linux/include/net/netlink.h
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   1#ifndef __NET_NETLINK_H
   2#define __NET_NETLINK_H
   3
   4#include <linux/types.h>
   5#include <linux/netlink.h>
   6#include <linux/jiffies.h>
   7
   8/* ========================================================================
   9 *         Netlink Messages and Attributes Interface (As Seen On TV)
  10 * ------------------------------------------------------------------------
  11 *                          Messages Interface
  12 * ------------------------------------------------------------------------
  13 *
  14 * Message Format:
  15 *    <--- nlmsg_total_size(payload)  --->
  16 *    <-- nlmsg_msg_size(payload) ->
  17 *   +----------+- - -+-------------+- - -+-------- - -
  18 *   | nlmsghdr | Pad |   Payload   | Pad | nlmsghdr
  19 *   +----------+- - -+-------------+- - -+-------- - -
  20 *   nlmsg_data(nlh)---^                   ^
  21 *   nlmsg_next(nlh)-----------------------+
  22 *
  23 * Payload Format:
  24 *    <---------------------- nlmsg_len(nlh) --------------------->
  25 *    <------ hdrlen ------>       <- nlmsg_attrlen(nlh, hdrlen) ->
  26 *   +----------------------+- - -+--------------------------------+
  27 *   |     Family Header    | Pad |           Attributes           |
  28 *   +----------------------+- - -+--------------------------------+
  29 *   nlmsg_attrdata(nlh, hdrlen)---^
  30 *
  31 * Data Structures:
  32 *   struct nlmsghdr                    netlink message header
  33 *
  34 * Message Construction:
  35 *   nlmsg_new()                        create a new netlink message
  36 *   nlmsg_put()                        add a netlink message to an skb
  37 *   nlmsg_put_answer()                 callback based nlmsg_put()
  38 *   nlmsg_end()                        finalize netlink message
  39 *   nlmsg_get_pos()                    return current position in message
  40 *   nlmsg_trim()                       trim part of message
  41 *   nlmsg_cancel()                     cancel message construction
  42 *   nlmsg_free()                       free a netlink message
  43 *
  44 * Message Sending:
  45 *   nlmsg_multicast()                  multicast message to several groups
  46 *   nlmsg_unicast()                    unicast a message to a single socket
  47 *   nlmsg_notify()                     send notification message
  48 *
  49 * Message Length Calculations:
  50 *   nlmsg_msg_size(payload)            length of message w/o padding
  51 *   nlmsg_total_size(payload)          length of message w/ padding
  52 *   nlmsg_padlen(payload)              length of padding at tail
  53 *
  54 * Message Payload Access:
  55 *   nlmsg_data(nlh)                    head of message payload
  56 *   nlmsg_len(nlh)                     length of message payload
  57 *   nlmsg_attrdata(nlh, hdrlen)        head of attributes data
  58 *   nlmsg_attrlen(nlh, hdrlen)         length of attributes data
  59 *
  60 * Message Parsing:
  61 *   nlmsg_ok(nlh, remaining)           does nlh fit into remaining bytes?
  62 *   nlmsg_next(nlh, remaining)         get next netlink message
  63 *   nlmsg_parse()                      parse attributes of a message
  64 *   nlmsg_find_attr()                  find an attribute in a message
  65 *   nlmsg_for_each_msg()               loop over all messages
  66 *   nlmsg_validate()                   validate netlink message incl. attrs
  67 *   nlmsg_for_each_attr()              loop over all attributes
  68 *
  69 * Misc:
  70 *   nlmsg_report()                     report back to application?
  71 *
  72 * ------------------------------------------------------------------------
  73 *                          Attributes Interface
  74 * ------------------------------------------------------------------------
  75 *
  76 * Attribute Format:
  77 *    <------- nla_total_size(payload) ------->
  78 *    <---- nla_attr_size(payload) ----->
  79 *   +----------+- - -+- - - - - - - - - +- - -+-------- - -
  80 *   |  Header  | Pad |     Payload      | Pad |  Header
  81 *   +----------+- - -+- - - - - - - - - +- - -+-------- - -
  82 *                     <- nla_len(nla) ->      ^
  83 *   nla_data(nla)----^                        |
  84 *   nla_next(nla)-----------------------------'
  85 *
  86 * Data Structures:
  87 *   struct nlattr                      netlink attribute header
  88 *
  89 * Attribute Construction:
  90 *   nla_reserve(skb, type, len)        reserve room for an attribute
  91 *   nla_reserve_nohdr(skb, len)        reserve room for an attribute w/o hdr
  92 *   nla_put(skb, type, len, data)      add attribute to skb
  93 *   nla_put_nohdr(skb, len, data)      add attribute w/o hdr
  94 *   nla_append(skb, len, data)         append data to skb
  95 *
  96 * Attribute Construction for Basic Types:
  97 *   nla_put_u8(skb, type, value)       add u8 attribute to skb
  98 *   nla_put_u16(skb, type, value)      add u16 attribute to skb
  99 *   nla_put_u32(skb, type, value)      add u32 attribute to skb
 100 *   nla_put_u64(skb, type, value)      add u64 attribute to skb
 101 *   nla_put_string(skb, type, str)     add string attribute to skb
 102 *   nla_put_flag(skb, type)            add flag attribute to skb
 103 *   nla_put_msecs(skb, type, jiffies)  add msecs attribute to skb
 104 *
 105 * Nested Attributes Construction:
 106 *   nla_nest_start(skb, type)          start a nested attribute
 107 *   nla_nest_end(skb, nla)             finalize a nested attribute
 108 *   nla_nest_cancel(skb, nla)          cancel nested attribute construction
 109 *
 110 * Attribute Length Calculations:
 111 *   nla_attr_size(payload)             length of attribute w/o padding
 112 *   nla_total_size(payload)            length of attribute w/ padding
 113 *   nla_padlen(payload)                length of padding
 114 *
 115 * Attribute Payload Access:
 116 *   nla_data(nla)                      head of attribute payload
 117 *   nla_len(nla)                       length of attribute payload
 118 *
 119 * Attribute Payload Access for Basic Types:
 120 *   nla_get_u8(nla)                    get payload for a u8 attribute
 121 *   nla_get_u16(nla)                   get payload for a u16 attribute
 122 *   nla_get_u32(nla)                   get payload for a u32 attribute
 123 *   nla_get_u64(nla)                   get payload for a u64 attribute
 124 *   nla_get_flag(nla)                  return 1 if flag is true
 125 *   nla_get_msecs(nla)                 get payload for a msecs attribute
 126 *
 127 * Attribute Misc:
 128 *   nla_memcpy(dest, nla, count)       copy attribute into memory
 129 *   nla_memcmp(nla, data, size)        compare attribute with memory area
 130 *   nla_strlcpy(dst, nla, size)        copy attribute to a sized string
 131 *   nla_strcmp(nla, str)               compare attribute with string
 132 *
 133 * Attribute Parsing:
 134 *   nla_ok(nla, remaining)             does nla fit into remaining bytes?
 135 *   nla_next(nla, remaining)           get next netlink attribute
 136 *   nla_validate()                     validate a stream of attributes
 137 *   nla_validate_nested()              validate a stream of nested attributes
 138 *   nla_find()                         find attribute in stream of attributes
 139 *   nla_find_nested()                  find attribute in nested attributes
 140 *   nla_parse()                        parse and validate stream of attrs
 141 *   nla_parse_nested()                 parse nested attribuets
 142 *   nla_for_each_attr()                loop over all attributes
 143 *   nla_for_each_nested()              loop over the nested attributes
 144 *=========================================================================
 145 */
 146
 147 /**
 148  * Standard attribute types to specify validation policy
 149  */
 150enum {
 151        NLA_UNSPEC,
 152        NLA_U8,
 153        NLA_U16,
 154        NLA_U32,
 155        NLA_U64,
 156        NLA_STRING,
 157        NLA_FLAG,
 158        NLA_MSECS,
 159        NLA_NESTED,
 160        NLA_NESTED_COMPAT,
 161        NLA_NUL_STRING,
 162        NLA_BINARY,
 163        __NLA_TYPE_MAX,
 164};
 165
 166#define NLA_TYPE_MAX (__NLA_TYPE_MAX - 1)
 167
 168/**
 169 * struct nla_policy - attribute validation policy
 170 * @type: Type of attribute or NLA_UNSPEC
 171 * @len: Type specific length of payload
 172 *
 173 * Policies are defined as arrays of this struct, the array must be
 174 * accessible by attribute type up to the highest identifier to be expected.
 175 *
 176 * Meaning of `len' field:
 177 *    NLA_STRING           Maximum length of string
 178 *    NLA_NUL_STRING       Maximum length of string (excluding NUL)
 179 *    NLA_FLAG             Unused
 180 *    NLA_BINARY           Maximum length of attribute payload
 181 *    NLA_NESTED           Don't use `len' field -- length verification is
 182 *                         done by checking len of nested header (or empty)
 183 *    NLA_NESTED_COMPAT    Minimum length of structure payload
 184 *    NLA_U8, NLA_U16,
 185 *    NLA_U32, NLA_U64,
 186 *    NLA_MSECS            Leaving the length field zero will verify the
 187 *                         given type fits, using it verifies minimum length
 188 *                         just like "All other"
 189 *    All other            Minimum length of attribute payload
 190 *
 191 * Example:
 192 * static const struct nla_policy my_policy[ATTR_MAX+1] = {
 193 *      [ATTR_FOO] = { .type = NLA_U16 },
 194 *      [ATTR_BAR] = { .type = NLA_STRING, .len = BARSIZ },
 195 *      [ATTR_BAZ] = { .len = sizeof(struct mystruct) },
 196 * };
 197 */
 198struct nla_policy {
 199        u16             type;
 200        u16             len;
 201};
 202
 203/**
 204 * struct nl_info - netlink source information
 205 * @nlh: Netlink message header of original request
 206 * @pid: Netlink PID of requesting application
 207 */
 208struct nl_info {
 209        struct nlmsghdr         *nlh;
 210        struct net              *nl_net;
 211        u32                     pid;
 212};
 213
 214extern int              netlink_rcv_skb(struct sk_buff *skb,
 215                                        int (*cb)(struct sk_buff *,
 216                                                  struct nlmsghdr *));
 217extern int              nlmsg_notify(struct sock *sk, struct sk_buff *skb,
 218                                     u32 pid, unsigned int group, int report,
 219                                     gfp_t flags);
 220
 221extern int              nla_validate(const struct nlattr *head,
 222                                     int len, int maxtype,
 223                                     const struct nla_policy *policy);
 224extern int              nla_parse(struct nlattr **tb, int maxtype,
 225                                  const struct nlattr *head, int len,
 226                                  const struct nla_policy *policy);
 227extern int              nla_policy_len(const struct nla_policy *, int);
 228extern struct nlattr *  nla_find(const struct nlattr *head,
 229                                 int len, int attrtype);
 230extern size_t           nla_strlcpy(char *dst, const struct nlattr *nla,
 231                                    size_t dstsize);
 232extern int              nla_memcpy(void *dest, const struct nlattr *src, int count);
 233extern int              nla_memcmp(const struct nlattr *nla, const void *data,
 234                                   size_t size);
 235extern int              nla_strcmp(const struct nlattr *nla, const char *str);
 236extern struct nlattr *  __nla_reserve(struct sk_buff *skb, int attrtype,
 237                                      int attrlen);
 238extern void *           __nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
 239extern struct nlattr *  nla_reserve(struct sk_buff *skb, int attrtype,
 240                                    int attrlen);
 241extern void *           nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
 242extern void             __nla_put(struct sk_buff *skb, int attrtype,
 243                                  int attrlen, const void *data);
 244extern void             __nla_put_nohdr(struct sk_buff *skb, int attrlen,
 245                                        const void *data);
 246extern int              nla_put(struct sk_buff *skb, int attrtype,
 247                                int attrlen, const void *data);
 248extern int              nla_put_nohdr(struct sk_buff *skb, int attrlen,
 249                                      const void *data);
 250extern int              nla_append(struct sk_buff *skb, int attrlen,
 251                                   const void *data);
 252
 253/**************************************************************************
 254 * Netlink Messages
 255 **************************************************************************/
 256
 257/**
 258 * nlmsg_msg_size - length of netlink message not including padding
 259 * @payload: length of message payload
 260 */
 261static inline int nlmsg_msg_size(int payload)
 262{
 263        return NLMSG_HDRLEN + payload;
 264}
 265
 266/**
 267 * nlmsg_total_size - length of netlink message including padding
 268 * @payload: length of message payload
 269 */
 270static inline int nlmsg_total_size(int payload)
 271{
 272        return NLMSG_ALIGN(nlmsg_msg_size(payload));
 273}
 274
 275/**
 276 * nlmsg_padlen - length of padding at the message's tail
 277 * @payload: length of message payload
 278 */
 279static inline int nlmsg_padlen(int payload)
 280{
 281        return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
 282}
 283
 284/**
 285 * nlmsg_data - head of message payload
 286 * @nlh: netlink message header
 287 */
 288static inline void *nlmsg_data(const struct nlmsghdr *nlh)
 289{
 290        return (unsigned char *) nlh + NLMSG_HDRLEN;
 291}
 292
 293/**
 294 * nlmsg_len - length of message payload
 295 * @nlh: netlink message header
 296 */
 297static inline int nlmsg_len(const struct nlmsghdr *nlh)
 298{
 299        return nlh->nlmsg_len - NLMSG_HDRLEN;
 300}
 301
 302/**
 303 * nlmsg_attrdata - head of attributes data
 304 * @nlh: netlink message header
 305 * @hdrlen: length of family specific header
 306 */
 307static inline struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh,
 308                                            int hdrlen)
 309{
 310        unsigned char *data = nlmsg_data(nlh);
 311        return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
 312}
 313
 314/**
 315 * nlmsg_attrlen - length of attributes data
 316 * @nlh: netlink message header
 317 * @hdrlen: length of family specific header
 318 */
 319static inline int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
 320{
 321        return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);
 322}
 323
 324/**
 325 * nlmsg_ok - check if the netlink message fits into the remaining bytes
 326 * @nlh: netlink message header
 327 * @remaining: number of bytes remaining in message stream
 328 */
 329static inline int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
 330{
 331        return (remaining >= (int) sizeof(struct nlmsghdr) &&
 332                nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
 333                nlh->nlmsg_len <= remaining);
 334}
 335
 336/**
 337 * nlmsg_next - next netlink message in message stream
 338 * @nlh: netlink message header
 339 * @remaining: number of bytes remaining in message stream
 340 *
 341 * Returns the next netlink message in the message stream and
 342 * decrements remaining by the size of the current message.
 343 */
 344static inline struct nlmsghdr *
 345nlmsg_next(const struct nlmsghdr *nlh, int *remaining)
 346{
 347        int totlen = NLMSG_ALIGN(nlh->nlmsg_len);
 348
 349        *remaining -= totlen;
 350
 351        return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
 352}
 353
 354/**
 355 * nlmsg_parse - parse attributes of a netlink message
 356 * @nlh: netlink message header
 357 * @hdrlen: length of family specific header
 358 * @tb: destination array with maxtype+1 elements
 359 * @maxtype: maximum attribute type to be expected
 360 * @policy: validation policy
 361 *
 362 * See nla_parse()
 363 */
 364static inline int nlmsg_parse(const struct nlmsghdr *nlh, int hdrlen,
 365                              struct nlattr *tb[], int maxtype,
 366                              const struct nla_policy *policy)
 367{
 368        if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 369                return -EINVAL;
 370
 371        return nla_parse(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
 372                         nlmsg_attrlen(nlh, hdrlen), policy);
 373}
 374
 375/**
 376 * nlmsg_find_attr - find a specific attribute in a netlink message
 377 * @nlh: netlink message header
 378 * @hdrlen: length of familiy specific header
 379 * @attrtype: type of attribute to look for
 380 *
 381 * Returns the first attribute which matches the specified type.
 382 */
 383static inline struct nlattr *nlmsg_find_attr(const struct nlmsghdr *nlh,
 384                                             int hdrlen, int attrtype)
 385{
 386        return nla_find(nlmsg_attrdata(nlh, hdrlen),
 387                        nlmsg_attrlen(nlh, hdrlen), attrtype);
 388}
 389
 390/**
 391 * nlmsg_validate - validate a netlink message including attributes
 392 * @nlh: netlinket message header
 393 * @hdrlen: length of familiy specific header
 394 * @maxtype: maximum attribute type to be expected
 395 * @policy: validation policy
 396 */
 397static inline int nlmsg_validate(const struct nlmsghdr *nlh,
 398                                 int hdrlen, int maxtype,
 399                                 const struct nla_policy *policy)
 400{
 401        if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 402                return -EINVAL;
 403
 404        return nla_validate(nlmsg_attrdata(nlh, hdrlen),
 405                            nlmsg_attrlen(nlh, hdrlen), maxtype, policy);
 406}
 407
 408/**
 409 * nlmsg_report - need to report back to application?
 410 * @nlh: netlink message header
 411 *
 412 * Returns 1 if a report back to the application is requested.
 413 */
 414static inline int nlmsg_report(const struct nlmsghdr *nlh)
 415{
 416        return !!(nlh->nlmsg_flags & NLM_F_ECHO);
 417}
 418
 419/**
 420 * nlmsg_for_each_attr - iterate over a stream of attributes
 421 * @pos: loop counter, set to current attribute
 422 * @nlh: netlink message header
 423 * @hdrlen: length of familiy specific header
 424 * @rem: initialized to len, holds bytes currently remaining in stream
 425 */
 426#define nlmsg_for_each_attr(pos, nlh, hdrlen, rem) \
 427        nla_for_each_attr(pos, nlmsg_attrdata(nlh, hdrlen), \
 428                          nlmsg_attrlen(nlh, hdrlen), rem)
 429
 430/**
 431 * nlmsg_put - Add a new netlink message to an skb
 432 * @skb: socket buffer to store message in
 433 * @pid: netlink process id
 434 * @seq: sequence number of message
 435 * @type: message type
 436 * @payload: length of message payload
 437 * @flags: message flags
 438 *
 439 * Returns NULL if the tailroom of the skb is insufficient to store
 440 * the message header and payload.
 441 */
 442static inline struct nlmsghdr *nlmsg_put(struct sk_buff *skb, u32 pid, u32 seq,
 443                                         int type, int payload, int flags)
 444{
 445        if (unlikely(skb_tailroom(skb) < nlmsg_total_size(payload)))
 446                return NULL;
 447
 448        return __nlmsg_put(skb, pid, seq, type, payload, flags);
 449}
 450
 451/**
 452 * nlmsg_put_answer - Add a new callback based netlink message to an skb
 453 * @skb: socket buffer to store message in
 454 * @cb: netlink callback
 455 * @type: message type
 456 * @payload: length of message payload
 457 * @flags: message flags
 458 *
 459 * Returns NULL if the tailroom of the skb is insufficient to store
 460 * the message header and payload.
 461 */
 462static inline struct nlmsghdr *nlmsg_put_answer(struct sk_buff *skb,
 463                                                struct netlink_callback *cb,
 464                                                int type, int payload,
 465                                                int flags)
 466{
 467        return nlmsg_put(skb, NETLINK_CB(cb->skb).pid, cb->nlh->nlmsg_seq,
 468                         type, payload, flags);
 469}
 470
 471/**
 472 * nlmsg_new - Allocate a new netlink message
 473 * @payload: size of the message payload
 474 * @flags: the type of memory to allocate.
 475 *
 476 * Use NLMSG_DEFAULT_SIZE if the size of the payload isn't known
 477 * and a good default is needed.
 478 */
 479static inline struct sk_buff *nlmsg_new(size_t payload, gfp_t flags)
 480{
 481        return alloc_skb(nlmsg_total_size(payload), flags);
 482}
 483
 484/**
 485 * nlmsg_end - Finalize a netlink message
 486 * @skb: socket buffer the message is stored in
 487 * @nlh: netlink message header
 488 *
 489 * Corrects the netlink message header to include the appeneded
 490 * attributes. Only necessary if attributes have been added to
 491 * the message.
 492 *
 493 * Returns the total data length of the skb.
 494 */
 495static inline int nlmsg_end(struct sk_buff *skb, struct nlmsghdr *nlh)
 496{
 497        nlh->nlmsg_len = skb_tail_pointer(skb) - (unsigned char *)nlh;
 498
 499        return skb->len;
 500}
 501
 502/**
 503 * nlmsg_get_pos - return current position in netlink message
 504 * @skb: socket buffer the message is stored in
 505 *
 506 * Returns a pointer to the current tail of the message.
 507 */
 508static inline void *nlmsg_get_pos(struct sk_buff *skb)
 509{
 510        return skb_tail_pointer(skb);
 511}
 512
 513/**
 514 * nlmsg_trim - Trim message to a mark
 515 * @skb: socket buffer the message is stored in
 516 * @mark: mark to trim to
 517 *
 518 * Trims the message to the provided mark.
 519 */
 520static inline void nlmsg_trim(struct sk_buff *skb, const void *mark)
 521{
 522        if (mark)
 523                skb_trim(skb, (unsigned char *) mark - skb->data);
 524}
 525
 526/**
 527 * nlmsg_cancel - Cancel construction of a netlink message
 528 * @skb: socket buffer the message is stored in
 529 * @nlh: netlink message header
 530 *
 531 * Removes the complete netlink message including all
 532 * attributes from the socket buffer again.
 533 */
 534static inline void nlmsg_cancel(struct sk_buff *skb, struct nlmsghdr *nlh)
 535{
 536        nlmsg_trim(skb, nlh);
 537}
 538
 539/**
 540 * nlmsg_free - free a netlink message
 541 * @skb: socket buffer of netlink message
 542 */
 543static inline void nlmsg_free(struct sk_buff *skb)
 544{
 545        kfree_skb(skb);
 546}
 547
 548/**
 549 * nlmsg_multicast - multicast a netlink message
 550 * @sk: netlink socket to spread messages to
 551 * @skb: netlink message as socket buffer
 552 * @pid: own netlink pid to avoid sending to yourself
 553 * @group: multicast group id
 554 * @flags: allocation flags
 555 */
 556static inline int nlmsg_multicast(struct sock *sk, struct sk_buff *skb,
 557                                  u32 pid, unsigned int group, gfp_t flags)
 558{
 559        int err;
 560
 561        NETLINK_CB(skb).dst_group = group;
 562
 563        err = netlink_broadcast(sk, skb, pid, group, flags);
 564        if (err > 0)
 565                err = 0;
 566
 567        return err;
 568}
 569
 570/**
 571 * nlmsg_unicast - unicast a netlink message
 572 * @sk: netlink socket to spread message to
 573 * @skb: netlink message as socket buffer
 574 * @pid: netlink pid of the destination socket
 575 */
 576static inline int nlmsg_unicast(struct sock *sk, struct sk_buff *skb, u32 pid)
 577{
 578        int err;
 579
 580        err = netlink_unicast(sk, skb, pid, MSG_DONTWAIT);
 581        if (err > 0)
 582                err = 0;
 583
 584        return err;
 585}
 586
 587/**
 588 * nlmsg_for_each_msg - iterate over a stream of messages
 589 * @pos: loop counter, set to current message
 590 * @head: head of message stream
 591 * @len: length of message stream
 592 * @rem: initialized to len, holds bytes currently remaining in stream
 593 */
 594#define nlmsg_for_each_msg(pos, head, len, rem) \
 595        for (pos = head, rem = len; \
 596             nlmsg_ok(pos, rem); \
 597             pos = nlmsg_next(pos, &(rem)))
 598
 599/**
 600 * nl_dump_check_consistent - check if sequence is consistent and advertise if not
 601 * @cb: netlink callback structure that stores the sequence number
 602 * @nlh: netlink message header to write the flag to
 603 *
 604 * This function checks if the sequence (generation) number changed during dump
 605 * and if it did, advertises it in the netlink message header.
 606 *
 607 * The correct way to use it is to set cb->seq to the generation counter when
 608 * all locks for dumping have been acquired, and then call this function for
 609 * each message that is generated.
 610 *
 611 * Note that due to initialisation concerns, 0 is an invalid sequence number
 612 * and must not be used by code that uses this functionality.
 613 */
 614static inline void
 615nl_dump_check_consistent(struct netlink_callback *cb,
 616                         struct nlmsghdr *nlh)
 617{
 618        if (cb->prev_seq && cb->seq != cb->prev_seq)
 619                nlh->nlmsg_flags |= NLM_F_DUMP_INTR;
 620        cb->prev_seq = cb->seq;
 621}
 622
 623/**************************************************************************
 624 * Netlink Attributes
 625 **************************************************************************/
 626
 627/**
 628 * nla_attr_size - length of attribute not including padding
 629 * @payload: length of payload
 630 */
 631static inline int nla_attr_size(int payload)
 632{
 633        return NLA_HDRLEN + payload;
 634}
 635
 636/**
 637 * nla_total_size - total length of attribute including padding
 638 * @payload: length of payload
 639 */
 640static inline int nla_total_size(int payload)
 641{
 642        return NLA_ALIGN(nla_attr_size(payload));
 643}
 644
 645/**
 646 * nla_padlen - length of padding at the tail of attribute
 647 * @payload: length of payload
 648 */
 649static inline int nla_padlen(int payload)
 650{
 651        return nla_total_size(payload) - nla_attr_size(payload);
 652}
 653
 654/**
 655 * nla_type - attribute type
 656 * @nla: netlink attribute
 657 */
 658static inline int nla_type(const struct nlattr *nla)
 659{
 660        return nla->nla_type & NLA_TYPE_MASK;
 661}
 662
 663/**
 664 * nla_data - head of payload
 665 * @nla: netlink attribute
 666 */
 667static inline void *nla_data(const struct nlattr *nla)
 668{
 669        return (char *) nla + NLA_HDRLEN;
 670}
 671
 672/**
 673 * nla_len - length of payload
 674 * @nla: netlink attribute
 675 */
 676static inline int nla_len(const struct nlattr *nla)
 677{
 678        return nla->nla_len - NLA_HDRLEN;
 679}
 680
 681/**
 682 * nla_ok - check if the netlink attribute fits into the remaining bytes
 683 * @nla: netlink attribute
 684 * @remaining: number of bytes remaining in attribute stream
 685 */
 686static inline int nla_ok(const struct nlattr *nla, int remaining)
 687{
 688        return remaining >= (int) sizeof(*nla) &&
 689               nla->nla_len >= sizeof(*nla) &&
 690               nla->nla_len <= remaining;
 691}
 692
 693/**
 694 * nla_next - next netlink attribute in attribute stream
 695 * @nla: netlink attribute
 696 * @remaining: number of bytes remaining in attribute stream
 697 *
 698 * Returns the next netlink attribute in the attribute stream and
 699 * decrements remaining by the size of the current attribute.
 700 */
 701static inline struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
 702{
 703        int totlen = NLA_ALIGN(nla->nla_len);
 704
 705        *remaining -= totlen;
 706        return (struct nlattr *) ((char *) nla + totlen);
 707}
 708
 709/**
 710 * nla_find_nested - find attribute in a set of nested attributes
 711 * @nla: attribute containing the nested attributes
 712 * @attrtype: type of attribute to look for
 713 *
 714 * Returns the first attribute which matches the specified type.
 715 */
 716static inline struct nlattr *
 717nla_find_nested(const struct nlattr *nla, int attrtype)
 718{
 719        return nla_find(nla_data(nla), nla_len(nla), attrtype);
 720}
 721
 722/**
 723 * nla_parse_nested - parse nested attributes
 724 * @tb: destination array with maxtype+1 elements
 725 * @maxtype: maximum attribute type to be expected
 726 * @nla: attribute containing the nested attributes
 727 * @policy: validation policy
 728 *
 729 * See nla_parse()
 730 */
 731static inline int nla_parse_nested(struct nlattr *tb[], int maxtype,
 732                                   const struct nlattr *nla,
 733                                   const struct nla_policy *policy)
 734{
 735        return nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy);
 736}
 737
 738/**
 739 * nla_put_u8 - Add a u8 netlink attribute to a socket buffer
 740 * @skb: socket buffer to add attribute to
 741 * @attrtype: attribute type
 742 * @value: numeric value
 743 */
 744static inline int nla_put_u8(struct sk_buff *skb, int attrtype, u8 value)
 745{
 746        return nla_put(skb, attrtype, sizeof(u8), &value);
 747}
 748
 749/**
 750 * nla_put_u16 - Add a u16 netlink attribute to a socket buffer
 751 * @skb: socket buffer to add attribute to
 752 * @attrtype: attribute type
 753 * @value: numeric value
 754 */
 755static inline int nla_put_u16(struct sk_buff *skb, int attrtype, u16 value)
 756{
 757        return nla_put(skb, attrtype, sizeof(u16), &value);
 758}
 759
 760/**
 761 * nla_put_be16 - Add a __be16 netlink attribute to a socket buffer
 762 * @skb: socket buffer to add attribute to
 763 * @attrtype: attribute type
 764 * @value: numeric value
 765 */
 766static inline int nla_put_be16(struct sk_buff *skb, int attrtype, __be16 value)
 767{
 768        return nla_put(skb, attrtype, sizeof(__be16), &value);
 769}
 770
 771/**
 772 * nla_put_net16 - Add 16-bit network byte order netlink attribute to a socket buffer
 773 * @skb: socket buffer to add attribute to
 774 * @attrtype: attribute type
 775 * @value: numeric value
 776 */
 777static inline int nla_put_net16(struct sk_buff *skb, int attrtype, __be16 value)
 778{
 779        return nla_put_be16(skb, attrtype | NLA_F_NET_BYTEORDER, value);
 780}
 781
 782/**
 783 * nla_put_le16 - Add a __le16 netlink attribute to a socket buffer
 784 * @skb: socket buffer to add attribute to
 785 * @attrtype: attribute type
 786 * @value: numeric value
 787 */
 788static inline int nla_put_le16(struct sk_buff *skb, int attrtype, __le16 value)
 789{
 790        return nla_put(skb, attrtype, sizeof(__le16), &value);
 791}
 792
 793/**
 794 * nla_put_u32 - Add a u32 netlink attribute to a socket buffer
 795 * @skb: socket buffer to add attribute to
 796 * @attrtype: attribute type
 797 * @value: numeric value
 798 */
 799static inline int nla_put_u32(struct sk_buff *skb, int attrtype, u32 value)
 800{
 801        return nla_put(skb, attrtype, sizeof(u32), &value);
 802}
 803
 804/**
 805 * nla_put_be32 - Add a __be32 netlink attribute to a socket buffer
 806 * @skb: socket buffer to add attribute to
 807 * @attrtype: attribute type
 808 * @value: numeric value
 809 */
 810static inline int nla_put_be32(struct sk_buff *skb, int attrtype, __be32 value)
 811{
 812        return nla_put(skb, attrtype, sizeof(__be32), &value);
 813}
 814
 815/**
 816 * nla_put_net32 - Add 32-bit network byte order netlink attribute to a socket buffer
 817 * @skb: socket buffer to add attribute to
 818 * @attrtype: attribute type
 819 * @value: numeric value
 820 */
 821static inline int nla_put_net32(struct sk_buff *skb, int attrtype, __be32 value)
 822{
 823        return nla_put_be32(skb, attrtype | NLA_F_NET_BYTEORDER, value);
 824}
 825
 826/**
 827 * nla_put_le32 - Add a __le32 netlink attribute to a socket buffer
 828 * @skb: socket buffer to add attribute to
 829 * @attrtype: attribute type
 830 * @value: numeric value
 831 */
 832static inline int nla_put_le32(struct sk_buff *skb, int attrtype, __le32 value)
 833{
 834        return nla_put(skb, attrtype, sizeof(__le32), &value);
 835}
 836
 837/**
 838 * nla_put_u64 - Add a u64 netlink attribute to a socket buffer
 839 * @skb: socket buffer to add attribute to
 840 * @attrtype: attribute type
 841 * @value: numeric value
 842 */
 843static inline int nla_put_u64(struct sk_buff *skb, int attrtype, u64 value)
 844{
 845        return nla_put(skb, attrtype, sizeof(u64), &value);
 846}
 847
 848/**
 849 * nla_put_be64 - Add a __be64 netlink attribute to a socket buffer
 850 * @skb: socket buffer to add attribute to
 851 * @attrtype: attribute type
 852 * @value: numeric value
 853 */
 854static inline int nla_put_be64(struct sk_buff *skb, int attrtype, __be64 value)
 855{
 856        return nla_put(skb, attrtype, sizeof(__be64), &value);
 857}
 858
 859/**
 860 * nla_put_net64 - Add 64-bit network byte order netlink attribute to a socket buffer
 861 * @skb: socket buffer to add attribute to
 862 * @attrtype: attribute type
 863 * @value: numeric value
 864 */
 865static inline int nla_put_net64(struct sk_buff *skb, int attrtype, __be64 value)
 866{
 867        return nla_put_be64(skb, attrtype | NLA_F_NET_BYTEORDER, value);
 868}
 869
 870/**
 871 * nla_put_le64 - Add a __le64 netlink attribute to a socket buffer
 872 * @skb: socket buffer to add attribute to
 873 * @attrtype: attribute type
 874 * @value: numeric value
 875 */
 876static inline int nla_put_le64(struct sk_buff *skb, int attrtype, __le64 value)
 877{
 878        return nla_put(skb, attrtype, sizeof(__le64), &value);
 879}
 880
 881/**
 882 * nla_put_string - Add a string netlink attribute to a socket buffer
 883 * @skb: socket buffer to add attribute to
 884 * @attrtype: attribute type
 885 * @str: NUL terminated string
 886 */
 887static inline int nla_put_string(struct sk_buff *skb, int attrtype,
 888                                 const char *str)
 889{
 890        return nla_put(skb, attrtype, strlen(str) + 1, str);
 891}
 892
 893/**
 894 * nla_put_flag - Add a flag netlink attribute to a socket buffer
 895 * @skb: socket buffer to add attribute to
 896 * @attrtype: attribute type
 897 */
 898static inline int nla_put_flag(struct sk_buff *skb, int attrtype)
 899{
 900        return nla_put(skb, attrtype, 0, NULL);
 901}
 902
 903/**
 904 * nla_put_msecs - Add a msecs netlink attribute to a socket buffer
 905 * @skb: socket buffer to add attribute to
 906 * @attrtype: attribute type
 907 * @jiffies: number of msecs in jiffies
 908 */
 909static inline int nla_put_msecs(struct sk_buff *skb, int attrtype,
 910                                unsigned long jiffies)
 911{
 912        u64 tmp = jiffies_to_msecs(jiffies);
 913        return nla_put(skb, attrtype, sizeof(u64), &tmp);
 914}
 915
 916/**
 917 * nla_get_u32 - return payload of u32 attribute
 918 * @nla: u32 netlink attribute
 919 */
 920static inline u32 nla_get_u32(const struct nlattr *nla)
 921{
 922        return *(u32 *) nla_data(nla);
 923}
 924
 925/**
 926 * nla_get_be32 - return payload of __be32 attribute
 927 * @nla: __be32 netlink attribute
 928 */
 929static inline __be32 nla_get_be32(const struct nlattr *nla)
 930{
 931        return *(__be32 *) nla_data(nla);
 932}
 933
 934/**
 935 * nla_get_u16 - return payload of u16 attribute
 936 * @nla: u16 netlink attribute
 937 */
 938static inline u16 nla_get_u16(const struct nlattr *nla)
 939{
 940        return *(u16 *) nla_data(nla);
 941}
 942
 943/**
 944 * nla_get_be16 - return payload of __be16 attribute
 945 * @nla: __be16 netlink attribute
 946 */
 947static inline __be16 nla_get_be16(const struct nlattr *nla)
 948{
 949        return *(__be16 *) nla_data(nla);
 950}
 951
 952/**
 953 * nla_get_le16 - return payload of __le16 attribute
 954 * @nla: __le16 netlink attribute
 955 */
 956static inline __le16 nla_get_le16(const struct nlattr *nla)
 957{
 958        return *(__le16 *) nla_data(nla);
 959}
 960
 961/**
 962 * nla_get_u8 - return payload of u8 attribute
 963 * @nla: u8 netlink attribute
 964 */
 965static inline u8 nla_get_u8(const struct nlattr *nla)
 966{
 967        return *(u8 *) nla_data(nla);
 968}
 969
 970/**
 971 * nla_get_u64 - return payload of u64 attribute
 972 * @nla: u64 netlink attribute
 973 */
 974static inline u64 nla_get_u64(const struct nlattr *nla)
 975{
 976        u64 tmp;
 977
 978        nla_memcpy(&tmp, nla, sizeof(tmp));
 979
 980        return tmp;
 981}
 982
 983/**
 984 * nla_get_be64 - return payload of __be64 attribute
 985 * @nla: __be64 netlink attribute
 986 */
 987static inline __be64 nla_get_be64(const struct nlattr *nla)
 988{
 989        __be64 tmp;
 990
 991        nla_memcpy(&tmp, nla, sizeof(tmp));
 992
 993        return tmp;
 994}
 995
 996/**
 997 * nla_get_flag - return payload of flag attribute
 998 * @nla: flag netlink attribute
 999 */
1000static inline int nla_get_flag(const struct nlattr *nla)
1001{
1002        return !!nla;
1003}
1004
1005/**
1006 * nla_get_msecs - return payload of msecs attribute
1007 * @nla: msecs netlink attribute
1008 *
1009 * Returns the number of milliseconds in jiffies.
1010 */
1011static inline unsigned long nla_get_msecs(const struct nlattr *nla)
1012{
1013        u64 msecs = nla_get_u64(nla);
1014
1015        return msecs_to_jiffies((unsigned long) msecs);
1016}
1017
1018/**
1019 * nla_nest_start - Start a new level of nested attributes
1020 * @skb: socket buffer to add attributes to
1021 * @attrtype: attribute type of container
1022 *
1023 * Returns the container attribute
1024 */
1025static inline struct nlattr *nla_nest_start(struct sk_buff *skb, int attrtype)
1026{
1027        struct nlattr *start = (struct nlattr *)skb_tail_pointer(skb);
1028
1029        if (nla_put(skb, attrtype, 0, NULL) < 0)
1030                return NULL;
1031
1032        return start;
1033}
1034
1035/**
1036 * nla_nest_end - Finalize nesting of attributes
1037 * @skb: socket buffer the attributes are stored in
1038 * @start: container attribute
1039 *
1040 * Corrects the container attribute header to include the all
1041 * appeneded attributes.
1042 *
1043 * Returns the total data length of the skb.
1044 */
1045static inline int nla_nest_end(struct sk_buff *skb, struct nlattr *start)
1046{
1047        start->nla_len = skb_tail_pointer(skb) - (unsigned char *)start;
1048        return skb->len;
1049}
1050
1051/**
1052 * nla_nest_cancel - Cancel nesting of attributes
1053 * @skb: socket buffer the message is stored in
1054 * @start: container attribute
1055 *
1056 * Removes the container attribute and including all nested
1057 * attributes. Returns -EMSGSIZE
1058 */
1059static inline void nla_nest_cancel(struct sk_buff *skb, struct nlattr *start)
1060{
1061        nlmsg_trim(skb, start);
1062}
1063
1064/**
1065 * nla_validate_nested - Validate a stream of nested attributes
1066 * @start: container attribute
1067 * @maxtype: maximum attribute type to be expected
1068 * @policy: validation policy
1069 *
1070 * Validates all attributes in the nested attribute stream against the
1071 * specified policy. Attributes with a type exceeding maxtype will be
1072 * ignored. See documenation of struct nla_policy for more details.
1073 *
1074 * Returns 0 on success or a negative error code.
1075 */
1076static inline int nla_validate_nested(const struct nlattr *start, int maxtype,
1077                                      const struct nla_policy *policy)
1078{
1079        return nla_validate(nla_data(start), nla_len(start), maxtype, policy);
1080}
1081
1082/**
1083 * nla_for_each_attr - iterate over a stream of attributes
1084 * @pos: loop counter, set to current attribute
1085 * @head: head of attribute stream
1086 * @len: length of attribute stream
1087 * @rem: initialized to len, holds bytes currently remaining in stream
1088 */
1089#define nla_for_each_attr(pos, head, len, rem) \
1090        for (pos = head, rem = len; \
1091             nla_ok(pos, rem); \
1092             pos = nla_next(pos, &(rem)))
1093
1094/**
1095 * nla_for_each_nested - iterate over nested attributes
1096 * @pos: loop counter, set to current attribute
1097 * @nla: attribute containing the nested attributes
1098 * @rem: initialized to len, holds bytes currently remaining in stream
1099 */
1100#define nla_for_each_nested(pos, nla, rem) \
1101        nla_for_each_attr(pos, nla_data(nla), nla_len(nla), rem)
1102
1103#endif
1104
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