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         if (validate & NL_VALIDATE_NESTED) {
 188                 if ((pt->type == NLA_NESTED || pt->type == NLA_NESTED_ARRAY) &&
 189                     !(nla->nla_type & NLA_F_NESTED)) {
 190                         NL_SET_ERR_MSG_ATTR(extack, nla,
 191                                             "NLA_F_NESTED is missing");
 192                         return -EINVAL;
 193                 }
 194                 if (pt->type != NLA_NESTED && pt->type != NLA_NESTED_ARRAY &&
 195                     pt->type != NLA_UNSPEC && (nla->nla_type & NLA_F_NESTED)) {
 196                         NL_SET_ERR_MSG_ATTR(extack, nla,
 197                                             "NLA_F_NESTED not expected");
 198                         return -EINVAL;
 199                 }
 200         }
 201
 202         switch (pt->type) {
 203         case NLA_EXACT_LEN:
 204                 if (attrlen != pt->len)
 205                         goto out_err;
 206                 break;
 207
 208         case NLA_REJECT:
 209                 if (extack && pt->validation_data) {
 210                         NL_SET_BAD_ATTR(extack, nla);
 211                         extack->_msg = pt->validation_data;
 212                         return -EINVAL;
 213                 }
 214                 err = -EINVAL;
 215                 goto out_err;
 216
 217         case NLA_FLAG:
 218                 if (attrlen > 0)
 219                         goto out_err;
 220                 break;
 221
 222         case NLA_BITFIELD32:
 223                 if (attrlen != sizeof(struct nla_bitfield32))
 224                         goto out_err;
 225
 226                 err = validate_nla_bitfield32(nla, pt->validation_data);
 227                 if (err)
 228                         goto out_err;
 229                 break;
 230
 231         case NLA_NUL_STRING:
 232                 if (pt->len)
 233                         minlen = min_t(int, attrlen, pt->len + 1);
 234                 else
 235                         minlen = attrlen;
 236
 237                 if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL) {
 238                         err = -EINVAL;
 239                         goto out_err;
 240                 }
 241                 /* fall through */
 242
 243         case NLA_STRING:
 244                 if (attrlen < 1)
 245                         goto out_err;
 246
 247                 if (pt->len) {
 248                         char *buf = nla_data(nla);
 249
 250                         if (buf[attrlen - 1] == '\0')
 251                                 attrlen--;
 252
 253                         if (attrlen > pt->len)
 254                                 goto out_err;
 255                 }
 256                 break;
 257
 258         case NLA_BINARY:
 259                 if (pt->len && attrlen > pt->len)
 260                         goto out_err;
 261                 break;
 262
 263         case NLA_NESTED:
 264                 /* a nested attributes is allowed to be empty; if its not,
 265                  * it must have a size of at least NLA_HDRLEN.
 266                  */
 267                 if (attrlen == 0)
 268                         break;
 269                 if (attrlen < NLA_HDRLEN)
 270                         goto out_err;
 271                 if (pt->validation_data) {
 272                         err = __nla_validate(nla_data(nla), nla_len(nla), pt->len,
 273                                              pt->validation_data, validate,
 274                                              extack);
 275                         if (err < 0) {
 276                                 /*
 277                                  * return directly to preserve the inner
 278                                  * error message/attribute pointer
 279                                  */
 280                                 return err;
 281                         }
 282                 }
 283                 break;
 284         case NLA_NESTED_ARRAY:
 285                 /* a nested array attribute is allowed to be empty; if its not,
 286                  * it must have a size of at least NLA_HDRLEN.
 287                  */
 288                 if (attrlen == 0)
 289                         break;
 290                 if (attrlen < NLA_HDRLEN)
 291                         goto out_err;
 292                 if (pt->validation_data) {
 293                         int err;
 294
 295                         err = nla_validate_array(nla_data(nla), nla_len(nla),
 296                                                  pt->len, pt->validation_data,
 297                                                  extack, validate);
 298                         if (err < 0) {
 299                                 /*
 300                                  * return directly to preserve the inner
 301                                  * error message/attribute pointer
 302                                  */
 303                                 return err;
 304                         }
 305                 }
 306                 break;
 307
 308         case NLA_UNSPEC:
 309                 if (validate & NL_VALIDATE_UNSPEC) {
 310                         NL_SET_ERR_MSG_ATTR(extack, nla,
 311                                             "Unsupported attribute");
 312                         return -EINVAL;
 313                 }
 314                 /* fall through */
 315         case NLA_MIN_LEN:
 316                 if (attrlen < pt->len)
 317                         goto out_err;
 318                 break;
 319
 320         default:
 321                 if (pt->len)
 322                         minlen = pt->len;
 323                 else
 324                         minlen = nla_attr_minlen[pt->type];
 325
 326                 if (attrlen < minlen)
 327                         goto out_err;
 328         }
 329
 330         /* further validation */
 331         switch (pt->validation_type) {
 332         case NLA_VALIDATE_NONE:
 333                 /* nothing to do */
 334                 break;
 335         case NLA_VALIDATE_RANGE:
 336         case NLA_VALIDATE_MIN:
 337         case NLA_VALIDATE_MAX:
 338                 err = nla_validate_int_range(pt, nla, extack);
 339                 if (err)
 340                         return err;
 341                 break;
 342         case NLA_VALIDATE_FUNCTION:
 343                 if (pt->validate) {
 344                         err = pt->validate(nla, extack);
 345                         if (err)
 346                                 return err;
 347                 }
 348                 break;
 349         }
 350
 351         return 0;
 352 out_err:
 353         NL_SET_ERR_MSG_ATTR(extack, nla, "Attribute failed policy validation");
 354         return err;
 355 }
 356
 357 static int __nla_validate_parse(const struct nlattr *head, int len, int maxtype,
 358                                 const struct nla_policy *policy,
 359                                 unsigned int validate,
 360                                 struct netlink_ext_ack *extack,
 361                                 struct nlattr **tb)
 362 {
 363         const struct nlattr *nla;
 364         int rem;
 365
 366         if (tb)
 367                 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
 368
 369         nla_for_each_attr(nla, head, len, rem) {
 370                 u16 type = nla_type(nla);
 371
 372                 if (type == 0 || type > maxtype) {
 373                         if (validate & NL_VALIDATE_MAXTYPE) {
 374                                 NL_SET_ERR_MSG_ATTR(extack, nla,
 375                                                     "Unknown attribute type");
 376                                 return -EINVAL;
 377                         }
 378                         continue;
 379                 }
 380                 if (policy) {
 381                         int err = validate_nla(nla, maxtype, policy,
 382                                                validate, extack);
 383
 384                         if (err < 0)
 385                                 return err;
 386                 }
 387
 388                 if (tb)
 389                         tb[type] = (struct nlattr *)nla;
 390         }
 391
 392         if (unlikely(rem > 0)) {
 393                 pr_warn_ratelimited("netlink: %d bytes leftover after parsing attributes in process `%s'.\n",
 394                                     rem, current->comm);
 395                 NL_SET_ERR_MSG(extack, "bytes leftover after parsing attributes");
 396                 if (validate & NL_VALIDATE_TRAILING)
 397                         return -EINVAL;
 398         }
 399
 400         return 0;
 401 }
 402
 403 /**
 404  * __nla_validate - Validate a stream of attributes
 405  * @head: head of attribute stream
 406  * @len: length of attribute stream
 407  * @maxtype: maximum attribute type to be expected
 408  * @policy: validation policy
 409  * @validate: validation strictness
 410  * @extack: extended ACK report struct
 411  *
 412  * Validates all attributes in the specified attribute stream against the
 413  * specified policy. Validation depends on the validate flags passed, see
 414  * &enum netlink_validation for more details on that.
 415  * See documenation of struct nla_policy for more details.
 416  *
 417  * Returns 0 on success or a negative error code.
 418  */
 419 int __nla_validate(const struct nlattr *head, int len, int maxtype,
 420                    const struct nla_policy *policy, unsigned int validate,
 421                    struct netlink_ext_ack *extack)
 422 {
 423         return __nla_validate_parse(head, len, maxtype, policy, validate,
 424                                     extack, NULL);
 425 }
 426 EXPORT_SYMBOL(__nla_validate);
 427
 428 /**
 429  * nla_policy_len - Determin the max. length of a policy
 430  * @policy: policy to use
 431  * @n: number of policies
 432  *
 433  * Determines the max. length of the policy.  It is currently used
 434  * to allocated Netlink buffers roughly the size of the actual
 435  * message.
 436  *
 437  * Returns 0 on success or a negative error code.
 438  */
 439 int
 440 nla_policy_len(const struct nla_policy *p, int n)
 441 {
 442         int i, len = 0;
 443
 444         for (i = 0; i < n; i++, p++) {
 445                 if (p->len)
 446                         len += nla_total_size(p->len);
 447                 else if (nla_attr_len[p->type])
 448                         len += nla_total_size(nla_attr_len[p->type]);
 449                 else if (nla_attr_minlen[p->type])
 450                         len += nla_total_size(nla_attr_minlen[p->type]);
 451         }
 452
 453         return len;
 454 }
 455 EXPORT_SYMBOL(nla_policy_len);
 456
 457 /**
 458  * __nla_parse - Parse a stream of attributes into a tb buffer
 459  * @tb: destination array with maxtype+1 elements
 460  * @maxtype: maximum attribute type to be expected
 461  * @head: head of attribute stream
 462  * @len: length of attribute stream
 463  * @policy: validation policy
 464  * @validate: validation strictness
 465  * @extack: extended ACK pointer
 466  *
 467  * Parses a stream of attributes and stores a pointer to each attribute in
 468  * the tb array accessible via the attribute type.
 469  * Validation is controlled by the @validate parameter.
 470  *
 471  * Returns 0 on success or a negative error code.
 472  */
 473 int __nla_parse(struct nlattr **tb, int maxtype,
 474                 const struct nlattr *head, int len,
 475                 const struct nla_policy *policy, unsigned int validate,
 476                 struct netlink_ext_ack *extack)
 477 {
 478         return __nla_validate_parse(head, len, maxtype, policy, validate,
 479                                     extack, tb);
 480 }
 481 EXPORT_SYMBOL(__nla_parse);
 482
 483 /**
 484  * nla_find - Find a specific attribute in a stream of attributes
 485  * @head: head of attribute stream
 486  * @len: length of attribute stream
 487  * @attrtype: type of attribute to look for
 488  *
 489  * Returns the first attribute in the stream matching the specified type.
 490  */
 491 struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype)
 492 {
 493         const struct nlattr *nla;
 494         int rem;
 495
 496         nla_for_each_attr(nla, head, len, rem)
 497                 if (nla_type(nla) == attrtype)
 498                         return (struct nlattr *)nla;
 499
 500         return NULL;
 501 }
 502 EXPORT_SYMBOL(nla_find);
 503
 504 /**
 505  * nla_strlcpy - Copy string attribute payload into a sized buffer
 506  * @dst: where to copy the string to
 507  * @nla: attribute to copy the string from
 508  * @dstsize: size of destination buffer
 509  *
 510  * Copies at most dstsize - 1 bytes into the destination buffer.
 511  * The result is always a valid NUL-terminated string. Unlike
 512  * strlcpy the destination buffer is always padded out.
 513  *
 514  * Returns the length of the source buffer.
 515  */
 516 size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
 517 {
 518         size_t srclen = nla_len(nla);
 519         char *src = nla_data(nla);
 520
 521         if (srclen > 0 && src[srclen - 1] == '\0')
 522                 srclen--;
 523
 524         if (dstsize > 0) {
 525                 size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
 526
 527                 memset(dst, 0, dstsize);
 528                 memcpy(dst, src, len);
 529         }
 530
 531         return srclen;
 532 }
 533 EXPORT_SYMBOL(nla_strlcpy);
 534
 535 /**
 536  * nla_strdup - Copy string attribute payload into a newly allocated buffer
 537  * @nla: attribute to copy the string from
 538  * @flags: the type of memory to allocate (see kmalloc).
 539  *
 540  * Returns a pointer to the allocated buffer or NULL on error.
 541  */
 542 char *nla_strdup(const struct nlattr *nla, gfp_t flags)
 543 {
 544         size_t srclen = nla_len(nla);
 545         char *src = nla_data(nla), *dst;
 546
 547         if (srclen > 0 && src[srclen - 1] == '\0')
 548                 srclen--;
 549
 550         dst = kmalloc(srclen + 1, flags);
 551         if (dst != NULL) {
 552                 memcpy(dst, src, srclen);
 553                 dst[srclen] = '\0';
 554         }
 555         return dst;
 556 }
 557 EXPORT_SYMBOL(nla_strdup);
 558
 559 /**
 560  * nla_memcpy - Copy a netlink attribute into another memory area
 561  * @dest: where to copy to memcpy
 562  * @src: netlink attribute to copy from
 563  * @count: size of the destination area
 564  *
 565  * Note: The number of bytes copied is limited by the length of
 566  *       attribute's payload. memcpy
 567  *
 568  * Returns the number of bytes copied.
 569  */
 570 int nla_memcpy(void *dest, const struct nlattr *src, int count)
 571 {
 572         int minlen = min_t(int, count, nla_len(src));
 573
 574         memcpy(dest, nla_data(src), minlen);
 575         if (count > minlen)
 576                 memset(dest + minlen, 0, count - minlen);
 577
 578         return minlen;
 579 }
 580 EXPORT_SYMBOL(nla_memcpy);
 581
 582 /**
 583  * nla_memcmp - Compare an attribute with sized memory area
 584  * @nla: netlink attribute
 585  * @data: memory area
 586  * @size: size of memory area
 587  */
 588 int nla_memcmp(const struct nlattr *nla, const void *data,
 589                              size_t size)
 590 {
 591         int d = nla_len(nla) - size;
 592
 593         if (d == 0)
 594                 d = memcmp(nla_data(nla), data, size);
 595
 596         return d;
 597 }
 598 EXPORT_SYMBOL(nla_memcmp);
 599
 600 /**
 601  * nla_strcmp - Compare a string attribute against a string
 602  * @nla: netlink string attribute
 603  * @str: another string
 604  */
 605 int nla_strcmp(const struct nlattr *nla, const char *str)
 606 {
 607         int len = strlen(str);
 608         char *buf = nla_data(nla);
 609         int attrlen = nla_len(nla);
 610         int d;
 611
 612         if (attrlen > 0 && buf[attrlen - 1] == '\0')
 613                 attrlen--;
 614
 615         d = attrlen - len;
 616         if (d == 0)
 617                 d = memcmp(nla_data(nla), str, len);
 618
 619         return d;
 620 }
 621 EXPORT_SYMBOL(nla_strcmp);
 622
 623 #ifdef CONFIG_NET
 624 /**
 625  * __nla_reserve - reserve room for attribute on the skb
 626  * @skb: socket buffer to reserve room on
 627  * @attrtype: attribute type
 628  * @attrlen: length of attribute payload
 629  *
 630  * Adds a netlink attribute header to a socket buffer and reserves
 631  * room for the payload but does not copy it.
 632  *
 633  * The caller is responsible to ensure that the skb provides enough
 634  * tailroom for the attribute header and payload.
 635  */
 636 struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
 637 {
 638         struct nlattr *nla;
 639
 640         nla = skb_put(skb, nla_total_size(attrlen));
 641         nla->nla_type = attrtype;
 642         nla->nla_len = nla_attr_size(attrlen);
 643
 644         memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
 645
 646         return nla;
 647 }
 648 EXPORT_SYMBOL(__nla_reserve);
 649
 650 /**
 651  * __nla_reserve_64bit - reserve room for attribute on the skb and align it
 652  * @skb: socket buffer to reserve room on
 653  * @attrtype: attribute type
 654  * @attrlen: length of attribute payload
 655  * @padattr: attribute type for the padding
 656  *
 657  * Adds a netlink attribute header to a socket buffer and reserves
 658  * room for the payload but does not copy it. It also ensure that this
 659  * attribute will have a 64-bit aligned nla_data() area.
 660  *
 661  * The caller is responsible to ensure that the skb provides enough
 662  * tailroom for the attribute header and payload.
 663  */
 664 struct nlattr *__nla_reserve_64bit(struct sk_buff *skb, int attrtype,
 665                                    int attrlen, int padattr)
 666 {
 667         if (nla_need_padding_for_64bit(skb))
 668                 nla_align_64bit(skb, padattr);
 669
 670         return __nla_reserve(skb, attrtype, attrlen);
 671 }
 672 EXPORT_SYMBOL(__nla_reserve_64bit);
 673
 674 /**
 675  * __nla_reserve_nohdr - reserve room for attribute without header
 676  * @skb: socket buffer to reserve room on
 677  * @attrlen: length of attribute payload
 678  *
 679  * Reserves room for attribute payload without a header.
 680  *
 681  * The caller is responsible to ensure that the skb provides enough
 682  * tailroom for the payload.
 683  */
 684 void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
 685 {
 686         return skb_put_zero(skb, NLA_ALIGN(attrlen));
 687 }
 688 EXPORT_SYMBOL(__nla_reserve_nohdr);
 689
 690 /**
 691  * nla_reserve - reserve room for attribute on the skb
 692  * @skb: socket buffer to reserve room on
 693  * @attrtype: attribute type
 694  * @attrlen: length of attribute payload
 695  *
 696  * Adds a netlink attribute header to a socket buffer and reserves
 697  * room for the payload but does not copy it.
 698  *
 699  * Returns NULL if the tailroom of the skb is insufficient to store
 700  * the attribute header and payload.
 701  */
 702 struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
 703 {
 704         if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
 705                 return NULL;
 706
 707         return __nla_reserve(skb, attrtype, attrlen);
 708 }
 709 EXPORT_SYMBOL(nla_reserve);
 710
 711 /**
 712  * nla_reserve_64bit - reserve room for attribute on the skb and align it
 713  * @skb: socket buffer to reserve room on
 714  * @attrtype: attribute type
 715  * @attrlen: length of attribute payload
 716  * @padattr: attribute type for the padding
 717  *
 718  * Adds a netlink attribute header to a socket buffer and reserves
 719  * room for the payload but does not copy it. It also ensure that this
 720  * attribute will have a 64-bit aligned nla_data() area.
 721  *
 722  * Returns NULL if the tailroom of the skb is insufficient to store
 723  * the attribute header and payload.
 724  */
 725 struct nlattr *nla_reserve_64bit(struct sk_buff *skb, int attrtype, int attrlen,
 726                                  int padattr)
 727 {
 728         size_t len;
 729
 730         if (nla_need_padding_for_64bit(skb))
 731                 len = nla_total_size_64bit(attrlen);
 732         else
 733                 len = nla_total_size(attrlen);
 734         if (unlikely(skb_tailroom(skb) < len))
 735                 return NULL;
 736
 737         return __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
 738 }
 739 EXPORT_SYMBOL(nla_reserve_64bit);
 740
 741 /**
 742  * nla_reserve_nohdr - reserve room for attribute without header
 743  * @skb: socket buffer to reserve room on
 744  * @attrlen: length of attribute payload
 745  *
 746  * Reserves room for attribute payload without a header.
 747  *
 748  * Returns NULL if the tailroom of the skb is insufficient to store
 749  * the attribute payload.
 750  */
 751 void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
 752 {
 753         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
 754                 return NULL;
 755
 756         return __nla_reserve_nohdr(skb, attrlen);
 757 }
 758 EXPORT_SYMBOL(nla_reserve_nohdr);
 759
 760 /**
 761  * __nla_put - Add a netlink attribute to a socket buffer
 762  * @skb: socket buffer to add attribute to
 763  * @attrtype: attribute type
 764  * @attrlen: length of attribute payload
 765  * @data: head of attribute payload
 766  *
 767  * The caller is responsible to ensure that the skb provides enough
 768  * tailroom for the attribute header and payload.
 769  */
 770 void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
 771                              const void *data)
 772 {
 773         struct nlattr *nla;
 774
 775         nla = __nla_reserve(skb, attrtype, attrlen);
 776         memcpy(nla_data(nla), data, attrlen);
 777 }
 778 EXPORT_SYMBOL(__nla_put);
 779
 780 /**
 781  * __nla_put_64bit - Add a netlink attribute to a socket buffer and align it
 782  * @skb: socket buffer to add attribute to
 783  * @attrtype: attribute type
 784  * @attrlen: length of attribute payload
 785  * @data: head of attribute payload
 786  * @padattr: attribute type for the padding
 787  *
 788  * The caller is responsible to ensure that the skb provides enough
 789  * tailroom for the attribute header and payload.
 790  */
 791 void __nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
 792                      const void *data, int padattr)
 793 {
 794         struct nlattr *nla;
 795
 796         nla = __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
 797         memcpy(nla_data(nla), data, attrlen);
 798 }
 799 EXPORT_SYMBOL(__nla_put_64bit);
 800
 801 /**
 802  * __nla_put_nohdr - Add a netlink attribute without header
 803  * @skb: socket buffer to add attribute to
 804  * @attrlen: length of attribute payload
 805  * @data: head of attribute payload
 806  *
 807  * The caller is responsible to ensure that the skb provides enough
 808  * tailroom for the attribute payload.
 809  */
 810 void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
 811 {
 812         void *start;
 813
 814         start = __nla_reserve_nohdr(skb, attrlen);
 815         memcpy(start, data, attrlen);
 816 }
 817 EXPORT_SYMBOL(__nla_put_nohdr);
 818
 819 /**
 820  * nla_put - Add a netlink attribute to a socket buffer
 821  * @skb: socket buffer to add attribute to
 822  * @attrtype: attribute type
 823  * @attrlen: length of attribute payload
 824  * @data: head of attribute payload
 825  *
 826  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
 827  * the attribute header and payload.
 828  */
 829 int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
 830 {
 831         if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
 832                 return -EMSGSIZE;
 833
 834         __nla_put(skb, attrtype, attrlen, data);
 835         return 0;
 836 }
 837 EXPORT_SYMBOL(nla_put);
 838
 839 /**
 840  * nla_put_64bit - Add a netlink attribute to a socket buffer and align it
 841  * @skb: socket buffer to add attribute to
 842  * @attrtype: attribute type
 843  * @attrlen: length of attribute payload
 844  * @data: head of attribute payload
 845  * @padattr: attribute type for the padding
 846  *
 847  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
 848  * the attribute header and payload.
 849  */
 850 int nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
 851                   const void *data, int padattr)
 852 {
 853         size_t len;
 854
 855         if (nla_need_padding_for_64bit(skb))
 856                 len = nla_total_size_64bit(attrlen);
 857         else
 858                 len = nla_total_size(attrlen);
 859         if (unlikely(skb_tailroom(skb) < len))
 860                 return -EMSGSIZE;
 861
 862         __nla_put_64bit(skb, attrtype, attrlen, data, padattr);
 863         return 0;
 864 }
 865 EXPORT_SYMBOL(nla_put_64bit);
 866
 867 /**
 868  * nla_put_nohdr - Add a netlink attribute without header
 869  * @skb: socket buffer to add attribute to
 870  * @attrlen: length of attribute payload
 871  * @data: head of attribute payload
 872  *
 873  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
 874  * the attribute payload.
 875  */
 876 int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
 877 {
 878         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
 879                 return -EMSGSIZE;
 880
 881         __nla_put_nohdr(skb, attrlen, data);
 882         return 0;
 883 }
 884 EXPORT_SYMBOL(nla_put_nohdr);
 885
 886 /**
 887  * nla_append - Add a netlink attribute without header or padding
 888  * @skb: socket buffer to add attribute to
 889  * @attrlen: length of attribute payload
 890  * @data: head of attribute payload
 891  *
 892  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
 893  * the attribute payload.
 894  */
 895 int nla_append(struct sk_buff *skb, int attrlen, const void *data)
 896 {
 897         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
 898                 return -EMSGSIZE;
 899
 900         skb_put_data(skb, data, attrlen);
 901         return 0;
 902 }
 903 EXPORT_SYMBOL(nla_append);
 904 #endif