lib/nlattr.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * NETLINK      Netlink attributes
   4  *
   5  *              Authors:        Thomas Graf <tgraf@suug.ch>
   6  *                              Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
   7  */
   8
   9 #include <linux/export.h>
  10 #include <linux/kernel.h>
  11 #include <linux/errno.h>
  12 #include <linux/jiffies.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/string.h>
  15 #include <linux/types.h>
  16 #include <net/netlink.h>
  17
  18 /* For these data types, attribute length should be exactly the given
  19  * size. However, to maintain compatibility with broken commands, if the
  20  * attribute length does not match the expected size a warning is emitted
  21  * to the user that the command is sending invalid data and needs to be fixed.
  22  */
  23 static const u8 nla_attr_len[NLA_TYPE_MAX+1] = {
  24         [NLA_U8]        = sizeof(u8),
  25         [NLA_U16]       = sizeof(u16),
  26         [NLA_U32]       = sizeof(u32),
  27         [NLA_U64]       = sizeof(u64),
  28         [NLA_S8]        = sizeof(s8),
  29         [NLA_S16]       = sizeof(s16),
  30         [NLA_S32]       = sizeof(s32),
  31         [NLA_S64]       = sizeof(s64),
  32 };
  33
  34 static const u8 nla_attr_minlen[NLA_TYPE_MAX+1] = {
  35         [NLA_U8]        = sizeof(u8),
  36         [NLA_U16]       = sizeof(u16),
  37         [NLA_U32]       = sizeof(u32),
  38         [NLA_U64]       = sizeof(u64),
  39         [NLA_MSECS]     = sizeof(u64),
  40         [NLA_NESTED]    = NLA_HDRLEN,
  41         [NLA_S8]        = sizeof(s8),
  42         [NLA_S16]       = sizeof(s16),
  43         [NLA_S32]       = sizeof(s32),
  44         [NLA_S64]       = sizeof(s64),
  45 };
  46
  47 /*
  48  * Nested policies might refer back to the original
  49  * policy in some cases, and userspace could try to
  50  * abuse that and recurse by nesting in the right
  51  * ways. Limit recursion to avoid this problem.
  52  */
  53 #define MAX_POLICY_RECURSION_DEPTH      10
  54
  55 static int __nla_validate_parse(const struct nlattr *head, int len, int maxtype,
  56                                 const struct nla_policy *policy,
  57                                 unsigned int validate,
  58                                 struct netlink_ext_ack *extack,
  59                                 struct nlattr **tb, unsigned int depth);
  60
  61 static int validate_nla_bitfield32(const struct nlattr *nla,
  62                                    const u32 valid_flags_mask)
  63 {
  64         const struct nla_bitfield32 *bf = nla_data(nla);
  65
  66         if (!valid_flags_mask)
  67                 return -EINVAL;
  68
  69         /*disallow invalid bit selector */
  70         if (bf->selector & ~valid_flags_mask)
  71                 return -EINVAL;
  72
  73         /*disallow invalid bit values */
  74         if (bf->value & ~valid_flags_mask)
  75                 return -EINVAL;
  76
  77         /*disallow valid bit values that are not selected*/
  78         if (bf->value & ~bf->selector)
  79                 return -EINVAL;
  80
  81         return 0;
  82 }
  83
  84 static int nla_validate_array(const struct nlattr *head, int len, int maxtype,
  85                               const struct nla_policy *policy,
  86                               struct netlink_ext_ack *extack,
  87                               unsigned int validate, unsigned int depth)
  88 {
  89         const struct nlattr *entry;
  90         int rem;
  91
  92         nla_for_each_attr(entry, head, len, rem) {
  93                 int ret;
  94
  95                 if (nla_len(entry) == 0)
  96                         continue;
  97
  98                 if (nla_len(entry) < NLA_HDRLEN) {
  99                         NL_SET_ERR_MSG_ATTR(extack, entry,
 100                                             "Array element too short");
 101                         return -ERANGE;
 102                 }
 103
 104                 ret = __nla_validate_parse(nla_data(entry), nla_len(entry),
 105                                            maxtype, policy, validate, extack,
 106                                            NULL, depth + 1);
 107                 if (ret < 0)
 108                         return ret;
 109         }
 110
 111         return 0;
 112 }
 113
 114 void nla_get_range_unsigned(const struct nla_policy *pt,
 115                             struct netlink_range_validation *range)
 116 {
 117         WARN_ON_ONCE(pt->validation_type != NLA_VALIDATE_RANGE_PTR &&
 118                      (pt->min < 0 || pt->max < 0));
 119
 120         range->min = 0;
 121
 122         switch (pt->type) {
 123         case NLA_U8:
 124                 range->max = U8_MAX;
 125                 break;
 126         case NLA_U16:
 127                 range->max = U16_MAX;
 128                 break;
 129         case NLA_U32:
 130                 range->max = U32_MAX;
 131                 break;
 132         case NLA_U64:
 133         case NLA_MSECS:
 134                 range->max = U64_MAX;
 135                 break;
 136         default:
 137                 WARN_ON_ONCE(1);
 138                 return;
 139         }
 140
 141         switch (pt->validation_type) {
 142         case NLA_VALIDATE_RANGE:
 143                 range->min = pt->min;
 144                 range->max = pt->max;
 145                 break;
 146         case NLA_VALIDATE_RANGE_PTR:
 147                 *range = *pt->range;
 148                 break;
 149         case NLA_VALIDATE_MIN:
 150                 range->min = pt->min;
 151                 break;
 152         case NLA_VALIDATE_MAX:
 153                 range->max = pt->max;
 154                 break;
 155         default:
 156                 break;
 157         }
 158 }
 159
 160 static int nla_validate_int_range_unsigned(const struct nla_policy *pt,
 161                                            const struct nlattr *nla,
 162                                            struct netlink_ext_ack *extack)
 163 {
 164         struct netlink_range_validation range;
 165         u64 value;
 166
 167         switch (pt->type) {
 168         case NLA_U8:
 169                 value = nla_get_u8(nla);
 170                 break;
 171         case NLA_U16:
 172                 value = nla_get_u16(nla);
 173                 break;
 174         case NLA_U32:
 175                 value = nla_get_u32(nla);
 176                 break;
 177         case NLA_U64:
 178         case NLA_MSECS:
 179                 value = nla_get_u64(nla);
 180                 break;
 181         default:
 182                 return -EINVAL;
 183         }
 184
 185         nla_get_range_unsigned(pt, &range);
 186
 187         if (value < range.min || value > range.max) {
 188                 NL_SET_ERR_MSG_ATTR(extack, nla,
 189                                     "integer out of range");
 190                 return -ERANGE;
 191         }
 192
 193         return 0;
 194 }
 195
 196 void nla_get_range_signed(const struct nla_policy *pt,
 197                           struct netlink_range_validation_signed *range)
 198 {
 199         switch (pt->type) {
 200         case NLA_S8:
 201                 range->min = S8_MIN;
 202                 range->max = S8_MAX;
 203                 break;
 204         case NLA_S16:
 205                 range->min = S16_MIN;
 206                 range->max = S16_MAX;
 207                 break;
 208         case NLA_S32:
 209                 range->min = S32_MIN;
 210                 range->max = S32_MAX;
 211                 break;
 212         case NLA_S64:
 213                 range->min = S64_MIN;
 214                 range->max = S64_MAX;
 215                 break;
 216         default:
 217                 WARN_ON_ONCE(1);
 218                 return;
 219         }
 220
 221         switch (pt->validation_type) {
 222         case NLA_VALIDATE_RANGE:
 223                 range->min = pt->min;
 224                 range->max = pt->max;
 225                 break;
 226         case NLA_VALIDATE_RANGE_PTR:
 227                 *range = *pt->range_signed;
 228                 break;
 229         case NLA_VALIDATE_MIN:
 230                 range->min = pt->min;
 231                 break;
 232         case NLA_VALIDATE_MAX:
 233                 range->max = pt->max;
 234                 break;
 235         default:
 236                 break;
 237         }
 238 }
 239
 240 static int nla_validate_int_range_signed(const struct nla_policy *pt,
 241                                          const struct nlattr *nla,
 242                                          struct netlink_ext_ack *extack)
 243 {
 244         struct netlink_range_validation_signed range;
 245         s64 value;
 246
 247         switch (pt->type) {
 248         case NLA_S8:
 249                 value = nla_get_s8(nla);
 250                 break;
 251         case NLA_S16:
 252                 value = nla_get_s16(nla);
 253                 break;
 254         case NLA_S32:
 255                 value = nla_get_s32(nla);
 256                 break;
 257         case NLA_S64:
 258                 value = nla_get_s64(nla);
 259                 break;
 260         default:
 261                 return -EINVAL;
 262         }
 263
 264         nla_get_range_signed(pt, &range);
 265
 266         if (value < range.min || value > range.max) {
 267                 NL_SET_ERR_MSG_ATTR(extack, nla,
 268                                     "integer out of range");
 269                 return -ERANGE;
 270         }
 271
 272         return 0;
 273 }
 274
 275 static int nla_validate_int_range(const struct nla_policy *pt,
 276                                   const struct nlattr *nla,
 277                                   struct netlink_ext_ack *extack)
 278 {
 279         switch (pt->type) {
 280         case NLA_U8:
 281         case NLA_U16:
 282         case NLA_U32:
 283         case NLA_U64:
 284         case NLA_MSECS:
 285                 return nla_validate_int_range_unsigned(pt, nla, extack);
 286         case NLA_S8:
 287         case NLA_S16:
 288         case NLA_S32:
 289         case NLA_S64:
 290                 return nla_validate_int_range_signed(pt, nla, extack);
 291         default:
 292                 WARN_ON(1);
 293                 return -EINVAL;
 294         }
 295 }
 296
 297 static int validate_nla(const struct nlattr *nla, int maxtype,
 298                         const struct nla_policy *policy, unsigned int validate,
 299                         struct netlink_ext_ack *extack, unsigned int depth)
 300 {
 301         u16 strict_start_type = policy[0].strict_start_type;
 302         const struct nla_policy *pt;
 303         int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
 304         int err = -ERANGE;
 305
 306         if (strict_start_type && type >= strict_start_type)
 307                 validate |= NL_VALIDATE_STRICT;
 308
 309         if (type <= 0 || type > maxtype)
 310                 return 0;
 311
 312         pt = &policy[type];
 313
 314         BUG_ON(pt->type > NLA_TYPE_MAX);
 315
 316         if ((nla_attr_len[pt->type] && attrlen != nla_attr_len[pt->type]) ||
 317             (pt->type == NLA_EXACT_LEN &&
 318              pt->validation_type == NLA_VALIDATE_WARN_TOO_LONG &&
 319              attrlen != pt->len)) {
 320                 pr_warn_ratelimited("netlink: '%s': attribute type %d has an invalid length.\n",
 321                                     current->comm, type);
 322                 if (validate & NL_VALIDATE_STRICT_ATTRS) {
 323                         NL_SET_ERR_MSG_ATTR(extack, nla,
 324                                             "invalid attribute length");
 325                         return -EINVAL;
 326                 }
 327         }
 328
 329         if (validate & NL_VALIDATE_NESTED) {
 330                 if ((pt->type == NLA_NESTED || pt->type == NLA_NESTED_ARRAY) &&
 331                     !(nla->nla_type & NLA_F_NESTED)) {
 332                         NL_SET_ERR_MSG_ATTR(extack, nla,
 333                                             "NLA_F_NESTED is missing");
 334                         return -EINVAL;
 335                 }
 336                 if (pt->type != NLA_NESTED && pt->type != NLA_NESTED_ARRAY &&
 337                     pt->type != NLA_UNSPEC && (nla->nla_type & NLA_F_NESTED)) {
 338                         NL_SET_ERR_MSG_ATTR(extack, nla,
 339                                             "NLA_F_NESTED not expected");
 340                         return -EINVAL;
 341                 }
 342         }
 343
 344         switch (pt->type) {
 345         case NLA_REJECT:
 346                 if (extack && pt->reject_message) {
 347                         NL_SET_BAD_ATTR(extack, nla);
 348                         extack->_msg = pt->reject_message;
 349                         return -EINVAL;
 350                 }
 351                 err = -EINVAL;
 352                 goto out_err;
 353
 354         case NLA_FLAG:
 355                 if (attrlen > 0)
 356                         goto out_err;
 357                 break;
 358
 359         case NLA_BITFIELD32:
 360                 if (attrlen != sizeof(struct nla_bitfield32))
 361                         goto out_err;
 362
 363                 err = validate_nla_bitfield32(nla, pt->bitfield32_valid);
 364                 if (err)
 365                         goto out_err;
 366                 break;
 367
 368         case NLA_NUL_STRING:
 369                 if (pt->len)
 370                         minlen = min_t(int, attrlen, pt->len + 1);
 371                 else
 372                         minlen = attrlen;
 373
 374                 if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL) {
 375                         err = -EINVAL;
 376                         goto out_err;
 377                 }
 378                 /* fall through */
 379
 380         case NLA_STRING:
 381                 if (attrlen < 1)
 382                         goto out_err;
 383
 384                 if (pt->len) {
 385                         char *buf = nla_data(nla);
 386
 387                         if (buf[attrlen - 1] == '\0')
 388                                 attrlen--;
 389
 390                         if (attrlen > pt->len)
 391                                 goto out_err;
 392                 }
 393                 break;
 394
 395         case NLA_BINARY:
 396                 if (pt->len && attrlen > pt->len)
 397                         goto out_err;
 398                 break;
 399
 400         case NLA_NESTED:
 401                 /* a nested attributes is allowed to be empty; if its not,
 402                  * it must have a size of at least NLA_HDRLEN.
 403                  */
 404                 if (attrlen == 0)
 405                         break;
 406                 if (attrlen < NLA_HDRLEN)
 407                         goto out_err;
 408                 if (pt->nested_policy) {
 409                         err = __nla_validate_parse(nla_data(nla), nla_len(nla),
 410                                                    pt->len, pt->nested_policy,
 411                                                    validate, extack, NULL,
 412                                                    depth + 1);
 413                         if (err < 0) {
 414                                 /*
 415                                  * return directly to preserve the inner
 416                                  * error message/attribute pointer
 417                                  */
 418                                 return err;
 419                         }
 420                 }
 421                 break;
 422         case NLA_NESTED_ARRAY:
 423                 /* a nested array attribute is allowed to be empty; if its not,
 424                  * it must have a size of at least NLA_HDRLEN.
 425                  */
 426                 if (attrlen == 0)
 427                         break;
 428                 if (attrlen < NLA_HDRLEN)
 429                         goto out_err;
 430                 if (pt->nested_policy) {
 431                         int err;
 432
 433                         err = nla_validate_array(nla_data(nla), nla_len(nla),
 434                                                  pt->len, pt->nested_policy,
 435                                                  extack, validate, depth);
 436                         if (err < 0) {
 437                                 /*
 438                                  * return directly to preserve the inner
 439                                  * error message/attribute pointer
 440                                  */
 441                                 return err;
 442                         }
 443                 }
 444                 break;
 445
 446         case NLA_UNSPEC:
 447                 if (validate & NL_VALIDATE_UNSPEC) {
 448                         NL_SET_ERR_MSG_ATTR(extack, nla,
 449                                             "Unsupported attribute");
 450                         return -EINVAL;
 451                 }
 452                 /* fall through */
 453         case NLA_MIN_LEN:
 454                 if (attrlen < pt->len)
 455                         goto out_err;
 456                 break;
 457
 458         case NLA_EXACT_LEN:
 459                 if (pt->validation_type != NLA_VALIDATE_WARN_TOO_LONG) {
 460                         if (attrlen != pt->len)
 461                                 goto out_err;
 462                         break;
 463                 }
 464                 /* fall through */
 465         default:
 466                 if (pt->len)
 467                         minlen = pt->len;
 468                 else
 469                         minlen = nla_attr_minlen[pt->type];
 470
 471                 if (attrlen < minlen)
 472                         goto out_err;
 473         }
 474
 475         /* further validation */
 476         switch (pt->validation_type) {
 477         case NLA_VALIDATE_NONE:
 478                 /* nothing to do */
 479                 break;
 480         case NLA_VALIDATE_RANGE_PTR:
 481         case NLA_VALIDATE_RANGE:
 482         case NLA_VALIDATE_MIN:
 483         case NLA_VALIDATE_MAX:
 484                 err = nla_validate_int_range(pt, nla, extack);
 485                 if (err)
 486                         return err;
 487                 break;
 488         case NLA_VALIDATE_FUNCTION:
 489                 if (pt->validate) {
 490                         err = pt->validate(nla, extack);
 491                         if (err)
 492                                 return err;
 493                 }
 494                 break;
 495         }
 496
 497         return 0;
 498 out_err:
 499         NL_SET_ERR_MSG_ATTR(extack, nla, "Attribute failed policy validation");
 500         return err;
 501 }
 502
 503 static int __nla_validate_parse(const struct nlattr *head, int len, int maxtype,
 504                                 const struct nla_policy *policy,
 505                                 unsigned int validate,
 506                                 struct netlink_ext_ack *extack,
 507                                 struct nlattr **tb, unsigned int depth)
 508 {
 509         const struct nlattr *nla;
 510         int rem;
 511
 512         if (depth >= MAX_POLICY_RECURSION_DEPTH) {
 513                 NL_SET_ERR_MSG(extack,
 514                                "allowed policy recursion depth exceeded");
 515                 return -EINVAL;
 516         }
 517
 518         if (tb)
 519                 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
 520
 521         nla_for_each_attr(nla, head, len, rem) {
 522                 u16 type = nla_type(nla);
 523
 524                 if (type == 0 || type > maxtype) {
 525                         if (validate & NL_VALIDATE_MAXTYPE) {
 526                                 NL_SET_ERR_MSG_ATTR(extack, nla,
 527                                                     "Unknown attribute type");
 528                                 return -EINVAL;
 529                         }
 530                         continue;
 531                 }
 532                 if (policy) {
 533                         int err = validate_nla(nla, maxtype, policy,
 534                                                validate, extack, depth);
 535
 536                         if (err < 0)
 537                                 return err;
 538                 }
 539
 540                 if (tb)
 541                         tb[type] = (struct nlattr *)nla;
 542         }
 543
 544         if (unlikely(rem > 0)) {
 545                 pr_warn_ratelimited("netlink: %d bytes leftover after parsing attributes in process `%s'.\n",
 546                                     rem, current->comm);
 547                 NL_SET_ERR_MSG(extack, "bytes leftover after parsing attributes");
 548                 if (validate & NL_VALIDATE_TRAILING)
 549                         return -EINVAL;
 550         }
 551
 552         return 0;
 553 }
 554
 555 /**
 556  * __nla_validate - Validate a stream of attributes
 557  * @head: head of attribute stream
 558  * @len: length of attribute stream
 559  * @maxtype: maximum attribute type to be expected
 560  * @policy: validation policy
 561  * @validate: validation strictness
 562  * @extack: extended ACK report struct
 563  *
 564  * Validates all attributes in the specified attribute stream against the
 565  * specified policy. Validation depends on the validate flags passed, see
 566  * &enum netlink_validation for more details on that.
 567  * See documenation of struct nla_policy for more details.
 568  *
 569  * Returns 0 on success or a negative error code.
 570  */
 571 int __nla_validate(const struct nlattr *head, int len, int maxtype,
 572                    const struct nla_policy *policy, unsigned int validate,
 573                    struct netlink_ext_ack *extack)
 574 {
 575         return __nla_validate_parse(head, len, maxtype, policy, validate,
 576                                     extack, NULL, 0);
 577 }
 578 EXPORT_SYMBOL(__nla_validate);
 579
 580 /**
 581  * nla_policy_len - Determin the max. length of a policy
 582  * @policy: policy to use
 583  * @n: number of policies
 584  *
 585  * Determines the max. length of the policy.  It is currently used
 586  * to allocated Netlink buffers roughly the size of the actual
 587  * message.
 588  *
 589  * Returns 0 on success or a negative error code.
 590  */
 591 int
 592 nla_policy_len(const struct nla_policy *p, int n)
 593 {
 594         int i, len = 0;
 595
 596         for (i = 0; i < n; i++, p++) {
 597                 if (p->len)
 598                         len += nla_total_size(p->len);
 599                 else if (nla_attr_len[p->type])
 600                         len += nla_total_size(nla_attr_len[p->type]);
 601                 else if (nla_attr_minlen[p->type])
 602                         len += nla_total_size(nla_attr_minlen[p->type]);
 603         }
 604
 605         return len;
 606 }
 607 EXPORT_SYMBOL(nla_policy_len);
 608
 609 /**
 610  * __nla_parse - Parse a stream of attributes into a tb buffer
 611  * @tb: destination array with maxtype+1 elements
 612  * @maxtype: maximum attribute type to be expected
 613  * @head: head of attribute stream
 614  * @len: length of attribute stream
 615  * @policy: validation policy
 616  * @validate: validation strictness
 617  * @extack: extended ACK pointer
 618  *
 619  * Parses a stream of attributes and stores a pointer to each attribute in
 620  * the tb array accessible via the attribute type.
 621  * Validation is controlled by the @validate parameter.
 622  *
 623  * Returns 0 on success or a negative error code.
 624  */
 625 int __nla_parse(struct nlattr **tb, int maxtype,
 626                 const struct nlattr *head, int len,
 627                 const struct nla_policy *policy, unsigned int validate,
 628                 struct netlink_ext_ack *extack)
 629 {
 630         return __nla_validate_parse(head, len, maxtype, policy, validate,
 631                                     extack, tb, 0);
 632 }
 633 EXPORT_SYMBOL(__nla_parse);
 634
 635 /**
 636  * nla_find - Find a specific attribute in a stream of attributes
 637  * @head: head of attribute stream
 638  * @len: length of attribute stream
 639  * @attrtype: type of attribute to look for
 640  *
 641  * Returns the first attribute in the stream matching the specified type.
 642  */
 643 struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype)
 644 {
 645         const struct nlattr *nla;
 646         int rem;
 647
 648         nla_for_each_attr(nla, head, len, rem)
 649                 if (nla_type(nla) == attrtype)
 650                         return (struct nlattr *)nla;
 651
 652         return NULL;
 653 }
 654 EXPORT_SYMBOL(nla_find);
 655
 656 /**
 657  * nla_strlcpy - Copy string attribute payload into a sized buffer
 658  * @dst: where to copy the string to
 659  * @nla: attribute to copy the string from
 660  * @dstsize: size of destination buffer
 661  *
 662  * Copies at most dstsize - 1 bytes into the destination buffer.
 663  * The result is always a valid NUL-terminated string. Unlike
 664  * strlcpy the destination buffer is always padded out.
 665  *
 666  * Returns the length of the source buffer.
 667  */
 668 size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
 669 {
 670         size_t srclen = nla_len(nla);
 671         char *src = nla_data(nla);
 672
 673         if (srclen > 0 && src[srclen - 1] == '\0')
 674                 srclen--;
 675
 676         if (dstsize > 0) {
 677                 size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
 678
 679                 memset(dst, 0, dstsize);
 680                 memcpy(dst, src, len);
 681         }
 682
 683         return srclen;
 684 }
 685 EXPORT_SYMBOL(nla_strlcpy);
 686
 687 /**
 688  * nla_strdup - Copy string attribute payload into a newly allocated buffer
 689  * @nla: attribute to copy the string from
 690  * @flags: the type of memory to allocate (see kmalloc).
 691  *
 692  * Returns a pointer to the allocated buffer or NULL on error.
 693  */
 694 char *nla_strdup(const struct nlattr *nla, gfp_t flags)
 695 {
 696         size_t srclen = nla_len(nla);
 697         char *src = nla_data(nla), *dst;
 698
 699         if (srclen > 0 && src[srclen - 1] == '\0')
 700                 srclen--;
 701
 702         dst = kmalloc(srclen + 1, flags);
 703         if (dst != NULL) {
 704                 memcpy(dst, src, srclen);
 705                 dst[srclen] = '\0';
 706         }
 707         return dst;
 708 }
 709 EXPORT_SYMBOL(nla_strdup);
 710
 711 /**
 712  * nla_memcpy - Copy a netlink attribute into another memory area
 713  * @dest: where to copy to memcpy
 714  * @src: netlink attribute to copy from
 715  * @count: size of the destination area
 716  *
 717  * Note: The number of bytes copied is limited by the length of
 718  *       attribute's payload. memcpy
 719  *
 720  * Returns the number of bytes copied.
 721  */
 722 int nla_memcpy(void *dest, const struct nlattr *src, int count)
 723 {
 724         int minlen = min_t(int, count, nla_len(src));
 725
 726         memcpy(dest, nla_data(src), minlen);
 727         if (count > minlen)
 728                 memset(dest + minlen, 0, count - minlen);
 729
 730         return minlen;
 731 }
 732 EXPORT_SYMBOL(nla_memcpy);
 733
 734 /**
 735  * nla_memcmp - Compare an attribute with sized memory area
 736  * @nla: netlink attribute
 737  * @data: memory area
 738  * @size: size of memory area
 739  */
 740 int nla_memcmp(const struct nlattr *nla, const void *data,
 741                              size_t size)
 742 {
 743         int d = nla_len(nla) - size;
 744
 745         if (d == 0)
 746                 d = memcmp(nla_data(nla), data, size);
 747
 748         return d;
 749 }
 750 EXPORT_SYMBOL(nla_memcmp);
 751
 752 /**
 753  * nla_strcmp - Compare a string attribute against a string
 754  * @nla: netlink string attribute
 755  * @str: another string
 756  */
 757 int nla_strcmp(const struct nlattr *nla, const char *str)
 758 {
 759         int len = strlen(str);
 760         char *buf = nla_data(nla);
 761         int attrlen = nla_len(nla);
 762         int d;
 763
 764         if (attrlen > 0 && buf[attrlen - 1] == '\0')
 765                 attrlen--;
 766
 767         d = attrlen - len;
 768         if (d == 0)
 769                 d = memcmp(nla_data(nla), str, len);
 770
 771         return d;
 772 }
 773 EXPORT_SYMBOL(nla_strcmp);
 774
 775 #ifdef CONFIG_NET
 776 /**
 777  * __nla_reserve - reserve room for attribute on the skb
 778  * @skb: socket buffer to reserve room on
 779  * @attrtype: attribute type
 780  * @attrlen: length of attribute payload
 781  *
 782  * Adds a netlink attribute header to a socket buffer and reserves
 783  * room for the payload but does not copy it.
 784  *
 785  * The caller is responsible to ensure that the skb provides enough
 786  * tailroom for the attribute header and payload.
 787  */
 788 struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
 789 {
 790         struct nlattr *nla;
 791
 792         nla = skb_put(skb, nla_total_size(attrlen));
 793         nla->nla_type = attrtype;
 794         nla->nla_len = nla_attr_size(attrlen);
 795
 796         memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
 797
 798         return nla;
 799 }
 800 EXPORT_SYMBOL(__nla_reserve);
 801
 802 /**
 803  * __nla_reserve_64bit - reserve room for attribute on the skb and align it
 804  * @skb: socket buffer to reserve room on
 805  * @attrtype: attribute type
 806  * @attrlen: length of attribute payload
 807  * @padattr: attribute type for the padding
 808  *
 809  * Adds a netlink attribute header to a socket buffer and reserves
 810  * room for the payload but does not copy it. It also ensure that this
 811  * attribute will have a 64-bit aligned nla_data() area.
 812  *
 813  * The caller is responsible to ensure that the skb provides enough
 814  * tailroom for the attribute header and payload.
 815  */
 816 struct nlattr *__nla_reserve_64bit(struct sk_buff *skb, int attrtype,
 817                                    int attrlen, int padattr)
 818 {
 819         if (nla_need_padding_for_64bit(skb))
 820                 nla_align_64bit(skb, padattr);
 821
 822         return __nla_reserve(skb, attrtype, attrlen);
 823 }
 824 EXPORT_SYMBOL(__nla_reserve_64bit);
 825
 826 /**
 827  * __nla_reserve_nohdr - reserve room for attribute without header
 828  * @skb: socket buffer to reserve room on
 829  * @attrlen: length of attribute payload
 830  *
 831  * Reserves room for attribute payload without a header.
 832  *
 833  * The caller is responsible to ensure that the skb provides enough
 834  * tailroom for the payload.
 835  */
 836 void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
 837 {
 838         return skb_put_zero(skb, NLA_ALIGN(attrlen));
 839 }
 840 EXPORT_SYMBOL(__nla_reserve_nohdr);
 841
 842 /**
 843  * nla_reserve - reserve room for attribute on the skb
 844  * @skb: socket buffer to reserve room on
 845  * @attrtype: attribute type
 846  * @attrlen: length of attribute payload
 847  *
 848  * Adds a netlink attribute header to a socket buffer and reserves
 849  * room for the payload but does not copy it.
 850  *
 851  * Returns NULL if the tailroom of the skb is insufficient to store
 852  * the attribute header and payload.
 853  */
 854 struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
 855 {
 856         if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
 857                 return NULL;
 858
 859         return __nla_reserve(skb, attrtype, attrlen);
 860 }
 861 EXPORT_SYMBOL(nla_reserve);
 862
 863 /**
 864  * nla_reserve_64bit - reserve room for attribute on the skb and align it
 865  * @skb: socket buffer to reserve room on
 866  * @attrtype: attribute type
 867  * @attrlen: length of attribute payload
 868  * @padattr: attribute type for the padding
 869  *
 870  * Adds a netlink attribute header to a socket buffer and reserves
 871  * room for the payload but does not copy it. It also ensure that this
 872  * attribute will have a 64-bit aligned nla_data() area.
 873  *
 874  * Returns NULL if the tailroom of the skb is insufficient to store
 875  * the attribute header and payload.
 876  */
 877 struct nlattr *nla_reserve_64bit(struct sk_buff *skb, int attrtype, int attrlen,
 878                                  int padattr)
 879 {
 880         size_t len;
 881
 882         if (nla_need_padding_for_64bit(skb))
 883                 len = nla_total_size_64bit(attrlen);
 884         else
 885                 len = nla_total_size(attrlen);
 886         if (unlikely(skb_tailroom(skb) < len))
 887                 return NULL;
 888
 889         return __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
 890 }
 891 EXPORT_SYMBOL(nla_reserve_64bit);
 892
 893 /**
 894  * nla_reserve_nohdr - reserve room for attribute without header
 895  * @skb: socket buffer to reserve room on
 896  * @attrlen: length of attribute payload
 897  *
 898  * Reserves room for attribute payload without a header.
 899  *
 900  * Returns NULL if the tailroom of the skb is insufficient to store
 901  * the attribute payload.
 902  */
 903 void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
 904 {
 905         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
 906                 return NULL;
 907
 908         return __nla_reserve_nohdr(skb, attrlen);
 909 }
 910 EXPORT_SYMBOL(nla_reserve_nohdr);
 911
 912 /**
 913  * __nla_put - Add a netlink attribute to a socket buffer
 914  * @skb: socket buffer to add attribute to
 915  * @attrtype: attribute type
 916  * @attrlen: length of attribute payload
 917  * @data: head of attribute payload
 918  *
 919  * The caller is responsible to ensure that the skb provides enough
 920  * tailroom for the attribute header and payload.
 921  */
 922 void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
 923                              const void *data)
 924 {
 925         struct nlattr *nla;
 926
 927         nla = __nla_reserve(skb, attrtype, attrlen);
 928         memcpy(nla_data(nla), data, attrlen);
 929 }
 930 EXPORT_SYMBOL(__nla_put);
 931
 932 /**
 933  * __nla_put_64bit - Add a netlink attribute to a socket buffer and align it
 934  * @skb: socket buffer to add attribute to
 935  * @attrtype: attribute type
 936  * @attrlen: length of attribute payload
 937  * @data: head of attribute payload
 938  * @padattr: attribute type for the padding
 939  *
 940  * The caller is responsible to ensure that the skb provides enough
 941  * tailroom for the attribute header and payload.
 942  */
 943 void __nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
 944                      const void *data, int padattr)
 945 {
 946         struct nlattr *nla;
 947
 948         nla = __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
 949         memcpy(nla_data(nla), data, attrlen);
 950 }
 951 EXPORT_SYMBOL(__nla_put_64bit);
 952
 953 /**
 954  * __nla_put_nohdr - Add a netlink attribute without header
 955  * @skb: socket buffer to add attribute to
 956  * @attrlen: length of attribute payload
 957  * @data: head of attribute payload
 958  *
 959  * The caller is responsible to ensure that the skb provides enough
 960  * tailroom for the attribute payload.
 961  */
 962 void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
 963 {
 964         void *start;
 965
 966         start = __nla_reserve_nohdr(skb, attrlen);
 967         memcpy(start, data, attrlen);
 968 }
 969 EXPORT_SYMBOL(__nla_put_nohdr);
 970
 971 /**
 972  * nla_put - Add a netlink attribute to a socket buffer
 973  * @skb: socket buffer to add attribute to
 974  * @attrtype: attribute type
 975  * @attrlen: length of attribute payload
 976  * @data: head of attribute payload
 977  *
 978  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
 979  * the attribute header and payload.
 980  */
 981 int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
 982 {
 983         if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
 984                 return -EMSGSIZE;
 985
 986         __nla_put(skb, attrtype, attrlen, data);
 987         return 0;
 988 }
 989 EXPORT_SYMBOL(nla_put);
 990
 991 /**
 992  * nla_put_64bit - Add a netlink attribute to a socket buffer and align it
 993  * @skb: socket buffer to add attribute to
 994  * @attrtype: attribute type
 995  * @attrlen: length of attribute payload
 996  * @data: head of attribute payload
 997  * @padattr: attribute type for the padding
 998  *
 999  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
1000  * the attribute header and payload.
1001  */
1002 int nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
1003                   const void *data, int padattr)
1004 {
1005         size_t len;
1006
1007         if (nla_need_padding_for_64bit(skb))
1008                 len = nla_total_size_64bit(attrlen);
1009         else
1010                 len = nla_total_size(attrlen);
1011         if (unlikely(skb_tailroom(skb) < len))
1012                 return -EMSGSIZE;
1013
1014         __nla_put_64bit(skb, attrtype, attrlen, data, padattr);
1015         return 0;
1016 }
1017 EXPORT_SYMBOL(nla_put_64bit);
1018
1019 /**
1020  * nla_put_nohdr - Add a netlink attribute without header
1021  * @skb: socket buffer to add attribute to
1022  * @attrlen: length of attribute payload
1023  * @data: head of attribute payload
1024  *
1025  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
1026  * the attribute payload.
1027  */
1028 int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
1029 {
1030         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
1031                 return -EMSGSIZE;
1032
1033         __nla_put_nohdr(skb, attrlen, data);
1034         return 0;
1035 }
1036 EXPORT_SYMBOL(nla_put_nohdr);
1037
1038 /**
1039  * nla_append - Add a netlink attribute without header or padding
1040  * @skb: socket buffer to add attribute to
1041  * @attrlen: length of attribute payload
1042  * @data: head of attribute payload
1043  *
1044  * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
1045  * the attribute payload.
1046  */
1047 int nla_append(struct sk_buff *skb, int attrlen, const void *data)
1048 {
1049         if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
1050                 return -EMSGSIZE;
1051
1052         skb_put_data(skb, data, attrlen);
1053         return 0;
1054 }
1055 EXPORT_SYMBOL(nla_append);
1056 #endif