1 // SPDX-License-Identifier: GPL-2.0
3 * NETLINK Netlink attributes
5 * Authors: Thomas Graf <tgraf@suug.ch>
6 * Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
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>
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.
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),
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),
47 static int validate_nla_bitfield32(const struct nlattr *nla,
48 const u32 *valid_flags_mask)
50 const struct nla_bitfield32 *bf = nla_data(nla);
52 if (!valid_flags_mask)
55 /*disallow invalid bit selector */
56 if (bf->selector & ~*valid_flags_mask)
59 /*disallow invalid bit values */
60 if (bf->value & ~*valid_flags_mask)
63 /*disallow valid bit values that are not selected*/
64 if (bf->value & ~bf->selector)
70 static int nla_validate_array(const struct nlattr *head, int len, int maxtype,
71 const struct nla_policy *policy,
72 struct netlink_ext_ack *extack)
74 const struct nlattr *entry;
77 nla_for_each_attr(entry, head, len, rem) {
80 if (nla_len(entry) == 0)
83 if (nla_len(entry) < NLA_HDRLEN) {
84 NL_SET_ERR_MSG_ATTR(extack, entry,
85 "Array element too short");
89 ret = nla_validate(nla_data(entry), nla_len(entry),
90 maxtype, policy, extack);
98 static int nla_validate_int_range(const struct nla_policy *pt,
99 const struct nlattr *nla,
100 struct netlink_ext_ack *extack)
102 bool validate_min, validate_max;
105 validate_min = pt->validation_type == NLA_VALIDATE_RANGE ||
106 pt->validation_type == NLA_VALIDATE_MIN;
107 validate_max = pt->validation_type == NLA_VALIDATE_RANGE ||
108 pt->validation_type == NLA_VALIDATE_MAX;
112 value = nla_get_u8(nla);
115 value = nla_get_u16(nla);
118 value = nla_get_u32(nla);
121 value = nla_get_s8(nla);
124 value = nla_get_s16(nla);
127 value = nla_get_s32(nla);
130 value = nla_get_s64(nla);
133 /* treat this one specially, since it may not fit into s64 */
134 if ((validate_min && nla_get_u64(nla) < pt->min) ||
135 (validate_max && nla_get_u64(nla) > pt->max)) {
136 NL_SET_ERR_MSG_ATTR(extack, nla,
137 "integer out of range");
146 if ((validate_min && value < pt->min) ||
147 (validate_max && value > pt->max)) {
148 NL_SET_ERR_MSG_ATTR(extack, nla,
149 "integer out of range");
156 static int validate_nla(const struct nlattr *nla, int maxtype,
157 const struct nla_policy *policy,
158 struct netlink_ext_ack *extack)
160 const struct nla_policy *pt;
161 int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
164 if (type <= 0 || type > maxtype)
169 BUG_ON(pt->type > NLA_TYPE_MAX);
171 if ((nla_attr_len[pt->type] && attrlen != nla_attr_len[pt->type]) ||
172 (pt->type == NLA_EXACT_LEN_WARN && attrlen != pt->len)) {
173 pr_warn_ratelimited("netlink: '%s': attribute type %d has an invalid length.\n",
174 current->comm, type);
179 if (attrlen != pt->len)
184 if (extack && pt->validation_data) {
185 NL_SET_BAD_ATTR(extack, nla);
186 extack->_msg = pt->validation_data;
198 if (attrlen != sizeof(struct nla_bitfield32))
201 err = validate_nla_bitfield32(nla, pt->validation_data);
208 minlen = min_t(int, attrlen, pt->len + 1);
212 if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL) {
223 char *buf = nla_data(nla);
225 if (buf[attrlen - 1] == '\0')
228 if (attrlen > pt->len)
234 if (pt->len && attrlen > pt->len)
239 /* a nested attributes is allowed to be empty; if its not,
240 * it must have a size of at least NLA_HDRLEN.
244 if (attrlen < NLA_HDRLEN)
246 if (pt->validation_data) {
247 err = nla_validate(nla_data(nla), nla_len(nla), pt->len,
248 pt->validation_data, extack);
251 * return directly to preserve the inner
252 * error message/attribute pointer
258 case NLA_NESTED_ARRAY:
259 /* a nested array attribute is allowed to be empty; if its not,
260 * it must have a size of at least NLA_HDRLEN.
264 if (attrlen < NLA_HDRLEN)
266 if (pt->validation_data) {
269 err = nla_validate_array(nla_data(nla), nla_len(nla),
270 pt->len, pt->validation_data,
274 * return directly to preserve the inner
275 * error message/attribute pointer
284 else if (pt->type != NLA_UNSPEC)
285 minlen = nla_attr_minlen[pt->type];
287 if (attrlen < minlen)
291 /* further validation */
292 switch (pt->validation_type) {
293 case NLA_VALIDATE_NONE:
296 case NLA_VALIDATE_RANGE:
297 case NLA_VALIDATE_MIN:
298 case NLA_VALIDATE_MAX:
299 err = nla_validate_int_range(pt, nla, extack);
303 case NLA_VALIDATE_FUNCTION:
305 err = pt->validate(nla, extack);
314 NL_SET_ERR_MSG_ATTR(extack, nla, "Attribute failed policy validation");
319 * nla_validate - Validate a stream of attributes
320 * @head: head of attribute stream
321 * @len: length of attribute stream
322 * @maxtype: maximum attribute type to be expected
323 * @policy: validation policy
324 * @extack: extended ACK report struct
326 * Validates all attributes in the specified attribute stream against the
327 * specified policy. Attributes with a type exceeding maxtype will be
328 * ignored. See documenation of struct nla_policy for more details.
330 * Returns 0 on success or a negative error code.
332 int nla_validate(const struct nlattr *head, int len, int maxtype,
333 const struct nla_policy *policy,
334 struct netlink_ext_ack *extack)
336 const struct nlattr *nla;
339 nla_for_each_attr(nla, head, len, rem) {
340 int err = validate_nla(nla, maxtype, policy, extack);
348 EXPORT_SYMBOL(nla_validate);
351 * nla_policy_len - Determin the max. length of a policy
352 * @policy: policy to use
353 * @n: number of policies
355 * Determines the max. length of the policy. It is currently used
356 * to allocated Netlink buffers roughly the size of the actual
359 * Returns 0 on success or a negative error code.
362 nla_policy_len(const struct nla_policy *p, int n)
366 for (i = 0; i < n; i++, p++) {
368 len += nla_total_size(p->len);
369 else if (nla_attr_len[p->type])
370 len += nla_total_size(nla_attr_len[p->type]);
371 else if (nla_attr_minlen[p->type])
372 len += nla_total_size(nla_attr_minlen[p->type]);
377 EXPORT_SYMBOL(nla_policy_len);
380 * nla_parse - Parse a stream of attributes into a tb buffer
381 * @tb: destination array with maxtype+1 elements
382 * @maxtype: maximum attribute type to be expected
383 * @head: head of attribute stream
384 * @len: length of attribute stream
385 * @policy: validation policy
387 * Parses a stream of attributes and stores a pointer to each attribute in
388 * the tb array accessible via the attribute type. Attributes with a type
389 * exceeding maxtype will be silently ignored for backwards compatibility
390 * reasons. policy may be set to NULL if no validation is required.
392 * Returns 0 on success or a negative error code.
394 int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head,
395 int len, const struct nla_policy *policy,
396 struct netlink_ext_ack *extack)
398 const struct nlattr *nla;
401 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
403 nla_for_each_attr(nla, head, len, rem) {
404 u16 type = nla_type(nla);
406 if (type > 0 && type <= maxtype) {
408 int err = validate_nla(nla, maxtype, policy,
415 tb[type] = (struct nlattr *)nla;
419 if (unlikely(rem > 0))
420 pr_warn_ratelimited("netlink: %d bytes leftover after parsing attributes in process `%s'.\n",
425 EXPORT_SYMBOL(nla_parse);
428 * nla_find - Find a specific attribute in a stream of attributes
429 * @head: head of attribute stream
430 * @len: length of attribute stream
431 * @attrtype: type of attribute to look for
433 * Returns the first attribute in the stream matching the specified type.
435 struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype)
437 const struct nlattr *nla;
440 nla_for_each_attr(nla, head, len, rem)
441 if (nla_type(nla) == attrtype)
442 return (struct nlattr *)nla;
446 EXPORT_SYMBOL(nla_find);
449 * nla_strlcpy - Copy string attribute payload into a sized buffer
450 * @dst: where to copy the string to
451 * @nla: attribute to copy the string from
452 * @dstsize: size of destination buffer
454 * Copies at most dstsize - 1 bytes into the destination buffer.
455 * The result is always a valid NUL-terminated string. Unlike
456 * strlcpy the destination buffer is always padded out.
458 * Returns the length of the source buffer.
460 size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
462 size_t srclen = nla_len(nla);
463 char *src = nla_data(nla);
465 if (srclen > 0 && src[srclen - 1] == '\0')
469 size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
471 memset(dst, 0, dstsize);
472 memcpy(dst, src, len);
477 EXPORT_SYMBOL(nla_strlcpy);
480 * nla_strdup - Copy string attribute payload into a newly allocated buffer
481 * @nla: attribute to copy the string from
482 * @flags: the type of memory to allocate (see kmalloc).
484 * Returns a pointer to the allocated buffer or NULL on error.
486 char *nla_strdup(const struct nlattr *nla, gfp_t flags)
488 size_t srclen = nla_len(nla);
489 char *src = nla_data(nla), *dst;
491 if (srclen > 0 && src[srclen - 1] == '\0')
494 dst = kmalloc(srclen + 1, flags);
496 memcpy(dst, src, srclen);
501 EXPORT_SYMBOL(nla_strdup);
504 * nla_memcpy - Copy a netlink attribute into another memory area
505 * @dest: where to copy to memcpy
506 * @src: netlink attribute to copy from
507 * @count: size of the destination area
509 * Note: The number of bytes copied is limited by the length of
510 * attribute's payload. memcpy
512 * Returns the number of bytes copied.
514 int nla_memcpy(void *dest, const struct nlattr *src, int count)
516 int minlen = min_t(int, count, nla_len(src));
518 memcpy(dest, nla_data(src), minlen);
520 memset(dest + minlen, 0, count - minlen);
524 EXPORT_SYMBOL(nla_memcpy);
527 * nla_memcmp - Compare an attribute with sized memory area
528 * @nla: netlink attribute
530 * @size: size of memory area
532 int nla_memcmp(const struct nlattr *nla, const void *data,
535 int d = nla_len(nla) - size;
538 d = memcmp(nla_data(nla), data, size);
542 EXPORT_SYMBOL(nla_memcmp);
545 * nla_strcmp - Compare a string attribute against a string
546 * @nla: netlink string attribute
547 * @str: another string
549 int nla_strcmp(const struct nlattr *nla, const char *str)
551 int len = strlen(str);
552 char *buf = nla_data(nla);
553 int attrlen = nla_len(nla);
556 if (attrlen > 0 && buf[attrlen - 1] == '\0')
561 d = memcmp(nla_data(nla), str, len);
565 EXPORT_SYMBOL(nla_strcmp);
569 * __nla_reserve - reserve room for attribute on the skb
570 * @skb: socket buffer to reserve room on
571 * @attrtype: attribute type
572 * @attrlen: length of attribute payload
574 * Adds a netlink attribute header to a socket buffer and reserves
575 * room for the payload but does not copy it.
577 * The caller is responsible to ensure that the skb provides enough
578 * tailroom for the attribute header and payload.
580 struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
584 nla = skb_put(skb, nla_total_size(attrlen));
585 nla->nla_type = attrtype;
586 nla->nla_len = nla_attr_size(attrlen);
588 memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
592 EXPORT_SYMBOL(__nla_reserve);
595 * __nla_reserve_64bit - reserve room for attribute on the skb and align it
596 * @skb: socket buffer to reserve room on
597 * @attrtype: attribute type
598 * @attrlen: length of attribute payload
599 * @padattr: attribute type for the padding
601 * Adds a netlink attribute header to a socket buffer and reserves
602 * room for the payload but does not copy it. It also ensure that this
603 * attribute will have a 64-bit aligned nla_data() area.
605 * The caller is responsible to ensure that the skb provides enough
606 * tailroom for the attribute header and payload.
608 struct nlattr *__nla_reserve_64bit(struct sk_buff *skb, int attrtype,
609 int attrlen, int padattr)
611 if (nla_need_padding_for_64bit(skb))
612 nla_align_64bit(skb, padattr);
614 return __nla_reserve(skb, attrtype, attrlen);
616 EXPORT_SYMBOL(__nla_reserve_64bit);
619 * __nla_reserve_nohdr - reserve room for attribute without header
620 * @skb: socket buffer to reserve room on
621 * @attrlen: length of attribute payload
623 * Reserves room for attribute payload without a header.
625 * The caller is responsible to ensure that the skb provides enough
626 * tailroom for the payload.
628 void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
630 return skb_put_zero(skb, NLA_ALIGN(attrlen));
632 EXPORT_SYMBOL(__nla_reserve_nohdr);
635 * nla_reserve - reserve room for attribute on the skb
636 * @skb: socket buffer to reserve room on
637 * @attrtype: attribute type
638 * @attrlen: length of attribute payload
640 * Adds a netlink attribute header to a socket buffer and reserves
641 * room for the payload but does not copy it.
643 * Returns NULL if the tailroom of the skb is insufficient to store
644 * the attribute header and payload.
646 struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
648 if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
651 return __nla_reserve(skb, attrtype, attrlen);
653 EXPORT_SYMBOL(nla_reserve);
656 * nla_reserve_64bit - reserve room for attribute on the skb and align it
657 * @skb: socket buffer to reserve room on
658 * @attrtype: attribute type
659 * @attrlen: length of attribute payload
660 * @padattr: attribute type for the padding
662 * Adds a netlink attribute header to a socket buffer and reserves
663 * room for the payload but does not copy it. It also ensure that this
664 * attribute will have a 64-bit aligned nla_data() area.
666 * Returns NULL if the tailroom of the skb is insufficient to store
667 * the attribute header and payload.
669 struct nlattr *nla_reserve_64bit(struct sk_buff *skb, int attrtype, int attrlen,
674 if (nla_need_padding_for_64bit(skb))
675 len = nla_total_size_64bit(attrlen);
677 len = nla_total_size(attrlen);
678 if (unlikely(skb_tailroom(skb) < len))
681 return __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
683 EXPORT_SYMBOL(nla_reserve_64bit);
686 * nla_reserve_nohdr - reserve room for attribute without header
687 * @skb: socket buffer to reserve room on
688 * @attrlen: length of attribute payload
690 * Reserves room for attribute payload without a header.
692 * Returns NULL if the tailroom of the skb is insufficient to store
693 * the attribute payload.
695 void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
697 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
700 return __nla_reserve_nohdr(skb, attrlen);
702 EXPORT_SYMBOL(nla_reserve_nohdr);
705 * __nla_put - Add a netlink attribute to a socket buffer
706 * @skb: socket buffer to add attribute to
707 * @attrtype: attribute type
708 * @attrlen: length of attribute payload
709 * @data: head of attribute payload
711 * The caller is responsible to ensure that the skb provides enough
712 * tailroom for the attribute header and payload.
714 void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
719 nla = __nla_reserve(skb, attrtype, attrlen);
720 memcpy(nla_data(nla), data, attrlen);
722 EXPORT_SYMBOL(__nla_put);
725 * __nla_put_64bit - Add a netlink attribute to a socket buffer and align it
726 * @skb: socket buffer to add attribute to
727 * @attrtype: attribute type
728 * @attrlen: length of attribute payload
729 * @data: head of attribute payload
730 * @padattr: attribute type for the padding
732 * The caller is responsible to ensure that the skb provides enough
733 * tailroom for the attribute header and payload.
735 void __nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
736 const void *data, int padattr)
740 nla = __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
741 memcpy(nla_data(nla), data, attrlen);
743 EXPORT_SYMBOL(__nla_put_64bit);
746 * __nla_put_nohdr - Add a netlink attribute without header
747 * @skb: socket buffer to add attribute to
748 * @attrlen: length of attribute payload
749 * @data: head of attribute payload
751 * The caller is responsible to ensure that the skb provides enough
752 * tailroom for the attribute payload.
754 void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
758 start = __nla_reserve_nohdr(skb, attrlen);
759 memcpy(start, data, attrlen);
761 EXPORT_SYMBOL(__nla_put_nohdr);
764 * nla_put - Add a netlink attribute to a socket buffer
765 * @skb: socket buffer to add attribute to
766 * @attrtype: attribute type
767 * @attrlen: length of attribute payload
768 * @data: head of attribute payload
770 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
771 * the attribute header and payload.
773 int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
775 if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
778 __nla_put(skb, attrtype, attrlen, data);
781 EXPORT_SYMBOL(nla_put);
784 * nla_put_64bit - Add a netlink attribute to a socket buffer and align it
785 * @skb: socket buffer to add attribute to
786 * @attrtype: attribute type
787 * @attrlen: length of attribute payload
788 * @data: head of attribute payload
789 * @padattr: attribute type for the padding
791 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
792 * the attribute header and payload.
794 int nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
795 const void *data, int padattr)
799 if (nla_need_padding_for_64bit(skb))
800 len = nla_total_size_64bit(attrlen);
802 len = nla_total_size(attrlen);
803 if (unlikely(skb_tailroom(skb) < len))
806 __nla_put_64bit(skb, attrtype, attrlen, data, padattr);
809 EXPORT_SYMBOL(nla_put_64bit);
812 * nla_put_nohdr - Add a netlink attribute without header
813 * @skb: socket buffer to add attribute to
814 * @attrlen: length of attribute payload
815 * @data: head of attribute payload
817 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
818 * the attribute payload.
820 int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
822 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
825 __nla_put_nohdr(skb, attrlen, data);
828 EXPORT_SYMBOL(nla_put_nohdr);
831 * nla_append - Add a netlink attribute without header or padding
832 * @skb: socket buffer to add attribute to
833 * @attrlen: length of attribute payload
834 * @data: head of attribute payload
836 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
837 * the attribute payload.
839 int nla_append(struct sk_buff *skb, int attrlen, const void *data)
841 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
844 skb_put_data(skb, data, attrlen);
847 EXPORT_SYMBOL(nla_append);