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 */
  24static 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
  37static 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
  60static 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
  66static 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
  89static 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
 119void 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
 170static 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
 242void 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
 287static 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
 325static 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
 353static 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
 393static 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;
 598out_err:
 599	NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
 600				"Attribute failed policy validation");
 601	return err;
 602}
 603
 604static 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 */
 673int __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}
 680EXPORT_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 */
 693int
 694nla_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}
 709EXPORT_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 */
 727int __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}
 735EXPORT_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 */
 745struct 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}
 756EXPORT_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 */
 772ssize_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}
 799EXPORT_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 */
 808char *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}
 823EXPORT_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 */
 836int 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}
 846EXPORT_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 */
 854int 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}
 864EXPORT_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 */
 871int 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}
 887EXPORT_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 */
 902struct 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}
 914EXPORT_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 */
 930struct 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}
 937EXPORT_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 */
 949void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
 950{
 951	return skb_put_zero(skb, NLA_ALIGN(attrlen));
 952}
 953EXPORT_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 */
 967struct 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}
 974EXPORT_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 */
 990struct 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}
1004EXPORT_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 */
1016void *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}
1023EXPORT_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 */
1035void __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}
1043EXPORT_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 */
1056void __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}
1064EXPORT_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 */
1075void __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}
1082EXPORT_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 */
1094int 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}
1102EXPORT_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 */
1115int 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}
1130EXPORT_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 */
1141int 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}
1149EXPORT_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 */
1160int 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}
1168EXPORT_SYMBOL(nla_append);
1169#endif