linux/net/mptcp/protocol.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/* Multipath TCP
   3 *
   4 * Copyright (c) 2017 - 2019, Intel Corporation.
   5 */
   6
   7#define pr_fmt(fmt) "MPTCP: " fmt
   8
   9#include <linux/kernel.h>
  10#include <linux/module.h>
  11#include <linux/netdevice.h>
  12#include <linux/sched/signal.h>
  13#include <linux/atomic.h>
  14#include <net/sock.h>
  15#include <net/inet_common.h>
  16#include <net/inet_hashtables.h>
  17#include <net/protocol.h>
  18#include <net/tcp.h>
  19#include <net/tcp_states.h>
  20#if IS_ENABLED(CONFIG_MPTCP_IPV6)
  21#include <net/transp_v6.h>
  22#endif
  23#include <net/mptcp.h>
  24#include <net/xfrm.h>
  25#include "protocol.h"
  26#include "mib.h"
  27
  28#define CREATE_TRACE_POINTS
  29#include <trace/events/mptcp.h>
  30
  31#if IS_ENABLED(CONFIG_MPTCP_IPV6)
  32struct mptcp6_sock {
  33        struct mptcp_sock msk;
  34        struct ipv6_pinfo np;
  35};
  36#endif
  37
  38struct mptcp_skb_cb {
  39        u64 map_seq;
  40        u64 end_seq;
  41        u32 offset;
  42        u8  has_rxtstamp:1;
  43};
  44
  45#define MPTCP_SKB_CB(__skb)     ((struct mptcp_skb_cb *)&((__skb)->cb[0]))
  46
  47enum {
  48        MPTCP_CMSG_TS = BIT(0),
  49};
  50
  51static struct percpu_counter mptcp_sockets_allocated;
  52
  53static void __mptcp_destroy_sock(struct sock *sk);
  54static void __mptcp_check_send_data_fin(struct sock *sk);
  55
  56DEFINE_PER_CPU(struct mptcp_delegated_action, mptcp_delegated_actions);
  57static struct net_device mptcp_napi_dev;
  58
  59/* If msk has an initial subflow socket, and the MP_CAPABLE handshake has not
  60 * completed yet or has failed, return the subflow socket.
  61 * Otherwise return NULL.
  62 */
  63struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk)
  64{
  65        if (!msk->subflow || READ_ONCE(msk->can_ack))
  66                return NULL;
  67
  68        return msk->subflow;
  69}
  70
  71/* Returns end sequence number of the receiver's advertised window */
  72static u64 mptcp_wnd_end(const struct mptcp_sock *msk)
  73{
  74        return READ_ONCE(msk->wnd_end);
  75}
  76
  77static bool mptcp_is_tcpsk(struct sock *sk)
  78{
  79        struct socket *sock = sk->sk_socket;
  80
  81        if (unlikely(sk->sk_prot == &tcp_prot)) {
  82                /* we are being invoked after mptcp_accept() has
  83                 * accepted a non-mp-capable flow: sk is a tcp_sk,
  84                 * not an mptcp one.
  85                 *
  86                 * Hand the socket over to tcp so all further socket ops
  87                 * bypass mptcp.
  88                 */
  89                sock->ops = &inet_stream_ops;
  90                return true;
  91#if IS_ENABLED(CONFIG_MPTCP_IPV6)
  92        } else if (unlikely(sk->sk_prot == &tcpv6_prot)) {
  93                sock->ops = &inet6_stream_ops;
  94                return true;
  95#endif
  96        }
  97
  98        return false;
  99}
 100
 101static int __mptcp_socket_create(struct mptcp_sock *msk)
 102{
 103        struct mptcp_subflow_context *subflow;
 104        struct sock *sk = (struct sock *)msk;
 105        struct socket *ssock;
 106        int err;
 107
 108        err = mptcp_subflow_create_socket(sk, &ssock);
 109        if (err)
 110                return err;
 111
 112        msk->first = ssock->sk;
 113        msk->subflow = ssock;
 114        subflow = mptcp_subflow_ctx(ssock->sk);
 115        list_add(&subflow->node, &msk->conn_list);
 116        sock_hold(ssock->sk);
 117        subflow->request_mptcp = 1;
 118        mptcp_sock_graft(msk->first, sk->sk_socket);
 119
 120        return 0;
 121}
 122
 123static void mptcp_drop(struct sock *sk, struct sk_buff *skb)
 124{
 125        sk_drops_add(sk, skb);
 126        __kfree_skb(skb);
 127}
 128
 129static bool mptcp_try_coalesce(struct sock *sk, struct sk_buff *to,
 130                               struct sk_buff *from)
 131{
 132        bool fragstolen;
 133        int delta;
 134
 135        if (MPTCP_SKB_CB(from)->offset ||
 136            !skb_try_coalesce(to, from, &fragstolen, &delta))
 137                return false;
 138
 139        pr_debug("colesced seq %llx into %llx new len %d new end seq %llx",
 140                 MPTCP_SKB_CB(from)->map_seq, MPTCP_SKB_CB(to)->map_seq,
 141                 to->len, MPTCP_SKB_CB(from)->end_seq);
 142        MPTCP_SKB_CB(to)->end_seq = MPTCP_SKB_CB(from)->end_seq;
 143        kfree_skb_partial(from, fragstolen);
 144        atomic_add(delta, &sk->sk_rmem_alloc);
 145        sk_mem_charge(sk, delta);
 146        return true;
 147}
 148
 149static bool mptcp_ooo_try_coalesce(struct mptcp_sock *msk, struct sk_buff *to,
 150                                   struct sk_buff *from)
 151{
 152        if (MPTCP_SKB_CB(from)->map_seq != MPTCP_SKB_CB(to)->end_seq)
 153                return false;
 154
 155        return mptcp_try_coalesce((struct sock *)msk, to, from);
 156}
 157
 158/* "inspired" by tcp_data_queue_ofo(), main differences:
 159 * - use mptcp seqs
 160 * - don't cope with sacks
 161 */
 162static void mptcp_data_queue_ofo(struct mptcp_sock *msk, struct sk_buff *skb)
 163{
 164        struct sock *sk = (struct sock *)msk;
 165        struct rb_node **p, *parent;
 166        u64 seq, end_seq, max_seq;
 167        struct sk_buff *skb1;
 168
 169        seq = MPTCP_SKB_CB(skb)->map_seq;
 170        end_seq = MPTCP_SKB_CB(skb)->end_seq;
 171        max_seq = READ_ONCE(msk->rcv_wnd_sent);
 172
 173        pr_debug("msk=%p seq=%llx limit=%llx empty=%d", msk, seq, max_seq,
 174                 RB_EMPTY_ROOT(&msk->out_of_order_queue));
 175        if (after64(end_seq, max_seq)) {
 176                /* out of window */
 177                mptcp_drop(sk, skb);
 178                pr_debug("oow by %lld, rcv_wnd_sent %llu\n",
 179                         (unsigned long long)end_seq - (unsigned long)max_seq,
 180                         (unsigned long long)msk->rcv_wnd_sent);
 181                MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_NODSSWINDOW);
 182                return;
 183        }
 184
 185        p = &msk->out_of_order_queue.rb_node;
 186        MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOQUEUE);
 187        if (RB_EMPTY_ROOT(&msk->out_of_order_queue)) {
 188                rb_link_node(&skb->rbnode, NULL, p);
 189                rb_insert_color(&skb->rbnode, &msk->out_of_order_queue);
 190                msk->ooo_last_skb = skb;
 191                goto end;
 192        }
 193
 194        /* with 2 subflows, adding at end of ooo queue is quite likely
 195         * Use of ooo_last_skb avoids the O(Log(N)) rbtree lookup.
 196         */
 197        if (mptcp_ooo_try_coalesce(msk, msk->ooo_last_skb, skb)) {
 198                MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOMERGE);
 199                MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOQUEUETAIL);
 200                return;
 201        }
 202
 203        /* Can avoid an rbtree lookup if we are adding skb after ooo_last_skb */
 204        if (!before64(seq, MPTCP_SKB_CB(msk->ooo_last_skb)->end_seq)) {
 205                MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOQUEUETAIL);
 206                parent = &msk->ooo_last_skb->rbnode;
 207                p = &parent->rb_right;
 208                goto insert;
 209        }
 210
 211        /* Find place to insert this segment. Handle overlaps on the way. */
 212        parent = NULL;
 213        while (*p) {
 214                parent = *p;
 215                skb1 = rb_to_skb(parent);
 216                if (before64(seq, MPTCP_SKB_CB(skb1)->map_seq)) {
 217                        p = &parent->rb_left;
 218                        continue;
 219                }
 220                if (before64(seq, MPTCP_SKB_CB(skb1)->end_seq)) {
 221                        if (!after64(end_seq, MPTCP_SKB_CB(skb1)->end_seq)) {
 222                                /* All the bits are present. Drop. */
 223                                mptcp_drop(sk, skb);
 224                                MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
 225                                return;
 226                        }
 227                        if (after64(seq, MPTCP_SKB_CB(skb1)->map_seq)) {
 228                                /* partial overlap:
 229                                 *     |     skb      |
 230                                 *  |     skb1    |
 231                                 * continue traversing
 232                                 */
 233                        } else {
 234                                /* skb's seq == skb1's seq and skb covers skb1.
 235                                 * Replace skb1 with skb.
 236                                 */
 237                                rb_replace_node(&skb1->rbnode, &skb->rbnode,
 238                                                &msk->out_of_order_queue);
 239                                mptcp_drop(sk, skb1);
 240                                MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
 241                                goto merge_right;
 242                        }
 243                } else if (mptcp_ooo_try_coalesce(msk, skb1, skb)) {
 244                        MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOMERGE);
 245                        return;
 246                }
 247                p = &parent->rb_right;
 248        }
 249
 250insert:
 251        /* Insert segment into RB tree. */
 252        rb_link_node(&skb->rbnode, parent, p);
 253        rb_insert_color(&skb->rbnode, &msk->out_of_order_queue);
 254
 255merge_right:
 256        /* Remove other segments covered by skb. */
 257        while ((skb1 = skb_rb_next(skb)) != NULL) {
 258                if (before64(end_seq, MPTCP_SKB_CB(skb1)->end_seq))
 259                        break;
 260                rb_erase(&skb1->rbnode, &msk->out_of_order_queue);
 261                mptcp_drop(sk, skb1);
 262                MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
 263        }
 264        /* If there is no skb after us, we are the last_skb ! */
 265        if (!skb1)
 266                msk->ooo_last_skb = skb;
 267
 268end:
 269        skb_condense(skb);
 270        skb_set_owner_r(skb, sk);
 271}
 272
 273static bool __mptcp_move_skb(struct mptcp_sock *msk, struct sock *ssk,
 274                             struct sk_buff *skb, unsigned int offset,
 275                             size_t copy_len)
 276{
 277        struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 278        struct sock *sk = (struct sock *)msk;
 279        struct sk_buff *tail;
 280        bool has_rxtstamp;
 281
 282        __skb_unlink(skb, &ssk->sk_receive_queue);
 283
 284        skb_ext_reset(skb);
 285        skb_orphan(skb);
 286
 287        /* try to fetch required memory from subflow */
 288        if (!sk_rmem_schedule(sk, skb, skb->truesize)) {
 289                int amount = sk_mem_pages(skb->truesize) << SK_MEM_QUANTUM_SHIFT;
 290
 291                if (ssk->sk_forward_alloc < amount)
 292                        goto drop;
 293
 294                ssk->sk_forward_alloc -= amount;
 295                sk->sk_forward_alloc += amount;
 296        }
 297
 298        has_rxtstamp = TCP_SKB_CB(skb)->has_rxtstamp;
 299
 300        /* the skb map_seq accounts for the skb offset:
 301         * mptcp_subflow_get_mapped_dsn() is based on the current tp->copied_seq
 302         * value
 303         */
 304        MPTCP_SKB_CB(skb)->map_seq = mptcp_subflow_get_mapped_dsn(subflow);
 305        MPTCP_SKB_CB(skb)->end_seq = MPTCP_SKB_CB(skb)->map_seq + copy_len;
 306        MPTCP_SKB_CB(skb)->offset = offset;
 307        MPTCP_SKB_CB(skb)->has_rxtstamp = has_rxtstamp;
 308
 309        if (MPTCP_SKB_CB(skb)->map_seq == msk->ack_seq) {
 310                /* in sequence */
 311                WRITE_ONCE(msk->ack_seq, msk->ack_seq + copy_len);
 312                tail = skb_peek_tail(&sk->sk_receive_queue);
 313                if (tail && mptcp_try_coalesce(sk, tail, skb))
 314                        return true;
 315
 316                skb_set_owner_r(skb, sk);
 317                __skb_queue_tail(&sk->sk_receive_queue, skb);
 318                return true;
 319        } else if (after64(MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq)) {
 320                mptcp_data_queue_ofo(msk, skb);
 321                return false;
 322        }
 323
 324        /* old data, keep it simple and drop the whole pkt, sender
 325         * will retransmit as needed, if needed.
 326         */
 327        MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
 328drop:
 329        mptcp_drop(sk, skb);
 330        return false;
 331}
 332
 333static void mptcp_stop_timer(struct sock *sk)
 334{
 335        struct inet_connection_sock *icsk = inet_csk(sk);
 336
 337        sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
 338        mptcp_sk(sk)->timer_ival = 0;
 339}
 340
 341static void mptcp_close_wake_up(struct sock *sk)
 342{
 343        if (sock_flag(sk, SOCK_DEAD))
 344                return;
 345
 346        sk->sk_state_change(sk);
 347        if (sk->sk_shutdown == SHUTDOWN_MASK ||
 348            sk->sk_state == TCP_CLOSE)
 349                sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
 350        else
 351                sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
 352}
 353
 354static bool mptcp_pending_data_fin_ack(struct sock *sk)
 355{
 356        struct mptcp_sock *msk = mptcp_sk(sk);
 357
 358        return !__mptcp_check_fallback(msk) &&
 359               ((1 << sk->sk_state) &
 360                (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK)) &&
 361               msk->write_seq == READ_ONCE(msk->snd_una);
 362}
 363
 364static void mptcp_check_data_fin_ack(struct sock *sk)
 365{
 366        struct mptcp_sock *msk = mptcp_sk(sk);
 367
 368        /* Look for an acknowledged DATA_FIN */
 369        if (mptcp_pending_data_fin_ack(sk)) {
 370                WRITE_ONCE(msk->snd_data_fin_enable, 0);
 371
 372                switch (sk->sk_state) {
 373                case TCP_FIN_WAIT1:
 374                        inet_sk_state_store(sk, TCP_FIN_WAIT2);
 375                        break;
 376                case TCP_CLOSING:
 377                case TCP_LAST_ACK:
 378                        inet_sk_state_store(sk, TCP_CLOSE);
 379                        break;
 380                }
 381
 382                mptcp_close_wake_up(sk);
 383        }
 384}
 385
 386static bool mptcp_pending_data_fin(struct sock *sk, u64 *seq)
 387{
 388        struct mptcp_sock *msk = mptcp_sk(sk);
 389
 390        if (READ_ONCE(msk->rcv_data_fin) &&
 391            ((1 << sk->sk_state) &
 392             (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_FIN_WAIT2))) {
 393                u64 rcv_data_fin_seq = READ_ONCE(msk->rcv_data_fin_seq);
 394
 395                if (msk->ack_seq == rcv_data_fin_seq) {
 396                        if (seq)
 397                                *seq = rcv_data_fin_seq;
 398
 399                        return true;
 400                }
 401        }
 402
 403        return false;
 404}
 405
 406static void mptcp_set_datafin_timeout(const struct sock *sk)
 407{
 408        struct inet_connection_sock *icsk = inet_csk(sk);
 409
 410        mptcp_sk(sk)->timer_ival = min(TCP_RTO_MAX,
 411                                       TCP_RTO_MIN << icsk->icsk_retransmits);
 412}
 413
 414static void mptcp_set_timeout(const struct sock *sk, const struct sock *ssk)
 415{
 416        long tout = ssk && inet_csk(ssk)->icsk_pending ?
 417                                      inet_csk(ssk)->icsk_timeout - jiffies : 0;
 418
 419        if (tout <= 0)
 420                tout = mptcp_sk(sk)->timer_ival;
 421        mptcp_sk(sk)->timer_ival = tout > 0 ? tout : TCP_RTO_MIN;
 422}
 423
 424static bool tcp_can_send_ack(const struct sock *ssk)
 425{
 426        return !((1 << inet_sk_state_load(ssk)) &
 427               (TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_TIME_WAIT | TCPF_CLOSE | TCPF_LISTEN));
 428}
 429
 430static void mptcp_send_ack(struct mptcp_sock *msk)
 431{
 432        struct mptcp_subflow_context *subflow;
 433
 434        mptcp_for_each_subflow(msk, subflow) {
 435                struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
 436                bool slow;
 437
 438                slow = lock_sock_fast(ssk);
 439                if (tcp_can_send_ack(ssk))
 440                        tcp_send_ack(ssk);
 441                unlock_sock_fast(ssk, slow);
 442        }
 443}
 444
 445static void mptcp_subflow_cleanup_rbuf(struct sock *ssk)
 446{
 447        bool slow;
 448
 449        slow = lock_sock_fast(ssk);
 450        if (tcp_can_send_ack(ssk))
 451                tcp_cleanup_rbuf(ssk, 1);
 452        unlock_sock_fast(ssk, slow);
 453}
 454
 455static bool mptcp_subflow_could_cleanup(const struct sock *ssk, bool rx_empty)
 456{
 457        const struct inet_connection_sock *icsk = inet_csk(ssk);
 458        u8 ack_pending = READ_ONCE(icsk->icsk_ack.pending);
 459        const struct tcp_sock *tp = tcp_sk(ssk);
 460
 461        return (ack_pending & ICSK_ACK_SCHED) &&
 462                ((READ_ONCE(tp->rcv_nxt) - READ_ONCE(tp->rcv_wup) >
 463                  READ_ONCE(icsk->icsk_ack.rcv_mss)) ||
 464                 (rx_empty && ack_pending &
 465                              (ICSK_ACK_PUSHED2 | ICSK_ACK_PUSHED)));
 466}
 467
 468static void mptcp_cleanup_rbuf(struct mptcp_sock *msk)
 469{
 470        int old_space = READ_ONCE(msk->old_wspace);
 471        struct mptcp_subflow_context *subflow;
 472        struct sock *sk = (struct sock *)msk;
 473        int space =  __mptcp_space(sk);
 474        bool cleanup, rx_empty;
 475
 476        cleanup = (space > 0) && (space >= (old_space << 1));
 477        rx_empty = !__mptcp_rmem(sk);
 478
 479        mptcp_for_each_subflow(msk, subflow) {
 480                struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
 481
 482                if (cleanup || mptcp_subflow_could_cleanup(ssk, rx_empty))
 483                        mptcp_subflow_cleanup_rbuf(ssk);
 484        }
 485}
 486
 487static bool mptcp_check_data_fin(struct sock *sk)
 488{
 489        struct mptcp_sock *msk = mptcp_sk(sk);
 490        u64 rcv_data_fin_seq;
 491        bool ret = false;
 492
 493        if (__mptcp_check_fallback(msk))
 494                return ret;
 495
 496        /* Need to ack a DATA_FIN received from a peer while this side
 497         * of the connection is in ESTABLISHED, FIN_WAIT1, or FIN_WAIT2.
 498         * msk->rcv_data_fin was set when parsing the incoming options
 499         * at the subflow level and the msk lock was not held, so this
 500         * is the first opportunity to act on the DATA_FIN and change
 501         * the msk state.
 502         *
 503         * If we are caught up to the sequence number of the incoming
 504         * DATA_FIN, send the DATA_ACK now and do state transition.  If
 505         * not caught up, do nothing and let the recv code send DATA_ACK
 506         * when catching up.
 507         */
 508
 509        if (mptcp_pending_data_fin(sk, &rcv_data_fin_seq)) {
 510                WRITE_ONCE(msk->ack_seq, msk->ack_seq + 1);
 511                WRITE_ONCE(msk->rcv_data_fin, 0);
 512
 513                sk->sk_shutdown |= RCV_SHUTDOWN;
 514                smp_mb__before_atomic(); /* SHUTDOWN must be visible first */
 515                set_bit(MPTCP_DATA_READY, &msk->flags);
 516
 517                switch (sk->sk_state) {
 518                case TCP_ESTABLISHED:
 519                        inet_sk_state_store(sk, TCP_CLOSE_WAIT);
 520                        break;
 521                case TCP_FIN_WAIT1:
 522                        inet_sk_state_store(sk, TCP_CLOSING);
 523                        break;
 524                case TCP_FIN_WAIT2:
 525                        inet_sk_state_store(sk, TCP_CLOSE);
 526                        break;
 527                default:
 528                        /* Other states not expected */
 529                        WARN_ON_ONCE(1);
 530                        break;
 531                }
 532
 533                ret = true;
 534                mptcp_set_timeout(sk, NULL);
 535                mptcp_send_ack(msk);
 536                mptcp_close_wake_up(sk);
 537        }
 538        return ret;
 539}
 540
 541static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
 542                                           struct sock *ssk,
 543                                           unsigned int *bytes)
 544{
 545        struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 546        struct sock *sk = (struct sock *)msk;
 547        unsigned int moved = 0;
 548        bool more_data_avail;
 549        struct tcp_sock *tp;
 550        bool done = false;
 551        int sk_rbuf;
 552
 553        sk_rbuf = READ_ONCE(sk->sk_rcvbuf);
 554
 555        if (!(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
 556                int ssk_rbuf = READ_ONCE(ssk->sk_rcvbuf);
 557
 558                if (unlikely(ssk_rbuf > sk_rbuf)) {
 559                        WRITE_ONCE(sk->sk_rcvbuf, ssk_rbuf);
 560                        sk_rbuf = ssk_rbuf;
 561                }
 562        }
 563
 564        pr_debug("msk=%p ssk=%p", msk, ssk);
 565        tp = tcp_sk(ssk);
 566        do {
 567                u32 map_remaining, offset;
 568                u32 seq = tp->copied_seq;
 569                struct sk_buff *skb;
 570                bool fin;
 571
 572                /* try to move as much data as available */
 573                map_remaining = subflow->map_data_len -
 574                                mptcp_subflow_get_map_offset(subflow);
 575
 576                skb = skb_peek(&ssk->sk_receive_queue);
 577                if (!skb) {
 578                        /* if no data is found, a racing workqueue/recvmsg
 579                         * already processed the new data, stop here or we
 580                         * can enter an infinite loop
 581                         */
 582                        if (!moved)
 583                                done = true;
 584                        break;
 585                }
 586
 587                if (__mptcp_check_fallback(msk)) {
 588                        /* if we are running under the workqueue, TCP could have
 589                         * collapsed skbs between dummy map creation and now
 590                         * be sure to adjust the size
 591                         */
 592                        map_remaining = skb->len;
 593                        subflow->map_data_len = skb->len;
 594                }
 595
 596                offset = seq - TCP_SKB_CB(skb)->seq;
 597                fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
 598                if (fin) {
 599                        done = true;
 600                        seq++;
 601                }
 602
 603                if (offset < skb->len) {
 604                        size_t len = skb->len - offset;
 605
 606                        if (tp->urg_data)
 607                                done = true;
 608
 609                        if (__mptcp_move_skb(msk, ssk, skb, offset, len))
 610                                moved += len;
 611                        seq += len;
 612
 613                        if (WARN_ON_ONCE(map_remaining < len))
 614                                break;
 615                } else {
 616                        WARN_ON_ONCE(!fin);
 617                        sk_eat_skb(ssk, skb);
 618                        done = true;
 619                }
 620
 621                WRITE_ONCE(tp->copied_seq, seq);
 622                more_data_avail = mptcp_subflow_data_available(ssk);
 623
 624                if (atomic_read(&sk->sk_rmem_alloc) > sk_rbuf) {
 625                        done = true;
 626                        break;
 627                }
 628        } while (more_data_avail);
 629
 630        *bytes += moved;
 631        return done;
 632}
 633
 634static bool __mptcp_ofo_queue(struct mptcp_sock *msk)
 635{
 636        struct sock *sk = (struct sock *)msk;
 637        struct sk_buff *skb, *tail;
 638        bool moved = false;
 639        struct rb_node *p;
 640        u64 end_seq;
 641
 642        p = rb_first(&msk->out_of_order_queue);
 643        pr_debug("msk=%p empty=%d", msk, RB_EMPTY_ROOT(&msk->out_of_order_queue));
 644        while (p) {
 645                skb = rb_to_skb(p);
 646                if (after64(MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq))
 647                        break;
 648
 649                p = rb_next(p);
 650                rb_erase(&skb->rbnode, &msk->out_of_order_queue);
 651
 652                if (unlikely(!after64(MPTCP_SKB_CB(skb)->end_seq,
 653                                      msk->ack_seq))) {
 654                        mptcp_drop(sk, skb);
 655                        MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
 656                        continue;
 657                }
 658
 659                end_seq = MPTCP_SKB_CB(skb)->end_seq;
 660                tail = skb_peek_tail(&sk->sk_receive_queue);
 661                if (!tail || !mptcp_ooo_try_coalesce(msk, tail, skb)) {
 662                        int delta = msk->ack_seq - MPTCP_SKB_CB(skb)->map_seq;
 663
 664                        /* skip overlapping data, if any */
 665                        pr_debug("uncoalesced seq=%llx ack seq=%llx delta=%d",
 666                                 MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq,
 667                                 delta);
 668                        MPTCP_SKB_CB(skb)->offset += delta;
 669                        __skb_queue_tail(&sk->sk_receive_queue, skb);
 670                }
 671                msk->ack_seq = end_seq;
 672                moved = true;
 673        }
 674        return moved;
 675}
 676
 677/* In most cases we will be able to lock the mptcp socket.  If its already
 678 * owned, we need to defer to the work queue to avoid ABBA deadlock.
 679 */
 680static bool move_skbs_to_msk(struct mptcp_sock *msk, struct sock *ssk)
 681{
 682        struct sock *sk = (struct sock *)msk;
 683        unsigned int moved = 0;
 684
 685        __mptcp_move_skbs_from_subflow(msk, ssk, &moved);
 686        __mptcp_ofo_queue(msk);
 687        if (unlikely(ssk->sk_err)) {
 688                if (!sock_owned_by_user(sk))
 689                        __mptcp_error_report(sk);
 690                else
 691                        set_bit(MPTCP_ERROR_REPORT,  &msk->flags);
 692        }
 693
 694        /* If the moves have caught up with the DATA_FIN sequence number
 695         * it's time to ack the DATA_FIN and change socket state, but
 696         * this is not a good place to change state. Let the workqueue
 697         * do it.
 698         */
 699        if (mptcp_pending_data_fin(sk, NULL))
 700                mptcp_schedule_work(sk);
 701        return moved > 0;
 702}
 703
 704void mptcp_data_ready(struct sock *sk, struct sock *ssk)
 705{
 706        struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 707        struct mptcp_sock *msk = mptcp_sk(sk);
 708        int sk_rbuf, ssk_rbuf;
 709
 710        /* The peer can send data while we are shutting down this
 711         * subflow at msk destruction time, but we must avoid enqueuing
 712         * more data to the msk receive queue
 713         */
 714        if (unlikely(subflow->disposable))
 715                return;
 716
 717        ssk_rbuf = READ_ONCE(ssk->sk_rcvbuf);
 718        sk_rbuf = READ_ONCE(sk->sk_rcvbuf);
 719        if (unlikely(ssk_rbuf > sk_rbuf))
 720                sk_rbuf = ssk_rbuf;
 721
 722        /* over limit? can't append more skbs to msk, Also, no need to wake-up*/
 723        if (__mptcp_rmem(sk) > sk_rbuf) {
 724                MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_RCVPRUNED);
 725                return;
 726        }
 727
 728        /* Wake-up the reader only for in-sequence data */
 729        mptcp_data_lock(sk);
 730        if (move_skbs_to_msk(msk, ssk)) {
 731                set_bit(MPTCP_DATA_READY, &msk->flags);
 732                sk->sk_data_ready(sk);
 733        }
 734        mptcp_data_unlock(sk);
 735}
 736
 737static bool mptcp_do_flush_join_list(struct mptcp_sock *msk)
 738{
 739        struct mptcp_subflow_context *subflow;
 740        bool ret = false;
 741
 742        if (likely(list_empty(&msk->join_list)))
 743                return false;
 744
 745        spin_lock_bh(&msk->join_list_lock);
 746        list_for_each_entry(subflow, &msk->join_list, node) {
 747                u32 sseq = READ_ONCE(subflow->setsockopt_seq);
 748
 749                mptcp_propagate_sndbuf((struct sock *)msk, mptcp_subflow_tcp_sock(subflow));
 750                if (READ_ONCE(msk->setsockopt_seq) != sseq)
 751                        ret = true;
 752        }
 753        list_splice_tail_init(&msk->join_list, &msk->conn_list);
 754        spin_unlock_bh(&msk->join_list_lock);
 755
 756        return ret;
 757}
 758
 759void __mptcp_flush_join_list(struct mptcp_sock *msk)
 760{
 761        if (likely(!mptcp_do_flush_join_list(msk)))
 762                return;
 763
 764        if (!test_and_set_bit(MPTCP_WORK_SYNC_SETSOCKOPT, &msk->flags))
 765                mptcp_schedule_work((struct sock *)msk);
 766}
 767
 768static void mptcp_flush_join_list(struct mptcp_sock *msk)
 769{
 770        bool sync_needed = test_and_clear_bit(MPTCP_WORK_SYNC_SETSOCKOPT, &msk->flags);
 771
 772        might_sleep();
 773
 774        if (!mptcp_do_flush_join_list(msk) && !sync_needed)
 775                return;
 776
 777        mptcp_sockopt_sync_all(msk);
 778}
 779
 780static bool mptcp_timer_pending(struct sock *sk)
 781{
 782        return timer_pending(&inet_csk(sk)->icsk_retransmit_timer);
 783}
 784
 785static void mptcp_reset_timer(struct sock *sk)
 786{
 787        struct inet_connection_sock *icsk = inet_csk(sk);
 788        unsigned long tout;
 789
 790        /* prevent rescheduling on close */
 791        if (unlikely(inet_sk_state_load(sk) == TCP_CLOSE))
 792                return;
 793
 794        /* should never be called with mptcp level timer cleared */
 795        tout = READ_ONCE(mptcp_sk(sk)->timer_ival);
 796        if (WARN_ON_ONCE(!tout))
 797                tout = TCP_RTO_MIN;
 798        sk_reset_timer(sk, &icsk->icsk_retransmit_timer, jiffies + tout);
 799}
 800
 801bool mptcp_schedule_work(struct sock *sk)
 802{
 803        if (inet_sk_state_load(sk) != TCP_CLOSE &&
 804            schedule_work(&mptcp_sk(sk)->work)) {
 805                /* each subflow already holds a reference to the sk, and the
 806                 * workqueue is invoked by a subflow, so sk can't go away here.
 807                 */
 808                sock_hold(sk);
 809                return true;
 810        }
 811        return false;
 812}
 813
 814void mptcp_subflow_eof(struct sock *sk)
 815{
 816        if (!test_and_set_bit(MPTCP_WORK_EOF, &mptcp_sk(sk)->flags))
 817                mptcp_schedule_work(sk);
 818}
 819
 820static void mptcp_check_for_eof(struct mptcp_sock *msk)
 821{
 822        struct mptcp_subflow_context *subflow;
 823        struct sock *sk = (struct sock *)msk;
 824        int receivers = 0;
 825
 826        mptcp_for_each_subflow(msk, subflow)
 827                receivers += !subflow->rx_eof;
 828        if (receivers)
 829                return;
 830
 831        if (!(sk->sk_shutdown & RCV_SHUTDOWN)) {
 832                /* hopefully temporary hack: propagate shutdown status
 833                 * to msk, when all subflows agree on it
 834                 */
 835                sk->sk_shutdown |= RCV_SHUTDOWN;
 836
 837                smp_mb__before_atomic(); /* SHUTDOWN must be visible first */
 838                set_bit(MPTCP_DATA_READY, &msk->flags);
 839                sk->sk_data_ready(sk);
 840        }
 841
 842        switch (sk->sk_state) {
 843        case TCP_ESTABLISHED:
 844                inet_sk_state_store(sk, TCP_CLOSE_WAIT);
 845                break;
 846        case TCP_FIN_WAIT1:
 847                inet_sk_state_store(sk, TCP_CLOSING);
 848                break;
 849        case TCP_FIN_WAIT2:
 850                inet_sk_state_store(sk, TCP_CLOSE);
 851                break;
 852        default:
 853                return;
 854        }
 855        mptcp_close_wake_up(sk);
 856}
 857
 858static struct sock *mptcp_subflow_recv_lookup(const struct mptcp_sock *msk)
 859{
 860        struct mptcp_subflow_context *subflow;
 861        struct sock *sk = (struct sock *)msk;
 862
 863        sock_owned_by_me(sk);
 864
 865        mptcp_for_each_subflow(msk, subflow) {
 866                if (READ_ONCE(subflow->data_avail))
 867                        return mptcp_subflow_tcp_sock(subflow);
 868        }
 869
 870        return NULL;
 871}
 872
 873static bool mptcp_skb_can_collapse_to(u64 write_seq,
 874                                      const struct sk_buff *skb,
 875                                      const struct mptcp_ext *mpext)
 876{
 877        if (!tcp_skb_can_collapse_to(skb))
 878                return false;
 879
 880        /* can collapse only if MPTCP level sequence is in order and this
 881         * mapping has not been xmitted yet
 882         */
 883        return mpext && mpext->data_seq + mpext->data_len == write_seq &&
 884               !mpext->frozen;
 885}
 886
 887/* we can append data to the given data frag if:
 888 * - there is space available in the backing page_frag
 889 * - the data frag tail matches the current page_frag free offset
 890 * - the data frag end sequence number matches the current write seq
 891 */
 892static bool mptcp_frag_can_collapse_to(const struct mptcp_sock *msk,
 893                                       const struct page_frag *pfrag,
 894                                       const struct mptcp_data_frag *df)
 895{
 896        return df && pfrag->page == df->page &&
 897                pfrag->size - pfrag->offset > 0 &&
 898                pfrag->offset == (df->offset + df->data_len) &&
 899                df->data_seq + df->data_len == msk->write_seq;
 900}
 901
 902static int mptcp_wmem_with_overhead(int size)
 903{
 904        return size + ((sizeof(struct mptcp_data_frag) * size) >> PAGE_SHIFT);
 905}
 906
 907static void __mptcp_wmem_reserve(struct sock *sk, int size)
 908{
 909        int amount = mptcp_wmem_with_overhead(size);
 910        struct mptcp_sock *msk = mptcp_sk(sk);
 911
 912        WARN_ON_ONCE(msk->wmem_reserved);
 913        if (WARN_ON_ONCE(amount < 0))
 914                amount = 0;
 915
 916        if (amount <= sk->sk_forward_alloc)
 917                goto reserve;
 918
 919        /* under memory pressure try to reserve at most a single page
 920         * otherwise try to reserve the full estimate and fallback
 921         * to a single page before entering the error path
 922         */
 923        if ((tcp_under_memory_pressure(sk) && amount > PAGE_SIZE) ||
 924            !sk_wmem_schedule(sk, amount)) {
 925                if (amount <= PAGE_SIZE)
 926                        goto nomem;
 927
 928                amount = PAGE_SIZE;
 929                if (!sk_wmem_schedule(sk, amount))
 930                        goto nomem;
 931        }
 932
 933reserve:
 934        msk->wmem_reserved = amount;
 935        sk->sk_forward_alloc -= amount;
 936        return;
 937
 938nomem:
 939        /* we will wait for memory on next allocation */
 940        msk->wmem_reserved = -1;
 941}
 942
 943static void __mptcp_update_wmem(struct sock *sk)
 944{
 945        struct mptcp_sock *msk = mptcp_sk(sk);
 946
 947#ifdef CONFIG_LOCKDEP
 948        WARN_ON_ONCE(!lockdep_is_held(&sk->sk_lock.slock));
 949#endif
 950
 951        if (!msk->wmem_reserved)
 952                return;
 953
 954        if (msk->wmem_reserved < 0)
 955                msk->wmem_reserved = 0;
 956        if (msk->wmem_reserved > 0) {
 957                sk->sk_forward_alloc += msk->wmem_reserved;
 958                msk->wmem_reserved = 0;
 959        }
 960}
 961
 962static bool mptcp_wmem_alloc(struct sock *sk, int size)
 963{
 964        struct mptcp_sock *msk = mptcp_sk(sk);
 965
 966        /* check for pre-existing error condition */
 967        if (msk->wmem_reserved < 0)
 968                return false;
 969
 970        if (msk->wmem_reserved >= size)
 971                goto account;
 972
 973        mptcp_data_lock(sk);
 974        if (!sk_wmem_schedule(sk, size)) {
 975                mptcp_data_unlock(sk);
 976                return false;
 977        }
 978
 979        sk->sk_forward_alloc -= size;
 980        msk->wmem_reserved += size;
 981        mptcp_data_unlock(sk);
 982
 983account:
 984        msk->wmem_reserved -= size;
 985        return true;
 986}
 987
 988static void mptcp_wmem_uncharge(struct sock *sk, int size)
 989{
 990        struct mptcp_sock *msk = mptcp_sk(sk);
 991
 992        if (msk->wmem_reserved < 0)
 993                msk->wmem_reserved = 0;
 994        msk->wmem_reserved += size;
 995}
 996
 997static void mptcp_mem_reclaim_partial(struct sock *sk)
 998{
 999        struct mptcp_sock *msk = mptcp_sk(sk);
1000
1001        /* if we are experiencing a transint allocation error,
1002         * the forward allocation memory has been already
1003         * released
1004         */
1005        if (msk->wmem_reserved < 0)
1006                return;
1007
1008        mptcp_data_lock(sk);
1009        sk->sk_forward_alloc += msk->wmem_reserved;
1010        sk_mem_reclaim_partial(sk);
1011        msk->wmem_reserved = sk->sk_forward_alloc;
1012        sk->sk_forward_alloc = 0;
1013        mptcp_data_unlock(sk);
1014}
1015
1016static void dfrag_uncharge(struct sock *sk, int len)
1017{
1018        sk_mem_uncharge(sk, len);
1019        sk_wmem_queued_add(sk, -len);
1020}
1021
1022static void dfrag_clear(struct sock *sk, struct mptcp_data_frag *dfrag)
1023{
1024        int len = dfrag->data_len + dfrag->overhead;
1025
1026        list_del(&dfrag->list);
1027        dfrag_uncharge(sk, len);
1028        put_page(dfrag->page);
1029}
1030
1031static void __mptcp_clean_una(struct sock *sk)
1032{
1033        struct mptcp_sock *msk = mptcp_sk(sk);
1034        struct mptcp_data_frag *dtmp, *dfrag;
1035        bool cleaned = false;
1036        u64 snd_una;
1037
1038        /* on fallback we just need to ignore snd_una, as this is really
1039         * plain TCP
1040         */
1041        if (__mptcp_check_fallback(msk))
1042                msk->snd_una = READ_ONCE(msk->snd_nxt);
1043
1044        snd_una = msk->snd_una;
1045        list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list) {
1046                if (after64(dfrag->data_seq + dfrag->data_len, snd_una))
1047                        break;
1048
1049                if (WARN_ON_ONCE(dfrag == msk->first_pending))
1050                        break;
1051                dfrag_clear(sk, dfrag);
1052                cleaned = true;
1053        }
1054
1055        dfrag = mptcp_rtx_head(sk);
1056        if (dfrag && after64(snd_una, dfrag->data_seq)) {
1057                u64 delta = snd_una - dfrag->data_seq;
1058
1059                if (WARN_ON_ONCE(delta > dfrag->already_sent))
1060                        goto out;
1061
1062                dfrag->data_seq += delta;
1063                dfrag->offset += delta;
1064                dfrag->data_len -= delta;
1065                dfrag->already_sent -= delta;
1066
1067                dfrag_uncharge(sk, delta);
1068                cleaned = true;
1069        }
1070
1071out:
1072        if (cleaned) {
1073                if (tcp_under_memory_pressure(sk)) {
1074                        __mptcp_update_wmem(sk);
1075                        sk_mem_reclaim_partial(sk);
1076                }
1077        }
1078
1079        if (snd_una == READ_ONCE(msk->snd_nxt)) {
1080                if (msk->timer_ival && !mptcp_data_fin_enabled(msk))
1081                        mptcp_stop_timer(sk);
1082        } else {
1083                mptcp_reset_timer(sk);
1084        }
1085}
1086
1087static void __mptcp_clean_una_wakeup(struct sock *sk)
1088{
1089#ifdef CONFIG_LOCKDEP
1090        WARN_ON_ONCE(!lockdep_is_held(&sk->sk_lock.slock));
1091#endif
1092        __mptcp_clean_una(sk);
1093        mptcp_write_space(sk);
1094}
1095
1096static void mptcp_clean_una_wakeup(struct sock *sk)
1097{
1098        mptcp_data_lock(sk);
1099        __mptcp_clean_una_wakeup(sk);
1100        mptcp_data_unlock(sk);
1101}
1102
1103static void mptcp_enter_memory_pressure(struct sock *sk)
1104{
1105        struct mptcp_subflow_context *subflow;
1106        struct mptcp_sock *msk = mptcp_sk(sk);
1107        bool first = true;
1108
1109        sk_stream_moderate_sndbuf(sk);
1110        mptcp_for_each_subflow(msk, subflow) {
1111                struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
1112
1113                if (first)
1114                        tcp_enter_memory_pressure(ssk);
1115                sk_stream_moderate_sndbuf(ssk);
1116                first = false;
1117        }
1118}
1119
1120/* ensure we get enough memory for the frag hdr, beyond some minimal amount of
1121 * data
1122 */
1123static bool mptcp_page_frag_refill(struct sock *sk, struct page_frag *pfrag)
1124{
1125        if (likely(skb_page_frag_refill(32U + sizeof(struct mptcp_data_frag),
1126                                        pfrag, sk->sk_allocation)))
1127                return true;
1128
1129        mptcp_enter_memory_pressure(sk);
1130        return false;
1131}
1132
1133static struct mptcp_data_frag *
1134mptcp_carve_data_frag(const struct mptcp_sock *msk, struct page_frag *pfrag,
1135                      int orig_offset)
1136{
1137        int offset = ALIGN(orig_offset, sizeof(long));
1138        struct mptcp_data_frag *dfrag;
1139
1140        dfrag = (struct mptcp_data_frag *)(page_to_virt(pfrag->page) + offset);
1141        dfrag->data_len = 0;
1142        dfrag->data_seq = msk->write_seq;
1143        dfrag->overhead = offset - orig_offset + sizeof(struct mptcp_data_frag);
1144        dfrag->offset = offset + sizeof(struct mptcp_data_frag);
1145        dfrag->already_sent = 0;
1146        dfrag->page = pfrag->page;
1147
1148        return dfrag;
1149}
1150
1151struct mptcp_sendmsg_info {
1152        int mss_now;
1153        int size_goal;
1154        u16 limit;
1155        u16 sent;
1156        unsigned int flags;
1157};
1158
1159static int mptcp_check_allowed_size(struct mptcp_sock *msk, u64 data_seq,
1160                                    int avail_size)
1161{
1162        u64 window_end = mptcp_wnd_end(msk);
1163
1164        if (__mptcp_check_fallback(msk))
1165                return avail_size;
1166
1167        if (!before64(data_seq + avail_size, window_end)) {
1168                u64 allowed_size = window_end - data_seq;
1169
1170                return min_t(unsigned int, allowed_size, avail_size);
1171        }
1172
1173        return avail_size;
1174}
1175
1176static bool __mptcp_add_ext(struct sk_buff *skb, gfp_t gfp)
1177{
1178        struct skb_ext *mpext = __skb_ext_alloc(gfp);
1179
1180        if (!mpext)
1181                return false;
1182        __skb_ext_set(skb, SKB_EXT_MPTCP, mpext);
1183        return true;
1184}
1185
1186static struct sk_buff *__mptcp_do_alloc_tx_skb(struct sock *sk, gfp_t gfp)
1187{
1188        struct sk_buff *skb;
1189
1190        skb = alloc_skb_fclone(MAX_TCP_HEADER, gfp);
1191        if (likely(skb)) {
1192                if (likely(__mptcp_add_ext(skb, gfp))) {
1193                        skb_reserve(skb, MAX_TCP_HEADER);
1194                        skb->reserved_tailroom = skb->end - skb->tail;
1195                        return skb;
1196                }
1197                __kfree_skb(skb);
1198        } else {
1199                mptcp_enter_memory_pressure(sk);
1200        }
1201        return NULL;
1202}
1203
1204static bool __mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, gfp_t gfp)
1205{
1206        struct sk_buff *skb;
1207
1208        if (ssk->sk_tx_skb_cache) {
1209                skb = ssk->sk_tx_skb_cache;
1210                if (unlikely(!skb_ext_find(skb, SKB_EXT_MPTCP) &&
1211                             !__mptcp_add_ext(skb, gfp)))
1212                        return false;
1213                return true;
1214        }
1215
1216        skb = __mptcp_do_alloc_tx_skb(sk, gfp);
1217        if (!skb)
1218                return false;
1219
1220        if (likely(sk_wmem_schedule(ssk, skb->truesize))) {
1221                ssk->sk_tx_skb_cache = skb;
1222                return true;
1223        }
1224        kfree_skb(skb);
1225        return false;
1226}
1227
1228static bool mptcp_must_reclaim_memory(struct sock *sk, struct sock *ssk)
1229{
1230        return !ssk->sk_tx_skb_cache &&
1231               tcp_under_memory_pressure(sk);
1232}
1233
1234static bool mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk)
1235{
1236        if (unlikely(mptcp_must_reclaim_memory(sk, ssk)))
1237                mptcp_mem_reclaim_partial(sk);
1238        return __mptcp_alloc_tx_skb(sk, ssk, sk->sk_allocation);
1239}
1240
1241/* note: this always recompute the csum on the whole skb, even
1242 * if we just appended a single frag. More status info needed
1243 */
1244static void mptcp_update_data_checksum(struct sk_buff *skb, int added)
1245{
1246        struct mptcp_ext *mpext = mptcp_get_ext(skb);
1247        __wsum csum = ~csum_unfold(mpext->csum);
1248        int offset = skb->len - added;
1249
1250        mpext->csum = csum_fold(csum_block_add(csum, skb_checksum(skb, offset, added, 0), offset));
1251}
1252
1253static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
1254                              struct mptcp_data_frag *dfrag,
1255                              struct mptcp_sendmsg_info *info)
1256{
1257        u64 data_seq = dfrag->data_seq + info->sent;
1258        struct mptcp_sock *msk = mptcp_sk(sk);
1259        bool zero_window_probe = false;
1260        struct mptcp_ext *mpext = NULL;
1261        struct sk_buff *skb, *tail;
1262        bool can_collapse = false;
1263        int size_bias = 0;
1264        int avail_size;
1265        size_t ret = 0;
1266
1267        pr_debug("msk=%p ssk=%p sending dfrag at seq=%llu len=%u already sent=%u",
1268                 msk, ssk, dfrag->data_seq, dfrag->data_len, info->sent);
1269
1270        /* compute send limit */
1271        info->mss_now = tcp_send_mss(ssk, &info->size_goal, info->flags);
1272        avail_size = info->size_goal;
1273        skb = tcp_write_queue_tail(ssk);
1274        if (skb) {
1275                /* Limit the write to the size available in the
1276                 * current skb, if any, so that we create at most a new skb.
1277                 * Explicitly tells TCP internals to avoid collapsing on later
1278                 * queue management operation, to avoid breaking the ext <->
1279                 * SSN association set here
1280                 */
1281                mpext = skb_ext_find(skb, SKB_EXT_MPTCP);
1282                can_collapse = (info->size_goal - skb->len > 0) &&
1283                         mptcp_skb_can_collapse_to(data_seq, skb, mpext);
1284                if (!can_collapse) {
1285                        TCP_SKB_CB(skb)->eor = 1;
1286                } else {
1287                        size_bias = skb->len;
1288                        avail_size = info->size_goal - skb->len;
1289                }
1290        }
1291
1292        /* Zero window and all data acked? Probe. */
1293        avail_size = mptcp_check_allowed_size(msk, data_seq, avail_size);
1294        if (avail_size == 0) {
1295                u64 snd_una = READ_ONCE(msk->snd_una);
1296
1297                if (skb || snd_una != msk->snd_nxt)
1298                        return 0;
1299                zero_window_probe = true;
1300                data_seq = snd_una - 1;
1301                avail_size = 1;
1302        }
1303
1304        if (WARN_ON_ONCE(info->sent > info->limit ||
1305                         info->limit > dfrag->data_len))
1306                return 0;
1307
1308        ret = info->limit - info->sent;
1309        tail = tcp_build_frag(ssk, avail_size + size_bias, info->flags,
1310                              dfrag->page, dfrag->offset + info->sent, &ret);
1311        if (!tail) {
1312                tcp_remove_empty_skb(sk, tcp_write_queue_tail(ssk));
1313                return -ENOMEM;
1314        }
1315
1316        /* if the tail skb is still the cached one, collapsing really happened.
1317         */
1318        if (skb == tail) {
1319                TCP_SKB_CB(tail)->tcp_flags &= ~TCPHDR_PSH;
1320                mpext->data_len += ret;
1321                WARN_ON_ONCE(!can_collapse);
1322                WARN_ON_ONCE(zero_window_probe);
1323                goto out;
1324        }
1325
1326        mpext = skb_ext_find(tail, SKB_EXT_MPTCP);
1327        if (WARN_ON_ONCE(!mpext)) {
1328                /* should never reach here, stream corrupted */
1329                return -EINVAL;
1330        }
1331
1332        memset(mpext, 0, sizeof(*mpext));
1333        mpext->data_seq = data_seq;
1334        mpext->subflow_seq = mptcp_subflow_ctx(ssk)->rel_write_seq;
1335        mpext->data_len = ret;
1336        mpext->use_map = 1;
1337        mpext->dsn64 = 1;
1338
1339        pr_debug("data_seq=%llu subflow_seq=%u data_len=%u dsn64=%d",
1340                 mpext->data_seq, mpext->subflow_seq, mpext->data_len,
1341                 mpext->dsn64);
1342
1343        if (zero_window_probe) {
1344                mptcp_subflow_ctx(ssk)->rel_write_seq += ret;
1345                mpext->frozen = 1;
1346                if (READ_ONCE(msk->csum_enabled))
1347                        mptcp_update_data_checksum(tail, ret);
1348                tcp_push_pending_frames(ssk);
1349                return 0;
1350        }
1351out:
1352        if (READ_ONCE(msk->csum_enabled))
1353                mptcp_update_data_checksum(tail, ret);
1354        mptcp_subflow_ctx(ssk)->rel_write_seq += ret;
1355        return ret;
1356}
1357
1358#define MPTCP_SEND_BURST_SIZE           ((1 << 16) - \
1359                                         sizeof(struct tcphdr) - \
1360                                         MAX_TCP_OPTION_SPACE - \
1361                                         sizeof(struct ipv6hdr) - \
1362                                         sizeof(struct frag_hdr))
1363
1364struct subflow_send_info {
1365        struct sock *ssk;
1366        u64 ratio;
1367};
1368
1369static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
1370{
1371        struct subflow_send_info send_info[2];
1372        struct mptcp_subflow_context *subflow;
1373        int i, nr_active = 0;
1374        struct sock *ssk;
1375        u64 ratio;
1376        u32 pace;
1377
1378        sock_owned_by_me((struct sock *)msk);
1379
1380        if (__mptcp_check_fallback(msk)) {
1381                if (!msk->first)
1382                        return NULL;
1383                return sk_stream_memory_free(msk->first) ? msk->first : NULL;
1384        }
1385
1386        /* re-use last subflow, if the burst allow that */
1387        if (msk->last_snd && msk->snd_burst > 0 &&
1388            sk_stream_memory_free(msk->last_snd) &&
1389            mptcp_subflow_active(mptcp_subflow_ctx(msk->last_snd)))
1390                return msk->last_snd;
1391
1392        /* pick the subflow with the lower wmem/wspace ratio */
1393        for (i = 0; i < 2; ++i) {
1394                send_info[i].ssk = NULL;
1395                send_info[i].ratio = -1;
1396        }
1397        mptcp_for_each_subflow(msk, subflow) {
1398                trace_mptcp_subflow_get_send(subflow);
1399                ssk =  mptcp_subflow_tcp_sock(subflow);
1400                if (!mptcp_subflow_active(subflow))
1401                        continue;
1402
1403                nr_active += !subflow->backup;
1404                if (!sk_stream_memory_free(subflow->tcp_sock) || !tcp_sk(ssk)->snd_wnd)
1405                        continue;
1406
1407                pace = READ_ONCE(ssk->sk_pacing_rate);
1408                if (!pace)
1409                        continue;
1410
1411                ratio = div_u64((u64)READ_ONCE(ssk->sk_wmem_queued) << 32,
1412                                pace);
1413                if (ratio < send_info[subflow->backup].ratio) {
1414                        send_info[subflow->backup].ssk = ssk;
1415                        send_info[subflow->backup].ratio = ratio;
1416                }
1417        }
1418
1419        /* pick the best backup if no other subflow is active */
1420        if (!nr_active)
1421                send_info[0].ssk = send_info[1].ssk;
1422
1423        if (send_info[0].ssk) {
1424                msk->last_snd = send_info[0].ssk;
1425                msk->snd_burst = min_t(int, MPTCP_SEND_BURST_SIZE,
1426                                       tcp_sk(msk->last_snd)->snd_wnd);
1427                return msk->last_snd;
1428        }
1429
1430        return NULL;
1431}
1432
1433static void mptcp_push_release(struct sock *sk, struct sock *ssk,
1434                               struct mptcp_sendmsg_info *info)
1435{
1436        mptcp_set_timeout(sk, ssk);
1437        tcp_push(ssk, 0, info->mss_now, tcp_sk(ssk)->nonagle, info->size_goal);
1438        release_sock(ssk);
1439}
1440
1441static void __mptcp_push_pending(struct sock *sk, unsigned int flags)
1442{
1443        struct sock *prev_ssk = NULL, *ssk = NULL;
1444        struct mptcp_sock *msk = mptcp_sk(sk);
1445        struct mptcp_sendmsg_info info = {
1446                                .flags = flags,
1447        };
1448        struct mptcp_data_frag *dfrag;
1449        int len, copied = 0;
1450
1451        while ((dfrag = mptcp_send_head(sk))) {
1452                info.sent = dfrag->already_sent;
1453                info.limit = dfrag->data_len;
1454                len = dfrag->data_len - dfrag->already_sent;
1455                while (len > 0) {
1456                        int ret = 0;
1457
1458                        prev_ssk = ssk;
1459                        mptcp_flush_join_list(msk);
1460                        ssk = mptcp_subflow_get_send(msk);
1461
1462                        /* try to keep the subflow socket lock across
1463                         * consecutive xmit on the same socket
1464                         */
1465                        if (ssk != prev_ssk && prev_ssk)
1466                                mptcp_push_release(sk, prev_ssk, &info);
1467                        if (!ssk)
1468                                goto out;
1469
1470                        if (ssk != prev_ssk || !prev_ssk)
1471                                lock_sock(ssk);
1472
1473                        /* keep it simple and always provide a new skb for the
1474                         * subflow, even if we will not use it when collapsing
1475                         * on the pending one
1476                         */
1477                        if (!mptcp_alloc_tx_skb(sk, ssk)) {
1478                                mptcp_push_release(sk, ssk, &info);
1479                                goto out;
1480                        }
1481
1482                        ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info);
1483                        if (ret <= 0) {
1484                                mptcp_push_release(sk, ssk, &info);
1485                                goto out;
1486                        }
1487
1488                        info.sent += ret;
1489                        dfrag->already_sent += ret;
1490                        msk->snd_nxt += ret;
1491                        msk->snd_burst -= ret;
1492                        msk->tx_pending_data -= ret;
1493                        copied += ret;
1494                        len -= ret;
1495                }
1496                WRITE_ONCE(msk->first_pending, mptcp_send_next(sk));
1497        }
1498
1499        /* at this point we held the socket lock for the last subflow we used */
1500        if (ssk)
1501                mptcp_push_release(sk, ssk, &info);
1502
1503out:
1504        if (copied) {
1505                /* start the timer, if it's not pending */
1506                if (!mptcp_timer_pending(sk))
1507                        mptcp_reset_timer(sk);
1508                __mptcp_check_send_data_fin(sk);
1509        }
1510}
1511
1512static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk)
1513{
1514        struct mptcp_sock *msk = mptcp_sk(sk);
1515        struct mptcp_sendmsg_info info;
1516        struct mptcp_data_frag *dfrag;
1517        struct sock *xmit_ssk;
1518        int len, copied = 0;
1519        bool first = true;
1520
1521        info.flags = 0;
1522        while ((dfrag = mptcp_send_head(sk))) {
1523                info.sent = dfrag->already_sent;
1524                info.limit = dfrag->data_len;
1525                len = dfrag->data_len - dfrag->already_sent;
1526                while (len > 0) {
1527                        int ret = 0;
1528
1529                        /* the caller already invoked the packet scheduler,
1530                         * check for a different subflow usage only after
1531                         * spooling the first chunk of data
1532                         */
1533                        xmit_ssk = first ? ssk : mptcp_subflow_get_send(mptcp_sk(sk));
1534                        if (!xmit_ssk)
1535                                goto out;
1536                        if (xmit_ssk != ssk) {
1537                                mptcp_subflow_delegate(mptcp_subflow_ctx(xmit_ssk));
1538                                goto out;
1539                        }
1540
1541                        if (unlikely(mptcp_must_reclaim_memory(sk, ssk))) {
1542                                __mptcp_update_wmem(sk);
1543                                sk_mem_reclaim_partial(sk);
1544                        }
1545                        if (!__mptcp_alloc_tx_skb(sk, ssk, GFP_ATOMIC))
1546                                goto out;
1547
1548                        ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info);
1549                        if (ret <= 0)
1550                                goto out;
1551
1552                        info.sent += ret;
1553                        dfrag->already_sent += ret;
1554                        msk->snd_nxt += ret;
1555                        msk->snd_burst -= ret;
1556                        msk->tx_pending_data -= ret;
1557                        copied += ret;
1558                        len -= ret;
1559                        first = false;
1560                }
1561                WRITE_ONCE(msk->first_pending, mptcp_send_next(sk));
1562        }
1563
1564out:
1565        /* __mptcp_alloc_tx_skb could have released some wmem and we are
1566         * not going to flush it via release_sock()
1567         */
1568        __mptcp_update_wmem(sk);
1569        if (copied) {
1570                mptcp_set_timeout(sk, ssk);
1571                tcp_push(ssk, 0, info.mss_now, tcp_sk(ssk)->nonagle,
1572                         info.size_goal);
1573                if (!mptcp_timer_pending(sk))
1574                        mptcp_reset_timer(sk);
1575
1576                if (msk->snd_data_fin_enable &&
1577                    msk->snd_nxt + 1 == msk->write_seq)
1578                        mptcp_schedule_work(sk);
1579        }
1580}
1581
1582static void mptcp_set_nospace(struct sock *sk)
1583{
1584        /* enable autotune */
1585        set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
1586
1587        /* will be cleared on avail space */
1588        set_bit(MPTCP_NOSPACE, &mptcp_sk(sk)->flags);
1589}
1590
1591static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
1592{
1593        struct mptcp_sock *msk = mptcp_sk(sk);
1594        struct page_frag *pfrag;
1595        size_t copied = 0;
1596        int ret = 0;
1597        long timeo;
1598
1599        /* we don't support FASTOPEN yet */
1600        if (msg->msg_flags & MSG_FASTOPEN)
1601                return -EOPNOTSUPP;
1602
1603        /* silently ignore everything else */
1604        msg->msg_flags &= MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL;
1605
1606        mptcp_lock_sock(sk, __mptcp_wmem_reserve(sk, min_t(size_t, 1 << 20, len)));
1607
1608        timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
1609
1610        if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) {
1611                ret = sk_stream_wait_connect(sk, &timeo);
1612                if (ret)
1613                        goto out;
1614        }
1615
1616        pfrag = sk_page_frag(sk);
1617
1618        while (msg_data_left(msg)) {
1619                int total_ts, frag_truesize = 0;
1620                struct mptcp_data_frag *dfrag;
1621                bool dfrag_collapsed;
1622                size_t psize, offset;
1623
1624                if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) {
1625                        ret = -EPIPE;
1626                        goto out;
1627                }
1628
1629                /* reuse tail pfrag, if possible, or carve a new one from the
1630                 * page allocator
1631                 */
1632                dfrag = mptcp_pending_tail(sk);
1633                dfrag_collapsed = mptcp_frag_can_collapse_to(msk, pfrag, dfrag);
1634                if (!dfrag_collapsed) {
1635                        if (!sk_stream_memory_free(sk))
1636                                goto wait_for_memory;
1637
1638                        if (!mptcp_page_frag_refill(sk, pfrag))
1639                                goto wait_for_memory;
1640
1641                        dfrag = mptcp_carve_data_frag(msk, pfrag, pfrag->offset);
1642                        frag_truesize = dfrag->overhead;
1643                }
1644
1645                /* we do not bound vs wspace, to allow a single packet.
1646                 * memory accounting will prevent execessive memory usage
1647                 * anyway
1648                 */
1649                offset = dfrag->offset + dfrag->data_len;
1650                psize = pfrag->size - offset;
1651                psize = min_t(size_t, psize, msg_data_left(msg));
1652                total_ts = psize + frag_truesize;
1653
1654                if (!mptcp_wmem_alloc(sk, total_ts))
1655                        goto wait_for_memory;
1656
1657                if (copy_page_from_iter(dfrag->page, offset, psize,
1658                                        &msg->msg_iter) != psize) {
1659                        mptcp_wmem_uncharge(sk, psize + frag_truesize);
1660                        ret = -EFAULT;
1661                        goto out;
1662                }
1663
1664                /* data successfully copied into the write queue */
1665                copied += psize;
1666                dfrag->data_len += psize;
1667                frag_truesize += psize;
1668                pfrag->offset += frag_truesize;
1669                WRITE_ONCE(msk->write_seq, msk->write_seq + psize);
1670                msk->tx_pending_data += psize;
1671
1672                /* charge data on mptcp pending queue to the msk socket
1673                 * Note: we charge such data both to sk and ssk
1674                 */
1675                sk_wmem_queued_add(sk, frag_truesize);
1676                if (!dfrag_collapsed) {
1677                        get_page(dfrag->page);
1678                        list_add_tail(&dfrag->list, &msk->rtx_queue);
1679                        if (!msk->first_pending)
1680                                WRITE_ONCE(msk->first_pending, dfrag);
1681                }
1682                pr_debug("msk=%p dfrag at seq=%llu len=%u sent=%u new=%d", msk,
1683                         dfrag->data_seq, dfrag->data_len, dfrag->already_sent,
1684                         !dfrag_collapsed);
1685
1686                continue;
1687
1688wait_for_memory:
1689                mptcp_set_nospace(sk);
1690                __mptcp_push_pending(sk, msg->msg_flags);
1691                ret = sk_stream_wait_memory(sk, &timeo);
1692                if (ret)
1693                        goto out;
1694        }
1695
1696        if (copied)
1697                __mptcp_push_pending(sk, msg->msg_flags);
1698
1699out:
1700        release_sock(sk);
1701        return copied ? : ret;
1702}
1703
1704static void mptcp_wait_data(struct sock *sk, long *timeo)
1705{
1706        DEFINE_WAIT_FUNC(wait, woken_wake_function);
1707        struct mptcp_sock *msk = mptcp_sk(sk);
1708
1709        add_wait_queue(sk_sleep(sk), &wait);
1710        sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
1711
1712        sk_wait_event(sk, timeo,
1713                      test_bit(MPTCP_DATA_READY, &msk->flags), &wait);
1714
1715        sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
1716        remove_wait_queue(sk_sleep(sk), &wait);
1717}
1718
1719static int __mptcp_recvmsg_mskq(struct mptcp_sock *msk,
1720                                struct msghdr *msg,
1721                                size_t len, int flags,
1722                                struct scm_timestamping_internal *tss,
1723                                int *cmsg_flags)
1724{
1725        struct sk_buff *skb, *tmp;
1726        int copied = 0;
1727
1728        skb_queue_walk_safe(&msk->receive_queue, skb, tmp) {
1729                u32 offset = MPTCP_SKB_CB(skb)->offset;
1730                u32 data_len = skb->len - offset;
1731                u32 count = min_t(size_t, len - copied, data_len);
1732                int err;
1733
1734                if (!(flags & MSG_TRUNC)) {
1735                        err = skb_copy_datagram_msg(skb, offset, msg, count);
1736                        if (unlikely(err < 0)) {
1737                                if (!copied)
1738                                        return err;
1739                                break;
1740                        }
1741                }
1742
1743                if (MPTCP_SKB_CB(skb)->has_rxtstamp) {
1744                        tcp_update_recv_tstamps(skb, tss);
1745                        *cmsg_flags |= MPTCP_CMSG_TS;
1746                }
1747
1748                copied += count;
1749
1750                if (count < data_len) {
1751                        if (!(flags & MSG_PEEK))
1752                                MPTCP_SKB_CB(skb)->offset += count;
1753                        break;
1754                }
1755
1756                if (!(flags & MSG_PEEK)) {
1757                        /* we will bulk release the skb memory later */
1758                        skb->destructor = NULL;
1759                        WRITE_ONCE(msk->rmem_released, msk->rmem_released + skb->truesize);
1760                        __skb_unlink(skb, &msk->receive_queue);
1761                        __kfree_skb(skb);
1762                }
1763
1764                if (copied >= len)
1765                        break;
1766        }
1767
1768        return copied;
1769}
1770
1771/* receive buffer autotuning.  See tcp_rcv_space_adjust for more information.
1772 *
1773 * Only difference: Use highest rtt estimate of the subflows in use.
1774 */
1775static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied)
1776{
1777        struct mptcp_subflow_context *subflow;
1778        struct sock *sk = (struct sock *)msk;
1779        u32 time, advmss = 1;
1780        u64 rtt_us, mstamp;
1781
1782        sock_owned_by_me(sk);
1783
1784        if (copied <= 0)
1785                return;
1786
1787        msk->rcvq_space.copied += copied;
1788
1789        mstamp = div_u64(tcp_clock_ns(), NSEC_PER_USEC);
1790        time = tcp_stamp_us_delta(mstamp, msk->rcvq_space.time);
1791
1792        rtt_us = msk->rcvq_space.rtt_us;
1793        if (rtt_us && time < (rtt_us >> 3))
1794                return;
1795
1796        rtt_us = 0;
1797        mptcp_for_each_subflow(msk, subflow) {
1798                const struct tcp_sock *tp;
1799                u64 sf_rtt_us;
1800                u32 sf_advmss;
1801
1802                tp = tcp_sk(mptcp_subflow_tcp_sock(subflow));
1803
1804                sf_rtt_us = READ_ONCE(tp->rcv_rtt_est.rtt_us);
1805                sf_advmss = READ_ONCE(tp->advmss);
1806
1807                rtt_us = max(sf_rtt_us, rtt_us);
1808                advmss = max(sf_advmss, advmss);
1809        }
1810
1811        msk->rcvq_space.rtt_us = rtt_us;
1812        if (time < (rtt_us >> 3) || rtt_us == 0)
1813                return;
1814
1815        if (msk->rcvq_space.copied <= msk->rcvq_space.space)
1816                goto new_measure;
1817
1818        if (sock_net(sk)->ipv4.sysctl_tcp_moderate_rcvbuf &&
1819            !(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
1820                int rcvmem, rcvbuf;
1821                u64 rcvwin, grow;
1822
1823                rcvwin = ((u64)msk->rcvq_space.copied << 1) + 16 * advmss;
1824
1825                grow = rcvwin * (msk->rcvq_space.copied - msk->rcvq_space.space);
1826
1827                do_div(grow, msk->rcvq_space.space);
1828                rcvwin += (grow << 1);
1829
1830                rcvmem = SKB_TRUESIZE(advmss + MAX_TCP_HEADER);
1831                while (tcp_win_from_space(sk, rcvmem) < advmss)
1832                        rcvmem += 128;
1833
1834                do_div(rcvwin, advmss);
1835                rcvbuf = min_t(u64, rcvwin * rcvmem,
1836                               sock_net(sk)->ipv4.sysctl_tcp_rmem[2]);
1837
1838                if (rcvbuf > sk->sk_rcvbuf) {
1839                        u32 window_clamp;
1840
1841                        window_clamp = tcp_win_from_space(sk, rcvbuf);
1842                        WRITE_ONCE(sk->sk_rcvbuf, rcvbuf);
1843
1844                        /* Make subflows follow along.  If we do not do this, we
1845                         * get drops at subflow level if skbs can't be moved to
1846                         * the mptcp rx queue fast enough (announced rcv_win can
1847                         * exceed ssk->sk_rcvbuf).
1848                         */
1849                        mptcp_for_each_subflow(msk, subflow) {
1850                                struct sock *ssk;
1851                                bool slow;
1852
1853                                ssk = mptcp_subflow_tcp_sock(subflow);
1854                                slow = lock_sock_fast(ssk);
1855                                WRITE_ONCE(ssk->sk_rcvbuf, rcvbuf);
1856                                tcp_sk(ssk)->window_clamp = window_clamp;
1857                                tcp_cleanup_rbuf(ssk, 1);
1858                                unlock_sock_fast(ssk, slow);
1859                        }
1860                }
1861        }
1862
1863        msk->rcvq_space.space = msk->rcvq_space.copied;
1864new_measure:
1865        msk->rcvq_space.copied = 0;
1866        msk->rcvq_space.time = mstamp;
1867}
1868
1869static void __mptcp_update_rmem(struct sock *sk)
1870{
1871        struct mptcp_sock *msk = mptcp_sk(sk);
1872
1873        if (!msk->rmem_released)
1874                return;
1875
1876        atomic_sub(msk->rmem_released, &sk->sk_rmem_alloc);
1877        sk_mem_uncharge(sk, msk->rmem_released);
1878        WRITE_ONCE(msk->rmem_released, 0);
1879}
1880
1881static void __mptcp_splice_receive_queue(struct sock *sk)
1882{
1883        struct mptcp_sock *msk = mptcp_sk(sk);
1884
1885        skb_queue_splice_tail_init(&sk->sk_receive_queue, &msk->receive_queue);
1886}
1887
1888static bool __mptcp_move_skbs(struct mptcp_sock *msk)
1889{
1890        struct sock *sk = (struct sock *)msk;
1891        unsigned int moved = 0;
1892        bool ret, done;
1893
1894        mptcp_flush_join_list(msk);
1895        do {
1896                struct sock *ssk = mptcp_subflow_recv_lookup(msk);
1897                bool slowpath;
1898
1899                /* we can have data pending in the subflows only if the msk
1900                 * receive buffer was full at subflow_data_ready() time,
1901                 * that is an unlikely slow path.
1902                 */
1903                if (likely(!ssk))
1904                        break;
1905
1906                slowpath = lock_sock_fast(ssk);
1907                mptcp_data_lock(sk);
1908                __mptcp_update_rmem(sk);
1909                done = __mptcp_move_skbs_from_subflow(msk, ssk, &moved);
1910                mptcp_data_unlock(sk);
1911
1912                if (unlikely(ssk->sk_err))
1913                        __mptcp_error_report(sk);
1914                unlock_sock_fast(ssk, slowpath);
1915        } while (!done);
1916
1917        /* acquire the data lock only if some input data is pending */
1918        ret = moved > 0;
1919        if (!RB_EMPTY_ROOT(&msk->out_of_order_queue) ||
1920            !skb_queue_empty_lockless(&sk->sk_receive_queue)) {
1921                mptcp_data_lock(sk);
1922                __mptcp_update_rmem(sk);
1923                ret |= __mptcp_ofo_queue(msk);
1924                __mptcp_splice_receive_queue(sk);
1925                mptcp_data_unlock(sk);
1926        }
1927        if (ret)
1928                mptcp_check_data_fin((struct sock *)msk);
1929        return !skb_queue_empty(&msk->receive_queue);
1930}
1931
1932static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
1933                         int nonblock, int flags, int *addr_len)
1934{
1935        struct mptcp_sock *msk = mptcp_sk(sk);
1936        struct scm_timestamping_internal tss;
1937        int copied = 0, cmsg_flags = 0;
1938        int target;
1939        long timeo;
1940
1941        /* MSG_ERRQUEUE is really a no-op till we support IP_RECVERR */
1942        if (unlikely(flags & MSG_ERRQUEUE))
1943                return inet_recv_error(sk, msg, len, addr_len);
1944
1945        mptcp_lock_sock(sk, __mptcp_splice_receive_queue(sk));
1946        if (unlikely(sk->sk_state == TCP_LISTEN)) {
1947                copied = -ENOTCONN;
1948                goto out_err;
1949        }
1950
1951        timeo = sock_rcvtimeo(sk, nonblock);
1952
1953        len = min_t(size_t, len, INT_MAX);
1954        target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
1955
1956        while (copied < len) {
1957                int bytes_read;
1958
1959                bytes_read = __mptcp_recvmsg_mskq(msk, msg, len - copied, flags, &tss, &cmsg_flags);
1960                if (unlikely(bytes_read < 0)) {
1961                        if (!copied)
1962                                copied = bytes_read;
1963                        goto out_err;
1964                }
1965
1966                copied += bytes_read;
1967
1968                /* be sure to advertise window change */
1969                mptcp_cleanup_rbuf(msk);
1970
1971                if (skb_queue_empty(&msk->receive_queue) && __mptcp_move_skbs(msk))
1972                        continue;
1973
1974                /* only the master socket status is relevant here. The exit
1975                 * conditions mirror closely tcp_recvmsg()
1976                 */
1977                if (copied >= target)
1978                        break;
1979
1980                if (copied) {
1981                        if (sk->sk_err ||
1982                            sk->sk_state == TCP_CLOSE ||
1983                            (sk->sk_shutdown & RCV_SHUTDOWN) ||
1984                            !timeo ||
1985                            signal_pending(current))
1986                                break;
1987                } else {
1988                        if (sk->sk_err) {
1989                                copied = sock_error(sk);
1990                                break;
1991                        }
1992
1993                        if (test_and_clear_bit(MPTCP_WORK_EOF, &msk->flags))
1994                                mptcp_check_for_eof(msk);
1995
1996                        if (sk->sk_shutdown & RCV_SHUTDOWN) {
1997                                /* race breaker: the shutdown could be after the
1998                                 * previous receive queue check
1999                                 */
2000                                if (__mptcp_move_skbs(msk))
2001                                        continue;
2002                                break;
2003                        }
2004
2005                        if (sk->sk_state == TCP_CLOSE) {
2006                                copied = -ENOTCONN;
2007                                break;
2008                        }
2009
2010                        if (!timeo) {
2011                                copied = -EAGAIN;
2012                                break;
2013                        }
2014
2015                        if (signal_pending(current)) {
2016                                copied = sock_intr_errno(timeo);
2017                                break;
2018                        }
2019                }
2020
2021                pr_debug("block timeout %ld", timeo);
2022                mptcp_wait_data(sk, &timeo);
2023        }
2024
2025        if (skb_queue_empty_lockless(&sk->sk_receive_queue) &&
2026            skb_queue_empty(&msk->receive_queue)) {
2027                /* entire backlog drained, clear DATA_READY. */
2028                clear_bit(MPTCP_DATA_READY, &msk->flags);
2029
2030                /* .. race-breaker: ssk might have gotten new data
2031                 * after last __mptcp_move_skbs() returned false.
2032                 */
2033                if (unlikely(__mptcp_move_skbs(msk)))
2034                        set_bit(MPTCP_DATA_READY, &msk->flags);
2035        }
2036
2037out_err:
2038        if (cmsg_flags && copied >= 0) {
2039                if (cmsg_flags & MPTCP_CMSG_TS)
2040                        tcp_recv_timestamp(msg, sk, &tss);
2041        }
2042
2043        pr_debug("msk=%p data_ready=%d rx queue empty=%d copied=%d",
2044                 msk, test_bit(MPTCP_DATA_READY, &msk->flags),
2045                 skb_queue_empty_lockless(&sk->sk_receive_queue), copied);
2046        if (!(flags & MSG_PEEK))
2047                mptcp_rcv_space_adjust(msk, copied);
2048
2049        release_sock(sk);
2050        return copied;
2051}
2052
2053static void mptcp_retransmit_timer(struct timer_list *t)
2054{
2055        struct inet_connection_sock *icsk = from_timer(icsk, t,
2056                                                       icsk_retransmit_timer);
2057        struct sock *sk = &icsk->icsk_inet.sk;
2058        struct mptcp_sock *msk = mptcp_sk(sk);
2059
2060        bh_lock_sock(sk);
2061        if (!sock_owned_by_user(sk)) {
2062                /* we need a process context to retransmit */
2063                if (!test_and_set_bit(MPTCP_WORK_RTX, &msk->flags))
2064                        mptcp_schedule_work(sk);
2065        } else {
2066                /* delegate our work to tcp_release_cb() */
2067                set_bit(MPTCP_RETRANSMIT, &msk->flags);
2068        }
2069        bh_unlock_sock(sk);
2070        sock_put(sk);
2071}
2072
2073static void mptcp_timeout_timer(struct timer_list *t)
2074{
2075        struct sock *sk = from_timer(sk, t, sk_timer);
2076
2077        mptcp_schedule_work(sk);
2078        sock_put(sk);
2079}
2080
2081/* Find an idle subflow.  Return NULL if there is unacked data at tcp
2082 * level.
2083 *
2084 * A backup subflow is returned only if that is the only kind available.
2085 */
2086static struct sock *mptcp_subflow_get_retrans(const struct mptcp_sock *msk)
2087{
2088        struct mptcp_subflow_context *subflow;
2089        struct sock *backup = NULL;
2090
2091        sock_owned_by_me((const struct sock *)msk);
2092
2093        if (__mptcp_check_fallback(msk))
2094                return NULL;
2095
2096        mptcp_for_each_subflow(msk, subflow) {
2097                struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
2098
2099                if (!mptcp_subflow_active(subflow))
2100                        continue;
2101
2102                /* still data outstanding at TCP level?  Don't retransmit. */
2103                if (!tcp_write_queue_empty(ssk)) {
2104                        if (inet_csk(ssk)->icsk_ca_state >= TCP_CA_Loss)
2105                                continue;
2106                        return NULL;
2107                }
2108
2109                if (subflow->backup) {
2110                        if (!backup)
2111                                backup = ssk;
2112                        continue;
2113                }
2114
2115                return ssk;
2116        }
2117
2118        return backup;
2119}
2120
2121static void mptcp_dispose_initial_subflow(struct mptcp_sock *msk)
2122{
2123        if (msk->subflow) {
2124                iput(SOCK_INODE(msk->subflow));
2125                msk->subflow = NULL;
2126        }
2127}
2128
2129/* subflow sockets can be either outgoing (connect) or incoming
2130 * (accept).
2131 *
2132 * Outgoing subflows use in-kernel sockets.
2133 * Incoming subflows do not have their own 'struct socket' allocated,
2134 * so we need to use tcp_close() after detaching them from the mptcp
2135 * parent socket.
2136 */
2137static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
2138                              struct mptcp_subflow_context *subflow)
2139{
2140        struct mptcp_sock *msk = mptcp_sk(sk);
2141
2142        list_del(&subflow->node);
2143
2144        lock_sock_nested(ssk, SINGLE_DEPTH_NESTING);
2145
2146        /* if we are invoked by the msk cleanup code, the subflow is
2147         * already orphaned
2148         */
2149        if (ssk->sk_socket)
2150                sock_orphan(ssk);
2151
2152        subflow->disposable = 1;
2153
2154        /* if ssk hit tcp_done(), tcp_cleanup_ulp() cleared the related ops
2155         * the ssk has been already destroyed, we just need to release the
2156         * reference owned by msk;
2157         */
2158        if (!inet_csk(ssk)->icsk_ulp_ops) {
2159                kfree_rcu(subflow, rcu);
2160        } else {
2161                /* otherwise tcp will dispose of the ssk and subflow ctx */
2162                __tcp_close(ssk, 0);
2163
2164                /* close acquired an extra ref */
2165                __sock_put(ssk);
2166        }
2167        release_sock(ssk);
2168
2169        sock_put(ssk);
2170
2171        if (ssk == msk->last_snd)
2172                msk->last_snd = NULL;
2173
2174        if (ssk == msk->first)
2175                msk->first = NULL;
2176
2177        if (msk->subflow && ssk == msk->subflow->sk)
2178                mptcp_dispose_initial_subflow(msk);
2179}
2180
2181void mptcp_close_ssk(struct sock *sk, struct sock *ssk,
2182                     struct mptcp_subflow_context *subflow)
2183{
2184        if (sk->sk_state == TCP_ESTABLISHED)
2185                mptcp_event(MPTCP_EVENT_SUB_CLOSED, mptcp_sk(sk), ssk, GFP_KERNEL);
2186        __mptcp_close_ssk(sk, ssk, subflow);
2187}
2188
2189static unsigned int mptcp_sync_mss(struct sock *sk, u32 pmtu)
2190{
2191        return 0;
2192}
2193
2194static void __mptcp_close_subflow(struct mptcp_sock *msk)
2195{
2196        struct mptcp_subflow_context *subflow, *tmp;
2197
2198        might_sleep();
2199
2200        list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node) {
2201                struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
2202
2203                if (inet_sk_state_load(ssk) != TCP_CLOSE)
2204                        continue;
2205
2206                /* 'subflow_data_ready' will re-sched once rx queue is empty */
2207                if (!skb_queue_empty_lockless(&ssk->sk_receive_queue))
2208                        continue;
2209
2210                mptcp_close_ssk((struct sock *)msk, ssk, subflow);
2211        }
2212}
2213
2214static bool mptcp_check_close_timeout(const struct sock *sk)
2215{
2216        s32 delta = tcp_jiffies32 - inet_csk(sk)->icsk_mtup.probe_timestamp;
2217        struct mptcp_subflow_context *subflow;
2218
2219        if (delta >= TCP_TIMEWAIT_LEN)
2220                return true;
2221
2222        /* if all subflows are in closed status don't bother with additional
2223         * timeout
2224         */
2225        mptcp_for_each_subflow(mptcp_sk(sk), subflow) {
2226                if (inet_sk_state_load(mptcp_subflow_tcp_sock(subflow)) !=
2227                    TCP_CLOSE)
2228                        return false;
2229        }
2230        return true;
2231}
2232
2233static void mptcp_check_fastclose(struct mptcp_sock *msk)
2234{
2235        struct mptcp_subflow_context *subflow, *tmp;
2236        struct sock *sk = &msk->sk.icsk_inet.sk;
2237
2238        if (likely(!READ_ONCE(msk->rcv_fastclose)))
2239                return;
2240
2241        mptcp_token_destroy(msk);
2242
2243        list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node) {
2244                struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow);
2245                bool slow;
2246
2247                slow = lock_sock_fast(tcp_sk);
2248                if (tcp_sk->sk_state != TCP_CLOSE) {
2249                        tcp_send_active_reset(tcp_sk, GFP_ATOMIC);
2250                        tcp_set_state(tcp_sk, TCP_CLOSE);
2251                }
2252                unlock_sock_fast(tcp_sk, slow);
2253        }
2254
2255        inet_sk_state_store(sk, TCP_CLOSE);
2256        sk->sk_shutdown = SHUTDOWN_MASK;
2257        smp_mb__before_atomic(); /* SHUTDOWN must be visible first */
2258        set_bit(MPTCP_DATA_READY, &msk->flags);
2259        set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags);
2260
2261        mptcp_close_wake_up(sk);
2262}
2263
2264static void __mptcp_retrans(struct sock *sk)
2265{
2266        struct mptcp_sock *msk = mptcp_sk(sk);
2267        struct mptcp_sendmsg_info info = {};
2268        struct mptcp_data_frag *dfrag;
2269        size_t copied = 0;
2270        struct sock *ssk;
2271        int ret;
2272
2273        mptcp_clean_una_wakeup(sk);
2274        dfrag = mptcp_rtx_head(sk);
2275        if (!dfrag) {
2276                if (mptcp_data_fin_enabled(msk)) {
2277                        struct inet_connection_sock *icsk = inet_csk(sk);
2278
2279                        icsk->icsk_retransmits++;
2280                        mptcp_set_datafin_timeout(sk);
2281                        mptcp_send_ack(msk);
2282
2283                        goto reset_timer;
2284                }
2285
2286                return;
2287        }
2288
2289        ssk = mptcp_subflow_get_retrans(msk);
2290        if (!ssk)
2291                goto reset_timer;
2292
2293        lock_sock(ssk);
2294
2295        /* limit retransmission to the bytes already sent on some subflows */
2296        info.sent = 0;
2297        info.limit = READ_ONCE(msk->csum_enabled) ? dfrag->data_len : dfrag->already_sent;
2298        while (info.sent < info.limit) {
2299                if (!mptcp_alloc_tx_skb(sk, ssk))
2300                        break;
2301
2302                ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info);
2303                if (ret <= 0)
2304                        break;
2305
2306                MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_RETRANSSEGS);
2307                copied += ret;
2308                info.sent += ret;
2309        }
2310        if (copied) {
2311                dfrag->already_sent = max(dfrag->already_sent, info.sent);
2312                tcp_push(ssk, 0, info.mss_now, tcp_sk(ssk)->nonagle,
2313                         info.size_goal);
2314        }
2315
2316        mptcp_set_timeout(sk, ssk);
2317        release_sock(ssk);
2318
2319reset_timer:
2320        if (!mptcp_timer_pending(sk))
2321                mptcp_reset_timer(sk);
2322}
2323
2324static void mptcp_worker(struct work_struct *work)
2325{
2326        struct mptcp_sock *msk = container_of(work, struct mptcp_sock, work);
2327        struct sock *sk = &msk->sk.icsk_inet.sk;
2328        int state;
2329
2330        lock_sock(sk);
2331        state = sk->sk_state;
2332        if (unlikely(state == TCP_CLOSE))
2333                goto unlock;
2334
2335        mptcp_check_data_fin_ack(sk);
2336        mptcp_flush_join_list(msk);
2337
2338        mptcp_check_fastclose(msk);
2339
2340        if (msk->pm.status)
2341                mptcp_pm_nl_work(msk);
2342
2343        if (test_and_clear_bit(MPTCP_WORK_EOF, &msk->flags))
2344                mptcp_check_for_eof(msk);
2345
2346        __mptcp_check_send_data_fin(sk);
2347        mptcp_check_data_fin(sk);
2348
2349        /* There is no point in keeping around an orphaned sk timedout or
2350         * closed, but we need the msk around to reply to incoming DATA_FIN,
2351         * even if it is orphaned and in FIN_WAIT2 state
2352         */
2353        if (sock_flag(sk, SOCK_DEAD) &&
2354            (mptcp_check_close_timeout(sk) || sk->sk_state == TCP_CLOSE)) {
2355                inet_sk_state_store(sk, TCP_CLOSE);
2356                __mptcp_destroy_sock(sk);
2357                goto unlock;
2358        }
2359
2360        if (test_and_clear_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))
2361                __mptcp_close_subflow(msk);
2362
2363        if (test_and_clear_bit(MPTCP_WORK_RTX, &msk->flags))
2364                __mptcp_retrans(sk);
2365
2366unlock:
2367        release_sock(sk);
2368        sock_put(sk);
2369}
2370
2371static int __mptcp_init_sock(struct sock *sk)
2372{
2373        struct mptcp_sock *msk = mptcp_sk(sk);
2374
2375        spin_lock_init(&msk->join_list_lock);
2376
2377        INIT_LIST_HEAD(&msk->conn_list);
2378        INIT_LIST_HEAD(&msk->join_list);
2379        INIT_LIST_HEAD(&msk->rtx_queue);
2380        INIT_WORK(&msk->work, mptcp_worker);
2381        __skb_queue_head_init(&msk->receive_queue);
2382        msk->out_of_order_queue = RB_ROOT;
2383        msk->first_pending = NULL;
2384        msk->wmem_reserved = 0;
2385        WRITE_ONCE(msk->rmem_released, 0);
2386        msk->tx_pending_data = 0;
2387
2388        msk->first = NULL;
2389        inet_csk(sk)->icsk_sync_mss = mptcp_sync_mss;
2390        WRITE_ONCE(msk->csum_enabled, mptcp_is_checksum_enabled(sock_net(sk)));
2391
2392        mptcp_pm_data_init(msk);
2393
2394        /* re-use the csk retrans timer for MPTCP-level retrans */
2395        timer_setup(&msk->sk.icsk_retransmit_timer, mptcp_retransmit_timer, 0);
2396        timer_setup(&sk->sk_timer, mptcp_timeout_timer, 0);
2397
2398        return 0;
2399}
2400
2401static int mptcp_init_sock(struct sock *sk)
2402{
2403        struct inet_connection_sock *icsk = inet_csk(sk);
2404        struct net *net = sock_net(sk);
2405        int ret;
2406
2407        ret = __mptcp_init_sock(sk);
2408        if (ret)
2409                return ret;
2410
2411        if (!mptcp_is_enabled(net))
2412                return -ENOPROTOOPT;
2413
2414        if (unlikely(!net->mib.mptcp_statistics) && !mptcp_mib_alloc(net))
2415                return -ENOMEM;
2416
2417        ret = __mptcp_socket_create(mptcp_sk(sk));
2418        if (ret)
2419                return ret;
2420
2421        /* fetch the ca name; do it outside __mptcp_init_sock(), so that clone will
2422         * propagate the correct value
2423         */
2424        tcp_assign_congestion_control(sk);
2425        strcpy(mptcp_sk(sk)->ca_name, icsk->icsk_ca_ops->name);
2426
2427        /* no need to keep a reference to the ops, the name will suffice */
2428        tcp_cleanup_congestion_control(sk);
2429        icsk->icsk_ca_ops = NULL;
2430
2431        sk_sockets_allocated_inc(sk);
2432        sk->sk_rcvbuf = sock_net(sk)->ipv4.sysctl_tcp_rmem[1];
2433        sk->sk_sndbuf = sock_net(sk)->ipv4.sysctl_tcp_wmem[1];
2434
2435        return 0;
2436}
2437
2438static void __mptcp_clear_xmit(struct sock *sk)
2439{
2440        struct mptcp_sock *msk = mptcp_sk(sk);
2441        struct mptcp_data_frag *dtmp, *dfrag;
2442
2443        WRITE_ONCE(msk->first_pending, NULL);
2444        list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list)
2445                dfrag_clear(sk, dfrag);
2446}
2447
2448static void mptcp_cancel_work(struct sock *sk)
2449{
2450        struct mptcp_sock *msk = mptcp_sk(sk);
2451
2452        if (cancel_work_sync(&msk->work))
2453                __sock_put(sk);
2454}
2455
2456void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how)
2457{
2458        lock_sock(ssk);
2459
2460        switch (ssk->sk_state) {
2461        case TCP_LISTEN:
2462                if (!(how & RCV_SHUTDOWN))
2463                        break;
2464                fallthrough;
2465        case TCP_SYN_SENT:
2466                tcp_disconnect(ssk, O_NONBLOCK);
2467                break;
2468        default:
2469                if (__mptcp_check_fallback(mptcp_sk(sk))) {
2470                        pr_debug("Fallback");
2471                        ssk->sk_shutdown |= how;
2472                        tcp_shutdown(ssk, how);
2473                } else {
2474                        pr_debug("Sending DATA_FIN on subflow %p", ssk);
2475                        mptcp_set_timeout(sk, ssk);
2476                        tcp_send_ack(ssk);
2477                        if (!mptcp_timer_pending(sk))
2478                                mptcp_reset_timer(sk);
2479                }
2480                break;
2481        }
2482
2483        release_sock(ssk);
2484}
2485
2486static const unsigned char new_state[16] = {
2487        /* current state:     new state:      action:   */
2488        [0 /* (Invalid) */] = TCP_CLOSE,
2489        [TCP_ESTABLISHED]   = TCP_FIN_WAIT1 | TCP_ACTION_FIN,
2490        [TCP_SYN_SENT]      = TCP_CLOSE,
2491        [TCP_SYN_RECV]      = TCP_FIN_WAIT1 | TCP_ACTION_FIN,
2492        [TCP_FIN_WAIT1]     = TCP_FIN_WAIT1,
2493        [TCP_FIN_WAIT2]     = TCP_FIN_WAIT2,
2494        [TCP_TIME_WAIT]     = TCP_CLOSE,        /* should not happen ! */
2495        [TCP_CLOSE]         = TCP_CLOSE,
2496        [TCP_CLOSE_WAIT]    = TCP_LAST_ACK  | TCP_ACTION_FIN,
2497        [TCP_LAST_ACK]      = TCP_LAST_ACK,
2498        [TCP_LISTEN]        = TCP_CLOSE,
2499        [TCP_CLOSING]       = TCP_CLOSING,
2500        [TCP_NEW_SYN_RECV]  = TCP_CLOSE,        /* should not happen ! */
2501};
2502
2503static int mptcp_close_state(struct sock *sk)
2504{
2505        int next = (int)new_state[sk->sk_state];
2506        int ns = next & TCP_STATE_MASK;
2507
2508        inet_sk_state_store(sk, ns);
2509
2510        return next & TCP_ACTION_FIN;
2511}
2512
2513static void __mptcp_check_send_data_fin(struct sock *sk)
2514{
2515        struct mptcp_subflow_context *subflow;
2516        struct mptcp_sock *msk = mptcp_sk(sk);
2517
2518        pr_debug("msk=%p snd_data_fin_enable=%d pending=%d snd_nxt=%llu write_seq=%llu",
2519                 msk, msk->snd_data_fin_enable, !!mptcp_send_head(sk),
2520                 msk->snd_nxt, msk->write_seq);
2521
2522        /* we still need to enqueue subflows or not really shutting down,
2523         * skip this
2524         */
2525        if (!msk->snd_data_fin_enable || msk->snd_nxt + 1 != msk->write_seq ||
2526            mptcp_send_head(sk))
2527                return;
2528
2529        WRITE_ONCE(msk->snd_nxt, msk->write_seq);
2530
2531        /* fallback socket will not get data_fin/ack, can move to the next
2532         * state now
2533         */
2534        if (__mptcp_check_fallback(msk)) {
2535                if ((1 << sk->sk_state) & (TCPF_CLOSING | TCPF_LAST_ACK)) {
2536                        inet_sk_state_store(sk, TCP_CLOSE);
2537                        mptcp_close_wake_up(sk);
2538                } else if (sk->sk_state == TCP_FIN_WAIT1) {
2539                        inet_sk_state_store(sk, TCP_FIN_WAIT2);
2540                }
2541        }
2542
2543        mptcp_flush_join_list(msk);
2544        mptcp_for_each_subflow(msk, subflow) {
2545                struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow);
2546
2547                mptcp_subflow_shutdown(sk, tcp_sk, SEND_SHUTDOWN);
2548        }
2549}
2550
2551static void __mptcp_wr_shutdown(struct sock *sk)
2552{
2553        struct mptcp_sock *msk = mptcp_sk(sk);
2554
2555        pr_debug("msk=%p snd_data_fin_enable=%d shutdown=%x state=%d pending=%d",
2556                 msk, msk->snd_data_fin_enable, sk->sk_shutdown, sk->sk_state,
2557                 !!mptcp_send_head(sk));
2558
2559        /* will be ignored by fallback sockets */
2560        WRITE_ONCE(msk->write_seq, msk->write_seq + 1);
2561        WRITE_ONCE(msk->snd_data_fin_enable, 1);
2562
2563        __mptcp_check_send_data_fin(sk);
2564}
2565
2566static void __mptcp_destroy_sock(struct sock *sk)
2567{
2568        struct mptcp_subflow_context *subflow, *tmp;
2569        struct mptcp_sock *msk = mptcp_sk(sk);
2570        LIST_HEAD(conn_list);
2571
2572        pr_debug("msk=%p", msk);
2573
2574        might_sleep();
2575
2576        /* be sure to always acquire the join list lock, to sync vs
2577         * mptcp_finish_join().
2578         */
2579        spin_lock_bh(&msk->join_list_lock);
2580        list_splice_tail_init(&msk->join_list, &msk->conn_list);
2581        spin_unlock_bh(&msk->join_list_lock);
2582        list_splice_init(&msk->conn_list, &conn_list);
2583
2584        sk_stop_timer(sk, &msk->sk.icsk_retransmit_timer);
2585        sk_stop_timer(sk, &sk->sk_timer);
2586        msk->pm.status = 0;
2587
2588        list_for_each_entry_safe(subflow, tmp, &conn_list, node) {
2589                struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
2590                __mptcp_close_ssk(sk, ssk, subflow);
2591        }
2592
2593        sk->sk_prot->destroy(sk);
2594
2595        WARN_ON_ONCE(msk->wmem_reserved);
2596        WARN_ON_ONCE(msk->rmem_released);
2597        sk_stream_kill_queues(sk);
2598        xfrm_sk_free_policy(sk);
2599
2600        sk_refcnt_debug_release(sk);
2601        mptcp_dispose_initial_subflow(msk);
2602        sock_put(sk);
2603}
2604
2605static void mptcp_close(struct sock *sk, long timeout)
2606{
2607        struct mptcp_subflow_context *subflow;
2608        bool do_cancel_work = false;
2609
2610        lock_sock(sk);
2611        sk->sk_shutdown = SHUTDOWN_MASK;
2612
2613        if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)) {
2614                inet_sk_state_store(sk, TCP_CLOSE);
2615                goto cleanup;
2616        }
2617
2618        if (mptcp_close_state(sk))
2619                __mptcp_wr_shutdown(sk);
2620
2621        sk_stream_wait_close(sk, timeout);
2622
2623cleanup:
2624        /* orphan all the subflows */
2625        inet_csk(sk)->icsk_mtup.probe_timestamp = tcp_jiffies32;
2626        mptcp_for_each_subflow(mptcp_sk(sk), subflow) {
2627                struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
2628                bool slow = lock_sock_fast(ssk);
2629
2630                sock_orphan(ssk);
2631                unlock_sock_fast(ssk, slow);
2632        }
2633        sock_orphan(sk);
2634
2635        sock_hold(sk);
2636        pr_debug("msk=%p state=%d", sk, sk->sk_state);
2637        if (sk->sk_state == TCP_CLOSE) {
2638                __mptcp_destroy_sock(sk);
2639                do_cancel_work = true;
2640        } else {
2641                sk_reset_timer(sk, &sk->sk_timer, jiffies + TCP_TIMEWAIT_LEN);
2642        }
2643        release_sock(sk);
2644        if (do_cancel_work)
2645                mptcp_cancel_work(sk);
2646
2647        if (mptcp_sk(sk)->token)
2648                mptcp_event(MPTCP_EVENT_CLOSED, mptcp_sk(sk), NULL, GFP_KERNEL);
2649
2650        sock_put(sk);
2651}
2652
2653static void mptcp_copy_inaddrs(struct sock *msk, const struct sock *ssk)
2654{
2655#if IS_ENABLED(CONFIG_MPTCP_IPV6)
2656        const struct ipv6_pinfo *ssk6 = inet6_sk(ssk);
2657        struct ipv6_pinfo *msk6 = inet6_sk(msk);
2658
2659        msk->sk_v6_daddr = ssk->sk_v6_daddr;
2660        msk->sk_v6_rcv_saddr = ssk->sk_v6_rcv_saddr;
2661
2662        if (msk6 && ssk6) {
2663                msk6->saddr = ssk6->saddr;
2664                msk6->flow_label = ssk6->flow_label;
2665        }
2666#endif
2667
2668        inet_sk(msk)->inet_num = inet_sk(ssk)->inet_num;
2669        inet_sk(msk)->inet_dport = inet_sk(ssk)->inet_dport;
2670        inet_sk(msk)->inet_sport = inet_sk(ssk)->inet_sport;
2671        inet_sk(msk)->inet_daddr = inet_sk(ssk)->inet_daddr;
2672        inet_sk(msk)->inet_saddr = inet_sk(ssk)->inet_saddr;
2673        inet_sk(msk)->inet_rcv_saddr = inet_sk(ssk)->inet_rcv_saddr;
2674}
2675
2676static int mptcp_disconnect(struct sock *sk, int flags)
2677{
2678        struct mptcp_subflow_context *subflow;
2679        struct mptcp_sock *msk = mptcp_sk(sk);
2680
2681        mptcp_do_flush_join_list(msk);
2682
2683        mptcp_for_each_subflow(msk, subflow) {
2684                struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
2685
2686                lock_sock(ssk);
2687                tcp_disconnect(ssk, flags);
2688                release_sock(ssk);
2689        }
2690        return 0;
2691}
2692
2693#if IS_ENABLED(CONFIG_MPTCP_IPV6)
2694static struct ipv6_pinfo *mptcp_inet6_sk(const struct sock *sk)
2695{
2696        unsigned int offset = sizeof(struct mptcp6_sock) - sizeof(struct ipv6_pinfo);
2697
2698        return (struct ipv6_pinfo *)(((u8 *)sk) + offset);
2699}
2700#endif
2701
2702struct sock *mptcp_sk_clone(const struct sock *sk,
2703                            const struct mptcp_options_received *mp_opt,
2704                            struct request_sock *req)
2705{
2706        struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
2707        struct sock *nsk = sk_clone_lock(sk, GFP_ATOMIC);
2708        struct mptcp_sock *msk;
2709        u64 ack_seq;
2710
2711        if (!nsk)
2712                return NULL;
2713
2714#if IS_ENABLED(CONFIG_MPTCP_IPV6)
2715        if (nsk->sk_family == AF_INET6)
2716                inet_sk(nsk)->pinet6 = mptcp_inet6_sk(nsk);
2717#endif
2718
2719        __mptcp_init_sock(nsk);
2720
2721        msk = mptcp_sk(nsk);
2722        msk->local_key = subflow_req->local_key;
2723        msk->token = subflow_req->token;
2724        msk->subflow = NULL;
2725        WRITE_ONCE(msk->fully_established, false);
2726        if (mp_opt->csum_reqd)
2727                WRITE_ONCE(msk->csum_enabled, true);
2728
2729        msk->write_seq = subflow_req->idsn + 1;
2730        msk->snd_nxt = msk->write_seq;
2731        msk->snd_una = msk->write_seq;
2732        msk->wnd_end = msk->snd_nxt + req->rsk_rcv_wnd;
2733        msk->setsockopt_seq = mptcp_sk(sk)->setsockopt_seq;
2734
2735        if (mp_opt->mp_capable) {
2736                msk->can_ack = true;
2737                msk->remote_key = mp_opt->sndr_key;
2738                mptcp_crypto_key_sha(msk->remote_key, NULL, &ack_seq);
2739                ack_seq++;
2740                WRITE_ONCE(msk->ack_seq, ack_seq);
2741                WRITE_ONCE(msk->rcv_wnd_sent, ack_seq);
2742        }
2743
2744        sock_reset_flag(nsk, SOCK_RCU_FREE);
2745        /* will be fully established after successful MPC subflow creation */
2746        inet_sk_state_store(nsk, TCP_SYN_RECV);
2747
2748        security_inet_csk_clone(nsk, req);
2749        bh_unlock_sock(nsk);
2750
2751        /* keep a single reference */
2752        __sock_put(nsk);
2753        return nsk;
2754}
2755
2756void mptcp_rcv_space_init(struct mptcp_sock *msk, const struct sock *ssk)
2757{
2758        const struct tcp_sock *tp = tcp_sk(ssk);
2759
2760        msk->rcvq_space.copied = 0;
2761        msk->rcvq_space.rtt_us = 0;
2762
2763        msk->rcvq_space.time = tp->tcp_mstamp;
2764
2765        /* initial rcv_space offering made to peer */
2766        msk->rcvq_space.space = min_t(u32, tp->rcv_wnd,
2767                                      TCP_INIT_CWND * tp->advmss);
2768        if (msk->rcvq_space.space == 0)
2769                msk->rcvq_space.space = TCP_INIT_CWND * TCP_MSS_DEFAULT;
2770
2771        WRITE_ONCE(msk->wnd_end, msk->snd_nxt + tcp_sk(ssk)->snd_wnd);
2772}
2773
2774static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
2775                                 bool kern)
2776{
2777        struct mptcp_sock *msk = mptcp_sk(sk);
2778        struct socket *listener;
2779        struct sock *newsk;
2780
2781        listener = __mptcp_nmpc_socket(msk);
2782        if (WARN_ON_ONCE(!listener)) {
2783                *err = -EINVAL;
2784                return NULL;
2785        }
2786
2787        pr_debug("msk=%p, listener=%p", msk, mptcp_subflow_ctx(listener->sk));
2788        newsk = inet_csk_accept(listener->sk, flags, err, kern);
2789        if (!newsk)
2790                return NULL;
2791
2792        pr_debug("msk=%p, subflow is mptcp=%d", msk, sk_is_mptcp(newsk));
2793        if (sk_is_mptcp(newsk)) {
2794                struct mptcp_subflow_context *subflow;
2795                struct sock *new_mptcp_sock;
2796
2797                subflow = mptcp_subflow_ctx(newsk);
2798                new_mptcp_sock = subflow->conn;
2799
2800                /* is_mptcp should be false if subflow->conn is missing, see
2801                 * subflow_syn_recv_sock()
2802                 */
2803                if (WARN_ON_ONCE(!new_mptcp_sock)) {
2804                        tcp_sk(newsk)->is_mptcp = 0;
2805                        return newsk;
2806                }
2807
2808                /* acquire the 2nd reference for the owning socket */
2809                sock_hold(new_mptcp_sock);
2810                newsk = new_mptcp_sock;
2811                MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEPASSIVEACK);
2812        } else {
2813                MPTCP_INC_STATS(sock_net(sk),
2814                                MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
2815        }
2816
2817        return newsk;
2818}
2819
2820void mptcp_destroy_common(struct mptcp_sock *msk)
2821{
2822        struct sock *sk = (struct sock *)msk;
2823
2824        __mptcp_clear_xmit(sk);
2825
2826        /* move to sk_receive_queue, sk_stream_kill_queues will purge it */
2827        skb_queue_splice_tail_init(&msk->receive_queue, &sk->sk_receive_queue);
2828
2829        skb_rbtree_purge(&msk->out_of_order_queue);
2830        mptcp_token_destroy(msk);
2831        mptcp_pm_free_anno_list(msk);
2832}
2833
2834static void mptcp_destroy(struct sock *sk)
2835{
2836        struct mptcp_sock *msk = mptcp_sk(sk);
2837
2838        mptcp_destroy_common(msk);
2839        sk_sockets_allocated_dec(sk);
2840}
2841
2842void __mptcp_data_acked(struct sock *sk)
2843{
2844        if (!sock_owned_by_user(sk))
2845                __mptcp_clean_una(sk);
2846        else
2847                set_bit(MPTCP_CLEAN_UNA, &mptcp_sk(sk)->flags);
2848
2849        if (mptcp_pending_data_fin_ack(sk))
2850                mptcp_schedule_work(sk);
2851}
2852
2853void __mptcp_check_push(struct sock *sk, struct sock *ssk)
2854{
2855        if (!mptcp_send_head(sk))
2856                return;
2857
2858        if (!sock_owned_by_user(sk)) {
2859                struct sock *xmit_ssk = mptcp_subflow_get_send(mptcp_sk(sk));
2860
2861                if (xmit_ssk == ssk)
2862                        __mptcp_subflow_push_pending(sk, ssk);
2863                else if (xmit_ssk)
2864                        mptcp_subflow_delegate(mptcp_subflow_ctx(xmit_ssk));
2865        } else {
2866                set_bit(MPTCP_PUSH_PENDING, &mptcp_sk(sk)->flags);
2867        }
2868}
2869
2870/* processes deferred events and flush wmem */
2871static void mptcp_release_cb(struct sock *sk)
2872{
2873        for (;;) {
2874                unsigned long flags = 0;
2875
2876                if (test_and_clear_bit(MPTCP_PUSH_PENDING, &mptcp_sk(sk)->flags))
2877                        flags |= BIT(MPTCP_PUSH_PENDING);
2878                if (test_and_clear_bit(MPTCP_RETRANSMIT, &mptcp_sk(sk)->flags))
2879                        flags |= BIT(MPTCP_RETRANSMIT);
2880                if (!flags)
2881                        break;
2882
2883                /* the following actions acquire the subflow socket lock
2884                 *
2885                 * 1) can't be invoked in atomic scope
2886                 * 2) must avoid ABBA deadlock with msk socket spinlock: the RX
2887                 *    datapath acquires the msk socket spinlock while helding
2888                 *    the subflow socket lock
2889                 */
2890
2891                spin_unlock_bh(&sk->sk_lock.slock);
2892                if (flags & BIT(MPTCP_PUSH_PENDING))
2893                        __mptcp_push_pending(sk, 0);
2894                if (flags & BIT(MPTCP_RETRANSMIT))
2895                        __mptcp_retrans(sk);
2896
2897                cond_resched();
2898                spin_lock_bh(&sk->sk_lock.slock);
2899        }
2900
2901        /* be sure to set the current sk state before tacking actions
2902         * depending on sk_state
2903         */
2904        if (test_and_clear_bit(MPTCP_CONNECTED, &mptcp_sk(sk)->flags))
2905                __mptcp_set_connected(sk);
2906        if (test_and_clear_bit(MPTCP_CLEAN_UNA, &mptcp_sk(sk)->flags))
2907                __mptcp_clean_una_wakeup(sk);
2908        if (test_and_clear_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->flags))
2909                __mptcp_error_report(sk);
2910
2911        /* push_pending may touch wmem_reserved, ensure we do the cleanup
2912         * later
2913         */
2914        __mptcp_update_wmem(sk);
2915        __mptcp_update_rmem(sk);
2916}
2917
2918void mptcp_subflow_process_delegated(struct sock *ssk)
2919{
2920        struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
2921        struct sock *sk = subflow->conn;
2922
2923        mptcp_data_lock(sk);
2924        if (!sock_owned_by_user(sk))
2925                __mptcp_subflow_push_pending(sk, ssk);
2926        else
2927                set_bit(MPTCP_PUSH_PENDING, &mptcp_sk(sk)->flags);
2928        mptcp_data_unlock(sk);
2929        mptcp_subflow_delegated_done(subflow);
2930}
2931
2932static int mptcp_hash(struct sock *sk)
2933{
2934        /* should never be called,
2935         * we hash the TCP subflows not the master socket
2936         */
2937        WARN_ON_ONCE(1);
2938        return 0;
2939}
2940
2941static void mptcp_unhash(struct sock *sk)
2942{
2943        /* called from sk_common_release(), but nothing to do here */
2944}
2945
2946static int mptcp_get_port(struct sock *sk, unsigned short snum)
2947{
2948        struct mptcp_sock *msk = mptcp_sk(sk);
2949        struct socket *ssock;
2950
2951        ssock = __mptcp_nmpc_socket(msk);
2952        pr_debug("msk=%p, subflow=%p", msk, ssock);
2953        if (WARN_ON_ONCE(!ssock))
2954                return -EINVAL;
2955
2956        return inet_csk_get_port(ssock->sk, snum);
2957}
2958
2959void mptcp_finish_connect(struct sock *ssk)
2960{
2961        struct mptcp_subflow_context *subflow;
2962        struct mptcp_sock *msk;
2963        struct sock *sk;
2964        u64 ack_seq;
2965
2966        subflow = mptcp_subflow_ctx(ssk);
2967        sk = subflow->conn;
2968        msk = mptcp_sk(sk);
2969
2970        pr_debug("msk=%p, token=%u", sk, subflow->token);
2971
2972        mptcp_crypto_key_sha(subflow->remote_key, NULL, &ack_seq);
2973        ack_seq++;
2974        subflow->map_seq = ack_seq;
2975        subflow->map_subflow_seq = 1;
2976
2977        /* the socket is not connected yet, no msk/subflow ops can access/race
2978         * accessing the field below
2979         */
2980        WRITE_ONCE(msk->remote_key, subflow->remote_key);
2981        WRITE_ONCE(msk->local_key, subflow->local_key);
2982        WRITE_ONCE(msk->write_seq, subflow->idsn + 1);
2983        WRITE_ONCE(msk->snd_nxt, msk->write_seq);
2984        WRITE_ONCE(msk->ack_seq, ack_seq);
2985        WRITE_ONCE(msk->rcv_wnd_sent, ack_seq);
2986        WRITE_ONCE(msk->can_ack, 1);
2987        WRITE_ONCE(msk->snd_una, msk->write_seq);
2988
2989        mptcp_pm_new_connection(msk, ssk, 0);
2990
2991        mptcp_rcv_space_init(msk, ssk);
2992}
2993
2994void mptcp_sock_graft(struct sock *sk, struct socket *parent)
2995{
2996        write_lock_bh(&sk->sk_callback_lock);
2997        rcu_assign_pointer(sk->sk_wq, &parent->wq);
2998        sk_set_socket(sk, parent);
2999        sk->sk_uid = SOCK_INODE(parent)->i_uid;
3000        write_unlock_bh(&sk->sk_callback_lock);
3001}
3002
3003bool mptcp_finish_join(struct sock *ssk)
3004{
3005        struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
3006        struct mptcp_sock *msk = mptcp_sk(subflow->conn);
3007        struct sock *parent = (void *)msk;
3008        struct socket *parent_sock;
3009        bool ret;
3010
3011        pr_debug("msk=%p, subflow=%p", msk, subflow);
3012
3013        /* mptcp socket already closing? */
3014        if (!mptcp_is_fully_established(parent)) {
3015                subflow->reset_reason = MPTCP_RST_EMPTCP;
3016                return false;
3017        }
3018
3019        if (!msk->pm.server_side)
3020                goto out;
3021
3022        if (!mptcp_pm_allow_new_subflow(msk)) {
3023                subflow->reset_reason = MPTCP_RST_EPROHIBIT;
3024                return false;
3025        }
3026
3027        /* active connections are already on conn_list, and we can't acquire
3028         * msk lock here.
3029         * use the join list lock as synchronization point and double-check
3030         * msk status to avoid racing with __mptcp_destroy_sock()
3031         */
3032        spin_lock_bh(&msk->join_list_lock);
3033        ret = inet_sk_state_load(parent) == TCP_ESTABLISHED;
3034        if (ret && !WARN_ON_ONCE(!list_empty(&subflow->node))) {
3035                list_add_tail(&subflow->node, &msk->join_list);
3036                sock_hold(ssk);
3037        }
3038        spin_unlock_bh(&msk->join_list_lock);
3039        if (!ret) {
3040                subflow->reset_reason = MPTCP_RST_EPROHIBIT;
3041                return false;
3042        }
3043
3044        /* attach to msk socket only after we are sure he will deal with us
3045         * at close time
3046         */
3047        parent_sock = READ_ONCE(parent->sk_socket);
3048        if (parent_sock && !ssk->sk_socket)
3049                mptcp_sock_graft(ssk, parent_sock);
3050        subflow->map_seq = READ_ONCE(msk->ack_seq);
3051out:
3052        mptcp_event(MPTCP_EVENT_SUB_ESTABLISHED, msk, ssk, GFP_ATOMIC);
3053        return true;
3054}
3055
3056static void mptcp_shutdown(struct sock *sk, int how)
3057{
3058        pr_debug("sk=%p, how=%d", sk, how);
3059
3060        if ((how & SEND_SHUTDOWN) && mptcp_close_state(sk))
3061                __mptcp_wr_shutdown(sk);
3062}
3063
3064static struct proto mptcp_prot = {
3065        .name           = "MPTCP",
3066        .owner          = THIS_MODULE,
3067        .init           = mptcp_init_sock,
3068        .disconnect     = mptcp_disconnect,
3069        .close          = mptcp_close,
3070        .accept         = mptcp_accept,
3071        .setsockopt     = mptcp_setsockopt,
3072        .getsockopt     = mptcp_getsockopt,
3073        .shutdown       = mptcp_shutdown,
3074        .destroy        = mptcp_destroy,
3075        .sendmsg        = mptcp_sendmsg,
3076        .recvmsg        = mptcp_recvmsg,
3077        .release_cb     = mptcp_release_cb,
3078        .hash           = mptcp_hash,
3079        .unhash         = mptcp_unhash,
3080        .get_port       = mptcp_get_port,
3081        .sockets_allocated      = &mptcp_sockets_allocated,
3082        .memory_allocated       = &tcp_memory_allocated,
3083        .memory_pressure        = &tcp_memory_pressure,
3084        .sysctl_wmem_offset     = offsetof(struct net, ipv4.sysctl_tcp_wmem),
3085        .sysctl_rmem_offset     = offsetof(struct net, ipv4.sysctl_tcp_rmem),
3086        .sysctl_mem     = sysctl_tcp_mem,
3087        .obj_size       = sizeof(struct mptcp_sock),
3088        .slab_flags     = SLAB_TYPESAFE_BY_RCU,
3089        .no_autobind    = true,
3090};
3091
3092static int mptcp_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
3093{
3094        struct mptcp_sock *msk = mptcp_sk(sock->sk);
3095        struct socket *ssock;
3096        int err;
3097
3098        lock_sock(sock->sk);
3099        ssock = __mptcp_nmpc_socket(msk);
3100        if (!ssock) {
3101                err = -EINVAL;
3102                goto unlock;
3103        }
3104
3105        err = ssock->ops->bind(ssock, uaddr, addr_len);
3106        if (!err)
3107                mptcp_copy_inaddrs(sock->sk, ssock->sk);
3108
3109unlock:
3110        release_sock(sock->sk);
3111        return err;
3112}
3113
3114static void mptcp_subflow_early_fallback(struct mptcp_sock *msk,
3115                                         struct mptcp_subflow_context *subflow)
3116{
3117        subflow->request_mptcp = 0;
3118        __mptcp_do_fallback(msk);
3119}
3120
3121static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr,
3122                                int addr_len, int flags)
3123{
3124        struct mptcp_sock *msk = mptcp_sk(sock->sk);
3125        struct mptcp_subflow_context *subflow;
3126        struct socket *ssock;
3127        int err;
3128
3129        lock_sock(sock->sk);
3130        if (sock->state != SS_UNCONNECTED && msk->subflow) {
3131                /* pending connection or invalid state, let existing subflow
3132                 * cope with that
3133                 */
3134                ssock = msk->subflow;
3135                goto do_connect;
3136        }
3137
3138        ssock = __mptcp_nmpc_socket(msk);
3139        if (!ssock) {
3140                err = -EINVAL;
3141                goto unlock;
3142        }
3143
3144        mptcp_token_destroy(msk);
3145        inet_sk_state_store(sock->sk, TCP_SYN_SENT);
3146        subflow = mptcp_subflow_ctx(ssock->sk);
3147#ifdef CONFIG_TCP_MD5SIG
3148        /* no MPTCP if MD5SIG is enabled on this socket or we may run out of
3149         * TCP option space.
3150         */
3151        if (rcu_access_pointer(tcp_sk(ssock->sk)->md5sig_info))
3152                mptcp_subflow_early_fallback(msk, subflow);
3153#endif
3154        if (subflow->request_mptcp && mptcp_token_new_connect(ssock->sk)) {
3155                MPTCP_INC_STATS(sock_net(ssock->sk), MPTCP_MIB_TOKENFALLBACKINIT);
3156                mptcp_subflow_early_fallback(msk, subflow);
3157        }
3158        if (likely(!__mptcp_check_fallback(msk)))
3159                MPTCP_INC_STATS(sock_net(sock->sk), MPTCP_MIB_MPCAPABLEACTIVE);
3160
3161do_connect:
3162        err = ssock->ops->connect(ssock, uaddr, addr_len, flags);
3163        sock->state = ssock->state;
3164
3165        /* on successful connect, the msk state will be moved to established by
3166         * subflow_finish_connect()
3167         */
3168        if (!err || err == -EINPROGRESS)
3169                mptcp_copy_inaddrs(sock->sk, ssock->sk);
3170        else
3171                inet_sk_state_store(sock->sk, inet_sk_state_load(ssock->sk));
3172
3173unlock:
3174        release_sock(sock->sk);
3175        return err;
3176}
3177
3178static int mptcp_listen(struct socket *sock, int backlog)
3179{
3180        struct mptcp_sock *msk = mptcp_sk(sock->sk);
3181        struct socket *ssock;
3182        int err;
3183
3184        pr_debug("msk=%p", msk);
3185
3186        lock_sock(sock->sk);
3187        ssock = __mptcp_nmpc_socket(msk);
3188        if (!ssock) {
3189                err = -EINVAL;
3190                goto unlock;
3191        }
3192
3193        mptcp_token_destroy(msk);
3194        inet_sk_state_store(sock->sk, TCP_LISTEN);
3195        sock_set_flag(sock->sk, SOCK_RCU_FREE);
3196
3197        err = ssock->ops->listen(ssock, backlog);
3198        inet_sk_state_store(sock->sk, inet_sk_state_load(ssock->sk));
3199        if (!err)
3200                mptcp_copy_inaddrs(sock->sk, ssock->sk);
3201
3202unlock:
3203        release_sock(sock->sk);
3204        return err;
3205}
3206
3207static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
3208                               int flags, bool kern)
3209{
3210        struct mptcp_sock *msk = mptcp_sk(sock->sk);
3211        struct socket *ssock;
3212        int err;
3213
3214        pr_debug("msk=%p", msk);
3215
3216        lock_sock(sock->sk);
3217        if (sock->sk->sk_state != TCP_LISTEN)
3218                goto unlock_fail;
3219
3220        ssock = __mptcp_nmpc_socket(msk);
3221        if (!ssock)
3222                goto unlock_fail;
3223
3224        clear_bit(MPTCP_DATA_READY, &msk->flags);
3225        sock_hold(ssock->sk);
3226        release_sock(sock->sk);
3227
3228        err = ssock->ops->accept(sock, newsock, flags, kern);
3229        if (err == 0 && !mptcp_is_tcpsk(newsock->sk)) {
3230                struct mptcp_sock *msk = mptcp_sk(newsock->sk);
3231                struct mptcp_subflow_context *subflow;
3232                struct sock *newsk = newsock->sk;
3233
3234                lock_sock(newsk);
3235
3236                /* PM/worker can now acquire the first subflow socket
3237                 * lock without racing with listener queue cleanup,
3238                 * we can notify it, if needed.
3239                 *
3240                 * Even if remote has reset the initial subflow by now
3241                 * the refcnt is still at least one.
3242                 */
3243                subflow = mptcp_subflow_ctx(msk->first);
3244                list_add(&subflow->node, &msk->conn_list);
3245                sock_hold(msk->first);
3246                if (mptcp_is_fully_established(newsk))
3247                        mptcp_pm_fully_established(msk, msk->first, GFP_KERNEL);
3248
3249                mptcp_copy_inaddrs(newsk, msk->first);
3250                mptcp_rcv_space_init(msk, msk->first);
3251                mptcp_propagate_sndbuf(newsk, msk->first);
3252
3253                /* set ssk->sk_socket of accept()ed flows to mptcp socket.
3254                 * This is needed so NOSPACE flag can be set from tcp stack.
3255                 */
3256                mptcp_flush_join_list(msk);
3257                mptcp_for_each_subflow(msk, subflow) {
3258                        struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
3259
3260                        if (!ssk->sk_socket)
3261                                mptcp_sock_graft(ssk, newsock);
3262                }
3263                release_sock(newsk);
3264        }
3265
3266        if (inet_csk_listen_poll(ssock->sk))
3267                set_bit(MPTCP_DATA_READY, &msk->flags);
3268        sock_put(ssock->sk);
3269        return err;
3270
3271unlock_fail:
3272        release_sock(sock->sk);
3273        return -EINVAL;
3274}
3275
3276static __poll_t mptcp_check_readable(struct mptcp_sock *msk)
3277{
3278        return test_bit(MPTCP_DATA_READY, &msk->flags) ? EPOLLIN | EPOLLRDNORM :
3279               0;
3280}
3281
3282static __poll_t mptcp_check_writeable(struct mptcp_sock *msk)
3283{
3284        struct sock *sk = (struct sock *)msk;
3285
3286        if (unlikely(sk->sk_shutdown & SEND_SHUTDOWN))
3287                return EPOLLOUT | EPOLLWRNORM;
3288
3289        if (sk_stream_is_writeable(sk))
3290                return EPOLLOUT | EPOLLWRNORM;
3291
3292        mptcp_set_nospace(sk);
3293        smp_mb__after_atomic(); /* msk->flags is changed by write_space cb */
3294        if (sk_stream_is_writeable(sk))
3295                return EPOLLOUT | EPOLLWRNORM;
3296
3297        return 0;
3298}
3299
3300static __poll_t mptcp_poll(struct file *file, struct socket *sock,
3301                           struct poll_table_struct *wait)
3302{
3303        struct sock *sk = sock->sk;
3304        struct mptcp_sock *msk;
3305        __poll_t mask = 0;
3306        int state;
3307
3308        msk = mptcp_sk(sk);
3309        sock_poll_wait(file, sock, wait);
3310
3311        state = inet_sk_state_load(sk);
3312        pr_debug("msk=%p state=%d flags=%lx", msk, state, msk->flags);
3313        if (state == TCP_LISTEN)
3314                return mptcp_check_readable(msk);
3315
3316        if (state != TCP_SYN_SENT && state != TCP_SYN_RECV) {
3317                mask |= mptcp_check_readable(msk);
3318                mask |= mptcp_check_writeable(msk);
3319        }
3320        if (sk->sk_shutdown == SHUTDOWN_MASK || state == TCP_CLOSE)
3321                mask |= EPOLLHUP;
3322        if (sk->sk_shutdown & RCV_SHUTDOWN)
3323                mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;
3324
3325        /* This barrier is coupled with smp_wmb() in tcp_reset() */
3326        smp_rmb();
3327        if (sk->sk_err)
3328                mask |= EPOLLERR;
3329
3330        return mask;
3331}
3332
3333static const struct proto_ops mptcp_stream_ops = {
3334        .family            = PF_INET,
3335        .owner             = THIS_MODULE,
3336        .release           = inet_release,
3337        .bind              = mptcp_bind,
3338        .connect           = mptcp_stream_connect,
3339        .socketpair        = sock_no_socketpair,
3340        .accept            = mptcp_stream_accept,
3341        .getname           = inet_getname,
3342        .poll              = mptcp_poll,
3343        .ioctl             = inet_ioctl,
3344        .gettstamp         = sock_gettstamp,
3345        .listen            = mptcp_listen,
3346        .shutdown          = inet_shutdown,
3347        .setsockopt        = sock_common_setsockopt,
3348        .getsockopt        = sock_common_getsockopt,
3349        .sendmsg           = inet_sendmsg,
3350        .recvmsg           = inet_recvmsg,
3351        .mmap              = sock_no_mmap,
3352        .sendpage          = inet_sendpage,
3353};
3354
3355static struct inet_protosw mptcp_protosw = {
3356        .type           = SOCK_STREAM,
3357        .protocol       = IPPROTO_MPTCP,
3358        .prot           = &mptcp_prot,
3359        .ops            = &mptcp_stream_ops,
3360        .flags          = INET_PROTOSW_ICSK,
3361};
3362
3363static int mptcp_napi_poll(struct napi_struct *napi, int budget)
3364{
3365        struct mptcp_delegated_action *delegated;
3366        struct mptcp_subflow_context *subflow;
3367        int work_done = 0;
3368
3369        delegated = container_of(napi, struct mptcp_delegated_action, napi);
3370        while ((subflow = mptcp_subflow_delegated_next(delegated)) != NULL) {
3371                struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
3372
3373                bh_lock_sock_nested(ssk);
3374                if (!sock_owned_by_user(ssk) &&
3375                    mptcp_subflow_has_delegated_action(subflow))
3376                        mptcp_subflow_process_delegated(ssk);
3377                /* ... elsewhere tcp_release_cb_override already processed
3378                 * the action or will do at next release_sock().
3379                 * In both case must dequeue the subflow here - on the same
3380                 * CPU that scheduled it.
3381                 */
3382                bh_unlock_sock(ssk);
3383                sock_put(ssk);
3384
3385                if (++work_done == budget)
3386                        return budget;
3387        }
3388
3389        /* always provide a 0 'work_done' argument, so that napi_complete_done
3390         * will not try accessing the NULL napi->dev ptr
3391         */
3392        napi_complete_done(napi, 0);
3393        return work_done;
3394}
3395
3396void __init mptcp_proto_init(void)
3397{
3398        struct mptcp_delegated_action *delegated;
3399        int cpu;
3400
3401        mptcp_prot.h.hashinfo = tcp_prot.h.hashinfo;
3402
3403        if (percpu_counter_init(&mptcp_sockets_allocated, 0, GFP_KERNEL))
3404                panic("Failed to allocate MPTCP pcpu counter\n");
3405
3406        init_dummy_netdev(&mptcp_napi_dev);
3407        for_each_possible_cpu(cpu) {
3408                delegated = per_cpu_ptr(&mptcp_delegated_actions, cpu);
3409                INIT_LIST_HEAD(&delegated->head);
3410                netif_tx_napi_add(&mptcp_napi_dev, &delegated->napi, mptcp_napi_poll,
3411                                  NAPI_POLL_WEIGHT);
3412                napi_enable(&delegated->napi);
3413        }
3414
3415        mptcp_subflow_init();
3416        mptcp_pm_init();
3417        mptcp_token_init();
3418
3419        if (proto_register(&mptcp_prot, 1) != 0)
3420                panic("Failed to register MPTCP proto.\n");
3421
3422        inet_register_protosw(&mptcp_protosw);
3423
3424        BUILD_BUG_ON(sizeof(struct mptcp_skb_cb) > sizeof_field(struct sk_buff, cb));
3425}
3426
3427#if IS_ENABLED(CONFIG_MPTCP_IPV6)
3428static const struct proto_ops mptcp_v6_stream_ops = {
3429        .family            = PF_INET6,
3430        .owner             = THIS_MODULE,
3431        .release           = inet6_release,
3432        .bind              = mptcp_bind,
3433        .connect           = mptcp_stream_connect,
3434        .socketpair        = sock_no_socketpair,
3435        .accept            = mptcp_stream_accept,
3436        .getname           = inet6_getname,
3437        .poll              = mptcp_poll,
3438        .ioctl             = inet6_ioctl,
3439        .gettstamp         = sock_gettstamp,
3440        .listen            = mptcp_listen,
3441        .shutdown          = inet_shutdown,
3442        .setsockopt        = sock_common_setsockopt,
3443        .getsockopt        = sock_common_getsockopt,
3444        .sendmsg           = inet6_sendmsg,
3445        .recvmsg           = inet6_recvmsg,
3446        .mmap              = sock_no_mmap,
3447        .sendpage          = inet_sendpage,
3448#ifdef CONFIG_COMPAT
3449        .compat_ioctl      = inet6_compat_ioctl,
3450#endif
3451};
3452
3453static struct proto mptcp_v6_prot;
3454
3455static void mptcp_v6_destroy(struct sock *sk)
3456{
3457        mptcp_destroy(sk);
3458        inet6_destroy_sock(sk);
3459}
3460
3461static struct inet_protosw mptcp_v6_protosw = {
3462        .type           = SOCK_STREAM,
3463        .protocol       = IPPROTO_MPTCP,
3464        .prot           = &mptcp_v6_prot,
3465        .ops            = &mptcp_v6_stream_ops,
3466        .flags          = INET_PROTOSW_ICSK,
3467};
3468
3469int __init mptcp_proto_v6_init(void)
3470{
3471        int err;
3472
3473        mptcp_v6_prot = mptcp_prot;
3474        strcpy(mptcp_v6_prot.name, "MPTCPv6");
3475        mptcp_v6_prot.slab = NULL;
3476        mptcp_v6_prot.destroy = mptcp_v6_destroy;
3477        mptcp_v6_prot.obj_size = sizeof(struct mptcp6_sock);
3478
3479        err = proto_register(&mptcp_v6_prot, 1);
3480        if (err)
3481                return err;
3482
3483        err = inet6_register_protosw(&mptcp_v6_protosw);
3484        if (err)
3485                proto_unregister(&mptcp_v6_prot);
3486
3487        return err;
3488}
3489#endif
3490
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