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         [NLA_BE16]      = sizeof(__be16),
  34         [NLA_BE32]      = sizeof(__be32),
  35 };
  36
  37 static const u8 nla_attr_minlen[NLA_TYPE_MAX+1] = {
  38         [NLA_U8]        = sizeof(u8),
  39         [NLA_U16]       = sizeof(u16),
  40         [NLA_U32]       = sizeof(u32),
  41         [NLA_U64]       = sizeof(u64),
  42         [NLA_MSECS]     = sizeof(u64),
  43         [NLA_NESTED]    = NLA_HDRLEN,
  44         [NLA_S8]        = sizeof(s8),
  45         [NLA_S16]       = sizeof(s16),
  46         [NLA_S32]       = sizeof(s32),
  47         [NLA_S64]       = sizeof(s64),
  48         [NLA_BE16]      = sizeof(__be16),
  49         [NLA_BE32]      = sizeof(__be32),
  50 };
  51
  52 /*
  53  * Nested policies might refer back to the original
  54  * policy in some cases, and userspace could try to
  55  * abuse that and recurse by nesting in the right
  56  * ways. Limit recursion to avoid this problem.
  57  */
  58 #define MAX_POLICY_RECURSION_DEPTH      10
  59
  60 static int __nla_validate_parse(const struct nlattr *head, int len, int maxtype,
  61                                 const struct nla_policy *policy,
  62                                 unsigned int validate,
  63                                 struct netlink_ext_ack *extack,
  64                                 struct nlattr **tb, unsigned int depth);
  65
  66 static int validate_nla_bitfield32(const struct nlattr *nla,
  67                                    const u32 valid_flags_mask)
  68 {
  69         const struct nla_bitfield32 *bf = nla_data(nla);
  70
  71         if (!valid_flags_mask)
  72                 return -EINVAL;
  73
  74         /*disallow invalid bit selector */
  75         if (bf->selector & ~valid_flags_mask)
  76                 return -EINVAL;
  77
  78         /*disallow invalid bit values */
  79         if (bf->value & ~valid_flags_mask)
  80                 return -EINVAL;
  81
  82         /*disallow valid bit values that are not selected*/
  83         if (bf->value & ~bf->selector)
  84                 return -EINVAL;
  85
  86         return 0;
  87 }
  88
  89 static int nla_validate_array(const struct nlattr *head, int len, int maxtype,
  90                               const struct nla_policy *policy,
  91                               struct netlink_ext_ack *extack,
  92                               unsigned int validate, unsigned int depth)
  93 {
  94         const struct nlattr *entry;
  95         int rem;
  96
  97         nla_for_each_attr(entry, head, len, rem) {
  98                 int ret;
  99
 100                 if (nla_len(entry) == 0)
 101                         continue;
 102
 103                 if (nla_len(entry) < NLA_HDRLEN) {
 104                         NL_SET_ERR_MSG_ATTR_POL(extack, entry, policy,
 105                                                 "Array element too short");
 106                         return -ERANGE;
 107                 }
 108
 109                 ret = __nla_validate_parse(nla_data(entry), nla_len(entry),
 110                                            maxtype, policy, validate, extack,
 111                                            NULL, depth + 1);
 112                 if (ret < 0)
 113                         return ret;
 114         }
 115
 116         return 0;
 117 }
 118
 119 void nla_get_range_unsigned(const struct nla_policy *pt,
 120                             struct netlink_range_validation *range)
 121 {
 122         WARN_ON_ONCE(pt->validation_type != NLA_VALIDATE_RANGE_PTR &&
 123                      (pt->min < 0 || pt->max < 0));
 124
 125         range->min = 0;
 126
 127         switch (pt->type) {
 128         case NLA_U8:
 129                 range->max = U8_MAX;
 130                 break;
 131         case NLA_U16:
 132         case NLA_BE16:
 133         case NLA_BINARY:
 134                 range->max = U16_MAX;
 135                 break;
 136         case NLA_U32:
 137         case NLA_BE32:
 138                 range->max = U32_MAX;
 139                 break;
 140         case NLA_U64:
 141         case NLA_UINT:
 142         case NLA_MSECS:
 143                 range->max = U64_MAX;
 144                 break;
 145         default:
 146                 WARN_ON_ONCE(1);
 147                 return;
 148         }
 149
 150         switch (pt->validation_type) {
 151         case NLA_VALIDATE_RANGE:
 152         case NLA_VALIDATE_RANGE_WARN_TOO_LONG:
 153                 range->min = pt->min;
 154                 range->max = pt->max;
 155                 break;
 156         case NLA_VALIDATE_RANGE_PTR:
 157                 *range = *pt->range;
 158                 break;
 159         case NLA_VALIDATE_MIN:
 160                 range->min = pt->min;
 161                 break;
 162         case NLA_VALIDATE_MAX:
 163                 range->max = pt->max;
 164                 break;
 165         default:
 166                 break;
 167         }
 168 }
 169
 170 static int nla_validate_range_unsigned(const struct nla_policy *pt,
 171                                        const struct nlattr *nla,
 172                                        struct netlink_ext_ack *extack,
 173                                        unsigned int validate)
 174 {
 175         struct netlink_range_validation range;
 176         u64 value;
 177
 178         switch (pt->type) {
 179         case NLA_U8:
 180                 value = nla_get_u8(nla);
 181                 break;
 182         case NLA_U16:
 183                 value = nla_get_u16(nla);
 184                 break;
 185         case NLA_U32:
 186                 value = nla_get_u32(nla);
 187                 break;
 188         case NLA_U64:
 189                 value = nla_get_u64(nla);
 190                 break;
 191         case NLA_UINT:
 192                 value = nla_get_uint(nla);
 193                 break;
 194         case NLA_MSECS:
 195                 value = nla_get_u64(nla);
 196                 break;
 197         case NLA_BINARY:
 198                 value = nla_len(nla);
 199                 break;
 200         case NLA_BE16:
 201                 value = ntohs(nla_get_be16(nla));
 202                 break;
 203         case NLA_BE32:
 204                 value = ntohl(nla_get_be32(nla));
 205                 break;
 206         default:
 207                 return -EINVAL;
 208         }
 209
 210         nla_get_range_unsigned(pt, &range);
 211
 212         if (pt->validation_type == NLA_VALIDATE_RANGE_WARN_TOO_LONG &&
 213             pt->type == NLA_BINARY && value > range.max) {
 214                 pr_warn_ratelimited("netlink: '%s': attribute type %d has an invalid length.\n",
 215                                     current->comm, pt->type);
 216                 if (validate & NL_VALIDATE_STRICT_ATTRS) {
 217                         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 218                                                 "invalid attribute length");
 219                         return -EINVAL;
 220                 }
 221
 222                 /* this assumes min <= max (don't validate against min) */
 223                 return 0;
 224         }
 225
 226         if (value < range.min || value > range.max) {
 227                 bool binary = pt->type == NLA_BINARY;
 228
 229                 if (binary)
 230                         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 231                                                 "binary attribute size out of range");
 232                 else
 233                         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 234                                                 "integer out of range");
 235
 236                 return -ERANGE;
 237         }
 238
 239         return 0;
 240 }
 241
 242 void nla_get_range_signed(const struct nla_policy *pt,
 243                           struct netlink_range_validation_signed *range)
 244 {
 245         switch (pt->type) {
 246         case NLA_S8:
 247                 range->min = S8_MIN;
 248                 range->max = S8_MAX;
 249                 break;
 250         case NLA_S16:
 251                 range->min = S16_MIN;
 252                 range->max = S16_MAX;
 253                 break;
 254         case NLA_S32:
 255                 range->min = S32_MIN;
 256                 range->max = S32_MAX;
 257                 break;
 258         case NLA_S64:
 259         case NLA_SINT:
 260                 range->min = S64_MIN;
 261                 range->max = S64_MAX;
 262                 break;
 263         default:
 264                 WARN_ON_ONCE(1);
 265                 return;
 266         }
 267
 268         switch (pt->validation_type) {
 269         case NLA_VALIDATE_RANGE:
 270                 range->min = pt->min;
 271                 range->max = pt->max;
 272                 break;
 273         case NLA_VALIDATE_RANGE_PTR:
 274                 *range = *pt->range_signed;
 275                 break;
 276         case NLA_VALIDATE_MIN:
 277                 range->min = pt->min;
 278                 break;
 279         case NLA_VALIDATE_MAX:
 280                 range->max = pt->max;
 281                 break;
 282         default:
 283                 break;
 284         }
 285 }
 286
 287 static int nla_validate_int_range_signed(const struct nla_policy *pt,
 288                                          const struct nlattr *nla,
 289                                          struct netlink_ext_ack *extack)
 290 {
 291         struct netlink_range_validation_signed range;
 292         s64 value;
 293
 294         switch (pt->type) {
 295         case NLA_S8:
 296                 value = nla_get_s8(nla);
 297                 break;
 298         case NLA_S16:
 299                 value = nla_get_s16(nla);
 300                 break;
 301         case NLA_S32:
 302                 value = nla_get_s32(nla);
 303                 break;
 304         case NLA_S64:
 305                 value = nla_get_s64(nla);
 306                 break;
 307         case NLA_SINT:
 308                 value = nla_get_sint(nla);
 309                 break;
 310         default:
 311                 return -EINVAL;
 312         }
 313
 314         nla_get_range_signed(pt, &range);
 315
 316         if (value < range.min || value > range.max) {
 317                 NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 318                                         "integer out of range");
 319                 return -ERANGE;
 320         }
 321
 322         return 0;
 323 }
 324
 325 static int nla_validate_int_range(const struct nla_policy *pt,
 326                                   const struct nlattr *nla,
 327                                   struct netlink_ext_ack *extack,
 328                                   unsigned int validate)
 329 {
 330         switch (pt->type) {
 331         case NLA_U8:
 332         case NLA_U16:
 333         case NLA_U32:
 334         case NLA_U64:
 335         case NLA_UINT:
 336         case NLA_MSECS:
 337         case NLA_BINARY:
 338         case NLA_BE16:
 339         case NLA_BE32:
 340                 return nla_validate_range_unsigned(pt, nla, extack, validate);
 341         case NLA_S8:
 342         case NLA_S16:
 343         case NLA_S32:
 344         case NLA_S64:
 345         case NLA_SINT:
 346                 return nla_validate_int_range_signed(pt, nla, extack);
 347         default:
 348                 WARN_ON(1);
 349                 return -EINVAL;
 350         }
 351 }
 352
 353 static int nla_validate_mask(const struct nla_policy *pt,
 354                              const struct nlattr *nla,
 355                              struct netlink_ext_ack *extack)
 356 {
 357         u64 value;
 358
 359         switch (pt->type) {
 360         case NLA_U8:
 361                 value = nla_get_u8(nla);
 362                 break;
 363         case NLA_U16:
 364                 value = nla_get_u16(nla);
 365                 break;
 366         case NLA_U32:
 367                 value = nla_get_u32(nla);
 368                 break;
 369         case NLA_U64:
 370                 value = nla_get_u64(nla);
 371                 break;
 372         case NLA_UINT:
 373                 value = nla_get_uint(nla);
 374                 break;
 375         case NLA_BE16:
 376                 value = ntohs(nla_get_be16(nla));
 377                 break;
 378         case NLA_BE32:
 379                 value = ntohl(nla_get_be32(nla));
 380                 break;
 381         default:
 382                 return -EINVAL;
 383         }
 384
 385         if (value & ~(u64)pt->mask) {
 386                 NL_SET_ERR_MSG_ATTR(extack, nla, "reserved bit set");
 387                 return -EINVAL;
 388         }
 389
 390         return 0;
 391 }
 392
 393 static int validate_nla(const struct nlattr *nla, int maxtype,
 394                         const struct nla_policy *policy, unsigned int validate,
 395                         struct netlink_ext_ack *extack, unsigned int depth)
 396 {
 397         u16 strict_start_type = policy[0].strict_start_type;
 398         const struct nla_policy *pt;
 399         int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
 400         int err = -ERANGE;
 401
 402         if (strict_start_type && type >= strict_start_type)
 403                 validate |= NL_VALIDATE_STRICT;
 404
 405         if (type <= 0 || type > maxtype)
 406                 return 0;
 407
 408         type = array_index_nospec(type, maxtype + 1);
 409         pt = &policy[type];
 410
 411         BUG_ON(pt->type > NLA_TYPE_MAX);
 412
 413         if (nla_attr_len[pt->type] && attrlen != nla_attr_len[pt->type]) {
 414                 pr_warn_ratelimited("netlink: '%s': attribute type %d has an invalid length.\n",
 415                                     current->comm, type);
 416                 if (validate & NL_VALIDATE_STRICT_ATTRS) {
 417                         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 418                                                 "invalid attribute length");
 419                         return -EINVAL;
 420                 }
 421         }
 422
 423         if (validate & NL_VALIDATE_NESTED) {
 424                 if ((pt->type == NLA_NESTED || pt->type == NLA_NESTED_ARRAY) &&
 425                     !(nla->nla_type & NLA_F_NESTED)) {
 426                         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 427                                                 "NLA_F_NESTED is missing");
 428                         return -EINVAL;
 429                 }
 430                 if (pt->type != NLA_NESTED && pt->type != NLA_NESTED_ARRAY &&
 431                     pt->type != NLA_UNSPEC && (nla->nla_type & NLA_F_NESTED)) {
 432                         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 433                                                 "NLA_F_NESTED not expected");
 434                         return -EINVAL;
 435                 }
 436         }
 437
 438         switch (pt->type) {
 439         case NLA_REJECT:
 440                 if (extack && pt->reject_message) {
 441                         NL_SET_BAD_ATTR(extack, nla);
 442                         extack->_msg = pt->reject_message;
 443                         return -EINVAL;
 444                 }
 445                 err = -EINVAL;
 446                 goto out_err;
 447
 448         case NLA_FLAG:
 449                 if (attrlen > 0)
 450                         goto out_err;
 451                 break;
 452
 453         case NLA_SINT:
 454         case NLA_UINT:
 455                 if (attrlen != sizeof(u32) && attrlen != sizeof(u64)) {
 456                         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 457                                                 "invalid attribute length");
 458                         return -EINVAL;
 459                 }
 460                 break;
 461
 462         case NLA_BITFIELD32:
 463                 if (attrlen != sizeof(struct nla_bitfield32))
 464                         goto out_err;
 465
 466                 err = validate_nla_bitfield32(nla, pt->bitfield32_valid);
 467                 if (err)
 468                         goto out_err;
 469                 break;
 470
 471         case NLA_NUL_STRING:
 472                 if (pt->len)
 473                         minlen = min_t(int, attrlen, pt->len + 1);
 474                 else
 475                         minlen = attrlen;
 476
 477                 if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL) {
 478                         err = -EINVAL;
 479                         goto out_err;
 480                 }
 481                 fallthrough;
 482
 483         case NLA_STRING:
 484                 if (attrlen < 1)
 485                         goto out_err;
 486
 487                 if (pt->len) {
 488                         char *buf = nla_data(nla);
 489
 490                         if (buf[attrlen - 1] == '\0')
 491                                 attrlen--;
 492
 493                         if (attrlen > pt->len)
 494                                 goto out_err;
 495                 }
 496                 break;
 497
 498         case NLA_BINARY:
 499                 if (pt->len && attrlen > pt->len)
 500                         goto out_err;
 501                 break;
 502
 503         case NLA_NESTED:
 504                 /* a nested attributes is allowed to be empty; if its not,
 505                  * it must have a size of at least NLA_HDRLEN.
 506                  */
 507                 if (attrlen == 0)
 508                         break;
 509                 if (attrlen < NLA_HDRLEN)
 510                         goto out_err;
 511                 if (pt->nested_policy) {
 512                         err = __nla_validate_parse(nla_data(nla), nla_len(nla),
 513                                                    pt->len, pt->nested_policy,
 514                                                    validate, extack, NULL,
 515                                                    depth + 1);
 516                         if (err < 0) {
 517                                 /*
 518                                  * return directly to preserve the inner
 519                                  * error message/attribute pointer
 520                                  */
 521                                 return err;
 522                         }
 523                 }
 524                 break;
 525         case NLA_NESTED_ARRAY:
 526                 /* a nested array attribute is allowed to be empty; if its not,
 527                  * it must have a size of at least NLA_HDRLEN.
 528                  */
 529                 if (attrlen == 0)
 530                         break;
 531                 if (attrlen < NLA_HDRLEN)
 532                         goto out_err;
 533                 if (pt->nested_policy) {
 534                         int err;
 535
 536                         err = nla_validate_array(nla_data(nla), nla_len(nla),
 537                                                  pt->len, pt->nested_policy,
 538                                                  extack, validate, depth);
 539                         if (err < 0) {
 540                                 /*
 541                                  * return directly to preserve the inner
 542                                  * error message/attribute pointer
 543                                  */
 544                                 return err;
 545                         }
 546                 }
 547                 break;
 548
 549         case NLA_UNSPEC:
 550                 if (validate & NL_VALIDATE_UNSPEC) {
 551                         NL_SET_ERR_MSG_ATTR(extack, nla,
 552                                             "Unsupported attribute");
 553                         return -EINVAL;
 554                 }
 555                 if (attrlen < pt->len)
 556                         goto out_err;
 557                 break;
 558
 559         default:
 560                 if (pt->len)
 561                         minlen = pt->len;
 562                 else
 563                         minlen = nla_attr_minlen[pt->type];
 564
 565                 if (attrlen < minlen)
 566                         goto out_err;
 567         }
 568
 569         /* further validation */
 570         switch (pt->validation_type) {
 571         case NLA_VALIDATE_NONE:
 572                 /* nothing to do */
 573                 break;
 574         case NLA_VALIDATE_RANGE_PTR:
 575         case NLA_VALIDATE_RANGE:
 576         case NLA_VALIDATE_RANGE_WARN_TOO_LONG:
 577         case NLA_VALIDATE_MIN:
 578         case NLA_VALIDATE_MAX:
 579                 err = nla_validate_int_range(pt, nla, extack, validate);
 580                 if (err)
 581                         return err;
 582                 break;
 583         case NLA_VALIDATE_MASK:
 584                 err = nla_validate_mask(pt, nla, extack);
 585                 if (err)
 586                         return err;
 587                 break;
 588         case NLA_VALIDATE_FUNCTION:
 589                 if (pt->validate) {
 590                         err = pt->validate(nla, extack);
 591                         if (err)
 592                                 return err;
 593                 }
 594                 break;
 595         }
 596
 597         return 0;
 598 out_err:
 599         NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 600                                 "Attribute failed policy validation");
 601         return err;
 602 }
 603
 604 static int __nla_validate_parse(const struct nlattr *head, int len, int maxtype,
 605                                 const struct nla_policy *policy,
 606                                 unsigned int validate,
 607                                 struct netlink_ext_ack *extack,
 608                                 struct nlattr **tb, unsigned int depth)
 609 {
 610         const struct nlattr *nla;
 611         int rem;
 612
 613         if (depth >= MAX_POLICY_RECURSION_DEPTH) {
 614                 NL_SET_ERR_MSG(extack,
 615                                "allowed policy recursion depth exceeded");
 616                 return -EINVAL;
 617         }
 618
 619         if (tb)
 620                 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
 621
 622         nla_for_each_attr(nla, head, len, rem) {
 623                 u16 type = nla_type(nla);
 624
 625                 if (type == 0 || type > maxtype) {
 626                         if (validate & NL_VALIDATE_MAXTYPE) {
 627                                 NL_SET_ERR_MSG_ATTR(extack, nla,
 628                                                     "Unknown attribute type");
 629                                 return -EINVAL;
 630                         }
 631                         continue;
 632                 }
 633                 type = array_index_nospec(type, maxtype + 1);
 634                 if (policy) {
 635                         int err = validate_nla(nla, maxtype, policy,
 636                                                validate, extack, depth);
 637
 638                         if (err < 0)
 639                                 return err;
 640                 }
 641
 642                 if (tb)
 643                         tb[type] = (struct nlattr *)nla;
 644         }
 645
 646         if (unlikely(rem > 0)) {
 647                 pr_warn_ratelimited("netlink: %d bytes leftover after parsing attributes in process `%s'.\n",
 648                                     rem, current->comm);
 649                 NL_SET_ERR_MSG(extack, "bytes leftover after parsing attributes");
 650                 if (validate & NL_VALIDATE_TRAILING)
 651                         return -EINVAL;
 652         }
 653
 654         return 0;
 655 }
 656
 657 /**
 658  * __nla_validate - Validate a stream of attributes
 659  * @head: head of attribute stream
 660  * @len: length of attribute stream
 661  * @maxtype: maximum attribute type to be expected
 662  * @policy: validation policy
 663  * @validate: validation strictness
 664  * @extack: extended ACK report struct
 665  *
 666  * Validates all attributes in the specified attribute stream against the
 667  * specified policy. Validation depends on the validate flags passed, see
 668  * &enum netlink_validation for more details on that.
 669  * See documentation of struct nla_policy for more details.
 670  *
 671  * Returns 0 on success or a negative error code.
 672  */
 673 int __nla_validate(const struct nlattr *head, int len, int maxtype,
 674                    const struct nla_policy *policy, unsigned int validate,
 675                    struct netlink_ext_ack *extack)
 676 {
 677         return __nla_validate_parse(head, len, maxtype, policy, validate,
 678                                     extack, NULL, 0);
 679 }
 680 EXPORT_SYMBOL(__nla_validate);
 681
 682 /**
 683  * nla_policy_len - Determine the max. length of a policy
 684  * @p: policy to use
 685  * @n: number of policies
 686  *
 687  * Determines the max. length of the policy.  It is currently used
 688  * to allocated Netlink buffers roughly the size of the actual
 689  * message.
 690  *
 691  * Returns 0 on success or a negative error code.
 692  */
 693 int
 694 nla_policy_len(const struct nla_policy *p, int n)
 695 {
 696         int i, len = 0;
 697
 698         for (i = 0; i < n; i++, p++) {
 699                 if (p->len)
 700                         len += nla_total_size(p->len);
 701                 else if (nla_attr_len[p->type])
 702                         len += nla_total_size(nla_attr_len[p->type]);
 703                 else if (nla_attr_minlen[p->type])
 704                         len += nla_total_size(nla_attr_minlen[p->type]);
 705         }
 706
 707         return len;
 708 }
 709 EXPORT_SYMBOL(nla_policy_len);
 710
 711 /**
 712  * __nla_parse - Parse a stream of attributes into a tb buffer
 713  * @tb: destination array with maxtype+1 elements
 714  * @maxtype: maximum attribute type to be expected
 715  * @head: head of attribute stream
 716  * @len: length of attribute stream
 717  * @policy: validation policy
 718  * @validate: validation strictness
 719  * @extack: extended ACK pointer
 720  *
 721  * Parses a stream of attributes and stores a pointer to each attribute in
 722  * the tb array accessible via the attribute type.
 723  * Validation is controlled by the @validate parameter.
 724  *
 725  * Returns 0 on success or a negative error code.
 726  */
 727 int __nla_parse(struct nlattr **tb, int maxtype,
 728                 const struct nlattr *head, int len,
 729                 const struct nla_policy *policy, unsigned int validate,
 730                 struct netlink_ext_ack *extack)
 731 {
 732         return __nla_validate_parse(head, len, maxtype, policy, validate,
 733                                     extack, tb, 0);
 734 }
 735 EXPORT_SYMBOL(__nla_parse);
 736
 737 /**
 738  * nla_find - Find a specific attribute in a stream of attributes
 739  * @head: head of attribute stream
 740  * @len: length of attribute stream
 741  * @attrtype: type of attribute to look for
 742  *
 743  * Returns the first attribute in the stream matching the specified type.
 744  */
 745 struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype)
 746 {
 747         const struct nlattr *nla;
 748         int rem;
 749
 750         nla_for_each_attr(nla, head, len, rem)
 751                 if (nla_type(nla) == attrtype)
 752                         return (struct nlattr *)nla;
 753
 754         return NULL;
 755 }
 756 EXPORT_SYMBOL(nla_find);
 757
 758 /**
 759  * nla_strscpy - Copy string attribute payload into a sized buffer
 760  * @dst: Where to copy the string to.
 761  * @nla: Attribute to copy the string from.
 762  * @dstsize: Size of destination buffer.
 763  *
 764  * Copies at most dstsize - 1 bytes into the destination buffer.
 765  * Unlike strscpy() the destination buffer is always padded out.
 766  *
 767  * Return:
 768  * * srclen - Returns @nla length (not including the trailing %NUL).
 769  * * -E2BIG - If @dstsize is 0 or greater than U16_MAX or @nla length greater
 770  *            than @dstsize.
 771  */
 772 ssize_t nla_strscpy(char *dst, const struct nlattr *nla, size_t dstsize)
 773 {
 774         size_t srclen = nla_len(nla);
 775         char *src = nla_data(nla);
 776         ssize_t ret;
 777         size_t len;
 778
 779         if (dstsize == 0 || WARN_ON_ONCE(dstsize > U16_MAX))
 780                 return -E2BIG;
 781
 782         if (srclen > 0 && src[srclen - 1] == '\0')
 783                 srclen--;
 784
 785         if (srclen >= dstsize) {
 786                 len = dstsize - 1;
 787                 ret = -E2BIG;
 788         } else {
 789                 len = srclen;
 790                 ret = len;
 791         }
 792
 793         memcpy(dst, src, len);
 794         /* Zero pad end of dst. */
 795         memset(dst + len, 0, dstsize - len);
 796
 797         return ret;
 798 }
 799 EXPORT_SYMBOL(nla_strscpy);
 800
 801 /**
 802  * nla_strdup - Copy string attribute payload into a newly allocated buffer
 803  * @nla: attribute to copy the string from
 804  * @flags: the type of memory to allocate (see kmalloc).
 805  *
 806  * Returns a pointer to the allocated buffer or NULL on error.
 807  */
 808 char *nla_strdup(const struct nlattr *nla, gfp_t flags)
 809 {
 810         size_t srclen = nla_len(nla);
 811         char *src = nla_data(nla), *dst;
 812
 813         if (srclen > 0 && src[srclen - 1] == '\0')
 814                 srclen--;
 815
 816         dst = kmalloc(srclen + 1, flags);
 817         if (dst != NULL) {
 818                 memcpy(dst, src, srclen);
 819                 dst[srclen] = '\0';
 820         }
 821         return dst;
 822 }
 823 EXPORT_SYMBOL(nla_strdup);
 824
 825 /**
 826  * nla_memcpy - Copy a netlink attribute into another memory area
 827  * @dest: where to copy to memcpy
 828  * @src: netlink attribute to copy from
 829  * @count: size of the destination area
 830  *
 831  * Note: The number of bytes copied is limited by the length of
 832  *       attribute's payload. memcpy
 833  *
 834  * Returns the number of bytes copied.
 835  */
 836 int nla_memcpy(void *dest, const struct nlattr *src, int count)
 837 {
 838         int minlen = min_t(int, count, nla_len(src));
 839
 840         memcpy(dest, nla_data(src), minlen);
 841         if (count > minlen)
 842                 memset(dest + minlen, 0, count - minlen);
 843
 844         return minlen;
 845 }
 846 EXPORT_SYMBOL(nla_memcpy);
 847
 848 /**
 849  * nla_memcmp - Compare an attribute with sized memory area
 850  * @nla: netlink attribute
 851  * @data: memory area
 852  * @size: size of memory area
 853  */
 854 int nla_memcmp(const struct nlattr *nla, const void *data,
 855                              size_t size)
 856 {
 857         int d = nla_len(nla) - size;
 858
 859         if (d == 0)
 860                 d = memcmp(nla_data(nla), data, size);
 861
 862         return d;
 863 }
 864 EXPORT_SYMBOL(nla_memcmp);
 865
 866 /**
 867  * nla_strcmp - Compare a string attribute against a string
 868  * @nla: netlink string attribute
 869  * @str: another string
 870  */
 871 int nla_strcmp(const struct nlattr *nla, const char *str)
 872 {
 873         int len = strlen(str);
 874         char *buf = nla_data(nla);
 875         int attrlen = nla_len(nla);
 876         int d;
 877
 878         while (attrlen > 0 && buf[attrlen - 1] == '\0')
 879                 attrlen--;
 880
 881         d = attrlen - len;
 882         if (d == 0)
 883                 d = memcmp(nla_data(nla), str, len);
 884
 885         return d;
 886 }
 887 EXPORT_SYMBOL(nla_strcmp);
 888
 889 #ifdef CONFIG_NET
 890 /**
 891  * __nla_reserve - reserve room for attribute on the skb
 892  * @skb: socket buffer to reserve room on
 893  * @attrtype: attribute type
 894  * @attrlen: length of attribute payload
 895  *
 896  * Adds a netlink attribute header to a socket buffer and reserves
 897  * room for the payload but does not copy it.
 898  *
 899  * The caller is responsible to ensure that the skb provides enough
 900  * tailroom for the attribute header and payload.
 901  */
 902 struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
 903 {
 904         struct nlattr *nla;
 905
 906         nla = skb_put(skb, nla_total_size(attrlen));
 907         nla->nla_type = attrtype;
 908         nla->nla_len = nla_attr_size(attrlen);
 909
 910         memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
 911
 912         return nla;
 913 }
 914 EXPORT_SYMBOL(__nla_reserve);
 915
 916 /**
 917  * __nla_reserve_64bit - reserve room for attribute on the skb and align it
 918  * @skb: socket buffer to reserve room on
 919  * @attrtype: attribute type
 920  * @attrlen: length of attribute payload
 921  * @padattr: attribute type for the padding
 922  *
 923  * Adds a netlink attribute header to a socket buffer and reserves
 924  * room for the payload but does not copy it. It also ensure that this
 925  * attribute will have a 64-bit aligned nla_data() area.
 926  *
 927  * The caller is responsible to ensure that the skb provides enough
 928  * tailroom for the attribute header and payload.
 929  */
 930 struct nlattr *__nla_reserve_64bit(struct sk_buff *skb, int attrtype,
 931                                    int attrlen, int padattr)
 932 {
 933         nla_align_64bit(skb, padattr);
 934
 935         return __nla_reserve(skb, attrtype, attrlen);
 936 }
 937 EXPORT_SYMBOL(__nla_reserve_64bit);
 938
 939 /**
 940  * __nla_reserve_nohdr - reserve room for attribute without header
 941  * @skb: socket buffer to reserve room on
 942  * @attrlen: length of attribute payload
 943  *
 944  * Reserves room for attribute payload without a header.
 945  *
 946  * The caller is responsible to ensure that the skb provides enough
 947  * tailroom for the payload.
 948  */
 949 void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
 950 {
 951         return skb_put_zero(skb, NLA_ALIGN(attrlen));
 952 }
 953 EXPORT_SYMBOL(__nla_reserve_nohdr);
 954
 955 /**
 956  * nla_reserve - reserve room for attribute on the skb
 957  * @skb: socket buffer to reserve room on
 958  * @attrtype: attribute type
 959  * @attrlen: length of attribute payload
 960  *
 961  * Adds a netlink attribute header to a socket buffer and reserves
 962  * room for the payload but does not copy it.
 963  *
 964  * Returns NULL if the tailroom of the skb is insufficient to store
 965  * the attribute header and payload.
 966  */
 967 struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
 968 {
 969         if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
 970                 return NULL;
 971
 972         return __nla_reserve(skb, attrtype, attrlen);
 973 }
 974 EXPORT_SYMBOL(nla_reserve);
 975
 976 /**
 977  * nla_reserve_64bit - reserve room for attribute on the skb and align it
 978  * @skb: socket buffer to reserve room on
 979  * @attrtype: attribute type
 980  * @attrlen: length of attribute payload
 981  * @padattr: attribute type for the padding
 982  *
 983  * Adds a netlink attribute header to a socket buffer and reserves
 984  * room for the payload but does not copy it. It also ensure that this
 985  * attribute will have a 64-bit aligned nla_data() area.
 986  *
 987  * Returns NULL if the tailroom of the skb is insufficient to store
 988  * the attribute header and payload.
 989  */
 990 struct nlattr *nla_reserve_64bit(struct sk_buff *skb, int attrtype, int attrlen,
 991                                  int padattr)
 992 {
 993         size_t len;
 994
 995         if (nla_need_padding_for_64bit(skb))
 996                 len = nla_total_size_64bit(attrlen);
 997         else
 998                 len = nla_total_size(attrlen);
 999         if (unlikely(skb_tailroom(skb) < len))
1000                 return NULL;
1001
1002         return __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
1003 }
1004 EXPORT_SYMBOL(nla_reserve_64bit);
1005
1006 /**
1007  * nla_reserve_nohdr - reserve room for attribute without header
1008  * @skb: socket buffer to reserve room on
1009  * @attrlen: length of attribute payload
1010  *
1011  * Reserves room for attribute payload without a header.
1012  *
1013  * Returns NULL if the tailroom of the skb is insufficient to store
1014  * the attribute payload.
1015  */
1016 void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
1017 {
1018         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
1019                 return NULL;
1020
1021         return __nla_reserve_nohdr(skb, attrlen);
1022 }
1023 EXPORT_SYMBOL(nla_reserve_nohdr);
1024
1025 /**
1026  * __nla_put - Add a netlink attribute to a socket buffer
1027  * @skb: socket buffer to add attribute to
1028  * @attrtype: attribute type
1029  * @attrlen: length of attribute payload
1030  * @data: head of attribute payload
1031  *
1032  * The caller is responsible to ensure that the skb provides enough
1033  * tailroom for the attribute header and payload.
1034  */
1035 void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
1036                              const void *data)
1037 {
1038         struct nlattr *nla;
1039
1040         nla = __nla_reserve(skb, attrtype, attrlen);
1041         memcpy(nla_data(nla), data, attrlen);
1042 }
1043 EXPORT_SYMBOL(__nla_put);
1044
1045 /**
1046  * __nla_put_64bit - Add a netlink attribute to a socket buffer and align it
1047  * @skb: socket buffer to add attribute to
1048  * @attrtype: attribute type
1049  * @attrlen: length of attribute payload
1050  * @data: head of attribute payload
1051  * @padattr: attribute type for the padding
1052  *
1053  * The caller is responsible to ensure that the skb provides enough
1054  * tailroom for the attribute header and payload.
1055  */
1056 void __nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
1057                      const void *data, int padattr)
1058 {
1059         struct nlattr *nla;
1060
1061         nla = __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
1062         memcpy(nla_data(nla), data, attrlen);
1063 }
1064 EXPORT_SYMBOL(__nla_put_64bit);
1065
1066 /**
1067  * __nla_put_nohdr - Add a netlink attribute without header
1068  * @skb: socket buffer to add attribute to
1069  * @attrlen: length of attribute payload
1070  * @data: head of attribute payload
1071  *
1072  * The caller is responsible to ensure that the skb provides enough
1073  * tailroom for the attribute payload.
1074  */
1075 void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
1076 {
1077         void *start;
1078
1079         start = __nla_reserve_nohdr(skb, attrlen);
1080         memcpy(start, data, attrlen);
1081 }
1082 EXPORT_SYMBOL(__nla_put_nohdr);
1083
1084 /**
1085  * nla_put - Add a netlink attribute to a socket buffer
1086  * @skb: socket buffer to add attribute to
1087  * @attrtype: attribute type
1088  * @attrlen: length of attribute payload
1089  * @data: head of attribute payload
1090  *
1091  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
1092  * the attribute header and payload.
1093  */
1094 int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
1095 {
1096         if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
1097                 return -EMSGSIZE;
1098
1099         __nla_put(skb, attrtype, attrlen, data);
1100         return 0;
1101 }
1102 EXPORT_SYMBOL(nla_put);
1103
1104 /**
1105  * nla_put_64bit - Add a netlink attribute to a socket buffer and align it
1106  * @skb: socket buffer to add attribute to
1107  * @attrtype: attribute type
1108  * @attrlen: length of attribute payload
1109  * @data: head of attribute payload
1110  * @padattr: attribute type for the padding
1111  *
1112  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
1113  * the attribute header and payload.
1114  */
1115 int nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
1116                   const void *data, int padattr)
1117 {
1118         size_t len;
1119
1120         if (nla_need_padding_for_64bit(skb))
1121                 len = nla_total_size_64bit(attrlen);
1122         else
1123                 len = nla_total_size(attrlen);
1124         if (unlikely(skb_tailroom(skb) < len))
1125                 return -EMSGSIZE;
1126
1127         __nla_put_64bit(skb, attrtype, attrlen, data, padattr);
1128         return 0;
1129 }
1130 EXPORT_SYMBOL(nla_put_64bit);
1131
1132 /**
1133  * nla_put_nohdr - Add a netlink attribute without header
1134  * @skb: socket buffer to add attribute to
1135  * @attrlen: length of attribute payload
1136  * @data: head of attribute payload
1137  *
1138  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
1139  * the attribute payload.
1140  */
1141 int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
1142 {
1143         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
1144                 return -EMSGSIZE;
1145
1146         __nla_put_nohdr(skb, attrlen, data);
1147         return 0;
1148 }
1149 EXPORT_SYMBOL(nla_put_nohdr);
1150
1151 /**
1152  * nla_append - Add a netlink attribute without header or padding
1153  * @skb: socket buffer to add attribute to
1154  * @attrlen: length of attribute payload
1155  * @data: head of attribute payload
1156  *
1157  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
1158  * the attribute payload.
1159  */
1160 int nla_append(struct sk_buff *skb, int attrlen, const void *data)
1161 {
1162         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
1163                 return -EMSGSIZE;
1164
1165         skb_put_data(skb, data, attrlen);
1166         return 0;
1167 }
1168 EXPORT_SYMBOL(nla_append);
1169 #endif