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/nospec.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/string.h>
  16 #include <linux/types.h>
  17 #include <net/netlink.h>
  18
  19 /* For these data types, attribute length should be exactly the given
  20  * size. However, to maintain compatibility with broken commands, if the
  21  * attribute length does not match the expected size a warning is emitted
  22  * to the user that the command is sending invalid data and needs to be fixed.
  23  */
  24 static const u8 nla_attr_len[NLA_TYPE_MAX+1] = {
  25         [NLA_U8]        = sizeof(u8),
  26         [NLA_U16]       = sizeof(u16),
  27         [NLA_U32]       = sizeof(u32),
  28         [NLA_U64]       = sizeof(u64),
  29         [NLA_S8]        = sizeof(s8),
  30         [NLA_S16]       = sizeof(s16),
  31         [NLA_S32]       = sizeof(s32),
  32         [NLA_S64]       = sizeof(s64),
  33 };
  34
  35 static const u8 nla_attr_minlen[NLA_TYPE_MAX+1] = {
  36         [NLA_U8]        = sizeof(u8),
  37         [NLA_U16]       = sizeof(u16),
  38         [NLA_U32]       = sizeof(u32),
  39         [NLA_U64]       = sizeof(u64),
  40         [NLA_MSECS]     = sizeof(u64),
  41         [NLA_NESTED]    = NLA_HDRLEN,
  42         [NLA_S8]        = sizeof(s8),
  43         [NLA_S16]       = sizeof(s16),
  44         [NLA_S32]       = sizeof(s32),
  45         [NLA_S64]       = sizeof(s64),
  46 };
  47
  48 /*
  49  * Nested policies might refer back to the original
  50  * policy in some cases, and userspace could try to
  51  * abuse that and recurse by nesting in the right
  52  * ways. Limit recursion to avoid this problem.
  53  */
  54 #define MAX_POLICY_RECURSION_DEPTH      10
  55
  56 static int __nla_validate_parse(const struct nlattr *head, int len, int maxtype,
  57                                 const struct nla_policy *policy,
  58                                 unsigned int validate,
  59                                 struct netlink_ext_ack *extack,
  60                                 struct nlattr **tb, unsigned int depth);
  61
  62 static int validate_nla_bitfield32(const struct nlattr *nla,
  63                                    const u32 valid_flags_mask)
  64 {
  65         const struct nla_bitfield32 *bf = nla_data(nla);
  66
  67         if (!valid_flags_mask)
  68                 return -EINVAL;
  69
  70         /*disallow invalid bit selector */
  71         if (bf->selector & ~valid_flags_mask)
  72                 return -EINVAL;
  73
  74         /*disallow invalid bit values */
  75         if (bf->value & ~valid_flags_mask)
  76                 return -EINVAL;
  77
  78         /*disallow valid bit values that are not selected*/
  79         if (bf->value & ~bf->selector)
  80                 return -EINVAL;
  81
  82         return 0;
  83 }
  84
  85 static int nla_validate_array(const struct nlattr *head, int len, int maxtype,
  86                               const struct nla_policy *policy,
  87                               struct netlink_ext_ack *extack,
  88                               unsigned int validate, unsigned int depth)
  89 {
  90         const struct nlattr *entry;
  91         int rem;
  92
  93         nla_for_each_attr(entry, head, len, rem) {
  94                 int ret;
  95
  96                 if (nla_len(entry) == 0)
  97                         continue;
  98
  99                 if (nla_len(entry) < NLA_HDRLEN) {
 100                         NL_SET_ERR_MSG_ATTR_POL(extack, entry, policy,
 101                                                 "Array element too short");
 102                         return -ERANGE;
 103                 }
 104
 105                 ret = __nla_validate_parse(nla_data(entry), nla_len(entry),
 106                                            maxtype, policy, validate, extack,
 107                                            NULL, depth + 1);
 108                 if (ret < 0)
 109                         return ret;
 110         }
 111
 112         return 0;
 113 }
 114
 115 void nla_get_range_unsigned(const struct nla_policy *pt,
 116                             struct netlink_range_validation *range)
 117 {
 118         WARN_ON_ONCE(pt->validation_type != NLA_VALIDATE_RANGE_PTR &&
 119                      (pt->min < 0 || pt->max < 0));
 120
 121         range->min = 0;
 122
 123         switch (pt->type) {
 124         case NLA_U8:
 125                 range->max = U8_MAX;
 126                 break;
 127         case NLA_U16:
 128         case NLA_BE16:
 129         case NLA_BINARY:
 130                 range->max = U16_MAX;
 131                 break;
 132         case NLA_U32:
 133         case NLA_BE32:
 134                 range->max = U32_MAX;
 135                 break;
 136         case NLA_U64:
 137         case NLA_MSECS:
 138                 range->max = U64_MAX;
 139                 break;
 140         default:
 141                 WARN_ON_ONCE(1);
 142                 return;
 143         }
 144
 145         switch (pt->validation_type) {
 146         case NLA_VALIDATE_RANGE:
 147         case NLA_VALIDATE_RANGE_WARN_TOO_LONG:
 148                 range->min = pt->min;
 149                 range->max = pt->max;
 150                 break;
 151         case NLA_VALIDATE_RANGE_PTR:
 152                 *range = *pt->range;
 153                 break;
 154         case NLA_VALIDATE_MIN:
 155                 range->min = pt->min;
 156                 break;
 157         case NLA_VALIDATE_MAX:
 158                 range->max = pt->max;
 159                 break;
 160         default:
 161                 break;
 162         }
 163 }
 164
 165 static int nla_validate_range_unsigned(const struct nla_policy *pt,
 166                                        const struct nlattr *nla,
 167                                        struct netlink_ext_ack *extack,
 168                                        unsigned int validate)
 169 {
 170         struct netlink_range_validation range;
 171         u64 value;
 172
 173         switch (pt->type) {
 174         case NLA_U8:
 175                 value = nla_get_u8(nla);
 176                 break;
 177         case NLA_U16:
 178                 value = nla_get_u16(nla);
 179                 break;
 180         case NLA_U32:
 181                 value = nla_get_u32(nla);
 182                 break;
 183         case NLA_U64:
 184                 value = nla_get_u64(nla);
 185                 break;
 186         case NLA_MSECS:
 187                 value = nla_get_u64(nla);
 188                 break;
 189         case NLA_BINARY:
 190                 value = nla_len(nla);
 191                 break;
 192         case NLA_BE16:
 193                 value = ntohs(nla_get_be16(nla));
 194                 break;
 195         case NLA_BE32:
 196                 value = ntohl(nla_get_be32(nla));
 197                 break;
 198         default:
 199                 return -EINVAL;
 200         }
 201
 202         nla_get_range_unsigned(pt, &range);
 203
 204         if (pt->validation_type == NLA_VALIDATE_RANGE_WARN_TOO_LONG &&
 205             pt->type == NLA_BINARY && value > range.max) {
 206                 pr_warn_ratelimited("netlink: '%s': attribute type %d has an invalid length.\n",
 207                                     current->comm, pt->type);
 208                 if (validate & NL_VALIDATE_STRICT_ATTRS) {
 209                         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 210                                                 "invalid attribute length");
 211                         return -EINVAL;
 212                 }
 213
 214                 /* this assumes min <= max (don't validate against min) */
 215                 return 0;
 216         }
 217
 218         if (value < range.min || value > range.max) {
 219                 bool binary = pt->type == NLA_BINARY;
 220
 221                 if (binary)
 222                         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 223                                                 "binary attribute size out of range");
 224                 else
 225                         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 226                                                 "integer out of range");
 227
 228                 return -ERANGE;
 229         }
 230
 231         return 0;
 232 }
 233
 234 void nla_get_range_signed(const struct nla_policy *pt,
 235                           struct netlink_range_validation_signed *range)
 236 {
 237         switch (pt->type) {
 238         case NLA_S8:
 239                 range->min = S8_MIN;
 240                 range->max = S8_MAX;
 241                 break;
 242         case NLA_S16:
 243                 range->min = S16_MIN;
 244                 range->max = S16_MAX;
 245                 break;
 246         case NLA_S32:
 247                 range->min = S32_MIN;
 248                 range->max = S32_MAX;
 249                 break;
 250         case NLA_S64:
 251                 range->min = S64_MIN;
 252                 range->max = S64_MAX;
 253                 break;
 254         default:
 255                 WARN_ON_ONCE(1);
 256                 return;
 257         }
 258
 259         switch (pt->validation_type) {
 260         case NLA_VALIDATE_RANGE:
 261                 range->min = pt->min;
 262                 range->max = pt->max;
 263                 break;
 264         case NLA_VALIDATE_RANGE_PTR:
 265                 *range = *pt->range_signed;
 266                 break;
 267         case NLA_VALIDATE_MIN:
 268                 range->min = pt->min;
 269                 break;
 270         case NLA_VALIDATE_MAX:
 271                 range->max = pt->max;
 272                 break;
 273         default:
 274                 break;
 275         }
 276 }
 277
 278 static int nla_validate_int_range_signed(const struct nla_policy *pt,
 279                                          const struct nlattr *nla,
 280                                          struct netlink_ext_ack *extack)
 281 {
 282         struct netlink_range_validation_signed range;
 283         s64 value;
 284
 285         switch (pt->type) {
 286         case NLA_S8:
 287                 value = nla_get_s8(nla);
 288                 break;
 289         case NLA_S16:
 290                 value = nla_get_s16(nla);
 291                 break;
 292         case NLA_S32:
 293                 value = nla_get_s32(nla);
 294                 break;
 295         case NLA_S64:
 296                 value = nla_get_s64(nla);
 297                 break;
 298         default:
 299                 return -EINVAL;
 300         }
 301
 302         nla_get_range_signed(pt, &range);
 303
 304         if (value < range.min || value > range.max) {
 305                 NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 306                                         "integer out of range");
 307                 return -ERANGE;
 308         }
 309
 310         return 0;
 311 }
 312
 313 static int nla_validate_int_range(const struct nla_policy *pt,
 314                                   const struct nlattr *nla,
 315                                   struct netlink_ext_ack *extack,
 316                                   unsigned int validate)
 317 {
 318         switch (pt->type) {
 319         case NLA_U8:
 320         case NLA_U16:
 321         case NLA_U32:
 322         case NLA_U64:
 323         case NLA_MSECS:
 324         case NLA_BINARY:
 325         case NLA_BE16:
 326         case NLA_BE32:
 327                 return nla_validate_range_unsigned(pt, nla, extack, validate);
 328         case NLA_S8:
 329         case NLA_S16:
 330         case NLA_S32:
 331         case NLA_S64:
 332                 return nla_validate_int_range_signed(pt, nla, extack);
 333         default:
 334                 WARN_ON(1);
 335                 return -EINVAL;
 336         }
 337 }
 338
 339 static int nla_validate_mask(const struct nla_policy *pt,
 340                              const struct nlattr *nla,
 341                              struct netlink_ext_ack *extack)
 342 {
 343         u64 value;
 344
 345         switch (pt->type) {
 346         case NLA_U8:
 347                 value = nla_get_u8(nla);
 348                 break;
 349         case NLA_U16:
 350                 value = nla_get_u16(nla);
 351                 break;
 352         case NLA_U32:
 353                 value = nla_get_u32(nla);
 354                 break;
 355         case NLA_U64:
 356                 value = nla_get_u64(nla);
 357                 break;
 358         case NLA_BE16:
 359                 value = ntohs(nla_get_be16(nla));
 360                 break;
 361         case NLA_BE32:
 362                 value = ntohl(nla_get_be32(nla));
 363                 break;
 364         default:
 365                 return -EINVAL;
 366         }
 367
 368         if (value & ~(u64)pt->mask) {
 369                 NL_SET_ERR_MSG_ATTR(extack, nla, "reserved bit set");
 370                 return -EINVAL;
 371         }
 372
 373         return 0;
 374 }
 375
 376 static int validate_nla(const struct nlattr *nla, int maxtype,
 377                         const struct nla_policy *policy, unsigned int validate,
 378                         struct netlink_ext_ack *extack, unsigned int depth)
 379 {
 380         u16 strict_start_type = policy[0].strict_start_type;
 381         const struct nla_policy *pt;
 382         int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
 383         int err = -ERANGE;
 384
 385         if (strict_start_type && type >= strict_start_type)
 386                 validate |= NL_VALIDATE_STRICT;
 387
 388         if (type <= 0 || type > maxtype)
 389                 return 0;
 390
 391         type = array_index_nospec(type, maxtype + 1);
 392         pt = &policy[type];
 393
 394         BUG_ON(pt->type > NLA_TYPE_MAX);
 395
 396         if (nla_attr_len[pt->type] && attrlen != nla_attr_len[pt->type]) {
 397                 pr_warn_ratelimited("netlink: '%s': attribute type %d has an invalid length.\n",
 398                                     current->comm, type);
 399                 if (validate & NL_VALIDATE_STRICT_ATTRS) {
 400                         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 401                                                 "invalid attribute length");
 402                         return -EINVAL;
 403                 }
 404         }
 405
 406         if (validate & NL_VALIDATE_NESTED) {
 407                 if ((pt->type == NLA_NESTED || pt->type == NLA_NESTED_ARRAY) &&
 408                     !(nla->nla_type & NLA_F_NESTED)) {
 409                         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 410                                                 "NLA_F_NESTED is missing");
 411                         return -EINVAL;
 412                 }
 413                 if (pt->type != NLA_NESTED && pt->type != NLA_NESTED_ARRAY &&
 414                     pt->type != NLA_UNSPEC && (nla->nla_type & NLA_F_NESTED)) {
 415                         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 416                                                 "NLA_F_NESTED not expected");
 417                         return -EINVAL;
 418                 }
 419         }
 420
 421         switch (pt->type) {
 422         case NLA_REJECT:
 423                 if (extack && pt->reject_message) {
 424                         NL_SET_BAD_ATTR(extack, nla);
 425                         extack->_msg = pt->reject_message;
 426                         return -EINVAL;
 427                 }
 428                 err = -EINVAL;
 429                 goto out_err;
 430
 431         case NLA_FLAG:
 432                 if (attrlen > 0)
 433                         goto out_err;
 434                 break;
 435
 436         case NLA_BITFIELD32:
 437                 if (attrlen != sizeof(struct nla_bitfield32))
 438                         goto out_err;
 439
 440                 err = validate_nla_bitfield32(nla, pt->bitfield32_valid);
 441                 if (err)
 442                         goto out_err;
 443                 break;
 444
 445         case NLA_NUL_STRING:
 446                 if (pt->len)
 447                         minlen = min_t(int, attrlen, pt->len + 1);
 448                 else
 449                         minlen = attrlen;
 450
 451                 if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL) {
 452                         err = -EINVAL;
 453                         goto out_err;
 454                 }
 455                 fallthrough;
 456
 457         case NLA_STRING:
 458                 if (attrlen < 1)
 459                         goto out_err;
 460
 461                 if (pt->len) {
 462                         char *buf = nla_data(nla);
 463
 464                         if (buf[attrlen - 1] == '\0')
 465                                 attrlen--;
 466
 467                         if (attrlen > pt->len)
 468                                 goto out_err;
 469                 }
 470                 break;
 471
 472         case NLA_BINARY:
 473                 if (pt->len && attrlen > pt->len)
 474                         goto out_err;
 475                 break;
 476
 477         case NLA_NESTED:
 478                 /* a nested attributes is allowed to be empty; if its not,
 479                  * it must have a size of at least NLA_HDRLEN.
 480                  */
 481                 if (attrlen == 0)
 482                         break;
 483                 if (attrlen < NLA_HDRLEN)
 484                         goto out_err;
 485                 if (pt->nested_policy) {
 486                         err = __nla_validate_parse(nla_data(nla), nla_len(nla),
 487                                                    pt->len, pt->nested_policy,
 488                                                    validate, extack, NULL,
 489                                                    depth + 1);
 490                         if (err < 0) {
 491                                 /*
 492                                  * return directly to preserve the inner
 493                                  * error message/attribute pointer
 494                                  */
 495                                 return err;
 496                         }
 497                 }
 498                 break;
 499         case NLA_NESTED_ARRAY:
 500                 /* a nested array attribute is allowed to be empty; if its not,
 501                  * it must have a size of at least NLA_HDRLEN.
 502                  */
 503                 if (attrlen == 0)
 504                         break;
 505                 if (attrlen < NLA_HDRLEN)
 506                         goto out_err;
 507                 if (pt->nested_policy) {
 508                         int err;
 509
 510                         err = nla_validate_array(nla_data(nla), nla_len(nla),
 511                                                  pt->len, pt->nested_policy,
 512                                                  extack, validate, depth);
 513                         if (err < 0) {
 514                                 /*
 515                                  * return directly to preserve the inner
 516                                  * error message/attribute pointer
 517                                  */
 518                                 return err;
 519                         }
 520                 }
 521                 break;
 522
 523         case NLA_UNSPEC:
 524                 if (validate & NL_VALIDATE_UNSPEC) {
 525                         NL_SET_ERR_MSG_ATTR(extack, nla,
 526                                             "Unsupported attribute");
 527                         return -EINVAL;
 528                 }
 529                 if (attrlen < pt->len)
 530                         goto out_err;
 531                 break;
 532
 533         default:
 534                 if (pt->len)
 535                         minlen = pt->len;
 536                 else
 537                         minlen = nla_attr_minlen[pt->type];
 538
 539                 if (attrlen < minlen)
 540                         goto out_err;
 541         }
 542
 543         /* further validation */
 544         switch (pt->validation_type) {
 545         case NLA_VALIDATE_NONE:
 546                 /* nothing to do */
 547                 break;
 548         case NLA_VALIDATE_RANGE_PTR:
 549         case NLA_VALIDATE_RANGE:
 550         case NLA_VALIDATE_RANGE_WARN_TOO_LONG:
 551         case NLA_VALIDATE_MIN:
 552         case NLA_VALIDATE_MAX:
 553                 err = nla_validate_int_range(pt, nla, extack, validate);
 554                 if (err)
 555                         return err;
 556                 break;
 557         case NLA_VALIDATE_MASK:
 558                 err = nla_validate_mask(pt, nla, extack);
 559                 if (err)
 560                         return err;
 561                 break;
 562         case NLA_VALIDATE_FUNCTION:
 563                 if (pt->validate) {
 564                         err = pt->validate(nla, extack);
 565                         if (err)
 566                                 return err;
 567                 }
 568                 break;
 569         }
 570
 571         return 0;
 572 out_err:
 573         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 574                                 "Attribute failed policy validation");
 575         return err;
 576 }
 577
 578 static int __nla_validate_parse(const struct nlattr *head, int len, int maxtype,
 579                                 const struct nla_policy *policy,
 580                                 unsigned int validate,
 581                                 struct netlink_ext_ack *extack,
 582                                 struct nlattr **tb, unsigned int depth)
 583 {
 584         const struct nlattr *nla;
 585         int rem;
 586
 587         if (depth >= MAX_POLICY_RECURSION_DEPTH) {
 588                 NL_SET_ERR_MSG(extack,
 589                                "allowed policy recursion depth exceeded");
 590                 return -EINVAL;
 591         }
 592
 593         if (tb)
 594                 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
 595
 596         nla_for_each_attr(nla, head, len, rem) {
 597                 u16 type = nla_type(nla);
 598
 599                 if (type == 0 || type > maxtype) {
 600                         if (validate & NL_VALIDATE_MAXTYPE) {
 601                                 NL_SET_ERR_MSG_ATTR(extack, nla,
 602                                                     "Unknown attribute type");
 603                                 return -EINVAL;
 604                         }
 605                         continue;
 606                 }
 607                 type = array_index_nospec(type, maxtype + 1);
 608                 if (policy) {
 609                         int err = validate_nla(nla, maxtype, policy,
 610                                                validate, extack, depth);
 611
 612                         if (err < 0)
 613                                 return err;
 614                 }
 615
 616                 if (tb)
 617                         tb[type] = (struct nlattr *)nla;
 618         }
 619
 620         if (unlikely(rem > 0)) {
 621                 pr_warn_ratelimited("netlink: %d bytes leftover after parsing attributes in process `%s'.\n",
 622                                     rem, current->comm);
 623                 NL_SET_ERR_MSG(extack, "bytes leftover after parsing attributes");
 624                 if (validate & NL_VALIDATE_TRAILING)
 625                         return -EINVAL;
 626         }
 627
 628         return 0;
 629 }
 630
 631 /**
 632  * __nla_validate - Validate a stream of attributes
 633  * @head: head of attribute stream
 634  * @len: length of attribute stream
 635  * @maxtype: maximum attribute type to be expected
 636  * @policy: validation policy
 637  * @validate: validation strictness
 638  * @extack: extended ACK report struct
 639  *
 640  * Validates all attributes in the specified attribute stream against the
 641  * specified policy. Validation depends on the validate flags passed, see
 642  * &enum netlink_validation for more details on that.
 643  * See documentation of struct nla_policy for more details.
 644  *
 645  * Returns 0 on success or a negative error code.
 646  */
 647 int __nla_validate(const struct nlattr *head, int len, int maxtype,
 648                    const struct nla_policy *policy, unsigned int validate,
 649                    struct netlink_ext_ack *extack)
 650 {
 651         return __nla_validate_parse(head, len, maxtype, policy, validate,
 652                                     extack, NULL, 0);
 653 }
 654 EXPORT_SYMBOL(__nla_validate);
 655
 656 /**
 657  * nla_policy_len - Determine the max. length of a policy
 658  * @p: policy to use
 659  * @n: number of policies
 660  *
 661  * Determines the max. length of the policy.  It is currently used
 662  * to allocated Netlink buffers roughly the size of the actual
 663  * message.
 664  *
 665  * Returns 0 on success or a negative error code.
 666  */
 667 int
 668 nla_policy_len(const struct nla_policy *p, int n)
 669 {
 670         int i, len = 0;
 671
 672         for (i = 0; i < n; i++, p++) {
 673                 if (p->len)
 674                         len += nla_total_size(p->len);
 675                 else if (nla_attr_len[p->type])
 676                         len += nla_total_size(nla_attr_len[p->type]);
 677                 else if (nla_attr_minlen[p->type])
 678                         len += nla_total_size(nla_attr_minlen[p->type]);
 679         }
 680
 681         return len;
 682 }
 683 EXPORT_SYMBOL(nla_policy_len);
 684
 685 /**
 686  * __nla_parse - Parse a stream of attributes into a tb buffer
 687  * @tb: destination array with maxtype+1 elements
 688  * @maxtype: maximum attribute type to be expected
 689  * @head: head of attribute stream
 690  * @len: length of attribute stream
 691  * @policy: validation policy
 692  * @validate: validation strictness
 693  * @extack: extended ACK pointer
 694  *
 695  * Parses a stream of attributes and stores a pointer to each attribute in
 696  * the tb array accessible via the attribute type.
 697  * Validation is controlled by the @validate parameter.
 698  *
 699  * Returns 0 on success or a negative error code.
 700  */
 701 int __nla_parse(struct nlattr **tb, int maxtype,
 702                 const struct nlattr *head, int len,
 703                 const struct nla_policy *policy, unsigned int validate,
 704                 struct netlink_ext_ack *extack)
 705 {
 706         return __nla_validate_parse(head, len, maxtype, policy, validate,
 707                                     extack, tb, 0);
 708 }
 709 EXPORT_SYMBOL(__nla_parse);
 710
 711 /**
 712  * nla_find - Find a specific attribute in a stream of attributes
 713  * @head: head of attribute stream
 714  * @len: length of attribute stream
 715  * @attrtype: type of attribute to look for
 716  *
 717  * Returns the first attribute in the stream matching the specified type.
 718  */
 719 struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype)
 720 {
 721         const struct nlattr *nla;
 722         int rem;
 723
 724         nla_for_each_attr(nla, head, len, rem)
 725                 if (nla_type(nla) == attrtype)
 726                         return (struct nlattr *)nla;
 727
 728         return NULL;
 729 }
 730 EXPORT_SYMBOL(nla_find);
 731
 732 /**
 733  * nla_strscpy - Copy string attribute payload into a sized buffer
 734  * @dst: Where to copy the string to.
 735  * @nla: Attribute to copy the string from.
 736  * @dstsize: Size of destination buffer.
 737  *
 738  * Copies at most dstsize - 1 bytes into the destination buffer.
 739  * Unlike strlcpy the destination buffer is always padded out.
 740  *
 741  * Return:
 742  * * srclen - Returns @nla length (not including the trailing %NUL).
 743  * * -E2BIG - If @dstsize is 0 or greater than U16_MAX or @nla length greater
 744  *            than @dstsize.
 745  */
 746 ssize_t nla_strscpy(char *dst, const struct nlattr *nla, size_t dstsize)
 747 {
 748         size_t srclen = nla_len(nla);
 749         char *src = nla_data(nla);
 750         ssize_t ret;
 751         size_t len;
 752
 753         if (dstsize == 0 || WARN_ON_ONCE(dstsize > U16_MAX))
 754                 return -E2BIG;
 755
 756         if (srclen > 0 && src[srclen - 1] == '\0')
 757                 srclen--;
 758
 759         if (srclen >= dstsize) {
 760                 len = dstsize - 1;
 761                 ret = -E2BIG;
 762         } else {
 763                 len = srclen;
 764                 ret = len;
 765         }
 766
 767         memcpy(dst, src, len);
 768         /* Zero pad end of dst. */
 769         memset(dst + len, 0, dstsize - len);
 770
 771         return ret;
 772 }
 773 EXPORT_SYMBOL(nla_strscpy);
 774
 775 /**
 776  * nla_strdup - Copy string attribute payload into a newly allocated buffer
 777  * @nla: attribute to copy the string from
 778  * @flags: the type of memory to allocate (see kmalloc).
 779  *
 780  * Returns a pointer to the allocated buffer or NULL on error.
 781  */
 782 char *nla_strdup(const struct nlattr *nla, gfp_t flags)
 783 {
 784         size_t srclen = nla_len(nla);
 785         char *src = nla_data(nla), *dst;
 786
 787         if (srclen > 0 && src[srclen - 1] == '\0')
 788                 srclen--;
 789
 790         dst = kmalloc(srclen + 1, flags);
 791         if (dst != NULL) {
 792                 memcpy(dst, src, srclen);
 793                 dst[srclen] = '\0';
 794         }
 795         return dst;
 796 }
 797 EXPORT_SYMBOL(nla_strdup);
 798
 799 /**
 800  * nla_memcpy - Copy a netlink attribute into another memory area
 801  * @dest: where to copy to memcpy
 802  * @src: netlink attribute to copy from
 803  * @count: size of the destination area
 804  *
 805  * Note: The number of bytes copied is limited by the length of
 806  *       attribute's payload. memcpy
 807  *
 808  * Returns the number of bytes copied.
 809  */
 810 int nla_memcpy(void *dest, const struct nlattr *src, int count)
 811 {
 812         int minlen = min_t(int, count, nla_len(src));
 813
 814         memcpy(dest, nla_data(src), minlen);
 815         if (count > minlen)
 816                 memset(dest + minlen, 0, count - minlen);
 817
 818         return minlen;
 819 }
 820 EXPORT_SYMBOL(nla_memcpy);
 821
 822 /**
 823  * nla_memcmp - Compare an attribute with sized memory area
 824  * @nla: netlink attribute
 825  * @data: memory area
 826  * @size: size of memory area
 827  */
 828 int nla_memcmp(const struct nlattr *nla, const void *data,
 829                              size_t size)
 830 {
 831         int d = nla_len(nla) - size;
 832
 833         if (d == 0)
 834                 d = memcmp(nla_data(nla), data, size);
 835
 836         return d;
 837 }
 838 EXPORT_SYMBOL(nla_memcmp);
 839
 840 /**
 841  * nla_strcmp - Compare a string attribute against a string
 842  * @nla: netlink string attribute
 843  * @str: another string
 844  */
 845 int nla_strcmp(const struct nlattr *nla, const char *str)
 846 {
 847         int len = strlen(str);
 848         char *buf = nla_data(nla);
 849         int attrlen = nla_len(nla);
 850         int d;
 851
 852         while (attrlen > 0 && buf[attrlen - 1] == '\0')
 853                 attrlen--;
 854
 855         d = attrlen - len;
 856         if (d == 0)
 857                 d = memcmp(nla_data(nla), str, len);
 858
 859         return d;
 860 }
 861 EXPORT_SYMBOL(nla_strcmp);
 862
 863 #ifdef CONFIG_NET
 864 /**
 865  * __nla_reserve - reserve room for attribute on the skb
 866  * @skb: socket buffer to reserve room on
 867  * @attrtype: attribute type
 868  * @attrlen: length of attribute payload
 869  *
 870  * Adds a netlink attribute header to a socket buffer and reserves
 871  * room for the payload but does not copy it.
 872  *
 873  * The caller is responsible to ensure that the skb provides enough
 874  * tailroom for the attribute header and payload.
 875  */
 876 struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
 877 {
 878         struct nlattr *nla;
 879
 880         nla = skb_put(skb, nla_total_size(attrlen));
 881         nla->nla_type = attrtype;
 882         nla->nla_len = nla_attr_size(attrlen);
 883
 884         memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
 885
 886         return nla;
 887 }
 888 EXPORT_SYMBOL(__nla_reserve);
 889
 890 /**
 891  * __nla_reserve_64bit - reserve room for attribute on the skb and align it
 892  * @skb: socket buffer to reserve room on
 893  * @attrtype: attribute type
 894  * @attrlen: length of attribute payload
 895  * @padattr: attribute type for the padding
 896  *
 897  * Adds a netlink attribute header to a socket buffer and reserves
 898  * room for the payload but does not copy it. It also ensure that this
 899  * attribute will have a 64-bit aligned nla_data() area.
 900  *
 901  * The caller is responsible to ensure that the skb provides enough
 902  * tailroom for the attribute header and payload.
 903  */
 904 struct nlattr *__nla_reserve_64bit(struct sk_buff *skb, int attrtype,
 905                                    int attrlen, int padattr)
 906 {
 907         nla_align_64bit(skb, padattr);
 908
 909         return __nla_reserve(skb, attrtype, attrlen);
 910 }
 911 EXPORT_SYMBOL(__nla_reserve_64bit);
 912
 913 /**
 914  * __nla_reserve_nohdr - reserve room for attribute without header
 915  * @skb: socket buffer to reserve room on
 916  * @attrlen: length of attribute payload
 917  *
 918  * Reserves room for attribute payload without a header.
 919  *
 920  * The caller is responsible to ensure that the skb provides enough
 921  * tailroom for the payload.
 922  */
 923 void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
 924 {
 925         return skb_put_zero(skb, NLA_ALIGN(attrlen));
 926 }
 927 EXPORT_SYMBOL(__nla_reserve_nohdr);
 928
 929 /**
 930  * nla_reserve - reserve room for attribute on the skb
 931  * @skb: socket buffer to reserve room on
 932  * @attrtype: attribute type
 933  * @attrlen: length of attribute payload
 934  *
 935  * Adds a netlink attribute header to a socket buffer and reserves
 936  * room for the payload but does not copy it.
 937  *
 938  * Returns NULL if the tailroom of the skb is insufficient to store
 939  * the attribute header and payload.
 940  */
 941 struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
 942 {
 943         if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
 944                 return NULL;
 945
 946         return __nla_reserve(skb, attrtype, attrlen);
 947 }
 948 EXPORT_SYMBOL(nla_reserve);
 949
 950 /**
 951  * nla_reserve_64bit - reserve room for attribute on the skb and align it
 952  * @skb: socket buffer to reserve room on
 953  * @attrtype: attribute type
 954  * @attrlen: length of attribute payload
 955  * @padattr: attribute type for the padding
 956  *
 957  * Adds a netlink attribute header to a socket buffer and reserves
 958  * room for the payload but does not copy it. It also ensure that this
 959  * attribute will have a 64-bit aligned nla_data() area.
 960  *
 961  * Returns NULL if the tailroom of the skb is insufficient to store
 962  * the attribute header and payload.
 963  */
 964 struct nlattr *nla_reserve_64bit(struct sk_buff *skb, int attrtype, int attrlen,
 965                                  int padattr)
 966 {
 967         size_t len;
 968
 969         if (nla_need_padding_for_64bit(skb))
 970                 len = nla_total_size_64bit(attrlen);
 971         else
 972                 len = nla_total_size(attrlen);
 973         if (unlikely(skb_tailroom(skb) < len))
 974                 return NULL;
 975
 976         return __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
 977 }
 978 EXPORT_SYMBOL(nla_reserve_64bit);
 979
 980 /**
 981  * nla_reserve_nohdr - reserve room for attribute without header
 982  * @skb: socket buffer to reserve room on
 983  * @attrlen: length of attribute payload
 984  *
 985  * Reserves room for attribute payload without a header.
 986  *
 987  * Returns NULL if the tailroom of the skb is insufficient to store
 988  * the attribute payload.
 989  */
 990 void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
 991 {
 992         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
 993                 return NULL;
 994
 995         return __nla_reserve_nohdr(skb, attrlen);
 996 }
 997 EXPORT_SYMBOL(nla_reserve_nohdr);
 998
 999 /**
1000  * __nla_put - Add a netlink attribute to a socket buffer
1001  * @skb: socket buffer to add attribute to
1002  * @attrtype: attribute type
1003  * @attrlen: length of attribute payload
1004  * @data: head of attribute payload
1005  *
1006  * The caller is responsible to ensure that the skb provides enough
1007  * tailroom for the attribute header and payload.
1008  */
1009 void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
1010                              const void *data)
1011 {
1012         struct nlattr *nla;
1013
1014         nla = __nla_reserve(skb, attrtype, attrlen);
1015         memcpy(nla_data(nla), data, attrlen);
1016 }
1017 EXPORT_SYMBOL(__nla_put);
1018
1019 /**
1020  * __nla_put_64bit - Add a netlink attribute to a socket buffer and align it
1021  * @skb: socket buffer to add attribute to
1022  * @attrtype: attribute type
1023  * @attrlen: length of attribute payload
1024  * @data: head of attribute payload
1025  * @padattr: attribute type for the padding
1026  *
1027  * The caller is responsible to ensure that the skb provides enough
1028  * tailroom for the attribute header and payload.
1029  */
1030 void __nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
1031                      const void *data, int padattr)
1032 {
1033         struct nlattr *nla;
1034
1035         nla = __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
1036         memcpy(nla_data(nla), data, attrlen);
1037 }
1038 EXPORT_SYMBOL(__nla_put_64bit);
1039
1040 /**
1041  * __nla_put_nohdr - Add a netlink attribute without header
1042  * @skb: socket buffer to add attribute to
1043  * @attrlen: length of attribute payload
1044  * @data: head of attribute payload
1045  *
1046  * The caller is responsible to ensure that the skb provides enough
1047  * tailroom for the attribute payload.
1048  */
1049 void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
1050 {
1051         void *start;
1052
1053         start = __nla_reserve_nohdr(skb, attrlen);
1054         memcpy(start, data, attrlen);
1055 }
1056 EXPORT_SYMBOL(__nla_put_nohdr);
1057
1058 /**
1059  * nla_put - Add a netlink attribute to a socket buffer
1060  * @skb: socket buffer to add attribute to
1061  * @attrtype: attribute type
1062  * @attrlen: length of attribute payload
1063  * @data: head of attribute payload
1064  *
1065  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
1066  * the attribute header and payload.
1067  */
1068 int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
1069 {
1070         if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
1071                 return -EMSGSIZE;
1072
1073         __nla_put(skb, attrtype, attrlen, data);
1074         return 0;
1075 }
1076 EXPORT_SYMBOL(nla_put);
1077
1078 /**
1079  * nla_put_64bit - Add a netlink attribute to a socket buffer and align it
1080  * @skb: socket buffer to add attribute to
1081  * @attrtype: attribute type
1082  * @attrlen: length of attribute payload
1083  * @data: head of attribute payload
1084  * @padattr: attribute type for the padding
1085  *
1086  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
1087  * the attribute header and payload.
1088  */
1089 int nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
1090                   const void *data, int padattr)
1091 {
1092         size_t len;
1093
1094         if (nla_need_padding_for_64bit(skb))
1095                 len = nla_total_size_64bit(attrlen);
1096         else
1097                 len = nla_total_size(attrlen);
1098         if (unlikely(skb_tailroom(skb) < len))
1099                 return -EMSGSIZE;
1100
1101         __nla_put_64bit(skb, attrtype, attrlen, data, padattr);
1102         return 0;
1103 }
1104 EXPORT_SYMBOL(nla_put_64bit);
1105
1106 /**
1107  * nla_put_nohdr - Add a netlink attribute without header
1108  * @skb: socket buffer to add attribute to
1109  * @attrlen: length of attribute payload
1110  * @data: head of attribute payload
1111  *
1112  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
1113  * the attribute payload.
1114  */
1115 int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
1116 {
1117         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
1118                 return -EMSGSIZE;
1119
1120         __nla_put_nohdr(skb, attrlen, data);
1121         return 0;
1122 }
1123 EXPORT_SYMBOL(nla_put_nohdr);
1124
1125 /**
1126  * nla_append - Add a netlink attribute without header or padding
1127  * @skb: socket buffer to add attribute to
1128  * @attrlen: length of attribute payload
1129  * @data: head of attribute payload
1130  *
1131  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
1132  * the attribute payload.
1133  */
1134 int nla_append(struct sk_buff *skb, int attrlen, const void *data)
1135 {
1136         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
1137                 return -EMSGSIZE;
1138
1139         skb_put_data(skb, data, attrlen);
1140         return 0;
1141 }
1142 EXPORT_SYMBOL(nla_append);
1143 #endif