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  * 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 const struct nla_policy my_policy[ATTR_MAX+1] = {
 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(const struct nlattr *head,
 229                                      int len, int maxtype,
 230                                      const struct nla_policy *policy);
 231 extern int              nla_parse(struct nlattr **tb, int maxtype,
 232                                   const struct nlattr *head, int len,
 233                                   const struct nla_policy *policy);
 234 extern int              nla_policy_len(const struct nla_policy *, int);
 235 extern struct nlattr *  nla_find(const struct nlattr *head,
 236                                  int len, int attrtype);
 237 extern size_t           nla_strlcpy(char *dst, const struct nlattr *nla,
 238                                     size_t dstsize);
 239 extern int              nla_memcpy(void *dest, const struct nlattr *src, int count);
 240 extern int              nla_memcmp(const struct nlattr *nla, const void *data,
 241                                    size_t size);
 242 extern int              nla_strcmp(const struct nlattr *nla, const char *str);
 243 extern struct nlattr *  __nla_reserve(struct sk_buff *skb, int attrtype,
 244                                       int attrlen);
 245 extern void *           __nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
 246 extern struct nlattr *  nla_reserve(struct sk_buff *skb, int attrtype,
 247                                     int attrlen);
 248 extern void *           nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
 249 extern void             __nla_put(struct sk_buff *skb, int attrtype,
 250                                   int attrlen, const void *data);
 251 extern void             __nla_put_nohdr(struct sk_buff *skb, int attrlen,
 252                                         const void *data);
 253 extern int              nla_put(struct sk_buff *skb, int attrtype,
 254                                 int attrlen, const void *data);
 255 extern int              nla_put_nohdr(struct sk_buff *skb, int attrlen,
 256                                       const void *data);
 257 extern int              nla_append(struct sk_buff *skb, int attrlen,
 258                                    const void *data);
 259
 260 /**************************************************************************
 261  * Netlink Messages
 262  **************************************************************************/
 263
 264 /**
 265  * nlmsg_msg_size - length of netlink message not including padding
 266  * @payload: length of message payload
 267  */
 268 static inline int nlmsg_msg_size(int payload)
 269 {
 270         return NLMSG_HDRLEN + payload;
 271 }
 272
 273 /**
 274  * nlmsg_total_size - length of netlink message including padding
 275  * @payload: length of message payload
 276  */
 277 static inline int nlmsg_total_size(int payload)
 278 {
 279         return NLMSG_ALIGN(nlmsg_msg_size(payload));
 280 }
 281
 282 /**
 283  * nlmsg_padlen - length of padding at the message's tail
 284  * @payload: length of message payload
 285  */
 286 static inline int nlmsg_padlen(int payload)
 287 {
 288         return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
 289 }
 290
 291 /**
 292  * nlmsg_data - head of message payload
 293  * @nlh: netlink message header
 294  */
 295 static inline void *nlmsg_data(const struct nlmsghdr *nlh)
 296 {
 297         return (unsigned char *) nlh + NLMSG_HDRLEN;
 298 }
 299
 300 /**
 301  * nlmsg_len - length of message payload
 302  * @nlh: netlink message header
 303  */
 304 static inline int nlmsg_len(const struct nlmsghdr *nlh)
 305 {
 306         return nlh->nlmsg_len - NLMSG_HDRLEN;
 307 }
 308
 309 /**
 310  * nlmsg_attrdata - head of attributes data
 311  * @nlh: netlink message header
 312  * @hdrlen: length of family specific header
 313  */
 314 static inline struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh,
 315                                             int hdrlen)
 316 {
 317         unsigned char *data = nlmsg_data(nlh);
 318         return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
 319 }
 320
 321 /**
 322  * nlmsg_attrlen - length of attributes data
 323  * @nlh: netlink message header
 324  * @hdrlen: length of family specific header
 325  */
 326 static inline int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
 327 {
 328         return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);
 329 }
 330
 331 /**
 332  * nlmsg_ok - check if the netlink message fits into the remaining bytes
 333  * @nlh: netlink message header
 334  * @remaining: number of bytes remaining in message stream
 335  */
 336 static inline int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
 337 {
 338         return (remaining >= (int) sizeof(struct nlmsghdr) &&
 339                 nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
 340                 nlh->nlmsg_len <= remaining);
 341 }
 342
 343 /**
 344  * nlmsg_next - next netlink message in message stream
 345  * @nlh: netlink message header
 346  * @remaining: number of bytes remaining in message stream
 347  *
 348  * Returns the next netlink message in the message stream and
 349  * decrements remaining by the size of the current message.
 350  */
 351 static inline struct nlmsghdr *
 352 nlmsg_next(const struct nlmsghdr *nlh, int *remaining)
 353 {
 354         int totlen = NLMSG_ALIGN(nlh->nlmsg_len);
 355
 356         *remaining -= totlen;
 357
 358         return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
 359 }
 360
 361 /**
 362  * nlmsg_parse - parse attributes of a netlink message
 363  * @nlh: netlink message header
 364  * @hdrlen: length of family specific header
 365  * @tb: destination array with maxtype+1 elements
 366  * @maxtype: maximum attribute type to be expected
 367  * @policy: validation policy
 368  *
 369  * See nla_parse()
 370  */
 371 static inline int nlmsg_parse(const struct nlmsghdr *nlh, int hdrlen,
 372                               struct nlattr *tb[], int maxtype,
 373                               const struct nla_policy *policy)
 374 {
 375         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 376                 return -EINVAL;
 377
 378         return nla_parse(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
 379                          nlmsg_attrlen(nlh, hdrlen), policy);
 380 }
 381
 382 /**
 383  * nlmsg_find_attr - find a specific attribute in a netlink message
 384  * @nlh: netlink message header
 385  * @hdrlen: length of familiy specific header
 386  * @attrtype: type of attribute to look for
 387  *
 388  * Returns the first attribute which matches the specified type.
 389  */
 390 static inline struct nlattr *nlmsg_find_attr(const struct nlmsghdr *nlh,
 391                                              int hdrlen, int attrtype)
 392 {
 393         return nla_find(nlmsg_attrdata(nlh, hdrlen),
 394                         nlmsg_attrlen(nlh, hdrlen), attrtype);
 395 }
 396
 397 /**
 398  * nlmsg_validate - validate a netlink message including attributes
 399  * @nlh: netlinket message header
 400  * @hdrlen: length of familiy specific header
 401  * @maxtype: maximum attribute type to be expected
 402  * @policy: validation policy
 403  */
 404 static inline int nlmsg_validate(const struct nlmsghdr *nlh,
 405                                  int hdrlen, int maxtype,
 406                                  const struct nla_policy *policy)
 407 {
 408         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 409                 return -EINVAL;
 410
 411         return nla_validate(nlmsg_attrdata(nlh, hdrlen),
 412                             nlmsg_attrlen(nlh, hdrlen), maxtype, policy);
 413 }
 414
 415 /**
 416  * nlmsg_report - need to report back to application?
 417  * @nlh: netlink message header
 418  *
 419  * Returns 1 if a report back to the application is requested.
 420  */
 421 static inline int nlmsg_report(const struct nlmsghdr *nlh)
 422 {
 423         return !!(nlh->nlmsg_flags & NLM_F_ECHO);
 424 }
 425
 426 /**
 427  * nlmsg_for_each_attr - iterate over a stream of attributes
 428  * @pos: loop counter, set to current attribute
 429  * @nlh: netlink message header
 430  * @hdrlen: length of familiy specific header
 431  * @rem: initialized to len, holds bytes currently remaining in stream
 432  */
 433 #define nlmsg_for_each_attr(pos, nlh, hdrlen, rem) \
 434         nla_for_each_attr(pos, nlmsg_attrdata(nlh, hdrlen), \
 435                           nlmsg_attrlen(nlh, hdrlen), rem)
 436
 437 #if 0
 438 /* FIXME: Enable once all users have been converted */
 439
 440 /**
 441  * __nlmsg_put - Add a new netlink message to an skb
 442  * @skb: socket buffer to store message in
 443  * @pid: netlink process id
 444  * @seq: sequence number of message
 445  * @type: message type
 446  * @payload: length of message payload
 447  * @flags: message flags
 448  *
 449  * The caller is responsible to ensure that the skb provides enough
 450  * tailroom for both the netlink header and payload.
 451  */
 452 static inline struct nlmsghdr *__nlmsg_put(struct sk_buff *skb, u32 pid,
 453                                            u32 seq, int type, int payload,
 454                                            int flags)
 455 {
 456         struct nlmsghdr *nlh;
 457
 458         nlh = (struct nlmsghdr *) skb_put(skb, nlmsg_total_size(payload));
 459         nlh->nlmsg_type = type;
 460         nlh->nlmsg_len = nlmsg_msg_size(payload);
 461         nlh->nlmsg_flags = flags;
 462         nlh->nlmsg_pid = pid;
 463         nlh->nlmsg_seq = seq;
 464
 465         memset((unsigned char *) nlmsg_data(nlh) + payload, 0,
 466                nlmsg_padlen(payload));
 467
 468         return nlh;
 469 }
 470 #endif
 471
 472 /**
 473  * nlmsg_put - Add a new netlink message to an skb
 474  * @skb: socket buffer to store message in
 475  * @pid: netlink process id
 476  * @seq: sequence number of message
 477  * @type: message type
 478  * @payload: length of message payload
 479  * @flags: message flags
 480  *
 481  * Returns NULL if the tailroom of the skb is insufficient to store
 482  * the message header and payload.
 483  */
 484 static inline struct nlmsghdr *nlmsg_put(struct sk_buff *skb, u32 pid, u32 seq,
 485                                          int type, int payload, int flags)
 486 {
 487         if (unlikely(skb_tailroom(skb) < nlmsg_total_size(payload)))
 488                 return NULL;
 489
 490         return __nlmsg_put(skb, pid, seq, type, payload, flags);
 491 }
 492
 493 /**
 494  * nlmsg_put_answer - Add a new callback based netlink message to an skb
 495  * @skb: socket buffer to store message in
 496  * @cb: netlink callback
 497  * @type: message type
 498  * @payload: length of message payload
 499  * @flags: message flags
 500  *
 501  * Returns NULL if the tailroom of the skb is insufficient to store
 502  * the message header and payload.
 503  */
 504 static inline struct nlmsghdr *nlmsg_put_answer(struct sk_buff *skb,
 505                                                 struct netlink_callback *cb,
 506                                                 int type, int payload,
 507                                                 int flags)
 508 {
 509         return nlmsg_put(skb, NETLINK_CB(cb->skb).pid, cb->nlh->nlmsg_seq,
 510                          type, payload, flags);
 511 }
 512
 513 /**
 514  * nlmsg_new - Allocate a new netlink message
 515  * @payload: size of the message payload
 516  * @flags: the type of memory to allocate.
 517  *
 518  * Use NLMSG_DEFAULT_SIZE if the size of the payload isn't known
 519  * and a good default is needed.
 520  */
 521 static inline struct sk_buff *nlmsg_new(size_t payload, gfp_t flags)
 522 {
 523         return alloc_skb(nlmsg_total_size(payload), flags);
 524 }
 525
 526 /**
 527  * nlmsg_end - Finalize a netlink message
 528  * @skb: socket buffer the message is stored in
 529  * @nlh: netlink message header
 530  *
 531  * Corrects the netlink message header to include the appeneded
 532  * attributes. Only necessary if attributes have been added to
 533  * the message.
 534  *
 535  * Returns the total data length of the skb.
 536  */
 537 static inline int nlmsg_end(struct sk_buff *skb, struct nlmsghdr *nlh)
 538 {
 539         nlh->nlmsg_len = skb_tail_pointer(skb) - (unsigned char *)nlh;
 540
 541         return skb->len;
 542 }
 543
 544 /**
 545  * nlmsg_get_pos - return current position in netlink message
 546  * @skb: socket buffer the message is stored in
 547  *
 548  * Returns a pointer to the current tail of the message.
 549  */
 550 static inline void *nlmsg_get_pos(struct sk_buff *skb)
 551 {
 552         return skb_tail_pointer(skb);
 553 }
 554
 555 /**
 556  * nlmsg_trim - Trim message to a mark
 557  * @skb: socket buffer the message is stored in
 558  * @mark: mark to trim to
 559  *
 560  * Trims the message to the provided mark.
 561  */
 562 static inline void nlmsg_trim(struct sk_buff *skb, const void *mark)
 563 {
 564         if (mark)
 565                 skb_trim(skb, (unsigned char *) mark - skb->data);
 566 }
 567
 568 /**
 569  * nlmsg_cancel - Cancel construction of a netlink message
 570  * @skb: socket buffer the message is stored in
 571  * @nlh: netlink message header
 572  *
 573  * Removes the complete netlink message including all
 574  * attributes from the socket buffer again.
 575  */
 576 static inline void nlmsg_cancel(struct sk_buff *skb, struct nlmsghdr *nlh)
 577 {
 578         nlmsg_trim(skb, nlh);
 579 }
 580
 581 /**
 582  * nlmsg_free - free a netlink message
 583  * @skb: socket buffer of netlink message
 584  */
 585 static inline void nlmsg_free(struct sk_buff *skb)
 586 {
 587         kfree_skb(skb);
 588 }
 589
 590 /**
 591  * nlmsg_multicast - multicast a netlink message
 592  * @sk: netlink socket to spread messages to
 593  * @skb: netlink message as socket buffer
 594  * @pid: own netlink pid to avoid sending to yourself
 595  * @group: multicast group id
 596  * @flags: allocation flags
 597  */
 598 static inline int nlmsg_multicast(struct sock *sk, struct sk_buff *skb,
 599                                   u32 pid, unsigned int group, gfp_t flags)
 600 {
 601         int err;
 602
 603         NETLINK_CB(skb).dst_group = group;
 604
 605         err = netlink_broadcast(sk, skb, pid, group, flags);
 606         if (err > 0)
 607                 err = 0;
 608
 609         return err;
 610 }
 611
 612 /**
 613  * nlmsg_unicast - unicast a netlink message
 614  * @sk: netlink socket to spread message to
 615  * @skb: netlink message as socket buffer
 616  * @pid: netlink pid of the destination socket
 617  */
 618 static inline int nlmsg_unicast(struct sock *sk, struct sk_buff *skb, u32 pid)
 619 {
 620         int err;
 621
 622         err = netlink_unicast(sk, skb, pid, MSG_DONTWAIT);
 623         if (err > 0)
 624                 err = 0;
 625
 626         return err;
 627 }
 628
 629 /**
 630  * nlmsg_for_each_msg - iterate over a stream of messages
 631  * @pos: loop counter, set to current message
 632  * @head: head of message stream
 633  * @len: length of message stream
 634  * @rem: initialized to len, holds bytes currently remaining in stream
 635  */
 636 #define nlmsg_for_each_msg(pos, head, len, rem) \
 637         for (pos = head, rem = len; \
 638              nlmsg_ok(pos, rem); \
 639              pos = nlmsg_next(pos, &(rem)))
 640
 641 /**
 642  * nl_dump_check_consistent - check if sequence is consistent and advertise if not
 643  * @cb: netlink callback structure that stores the sequence number
 644  * @nlh: netlink message header to write the flag to
 645  *
 646  * This function checks if the sequence (generation) number changed during dump
 647  * and if it did, advertises it in the netlink message header.
 648  *
 649  * The correct way to use it is to set cb->seq to the generation counter when
 650  * all locks for dumping have been acquired, and then call this function for
 651  * each message that is generated.
 652  *
 653  * Note that due to initialisation concerns, 0 is an invalid sequence number
 654  * and must not be used by code that uses this functionality.
 655  */
 656 static inline void
 657 nl_dump_check_consistent(struct netlink_callback *cb,
 658                          struct nlmsghdr *nlh)
 659 {
 660         if (cb->prev_seq && cb->seq != cb->prev_seq)
 661                 nlh->nlmsg_flags |= NLM_F_DUMP_INTR;
 662         cb->prev_seq = cb->seq;
 663 }
 664
 665 /**************************************************************************
 666  * Netlink Attributes
 667  **************************************************************************/
 668
 669 /**
 670  * nla_attr_size - length of attribute not including padding
 671  * @payload: length of payload
 672  */
 673 static inline int nla_attr_size(int payload)
 674 {
 675         return NLA_HDRLEN + payload;
 676 }
 677
 678 /**
 679  * nla_total_size - total length of attribute including padding
 680  * @payload: length of payload
 681  */
 682 static inline int nla_total_size(int payload)
 683 {
 684         return NLA_ALIGN(nla_attr_size(payload));
 685 }
 686
 687 /**
 688  * nla_padlen - length of padding at the tail of attribute
 689  * @payload: length of payload
 690  */
 691 static inline int nla_padlen(int payload)
 692 {
 693         return nla_total_size(payload) - nla_attr_size(payload);
 694 }
 695
 696 /**
 697  * nla_type - attribute type
 698  * @nla: netlink attribute
 699  */
 700 static inline int nla_type(const struct nlattr *nla)
 701 {
 702         return nla->nla_type & NLA_TYPE_MASK;
 703 }
 704
 705 /**
 706  * nla_data - head of payload
 707  * @nla: netlink attribute
 708  */
 709 static inline void *nla_data(const struct nlattr *nla)
 710 {
 711         return (char *) nla + NLA_HDRLEN;
 712 }
 713
 714 /**
 715  * nla_len - length of payload
 716  * @nla: netlink attribute
 717  */
 718 static inline int nla_len(const struct nlattr *nla)
 719 {
 720         return nla->nla_len - NLA_HDRLEN;
 721 }
 722
 723 /**
 724  * nla_ok - check if the netlink attribute fits into the remaining bytes
 725  * @nla: netlink attribute
 726  * @remaining: number of bytes remaining in attribute stream
 727  */
 728 static inline int nla_ok(const struct nlattr *nla, int remaining)
 729 {
 730         return remaining >= (int) sizeof(*nla) &&
 731                nla->nla_len >= sizeof(*nla) &&
 732                nla->nla_len <= remaining;
 733 }
 734
 735 /**
 736  * nla_next - next netlink attribute in attribute stream
 737  * @nla: netlink attribute
 738  * @remaining: number of bytes remaining in attribute stream
 739  *
 740  * Returns the next netlink attribute in the attribute stream and
 741  * decrements remaining by the size of the current attribute.
 742  */
 743 static inline struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
 744 {
 745         int totlen = NLA_ALIGN(nla->nla_len);
 746
 747         *remaining -= totlen;
 748         return (struct nlattr *) ((char *) nla + totlen);
 749 }
 750
 751 /**
 752  * nla_find_nested - find attribute in a set of nested attributes
 753  * @nla: attribute containing the nested attributes
 754  * @attrtype: type of attribute to look for
 755  *
 756  * Returns the first attribute which matches the specified type.
 757  */
 758 static inline struct nlattr *
 759 nla_find_nested(const struct nlattr *nla, int attrtype)
 760 {
 761         return nla_find(nla_data(nla), nla_len(nla), attrtype);
 762 }
 763
 764 /**
 765  * nla_parse_nested - parse nested attributes
 766  * @tb: destination array with maxtype+1 elements
 767  * @maxtype: maximum attribute type to be expected
 768  * @nla: attribute containing the nested attributes
 769  * @policy: validation policy
 770  *
 771  * See nla_parse()
 772  */
 773 static inline int nla_parse_nested(struct nlattr *tb[], int maxtype,
 774                                    const struct nlattr *nla,
 775                                    const struct nla_policy *policy)
 776 {
 777         return nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy);
 778 }
 779
 780 /**
 781  * nla_put_u8 - Add a u8 netlink attribute to a socket buffer
 782  * @skb: socket buffer to add attribute to
 783  * @attrtype: attribute type
 784  * @value: numeric value
 785  */
 786 static inline int nla_put_u8(struct sk_buff *skb, int attrtype, u8 value)
 787 {
 788         return nla_put(skb, attrtype, sizeof(u8), &value);
 789 }
 790
 791 /**
 792  * nla_put_u16 - Add a u16 netlink attribute to a socket buffer
 793  * @skb: socket buffer to add attribute to
 794  * @attrtype: attribute type
 795  * @value: numeric value
 796  */
 797 static inline int nla_put_u16(struct sk_buff *skb, int attrtype, u16 value)
 798 {
 799         return nla_put(skb, attrtype, sizeof(u16), &value);
 800 }
 801
 802 /**
 803  * nla_put_u32 - Add a u32 netlink attribute to a socket buffer
 804  * @skb: socket buffer to add attribute to
 805  * @attrtype: attribute type
 806  * @value: numeric value
 807  */
 808 static inline int nla_put_u32(struct sk_buff *skb, int attrtype, u32 value)
 809 {
 810         return nla_put(skb, attrtype, sizeof(u32), &value);
 811 }
 812
 813 /**
 814  * nla_put_64 - Add a u64 netlink attribute to a socket buffer
 815  * @skb: socket buffer to add attribute to
 816  * @attrtype: attribute type
 817  * @value: numeric value
 818  */
 819 static inline int nla_put_u64(struct sk_buff *skb, int attrtype, u64 value)
 820 {
 821         return nla_put(skb, attrtype, sizeof(u64), &value);
 822 }
 823
 824 /**
 825  * nla_put_string - Add a string netlink attribute to a socket buffer
 826  * @skb: socket buffer to add attribute to
 827  * @attrtype: attribute type
 828  * @str: NUL terminated string
 829  */
 830 static inline int nla_put_string(struct sk_buff *skb, int attrtype,
 831                                  const char *str)
 832 {
 833         return nla_put(skb, attrtype, strlen(str) + 1, str);
 834 }
 835
 836 /**
 837  * nla_put_flag - Add a flag netlink attribute to a socket buffer
 838  * @skb: socket buffer to add attribute to
 839  * @attrtype: attribute type
 840  */
 841 static inline int nla_put_flag(struct sk_buff *skb, int attrtype)
 842 {
 843         return nla_put(skb, attrtype, 0, NULL);
 844 }
 845
 846 /**
 847  * nla_put_msecs - Add a msecs netlink attribute to a socket buffer
 848  * @skb: socket buffer to add attribute to
 849  * @attrtype: attribute type
 850  * @jiffies: number of msecs in jiffies
 851  */
 852 static inline int nla_put_msecs(struct sk_buff *skb, int attrtype,
 853                                 unsigned long jiffies)
 854 {
 855         u64 tmp = jiffies_to_msecs(jiffies);
 856         return nla_put(skb, attrtype, sizeof(u64), &tmp);
 857 }
 858
 859 #define NLA_PUT(skb, attrtype, attrlen, data) \
 860         do { \
 861                 if (unlikely(nla_put(skb, attrtype, attrlen, data) < 0)) \
 862                         goto nla_put_failure; \
 863         } while(0)
 864
 865 #define NLA_PUT_TYPE(skb, type, attrtype, value) \
 866         do { \
 867                 type __tmp = value; \
 868                 NLA_PUT(skb, attrtype, sizeof(type), &__tmp); \
 869         } while(0)
 870
 871 #define NLA_PUT_U8(skb, attrtype, value) \
 872         NLA_PUT_TYPE(skb, u8, attrtype, value)
 873
 874 #define NLA_PUT_U16(skb, attrtype, value) \
 875         NLA_PUT_TYPE(skb, u16, attrtype, value)
 876
 877 #define NLA_PUT_LE16(skb, attrtype, value) \
 878         NLA_PUT_TYPE(skb, __le16, attrtype, value)
 879
 880 #define NLA_PUT_BE16(skb, attrtype, value) \
 881         NLA_PUT_TYPE(skb, __be16, attrtype, value)
 882
 883 #define NLA_PUT_NET16(skb, attrtype, value) \
 884         NLA_PUT_BE16(skb, attrtype | NLA_F_NET_BYTEORDER, value)
 885
 886 #define NLA_PUT_U32(skb, attrtype, value) \
 887         NLA_PUT_TYPE(skb, u32, attrtype, value)
 888
 889 #define NLA_PUT_BE32(skb, attrtype, value) \
 890         NLA_PUT_TYPE(skb, __be32, attrtype, value)
 891
 892 #define NLA_PUT_NET32(skb, attrtype, value) \
 893         NLA_PUT_BE32(skb, attrtype | NLA_F_NET_BYTEORDER, value)
 894
 895 #define NLA_PUT_U64(skb, attrtype, value) \
 896         NLA_PUT_TYPE(skb, u64, attrtype, value)
 897
 898 #define NLA_PUT_BE64(skb, attrtype, value) \
 899         NLA_PUT_TYPE(skb, __be64, attrtype, value)
 900
 901 #define NLA_PUT_NET64(skb, attrtype, value) \
 902         NLA_PUT_BE64(skb, attrtype | NLA_F_NET_BYTEORDER, value)
 903
 904 #define NLA_PUT_STRING(skb, attrtype, value) \
 905         NLA_PUT(skb, attrtype, strlen(value) + 1, value)
 906
 907 #define NLA_PUT_FLAG(skb, attrtype) \
 908         NLA_PUT(skb, attrtype, 0, NULL)
 909
 910 #define NLA_PUT_MSECS(skb, attrtype, jiffies) \
 911         NLA_PUT_U64(skb, attrtype, jiffies_to_msecs(jiffies))
 912
 913 /**
 914  * nla_get_u32 - return payload of u32 attribute
 915  * @nla: u32 netlink attribute
 916  */
 917 static inline u32 nla_get_u32(const struct nlattr *nla)
 918 {
 919         return *(u32 *) nla_data(nla);
 920 }
 921
 922 /**
 923  * nla_get_be32 - return payload of __be32 attribute
 924  * @nla: __be32 netlink attribute
 925  */
 926 static inline __be32 nla_get_be32(const struct nlattr *nla)
 927 {
 928         return *(__be32 *) nla_data(nla);
 929 }
 930
 931 /**
 932  * nla_get_u16 - return payload of u16 attribute
 933  * @nla: u16 netlink attribute
 934  */
 935 static inline u16 nla_get_u16(const struct nlattr *nla)
 936 {
 937         return *(u16 *) nla_data(nla);
 938 }
 939
 940 /**
 941  * nla_get_be16 - return payload of __be16 attribute
 942  * @nla: __be16 netlink attribute
 943  */
 944 static inline __be16 nla_get_be16(const struct nlattr *nla)
 945 {
 946         return *(__be16 *) nla_data(nla);
 947 }
 948
 949 /**
 950  * nla_get_le16 - return payload of __le16 attribute
 951  * @nla: __le16 netlink attribute
 952  */
 953 static inline __le16 nla_get_le16(const struct nlattr *nla)
 954 {
 955         return *(__le16 *) nla_data(nla);
 956 }
 957
 958 /**
 959  * nla_get_u8 - return payload of u8 attribute
 960  * @nla: u8 netlink attribute
 961  */
 962 static inline u8 nla_get_u8(const struct nlattr *nla)
 963 {
 964         return *(u8 *) nla_data(nla);
 965 }
 966
 967 /**
 968  * nla_get_u64 - return payload of u64 attribute
 969  * @nla: u64 netlink attribute
 970  */
 971 static inline u64 nla_get_u64(const struct nlattr *nla)
 972 {
 973         u64 tmp;
 974
 975         nla_memcpy(&tmp, nla, sizeof(tmp));
 976
 977         return tmp;
 978 }
 979
 980 /**
 981  * nla_get_be64 - return payload of __be64 attribute
 982  * @nla: __be64 netlink attribute
 983  */
 984 static inline __be64 nla_get_be64(const struct nlattr *nla)
 985 {
 986         __be64 tmp;
 987
 988         nla_memcpy(&tmp, nla, sizeof(tmp));
 989
 990         return tmp;
 991 }
 992
 993 /**
 994  * nla_get_flag - return payload of flag attribute
 995  * @nla: flag netlink attribute
 996  */
 997 static inline int nla_get_flag(const struct nlattr *nla)
 998 {
 999         return !!nla;
1000 }
1001
1002 /**
1003  * nla_get_msecs - return payload of msecs attribute
1004  * @nla: msecs netlink attribute
1005  *
1006  * Returns the number of milliseconds in jiffies.
1007  */
1008 static inline unsigned long nla_get_msecs(const struct nlattr *nla)
1009 {
1010         u64 msecs = nla_get_u64(nla);
1011
1012         return msecs_to_jiffies((unsigned long) msecs);
1013 }
1014
1015 /**
1016  * nla_nest_start - Start a new level of nested attributes
1017  * @skb: socket buffer to add attributes to
1018  * @attrtype: attribute type of container
1019  *
1020  * Returns the container attribute
1021  */
1022 static inline struct nlattr *nla_nest_start(struct sk_buff *skb, int attrtype)
1023 {
1024         struct nlattr *start = (struct nlattr *)skb_tail_pointer(skb);
1025
1026         if (nla_put(skb, attrtype, 0, NULL) < 0)
1027                 return NULL;
1028
1029         return start;
1030 }
1031
1032 /**
1033  * nla_nest_end - Finalize nesting of attributes
1034  * @skb: socket buffer the attributes are stored in
1035  * @start: container attribute
1036  *
1037  * Corrects the container attribute header to include the all
1038  * appeneded attributes.
1039  *
1040  * Returns the total data length of the skb.
1041  */
1042 static inline int nla_nest_end(struct sk_buff *skb, struct nlattr *start)
1043 {
1044         start->nla_len = skb_tail_pointer(skb) - (unsigned char *)start;
1045         return skb->len;
1046 }
1047
1048 /**
1049  * nla_nest_cancel - Cancel nesting of attributes
1050  * @skb: socket buffer the message is stored in
1051  * @start: container attribute
1052  *
1053  * Removes the container attribute and including all nested
1054  * attributes. Returns -EMSGSIZE
1055  */
1056 static inline void nla_nest_cancel(struct sk_buff *skb, struct nlattr *start)
1057 {
1058         nlmsg_trim(skb, start);
1059 }
1060
1061 /**
1062  * nla_validate_nested - Validate a stream of nested attributes
1063  * @start: container attribute
1064  * @maxtype: maximum attribute type to be expected
1065  * @policy: validation policy
1066  *
1067  * Validates all attributes in the nested attribute stream against the
1068  * specified policy. Attributes with a type exceeding maxtype will be
1069  * ignored. See documenation of struct nla_policy for more details.
1070  *
1071  * Returns 0 on success or a negative error code.
1072  */
1073 static inline int nla_validate_nested(const struct nlattr *start, int maxtype,
1074                                       const struct nla_policy *policy)
1075 {
1076         return nla_validate(nla_data(start), nla_len(start), maxtype, policy);
1077 }
1078
1079 /**
1080  * nla_for_each_attr - iterate over a stream of attributes
1081  * @pos: loop counter, set to current attribute
1082  * @head: head of attribute stream
1083  * @len: length of attribute stream
1084  * @rem: initialized to len, holds bytes currently remaining in stream
1085  */
1086 #define nla_for_each_attr(pos, head, len, rem) \
1087         for (pos = head, rem = len; \
1088              nla_ok(pos, rem); \
1089              pos = nla_next(pos, &(rem)))
1090
1091 /**
1092  * nla_for_each_nested - iterate over nested attributes
1093  * @pos: loop counter, set to current attribute
1094  * @nla: attribute containing the nested attributes
1095  * @rem: initialized to len, holds bytes currently remaining in stream
1096  */
1097 #define nla_for_each_nested(pos, nla, rem) \
1098         nla_for_each_attr(pos, nla_data(nla), nla_len(nla), rem)
1099
1100 #endif