lib/nlattr.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * NETLINK      Netlink attributes
   4  *
   5  *              Authors:        Thomas Graf <tgraf@suug.ch>
   6  *                              Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
   7  */
   8
   9 #include <linux/export.h>
  10 #include <linux/kernel.h>
  11 #include <linux/errno.h>
  12 #include <linux/jiffies.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/string.h>
  15 #include <linux/types.h>
  16 #include <net/netlink.h>
  17
  18 /* For these data types, attribute length should be exactly the given
  19  * size. However, to maintain compatibility with broken commands, if the
  20  * attribute length does not match the expected size a warning is emitted
  21  * to the user that the command is sending invalid data and needs to be fixed.
  22  */
  23 static const u8 nla_attr_len[NLA_TYPE_MAX+1] = {
  24         [NLA_U8]        = sizeof(u8),
  25         [NLA_U16]       = sizeof(u16),
  26         [NLA_U32]       = sizeof(u32),
  27         [NLA_U64]       = sizeof(u64),
  28         [NLA_S8]        = sizeof(s8),
  29         [NLA_S16]       = sizeof(s16),
  30         [NLA_S32]       = sizeof(s32),
  31         [NLA_S64]       = sizeof(s64),
  32 };
  33
  34 static const u8 nla_attr_minlen[NLA_TYPE_MAX+1] = {
  35         [NLA_U8]        = sizeof(u8),
  36         [NLA_U16]       = sizeof(u16),
  37         [NLA_U32]       = sizeof(u32),
  38         [NLA_U64]       = sizeof(u64),
  39         [NLA_MSECS]     = sizeof(u64),
  40         [NLA_NESTED]    = NLA_HDRLEN,
  41         [NLA_S8]        = sizeof(s8),
  42         [NLA_S16]       = sizeof(s16),
  43         [NLA_S32]       = sizeof(s32),
  44         [NLA_S64]       = sizeof(s64),
  45 };
  46
  47 static int validate_nla_bitfield32(const struct nlattr *nla,
  48                                    const u32 *valid_flags_mask)
  49 {
  50         const struct nla_bitfield32 *bf = nla_data(nla);
  51
  52         if (!valid_flags_mask)
  53                 return -EINVAL;
  54
  55         /*disallow invalid bit selector */
  56         if (bf->selector & ~*valid_flags_mask)
  57                 return -EINVAL;
  58
  59         /*disallow invalid bit values */
  60         if (bf->value & ~*valid_flags_mask)
  61                 return -EINVAL;
  62
  63         /*disallow valid bit values that are not selected*/
  64         if (bf->value & ~bf->selector)
  65                 return -EINVAL;
  66
  67         return 0;
  68 }
  69
  70 static int nla_validate_array(const struct nlattr *head, int len, int maxtype,
  71                               const struct nla_policy *policy,
  72                               struct netlink_ext_ack *extack,
  73                               unsigned int validate)
  74 {
  75         const struct nlattr *entry;
  76         int rem;
  77
  78         nla_for_each_attr(entry, head, len, rem) {
  79                 int ret;
  80
  81                 if (nla_len(entry) == 0)
  82                         continue;
  83
  84                 if (nla_len(entry) < NLA_HDRLEN) {
  85                         NL_SET_ERR_MSG_ATTR(extack, entry,
  86                                             "Array element too short");
  87                         return -ERANGE;
  88                 }
  89
  90                 ret = __nla_validate(nla_data(entry), nla_len(entry),
  91                                      maxtype, policy, validate, extack);
  92                 if (ret < 0)
  93                         return ret;
  94         }
  95
  96         return 0;
  97 }
  98
  99 static int nla_validate_int_range(const struct nla_policy *pt,
 100                                   const struct nlattr *nla,
 101                                   struct netlink_ext_ack *extack)
 102 {
 103         bool validate_min, validate_max;
 104         s64 value;
 105
 106         validate_min = pt->validation_type == NLA_VALIDATE_RANGE ||
 107                        pt->validation_type == NLA_VALIDATE_MIN;
 108         validate_max = pt->validation_type == NLA_VALIDATE_RANGE ||
 109                        pt->validation_type == NLA_VALIDATE_MAX;
 110
 111         switch (pt->type) {
 112         case NLA_U8:
 113                 value = nla_get_u8(nla);
 114                 break;
 115         case NLA_U16:
 116                 value = nla_get_u16(nla);
 117                 break;
 118         case NLA_U32:
 119                 value = nla_get_u32(nla);
 120                 break;
 121         case NLA_S8:
 122                 value = nla_get_s8(nla);
 123                 break;
 124         case NLA_S16:
 125                 value = nla_get_s16(nla);
 126                 break;
 127         case NLA_S32:
 128                 value = nla_get_s32(nla);
 129                 break;
 130         case NLA_S64:
 131                 value = nla_get_s64(nla);
 132                 break;
 133         case NLA_U64:
 134                 /* treat this one specially, since it may not fit into s64 */
 135                 if ((validate_min && nla_get_u64(nla) < pt->min) ||
 136                     (validate_max && nla_get_u64(nla) > pt->max)) {
 137                         NL_SET_ERR_MSG_ATTR(extack, nla,
 138                                             "integer out of range");
 139                         return -ERANGE;
 140                 }
 141                 return 0;
 142         default:
 143                 WARN_ON(1);
 144                 return -EINVAL;
 145         }
 146
 147         if ((validate_min && value < pt->min) ||
 148             (validate_max && value > pt->max)) {
 149                 NL_SET_ERR_MSG_ATTR(extack, nla,
 150                                     "integer out of range");
 151                 return -ERANGE;
 152         }
 153
 154         return 0;
 155 }
 156
 157 static int validate_nla(const struct nlattr *nla, int maxtype,
 158                         const struct nla_policy *policy, unsigned int validate,
 159                         struct netlink_ext_ack *extack)
 160 {
 161         u16 strict_start_type = policy[0].strict_start_type;
 162         const struct nla_policy *pt;
 163         int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
 164         int err = -ERANGE;
 165
 166         if (strict_start_type && type >= strict_start_type)
 167                 validate |= NL_VALIDATE_STRICT;
 168
 169         if (type <= 0 || type > maxtype)
 170                 return 0;
 171
 172         pt = &policy[type];
 173
 174         BUG_ON(pt->type > NLA_TYPE_MAX);
 175
 176         if ((nla_attr_len[pt->type] && attrlen != nla_attr_len[pt->type]) ||
 177             (pt->type == NLA_EXACT_LEN_WARN && attrlen != pt->len)) {
 178                 pr_warn_ratelimited("netlink: '%s': attribute type %d has an invalid length.\n",
 179                                     current->comm, type);
 180                 if (validate & NL_VALIDATE_STRICT_ATTRS) {
 181                         NL_SET_ERR_MSG_ATTR(extack, nla,
 182                                             "invalid attribute length");
 183                         return -EINVAL;
 184                 }
 185         }
 186
 187         switch (pt->type) {
 188         case NLA_EXACT_LEN:
 189                 if (attrlen != pt->len)
 190                         goto out_err;
 191                 break;
 192
 193         case NLA_REJECT:
 194                 if (extack && pt->validation_data) {
 195                         NL_SET_BAD_ATTR(extack, nla);
 196                         extack->_msg = pt->validation_data;
 197                         return -EINVAL;
 198                 }
 199                 err = -EINVAL;
 200                 goto out_err;
 201
 202         case NLA_FLAG:
 203                 if (attrlen > 0)
 204                         goto out_err;
 205                 break;
 206
 207         case NLA_BITFIELD32:
 208                 if (attrlen != sizeof(struct nla_bitfield32))
 209                         goto out_err;
 210
 211                 err = validate_nla_bitfield32(nla, pt->validation_data);
 212                 if (err)
 213                         goto out_err;
 214                 break;
 215
 216         case NLA_NUL_STRING:
 217                 if (pt->len)
 218                         minlen = min_t(int, attrlen, pt->len + 1);
 219                 else
 220                         minlen = attrlen;
 221
 222                 if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL) {
 223                         err = -EINVAL;
 224                         goto out_err;
 225                 }
 226                 /* fall through */
 227
 228         case NLA_STRING:
 229                 if (attrlen < 1)
 230                         goto out_err;
 231
 232                 if (pt->len) {
 233                         char *buf = nla_data(nla);
 234
 235                         if (buf[attrlen - 1] == '\0')
 236                                 attrlen--;
 237
 238                         if (attrlen > pt->len)
 239                                 goto out_err;
 240                 }
 241                 break;
 242
 243         case NLA_BINARY:
 244                 if (pt->len && attrlen > pt->len)
 245                         goto out_err;
 246                 break;
 247
 248         case NLA_NESTED:
 249                 /* a nested attributes is allowed to be empty; if its not,
 250                  * it must have a size of at least NLA_HDRLEN.
 251                  */
 252                 if (attrlen == 0)
 253                         break;
 254                 if (attrlen < NLA_HDRLEN)
 255                         goto out_err;
 256                 if (pt->validation_data) {
 257                         err = __nla_validate(nla_data(nla), nla_len(nla), pt->len,
 258                                              pt->validation_data, validate,
 259                                              extack);
 260                         if (err < 0) {
 261                                 /*
 262                                  * return directly to preserve the inner
 263                                  * error message/attribute pointer
 264                                  */
 265                                 return err;
 266                         }
 267                 }
 268                 break;
 269         case NLA_NESTED_ARRAY:
 270                 /* a nested array attribute is allowed to be empty; if its not,
 271                  * it must have a size of at least NLA_HDRLEN.
 272                  */
 273                 if (attrlen == 0)
 274                         break;
 275                 if (attrlen < NLA_HDRLEN)
 276                         goto out_err;
 277                 if (pt->validation_data) {
 278                         int err;
 279
 280                         err = nla_validate_array(nla_data(nla), nla_len(nla),
 281                                                  pt->len, pt->validation_data,
 282                                                  extack, validate);
 283                         if (err < 0) {
 284                                 /*
 285                                  * return directly to preserve the inner
 286                                  * error message/attribute pointer
 287                                  */
 288                                 return err;
 289                         }
 290                 }
 291                 break;
 292
 293         case NLA_UNSPEC:
 294                 if (validate & NL_VALIDATE_UNSPEC) {
 295                         NL_SET_ERR_MSG_ATTR(extack, nla,
 296                                             "Unsupported attribute");
 297                         return -EINVAL;
 298                 }
 299                 /* fall through */
 300         case NLA_MIN_LEN:
 301                 if (attrlen < pt->len)
 302                         goto out_err;
 303                 break;
 304
 305         default:
 306                 if (pt->len)
 307                         minlen = pt->len;
 308                 else
 309                         minlen = nla_attr_minlen[pt->type];
 310
 311                 if (attrlen < minlen)
 312                         goto out_err;
 313         }
 314
 315         /* further validation */
 316         switch (pt->validation_type) {
 317         case NLA_VALIDATE_NONE:
 318                 /* nothing to do */
 319                 break;
 320         case NLA_VALIDATE_RANGE:
 321         case NLA_VALIDATE_MIN:
 322         case NLA_VALIDATE_MAX:
 323                 err = nla_validate_int_range(pt, nla, extack);
 324                 if (err)
 325                         return err;
 326                 break;
 327         case NLA_VALIDATE_FUNCTION:
 328                 if (pt->validate) {
 329                         err = pt->validate(nla, extack);
 330                         if (err)
 331                                 return err;
 332                 }
 333                 break;
 334         }
 335
 336         return 0;
 337 out_err:
 338         NL_SET_ERR_MSG_ATTR(extack, nla, "Attribute failed policy validation");
 339         return err;
 340 }
 341
 342 static int __nla_validate_parse(const struct nlattr *head, int len, int maxtype,
 343                                 const struct nla_policy *policy,
 344                                 unsigned int validate,
 345                                 struct netlink_ext_ack *extack,
 346                                 struct nlattr **tb)
 347 {
 348         const struct nlattr *nla;
 349         int rem;
 350
 351         if (tb)
 352                 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
 353
 354         nla_for_each_attr(nla, head, len, rem) {
 355                 u16 type = nla_type(nla);
 356
 357                 if (type == 0 || type > maxtype) {
 358                         if (validate & NL_VALIDATE_MAXTYPE) {
 359                                 NL_SET_ERR_MSG(extack, "Unknown attribute type");
 360                                 return -EINVAL;
 361                         }
 362                         continue;
 363                 }
 364                 if (policy) {
 365                         int err = validate_nla(nla, maxtype, policy,
 366                                                validate, extack);
 367
 368                         if (err < 0)
 369                                 return err;
 370                 }
 371
 372                 if (tb)
 373                         tb[type] = (struct nlattr *)nla;
 374         }
 375
 376         if (unlikely(rem > 0)) {
 377                 pr_warn_ratelimited("netlink: %d bytes leftover after parsing attributes in process `%s'.\n",
 378                                     rem, current->comm);
 379                 NL_SET_ERR_MSG(extack, "bytes leftover after parsing attributes");
 380                 if (validate & NL_VALIDATE_TRAILING)
 381                         return -EINVAL;
 382         }
 383
 384         return 0;
 385 }
 386
 387 /**
 388  * __nla_validate - Validate a stream of attributes
 389  * @head: head of attribute stream
 390  * @len: length of attribute stream
 391  * @maxtype: maximum attribute type to be expected
 392  * @policy: validation policy
 393  * @validate: validation strictness
 394  * @extack: extended ACK report struct
 395  *
 396  * Validates all attributes in the specified attribute stream against the
 397  * specified policy. Validation depends on the validate flags passed, see
 398  * &enum netlink_validation for more details on that.
 399  * See documenation of struct nla_policy for more details.
 400  *
 401  * Returns 0 on success or a negative error code.
 402  */
 403 int __nla_validate(const struct nlattr *head, int len, int maxtype,
 404                    const struct nla_policy *policy, unsigned int validate,
 405                    struct netlink_ext_ack *extack)
 406 {
 407         return __nla_validate_parse(head, len, maxtype, policy, validate,
 408                                     extack, NULL);
 409 }
 410 EXPORT_SYMBOL(__nla_validate);
 411
 412 /**
 413  * nla_policy_len - Determin the max. length of a policy
 414  * @policy: policy to use
 415  * @n: number of policies
 416  *
 417  * Determines the max. length of the policy.  It is currently used
 418  * to allocated Netlink buffers roughly the size of the actual
 419  * message.
 420  *
 421  * Returns 0 on success or a negative error code.
 422  */
 423 int
 424 nla_policy_len(const struct nla_policy *p, int n)
 425 {
 426         int i, len = 0;
 427
 428         for (i = 0; i < n; i++, p++) {
 429                 if (p->len)
 430                         len += nla_total_size(p->len);
 431                 else if (nla_attr_len[p->type])
 432                         len += nla_total_size(nla_attr_len[p->type]);
 433                 else if (nla_attr_minlen[p->type])
 434                         len += nla_total_size(nla_attr_minlen[p->type]);
 435         }
 436
 437         return len;
 438 }
 439 EXPORT_SYMBOL(nla_policy_len);
 440
 441 /**
 442  * __nla_parse - Parse a stream of attributes into a tb buffer
 443  * @tb: destination array with maxtype+1 elements
 444  * @maxtype: maximum attribute type to be expected
 445  * @head: head of attribute stream
 446  * @len: length of attribute stream
 447  * @policy: validation policy
 448  * @validate: validation strictness
 449  * @extack: extended ACK pointer
 450  *
 451  * Parses a stream of attributes and stores a pointer to each attribute in
 452  * the tb array accessible via the attribute type.
 453  * Validation is controlled by the @validate parameter.
 454  *
 455  * Returns 0 on success or a negative error code.
 456  */
 457 int __nla_parse(struct nlattr **tb, int maxtype,
 458                 const struct nlattr *head, int len,
 459                 const struct nla_policy *policy, unsigned int validate,
 460                 struct netlink_ext_ack *extack)
 461 {
 462         return __nla_validate_parse(head, len, maxtype, policy, validate,
 463                                     extack, tb);
 464 }
 465 EXPORT_SYMBOL(__nla_parse);
 466
 467 /**
 468  * nla_find - Find a specific attribute in a stream of attributes
 469  * @head: head of attribute stream
 470  * @len: length of attribute stream
 471  * @attrtype: type of attribute to look for
 472  *
 473  * Returns the first attribute in the stream matching the specified type.
 474  */
 475 struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype)
 476 {
 477         const struct nlattr *nla;
 478         int rem;
 479
 480         nla_for_each_attr(nla, head, len, rem)
 481                 if (nla_type(nla) == attrtype)
 482                         return (struct nlattr *)nla;
 483
 484         return NULL;
 485 }
 486 EXPORT_SYMBOL(nla_find);
 487
 488 /**
 489  * nla_strlcpy - Copy string attribute payload into a sized buffer
 490  * @dst: where to copy the string to
 491  * @nla: attribute to copy the string from
 492  * @dstsize: size of destination buffer
 493  *
 494  * Copies at most dstsize - 1 bytes into the destination buffer.
 495  * The result is always a valid NUL-terminated string. Unlike
 496  * strlcpy the destination buffer is always padded out.
 497  *
 498  * Returns the length of the source buffer.
 499  */
 500 size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
 501 {
 502         size_t srclen = nla_len(nla);
 503         char *src = nla_data(nla);
 504
 505         if (srclen > 0 && src[srclen - 1] == '\0')
 506                 srclen--;
 507
 508         if (dstsize > 0) {
 509                 size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
 510
 511                 memset(dst, 0, dstsize);
 512                 memcpy(dst, src, len);
 513         }
 514
 515         return srclen;
 516 }
 517 EXPORT_SYMBOL(nla_strlcpy);
 518
 519 /**
 520  * nla_strdup - Copy string attribute payload into a newly allocated buffer
 521  * @nla: attribute to copy the string from
 522  * @flags: the type of memory to allocate (see kmalloc).
 523  *
 524  * Returns a pointer to the allocated buffer or NULL on error.
 525  */
 526 char *nla_strdup(const struct nlattr *nla, gfp_t flags)
 527 {
 528         size_t srclen = nla_len(nla);
 529         char *src = nla_data(nla), *dst;
 530
 531         if (srclen > 0 && src[srclen - 1] == '\0')
 532                 srclen--;
 533
 534         dst = kmalloc(srclen + 1, flags);
 535         if (dst != NULL) {
 536                 memcpy(dst, src, srclen);
 537                 dst[srclen] = '\0';
 538         }
 539         return dst;
 540 }
 541 EXPORT_SYMBOL(nla_strdup);
 542
 543 /**
 544  * nla_memcpy - Copy a netlink attribute into another memory area
 545  * @dest: where to copy to memcpy
 546  * @src: netlink attribute to copy from
 547  * @count: size of the destination area
 548  *
 549  * Note: The number of bytes copied is limited by the length of
 550  *       attribute's payload. memcpy
 551  *
 552  * Returns the number of bytes copied.
 553  */
 554 int nla_memcpy(void *dest, const struct nlattr *src, int count)
 555 {
 556         int minlen = min_t(int, count, nla_len(src));
 557
 558         memcpy(dest, nla_data(src), minlen);
 559         if (count > minlen)
 560                 memset(dest + minlen, 0, count - minlen);
 561
 562         return minlen;
 563 }
 564 EXPORT_SYMBOL(nla_memcpy);
 565
 566 /**
 567  * nla_memcmp - Compare an attribute with sized memory area
 568  * @nla: netlink attribute
 569  * @data: memory area
 570  * @size: size of memory area
 571  */
 572 int nla_memcmp(const struct nlattr *nla, const void *data,
 573                              size_t size)
 574 {
 575         int d = nla_len(nla) - size;
 576
 577         if (d == 0)
 578                 d = memcmp(nla_data(nla), data, size);
 579
 580         return d;
 581 }
 582 EXPORT_SYMBOL(nla_memcmp);
 583
 584 /**
 585  * nla_strcmp - Compare a string attribute against a string
 586  * @nla: netlink string attribute
 587  * @str: another string
 588  */
 589 int nla_strcmp(const struct nlattr *nla, const char *str)
 590 {
 591         int len = strlen(str);
 592         char *buf = nla_data(nla);
 593         int attrlen = nla_len(nla);
 594         int d;
 595
 596         if (attrlen > 0 && buf[attrlen - 1] == '\0')
 597                 attrlen--;
 598
 599         d = attrlen - len;
 600         if (d == 0)
 601                 d = memcmp(nla_data(nla), str, len);
 602
 603         return d;
 604 }
 605 EXPORT_SYMBOL(nla_strcmp);
 606
 607 #ifdef CONFIG_NET
 608 /**
 609  * __nla_reserve - reserve room for attribute on the skb
 610  * @skb: socket buffer to reserve room on
 611  * @attrtype: attribute type
 612  * @attrlen: length of attribute payload
 613  *
 614  * Adds a netlink attribute header to a socket buffer and reserves
 615  * room for the payload but does not copy it.
 616  *
 617  * The caller is responsible to ensure that the skb provides enough
 618  * tailroom for the attribute header and payload.
 619  */
 620 struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
 621 {
 622         struct nlattr *nla;
 623
 624         nla = skb_put(skb, nla_total_size(attrlen));
 625         nla->nla_type = attrtype;
 626         nla->nla_len = nla_attr_size(attrlen);
 627
 628         memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
 629
 630         return nla;
 631 }
 632 EXPORT_SYMBOL(__nla_reserve);
 633
 634 /**
 635  * __nla_reserve_64bit - reserve room for attribute on the skb and align it
 636  * @skb: socket buffer to reserve room on
 637  * @attrtype: attribute type
 638  * @attrlen: length of attribute payload
 639  * @padattr: attribute type for the padding
 640  *
 641  * Adds a netlink attribute header to a socket buffer and reserves
 642  * room for the payload but does not copy it. It also ensure that this
 643  * attribute will have a 64-bit aligned nla_data() area.
 644  *
 645  * The caller is responsible to ensure that the skb provides enough
 646  * tailroom for the attribute header and payload.
 647  */
 648 struct nlattr *__nla_reserve_64bit(struct sk_buff *skb, int attrtype,
 649                                    int attrlen, int padattr)
 650 {
 651         if (nla_need_padding_for_64bit(skb))
 652                 nla_align_64bit(skb, padattr);
 653
 654         return __nla_reserve(skb, attrtype, attrlen);
 655 }
 656 EXPORT_SYMBOL(__nla_reserve_64bit);
 657
 658 /**
 659  * __nla_reserve_nohdr - reserve room for attribute without header
 660  * @skb: socket buffer to reserve room on
 661  * @attrlen: length of attribute payload
 662  *
 663  * Reserves room for attribute payload without a header.
 664  *
 665  * The caller is responsible to ensure that the skb provides enough
 666  * tailroom for the payload.
 667  */
 668 void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
 669 {
 670         return skb_put_zero(skb, NLA_ALIGN(attrlen));
 671 }
 672 EXPORT_SYMBOL(__nla_reserve_nohdr);
 673
 674 /**
 675  * nla_reserve - reserve room for attribute on the skb
 676  * @skb: socket buffer to reserve room on
 677  * @attrtype: attribute type
 678  * @attrlen: length of attribute payload
 679  *
 680  * Adds a netlink attribute header to a socket buffer and reserves
 681  * room for the payload but does not copy it.
 682  *
 683  * Returns NULL if the tailroom of the skb is insufficient to store
 684  * the attribute header and payload.
 685  */
 686 struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
 687 {
 688         if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
 689                 return NULL;
 690
 691         return __nla_reserve(skb, attrtype, attrlen);
 692 }
 693 EXPORT_SYMBOL(nla_reserve);
 694
 695 /**
 696  * nla_reserve_64bit - reserve room for attribute on the skb and align it
 697  * @skb: socket buffer to reserve room on
 698  * @attrtype: attribute type
 699  * @attrlen: length of attribute payload
 700  * @padattr: attribute type for the padding
 701  *
 702  * Adds a netlink attribute header to a socket buffer and reserves
 703  * room for the payload but does not copy it. It also ensure that this
 704  * attribute will have a 64-bit aligned nla_data() area.
 705  *
 706  * Returns NULL if the tailroom of the skb is insufficient to store
 707  * the attribute header and payload.
 708  */
 709 struct nlattr *nla_reserve_64bit(struct sk_buff *skb, int attrtype, int attrlen,
 710                                  int padattr)
 711 {
 712         size_t len;
 713
 714         if (nla_need_padding_for_64bit(skb))
 715                 len = nla_total_size_64bit(attrlen);
 716         else
 717                 len = nla_total_size(attrlen);
 718         if (unlikely(skb_tailroom(skb) < len))
 719                 return NULL;
 720
 721         return __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
 722 }
 723 EXPORT_SYMBOL(nla_reserve_64bit);
 724
 725 /**
 726  * nla_reserve_nohdr - reserve room for attribute without header
 727  * @skb: socket buffer to reserve room on
 728  * @attrlen: length of attribute payload
 729  *
 730  * Reserves room for attribute payload without a header.
 731  *
 732  * Returns NULL if the tailroom of the skb is insufficient to store
 733  * the attribute payload.
 734  */
 735 void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
 736 {
 737         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
 738                 return NULL;
 739
 740         return __nla_reserve_nohdr(skb, attrlen);
 741 }
 742 EXPORT_SYMBOL(nla_reserve_nohdr);
 743
 744 /**
 745  * __nla_put - Add a netlink attribute to a socket buffer
 746  * @skb: socket buffer to add attribute to
 747  * @attrtype: attribute type
 748  * @attrlen: length of attribute payload
 749  * @data: head of attribute payload
 750  *
 751  * The caller is responsible to ensure that the skb provides enough
 752  * tailroom for the attribute header and payload.
 753  */
 754 void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
 755                              const void *data)
 756 {
 757         struct nlattr *nla;
 758
 759         nla = __nla_reserve(skb, attrtype, attrlen);
 760         memcpy(nla_data(nla), data, attrlen);
 761 }
 762 EXPORT_SYMBOL(__nla_put);
 763
 764 /**
 765  * __nla_put_64bit - Add a netlink attribute to a socket buffer and align it
 766  * @skb: socket buffer to add attribute to
 767  * @attrtype: attribute type
 768  * @attrlen: length of attribute payload
 769  * @data: head of attribute payload
 770  * @padattr: attribute type for the padding
 771  *
 772  * The caller is responsible to ensure that the skb provides enough
 773  * tailroom for the attribute header and payload.
 774  */
 775 void __nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
 776                      const void *data, int padattr)
 777 {
 778         struct nlattr *nla;
 779
 780         nla = __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
 781         memcpy(nla_data(nla), data, attrlen);
 782 }
 783 EXPORT_SYMBOL(__nla_put_64bit);
 784
 785 /**
 786  * __nla_put_nohdr - Add a netlink attribute without header
 787  * @skb: socket buffer to add attribute to
 788  * @attrlen: length of attribute payload
 789  * @data: head of attribute payload
 790  *
 791  * The caller is responsible to ensure that the skb provides enough
 792  * tailroom for the attribute payload.
 793  */
 794 void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
 795 {
 796         void *start;
 797
 798         start = __nla_reserve_nohdr(skb, attrlen);
 799         memcpy(start, data, attrlen);
 800 }
 801 EXPORT_SYMBOL(__nla_put_nohdr);
 802
 803 /**
 804  * nla_put - Add a netlink attribute to a socket buffer
 805  * @skb: socket buffer to add attribute to
 806  * @attrtype: attribute type
 807  * @attrlen: length of attribute payload
 808  * @data: head of attribute payload
 809  *
 810  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
 811  * the attribute header and payload.
 812  */
 813 int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
 814 {
 815         if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
 816                 return -EMSGSIZE;
 817
 818         __nla_put(skb, attrtype, attrlen, data);
 819         return 0;
 820 }
 821 EXPORT_SYMBOL(nla_put);
 822
 823 /**
 824  * nla_put_64bit - Add a netlink attribute to a socket buffer and align it
 825  * @skb: socket buffer to add attribute to
 826  * @attrtype: attribute type
 827  * @attrlen: length of attribute payload
 828  * @data: head of attribute payload
 829  * @padattr: attribute type for the padding
 830  *
 831  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
 832  * the attribute header and payload.
 833  */
 834 int nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
 835                   const void *data, int padattr)
 836 {
 837         size_t len;
 838
 839         if (nla_need_padding_for_64bit(skb))
 840                 len = nla_total_size_64bit(attrlen);
 841         else
 842                 len = nla_total_size(attrlen);
 843         if (unlikely(skb_tailroom(skb) < len))
 844                 return -EMSGSIZE;
 845
 846         __nla_put_64bit(skb, attrtype, attrlen, data, padattr);
 847         return 0;
 848 }
 849 EXPORT_SYMBOL(nla_put_64bit);
 850
 851 /**
 852  * nla_put_nohdr - Add a netlink attribute without header
 853  * @skb: socket buffer to add attribute to
 854  * @attrlen: length of attribute payload
 855  * @data: head of attribute payload
 856  *
 857  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
 858  * the attribute payload.
 859  */
 860 int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
 861 {
 862         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
 863                 return -EMSGSIZE;
 864
 865         __nla_put_nohdr(skb, attrlen, data);
 866         return 0;
 867 }
 868 EXPORT_SYMBOL(nla_put_nohdr);
 869
 870 /**
 871  * nla_append - Add a netlink attribute without header or padding
 872  * @skb: socket buffer to add attribute to
 873  * @attrlen: length of attribute payload
 874  * @data: head of attribute payload
 875  *
 876  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
 877  * the attribute payload.
 878  */
 879 int nla_append(struct sk_buff *skb, int attrlen, const void *data)
 880 {
 881         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
 882                 return -EMSGSIZE;
 883
 884         skb_put_data(skb, data, attrlen);
 885         return 0;
 886 }
 887 EXPORT_SYMBOL(nla_append);
 888 #endif