include/net/netlink.h

   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   */
 150 enum {
 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  */
 198 struct 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  */
 208 struct nl_info {
 209         struct nlmsghdr         *nlh;
 210         struct net              *nl_net;
 211         u32                     pid;
 212 };
 213
 214 extern int              netlink_rcv_skb(struct sk_buff *skb,
 215                                         int (*cb)(struct sk_buff *,
 216                                                   struct nlmsghdr *));
 217 extern int              nlmsg_notify(struct sock *sk, struct sk_buff *skb,
 218                                      u32 pid, unsigned int group, int report,
 219                                      gfp_t flags);
 220
 221 extern int              nla_validate(const struct nlattr *head,
 222                                      int len, int maxtype,
 223                                      const struct nla_policy *policy);
 224 extern int              nla_parse(struct nlattr **tb, int maxtype,
 225                                   const struct nlattr *head, int len,
 226                                   const struct nla_policy *policy);
 227 extern int              nla_policy_len(const struct nla_policy *, int);
 228 extern struct nlattr *  nla_find(const struct nlattr *head,
 229                                  int len, int attrtype);
 230 extern size_t           nla_strlcpy(char *dst, const struct nlattr *nla,
 231                                     size_t dstsize);
 232 extern int              nla_memcpy(void *dest, const struct nlattr *src, int count);
 233 extern int              nla_memcmp(const struct nlattr *nla, const void *data,
 234                                    size_t size);
 235 extern int              nla_strcmp(const struct nlattr *nla, const char *str);
 236 extern struct nlattr *  __nla_reserve(struct sk_buff *skb, int attrtype,
 237                                       int attrlen);
 238 extern void *           __nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
 239 extern struct nlattr *  nla_reserve(struct sk_buff *skb, int attrtype,
 240                                     int attrlen);
 241 extern void *           nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
 242 extern void             __nla_put(struct sk_buff *skb, int attrtype,
 243                                   int attrlen, const void *data);
 244 extern void             __nla_put_nohdr(struct sk_buff *skb, int attrlen,
 245                                         const void *data);
 246 extern int              nla_put(struct sk_buff *skb, int attrtype,
 247                                 int attrlen, const void *data);
 248 extern int              nla_put_nohdr(struct sk_buff *skb, int attrlen,
 249                                       const void *data);
 250 extern 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  */
 261 static 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  */
 270 static 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  */
 279 static 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  */
 288 static 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  */
 297 static 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  */
 307 static 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  */
 319 static 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  */
 329 static 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  */
 344 static inline struct nlmsghdr *
 345 nlmsg_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  */
 364 static 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  */
 383 static 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  */
 397 static 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  */
 414 static 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  */
 442 static 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  */
 462 static 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  */
 479 static 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  */
 495 static 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  */
 508 static 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  */
 520 static 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  */
 534 static 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  */
 543 static 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  */
 556 static 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  */
 576 static 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  */
 614 static inline void
 615 nl_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  */
 631 static 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  */
 640 static 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  */
 649 static 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  */
 658 static 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  */
 667 static 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  */
 676 static 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  */
 686 static 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  */
 701 static 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  */
 716 static inline struct nlattr *
 717 nla_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  */
 731 static 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  */
 744 static 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  */
 755 static 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  */
 766 static 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  */
 777 static 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  */
 788 static 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  */
 799 static 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  */
 810 static 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  */
 821 static 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  */
 832 static 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  */
 843 static 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  */
 854 static 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  */
 865 static 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  */
 876 static 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  */
 887 static 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  */
 898 static 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  */
 909 static 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  */
 920 static 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  */
 929 static 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  */
 938 static 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  */
 947 static 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  */
 956 static 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  */
 965 static 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  */
 974 static 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  */
 987 static 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  */
1000 static 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  */
1011 static 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  */
1025 static 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  */
1045 static 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  */
1059 static 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  */
1076 static 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