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           Don't use `len' field -- length verification is
 196  *                         done by checking len of nested header (or empty)
 197  *    NLA_NESTED_COMPAT    Minimum length of structure payload
 198  *    NLA_U8, NLA_U16,
 199  *    NLA_U32, NLA_U64,
 200  *    NLA_MSECS            Leaving the length field zero will verify the
 201  *                         given type fits, using it verifies minimum length
 202  *                         just like "All other"
 203  *    All other            Minimum length of attribute payload
 204  *
 205  * Example:
 206  * static const struct nla_policy my_policy[ATTR_MAX+1] = {
 207  *      [ATTR_FOO] = { .type = NLA_U16 },
 208  *      [ATTR_BAR] = { .type = NLA_STRING, .len = BARSIZ },
 209  *      [ATTR_BAZ] = { .len = sizeof(struct mystruct) },
 210  * };
 211  */
 212 struct nla_policy {
 213         u16             type;
 214         u16             len;
 215 };
 216
 217 /**
 218  * struct nl_info - netlink source information
 219  * @nlh: Netlink message header of original request
 220  * @pid: Netlink PID of requesting application
 221  */
 222 struct nl_info {
 223         struct nlmsghdr         *nlh;
 224         struct net              *nl_net;
 225         u32                     pid;
 226 };
 227
 228 extern int              netlink_rcv_skb(struct sk_buff *skb,
 229                                         int (*cb)(struct sk_buff *,
 230                                                   struct nlmsghdr *));
 231 extern int              nlmsg_notify(struct sock *sk, struct sk_buff *skb,
 232                                      u32 pid, unsigned int group, int report,
 233                                      gfp_t flags);
 234
 235 extern int              nla_validate(const struct nlattr *head,
 236                                      int len, int maxtype,
 237                                      const struct nla_policy *policy);
 238 extern int              nla_parse(struct nlattr **tb, int maxtype,
 239                                   const struct nlattr *head, int len,
 240                                   const struct nla_policy *policy);
 241 extern int              nla_policy_len(const struct nla_policy *, int);
 242 extern struct nlattr *  nla_find(const struct nlattr *head,
 243                                  int len, int attrtype);
 244 extern size_t           nla_strlcpy(char *dst, const struct nlattr *nla,
 245                                     size_t dstsize);
 246 extern int              nla_memcpy(void *dest, const struct nlattr *src, int count);
 247 extern int              nla_memcmp(const struct nlattr *nla, const void *data,
 248                                    size_t size);
 249 extern int              nla_strcmp(const struct nlattr *nla, const char *str);
 250 extern struct nlattr *  __nla_reserve(struct sk_buff *skb, int attrtype,
 251                                       int attrlen);
 252 extern void *           __nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
 253 extern struct nlattr *  nla_reserve(struct sk_buff *skb, int attrtype,
 254                                     int attrlen);
 255 extern void *           nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
 256 extern void             __nla_put(struct sk_buff *skb, int attrtype,
 257                                   int attrlen, const void *data);
 258 extern void             __nla_put_nohdr(struct sk_buff *skb, int attrlen,
 259                                         const void *data);
 260 extern int              nla_put(struct sk_buff *skb, int attrtype,
 261                                 int attrlen, const void *data);
 262 extern int              nla_put_nohdr(struct sk_buff *skb, int attrlen,
 263                                       const void *data);
 264 extern int              nla_append(struct sk_buff *skb, int attrlen,
 265                                    const void *data);
 266
 267 /**************************************************************************
 268  * Netlink Messages
 269  **************************************************************************/
 270
 271 /**
 272  * nlmsg_msg_size - length of netlink message not including padding
 273  * @payload: length of message payload
 274  */
 275 static inline int nlmsg_msg_size(int payload)
 276 {
 277         return NLMSG_HDRLEN + payload;
 278 }
 279
 280 /**
 281  * nlmsg_total_size - length of netlink message including padding
 282  * @payload: length of message payload
 283  */
 284 static inline int nlmsg_total_size(int payload)
 285 {
 286         return NLMSG_ALIGN(nlmsg_msg_size(payload));
 287 }
 288
 289 /**
 290  * nlmsg_padlen - length of padding at the message's tail
 291  * @payload: length of message payload
 292  */
 293 static inline int nlmsg_padlen(int payload)
 294 {
 295         return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
 296 }
 297
 298 /**
 299  * nlmsg_data - head of message payload
 300  * @nlh: netlink message header
 301  */
 302 static inline void *nlmsg_data(const struct nlmsghdr *nlh)
 303 {
 304         return (unsigned char *) nlh + NLMSG_HDRLEN;
 305 }
 306
 307 /**
 308  * nlmsg_len - length of message payload
 309  * @nlh: netlink message header
 310  */
 311 static inline int nlmsg_len(const struct nlmsghdr *nlh)
 312 {
 313         return nlh->nlmsg_len - NLMSG_HDRLEN;
 314 }
 315
 316 /**
 317  * nlmsg_attrdata - head of attributes data
 318  * @nlh: netlink message header
 319  * @hdrlen: length of family specific header
 320  */
 321 static inline struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh,
 322                                             int hdrlen)
 323 {
 324         unsigned char *data = nlmsg_data(nlh);
 325         return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
 326 }
 327
 328 /**
 329  * nlmsg_attrlen - length of attributes data
 330  * @nlh: netlink message header
 331  * @hdrlen: length of family specific header
 332  */
 333 static inline int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
 334 {
 335         return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);
 336 }
 337
 338 /**
 339  * nlmsg_ok - check if the netlink message fits into the remaining bytes
 340  * @nlh: netlink message header
 341  * @remaining: number of bytes remaining in message stream
 342  */
 343 static inline int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
 344 {
 345         return (remaining >= (int) sizeof(struct nlmsghdr) &&
 346                 nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
 347                 nlh->nlmsg_len <= remaining);
 348 }
 349
 350 /**
 351  * nlmsg_next - next netlink message in message stream
 352  * @nlh: netlink message header
 353  * @remaining: number of bytes remaining in message stream
 354  *
 355  * Returns the next netlink message in the message stream and
 356  * decrements remaining by the size of the current message.
 357  */
 358 static inline struct nlmsghdr *
 359 nlmsg_next(const struct nlmsghdr *nlh, int *remaining)
 360 {
 361         int totlen = NLMSG_ALIGN(nlh->nlmsg_len);
 362
 363         *remaining -= totlen;
 364
 365         return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
 366 }
 367
 368 /**
 369  * nlmsg_parse - parse attributes of a netlink message
 370  * @nlh: netlink message header
 371  * @hdrlen: length of family specific header
 372  * @tb: destination array with maxtype+1 elements
 373  * @maxtype: maximum attribute type to be expected
 374  * @policy: validation policy
 375  *
 376  * See nla_parse()
 377  */
 378 static inline int nlmsg_parse(const struct nlmsghdr *nlh, int hdrlen,
 379                               struct nlattr *tb[], int maxtype,
 380                               const struct nla_policy *policy)
 381 {
 382         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 383                 return -EINVAL;
 384
 385         return nla_parse(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
 386                          nlmsg_attrlen(nlh, hdrlen), policy);
 387 }
 388
 389 /**
 390  * nlmsg_find_attr - find a specific attribute in a netlink message
 391  * @nlh: netlink message header
 392  * @hdrlen: length of familiy specific header
 393  * @attrtype: type of attribute to look for
 394  *
 395  * Returns the first attribute which matches the specified type.
 396  */
 397 static inline struct nlattr *nlmsg_find_attr(const struct nlmsghdr *nlh,
 398                                              int hdrlen, int attrtype)
 399 {
 400         return nla_find(nlmsg_attrdata(nlh, hdrlen),
 401                         nlmsg_attrlen(nlh, hdrlen), attrtype);
 402 }
 403
 404 /**
 405  * nlmsg_validate - validate a netlink message including attributes
 406  * @nlh: netlinket message header
 407  * @hdrlen: length of familiy specific header
 408  * @maxtype: maximum attribute type to be expected
 409  * @policy: validation policy
 410  */
 411 static inline int nlmsg_validate(const struct nlmsghdr *nlh,
 412                                  int hdrlen, int maxtype,
 413                                  const struct nla_policy *policy)
 414 {
 415         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 416                 return -EINVAL;
 417
 418         return nla_validate(nlmsg_attrdata(nlh, hdrlen),
 419                             nlmsg_attrlen(nlh, hdrlen), maxtype, policy);
 420 }
 421
 422 /**
 423  * nlmsg_report - need to report back to application?
 424  * @nlh: netlink message header
 425  *
 426  * Returns 1 if a report back to the application is requested.
 427  */
 428 static inline int nlmsg_report(const struct nlmsghdr *nlh)
 429 {
 430         return !!(nlh->nlmsg_flags & NLM_F_ECHO);
 431 }
 432
 433 /**
 434  * nlmsg_for_each_attr - iterate over a stream of attributes
 435  * @pos: loop counter, set to current attribute
 436  * @nlh: netlink message header
 437  * @hdrlen: length of familiy specific header
 438  * @rem: initialized to len, holds bytes currently remaining in stream
 439  */
 440 #define nlmsg_for_each_attr(pos, nlh, hdrlen, rem) \
 441         nla_for_each_attr(pos, nlmsg_attrdata(nlh, hdrlen), \
 442                           nlmsg_attrlen(nlh, hdrlen), rem)
 443
 444 /**
 445  * nlmsg_put - Add a new netlink message to an skb
 446  * @skb: socket buffer to store message in
 447  * @pid: netlink process id
 448  * @seq: sequence number of message
 449  * @type: message type
 450  * @payload: length of message payload
 451  * @flags: message flags
 452  *
 453  * Returns NULL if the tailroom of the skb is insufficient to store
 454  * the message header and payload.
 455  */
 456 static inline struct nlmsghdr *nlmsg_put(struct sk_buff *skb, u32 pid, u32 seq,
 457                                          int type, int payload, int flags)
 458 {
 459         if (unlikely(skb_tailroom(skb) < nlmsg_total_size(payload)))
 460                 return NULL;
 461
 462         return __nlmsg_put(skb, pid, seq, type, payload, flags);
 463 }
 464
 465 /**
 466  * nlmsg_put_answer - Add a new callback based netlink message to an skb
 467  * @skb: socket buffer to store message in
 468  * @cb: netlink callback
 469  * @type: message type
 470  * @payload: length of message payload
 471  * @flags: message flags
 472  *
 473  * Returns NULL if the tailroom of the skb is insufficient to store
 474  * the message header and payload.
 475  */
 476 static inline struct nlmsghdr *nlmsg_put_answer(struct sk_buff *skb,
 477                                                 struct netlink_callback *cb,
 478                                                 int type, int payload,
 479                                                 int flags)
 480 {
 481         return nlmsg_put(skb, NETLINK_CB(cb->skb).pid, cb->nlh->nlmsg_seq,
 482                          type, payload, flags);
 483 }
 484
 485 /**
 486  * nlmsg_new - Allocate a new netlink message
 487  * @payload: size of the message payload
 488  * @flags: the type of memory to allocate.
 489  *
 490  * Use NLMSG_DEFAULT_SIZE if the size of the payload isn't known
 491  * and a good default is needed.
 492  */
 493 static inline struct sk_buff *nlmsg_new(size_t payload, gfp_t flags)
 494 {
 495         return alloc_skb(nlmsg_total_size(payload), flags);
 496 }
 497
 498 /**
 499  * nlmsg_end - Finalize a netlink message
 500  * @skb: socket buffer the message is stored in
 501  * @nlh: netlink message header
 502  *
 503  * Corrects the netlink message header to include the appeneded
 504  * attributes. Only necessary if attributes have been added to
 505  * the message.
 506  *
 507  * Returns the total data length of the skb.
 508  */
 509 static inline int nlmsg_end(struct sk_buff *skb, struct nlmsghdr *nlh)
 510 {
 511         nlh->nlmsg_len = skb_tail_pointer(skb) - (unsigned char *)nlh;
 512
 513         return skb->len;
 514 }
 515
 516 /**
 517  * nlmsg_get_pos - return current position in netlink message
 518  * @skb: socket buffer the message is stored in
 519  *
 520  * Returns a pointer to the current tail of the message.
 521  */
 522 static inline void *nlmsg_get_pos(struct sk_buff *skb)
 523 {
 524         return skb_tail_pointer(skb);
 525 }
 526
 527 /**
 528  * nlmsg_trim - Trim message to a mark
 529  * @skb: socket buffer the message is stored in
 530  * @mark: mark to trim to
 531  *
 532  * Trims the message to the provided mark.
 533  */
 534 static inline void nlmsg_trim(struct sk_buff *skb, const void *mark)
 535 {
 536         if (mark)
 537                 skb_trim(skb, (unsigned char *) mark - skb->data);
 538 }
 539
 540 /**
 541  * nlmsg_cancel - Cancel construction of a netlink message
 542  * @skb: socket buffer the message is stored in
 543  * @nlh: netlink message header
 544  *
 545  * Removes the complete netlink message including all
 546  * attributes from the socket buffer again.
 547  */
 548 static inline void nlmsg_cancel(struct sk_buff *skb, struct nlmsghdr *nlh)
 549 {
 550         nlmsg_trim(skb, nlh);
 551 }
 552
 553 /**
 554  * nlmsg_free - free a netlink message
 555  * @skb: socket buffer of netlink message
 556  */
 557 static inline void nlmsg_free(struct sk_buff *skb)
 558 {
 559         kfree_skb(skb);
 560 }
 561
 562 /**
 563  * nlmsg_multicast - multicast a netlink message
 564  * @sk: netlink socket to spread messages to
 565  * @skb: netlink message as socket buffer
 566  * @pid: own netlink pid to avoid sending to yourself
 567  * @group: multicast group id
 568  * @flags: allocation flags
 569  */
 570 static inline int nlmsg_multicast(struct sock *sk, struct sk_buff *skb,
 571                                   u32 pid, unsigned int group, gfp_t flags)
 572 {
 573         int err;
 574
 575         NETLINK_CB(skb).dst_group = group;
 576
 577         err = netlink_broadcast(sk, skb, pid, group, flags);
 578         if (err > 0)
 579                 err = 0;
 580
 581         return err;
 582 }
 583
 584 /**
 585  * nlmsg_unicast - unicast a netlink message
 586  * @sk: netlink socket to spread message to
 587  * @skb: netlink message as socket buffer
 588  * @pid: netlink pid of the destination socket
 589  */
 590 static inline int nlmsg_unicast(struct sock *sk, struct sk_buff *skb, u32 pid)
 591 {
 592         int err;
 593
 594         err = netlink_unicast(sk, skb, pid, MSG_DONTWAIT);
 595         if (err > 0)
 596                 err = 0;
 597
 598         return err;
 599 }
 600
 601 /**
 602  * nlmsg_for_each_msg - iterate over a stream of messages
 603  * @pos: loop counter, set to current message
 604  * @head: head of message stream
 605  * @len: length of message stream
 606  * @rem: initialized to len, holds bytes currently remaining in stream
 607  */
 608 #define nlmsg_for_each_msg(pos, head, len, rem) \
 609         for (pos = head, rem = len; \
 610              nlmsg_ok(pos, rem); \
 611              pos = nlmsg_next(pos, &(rem)))
 612
 613 /**
 614  * nl_dump_check_consistent - check if sequence is consistent and advertise if not
 615  * @cb: netlink callback structure that stores the sequence number
 616  * @nlh: netlink message header to write the flag to
 617  *
 618  * This function checks if the sequence (generation) number changed during dump
 619  * and if it did, advertises it in the netlink message header.
 620  *
 621  * The correct way to use it is to set cb->seq to the generation counter when
 622  * all locks for dumping have been acquired, and then call this function for
 623  * each message that is generated.
 624  *
 625  * Note that due to initialisation concerns, 0 is an invalid sequence number
 626  * and must not be used by code that uses this functionality.
 627  */
 628 static inline void
 629 nl_dump_check_consistent(struct netlink_callback *cb,
 630                          struct nlmsghdr *nlh)
 631 {
 632         if (cb->prev_seq && cb->seq != cb->prev_seq)
 633                 nlh->nlmsg_flags |= NLM_F_DUMP_INTR;
 634         cb->prev_seq = cb->seq;
 635 }
 636
 637 /**************************************************************************
 638  * Netlink Attributes
 639  **************************************************************************/
 640
 641 /**
 642  * nla_attr_size - length of attribute not including padding
 643  * @payload: length of payload
 644  */
 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 *
 731 nla_find_nested(const struct nlattr *nla, int attrtype)
 732 {
 733         return nla_find(nla_data(nla), nla_len(nla), attrtype);
 734 }
 735
 736 /**
 737  * nla_parse_nested - parse nested attributes
 738  * @tb: destination array with maxtype+1 elements
 739  * @maxtype: maximum attribute type to be expected
 740  * @nla: attribute containing the nested attributes
 741  * @policy: validation policy
 742  *
 743  * See nla_parse()
 744  */
 745 static inline int nla_parse_nested(struct nlattr *tb[], int maxtype,
 746                                    const struct nlattr *nla,
 747                                    const struct nla_policy *policy)
 748 {
 749         return nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy);
 750 }
 751
 752 /**
 753  * nla_put_u8 - Add a u8 netlink attribute to a socket buffer
 754  * @skb: socket buffer to add attribute to
 755  * @attrtype: attribute type
 756  * @value: numeric value
 757  */
 758 static inline int nla_put_u8(struct sk_buff *skb, int attrtype, u8 value)
 759 {
 760         return nla_put(skb, attrtype, sizeof(u8), &value);
 761 }
 762
 763 /**
 764  * nla_put_u16 - Add a u16 netlink attribute to a socket buffer
 765  * @skb: socket buffer to add attribute to
 766  * @attrtype: attribute type
 767  * @value: numeric value
 768  */
 769 static inline int nla_put_u16(struct sk_buff *skb, int attrtype, u16 value)
 770 {
 771         return nla_put(skb, attrtype, sizeof(u16), &value);
 772 }
 773
 774 /**
 775  * nla_put_u32 - Add a u32 netlink attribute to a socket buffer
 776  * @skb: socket buffer to add attribute to
 777  * @attrtype: attribute type
 778  * @value: numeric value
 779  */
 780 static inline int nla_put_u32(struct sk_buff *skb, int attrtype, u32 value)
 781 {
 782         return nla_put(skb, attrtype, sizeof(u32), &value);
 783 }
 784
 785 /**
 786  * nla_put_64 - Add a u64 netlink attribute to a socket buffer
 787  * @skb: socket buffer to add attribute to
 788  * @attrtype: attribute type
 789  * @value: numeric value
 790  */
 791 static inline int nla_put_u64(struct sk_buff *skb, int attrtype, u64 value)
 792 {
 793         return nla_put(skb, attrtype, sizeof(u64), &value);
 794 }
 795
 796 /**
 797  * nla_put_string - Add a string netlink attribute to a socket buffer
 798  * @skb: socket buffer to add attribute to
 799  * @attrtype: attribute type
 800  * @str: NUL terminated string
 801  */
 802 static inline int nla_put_string(struct sk_buff *skb, int attrtype,
 803                                  const char *str)
 804 {
 805         return nla_put(skb, attrtype, strlen(str) + 1, str);
 806 }
 807
 808 /**
 809  * nla_put_flag - Add a flag netlink attribute to a socket buffer
 810  * @skb: socket buffer to add attribute to
 811  * @attrtype: attribute type
 812  */
 813 static inline int nla_put_flag(struct sk_buff *skb, int attrtype)
 814 {
 815         return nla_put(skb, attrtype, 0, NULL);
 816 }
 817
 818 /**
 819  * nla_put_msecs - Add a msecs netlink attribute to a socket buffer
 820  * @skb: socket buffer to add attribute to
 821  * @attrtype: attribute type
 822  * @jiffies: number of msecs in jiffies
 823  */
 824 static inline int nla_put_msecs(struct sk_buff *skb, int attrtype,
 825                                 unsigned long jiffies)
 826 {
 827         u64 tmp = jiffies_to_msecs(jiffies);
 828         return nla_put(skb, attrtype, sizeof(u64), &tmp);
 829 }
 830
 831 #define NLA_PUT(skb, attrtype, attrlen, data) \
 832         do { \
 833                 if (unlikely(nla_put(skb, attrtype, attrlen, data) < 0)) \
 834                         goto nla_put_failure; \
 835         } while(0)
 836
 837 #define NLA_PUT_TYPE(skb, type, attrtype, value) \
 838         do { \
 839                 type __tmp = value; \
 840                 NLA_PUT(skb, attrtype, sizeof(type), &__tmp); \
 841         } while(0)
 842
 843 #define NLA_PUT_U8(skb, attrtype, value) \
 844         NLA_PUT_TYPE(skb, u8, attrtype, value)
 845
 846 #define NLA_PUT_U16(skb, attrtype, value) \
 847         NLA_PUT_TYPE(skb, u16, attrtype, value)
 848
 849 #define NLA_PUT_LE16(skb, attrtype, value) \
 850         NLA_PUT_TYPE(skb, __le16, attrtype, value)
 851
 852 #define NLA_PUT_BE16(skb, attrtype, value) \
 853         NLA_PUT_TYPE(skb, __be16, attrtype, value)
 854
 855 #define NLA_PUT_NET16(skb, attrtype, value) \
 856         NLA_PUT_BE16(skb, attrtype | NLA_F_NET_BYTEORDER, value)
 857
 858 #define NLA_PUT_U32(skb, attrtype, value) \
 859         NLA_PUT_TYPE(skb, u32, attrtype, value)
 860
 861 #define NLA_PUT_BE32(skb, attrtype, value) \
 862         NLA_PUT_TYPE(skb, __be32, attrtype, value)
 863
 864 #define NLA_PUT_NET32(skb, attrtype, value) \
 865         NLA_PUT_BE32(skb, attrtype | NLA_F_NET_BYTEORDER, value)
 866
 867 #define NLA_PUT_U64(skb, attrtype, value) \
 868         NLA_PUT_TYPE(skb, u64, attrtype, value)
 869
 870 #define NLA_PUT_BE64(skb, attrtype, value) \
 871         NLA_PUT_TYPE(skb, __be64, attrtype, value)
 872
 873 #define NLA_PUT_NET64(skb, attrtype, value) \
 874         NLA_PUT_BE64(skb, attrtype | NLA_F_NET_BYTEORDER, value)
 875
 876 #define NLA_PUT_STRING(skb, attrtype, value) \
 877         NLA_PUT(skb, attrtype, strlen(value) + 1, value)
 878
 879 #define NLA_PUT_FLAG(skb, attrtype) \
 880         NLA_PUT(skb, attrtype, 0, NULL)
 881
 882 #define NLA_PUT_MSECS(skb, attrtype, jiffies) \
 883         NLA_PUT_U64(skb, attrtype, jiffies_to_msecs(jiffies))
 884
 885 /**
 886  * nla_get_u32 - return payload of u32 attribute
 887  * @nla: u32 netlink attribute
 888  */
 889 static inline u32 nla_get_u32(const struct nlattr *nla)
 890 {
 891         return *(u32 *) nla_data(nla);
 892 }
 893
 894 /**
 895  * nla_get_be32 - return payload of __be32 attribute
 896  * @nla: __be32 netlink attribute
 897  */
 898 static inline __be32 nla_get_be32(const struct nlattr *nla)
 899 {
 900         return *(__be32 *) nla_data(nla);
 901 }
 902
 903 /**
 904  * nla_get_u16 - return payload of u16 attribute
 905  * @nla: u16 netlink attribute
 906  */
 907 static inline u16 nla_get_u16(const struct nlattr *nla)
 908 {
 909         return *(u16 *) nla_data(nla);
 910 }
 911
 912 /**
 913  * nla_get_be16 - return payload of __be16 attribute
 914  * @nla: __be16 netlink attribute
 915  */
 916 static inline __be16 nla_get_be16(const struct nlattr *nla)
 917 {
 918         return *(__be16 *) nla_data(nla);
 919 }
 920
 921 /**
 922  * nla_get_le16 - return payload of __le16 attribute
 923  * @nla: __le16 netlink attribute
 924  */
 925 static inline __le16 nla_get_le16(const struct nlattr *nla)
 926 {
 927         return *(__le16 *) nla_data(nla);
 928 }
 929
 930 /**
 931  * nla_get_u8 - return payload of u8 attribute
 932  * @nla: u8 netlink attribute
 933  */
 934 static inline u8 nla_get_u8(const struct nlattr *nla)
 935 {
 936         return *(u8 *) nla_data(nla);
 937 }
 938
 939 /**
 940  * nla_get_u64 - return payload of u64 attribute
 941  * @nla: u64 netlink attribute
 942  */
 943 static inline u64 nla_get_u64(const struct nlattr *nla)
 944 {
 945         u64 tmp;
 946
 947         nla_memcpy(&tmp, nla, sizeof(tmp));
 948
 949         return tmp;
 950 }
 951
 952 /**
 953  * nla_get_be64 - return payload of __be64 attribute
 954  * @nla: __be64 netlink attribute
 955  */
 956 static inline __be64 nla_get_be64(const struct nlattr *nla)
 957 {
 958         __be64 tmp;
 959
 960         nla_memcpy(&tmp, nla, sizeof(tmp));
 961
 962         return tmp;
 963 }
 964
 965 /**
 966  * nla_get_flag - return payload of flag attribute
 967  * @nla: flag netlink attribute
 968  */
 969 static inline int nla_get_flag(const struct nlattr *nla)
 970 {
 971         return !!nla;
 972 }
 973
 974 /**
 975  * nla_get_msecs - return payload of msecs attribute
 976  * @nla: msecs netlink attribute
 977  *
 978  * Returns the number of milliseconds in jiffies.
 979  */
 980 static inline unsigned long nla_get_msecs(const struct nlattr *nla)
 981 {
 982         u64 msecs = nla_get_u64(nla);
 983
 984         return msecs_to_jiffies((unsigned long) msecs);
 985 }
 986
 987 /**
 988  * nla_nest_start - Start a new level of nested attributes
 989  * @skb: socket buffer to add attributes to
 990  * @attrtype: attribute type of container
 991  *
 992  * Returns the container attribute
 993  */
 994 static inline struct nlattr *nla_nest_start(struct sk_buff *skb, int attrtype)
 995 {
 996         struct nlattr *start = (struct nlattr *)skb_tail_pointer(skb);
 997
 998         if (nla_put(skb, attrtype, 0, NULL) < 0)
 999                 return NULL;
1000
1001         return start;
1002 }
1003
1004 /**
1005  * nla_nest_end - Finalize nesting of attributes
1006  * @skb: socket buffer the attributes are stored in
1007  * @start: container attribute
1008  *
1009  * Corrects the container attribute header to include the all
1010  * appeneded attributes.
1011  *
1012  * Returns the total data length of the skb.
1013  */
1014 static inline int nla_nest_end(struct sk_buff *skb, struct nlattr *start)
1015 {
1016         start->nla_len = skb_tail_pointer(skb) - (unsigned char *)start;
1017         return skb->len;
1018 }
1019
1020 /**
1021  * nla_nest_cancel - Cancel nesting of attributes
1022  * @skb: socket buffer the message is stored in
1023  * @start: container attribute
1024  *
1025  * Removes the container attribute and including all nested
1026  * attributes. Returns -EMSGSIZE
1027  */
1028 static inline void nla_nest_cancel(struct sk_buff *skb, struct nlattr *start)
1029 {
1030         nlmsg_trim(skb, start);
1031 }
1032
1033 /**
1034  * nla_validate_nested - Validate a stream of nested attributes
1035  * @start: container attribute
1036  * @maxtype: maximum attribute type to be expected
1037  * @policy: validation policy
1038  *
1039  * Validates all attributes in the nested attribute stream against the
1040  * specified policy. Attributes with a type exceeding maxtype will be
1041  * ignored. See documenation of struct nla_policy for more details.
1042  *
1043  * Returns 0 on success or a negative error code.
1044  */
1045 static inline int nla_validate_nested(const struct nlattr *start, int maxtype,
1046                                       const struct nla_policy *policy)
1047 {
1048         return nla_validate(nla_data(start), nla_len(start), maxtype, policy);
1049 }
1050
1051 /**
1052  * nla_for_each_attr - iterate over a stream of attributes
1053  * @pos: loop counter, set to current attribute
1054  * @head: head of attribute stream
1055  * @len: length of attribute stream
1056  * @rem: initialized to len, holds bytes currently remaining in stream
1057  */
1058 #define nla_for_each_attr(pos, head, len, rem) \
1059         for (pos = head, rem = len; \
1060              nla_ok(pos, rem); \
1061              pos = nla_next(pos, &(rem)))
1062
1063 /**
1064  * nla_for_each_nested - iterate over nested attributes
1065  * @pos: loop counter, set to current attribute
1066  * @nla: attribute containing the nested attributes
1067  * @rem: initialized to len, holds bytes currently remaining in stream
1068  */
1069 #define nla_for_each_nested(pos, nla, rem) \
1070         nla_for_each_attr(pos, nla_data(nla), nla_len(nla), rem)
1071
1072 #endif