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         default:
 359                 return -EINVAL;
 360         }
 361
 362         if (value & ~(u64)pt->mask) {
 363                 NL_SET_ERR_MSG_ATTR(extack, nla, "reserved bit set");
 364                 return -EINVAL;
 365         }
 366
 367         return 0;
 368 }
 369
 370 static int validate_nla(const struct nlattr *nla, int maxtype,
 371                         const struct nla_policy *policy, unsigned int validate,
 372                         struct netlink_ext_ack *extack, unsigned int depth)
 373 {
 374         u16 strict_start_type = policy[0].strict_start_type;
 375         const struct nla_policy *pt;
 376         int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
 377         int err = -ERANGE;
 378
 379         if (strict_start_type && type >= strict_start_type)
 380                 validate |= NL_VALIDATE_STRICT;
 381
 382         if (type <= 0 || type > maxtype)
 383                 return 0;
 384
 385         type = array_index_nospec(type, maxtype + 1);
 386         pt = &policy[type];
 387
 388         BUG_ON(pt->type > NLA_TYPE_MAX);
 389
 390         if (nla_attr_len[pt->type] && attrlen != nla_attr_len[pt->type]) {
 391                 pr_warn_ratelimited("netlink: '%s': attribute type %d has an invalid length.\n",
 392                                     current->comm, type);
 393                 if (validate & NL_VALIDATE_STRICT_ATTRS) {
 394                         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 395                                                 "invalid attribute length");
 396                         return -EINVAL;
 397                 }
 398         }
 399
 400         if (validate & NL_VALIDATE_NESTED) {
 401                 if ((pt->type == NLA_NESTED || pt->type == NLA_NESTED_ARRAY) &&
 402                     !(nla->nla_type & NLA_F_NESTED)) {
 403                         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 404                                                 "NLA_F_NESTED is missing");
 405                         return -EINVAL;
 406                 }
 407                 if (pt->type != NLA_NESTED && pt->type != NLA_NESTED_ARRAY &&
 408                     pt->type != NLA_UNSPEC && (nla->nla_type & NLA_F_NESTED)) {
 409                         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 410                                                 "NLA_F_NESTED not expected");
 411                         return -EINVAL;
 412                 }
 413         }
 414
 415         switch (pt->type) {
 416         case NLA_REJECT:
 417                 if (extack && pt->reject_message) {
 418                         NL_SET_BAD_ATTR(extack, nla);
 419                         extack->_msg = pt->reject_message;
 420                         return -EINVAL;
 421                 }
 422                 err = -EINVAL;
 423                 goto out_err;
 424
 425         case NLA_FLAG:
 426                 if (attrlen > 0)
 427                         goto out_err;
 428                 break;
 429
 430         case NLA_BITFIELD32:
 431                 if (attrlen != sizeof(struct nla_bitfield32))
 432                         goto out_err;
 433
 434                 err = validate_nla_bitfield32(nla, pt->bitfield32_valid);
 435                 if (err)
 436                         goto out_err;
 437                 break;
 438
 439         case NLA_NUL_STRING:
 440                 if (pt->len)
 441                         minlen = min_t(int, attrlen, pt->len + 1);
 442                 else
 443                         minlen = attrlen;
 444
 445                 if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL) {
 446                         err = -EINVAL;
 447                         goto out_err;
 448                 }
 449                 fallthrough;
 450
 451         case NLA_STRING:
 452                 if (attrlen < 1)
 453                         goto out_err;
 454
 455                 if (pt->len) {
 456                         char *buf = nla_data(nla);
 457
 458                         if (buf[attrlen - 1] == '\0')
 459                                 attrlen--;
 460
 461                         if (attrlen > pt->len)
 462                                 goto out_err;
 463                 }
 464                 break;
 465
 466         case NLA_BINARY:
 467                 if (pt->len && attrlen > pt->len)
 468                         goto out_err;
 469                 break;
 470
 471         case NLA_NESTED:
 472                 /* a nested attributes is allowed to be empty; if its not,
 473                  * it must have a size of at least NLA_HDRLEN.
 474                  */
 475                 if (attrlen == 0)
 476                         break;
 477                 if (attrlen < NLA_HDRLEN)
 478                         goto out_err;
 479                 if (pt->nested_policy) {
 480                         err = __nla_validate_parse(nla_data(nla), nla_len(nla),
 481                                                    pt->len, pt->nested_policy,
 482                                                    validate, extack, NULL,
 483                                                    depth + 1);
 484                         if (err < 0) {
 485                                 /*
 486                                  * return directly to preserve the inner
 487                                  * error message/attribute pointer
 488                                  */
 489                                 return err;
 490                         }
 491                 }
 492                 break;
 493         case NLA_NESTED_ARRAY:
 494                 /* a nested array attribute is allowed to be empty; if its not,
 495                  * it must have a size of at least NLA_HDRLEN.
 496                  */
 497                 if (attrlen == 0)
 498                         break;
 499                 if (attrlen < NLA_HDRLEN)
 500                         goto out_err;
 501                 if (pt->nested_policy) {
 502                         int err;
 503
 504                         err = nla_validate_array(nla_data(nla), nla_len(nla),
 505                                                  pt->len, pt->nested_policy,
 506                                                  extack, validate, depth);
 507                         if (err < 0) {
 508                                 /*
 509                                  * return directly to preserve the inner
 510                                  * error message/attribute pointer
 511                                  */
 512                                 return err;
 513                         }
 514                 }
 515                 break;
 516
 517         case NLA_UNSPEC:
 518                 if (validate & NL_VALIDATE_UNSPEC) {
 519                         NL_SET_ERR_MSG_ATTR(extack, nla,
 520                                             "Unsupported attribute");
 521                         return -EINVAL;
 522                 }
 523                 if (attrlen < pt->len)
 524                         goto out_err;
 525                 break;
 526
 527         default:
 528                 if (pt->len)
 529                         minlen = pt->len;
 530                 else
 531                         minlen = nla_attr_minlen[pt->type];
 532
 533                 if (attrlen < minlen)
 534                         goto out_err;
 535         }
 536
 537         /* further validation */
 538         switch (pt->validation_type) {
 539         case NLA_VALIDATE_NONE:
 540                 /* nothing to do */
 541                 break;
 542         case NLA_VALIDATE_RANGE_PTR:
 543         case NLA_VALIDATE_RANGE:
 544         case NLA_VALIDATE_RANGE_WARN_TOO_LONG:
 545         case NLA_VALIDATE_MIN:
 546         case NLA_VALIDATE_MAX:
 547                 err = nla_validate_int_range(pt, nla, extack, validate);
 548                 if (err)
 549                         return err;
 550                 break;
 551         case NLA_VALIDATE_MASK:
 552                 err = nla_validate_mask(pt, nla, extack);
 553                 if (err)
 554                         return err;
 555                 break;
 556         case NLA_VALIDATE_FUNCTION:
 557                 if (pt->validate) {
 558                         err = pt->validate(nla, extack);
 559                         if (err)
 560                                 return err;
 561                 }
 562                 break;
 563         }
 564
 565         return 0;
 566 out_err:
 567         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 568                                 "Attribute failed policy validation");
 569         return err;
 570 }
 571
 572 static int __nla_validate_parse(const struct nlattr *head, int len, int maxtype,
 573                                 const struct nla_policy *policy,
 574                                 unsigned int validate,
 575                                 struct netlink_ext_ack *extack,
 576                                 struct nlattr **tb, unsigned int depth)
 577 {
 578         const struct nlattr *nla;
 579         int rem;
 580
 581         if (depth >= MAX_POLICY_RECURSION_DEPTH) {
 582                 NL_SET_ERR_MSG(extack,
 583                                "allowed policy recursion depth exceeded");
 584                 return -EINVAL;
 585         }
 586
 587         if (tb)
 588                 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
 589
 590         nla_for_each_attr(nla, head, len, rem) {
 591                 u16 type = nla_type(nla);
 592
 593                 if (type == 0 || type > maxtype) {
 594                         if (validate & NL_VALIDATE_MAXTYPE) {
 595                                 NL_SET_ERR_MSG_ATTR(extack, nla,
 596                                                     "Unknown attribute type");
 597                                 return -EINVAL;
 598                         }
 599                         continue;
 600                 }
 601                 type = array_index_nospec(type, maxtype + 1);
 602                 if (policy) {
 603                         int err = validate_nla(nla, maxtype, policy,
 604                                                validate, extack, depth);
 605
 606                         if (err < 0)
 607                                 return err;
 608                 }
 609
 610                 if (tb)
 611                         tb[type] = (struct nlattr *)nla;
 612         }
 613
 614         if (unlikely(rem > 0)) {
 615                 pr_warn_ratelimited("netlink: %d bytes leftover after parsing attributes in process `%s'.\n",
 616                                     rem, current->comm);
 617                 NL_SET_ERR_MSG(extack, "bytes leftover after parsing attributes");
 618                 if (validate & NL_VALIDATE_TRAILING)
 619                         return -EINVAL;
 620         }
 621
 622         return 0;
 623 }
 624
 625 /**
 626  * __nla_validate - Validate a stream of attributes
 627  * @head: head of attribute stream
 628  * @len: length of attribute stream
 629  * @maxtype: maximum attribute type to be expected
 630  * @policy: validation policy
 631  * @validate: validation strictness
 632  * @extack: extended ACK report struct
 633  *
 634  * Validates all attributes in the specified attribute stream against the
 635  * specified policy. Validation depends on the validate flags passed, see
 636  * &enum netlink_validation for more details on that.
 637  * See documentation of struct nla_policy for more details.
 638  *
 639  * Returns 0 on success or a negative error code.
 640  */
 641 int __nla_validate(const struct nlattr *head, int len, int maxtype,
 642                    const struct nla_policy *policy, unsigned int validate,
 643                    struct netlink_ext_ack *extack)
 644 {
 645         return __nla_validate_parse(head, len, maxtype, policy, validate,
 646                                     extack, NULL, 0);
 647 }
 648 EXPORT_SYMBOL(__nla_validate);
 649
 650 /**
 651  * nla_policy_len - Determine the max. length of a policy
 652  * @p: policy to use
 653  * @n: number of policies
 654  *
 655  * Determines the max. length of the policy.  It is currently used
 656  * to allocated Netlink buffers roughly the size of the actual
 657  * message.
 658  *
 659  * Returns 0 on success or a negative error code.
 660  */
 661 int
 662 nla_policy_len(const struct nla_policy *p, int n)
 663 {
 664         int i, len = 0;
 665
 666         for (i = 0; i < n; i++, p++) {
 667                 if (p->len)
 668                         len += nla_total_size(p->len);
 669                 else if (nla_attr_len[p->type])
 670                         len += nla_total_size(nla_attr_len[p->type]);
 671                 else if (nla_attr_minlen[p->type])
 672                         len += nla_total_size(nla_attr_minlen[p->type]);
 673         }
 674
 675         return len;
 676 }
 677 EXPORT_SYMBOL(nla_policy_len);
 678
 679 /**
 680  * __nla_parse - Parse a stream of attributes into a tb buffer
 681  * @tb: destination array with maxtype+1 elements
 682  * @maxtype: maximum attribute type to be expected
 683  * @head: head of attribute stream
 684  * @len: length of attribute stream
 685  * @policy: validation policy
 686  * @validate: validation strictness
 687  * @extack: extended ACK pointer
 688  *
 689  * Parses a stream of attributes and stores a pointer to each attribute in
 690  * the tb array accessible via the attribute type.
 691  * Validation is controlled by the @validate parameter.
 692  *
 693  * Returns 0 on success or a negative error code.
 694  */
 695 int __nla_parse(struct nlattr **tb, int maxtype,
 696                 const struct nlattr *head, int len,
 697                 const struct nla_policy *policy, unsigned int validate,
 698                 struct netlink_ext_ack *extack)
 699 {
 700         return __nla_validate_parse(head, len, maxtype, policy, validate,
 701                                     extack, tb, 0);
 702 }
 703 EXPORT_SYMBOL(__nla_parse);
 704
 705 /**
 706  * nla_find - Find a specific attribute in a stream of attributes
 707  * @head: head of attribute stream
 708  * @len: length of attribute stream
 709  * @attrtype: type of attribute to look for
 710  *
 711  * Returns the first attribute in the stream matching the specified type.
 712  */
 713 struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype)
 714 {
 715         const struct nlattr *nla;
 716         int rem;
 717
 718         nla_for_each_attr(nla, head, len, rem)
 719                 if (nla_type(nla) == attrtype)
 720                         return (struct nlattr *)nla;
 721
 722         return NULL;
 723 }
 724 EXPORT_SYMBOL(nla_find);
 725
 726 /**
 727  * nla_strscpy - Copy string attribute payload into a sized buffer
 728  * @dst: Where to copy the string to.
 729  * @nla: Attribute to copy the string from.
 730  * @dstsize: Size of destination buffer.
 731  *
 732  * Copies at most dstsize - 1 bytes into the destination buffer.
 733  * Unlike strlcpy the destination buffer is always padded out.
 734  *
 735  * Return:
 736  * * srclen - Returns @nla length (not including the trailing %NUL).
 737  * * -E2BIG - If @dstsize is 0 or greater than U16_MAX or @nla length greater
 738  *            than @dstsize.
 739  */
 740 ssize_t nla_strscpy(char *dst, const struct nlattr *nla, size_t dstsize)
 741 {
 742         size_t srclen = nla_len(nla);
 743         char *src = nla_data(nla);
 744         ssize_t ret;
 745         size_t len;
 746
 747         if (dstsize == 0 || WARN_ON_ONCE(dstsize > U16_MAX))
 748                 return -E2BIG;
 749
 750         if (srclen > 0 && src[srclen - 1] == '\0')
 751                 srclen--;
 752
 753         if (srclen >= dstsize) {
 754                 len = dstsize - 1;
 755                 ret = -E2BIG;
 756         } else {
 757                 len = srclen;
 758                 ret = len;
 759         }
 760
 761         memcpy(dst, src, len);
 762         /* Zero pad end of dst. */
 763         memset(dst + len, 0, dstsize - len);
 764
 765         return ret;
 766 }
 767 EXPORT_SYMBOL(nla_strscpy);
 768
 769 /**
 770  * nla_strdup - Copy string attribute payload into a newly allocated buffer
 771  * @nla: attribute to copy the string from
 772  * @flags: the type of memory to allocate (see kmalloc).
 773  *
 774  * Returns a pointer to the allocated buffer or NULL on error.
 775  */
 776 char *nla_strdup(const struct nlattr *nla, gfp_t flags)
 777 {
 778         size_t srclen = nla_len(nla);
 779         char *src = nla_data(nla), *dst;
 780
 781         if (srclen > 0 && src[srclen - 1] == '\0')
 782                 srclen--;
 783
 784         dst = kmalloc(srclen + 1, flags);
 785         if (dst != NULL) {
 786                 memcpy(dst, src, srclen);
 787                 dst[srclen] = '\0';
 788         }
 789         return dst;
 790 }
 791 EXPORT_SYMBOL(nla_strdup);
 792
 793 /**
 794  * nla_memcpy - Copy a netlink attribute into another memory area
 795  * @dest: where to copy to memcpy
 796  * @src: netlink attribute to copy from
 797  * @count: size of the destination area
 798  *
 799  * Note: The number of bytes copied is limited by the length of
 800  *       attribute's payload. memcpy
 801  *
 802  * Returns the number of bytes copied.
 803  */
 804 int nla_memcpy(void *dest, const struct nlattr *src, int count)
 805 {
 806         int minlen = min_t(int, count, nla_len(src));
 807
 808         memcpy(dest, nla_data(src), minlen);
 809         if (count > minlen)
 810                 memset(dest + minlen, 0, count - minlen);
 811
 812         return minlen;
 813 }
 814 EXPORT_SYMBOL(nla_memcpy);
 815
 816 /**
 817  * nla_memcmp - Compare an attribute with sized memory area
 818  * @nla: netlink attribute
 819  * @data: memory area
 820  * @size: size of memory area
 821  */
 822 int nla_memcmp(const struct nlattr *nla, const void *data,
 823                              size_t size)
 824 {
 825         int d = nla_len(nla) - size;
 826
 827         if (d == 0)
 828                 d = memcmp(nla_data(nla), data, size);
 829
 830         return d;
 831 }
 832 EXPORT_SYMBOL(nla_memcmp);
 833
 834 /**
 835  * nla_strcmp - Compare a string attribute against a string
 836  * @nla: netlink string attribute
 837  * @str: another string
 838  */
 839 int nla_strcmp(const struct nlattr *nla, const char *str)
 840 {
 841         int len = strlen(str);
 842         char *buf = nla_data(nla);
 843         int attrlen = nla_len(nla);
 844         int d;
 845
 846         while (attrlen > 0 && buf[attrlen - 1] == '\0')
 847                 attrlen--;
 848
 849         d = attrlen - len;
 850         if (d == 0)
 851                 d = memcmp(nla_data(nla), str, len);
 852
 853         return d;
 854 }
 855 EXPORT_SYMBOL(nla_strcmp);
 856
 857 #ifdef CONFIG_NET
 858 /**
 859  * __nla_reserve - reserve room for attribute on the skb
 860  * @skb: socket buffer to reserve room on
 861  * @attrtype: attribute type
 862  * @attrlen: length of attribute payload
 863  *
 864  * Adds a netlink attribute header to a socket buffer and reserves
 865  * room for the payload but does not copy it.
 866  *
 867  * The caller is responsible to ensure that the skb provides enough
 868  * tailroom for the attribute header and payload.
 869  */
 870 struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
 871 {
 872         struct nlattr *nla;
 873
 874         nla = skb_put(skb, nla_total_size(attrlen));
 875         nla->nla_type = attrtype;
 876         nla->nla_len = nla_attr_size(attrlen);
 877
 878         memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
 879
 880         return nla;
 881 }
 882 EXPORT_SYMBOL(__nla_reserve);
 883
 884 /**
 885  * __nla_reserve_64bit - reserve room for attribute on the skb and align it
 886  * @skb: socket buffer to reserve room on
 887  * @attrtype: attribute type
 888  * @attrlen: length of attribute payload
 889  * @padattr: attribute type for the padding
 890  *
 891  * Adds a netlink attribute header to a socket buffer and reserves
 892  * room for the payload but does not copy it. It also ensure that this
 893  * attribute will have a 64-bit aligned nla_data() area.
 894  *
 895  * The caller is responsible to ensure that the skb provides enough
 896  * tailroom for the attribute header and payload.
 897  */
 898 struct nlattr *__nla_reserve_64bit(struct sk_buff *skb, int attrtype,
 899                                    int attrlen, int padattr)
 900 {
 901         nla_align_64bit(skb, padattr);
 902
 903         return __nla_reserve(skb, attrtype, attrlen);
 904 }
 905 EXPORT_SYMBOL(__nla_reserve_64bit);
 906
 907 /**
 908  * __nla_reserve_nohdr - reserve room for attribute without header
 909  * @skb: socket buffer to reserve room on
 910  * @attrlen: length of attribute payload
 911  *
 912  * Reserves room for attribute payload without a header.
 913  *
 914  * The caller is responsible to ensure that the skb provides enough
 915  * tailroom for the payload.
 916  */
 917 void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
 918 {
 919         return skb_put_zero(skb, NLA_ALIGN(attrlen));
 920 }
 921 EXPORT_SYMBOL(__nla_reserve_nohdr);
 922
 923 /**
 924  * nla_reserve - reserve room for attribute on the skb
 925  * @skb: socket buffer to reserve room on
 926  * @attrtype: attribute type
 927  * @attrlen: length of attribute payload
 928  *
 929  * Adds a netlink attribute header to a socket buffer and reserves
 930  * room for the payload but does not copy it.
 931  *
 932  * Returns NULL if the tailroom of the skb is insufficient to store
 933  * the attribute header and payload.
 934  */
 935 struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
 936 {
 937         if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
 938                 return NULL;
 939
 940         return __nla_reserve(skb, attrtype, attrlen);
 941 }
 942 EXPORT_SYMBOL(nla_reserve);
 943
 944 /**
 945  * nla_reserve_64bit - reserve room for attribute on the skb and align it
 946  * @skb: socket buffer to reserve room on
 947  * @attrtype: attribute type
 948  * @attrlen: length of attribute payload
 949  * @padattr: attribute type for the padding
 950  *
 951  * Adds a netlink attribute header to a socket buffer and reserves
 952  * room for the payload but does not copy it. It also ensure that this
 953  * attribute will have a 64-bit aligned nla_data() area.
 954  *
 955  * Returns NULL if the tailroom of the skb is insufficient to store
 956  * the attribute header and payload.
 957  */
 958 struct nlattr *nla_reserve_64bit(struct sk_buff *skb, int attrtype, int attrlen,
 959                                  int padattr)
 960 {
 961         size_t len;
 962
 963         if (nla_need_padding_for_64bit(skb))
 964                 len = nla_total_size_64bit(attrlen);
 965         else
 966                 len = nla_total_size(attrlen);
 967         if (unlikely(skb_tailroom(skb) < len))
 968                 return NULL;
 969
 970         return __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
 971 }
 972 EXPORT_SYMBOL(nla_reserve_64bit);
 973
 974 /**
 975  * nla_reserve_nohdr - reserve room for attribute without header
 976  * @skb: socket buffer to reserve room on
 977  * @attrlen: length of attribute payload
 978  *
 979  * Reserves room for attribute payload without a header.
 980  *
 981  * Returns NULL if the tailroom of the skb is insufficient to store
 982  * the attribute payload.
 983  */
 984 void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
 985 {
 986         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
 987                 return NULL;
 988
 989         return __nla_reserve_nohdr(skb, attrlen);
 990 }
 991 EXPORT_SYMBOL(nla_reserve_nohdr);
 992
 993 /**
 994  * __nla_put - Add a netlink attribute to a socket buffer
 995  * @skb: socket buffer to add attribute to
 996  * @attrtype: attribute type
 997  * @attrlen: length of attribute payload
 998  * @data: head of attribute payload
 999  *
1000  * The caller is responsible to ensure that the skb provides enough
1001  * tailroom for the attribute header and payload.
1002  */
1003 void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
1004                              const void *data)
1005 {
1006         struct nlattr *nla;
1007
1008         nla = __nla_reserve(skb, attrtype, attrlen);
1009         memcpy(nla_data(nla), data, attrlen);
1010 }
1011 EXPORT_SYMBOL(__nla_put);
1012
1013 /**
1014  * __nla_put_64bit - Add a netlink attribute to a socket buffer and align it
1015  * @skb: socket buffer to add attribute to
1016  * @attrtype: attribute type
1017  * @attrlen: length of attribute payload
1018  * @data: head of attribute payload
1019  * @padattr: attribute type for the padding
1020  *
1021  * The caller is responsible to ensure that the skb provides enough
1022  * tailroom for the attribute header and payload.
1023  */
1024 void __nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
1025                      const void *data, int padattr)
1026 {
1027         struct nlattr *nla;
1028
1029         nla = __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
1030         memcpy(nla_data(nla), data, attrlen);
1031 }
1032 EXPORT_SYMBOL(__nla_put_64bit);
1033
1034 /**
1035  * __nla_put_nohdr - Add a netlink attribute without header
1036  * @skb: socket buffer to add attribute to
1037  * @attrlen: length of attribute payload
1038  * @data: head of attribute payload
1039  *
1040  * The caller is responsible to ensure that the skb provides enough
1041  * tailroom for the attribute payload.
1042  */
1043 void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
1044 {
1045         void *start;
1046
1047         start = __nla_reserve_nohdr(skb, attrlen);
1048         memcpy(start, data, attrlen);
1049 }
1050 EXPORT_SYMBOL(__nla_put_nohdr);
1051
1052 /**
1053  * nla_put - Add a netlink attribute to a socket buffer
1054  * @skb: socket buffer to add attribute to
1055  * @attrtype: attribute type
1056  * @attrlen: length of attribute payload
1057  * @data: head of attribute payload
1058  *
1059  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
1060  * the attribute header and payload.
1061  */
1062 int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
1063 {
1064         if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
1065                 return -EMSGSIZE;
1066
1067         __nla_put(skb, attrtype, attrlen, data);
1068         return 0;
1069 }
1070 EXPORT_SYMBOL(nla_put);
1071
1072 /**
1073  * nla_put_64bit - Add a netlink attribute to a socket buffer and align it
1074  * @skb: socket buffer to add attribute to
1075  * @attrtype: attribute type
1076  * @attrlen: length of attribute payload
1077  * @data: head of attribute payload
1078  * @padattr: attribute type for the padding
1079  *
1080  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
1081  * the attribute header and payload.
1082  */
1083 int nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
1084                   const void *data, int padattr)
1085 {
1086         size_t len;
1087
1088         if (nla_need_padding_for_64bit(skb))
1089                 len = nla_total_size_64bit(attrlen);
1090         else
1091                 len = nla_total_size(attrlen);
1092         if (unlikely(skb_tailroom(skb) < len))
1093                 return -EMSGSIZE;
1094
1095         __nla_put_64bit(skb, attrtype, attrlen, data, padattr);
1096         return 0;
1097 }
1098 EXPORT_SYMBOL(nla_put_64bit);
1099
1100 /**
1101  * nla_put_nohdr - Add a netlink attribute without header
1102  * @skb: socket buffer to add attribute to
1103  * @attrlen: length of attribute payload
1104  * @data: head of attribute payload
1105  *
1106  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
1107  * the attribute payload.
1108  */
1109 int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
1110 {
1111         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
1112                 return -EMSGSIZE;
1113
1114         __nla_put_nohdr(skb, attrlen, data);
1115         return 0;
1116 }
1117 EXPORT_SYMBOL(nla_put_nohdr);
1118
1119 /**
1120  * nla_append - Add a netlink attribute without header or padding
1121  * @skb: socket buffer to add attribute to
1122  * @attrlen: length of attribute payload
1123  * @data: head of attribute payload
1124  *
1125  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
1126  * the attribute payload.
1127  */
1128 int nla_append(struct sk_buff *skb, int attrlen, const void *data)
1129 {
1130         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
1131                 return -EMSGSIZE;
1132
1133         skb_put_data(skb, data, attrlen);
1134         return 0;
1135 }
1136 EXPORT_SYMBOL(nla_append);
1137 #endif