGOING;
4680        BUILD_BUG_ON(PACKET_OUTGOING == 0);
4681}
4682
4683/*
4684 * Note: We dont mem charge error packets (no sk_forward_alloc changes)
4685 */
4686int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
4687{
4688        if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
4689            (unsigned int)READ_ONCE(sk->sk_rcvbuf))
4690                return -ENOMEM;
4691
4692        skb_orphan(skb);
4693        skb->sk = sk;
4694        skb->destructor = sock_rmem_free;
4695        atomic_add(skb->truesize, &sk->sk_rmem_alloc);
4696        skb_set_err_queue(skb);
4697
4698        /* before exiting rcu section, make sure dst is refcounted */
4699        skb_dst_force(skb);
4700
4701        skb_queue_tail(&sk->sk_error_queue, skb);
4702        if (!sock_flag(sk, SOCK_DEAD))
4703                sk_error_report(sk);
4704        return 0;
4705}
4706EXPORT_SYMBOL(sock_queue_err_skb);