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 #include <linux/in6.h>
   8
   9 /* ========================================================================
  10  *         Netlink Messages and Attributes Interface (As Seen On TV)
  11  * ------------------------------------------------------------------------
  12  *                          Messages Interface
  13  * ------------------------------------------------------------------------
  14  *
  15  * Message Format:
  16  *    <--- nlmsg_total_size(payload)  --->
  17  *    <-- nlmsg_msg_size(payload) ->
  18  *   +----------+- - -+-------------+- - -+-------- - -
  19  *   | nlmsghdr | Pad |   Payload   | Pad | nlmsghdr
  20  *   +----------+- - -+-------------+- - -+-------- - -
  21  *   nlmsg_data(nlh)---^                   ^
  22  *   nlmsg_next(nlh)-----------------------+
  23  *
  24  * Payload Format:
  25  *    <---------------------- nlmsg_len(nlh) --------------------->
  26  *    <------ hdrlen ------>       <- nlmsg_attrlen(nlh, hdrlen) ->
  27  *   +----------------------+- - -+--------------------------------+
  28  *   |     Family Header    | Pad |           Attributes           |
  29  *   +----------------------+- - -+--------------------------------+
  30  *   nlmsg_attrdata(nlh, hdrlen)---^
  31  *
  32  * Data Structures:
  33  *   struct nlmsghdr                    netlink message header
  34  *
  35  * Message Construction:
  36  *   nlmsg_new()                        create a new netlink message
  37  *   nlmsg_put()                        add a netlink message to an skb
  38  *   nlmsg_put_answer()                 callback based nlmsg_put()
  39  *   nlmsg_end()                        finalize netlink message
  40  *   nlmsg_get_pos()                    return current position in message
  41  *   nlmsg_trim()                       trim part of message
  42  *   nlmsg_cancel()                     cancel message construction
  43  *   nlmsg_free()                       free a netlink message
  44  *
  45  * Message Sending:
  46  *   nlmsg_multicast()                  multicast message to several groups
  47  *   nlmsg_unicast()                    unicast a message to a single socket
  48  *   nlmsg_notify()                     send notification message
  49  *
  50  * Message Length Calculations:
  51  *   nlmsg_msg_size(payload)            length of message w/o padding
  52  *   nlmsg_total_size(payload)          length of message w/ padding
  53  *   nlmsg_padlen(payload)              length of padding at tail
  54  *
  55  * Message Payload Access:
  56  *   nlmsg_data(nlh)                    head of message payload
  57  *   nlmsg_len(nlh)                     length of message payload
  58  *   nlmsg_attrdata(nlh, hdrlen)        head of attributes data
  59  *   nlmsg_attrlen(nlh, hdrlen)         length of attributes data
  60  *
  61  * Message Parsing:
  62  *   nlmsg_ok(nlh, remaining)           does nlh fit into remaining bytes?
  63  *   nlmsg_next(nlh, remaining)         get next netlink message
  64  *   nlmsg_parse()                      parse attributes of a message
  65  *   nlmsg_find_attr()                  find an attribute in a message
  66  *   nlmsg_for_each_msg()               loop over all messages
  67  *   nlmsg_validate()                   validate netlink message incl. attrs
  68  *   nlmsg_for_each_attr()              loop over all attributes
  69  *
  70  * Misc:
  71  *   nlmsg_report()                     report back to application?
  72  *
  73  * ------------------------------------------------------------------------
  74  *                          Attributes Interface
  75  * ------------------------------------------------------------------------
  76  *
  77  * Attribute Format:
  78  *    <------- nla_total_size(payload) ------->
  79  *    <---- nla_attr_size(payload) ----->
  80  *   +----------+- - -+- - - - - - - - - +- - -+-------- - -
  81  *   |  Header  | Pad |     Payload      | Pad |  Header
  82  *   +----------+- - -+- - - - - - - - - +- - -+-------- - -
  83  *                     <- nla_len(nla) ->      ^
  84  *   nla_data(nla)----^                        |
  85  *   nla_next(nla)-----------------------------'
  86  *
  87  * Data Structures:
  88  *   struct nlattr                      netlink attribute header
  89  *
  90  * Attribute Construction:
  91  *   nla_reserve(skb, type, len)        reserve room for an attribute
  92  *   nla_reserve_nohdr(skb, len)        reserve room for an attribute w/o hdr
  93  *   nla_put(skb, type, len, data)      add attribute to skb
  94  *   nla_put_nohdr(skb, len, data)      add attribute w/o hdr
  95  *   nla_append(skb, len, data)         append data to skb
  96  *
  97  * Attribute Construction for Basic Types:
  98  *   nla_put_u8(skb, type, value)       add u8 attribute to skb
  99  *   nla_put_u16(skb, type, value)      add u16 attribute to skb
 100  *   nla_put_u32(skb, type, value)      add u32 attribute to skb
 101  *   nla_put_u64_64bit(skb, type,
 102  *                     value, padattr)  add u64 attribute to skb
 103  *   nla_put_s8(skb, type, value)       add s8 attribute to skb
 104  *   nla_put_s16(skb, type, value)      add s16 attribute to skb
 105  *   nla_put_s32(skb, type, value)      add s32 attribute to skb
 106  *   nla_put_s64(skb, type, value,
 107  *               padattr)               add s64 attribute to skb
 108  *   nla_put_string(skb, type, str)     add string attribute to skb
 109  *   nla_put_flag(skb, type)            add flag attribute to skb
 110  *   nla_put_msecs(skb, type, jiffies,
 111  *                 padattr)             add msecs attribute to skb
 112  *   nla_put_in_addr(skb, type, addr)   add IPv4 address attribute to skb
 113  *   nla_put_in6_addr(skb, type, addr)  add IPv6 address attribute to skb
 114  *
 115  * Nested Attributes Construction:
 116  *   nla_nest_start(skb, type)          start a nested attribute
 117  *   nla_nest_end(skb, nla)             finalize a nested attribute
 118  *   nla_nest_cancel(skb, nla)          cancel nested attribute construction
 119  *
 120  * Attribute Length Calculations:
 121  *   nla_attr_size(payload)             length of attribute w/o padding
 122  *   nla_total_size(payload)            length of attribute w/ padding
 123  *   nla_padlen(payload)                length of padding
 124  *
 125  * Attribute Payload Access:
 126  *   nla_data(nla)                      head of attribute payload
 127  *   nla_len(nla)                       length of attribute payload
 128  *
 129  * Attribute Payload Access for Basic Types:
 130  *   nla_get_u8(nla)                    get payload for a u8 attribute
 131  *   nla_get_u16(nla)                   get payload for a u16 attribute
 132  *   nla_get_u32(nla)                   get payload for a u32 attribute
 133  *   nla_get_u64(nla)                   get payload for a u64 attribute
 134  *   nla_get_s8(nla)                    get payload for a s8 attribute
 135  *   nla_get_s16(nla)                   get payload for a s16 attribute
 136  *   nla_get_s32(nla)                   get payload for a s32 attribute
 137  *   nla_get_s64(nla)                   get payload for a s64 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_S8,
 178         NLA_S16,
 179         NLA_S32,
 180         NLA_S64,
 181         NLA_BITFIELD32,
 182         __NLA_TYPE_MAX,
 183 };
 184
 185 #define NLA_TYPE_MAX (__NLA_TYPE_MAX - 1)
 186
 187 /**
 188  * struct nla_policy - attribute validation policy
 189  * @type: Type of attribute or NLA_UNSPEC
 190  * @len: Type specific length of payload
 191  *
 192  * Policies are defined as arrays of this struct, the array must be
 193  * accessible by attribute type up to the highest identifier to be expected.
 194  *
 195  * Meaning of `len' field:
 196  *    NLA_STRING           Maximum length of string
 197  *    NLA_NUL_STRING       Maximum length of string (excluding NUL)
 198  *    NLA_FLAG             Unused
 199  *    NLA_BINARY           Maximum length of attribute payload
 200  *    NLA_NESTED           Don't use `len' field -- length verification is
 201  *                         done by checking len of nested header (or empty)
 202  *    NLA_NESTED_COMPAT    Minimum length of structure payload
 203  *    NLA_U8, NLA_U16,
 204  *    NLA_U32, NLA_U64,
 205  *    NLA_S8, NLA_S16,
 206  *    NLA_S32, NLA_S64,
 207  *    NLA_MSECS            Leaving the length field zero will verify the
 208  *                         given type fits, using it verifies minimum length
 209  *                         just like "All other"
 210  *    NLA_BITFIELD32      A 32-bit bitmap/bitselector attribute
 211  *    All other            Minimum length of attribute payload
 212  *
 213  * Example:
 214  * static const struct nla_policy my_policy[ATTR_MAX+1] = {
 215  *      [ATTR_FOO] = { .type = NLA_U16 },
 216  *      [ATTR_BAR] = { .type = NLA_STRING, .len = BARSIZ },
 217  *      [ATTR_BAZ] = { .len = sizeof(struct mystruct) },
 218  *      [ATTR_GOO] = { .type = NLA_BITFIELD32, .validation_data = &myvalidflags },
 219  * };
 220  */
 221 struct nla_policy {
 222         u16             type;
 223         u16             len;
 224         void            *validation_data;
 225 };
 226
 227 /**
 228  * struct nl_info - netlink source information
 229  * @nlh: Netlink message header of original request
 230  * @portid: Netlink PORTID of requesting application
 231  */
 232 struct nl_info {
 233         struct nlmsghdr         *nlh;
 234         struct net              *nl_net;
 235         u32                     portid;
 236         bool                    skip_notify;
 237 };
 238
 239 int netlink_rcv_skb(struct sk_buff *skb,
 240                     int (*cb)(struct sk_buff *, struct nlmsghdr *,
 241                               struct netlink_ext_ack *));
 242 int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 portid,
 243                  unsigned int group, int report, gfp_t flags);
 244
 245 int nla_validate(const struct nlattr *head, int len, int maxtype,
 246                  const struct nla_policy *policy,
 247                  struct netlink_ext_ack *extack);
 248 int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head,
 249               int len, const struct nla_policy *policy,
 250               struct netlink_ext_ack *extack);
 251 int nla_policy_len(const struct nla_policy *, int);
 252 struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype);
 253 size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize);
 254 char *nla_strdup(const struct nlattr *nla, gfp_t flags);
 255 int nla_memcpy(void *dest, const struct nlattr *src, int count);
 256 int nla_memcmp(const struct nlattr *nla, const void *data, size_t size);
 257 int nla_strcmp(const struct nlattr *nla, const char *str);
 258 struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen);
 259 struct nlattr *__nla_reserve_64bit(struct sk_buff *skb, int attrtype,
 260                                    int attrlen, int padattr);
 261 void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
 262 struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen);
 263 struct nlattr *nla_reserve_64bit(struct sk_buff *skb, int attrtype,
 264                                  int attrlen, int padattr);
 265 void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
 266 void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
 267                const void *data);
 268 void __nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
 269                      const void *data, int padattr);
 270 void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data);
 271 int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data);
 272 int nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
 273                   const void *data, int padattr);
 274 int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data);
 275 int nla_append(struct sk_buff *skb, int attrlen, const void *data);
 276
 277 /**************************************************************************
 278  * Netlink Messages
 279  **************************************************************************/
 280
 281 /**
 282  * nlmsg_msg_size - length of netlink message not including padding
 283  * @payload: length of message payload
 284  */
 285 static inline int nlmsg_msg_size(int payload)
 286 {
 287         return NLMSG_HDRLEN + payload;
 288 }
 289
 290 /**
 291  * nlmsg_total_size - length of netlink message including padding
 292  * @payload: length of message payload
 293  */
 294 static inline int nlmsg_total_size(int payload)
 295 {
 296         return NLMSG_ALIGN(nlmsg_msg_size(payload));
 297 }
 298
 299 /**
 300  * nlmsg_padlen - length of padding at the message's tail
 301  * @payload: length of message payload
 302  */
 303 static inline int nlmsg_padlen(int payload)
 304 {
 305         return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
 306 }
 307
 308 /**
 309  * nlmsg_data - head of message payload
 310  * @nlh: netlink message header
 311  */
 312 static inline void *nlmsg_data(const struct nlmsghdr *nlh)
 313 {
 314         return (unsigned char *) nlh + NLMSG_HDRLEN;
 315 }
 316
 317 /**
 318  * nlmsg_len - length of message payload
 319  * @nlh: netlink message header
 320  */
 321 static inline int nlmsg_len(const struct nlmsghdr *nlh)
 322 {
 323         return nlh->nlmsg_len - NLMSG_HDRLEN;
 324 }
 325
 326 /**
 327  * nlmsg_attrdata - head of attributes data
 328  * @nlh: netlink message header
 329  * @hdrlen: length of family specific header
 330  */
 331 static inline struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh,
 332                                             int hdrlen)
 333 {
 334         unsigned char *data = nlmsg_data(nlh);
 335         return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
 336 }
 337
 338 /**
 339  * nlmsg_attrlen - length of attributes data
 340  * @nlh: netlink message header
 341  * @hdrlen: length of family specific header
 342  */
 343 static inline int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
 344 {
 345         return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);
 346 }
 347
 348 /**
 349  * nlmsg_ok - check if the netlink message fits into the remaining bytes
 350  * @nlh: netlink message header
 351  * @remaining: number of bytes remaining in message stream
 352  */
 353 static inline int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
 354 {
 355         return (remaining >= (int) sizeof(struct nlmsghdr) &&
 356                 nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
 357                 nlh->nlmsg_len <= remaining);
 358 }
 359
 360 /**
 361  * nlmsg_next - next netlink message in message stream
 362  * @nlh: netlink message header
 363  * @remaining: number of bytes remaining in message stream
 364  *
 365  * Returns the next netlink message in the message stream and
 366  * decrements remaining by the size of the current message.
 367  */
 368 static inline struct nlmsghdr *
 369 nlmsg_next(const struct nlmsghdr *nlh, int *remaining)
 370 {
 371         int totlen = NLMSG_ALIGN(nlh->nlmsg_len);
 372
 373         *remaining -= totlen;
 374
 375         return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
 376 }
 377
 378 /**
 379  * nlmsg_parse - parse attributes of a netlink message
 380  * @nlh: netlink message header
 381  * @hdrlen: length of family specific header
 382  * @tb: destination array with maxtype+1 elements
 383  * @maxtype: maximum attribute type to be expected
 384  * @policy: validation policy
 385  * @extack: extended ACK report struct
 386  *
 387  * See nla_parse()
 388  */
 389 static inline int nlmsg_parse(const struct nlmsghdr *nlh, int hdrlen,
 390                               struct nlattr *tb[], int maxtype,
 391                               const struct nla_policy *policy,
 392                               struct netlink_ext_ack *extack)
 393 {
 394         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 395                 return -EINVAL;
 396
 397         return nla_parse(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
 398                          nlmsg_attrlen(nlh, hdrlen), policy, extack);
 399 }
 400
 401 /**
 402  * nlmsg_find_attr - find a specific attribute in a netlink message
 403  * @nlh: netlink message header
 404  * @hdrlen: length of familiy specific header
 405  * @attrtype: type of attribute to look for
 406  *
 407  * Returns the first attribute which matches the specified type.
 408  */
 409 static inline struct nlattr *nlmsg_find_attr(const struct nlmsghdr *nlh,
 410                                              int hdrlen, int attrtype)
 411 {
 412         return nla_find(nlmsg_attrdata(nlh, hdrlen),
 413                         nlmsg_attrlen(nlh, hdrlen), attrtype);
 414 }
 415
 416 /**
 417  * nlmsg_validate - validate a netlink message including attributes
 418  * @nlh: netlinket message header
 419  * @hdrlen: length of familiy specific header
 420  * @maxtype: maximum attribute type to be expected
 421  * @policy: validation policy
 422  * @extack: extended ACK report struct
 423  */
 424 static inline int nlmsg_validate(const struct nlmsghdr *nlh,
 425                                  int hdrlen, int maxtype,
 426                                  const struct nla_policy *policy,
 427                                  struct netlink_ext_ack *extack)
 428 {
 429         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 430                 return -EINVAL;
 431
 432         return nla_validate(nlmsg_attrdata(nlh, hdrlen),
 433                             nlmsg_attrlen(nlh, hdrlen), maxtype, policy,
 434                             extack);
 435 }
 436
 437 /**
 438  * nlmsg_report - need to report back to application?
 439  * @nlh: netlink message header
 440  *
 441  * Returns 1 if a report back to the application is requested.
 442  */
 443 static inline int nlmsg_report(const struct nlmsghdr *nlh)
 444 {
 445         return !!(nlh->nlmsg_flags & NLM_F_ECHO);
 446 }
 447
 448 /**
 449  * nlmsg_for_each_attr - iterate over a stream of attributes
 450  * @pos: loop counter, set to current attribute
 451  * @nlh: netlink message header
 452  * @hdrlen: length of familiy specific header
 453  * @rem: initialized to len, holds bytes currently remaining in stream
 454  */
 455 #define nlmsg_for_each_attr(pos, nlh, hdrlen, rem) \
 456         nla_for_each_attr(pos, nlmsg_attrdata(nlh, hdrlen), \
 457                           nlmsg_attrlen(nlh, hdrlen), rem)
 458
 459 /**
 460  * nlmsg_put - Add a new netlink message to an skb
 461  * @skb: socket buffer to store message in
 462  * @portid: netlink PORTID of requesting application
 463  * @seq: sequence number of message
 464  * @type: message type
 465  * @payload: length of message payload
 466  * @flags: message flags
 467  *
 468  * Returns NULL if the tailroom of the skb is insufficient to store
 469  * the message header and payload.
 470  */
 471 static inline struct nlmsghdr *nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 472                                          int type, int payload, int flags)
 473 {
 474         if (unlikely(skb_tailroom(skb) < nlmsg_total_size(payload)))
 475                 return NULL;
 476
 477         return __nlmsg_put(skb, portid, seq, type, payload, flags);
 478 }
 479
 480 /**
 481  * nlmsg_put_answer - Add a new callback based netlink message to an skb
 482  * @skb: socket buffer to store message in
 483  * @cb: netlink callback
 484  * @type: message type
 485  * @payload: length of message payload
 486  * @flags: message flags
 487  *
 488  * Returns NULL if the tailroom of the skb is insufficient to store
 489  * the message header and payload.
 490  */
 491 static inline struct nlmsghdr *nlmsg_put_answer(struct sk_buff *skb,
 492                                                 struct netlink_callback *cb,
 493                                                 int type, int payload,
 494                                                 int flags)
 495 {
 496         return nlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
 497                          type, payload, flags);
 498 }
 499
 500 /**
 501  * nlmsg_new - Allocate a new netlink message
 502  * @payload: size of the message payload
 503  * @flags: the type of memory to allocate.
 504  *
 505  * Use NLMSG_DEFAULT_SIZE if the size of the payload isn't known
 506  * and a good default is needed.
 507  */
 508 static inline struct sk_buff *nlmsg_new(size_t payload, gfp_t flags)
 509 {
 510         return alloc_skb(nlmsg_total_size(payload), flags);
 511 }
 512
 513 /**
 514  * nlmsg_end - Finalize a netlink message
 515  * @skb: socket buffer the message is stored in
 516  * @nlh: netlink message header
 517  *
 518  * Corrects the netlink message header to include the appeneded
 519  * attributes. Only necessary if attributes have been added to
 520  * the message.
 521  */
 522 static inline void nlmsg_end(struct sk_buff *skb, struct nlmsghdr *nlh)
 523 {
 524         nlh->nlmsg_len = skb_tail_pointer(skb) - (unsigned char *)nlh;
 525 }
 526
 527 /**
 528  * nlmsg_get_pos - return current position in netlink message
 529  * @skb: socket buffer the message is stored in
 530  *
 531  * Returns a pointer to the current tail of the message.
 532  */
 533 static inline void *nlmsg_get_pos(struct sk_buff *skb)
 534 {
 535         return skb_tail_pointer(skb);
 536 }
 537
 538 /**
 539  * nlmsg_trim - Trim message to a mark
 540  * @skb: socket buffer the message is stored in
 541  * @mark: mark to trim to
 542  *
 543  * Trims the message to the provided mark.
 544  */
 545 static inline void nlmsg_trim(struct sk_buff *skb, const void *mark)
 546 {
 547         if (mark) {
 548                 WARN_ON((unsigned char *) mark < skb->data);
 549                 skb_trim(skb, (unsigned char *) mark - skb->data);
 550         }
 551 }
 552
 553 /**
 554  * nlmsg_cancel - Cancel construction of a netlink message
 555  * @skb: socket buffer the message is stored in
 556  * @nlh: netlink message header
 557  *
 558  * Removes the complete netlink message including all
 559  * attributes from the socket buffer again.
 560  */
 561 static inline void nlmsg_cancel(struct sk_buff *skb, struct nlmsghdr *nlh)
 562 {
 563         nlmsg_trim(skb, nlh);
 564 }
 565
 566 /**
 567  * nlmsg_free - free a netlink message
 568  * @skb: socket buffer of netlink message
 569  */
 570 static inline void nlmsg_free(struct sk_buff *skb)
 571 {
 572         kfree_skb(skb);
 573 }
 574
 575 /**
 576  * nlmsg_multicast - multicast a netlink message
 577  * @sk: netlink socket to spread messages to
 578  * @skb: netlink message as socket buffer
 579  * @portid: own netlink portid to avoid sending to yourself
 580  * @group: multicast group id
 581  * @flags: allocation flags
 582  */
 583 static inline int nlmsg_multicast(struct sock *sk, struct sk_buff *skb,
 584                                   u32 portid, unsigned int group, gfp_t flags)
 585 {
 586         int err;
 587
 588         NETLINK_CB(skb).dst_group = group;
 589
 590         err = netlink_broadcast(sk, skb, portid, group, flags);
 591         if (err > 0)
 592                 err = 0;
 593
 594         return err;
 595 }
 596
 597 /**
 598  * nlmsg_unicast - unicast a netlink message
 599  * @sk: netlink socket to spread message to
 600  * @skb: netlink message as socket buffer
 601  * @portid: netlink portid of the destination socket
 602  */
 603 static inline int nlmsg_unicast(struct sock *sk, struct sk_buff *skb, u32 portid)
 604 {
 605         int err;
 606
 607         err = netlink_unicast(sk, skb, portid, MSG_DONTWAIT);
 608         if (err > 0)
 609                 err = 0;
 610
 611         return err;
 612 }
 613
 614 /**
 615  * nlmsg_for_each_msg - iterate over a stream of messages
 616  * @pos: loop counter, set to current message
 617  * @head: head of message stream
 618  * @len: length of message stream
 619  * @rem: initialized to len, holds bytes currently remaining in stream
 620  */
 621 #define nlmsg_for_each_msg(pos, head, len, rem) \
 622         for (pos = head, rem = len; \
 623              nlmsg_ok(pos, rem); \
 624              pos = nlmsg_next(pos, &(rem)))
 625
 626 /**
 627  * nl_dump_check_consistent - check if sequence is consistent and advertise if not
 628  * @cb: netlink callback structure that stores the sequence number
 629  * @nlh: netlink message header to write the flag to
 630  *
 631  * This function checks if the sequence (generation) number changed during dump
 632  * and if it did, advertises it in the netlink message header.
 633  *
 634  * The correct way to use it is to set cb->seq to the generation counter when
 635  * all locks for dumping have been acquired, and then call this function for
 636  * each message that is generated.
 637  *
 638  * Note that due to initialisation concerns, 0 is an invalid sequence number
 639  * and must not be used by code that uses this functionality.
 640  */
 641 static inline void
 642 nl_dump_check_consistent(struct netlink_callback *cb,
 643                          struct nlmsghdr *nlh)
 644 {
 645         if (cb->prev_seq && cb->seq != cb->prev_seq)
 646                 nlh->nlmsg_flags |= NLM_F_DUMP_INTR;
 647         cb->prev_seq = cb->seq;
 648 }
 649
 650 /**************************************************************************
 651  * Netlink Attributes
 652  **************************************************************************/
 653
 654 /**
 655  * nla_attr_size - length of attribute not including padding
 656  * @payload: length of payload
 657  */
 658 static inline int nla_attr_size(int payload)
 659 {
 660         return NLA_HDRLEN + payload;
 661 }
 662
 663 /**
 664  * nla_total_size - total length of attribute including padding
 665  * @payload: length of payload
 666  */
 667 static inline int nla_total_size(int payload)
 668 {
 669         return NLA_ALIGN(nla_attr_size(payload));
 670 }
 671
 672 /**
 673  * nla_padlen - length of padding at the tail of attribute
 674  * @payload: length of payload
 675  */
 676 static inline int nla_padlen(int payload)
 677 {
 678         return nla_total_size(payload) - nla_attr_size(payload);
 679 }
 680
 681 /**
 682  * nla_type - attribute type
 683  * @nla: netlink attribute
 684  */
 685 static inline int nla_type(const struct nlattr *nla)
 686 {
 687         return nla->nla_type & NLA_TYPE_MASK;
 688 }
 689
 690 /**
 691  * nla_data - head of payload
 692  * @nla: netlink attribute
 693  */
 694 static inline void *nla_data(const struct nlattr *nla)
 695 {
 696         return (char *) nla + NLA_HDRLEN;
 697 }
 698
 699 /**
 700  * nla_len - length of payload
 701  * @nla: netlink attribute
 702  */
 703 static inline int nla_len(const struct nlattr *nla)
 704 {
 705         return nla->nla_len - NLA_HDRLEN;
 706 }
 707
 708 /**
 709  * nla_ok - check if the netlink attribute fits into the remaining bytes
 710  * @nla: netlink attribute
 711  * @remaining: number of bytes remaining in attribute stream
 712  */
 713 static inline int nla_ok(const struct nlattr *nla, int remaining)
 714 {
 715         return remaining >= (int) sizeof(*nla) &&
 716                nla->nla_len >= sizeof(*nla) &&
 717                nla->nla_len <= remaining;
 718 }
 719
 720 /**
 721  * nla_next - next netlink attribute in attribute stream
 722  * @nla: netlink attribute
 723  * @remaining: number of bytes remaining in attribute stream
 724  *
 725  * Returns the next netlink attribute in the attribute stream and
 726  * decrements remaining by the size of the current attribute.
 727  */
 728 static inline struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
 729 {
 730         unsigned int totlen = NLA_ALIGN(nla->nla_len);
 731
 732         *remaining -= totlen;
 733         return (struct nlattr *) ((char *) nla + totlen);
 734 }
 735
 736 /**
 737  * nla_find_nested - find attribute in a set of nested attributes
 738  * @nla: attribute containing the nested attributes
 739  * @attrtype: type of attribute to look for
 740  *
 741  * Returns the first attribute which matches the specified type.
 742  */
 743 static inline struct nlattr *
 744 nla_find_nested(const struct nlattr *nla, int attrtype)
 745 {
 746         return nla_find(nla_data(nla), nla_len(nla), attrtype);
 747 }
 748
 749 /**
 750  * nla_parse_nested - parse nested attributes
 751  * @tb: destination array with maxtype+1 elements
 752  * @maxtype: maximum attribute type to be expected
 753  * @nla: attribute containing the nested attributes
 754  * @policy: validation policy
 755  * @extack: extended ACK report struct
 756  *
 757  * See nla_parse()
 758  */
 759 static inline int nla_parse_nested(struct nlattr *tb[], int maxtype,
 760                                    const struct nlattr *nla,
 761                                    const struct nla_policy *policy,
 762                                    struct netlink_ext_ack *extack)
 763 {
 764         return nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy,
 765                          extack);
 766 }
 767
 768 /**
 769  * nla_put_u8 - Add a u8 netlink attribute to a socket buffer
 770  * @skb: socket buffer to add attribute to
 771  * @attrtype: attribute type
 772  * @value: numeric value
 773  */
 774 static inline int nla_put_u8(struct sk_buff *skb, int attrtype, u8 value)
 775 {
 776         /* temporary variables to work around GCC PR81715 with asan-stack=1 */
 777         u8 tmp = value;
 778
 779         return nla_put(skb, attrtype, sizeof(u8), &tmp);
 780 }
 781
 782 /**
 783  * nla_put_u16 - Add a u16 netlink attribute to a socket buffer
 784  * @skb: socket buffer to add attribute to
 785  * @attrtype: attribute type
 786  * @value: numeric value
 787  */
 788 static inline int nla_put_u16(struct sk_buff *skb, int attrtype, u16 value)
 789 {
 790         u16 tmp = value;
 791
 792         return nla_put(skb, attrtype, sizeof(u16), &tmp);
 793 }
 794
 795 /**
 796  * nla_put_be16 - Add a __be16 netlink attribute to a socket buffer
 797  * @skb: socket buffer to add attribute to
 798  * @attrtype: attribute type
 799  * @value: numeric value
 800  */
 801 static inline int nla_put_be16(struct sk_buff *skb, int attrtype, __be16 value)
 802 {
 803         __be16 tmp = value;
 804
 805         return nla_put(skb, attrtype, sizeof(__be16), &tmp);
 806 }
 807
 808 /**
 809  * nla_put_net16 - Add 16-bit network byte order netlink attribute to a socket buffer
 810  * @skb: socket buffer to add attribute to
 811  * @attrtype: attribute type
 812  * @value: numeric value
 813  */
 814 static inline int nla_put_net16(struct sk_buff *skb, int attrtype, __be16 value)
 815 {
 816         __be16 tmp = value;
 817
 818         return nla_put_be16(skb, attrtype | NLA_F_NET_BYTEORDER, tmp);
 819 }
 820
 821 /**
 822  * nla_put_le16 - Add a __le16 netlink attribute to a socket buffer
 823  * @skb: socket buffer to add attribute to
 824  * @attrtype: attribute type
 825  * @value: numeric value
 826  */
 827 static inline int nla_put_le16(struct sk_buff *skb, int attrtype, __le16 value)
 828 {
 829         __le16 tmp = value;
 830
 831         return nla_put(skb, attrtype, sizeof(__le16), &tmp);
 832 }
 833
 834 /**
 835  * nla_put_u32 - Add a u32 netlink attribute to a socket buffer
 836  * @skb: socket buffer to add attribute to
 837  * @attrtype: attribute type
 838  * @value: numeric value
 839  */
 840 static inline int nla_put_u32(struct sk_buff *skb, int attrtype, u32 value)
 841 {
 842         u32 tmp = value;
 843
 844         return nla_put(skb, attrtype, sizeof(u32), &tmp);
 845 }
 846
 847 /**
 848  * nla_put_be32 - Add a __be32 netlink attribute to a socket buffer
 849  * @skb: socket buffer to add attribute to
 850  * @attrtype: attribute type
 851  * @value: numeric value
 852  */
 853 static inline int nla_put_be32(struct sk_buff *skb, int attrtype, __be32 value)
 854 {
 855         __be32 tmp = value;
 856
 857         return nla_put(skb, attrtype, sizeof(__be32), &tmp);
 858 }
 859
 860 /**
 861  * nla_put_net32 - Add 32-bit network byte order netlink attribute to a socket buffer
 862  * @skb: socket buffer to add attribute to
 863  * @attrtype: attribute type
 864  * @value: numeric value
 865  */
 866 static inline int nla_put_net32(struct sk_buff *skb, int attrtype, __be32 value)
 867 {
 868         __be32 tmp = value;
 869
 870         return nla_put_be32(skb, attrtype | NLA_F_NET_BYTEORDER, tmp);
 871 }
 872
 873 /**
 874  * nla_put_le32 - Add a __le32 netlink attribute to a socket buffer
 875  * @skb: socket buffer to add attribute to
 876  * @attrtype: attribute type
 877  * @value: numeric value
 878  */
 879 static inline int nla_put_le32(struct sk_buff *skb, int attrtype, __le32 value)
 880 {
 881         __le32 tmp = value;
 882
 883         return nla_put(skb, attrtype, sizeof(__le32), &tmp);
 884 }
 885
 886 /**
 887  * nla_put_u64_64bit - Add a u64 netlink attribute to a skb and align it
 888  * @skb: socket buffer to add attribute to
 889  * @attrtype: attribute type
 890  * @value: numeric value
 891  * @padattr: attribute type for the padding
 892  */
 893 static inline int nla_put_u64_64bit(struct sk_buff *skb, int attrtype,
 894                                     u64 value, int padattr)
 895 {
 896         u64 tmp = value;
 897
 898         return nla_put_64bit(skb, attrtype, sizeof(u64), &tmp, padattr);
 899 }
 900
 901 /**
 902  * nla_put_be64 - Add a __be64 netlink attribute to a socket buffer and align it
 903  * @skb: socket buffer to add attribute to
 904  * @attrtype: attribute type
 905  * @value: numeric value
 906  * @padattr: attribute type for the padding
 907  */
 908 static inline int nla_put_be64(struct sk_buff *skb, int attrtype, __be64 value,
 909                                int padattr)
 910 {
 911         __be64 tmp = value;
 912
 913         return nla_put_64bit(skb, attrtype, sizeof(__be64), &tmp, padattr);
 914 }
 915
 916 /**
 917  * nla_put_net64 - Add 64-bit network byte order nlattr to a skb and align it
 918  * @skb: socket buffer to add attribute to
 919  * @attrtype: attribute type
 920  * @value: numeric value
 921  * @padattr: attribute type for the padding
 922  */
 923 static inline int nla_put_net64(struct sk_buff *skb, int attrtype, __be64 value,
 924                                 int padattr)
 925 {
 926         __be64 tmp = value;
 927
 928         return nla_put_be64(skb, attrtype | NLA_F_NET_BYTEORDER, tmp,
 929                             padattr);
 930 }
 931
 932 /**
 933  * nla_put_le64 - Add a __le64 netlink attribute to a socket buffer and align it
 934  * @skb: socket buffer to add attribute to
 935  * @attrtype: attribute type
 936  * @value: numeric value
 937  * @padattr: attribute type for the padding
 938  */
 939 static inline int nla_put_le64(struct sk_buff *skb, int attrtype, __le64 value,
 940                                int padattr)
 941 {
 942         __le64 tmp = value;
 943
 944         return nla_put_64bit(skb, attrtype, sizeof(__le64), &tmp, padattr);
 945 }
 946
 947 /**
 948  * nla_put_s8 - Add a s8 netlink attribute to a socket buffer
 949  * @skb: socket buffer to add attribute to
 950  * @attrtype: attribute type
 951  * @value: numeric value
 952  */
 953 static inline int nla_put_s8(struct sk_buff *skb, int attrtype, s8 value)
 954 {
 955         s8 tmp = value;
 956
 957         return nla_put(skb, attrtype, sizeof(s8), &tmp);
 958 }
 959
 960 /**
 961  * nla_put_s16 - Add a s16 netlink attribute to a socket buffer
 962  * @skb: socket buffer to add attribute to
 963  * @attrtype: attribute type
 964  * @value: numeric value
 965  */
 966 static inline int nla_put_s16(struct sk_buff *skb, int attrtype, s16 value)
 967 {
 968         s16 tmp = value;
 969
 970         return nla_put(skb, attrtype, sizeof(s16), &tmp);
 971 }
 972
 973 /**
 974  * nla_put_s32 - Add a s32 netlink attribute to a socket buffer
 975  * @skb: socket buffer to add attribute to
 976  * @attrtype: attribute type
 977  * @value: numeric value
 978  */
 979 static inline int nla_put_s32(struct sk_buff *skb, int attrtype, s32 value)
 980 {
 981         s32 tmp = value;
 982
 983         return nla_put(skb, attrtype, sizeof(s32), &tmp);
 984 }
 985
 986 /**
 987  * nla_put_s64 - Add a s64 netlink attribute to a socket buffer and align it
 988  * @skb: socket buffer to add attribute to
 989  * @attrtype: attribute type
 990  * @value: numeric value
 991  * @padattr: attribute type for the padding
 992  */
 993 static inline int nla_put_s64(struct sk_buff *skb, int attrtype, s64 value,
 994                               int padattr)
 995 {
 996         s64 tmp = value;
 997
 998         return nla_put_64bit(skb, attrtype, sizeof(s64), &tmp, padattr);
 999 }
1000
1001 /**
1002  * nla_put_string - Add a string netlink attribute to a socket buffer
1003  * @skb: socket buffer to add attribute to
1004  * @attrtype: attribute type
1005  * @str: NUL terminated string
1006  */
1007 static inline int nla_put_string(struct sk_buff *skb, int attrtype,
1008                                  const char *str)
1009 {
1010         return nla_put(skb, attrtype, strlen(str) + 1, str);
1011 }
1012
1013 /**
1014  * nla_put_flag - Add a flag netlink attribute to a socket buffer
1015  * @skb: socket buffer to add attribute to
1016  * @attrtype: attribute type
1017  */
1018 static inline int nla_put_flag(struct sk_buff *skb, int attrtype)
1019 {
1020         return nla_put(skb, attrtype, 0, NULL);
1021 }
1022
1023 /**
1024  * nla_put_msecs - Add a msecs netlink attribute to a skb and align it
1025  * @skb: socket buffer to add attribute to
1026  * @attrtype: attribute type
1027  * @njiffies: number of jiffies to convert to msecs
1028  * @padattr: attribute type for the padding
1029  */
1030 static inline int nla_put_msecs(struct sk_buff *skb, int attrtype,
1031                                 unsigned long njiffies, int padattr)
1032 {
1033         u64 tmp = jiffies_to_msecs(njiffies);
1034
1035         return nla_put_64bit(skb, attrtype, sizeof(u64), &tmp, padattr);
1036 }
1037
1038 /**
1039  * nla_put_in_addr - Add an IPv4 address netlink attribute to a socket
1040  * buffer
1041  * @skb: socket buffer to add attribute to
1042  * @attrtype: attribute type
1043  * @addr: IPv4 address
1044  */
1045 static inline int nla_put_in_addr(struct sk_buff *skb, int attrtype,
1046                                   __be32 addr)
1047 {
1048         __be32 tmp = addr;
1049
1050         return nla_put_be32(skb, attrtype, tmp);
1051 }
1052
1053 /**
1054  * nla_put_in6_addr - Add an IPv6 address netlink attribute to a socket
1055  * buffer
1056  * @skb: socket buffer to add attribute to
1057  * @attrtype: attribute type
1058  * @addr: IPv6 address
1059  */
1060 static inline int nla_put_in6_addr(struct sk_buff *skb, int attrtype,
1061                                    const struct in6_addr *addr)
1062 {
1063         return nla_put(skb, attrtype, sizeof(*addr), addr);
1064 }
1065
1066 /**
1067  * nla_get_u32 - return payload of u32 attribute
1068  * @nla: u32 netlink attribute
1069  */
1070 static inline u32 nla_get_u32(const struct nlattr *nla)
1071 {
1072         return *(u32 *) nla_data(nla);
1073 }
1074
1075 /**
1076  * nla_get_be32 - return payload of __be32 attribute
1077  * @nla: __be32 netlink attribute
1078  */
1079 static inline __be32 nla_get_be32(const struct nlattr *nla)
1080 {
1081         return *(__be32 *) nla_data(nla);
1082 }
1083
1084 /**
1085  * nla_get_le32 - return payload of __le32 attribute
1086  * @nla: __le32 netlink attribute
1087  */
1088 static inline __le32 nla_get_le32(const struct nlattr *nla)
1089 {
1090         return *(__le32 *) nla_data(nla);
1091 }
1092
1093 /**
1094  * nla_get_u16 - return payload of u16 attribute
1095  * @nla: u16 netlink attribute
1096  */
1097 static inline u16 nla_get_u16(const struct nlattr *nla)
1098 {
1099         return *(u16 *) nla_data(nla);
1100 }
1101
1102 /**
1103  * nla_get_be16 - return payload of __be16 attribute
1104  * @nla: __be16 netlink attribute
1105  */
1106 static inline __be16 nla_get_be16(const struct nlattr *nla)
1107 {
1108         return *(__be16 *) nla_data(nla);
1109 }
1110
1111 /**
1112  * nla_get_le16 - return payload of __le16 attribute
1113  * @nla: __le16 netlink attribute
1114  */
1115 static inline __le16 nla_get_le16(const struct nlattr *nla)
1116 {
1117         return *(__le16 *) nla_data(nla);
1118 }
1119
1120 /**
1121  * nla_get_u8 - return payload of u8 attribute
1122  * @nla: u8 netlink attribute
1123  */
1124 static inline u8 nla_get_u8(const struct nlattr *nla)
1125 {
1126         return *(u8 *) nla_data(nla);
1127 }
1128
1129 /**
1130  * nla_get_u64 - return payload of u64 attribute
1131  * @nla: u64 netlink attribute
1132  */
1133 static inline u64 nla_get_u64(const struct nlattr *nla)
1134 {
1135         u64 tmp;
1136
1137         nla_memcpy(&tmp, nla, sizeof(tmp));
1138
1139         return tmp;
1140 }
1141
1142 /**
1143  * nla_get_be64 - return payload of __be64 attribute
1144  * @nla: __be64 netlink attribute
1145  */
1146 static inline __be64 nla_get_be64(const struct nlattr *nla)
1147 {
1148         __be64 tmp;
1149
1150         nla_memcpy(&tmp, nla, sizeof(tmp));
1151
1152         return tmp;
1153 }
1154
1155 /**
1156  * nla_get_le64 - return payload of __le64 attribute
1157  * @nla: __le64 netlink attribute
1158  */
1159 static inline __le64 nla_get_le64(const struct nlattr *nla)
1160 {
1161         return *(__le64 *) nla_data(nla);
1162 }
1163
1164 /**
1165  * nla_get_s32 - return payload of s32 attribute
1166  * @nla: s32 netlink attribute
1167  */
1168 static inline s32 nla_get_s32(const struct nlattr *nla)
1169 {
1170         return *(s32 *) nla_data(nla);
1171 }
1172
1173 /**
1174  * nla_get_s16 - return payload of s16 attribute
1175  * @nla: s16 netlink attribute
1176  */
1177 static inline s16 nla_get_s16(const struct nlattr *nla)
1178 {
1179         return *(s16 *) nla_data(nla);
1180 }
1181
1182 /**
1183  * nla_get_s8 - return payload of s8 attribute
1184  * @nla: s8 netlink attribute
1185  */
1186 static inline s8 nla_get_s8(const struct nlattr *nla)
1187 {
1188         return *(s8 *) nla_data(nla);
1189 }
1190
1191 /**
1192  * nla_get_s64 - return payload of s64 attribute
1193  * @nla: s64 netlink attribute
1194  */
1195 static inline s64 nla_get_s64(const struct nlattr *nla)
1196 {
1197         s64 tmp;
1198
1199         nla_memcpy(&tmp, nla, sizeof(tmp));
1200
1201         return tmp;
1202 }
1203
1204 /**
1205  * nla_get_flag - return payload of flag attribute
1206  * @nla: flag netlink attribute
1207  */
1208 static inline int nla_get_flag(const struct nlattr *nla)
1209 {
1210         return !!nla;
1211 }
1212
1213 /**
1214  * nla_get_msecs - return payload of msecs attribute
1215  * @nla: msecs netlink attribute
1216  *
1217  * Returns the number of milliseconds in jiffies.
1218  */
1219 static inline unsigned long nla_get_msecs(const struct nlattr *nla)
1220 {
1221         u64 msecs = nla_get_u64(nla);
1222
1223         return msecs_to_jiffies((unsigned long) msecs);
1224 }
1225
1226 /**
1227  * nla_get_in_addr - return payload of IPv4 address attribute
1228  * @nla: IPv4 address netlink attribute
1229  */
1230 static inline __be32 nla_get_in_addr(const struct nlattr *nla)
1231 {
1232         return *(__be32 *) nla_data(nla);
1233 }
1234
1235 /**
1236  * nla_get_in6_addr - return payload of IPv6 address attribute
1237  * @nla: IPv6 address netlink attribute
1238  */
1239 static inline struct in6_addr nla_get_in6_addr(const struct nlattr *nla)
1240 {
1241         struct in6_addr tmp;
1242
1243         nla_memcpy(&tmp, nla, sizeof(tmp));
1244         return tmp;
1245 }
1246
1247 /**
1248  * nla_get_bitfield32 - return payload of 32 bitfield attribute
1249  * @nla: nla_bitfield32 attribute
1250  */
1251 static inline struct nla_bitfield32 nla_get_bitfield32(const struct nlattr *nla)
1252 {
1253         struct nla_bitfield32 tmp;
1254
1255         nla_memcpy(&tmp, nla, sizeof(tmp));
1256         return tmp;
1257 }
1258
1259 /**
1260  * nla_memdup - duplicate attribute memory (kmemdup)
1261  * @src: netlink attribute to duplicate from
1262  * @gfp: GFP mask
1263  */
1264 static inline void *nla_memdup(const struct nlattr *src, gfp_t gfp)
1265 {
1266         return kmemdup(nla_data(src), nla_len(src), gfp);
1267 }
1268
1269 /**
1270  * nla_nest_start - Start a new level of nested attributes
1271  * @skb: socket buffer to add attributes to
1272  * @attrtype: attribute type of container
1273  *
1274  * Returns the container attribute
1275  */
1276 static inline struct nlattr *nla_nest_start(struct sk_buff *skb, int attrtype)
1277 {
1278         struct nlattr *start = (struct nlattr *)skb_tail_pointer(skb);
1279
1280         if (nla_put(skb, attrtype, 0, NULL) < 0)
1281                 return NULL;
1282
1283         return start;
1284 }
1285
1286 /**
1287  * nla_nest_end - Finalize nesting of attributes
1288  * @skb: socket buffer the attributes are stored in
1289  * @start: container attribute
1290  *
1291  * Corrects the container attribute header to include the all
1292  * appeneded attributes.
1293  *
1294  * Returns the total data length of the skb.
1295  */
1296 static inline int nla_nest_end(struct sk_buff *skb, struct nlattr *start)
1297 {
1298         start->nla_len = skb_tail_pointer(skb) - (unsigned char *)start;
1299         return skb->len;
1300 }
1301
1302 /**
1303  * nla_nest_cancel - Cancel nesting of attributes
1304  * @skb: socket buffer the message is stored in
1305  * @start: container attribute
1306  *
1307  * Removes the container attribute and including all nested
1308  * attributes. Returns -EMSGSIZE
1309  */
1310 static inline void nla_nest_cancel(struct sk_buff *skb, struct nlattr *start)
1311 {
1312         nlmsg_trim(skb, start);
1313 }
1314
1315 /**
1316  * nla_validate_nested - Validate a stream of nested attributes
1317  * @start: container attribute
1318  * @maxtype: maximum attribute type to be expected
1319  * @policy: validation policy
1320  * @extack: extended ACK report struct
1321  *
1322  * Validates all attributes in the nested attribute stream against the
1323  * specified policy. Attributes with a type exceeding maxtype will be
1324  * ignored. See documenation of struct nla_policy for more details.
1325  *
1326  * Returns 0 on success or a negative error code.
1327  */
1328 static inline int nla_validate_nested(const struct nlattr *start, int maxtype,
1329                                       const struct nla_policy *policy,
1330                                       struct netlink_ext_ack *extack)
1331 {
1332         return nla_validate(nla_data(start), nla_len(start), maxtype, policy,
1333                             extack);
1334 }
1335
1336 /**
1337  * nla_need_padding_for_64bit - test 64-bit alignment of the next attribute
1338  * @skb: socket buffer the message is stored in
1339  *
1340  * Return true if padding is needed to align the next attribute (nla_data()) to
1341  * a 64-bit aligned area.
1342  */
1343 static inline bool nla_need_padding_for_64bit(struct sk_buff *skb)
1344 {
1345 #ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
1346         /* The nlattr header is 4 bytes in size, that's why we test
1347          * if the skb->data _is_ aligned.  A NOP attribute, plus
1348          * nlattr header for next attribute, will make nla_data()
1349          * 8-byte aligned.
1350          */
1351         if (IS_ALIGNED((unsigned long)skb_tail_pointer(skb), 8))
1352                 return true;
1353 #endif
1354         return false;
1355 }
1356
1357 /**
1358  * nla_align_64bit - 64-bit align the nla_data() of next attribute
1359  * @skb: socket buffer the message is stored in
1360  * @padattr: attribute type for the padding
1361  *
1362  * Conditionally emit a padding netlink attribute in order to make
1363  * the next attribute we emit have a 64-bit aligned nla_data() area.
1364  * This will only be done in architectures which do not have
1365  * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS defined.
1366  *
1367  * Returns zero on success or a negative error code.
1368  */
1369 static inline int nla_align_64bit(struct sk_buff *skb, int padattr)
1370 {
1371         if (nla_need_padding_for_64bit(skb) &&
1372             !nla_reserve(skb, padattr, 0))
1373                 return -EMSGSIZE;
1374
1375         return 0;
1376 }
1377
1378 /**
1379  * nla_total_size_64bit - total length of attribute including padding
1380  * @payload: length of payload
1381  */
1382 static inline int nla_total_size_64bit(int payload)
1383 {
1384         return NLA_ALIGN(nla_attr_size(payload))
1385 #ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
1386                 + NLA_ALIGN(nla_attr_size(0))
1387 #endif
1388                 ;
1389 }
1390
1391 /**
1392  * nla_for_each_attr - iterate over a stream of attributes
1393  * @pos: loop counter, set to current attribute
1394  * @head: head of attribute stream
1395  * @len: length of attribute stream
1396  * @rem: initialized to len, holds bytes currently remaining in stream
1397  */
1398 #define nla_for_each_attr(pos, head, len, rem) \
1399         for (pos = head, rem = len; \
1400              nla_ok(pos, rem); \
1401              pos = nla_next(pos, &(rem)))
1402
1403 /**
1404  * nla_for_each_nested - iterate over nested attributes
1405  * @pos: loop counter, set to current attribute
1406  * @nla: attribute containing the nested attributes
1407  * @rem: initialized to len, holds bytes currently remaining in stream
1408  */
1409 #define nla_for_each_nested(pos, nla, rem) \
1410         nla_for_each_attr(pos, nla_data(nla), nla_len(nla), rem)
1411
1412 /**
1413  * nla_is_last - Test if attribute is last in stream
1414  * @nla: attribute to test
1415  * @rem: bytes remaining in stream
1416  */
1417 static inline bool nla_is_last(const struct nlattr *nla, int rem)
1418 {
1419         return nla->nla_len == rem;
1420 }
1421
1422 #endif