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()                        finanlize 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  * Exceptions Based Attribute Construction:
 106  *   NLA_PUT(skb, type, len, data)      add attribute to skb
 107  *   NLA_PUT_U8(skb, type, value)       add u8 attribute to skb
 108  *   NLA_PUT_U16(skb, type, value)      add u16 attribute to skb
 109  *   NLA_PUT_U32(skb, type, value)      add u32 attribute to skb
 110  *   NLA_PUT_U64(skb, type, value)      add u64 attribute to skb
 111  *   NLA_PUT_STRING(skb, type, str)     add string attribute to skb
 112  *   NLA_PUT_FLAG(skb, type)            add flag attribute to skb
 113  *   NLA_PUT_MSECS(skb, type, jiffies)  add msecs attribute to skb
 114  *
 115  *   The meaning of these functions is equal to their lower case
 116  *   variants but they jump to the label nla_put_failure in case
 117  *   of a failure.
 118  *
 119  * Nested Attributes Construction:
 120  *   nla_nest_start(skb, type)          start a nested attribute
 121  *   nla_nest_end(skb, nla)             finalize a nested attribute
 122  *   nla_nest_cancel(skb, nla)          cancel nested attribute construction
 123  *
 124  * Attribute Length Calculations:
 125  *   nla_attr_size(payload)             length of attribute w/o padding
 126  *   nla_total_size(payload)            length of attribute w/ padding
 127  *   nla_padlen(payload)                length of padding
 128  *
 129  * Attribute Payload Access:
 130  *   nla_data(nla)                      head of attribute payload
 131  *   nla_len(nla)                       length of attribute payload
 132  *
 133  * Attribute Payload Access for Basic Types:
 134  *   nla_get_u8(nla)                    get payload for a u8 attribute
 135  *   nla_get_u16(nla)                   get payload for a u16 attribute
 136  *   nla_get_u32(nla)                   get payload for a u32 attribute
 137  *   nla_get_u64(nla)                   get payload for a u64 attribute
 138  *   nla_get_flag(nla)                  return 1 if flag is true
 139  *   nla_get_msecs(nla)                 get payload for a msecs attribute
 140  *
 141  * Attribute Misc:
 142  *   nla_memcpy(dest, nla, count)       copy attribute into memory
 143  *   nla_memcmp(nla, data, size)        compare attribute with memory area
 144  *   nla_strlcpy(dst, nla, size)        copy attribute to a sized string
 145  *   nla_strcmp(nla, str)               compare attribute with string
 146  *
 147  * Attribute Parsing:
 148  *   nla_ok(nla, remaining)             does nla fit into remaining bytes?
 149  *   nla_next(nla, remaining)           get next netlink attribute
 150  *   nla_validate()                     validate a stream of attributes
 151  *   nla_validate_nested()              validate a stream of nested attributes
 152  *   nla_find()                         find attribute in stream of attributes
 153  *   nla_find_nested()                  find attribute in nested attributes
 154  *   nla_parse()                        parse and validate stream of attrs
 155  *   nla_parse_nested()                 parse nested attribuets
 156  *   nla_for_each_attr()                loop over all attributes
 157  *   nla_for_each_nested()              loop over the nested attributes
 158  *=========================================================================
 159  */
 160
 161  /**
 162   * Standard attribute types to specify validation policy
 163   */
 164 enum {
 165         NLA_UNSPEC,
 166         NLA_U8,
 167         NLA_U16,
 168         NLA_U32,
 169         NLA_U64,
 170         NLA_STRING,
 171         NLA_FLAG,
 172         NLA_MSECS,
 173         NLA_NESTED,
 174         NLA_NESTED_COMPAT,
 175         NLA_NUL_STRING,
 176         NLA_BINARY,
 177         __NLA_TYPE_MAX,
 178 };
 179
 180 #define NLA_TYPE_MAX (__NLA_TYPE_MAX - 1)
 181
 182 /**
 183  * struct nla_policy - attribute validation policy
 184  * @type: Type of attribute or NLA_UNSPEC
 185  * @len: Type specific length of payload
 186  *
 187  * Policies are defined as arrays of this struct, the array must be
 188  * accessible by attribute type up to the highest identifier to be expected.
 189  *
 190  * Meaning of `len' field:
 191  *    NLA_STRING           Maximum length of string
 192  *    NLA_NUL_STRING       Maximum length of string (excluding NUL)
 193  *    NLA_FLAG             Unused
 194  *    NLA_BINARY           Maximum length of attribute payload
 195  *    NLA_NESTED_COMPAT    Exact length of structure payload
 196  *    All other            Exact length of attribute payload
 197  *
 198  * Example:
 199  * static struct nla_policy my_policy[ATTR_MAX+1] __read_mostly = {
 200  *      [ATTR_FOO] = { .type = NLA_U16 },
 201  *      [ATTR_BAR] = { .type = NLA_STRING, .len = BARSIZ },
 202  *      [ATTR_BAZ] = { .len = sizeof(struct mystruct) },
 203  * };
 204  */
 205 struct nla_policy {
 206         u16             type;
 207         u16             len;
 208 };
 209
 210 /**
 211  * struct nl_info - netlink source information
 212  * @nlh: Netlink message header of original request
 213  * @pid: Netlink PID of requesting application
 214  */
 215 struct nl_info {
 216         struct nlmsghdr         *nlh;
 217         struct net              *nl_net;
 218         u32                     pid;
 219 };
 220
 221 extern int              netlink_rcv_skb(struct sk_buff *skb,
 222                                         int (*cb)(struct sk_buff *,
 223                                                   struct nlmsghdr *));
 224 extern int              nlmsg_notify(struct sock *sk, struct sk_buff *skb,
 225                                      u32 pid, unsigned int group, int report,
 226                                      gfp_t flags);
 227
 228 extern int              nla_validate(struct nlattr *head, int len, int maxtype,
 229                                      const struct nla_policy *policy);
 230 extern int              nla_parse(struct nlattr *tb[], int maxtype,
 231                                   struct nlattr *head, int len,
 232                                   const struct nla_policy *policy);
 233 extern int              nla_policy_len(const struct nla_policy *, int);
 234 extern struct nlattr *  nla_find(struct nlattr *head, int len, int attrtype);
 235 extern size_t           nla_strlcpy(char *dst, const struct nlattr *nla,
 236                                     size_t dstsize);
 237 extern int              nla_memcpy(void *dest, const struct nlattr *src, int count);
 238 extern int              nla_memcmp(const struct nlattr *nla, const void *data,
 239                                    size_t size);
 240 extern int              nla_strcmp(const struct nlattr *nla, const char *str);
 241 extern struct nlattr *  __nla_reserve(struct sk_buff *skb, int attrtype,
 242                                       int attrlen);
 243 extern void *           __nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
 244 extern struct nlattr *  nla_reserve(struct sk_buff *skb, int attrtype,
 245                                     int attrlen);
 246 extern void *           nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
 247 extern void             __nla_put(struct sk_buff *skb, int attrtype,
 248                                   int attrlen, const void *data);
 249 extern void             __nla_put_nohdr(struct sk_buff *skb, int attrlen,
 250                                         const void *data);
 251 extern int              nla_put(struct sk_buff *skb, int attrtype,
 252                                 int attrlen, const void *data);
 253 extern int              nla_put_nohdr(struct sk_buff *skb, int attrlen,
 254                                       const void *data);
 255 extern int              nla_append(struct sk_buff *skb, int attrlen,
 256                                    const void *data);
 257
 258 /**************************************************************************
 259  * Netlink Messages
 260  **************************************************************************/
 261
 262 /**
 263  * nlmsg_msg_size - length of netlink message not including padding
 264  * @payload: length of message payload
 265  */
 266 static inline int nlmsg_msg_size(int payload)
 267 {
 268         return NLMSG_HDRLEN + payload;
 269 }
 270
 271 /**
 272  * nlmsg_total_size - length of netlink message including padding
 273  * @payload: length of message payload
 274  */
 275 static inline int nlmsg_total_size(int payload)
 276 {
 277         return NLMSG_ALIGN(nlmsg_msg_size(payload));
 278 }
 279
 280 /**
 281  * nlmsg_padlen - length of padding at the message's tail
 282  * @payload: length of message payload
 283  */
 284 static inline int nlmsg_padlen(int payload)
 285 {
 286         return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
 287 }
 288
 289 /**
 290  * nlmsg_data - head of message payload
 291  * @nlh: netlink messsage header
 292  */
 293 static inline void *nlmsg_data(const struct nlmsghdr *nlh)
 294 {
 295         return (unsigned char *) nlh + NLMSG_HDRLEN;
 296 }
 297
 298 /**
 299  * nlmsg_len - length of message payload
 300  * @nlh: netlink message header
 301  */
 302 static inline int nlmsg_len(const struct nlmsghdr *nlh)
 303 {
 304         return nlh->nlmsg_len - NLMSG_HDRLEN;
 305 }
 306
 307 /**
 308  * nlmsg_attrdata - head of attributes data
 309  * @nlh: netlink message header
 310  * @hdrlen: length of family specific header
 311  */
 312 static inline struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh,
 313                                             int hdrlen)
 314 {
 315         unsigned char *data = nlmsg_data(nlh);
 316         return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
 317 }
 318
 319 /**
 320  * nlmsg_attrlen - length of attributes data
 321  * @nlh: netlink message header
 322  * @hdrlen: length of family specific header
 323  */
 324 static inline int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
 325 {
 326         return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);
 327 }
 328
 329 /**
 330  * nlmsg_ok - check if the netlink message fits into the remaining bytes
 331  * @nlh: netlink message header
 332  * @remaining: number of bytes remaining in message stream
 333  */
 334 static inline int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
 335 {
 336         return (remaining >= (int) sizeof(struct nlmsghdr) &&
 337                 nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
 338                 nlh->nlmsg_len <= remaining);
 339 }
 340
 341 /**
 342  * nlmsg_next - next netlink message in message stream
 343  * @nlh: netlink message header
 344  * @remaining: number of bytes remaining in message stream
 345  *
 346  * Returns the next netlink message in the message stream and
 347  * decrements remaining by the size of the current message.
 348  */
 349 static inline struct nlmsghdr *nlmsg_next(struct nlmsghdr *nlh, int *remaining)
 350 {
 351         int totlen = NLMSG_ALIGN(nlh->nlmsg_len);
 352
 353         *remaining -= totlen;
 354
 355         return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
 356 }
 357
 358 /**
 359  * nlmsg_parse - parse attributes of a netlink message
 360  * @nlh: netlink message header
 361  * @hdrlen: length of family specific header
 362  * @tb: destination array with maxtype+1 elements
 363  * @maxtype: maximum attribute type to be expected
 364  * @policy: validation policy
 365  *
 366  * See nla_parse()
 367  */
 368 static inline int nlmsg_parse(const struct nlmsghdr *nlh, int hdrlen,
 369                               struct nlattr *tb[], int maxtype,
 370                               const struct nla_policy *policy)
 371 {
 372         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 373                 return -EINVAL;
 374
 375         return nla_parse(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
 376                          nlmsg_attrlen(nlh, hdrlen), policy);
 377 }
 378
 379 /**
 380  * nlmsg_find_attr - find a specific attribute in a netlink message
 381  * @nlh: netlink message header
 382  * @hdrlen: length of familiy specific header
 383  * @attrtype: type of attribute to look for
 384  *
 385  * Returns the first attribute which matches the specified type.
 386  */
 387 static inline struct nlattr *nlmsg_find_attr(struct nlmsghdr *nlh,
 388                                              int hdrlen, int attrtype)
 389 {
 390         return nla_find(nlmsg_attrdata(nlh, hdrlen),
 391                         nlmsg_attrlen(nlh, hdrlen), attrtype);
 392 }
 393
 394 /**
 395  * nlmsg_validate - validate a netlink message including attributes
 396  * @nlh: netlinket message header
 397  * @hdrlen: length of familiy specific header
 398  * @maxtype: maximum attribute type to be expected
 399  * @policy: validation policy
 400  */
 401 static inline int nlmsg_validate(struct nlmsghdr *nlh, int hdrlen, int maxtype,
 402                                  const struct nla_policy *policy)
 403 {
 404         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 405                 return -EINVAL;
 406
 407         return nla_validate(nlmsg_attrdata(nlh, hdrlen),
 408                             nlmsg_attrlen(nlh, hdrlen), maxtype, policy);
 409 }
 410
 411 /**
 412  * nlmsg_report - need to report back to application?
 413  * @nlh: netlink message header
 414  *
 415  * Returns 1 if a report back to the application is requested.
 416  */
 417 static inline int nlmsg_report(const struct nlmsghdr *nlh)
 418 {
 419         return !!(nlh->nlmsg_flags & NLM_F_ECHO);
 420 }
 421
 422 /**
 423  * nlmsg_for_each_attr - iterate over a stream of attributes
 424  * @pos: loop counter, set to current attribute
 425  * @nlh: netlink message header
 426  * @hdrlen: length of familiy specific header
 427  * @rem: initialized to len, holds bytes currently remaining in stream
 428  */
 429 #define nlmsg_for_each_attr(pos, nlh, hdrlen, rem) \
 430         nla_for_each_attr(pos, nlmsg_attrdata(nlh, hdrlen), \
 431                           nlmsg_attrlen(nlh, hdrlen), rem)
 432
 433 #if 0
 434 /* FIXME: Enable once all users have been converted */
 435
 436 /**
 437  * __nlmsg_put - Add a new netlink message to an skb
 438  * @skb: socket buffer to store message in
 439  * @pid: netlink process id
 440  * @seq: sequence number of message
 441  * @type: message type
 442  * @payload: length of message payload
 443  * @flags: message flags
 444  *
 445  * The caller is responsible to ensure that the skb provides enough
 446  * tailroom for both the netlink header and payload.
 447  */
 448 static inline struct nlmsghdr *__nlmsg_put(struct sk_buff *skb, u32 pid,
 449                                            u32 seq, int type, int payload,
 450                                            int flags)
 451 {
 452         struct nlmsghdr *nlh;
 453
 454         nlh = (struct nlmsghdr *) skb_put(skb, nlmsg_total_size(payload));
 455         nlh->nlmsg_type = type;
 456         nlh->nlmsg_len = nlmsg_msg_size(payload);
 457         nlh->nlmsg_flags = flags;
 458         nlh->nlmsg_pid = pid;
 459         nlh->nlmsg_seq = seq;
 460
 461         memset((unsigned char *) nlmsg_data(nlh) + payload, 0,
 462                nlmsg_padlen(payload));
 463
 464         return nlh;
 465 }
 466 #endif
 467
 468 /**
 469  * nlmsg_put - Add a new netlink message to an skb
 470  * @skb: socket buffer to store message in
 471  * @pid: netlink process id
 472  * @seq: sequence number of message
 473  * @type: message type
 474  * @payload: length of message payload
 475  * @flags: message flags
 476  *
 477  * Returns NULL if the tailroom of the skb is insufficient to store
 478  * the message header and payload.
 479  */
 480 static inline struct nlmsghdr *nlmsg_put(struct sk_buff *skb, u32 pid, u32 seq,
 481                                          int type, int payload, int flags)
 482 {
 483         if (unlikely(skb_tailroom(skb) < nlmsg_total_size(payload)))
 484                 return NULL;
 485
 486         return __nlmsg_put(skb, pid, seq, type, payload, flags);
 487 }
 488
 489 /**
 490  * nlmsg_put_answer - Add a new callback based netlink message to an skb
 491  * @skb: socket buffer to store message in
 492  * @cb: netlink callback
 493  * @type: message type
 494  * @payload: length of message payload
 495  * @flags: message flags
 496  *
 497  * Returns NULL if the tailroom of the skb is insufficient to store
 498  * the message header and payload.
 499  */
 500 static inline struct nlmsghdr *nlmsg_put_answer(struct sk_buff *skb,
 501                                                 struct netlink_callback *cb,
 502                                                 int type, int payload,
 503                                                 int flags)
 504 {
 505         return nlmsg_put(skb, NETLINK_CB(cb->skb).pid, cb->nlh->nlmsg_seq,
 506                          type, payload, flags);
 507 }
 508
 509 /**
 510  * nlmsg_new - Allocate a new netlink message
 511  * @payload: size of the message payload
 512  * @flags: the type of memory to allocate.
 513  *
 514  * Use NLMSG_DEFAULT_SIZE if the size of the payload isn't known
 515  * and a good default is needed.
 516  */
 517 static inline struct sk_buff *nlmsg_new(size_t payload, gfp_t flags)
 518 {
 519         return alloc_skb(nlmsg_total_size(payload), flags);
 520 }
 521
 522 /**
 523  * nlmsg_end - Finalize a netlink message
 524  * @skb: socket buffer the message is stored in
 525  * @nlh: netlink message header
 526  *
 527  * Corrects the netlink message header to include the appeneded
 528  * attributes. Only necessary if attributes have been added to
 529  * the message.
 530  *
 531  * Returns the total data length of the skb.
 532  */
 533 static inline int nlmsg_end(struct sk_buff *skb, struct nlmsghdr *nlh)
 534 {
 535         nlh->nlmsg_len = skb_tail_pointer(skb) - (unsigned char *)nlh;
 536
 537         return skb->len;
 538 }
 539
 540 /**
 541  * nlmsg_get_pos - return current position in netlink message
 542  * @skb: socket buffer the message is stored in
 543  *
 544  * Returns a pointer to the current tail of the message.
 545  */
 546 static inline void *nlmsg_get_pos(struct sk_buff *skb)
 547 {
 548         return skb_tail_pointer(skb);
 549 }
 550
 551 /**
 552  * nlmsg_trim - Trim message to a mark
 553  * @skb: socket buffer the message is stored in
 554  * @mark: mark to trim to
 555  *
 556  * Trims the message to the provided mark.
 557  */
 558 static inline void nlmsg_trim(struct sk_buff *skb, const void *mark)
 559 {
 560         if (mark)
 561                 skb_trim(skb, (unsigned char *) mark - skb->data);
 562 }
 563
 564 /**
 565  * nlmsg_cancel - Cancel construction of a netlink message
 566  * @skb: socket buffer the message is stored in
 567  * @nlh: netlink message header
 568  *
 569  * Removes the complete netlink message including all
 570  * attributes from the socket buffer again.
 571  */
 572 static inline void nlmsg_cancel(struct sk_buff *skb, struct nlmsghdr *nlh)
 573 {
 574         nlmsg_trim(skb, nlh);
 575 }
 576
 577 /**
 578  * nlmsg_free - free a netlink message
 579  * @skb: socket buffer of netlink message
 580  */
 581 static inline void nlmsg_free(struct sk_buff *skb)
 582 {
 583         kfree_skb(skb);
 584 }
 585
 586 /**
 587  * nlmsg_multicast - multicast a netlink message
 588  * @sk: netlink socket to spread messages to
 589  * @skb: netlink message as socket buffer
 590  * @pid: own netlink pid to avoid sending to yourself
 591  * @group: multicast group id
 592  * @flags: allocation flags
 593  */
 594 static inline int nlmsg_multicast(struct sock *sk, struct sk_buff *skb,
 595                                   u32 pid, unsigned int group, gfp_t flags)
 596 {
 597         int err;
 598
 599         NETLINK_CB(skb).dst_group = group;
 600
 601         err = netlink_broadcast(sk, skb, pid, group, flags);
 602         if (err > 0)
 603                 err = 0;
 604
 605         return err;
 606 }
 607
 608 /**
 609  * nlmsg_unicast - unicast a netlink message
 610  * @sk: netlink socket to spread message to
 611  * @skb: netlink message as socket buffer
 612  * @pid: netlink pid of the destination socket
 613  */
 614 static inline int nlmsg_unicast(struct sock *sk, struct sk_buff *skb, u32 pid)
 615 {
 616         int err;
 617
 618         err = netlink_unicast(sk, skb, pid, MSG_DONTWAIT);
 619         if (err > 0)
 620                 err = 0;
 621
 622         return err;
 623 }
 624
 625 /**
 626  * nlmsg_for_each_msg - iterate over a stream of messages
 627  * @pos: loop counter, set to current message
 628  * @head: head of message stream
 629  * @len: length of message stream
 630  * @rem: initialized to len, holds bytes currently remaining in stream
 631  */
 632 #define nlmsg_for_each_msg(pos, head, len, rem) \
 633         for (pos = head, rem = len; \
 634              nlmsg_ok(pos, rem); \
 635              pos = nlmsg_next(pos, &(rem)))
 636
 637 /**************************************************************************
 638  * Netlink Attributes
 639  **************************************************************************/
 640
 641 /**
 642  * nla_attr_size - length of attribute not including padding
 643  * @payload: length of payload
 644  */
 645 static 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  */
 654 static 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  */
 663 static 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  */
 672 static 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  */
 681 static 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  */
 690 static 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  */
 700 static 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  */
 715 static 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  */
 730 static inline struct nlattr *nla_find_nested(struct nlattr *nla, int attrtype)
 731 {
 732         return nla_find(nla_data(nla), nla_len(nla), attrtype);
 733 }
 734
 735 /**
 736  * nla_parse_nested - parse nested attributes
 737  * @tb: destination array with maxtype+1 elements
 738  * @maxtype: maximum attribute type to be expected
 739  * @nla: attribute containing the nested attributes
 740  * @policy: validation policy
 741  *
 742  * See nla_parse()
 743  */
 744 static inline int nla_parse_nested(struct nlattr *tb[], int maxtype,
 745                                    const struct nlattr *nla,
 746                                    const struct nla_policy *policy)
 747 {
 748         return nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy);
 749 }
 750
 751 /**
 752  * nla_put_u8 - Add a u8 netlink attribute to a socket buffer
 753  * @skb: socket buffer to add attribute to
 754  * @attrtype: attribute type
 755  * @value: numeric value
 756  */
 757 static inline int nla_put_u8(struct sk_buff *skb, int attrtype, u8 value)
 758 {
 759         return nla_put(skb, attrtype, sizeof(u8), &value);
 760 }
 761
 762 /**
 763  * nla_put_u16 - Add a u16 netlink attribute to a socket buffer
 764  * @skb: socket buffer to add attribute to
 765  * @attrtype: attribute type
 766  * @value: numeric value
 767  */
 768 static inline int nla_put_u16(struct sk_buff *skb, int attrtype, u16 value)
 769 {
 770         return nla_put(skb, attrtype, sizeof(u16), &value);
 771 }
 772
 773 /**
 774  * nla_put_u32 - Add a u32 netlink attribute to a socket buffer
 775  * @skb: socket buffer to add attribute to
 776  * @attrtype: attribute type
 777  * @value: numeric value
 778  */
 779 static inline int nla_put_u32(struct sk_buff *skb, int attrtype, u32 value)
 780 {
 781         return nla_put(skb, attrtype, sizeof(u32), &value);
 782 }
 783
 784 /**
 785  * nla_put_64 - Add a u64 netlink attribute to a socket buffer
 786  * @skb: socket buffer to add attribute to
 787  * @attrtype: attribute type
 788  * @value: numeric value
 789  */
 790 static inline int nla_put_u64(struct sk_buff *skb, int attrtype, u64 value)
 791 {
 792         return nla_put(skb, attrtype, sizeof(u64), &value);
 793 }
 794
 795 /**
 796  * nla_put_string - Add a string netlink attribute to a socket buffer
 797  * @skb: socket buffer to add attribute to
 798  * @attrtype: attribute type
 799  * @str: NUL terminated string
 800  */
 801 static inline int nla_put_string(struct sk_buff *skb, int attrtype,
 802                                  const char *str)
 803 {
 804         return nla_put(skb, attrtype, strlen(str) + 1, str);
 805 }
 806
 807 /**
 808  * nla_put_flag - Add a flag netlink attribute to a socket buffer
 809  * @skb: socket buffer to add attribute to
 810  * @attrtype: attribute type
 811  */
 812 static inline int nla_put_flag(struct sk_buff *skb, int attrtype)
 813 {
 814         return nla_put(skb, attrtype, 0, NULL);
 815 }
 816
 817 /**
 818  * nla_put_msecs - Add a msecs netlink attribute to a socket buffer
 819  * @skb: socket buffer to add attribute to
 820  * @attrtype: attribute type
 821  * @jiffies: number of msecs in jiffies
 822  */
 823 static inline int nla_put_msecs(struct sk_buff *skb, int attrtype,
 824                                 unsigned long jiffies)
 825 {
 826         u64 tmp = jiffies_to_msecs(jiffies);
 827         return nla_put(skb, attrtype, sizeof(u64), &tmp);
 828 }
 829
 830 #define NLA_PUT(skb, attrtype, attrlen, data) \
 831         do { \
 832                 if (unlikely(nla_put(skb, attrtype, attrlen, data) < 0)) \
 833                         goto nla_put_failure; \
 834         } while(0)
 835
 836 #define NLA_PUT_TYPE(skb, type, attrtype, value) \
 837         do { \
 838                 type __tmp = value; \
 839                 NLA_PUT(skb, attrtype, sizeof(type), &__tmp); \
 840         } while(0)
 841
 842 #define NLA_PUT_U8(skb, attrtype, value) \
 843         NLA_PUT_TYPE(skb, u8, attrtype, value)
 844
 845 #define NLA_PUT_U16(skb, attrtype, value) \
 846         NLA_PUT_TYPE(skb, u16, attrtype, value)
 847
 848 #define NLA_PUT_LE16(skb, attrtype, value) \
 849         NLA_PUT_TYPE(skb, __le16, attrtype, value)
 850
 851 #define NLA_PUT_BE16(skb, attrtype, value) \
 852         NLA_PUT_TYPE(skb, __be16, attrtype, value)
 853
 854 #define NLA_PUT_U32(skb, attrtype, value) \
 855         NLA_PUT_TYPE(skb, u32, attrtype, value)
 856
 857 #define NLA_PUT_BE32(skb, attrtype, value) \
 858         NLA_PUT_TYPE(skb, __be32, attrtype, value)
 859
 860 #define NLA_PUT_U64(skb, attrtype, value) \
 861         NLA_PUT_TYPE(skb, u64, attrtype, value)
 862
 863 #define NLA_PUT_BE64(skb, attrtype, value) \
 864         NLA_PUT_TYPE(skb, __be64, attrtype, value)
 865
 866 #define NLA_PUT_STRING(skb, attrtype, value) \
 867         NLA_PUT(skb, attrtype, strlen(value) + 1, value)
 868
 869 #define NLA_PUT_FLAG(skb, attrtype) \
 870         NLA_PUT(skb, attrtype, 0, NULL)
 871
 872 #define NLA_PUT_MSECS(skb, attrtype, jiffies) \
 873         NLA_PUT_U64(skb, attrtype, jiffies_to_msecs(jiffies))
 874
 875 /**
 876  * nla_get_u32 - return payload of u32 attribute
 877  * @nla: u32 netlink attribute
 878  */
 879 static inline u32 nla_get_u32(const struct nlattr *nla)
 880 {
 881         return *(u32 *) nla_data(nla);
 882 }
 883
 884 /**
 885  * nla_get_be32 - return payload of __be32 attribute
 886  * @nla: __be32 netlink attribute
 887  */
 888 static inline __be32 nla_get_be32(const struct nlattr *nla)
 889 {
 890         return *(__be32 *) nla_data(nla);
 891 }
 892
 893 /**
 894  * nla_get_u16 - return payload of u16 attribute
 895  * @nla: u16 netlink attribute
 896  */
 897 static inline u16 nla_get_u16(const struct nlattr *nla)
 898 {
 899         return *(u16 *) nla_data(nla);
 900 }
 901
 902 /**
 903  * nla_get_be16 - return payload of __be16 attribute
 904  * @nla: __be16 netlink attribute
 905  */
 906 static inline __be16 nla_get_be16(const struct nlattr *nla)
 907 {
 908         return *(__be16 *) nla_data(nla);
 909 }
 910
 911 /**
 912  * nla_get_le16 - return payload of __le16 attribute
 913  * @nla: __le16 netlink attribute
 914  */
 915 static inline __le16 nla_get_le16(const struct nlattr *nla)
 916 {
 917         return *(__le16 *) nla_data(nla);
 918 }
 919
 920 /**
 921  * nla_get_u8 - return payload of u8 attribute
 922  * @nla: u8 netlink attribute
 923  */
 924 static inline u8 nla_get_u8(const struct nlattr *nla)
 925 {
 926         return *(u8 *) nla_data(nla);
 927 }
 928
 929 /**
 930  * nla_get_u64 - return payload of u64 attribute
 931  * @nla: u64 netlink attribute
 932  */
 933 static inline u64 nla_get_u64(const struct nlattr *nla)
 934 {
 935         u64 tmp;
 936
 937         nla_memcpy(&tmp, nla, sizeof(tmp));
 938
 939         return tmp;
 940 }
 941
 942 /**
 943  * nla_get_be64 - return payload of __be64 attribute
 944  * @nla: __be64 netlink attribute
 945  */
 946 static inline __be64 nla_get_be64(const struct nlattr *nla)
 947 {
 948         return *(__be64 *) nla_data(nla);
 949 }
 950
 951 /**
 952  * nla_get_flag - return payload of flag attribute
 953  * @nla: flag netlink attribute
 954  */
 955 static inline int nla_get_flag(const struct nlattr *nla)
 956 {
 957         return !!nla;
 958 }
 959
 960 /**
 961  * nla_get_msecs - return payload of msecs attribute
 962  * @nla: msecs netlink attribute
 963  *
 964  * Returns the number of milliseconds in jiffies.
 965  */
 966 static inline unsigned long nla_get_msecs(const struct nlattr *nla)
 967 {
 968         u64 msecs = nla_get_u64(nla);
 969
 970         return msecs_to_jiffies((unsigned long) msecs);
 971 }
 972
 973 /**
 974  * nla_nest_start - Start a new level of nested attributes
 975  * @skb: socket buffer to add attributes to
 976  * @attrtype: attribute type of container
 977  *
 978  * Returns the container attribute
 979  */
 980 static inline struct nlattr *nla_nest_start(struct sk_buff *skb, int attrtype)
 981 {
 982         struct nlattr *start = (struct nlattr *)skb_tail_pointer(skb);
 983
 984         if (nla_put(skb, attrtype, 0, NULL) < 0)
 985                 return NULL;
 986
 987         return start;
 988 }
 989
 990 /**
 991  * nla_nest_end - Finalize nesting of attributes
 992  * @skb: socket buffer the attributes are stored in
 993  * @start: container attribute
 994  *
 995  * Corrects the container attribute header to include the all
 996  * appeneded attributes.
 997  *
 998  * Returns the total data length of the skb.
 999  */
1000 static inline int nla_nest_end(struct sk_buff *skb, struct nlattr *start)
1001 {
1002         start->nla_len = skb_tail_pointer(skb) - (unsigned char *)start;
1003         return skb->len;
1004 }
1005
1006 /**
1007  * nla_nest_cancel - Cancel nesting of attributes
1008  * @skb: socket buffer the message is stored in
1009  * @start: container attribute
1010  *
1011  * Removes the container attribute and including all nested
1012  * attributes. Returns -EMSGSIZE
1013  */
1014 static inline void nla_nest_cancel(struct sk_buff *skb, struct nlattr *start)
1015 {
1016         nlmsg_trim(skb, start);
1017 }
1018
1019 /**
1020  * nla_validate_nested - Validate a stream of nested attributes
1021  * @start: container attribute
1022  * @maxtype: maximum attribute type to be expected
1023  * @policy: validation policy
1024  *
1025  * Validates all attributes in the nested attribute stream against the
1026  * specified policy. Attributes with a type exceeding maxtype will be
1027  * ignored. See documenation of struct nla_policy for more details.
1028  *
1029  * Returns 0 on success or a negative error code.
1030  */
1031 static inline int nla_validate_nested(struct nlattr *start, int maxtype,
1032                                       const struct nla_policy *policy)
1033 {
1034         return nla_validate(nla_data(start), nla_len(start), maxtype, policy);
1035 }
1036
1037 /**
1038  * nla_for_each_attr - iterate over a stream of attributes
1039  * @pos: loop counter, set to current attribute
1040  * @head: head of attribute stream
1041  * @len: length of attribute stream
1042  * @rem: initialized to len, holds bytes currently remaining in stream
1043  */
1044 #define nla_for_each_attr(pos, head, len, rem) \
1045         for (pos = head, rem = len; \
1046              nla_ok(pos, rem); \
1047              pos = nla_next(pos, &(rem)))
1048
1049 /**
1050  * nla_for_each_nested - iterate over nested attributes
1051  * @pos: loop counter, set to current attribute
1052  * @nla: attribute containing the nested attributes
1053  * @rem: initialized to len, holds bytes currently remaining in stream
1054  */
1055 #define nla_for_each_nested(pos, nla, rem) \
1056         nla_for_each_attr(pos, nla_data(nla), nla_len(nla), rem)
1057
1058 #endif