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_s8(skb, type, value)       add s8 attribute to skb
 102 *   nla_put_s16(skb, type, value)      add s16 attribute to skb
 103 *   nla_put_s32(skb, type, value)      add s32 attribute to skb
 104 *   nla_put_s64(skb, type, value)      add s64 attribute to skb
 105 *   nla_put_string(skb, type, str)     add string attribute to skb
 106 *   nla_put_flag(skb, type)            add flag attribute to skb
 107 *   nla_put_msecs(skb, type, jiffies)  add msecs attribute to skb
 108 *
 109 * Nested Attributes Construction:
 110 *   nla_nest_start(skb, type)          start a nested attribute
 111 *   nla_nest_end(skb, nla)             finalize a nested attribute
 112 *   nla_nest_cancel(skb, nla)          cancel nested attribute construction
 113 *
 114 * Attribute Length Calculations:
 115 *   nla_attr_size(payload)             length of attribute w/o padding
 116 *   nla_total_size(payload)            length of attribute w/ padding
 117 *   nla_padlen(payload)                length of padding
 118 *
 119 * Attribute Payload Access:
 120 *   nla_data(nla)                      head of attribute payload
 121 *   nla_len(nla)                       length of attribute payload
 122 *
 123 * Attribute Payload Access for Basic Types:
 124 *   nla_get_u8(nla)                    get payload for a u8 attribute
 125 *   nla_get_u16(nla)                   get payload for a u16 attribute
 126 *   nla_get_u32(nla)                   get payload for a u32 attribute
 127 *   nla_get_u64(nla)                   get payload for a u64 attribute
 128 *   nla_get_s8(nla)                    get payload for a s8 attribute
 129 *   nla_get_s16(nla)                   get payload for a s16 attribute
 130 *   nla_get_s32(nla)                   get payload for a s32 attribute
 131 *   nla_get_s64(nla)                   get payload for a s64 attribute
 132 *   nla_get_flag(nla)                  return 1 if flag is true
 133 *   nla_get_msecs(nla)                 get payload for a msecs attribute
 134 *
 135 * Attribute Misc:
 136 *   nla_memcpy(dest, nla, count)       copy attribute into memory
 137 *   nla_memcmp(nla, data, size)        compare attribute with memory area
 138 *   nla_strlcpy(dst, nla, size)        copy attribute to a sized string
 139 *   nla_strcmp(nla, str)               compare attribute with string
 140 *
 141 * Attribute Parsing:
 142 *   nla_ok(nla, remaining)             does nla fit into remaining bytes?
 143 *   nla_next(nla, remaining)           get next netlink attribute
 144 *   nla_validate()                     validate a stream of attributes
 145 *   nla_validate_nested()              validate a stream of nested attributes
 146 *   nla_find()                         find attribute in stream of attributes
 147 *   nla_find_nested()                  find attribute in nested attributes
 148 *   nla_parse()                        parse and validate stream of attrs
 149 *   nla_parse_nested()                 parse nested attribuets
 150 *   nla_for_each_attr()                loop over all attributes
 151 *   nla_for_each_nested()              loop over the nested attributes
 152 *=========================================================================
 153 */
 154
 155 /**
 156  * Standard attribute types to specify validation policy
 157  */
 158enum {
 159        NLA_UNSPEC,
 160        NLA_U8,
 161        NLA_U16,
 162        NLA_U32,
 163        NLA_U64,
 164        NLA_STRING,
 165        NLA_FLAG,
 166        NLA_MSECS,
 167        NLA_NESTED,
 168        NLA_NESTED_COMPAT,
 169        NLA_NUL_STRING,
 170        NLA_BINARY,
 171        NLA_S8,
 172        NLA_S16,
 173        NLA_S32,
 174        NLA_S64,
 175        __NLA_TYPE_MAX,
 176};
 177
 178#define NLA_TYPE_MAX (__NLA_TYPE_MAX - 1)
 179
 180/**
 181 * struct nla_policy - attribute validation policy
 182 * @type: Type of attribute or NLA_UNSPEC
 183 * @len: Type specific length of payload
 184 *
 185 * Policies are defined as arrays of this struct, the array must be
 186 * accessible by attribute type up to the highest identifier to be expected.
 187 *
 188 * Meaning of `len' field:
 189 *    NLA_STRING           Maximum length of string
 190 *    NLA_NUL_STRING       Maximum length of string (excluding NUL)
 191 *    NLA_FLAG             Unused
 192 *    NLA_BINARY           Maximum length of attribute payload
 193 *    NLA_NESTED           Don't use `len' field -- length verification is
 194 *                         done by checking len of nested header (or empty)
 195 *    NLA_NESTED_COMPAT    Minimum length of structure payload
 196 *    NLA_U8, NLA_U16,
 197 *    NLA_U32, NLA_U64,
 198 *    NLA_S8, NLA_S16,
 199 *    NLA_S32, NLA_S64,
 200 *    NLA_MSECS            Leaving the length field zero will verify the
 201 *                         given type fits, using it verifies minimum length
 202 *                         just like "All other"
 203 *    All other            Minimum length of attribute payload
 204 *
 205 * Example:
 206 * static const struct nla_policy my_policy[ATTR_MAX+1] = {
 207 *      [ATTR_FOO] = { .type = NLA_U16 },
 208 *      [ATTR_BAR] = { .type = NLA_STRING, .len = BARSIZ },
 209 *      [ATTR_BAZ] = { .len = sizeof(struct mystruct) },
 210 * };
 211 */
 212struct nla_policy {
 213        u16             type;
 214        u16             len;
 215};
 216
 217/**
 218 * struct nl_info - netlink source information
 219 * @nlh: Netlink message header of original request
 220 * @portid: Netlink PORTID of requesting application
 221 */
 222struct nl_info {
 223        struct nlmsghdr         *nlh;
 224        struct net              *nl_net;
 225        u32                     portid;
 226};
 227
 228extern int              netlink_rcv_skb(struct sk_buff *skb,
 229                                        int (*cb)(struct sk_buff *,
 230                                                  struct nlmsghdr *));
 231extern int              nlmsg_notify(struct sock *sk, struct sk_buff *skb,
 232                                     u32 portid, unsigned int group, int report,
 233                                     gfp_t flags);
 234
 235extern int              nla_validate(const struct nlattr *head,
 236                                     int len, int maxtype,
 237                                     const struct nla_policy *policy);
 238extern int              nla_parse(struct nlattr **tb, int maxtype,
 239                                  const struct nlattr *head, int len,
 240                                  const struct nla_policy *policy);
 241extern int              nla_policy_len(const struct nla_policy *, int);
 242extern struct nlattr *  nla_find(const struct nlattr *head,
 243                                 int len, int attrtype);
 244extern size_t           nla_strlcpy(char *dst, const struct nlattr *nla,
 245                                    size_t dstsize);
 246extern int              nla_memcpy(void *dest, const struct nlattr *src, int count);
 247extern int              nla_memcmp(const struct nlattr *nla, const void *data,
 248                                   size_t size);
 249extern int              nla_strcmp(const struct nlattr *nla, const char *str);
 250extern struct nlattr *  __nla_reserve(struct sk_buff *skb, int attrtype,
 251                                      int attrlen);
 252extern void *           __nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
 253extern struct nlattr *  nla_reserve(struct sk_buff *skb, int attrtype,
 254                                    int attrlen);
 255extern void *           nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
 256extern void             __nla_put(struct sk_buff *skb, int attrtype,
 257                                  int attrlen, const void *data);
 258extern void             __nla_put_nohdr(struct sk_buff *skb, int attrlen,
 259                                        const void *data);
 260extern int              nla_put(struct sk_buff *skb, int attrtype,
 261                                int attrlen, const void *data);
 262extern int              nla_put_nohdr(struct sk_buff *skb, int attrlen,
 263                                      const void *data);
 264extern int              nla_append(struct sk_buff *skb, int attrlen,
 265                                   const void *data);
 266
 267/**************************************************************************
 268 * Netlink Messages
 269 **************************************************************************/
 270
 271/**
 272 * nlmsg_msg_size - length of netlink message not including padding
 273 * @payload: length of message payload
 274 */
 275static inline int nlmsg_msg_size(int payload)
 276{
 277        return NLMSG_HDRLEN + payload;
 278}
 279
 280/**
 281 * nlmsg_total_size - length of netlink message including padding
 282 * @payload: length of message payload
 283 */
 284static inline int nlmsg_total_size(int payload)
 285{
 286        return NLMSG_ALIGN(nlmsg_msg_size(payload));
 287}
 288
 289/**
 290 * nlmsg_padlen - length of padding at the message's tail
 291 * @payload: length of message payload
 292 */
 293static inline int nlmsg_padlen(int payload)
 294{
 295        return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
 296}
 297
 298/**
 299 * nlmsg_data - head of message payload
 300 * @nlh: netlink message header
 301 */
 302static inline void *nlmsg_data(const struct nlmsghdr *nlh)
 303{
 304        return (unsigned char *) nlh + NLMSG_HDRLEN;
 305}
 306
 307/**
 308 * nlmsg_len - length of message payload
 309 * @nlh: netlink message header
 310 */
 311static inline int nlmsg_len(const struct nlmsghdr *nlh)
 312{
 313        return nlh->nlmsg_len - NLMSG_HDRLEN;
 314}
 315
 316/**
 317 * nlmsg_attrdata - head of attributes data
 318 * @nlh: netlink message header
 319 * @hdrlen: length of family specific header
 320 */
 321static inline struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh,
 322                                            int hdrlen)
 323{
 324        unsigned char *data = nlmsg_data(nlh);
 325        return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
 326}
 327
 328/**
 329 * nlmsg_attrlen - length of attributes data
 330 * @nlh: netlink message header
 331 * @hdrlen: length of family specific header
 332 */
 333static inline int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
 334{
 335        return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);
 336}
 337
 338/**
 339 * nlmsg_ok - check if the netlink message fits into the remaining bytes
 340 * @nlh: netlink message header
 341 * @remaining: number of bytes remaining in message stream
 342 */
 343static inline int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
 344{
 345        return (remaining >= (int) sizeof(struct nlmsghdr) &&
 346                nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
 347                nlh->nlmsg_len <= remaining);
 348}
 349
 350/**
 351 * nlmsg_next - next netlink message in message stream
 352 * @nlh: netlink message header
 353 * @remaining: number of bytes remaining in message stream
 354 *
 355 * Returns the next netlink message in the message stream and
 356 * decrements remaining by the size of the current message.
 357 */
 358static inline struct nlmsghdr *
 359nlmsg_next(const struct nlmsghdr *nlh, int *remaining)
 360{
 361        int totlen = NLMSG_ALIGN(nlh->nlmsg_len);
 362
 363        *remaining -= totlen;
 364
 365        return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
 366}
 367
 368/**
 369 * nlmsg_parse - parse attributes of a netlink message
 370 * @nlh: netlink message header
 371 * @hdrlen: length of family specific header
 372 * @tb: destination array with maxtype+1 elements
 373 * @maxtype: maximum attribute type to be expected
 374 * @policy: validation policy
 375 *
 376 * See nla_parse()
 377 */
 378static inline int nlmsg_parse(const struct nlmsghdr *nlh, int hdrlen,
 379                              struct nlattr *tb[], int maxtype,
 380                              const struct nla_policy *policy)
 381{
 382        if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 383                return -EINVAL;
 384
 385        return nla_parse(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
 386                         nlmsg_attrlen(nlh, hdrlen), policy);
 387}
 388
 389/**
 390 * nlmsg_find_attr - find a specific attribute in a netlink message
 391 * @nlh: netlink message header
 392 * @hdrlen: length of familiy specific header
 393 * @attrtype: type of attribute to look for
 394 *
 395 * Returns the first attribute which matches the specified type.
 396 */
 397static inline struct nlattr *nlmsg_find_attr(const struct nlmsghdr *nlh,
 398                                             int hdrlen, int attrtype)
 399{
 400        return nla_find(nlmsg_attrdata(nlh, hdrlen),
 401                        nlmsg_attrlen(nlh, hdrlen), attrtype);
 402}
 403
 404/**
 405 * nlmsg_validate - validate a netlink message including attributes
 406 * @nlh: netlinket message header
 407 * @hdrlen: length of familiy specific header
 408 * @maxtype: maximum attribute type to be expected
 409 * @policy: validation policy
 410 */
 411static inline int nlmsg_validate(const struct nlmsghdr *nlh,
 412                                 int hdrlen, int maxtype,
 413                                 const struct nla_policy *policy)
 414{
 415        if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 416                return -EINVAL;
 417
 418        return nla_validate(nlmsg_attrdata(nlh, hdrlen),
 419                            nlmsg_attrlen(nlh, hdrlen), maxtype, policy);
 420}
 421
 422/**
 423 * nlmsg_report - need to report back to application?
 424 * @nlh: netlink message header
 425 *
 426 * Returns 1 if a report back to the application is requested.
 427 */
 428static inline int nlmsg_report(const struct nlmsghdr *nlh)
 429{
 430        return !!(nlh->nlmsg_flags & NLM_F_ECHO);
 431}
 432
 433/**
 434 * nlmsg_for_each_attr - iterate over a stream of attributes
 435 * @pos: loop counter, set to current attribute
 436 * @nlh: netlink message header
 437 * @hdrlen: length of familiy specific header
 438 * @rem: initialized to len, holds bytes currently remaining in stream
 439 */
 440#define nlmsg_for_each_attr(pos, nlh, hdrlen, rem) \
 441        nla_for_each_attr(pos, nlmsg_attrdata(nlh, hdrlen), \
 442                          nlmsg_attrlen(nlh, hdrlen), rem)
 443
 444/**
 445 * nlmsg_put - Add a new netlink message to an skb
 446 * @skb: socket buffer to store message in
 447 * @portid: netlink process id
 448 * @seq: sequence number of message
 449 * @type: message type
 450 * @payload: length of message payload
 451 * @flags: message flags
 452 *
 453 * Returns NULL if the tailroom of the skb is insufficient to store
 454 * the message header and payload.
 455 */
 456static inline struct nlmsghdr *nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 457                                         int type, int payload, int flags)
 458{
 459        if (unlikely(skb_tailroom(skb) < nlmsg_total_size(payload)))
 460                return NULL;
 461
 462        return __nlmsg_put(skb, portid, seq, type, payload, flags);
 463}
 464
 465/**
 466 * nlmsg_put_answer - Add a new callback based netlink message to an skb
 467 * @skb: socket buffer to store message in
 468 * @cb: netlink callback
 469 * @type: message type
 470 * @payload: length of message payload
 471 * @flags: message flags
 472 *
 473 * Returns NULL if the tailroom of the skb is insufficient to store
 474 * the message header and payload.
 475 */
 476static inline struct nlmsghdr *nlmsg_put_answer(struct sk_buff *skb,
 477                                                struct netlink_callback *cb,
 478                                                int type, int payload,
 479                                                int flags)
 480{
 481        return nlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
 482                         type, payload, flags);
 483}
 484
 485/**
 486 * nlmsg_new - Allocate a new netlink message
 487 * @payload: size of the message payload
 488 * @flags: the type of memory to allocate.
 489 *
 490 * Use NLMSG_DEFAULT_SIZE if the size of the payload isn't known
 491 * and a good default is needed.
 492 */
 493static inline struct sk_buff *nlmsg_new(size_t payload, gfp_t flags)
 494{
 495        return alloc_skb(nlmsg_total_size(payload), flags);
 496}
 497
 498/**
 499 * nlmsg_end - Finalize a netlink message
 500 * @skb: socket buffer the message is stored in
 501 * @nlh: netlink message header
 502 *
 503 * Corrects the netlink message header to include the appeneded
 504 * attributes. Only necessary if attributes have been added to
 505 * the message.
 506 *
 507 * Returns the total data length of the skb.
 508 */
 509static inline int nlmsg_end(struct sk_buff *skb, struct nlmsghdr *nlh)
 510{
 511        nlh->nlmsg_len = skb_tail_pointer(skb) - (unsigned char *)nlh;
 512
 513        return skb->len;
 514}
 515
 516/**
 517 * nlmsg_get_pos - return current position in netlink message
 518 * @skb: socket buffer the message is stored in
 519 *
 520 * Returns a pointer to the current tail of the message.
 521 */
 522static inline void *nlmsg_get_pos(struct sk_buff *skb)
 523{
 524        return skb_tail_pointer(skb);
 525}
 526
 527/**
 528 * nlmsg_trim - Trim message to a mark
 529 * @skb: socket buffer the message is stored in
 530 * @mark: mark to trim to
 531 *
 532 * Trims the message to the provided mark.
 533 */
 534static inline void nlmsg_trim(struct sk_buff *skb, const void *mark)
 535{
 536        if (mark)
 537                skb_trim(skb, (unsigned char *) mark - skb->data);
 538}
 539
 540/**
 541 * nlmsg_cancel - Cancel construction of a netlink message
 542 * @skb: socket buffer the message is stored in
 543 * @nlh: netlink message header
 544 *
 545 * Removes the complete netlink message including all
 546 * attributes from the socket buffer again.
 547 */
 548static inline void nlmsg_cancel(struct sk_buff *skb, struct nlmsghdr *nlh)
 549{
 550        nlmsg_trim(skb, nlh);
 551}
 552
 553/**
 554 * nlmsg_free - free a netlink message
 555 * @skb: socket buffer of netlink message
 556 */
 557static inline void nlmsg_free(struct sk_buff *skb)
 558{
 559        kfree_skb(skb);
 560}
 561
 562/**
 563 * nlmsg_multicast - multicast a netlink message
 564 * @sk: netlink socket to spread messages to
 565 * @skb: netlink message as socket buffer
 566 * @portid: own netlink portid to avoid sending to yourself
 567 * @group: multicast group id
 568 * @flags: allocation flags
 569 */
 570static inline int nlmsg_multicast(struct sock *sk, struct sk_buff *skb,
 571                                  u32 portid, unsigned int group, gfp_t flags)
 572{
 573        int err;
 574
 575        NETLINK_CB(skb).dst_group = group;
 576
 577        err = netlink_broadcast(sk, skb, portid, group, flags);
 578        if (err > 0)
 579                err = 0;
 580
 581        return err;
 582}
 583
 584/**
 585 * nlmsg_unicast - unicast a netlink message
 586 * @sk: netlink socket to spread message to
 587 * @skb: netlink message as socket buffer
 588 * @portid: netlink portid of the destination socket
 589 */
 590static inline int nlmsg_unicast(struct sock *sk, struct sk_buff *skb, u32 portid)
 591{
 592        int err;
 593
 594        err = netlink_unicast(sk, skb, portid, MSG_DONTWAIT);
 595        if (err > 0)
 596                err = 0;
 597
 598        return err;
 599}
 600
 601/**
 602 * nlmsg_for_each_msg - iterate over a stream of messages
 603 * @pos: loop counter, set to current message
 604 * @head: head of message stream
 605 * @len: length of message stream
 606 * @rem: initialized to len, holds bytes currently remaining in stream
 607 */
 608#define nlmsg_for_each_msg(pos, head, len, rem) \
 609        for (pos = head, rem = len; \
 610             nlmsg_ok(pos, rem); \
 611             pos = nlmsg_next(pos, &(rem)))
 612
 613/**
 614 * nl_dump_check_consistent - check if sequence is consistent and advertise if not
 615 * @cb: netlink callback structure that stores the sequence number
 616 * @nlh: netlink message header to write the flag to
 617 *
 618 * This function checks if the sequence (generation) number changed during dump
 619 * and if it did, advertises it in the netlink message header.
 620 *
 621 * The correct way to use it is to set cb->seq to the generation counter when
 622 * all locks for dumping have been acquired, and then call this function for
 623 * each message that is generated.
 624 *
 625 * Note that due to initialisation concerns, 0 is an invalid sequence number
 626 * and must not be used by code that uses this functionality.
 627 */
 628static inline void
 629nl_dump_check_consistent(struct netlink_callback *cb,
 630                         struct nlmsghdr *nlh)
 631{
 632        if (cb->prev_seq && cb->seq != cb->prev_seq)
 633                nlh->nlmsg_flags |= NLM_F_DUMP_INTR;
 634        cb->prev_seq = cb->seq;
 635}
 636
 637/**************************************************************************
 638 * Netlink Attributes
 639 **************************************************************************/
 640
 641/**
 642 * nla_attr_size - length of attribute not including padding
 643 * @payload: length of payload
 644 */
 645static inline int nla_attr_size(int payload)
 646{
 647        return NLA_HDRLEN + payload;
 648}
 649
 650/**
 651 * nla_total_size - total length of attribute including padding
 652 * @payload: length of payload
 653 */
 654static inline int nla_total_size(int payload)
 655{
 656        return NLA_ALIGN(nla_attr_size(payload));
 657}
 658
 659/**
 660 * nla_padlen - length of padding at the tail of attribute
 661 * @payload: length of payload
 662 */
 663static inline int nla_padlen(int payload)
 664{
 665        return nla_total_size(payload) - nla_attr_size(payload);
 666}
 667
 668/**
 669 * nla_type - attribute type
 670 * @nla: netlink attribute
 671 */
 672static inline int nla_type(const struct nlattr *nla)
 673{
 674        return nla->nla_type & NLA_TYPE_MASK;
 675}
 676
 677/**
 678 * nla_data - head of payload
 679 * @nla: netlink attribute
 680 */
 681static inline void *nla_data(const struct nlattr *nla)
 682{
 683        return (char *) nla + NLA_HDRLEN;
 684}
 685
 686/**
 687 * nla_len - length of payload
 688 * @nla: netlink attribute
 689 */
 690static inline int nla_len(const struct nlattr *nla)
 691{
 692        return nla->nla_len - NLA_HDRLEN;
 693}
 694
 695/**
 696 * nla_ok - check if the netlink attribute fits into the remaining bytes
 697 * @nla: netlink attribute
 698 * @remaining: number of bytes remaining in attribute stream
 699 */
 700static inline int nla_ok(const struct nlattr *nla, int remaining)
 701{
 702        return remaining >= (int) sizeof(*nla) &&
 703               nla->nla_len >= sizeof(*nla) &&
 704               nla->nla_len <= remaining;
 705}
 706
 707/**
 708 * nla_next - next netlink attribute in attribute stream
 709 * @nla: netlink attribute
 710 * @remaining: number of bytes remaining in attribute stream
 711 *
 712 * Returns the next netlink attribute in the attribute stream and
 713 * decrements remaining by the size of the current attribute.
 714 */
 715static inline struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
 716{
 717        int totlen = NLA_ALIGN(nla->nla_len);
 718
 719        *remaining -= totlen;
 720        return (struct nlattr *) ((char *) nla + totlen);
 721}
 722
 723/**
 724 * nla_find_nested - find attribute in a set of nested attributes
 725 * @nla: attribute containing the nested attributes
 726 * @attrtype: type of attribute to look for
 727 *
 728 * Returns the first attribute which matches the specified type.
 729 */
 730static inline struct nlattr *
 731nla_find_nested(const struct nlattr *nla, int attrtype)
 732{
 733        return nla_find(nla_data(nla), nla_len(nla), attrtype);
 734}
 735
 736/**
 737 * nla_parse_nested - parse nested attributes
 738 * @tb: destination array with maxtype+1 elements
 739 * @maxtype: maximum attribute type to be expected
 740 * @nla: attribute containing the nested attributes
 741 * @policy: validation policy
 742 *
 743 * See nla_parse()
 744 */
 745static inline int nla_parse_nested(struct nlattr *tb[], int maxtype,
 746                                   const struct nlattr *nla,
 747                                   const struct nla_policy *policy)
 748{
 749        return nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy);
 750}
 751
 752/**
 753 * nla_put_u8 - Add a u8 netlink attribute to a socket buffer
 754 * @skb: socket buffer to add attribute to
 755 * @attrtype: attribute type
 756 * @value: numeric value
 757 */
 758static inline int nla_put_u8(struct sk_buff *skb, int attrtype, u8 value)
 759{
 760        return nla_put(skb, attrtype, sizeof(u8), &value);
 761}
 762
 763/**
 764 * nla_put_u16 - Add a u16 netlink attribute to a socket buffer
 765 * @skb: socket buffer to add attribute to
 766 * @attrtype: attribute type
 767 * @value: numeric value
 768 */
 769static inline int nla_put_u16(struct sk_buff *skb, int attrtype, u16 value)
 770{
 771        return nla_put(skb, attrtype, sizeof(u16), &value);
 772}
 773
 774/**
 775 * nla_put_be16 - Add a __be16 netlink attribute to a socket buffer
 776 * @skb: socket buffer to add attribute to
 777 * @attrtype: attribute type
 778 * @value: numeric value
 779 */
 780static inline int nla_put_be16(struct sk_buff *skb, int attrtype, __be16 value)
 781{
 782        return nla_put(skb, attrtype, sizeof(__be16), &value);
 783}
 784
 785/**
 786 * nla_put_net16 - Add 16-bit network byte order netlink attribute to a socket buffer
 787 * @skb: socket buffer to add attribute to
 788 * @attrtype: attribute type
 789 * @value: numeric value
 790 */
 791static inline int nla_put_net16(struct sk_buff *skb, int attrtype, __be16 value)
 792{
 793        return nla_put_be16(skb, attrtype | NLA_F_NET_BYTEORDER, value);
 794}
 795
 796/**
 797 * nla_put_le16 - Add a __le16 netlink attribute to a socket buffer
 798 * @skb: socket buffer to add attribute to
 799 * @attrtype: attribute type
 800 * @value: numeric value
 801 */
 802static inline int nla_put_le16(struct sk_buff *skb, int attrtype, __le16 value)
 803{
 804        return nla_put(skb, attrtype, sizeof(__le16), &value);
 805}
 806
 807/**
 808 * nla_put_u32 - Add a u32 netlink attribute to a socket buffer
 809 * @skb: socket buffer to add attribute to
 810 * @attrtype: attribute type
 811 * @value: numeric value
 812 */
 813static inline int nla_put_u32(struct sk_buff *skb, int attrtype, u32 value)
 814{
 815        return nla_put(skb, attrtype, sizeof(u32), &value);
 816}
 817
 818/**
 819 * nla_put_be32 - Add a __be32 netlink attribute to a socket buffer
 820 * @skb: socket buffer to add attribute to
 821 * @attrtype: attribute type
 822 * @value: numeric value
 823 */
 824static inline int nla_put_be32(struct sk_buff *skb, int attrtype, __be32 value)
 825{
 826        return nla_put(skb, attrtype, sizeof(__be32), &value);
 827}
 828
 829/**
 830 * nla_put_net32 - Add 32-bit network byte order netlink attribute to a socket buffer
 831 * @skb: socket buffer to add attribute to
 832 * @attrtype: attribute type
 833 * @value: numeric value
 834 */
 835static inline int nla_put_net32(struct sk_buff *skb, int attrtype, __be32 value)
 836{
 837        return nla_put_be32(skb, attrtype | NLA_F_NET_BYTEORDER, value);
 838}
 839
 840/**
 841 * nla_put_le32 - Add a __le32 netlink attribute to a socket buffer
 842 * @skb: socket buffer to add attribute to
 843 * @attrtype: attribute type
 844 * @value: numeric value
 845 */
 846static inline int nla_put_le32(struct sk_buff *skb, int attrtype, __le32 value)
 847{
 848        return nla_put(skb, attrtype, sizeof(__le32), &value);
 849}
 850
 851/**
 852 * nla_put_u64 - Add a u64 netlink attribute to a socket buffer
 853 * @skb: socket buffer to add attribute to
 854 * @attrtype: attribute type
 855 * @value: numeric value
 856 */
 857static inline int nla_put_u64(struct sk_buff *skb, int attrtype, u64 value)
 858{
 859        return nla_put(skb, attrtype, sizeof(u64), &value);
 860}
 861
 862/**
 863 * nla_put_be64 - Add a __be64 netlink attribute to a socket buffer
 864 * @skb: socket buffer to add attribute to
 865 * @attrtype: attribute type
 866 * @value: numeric value
 867 */
 868static inline int nla_put_be64(struct sk_buff *skb, int attrtype, __be64 value)
 869{
 870        return nla_put(skb, attrtype, sizeof(__be64), &value);
 871}
 872
 873/**
 874 * nla_put_net64 - Add 64-bit network byte order netlink attribute to a socket buffer
 875 * @skb: socket buffer to add attribute to
 876 * @attrtype: attribute type
 877 * @value: numeric value
 878 */
 879static inline int nla_put_net64(struct sk_buff *skb, int attrtype, __be64 value)
 880{
 881        return nla_put_be64(skb, attrtype | NLA_F_NET_BYTEORDER, value);
 882}
 883
 884/**
 885 * nla_put_le64 - Add a __le64 netlink attribute to a socket buffer
 886 * @skb: socket buffer to add attribute to
 887 * @attrtype: attribute type
 888 * @value: numeric value
 889 */
 890static inline int nla_put_le64(struct sk_buff *skb, int attrtype, __le64 value)
 891{
 892        return nla_put(skb, attrtype, sizeof(__le64), &value);
 893}
 894
 895/**
 896 * nla_put_s8 - Add a s8 netlink attribute to a socket buffer
 897 * @skb: socket buffer to add attribute to
 898 * @attrtype: attribute type
 899 * @value: numeric value
 900 */
 901static inline int nla_put_s8(struct sk_buff *skb, int attrtype, s8 value)
 902{
 903        return nla_put(skb, attrtype, sizeof(s8), &value);
 904}
 905
 906/**
 907 * nla_put_s16 - Add a s16 netlink attribute to a socket buffer
 908 * @skb: socket buffer to add attribute to
 909 * @attrtype: attribute type
 910 * @value: numeric value
 911 */
 912static inline int nla_put_s16(struct sk_buff *skb, int attrtype, s16 value)
 913{
 914        return nla_put(skb, attrtype, sizeof(s16), &value);
 915}
 916
 917/**
 918 * nla_put_s32 - Add a s32 netlink attribute to a socket buffer
 919 * @skb: socket buffer to add attribute to
 920 * @attrtype: attribute type
 921 * @value: numeric value
 922 */
 923static inline int nla_put_s32(struct sk_buff *skb, int attrtype, s32 value)
 924{
 925        return nla_put(skb, attrtype, sizeof(s32), &value);
 926}
 927
 928/**
 929 * nla_put_s64 - Add a s64 netlink attribute to a socket buffer
 930 * @skb: socket buffer to add attribute to
 931 * @attrtype: attribute type
 932 * @value: numeric value
 933 */
 934static inline int nla_put_s64(struct sk_buff *skb, int attrtype, s64 value)
 935{
 936        return nla_put(skb, attrtype, sizeof(s64), &value);
 937}
 938
 939/**
 940 * nla_put_string - Add a string netlink attribute to a socket buffer
 941 * @skb: socket buffer to add attribute to
 942 * @attrtype: attribute type
 943 * @str: NUL terminated string
 944 */
 945static inline int nla_put_string(struct sk_buff *skb, int attrtype,
 946                                 const char *str)
 947{
 948        return nla_put(skb, attrtype, strlen(str) + 1, str);
 949}
 950
 951/**
 952 * nla_put_flag - Add a flag netlink attribute to a socket buffer
 953 * @skb: socket buffer to add attribute to
 954 * @attrtype: attribute type
 955 */
 956static inline int nla_put_flag(struct sk_buff *skb, int attrtype)
 957{
 958        return nla_put(skb, attrtype, 0, NULL);
 959}
 960
 961/**
 962 * nla_put_msecs - Add a msecs netlink attribute to a socket buffer
 963 * @skb: socket buffer to add attribute to
 964 * @attrtype: attribute type
 965 * @jiffies: number of msecs in jiffies
 966 */
 967static inline int nla_put_msecs(struct sk_buff *skb, int attrtype,
 968                                unsigned long jiffies)
 969{
 970        u64 tmp = jiffies_to_msecs(jiffies);
 971        return nla_put(skb, attrtype, sizeof(u64), &tmp);
 972}
 973
 974/**
 975 * nla_get_u32 - return payload of u32 attribute
 976 * @nla: u32 netlink attribute
 977 */
 978static inline u32 nla_get_u32(const struct nlattr *nla)
 979{
 980        return *(u32 *) nla_data(nla);
 981}
 982
 983/**
 984 * nla_get_be32 - return payload of __be32 attribute
 985 * @nla: __be32 netlink attribute
 986 */
 987static inline __be32 nla_get_be32(const struct nlattr *nla)
 988{
 989        return *(__be32 *) nla_data(nla);
 990}
 991
 992/**
 993 * nla_get_u16 - return payload of u16 attribute
 994 * @nla: u16 netlink attribute
 995 */
 996static inline u16 nla_get_u16(const struct nlattr *nla)
 997{
 998        return *(u16 *) nla_data(nla);
 999}
1000
1001/**
1002 * nla_get_be16 - return payload of __be16 attribute
1003 * @nla: __be16 netlink attribute
1004 */
1005static inline __be16 nla_get_be16(const struct nlattr *nla)
1006{
1007        return *(__be16 *) nla_data(nla);
1008}
1009
1010/**
1011 * nla_get_le16 - return payload of __le16 attribute
1012 * @nla: __le16 netlink attribute
1013 */
1014static inline __le16 nla_get_le16(const struct nlattr *nla)
1015{
1016        return *(__le16 *) nla_data(nla);
1017}
1018
1019/**
1020 * nla_get_u8 - return payload of u8 attribute
1021 * @nla: u8 netlink attribute
1022 */
1023static inline u8 nla_get_u8(const struct nlattr *nla)
1024{
1025        return *(u8 *) nla_data(nla);
1026}
1027
1028/**
1029 * nla_get_u64 - return payload of u64 attribute
1030 * @nla: u64 netlink attribute
1031 */
1032static inline u64 nla_get_u64(const struct nlattr *nla)
1033{
1034        u64 tmp;
1035
1036        nla_memcpy(&tmp, nla, sizeof(tmp));
1037
1038        return tmp;
1039}
1040
1041/**
1042 * nla_get_be64 - return payload of __be64 attribute
1043 * @nla: __be64 netlink attribute
1044 */
1045static inline __be64 nla_get_be64(const struct nlattr *nla)
1046{
1047        __be64 tmp;
1048
1049        nla_memcpy(&tmp, nla, sizeof(tmp));
1050
1051        return tmp;
1052}
1053
1054/**
1055 * nla_get_s32 - return payload of s32 attribute
1056 * @nla: s32 netlink attribute
1057 */
1058static inline s32 nla_get_s32(const struct nlattr *nla)
1059{
1060        return *(s32 *) nla_data(nla);
1061}
1062
1063/**
1064 * nla_get_s16 - return payload of s16 attribute
1065 * @nla: s16 netlink attribute
1066 */
1067static inline s16 nla_get_s16(const struct nlattr *nla)
1068{
1069        return *(s16 *) nla_data(nla);
1070}
1071
1072/**
1073 * nla_get_s8 - return payload of s8 attribute
1074 * @nla: s8 netlink attribute
1075 */
1076static inline s8 nla_get_s8(const struct nlattr *nla)
1077{
1078        return *(s8 *) nla_data(nla);
1079}
1080
1081/**
1082 * nla_get_s64 - return payload of s64 attribute
1083 * @nla: s64 netlink attribute
1084 */
1085static inline s64 nla_get_s64(const struct nlattr *nla)
1086{
1087        s64 tmp;
1088
1089        nla_memcpy(&tmp, nla, sizeof(tmp));
1090
1091        return tmp;
1092}
1093
1094/**
1095 * nla_get_flag - return payload of flag attribute
1096 * @nla: flag netlink attribute
1097 */
1098static inline int nla_get_flag(const struct nlattr *nla)
1099{
1100        return !!nla;
1101}
1102
1103/**
1104 * nla_get_msecs - return payload of msecs attribute
1105 * @nla: msecs netlink attribute
1106 *
1107 * Returns the number of milliseconds in jiffies.
1108 */
1109static inline unsigned long nla_get_msecs(const struct nlattr *nla)
1110{
1111        u64 msecs = nla_get_u64(nla);
1112
1113        return msecs_to_jiffies((unsigned long) msecs);
1114}
1115
1116/**
1117 * nla_nest_start - Start a new level of nested attributes
1118 * @skb: socket buffer to add attributes to
1119 * @attrtype: attribute type of container
1120 *
1121 * Returns the container attribute
1122 */
1123static inline struct nlattr *nla_nest_start(struct sk_buff *skb, int attrtype)
1124{
1125        struct nlattr *start = (struct nlattr *)skb_tail_pointer(skb);
1126
1127        if (nla_put(skb, attrtype, 0, NULL) < 0)
1128                return NULL;
1129
1130        return start;
1131}
1132
1133/**
1134 * nla_nest_end - Finalize nesting of attributes
1135 * @skb: socket buffer the attributes are stored in
1136 * @start: container attribute
1137 *
1138 * Corrects the container attribute header to include the all
1139 * appeneded attributes.
1140 *
1141 * Returns the total data length of the skb.
1142 */
1143static inline int nla_nest_end(struct sk_buff *skb, struct nlattr *start)
1144{
1145        start->nla_len = skb_tail_pointer(skb) - (unsigned char *)start;
1146        return skb->len;
1147}
1148
1149/**
1150 * nla_nest_cancel - Cancel nesting of attributes
1151 * @skb: socket buffer the message is stored in
1152 * @start: container attribute
1153 *
1154 * Removes the container attribute and including all nested
1155 * attributes. Returns -EMSGSIZE
1156 */
1157static inline void nla_nest_cancel(struct sk_buff *skb, struct nlattr *start)
1158{
1159        nlmsg_trim(skb, start);
1160}
1161
1162/**
1163 * nla_validate_nested - Validate a stream of nested attributes
1164 * @start: container attribute
1165 * @maxtype: maximum attribute type to be expected
1166 * @policy: validation policy
1167 *
1168 * Validates all attributes in the nested attribute stream against the
1169 * specified policy. Attributes with a type exceeding maxtype will be
1170 * ignored. See documenation of struct nla_policy for more details.
1171 *
1172 * Returns 0 on success or a negative error code.
1173 */
1174static inline int nla_validate_nested(const struct nlattr *start, int maxtype,
1175                                      const struct nla_policy *policy)
1176{
1177        return nla_validate(nla_data(start), nla_len(start), maxtype, policy);
1178}
1179
1180/**
1181 * nla_for_each_attr - iterate over a stream of attributes
1182 * @pos: loop counter, set to current attribute
1183 * @head: head of attribute stream
1184 * @len: length of attribute stream
1185 * @rem: initialized to len, holds bytes currently remaining in stream
1186 */
1187#define nla_for_each_attr(pos, head, len, rem) \
1188        for (pos = head, rem = len; \
1189             nla_ok(pos, rem); \
1190             pos = nla_next(pos, &(rem)))
1191
1192/**
1193 * nla_for_each_nested - iterate over nested attributes
1194 * @pos: loop counter, set to current attribute
1195 * @nla: attribute containing the nested attributes
1196 * @rem: initialized to len, holds bytes currently remaining in stream
1197 */
1198#define nla_for_each_nested(pos, nla, rem) \
1199        nla_for_each_attr(pos, nla_data(nla), nla_len(nla), rem)
1200
1201#endif
1202
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