1 // SPDX-License-Identifier: GPL-2.0
3 * NETLINK Netlink attributes
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 must be exactly given size */
19 static const u8 nla_attr_len[NLA_TYPE_MAX+1] = {
20 [NLA_U8] = sizeof(u8),
21 [NLA_U16] = sizeof(u16),
22 [NLA_U32] = sizeof(u32),
23 [NLA_U64] = sizeof(u64),
24 [NLA_S8] = sizeof(s8),
25 [NLA_S16] = sizeof(s16),
26 [NLA_S32] = sizeof(s32),
27 [NLA_S64] = sizeof(s64),
30 static const u8 nla_attr_minlen[NLA_TYPE_MAX+1] = {
31 [NLA_MSECS] = sizeof(u64),
32 [NLA_NESTED] = NLA_HDRLEN,
35 static int validate_nla_bitfield32(const struct nlattr *nla,
36 u32 *valid_flags_allowed)
38 const struct nla_bitfield32 *bf = nla_data(nla);
39 u32 *valid_flags_mask = valid_flags_allowed;
41 if (!valid_flags_allowed)
44 /*disallow invalid bit selector */
45 if (bf->selector & ~*valid_flags_mask)
48 /*disallow invalid bit values */
49 if (bf->value & ~*valid_flags_mask)
52 /*disallow valid bit values that are not selected*/
53 if (bf->value & ~bf->selector)
59 static int validate_nla(const struct nlattr *nla, int maxtype,
60 const struct nla_policy *policy)
62 const struct nla_policy *pt;
63 int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
65 if (type <= 0 || type > maxtype)
70 BUG_ON(pt->type > NLA_TYPE_MAX);
72 /* for data types NLA_U* and NLA_S* require exact length */
73 if (nla_attr_len[pt->type]) {
74 if (attrlen != nla_attr_len[pt->type])
86 if (attrlen != sizeof(struct nla_bitfield32))
89 return validate_nla_bitfield32(nla, pt->validation_data);
93 minlen = min_t(int, attrlen, pt->len + 1);
97 if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL)
106 char *buf = nla_data(nla);
108 if (buf[attrlen - 1] == '\0')
111 if (attrlen > pt->len)
117 if (pt->len && attrlen > pt->len)
121 case NLA_NESTED_COMPAT:
122 if (attrlen < pt->len)
124 if (attrlen < NLA_ALIGN(pt->len))
126 if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN)
128 nla = nla_data(nla) + NLA_ALIGN(pt->len);
129 if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN + nla_len(nla))
133 /* a nested attributes is allowed to be empty; if its not,
134 * it must have a size of at least NLA_HDRLEN.
141 else if (pt->type != NLA_UNSPEC)
142 minlen = nla_attr_minlen[pt->type];
144 if (attrlen < minlen)
152 * nla_validate - Validate a stream of attributes
153 * @head: head of attribute stream
154 * @len: length of attribute stream
155 * @maxtype: maximum attribute type to be expected
156 * @policy: validation policy
157 * @extack: extended ACK report struct
159 * Validates all attributes in the specified attribute stream against the
160 * specified policy. Attributes with a type exceeding maxtype will be
161 * ignored. See documenation of struct nla_policy for more details.
163 * Returns 0 on success or a negative error code.
165 int nla_validate(const struct nlattr *head, int len, int maxtype,
166 const struct nla_policy *policy,
167 struct netlink_ext_ack *extack)
169 const struct nlattr *nla;
172 nla_for_each_attr(nla, head, len, rem) {
173 int err = validate_nla(nla, maxtype, policy);
177 extack->bad_attr = nla;
184 EXPORT_SYMBOL(nla_validate);
187 * nla_policy_len - Determin the max. length of a policy
188 * @policy: policy to use
189 * @n: number of policies
191 * Determines the max. length of the policy. It is currently used
192 * to allocated Netlink buffers roughly the size of the actual
195 * Returns 0 on success or a negative error code.
198 nla_policy_len(const struct nla_policy *p, int n)
202 for (i = 0; i < n; i++, p++) {
204 len += nla_total_size(p->len);
205 else if (nla_attr_len[p->type])
206 len += nla_total_size(nla_attr_len[p->type]);
207 else if (nla_attr_minlen[p->type])
208 len += nla_total_size(nla_attr_minlen[p->type]);
213 EXPORT_SYMBOL(nla_policy_len);
216 * nla_parse - Parse a stream of attributes into a tb buffer
217 * @tb: destination array with maxtype+1 elements
218 * @maxtype: maximum attribute type to be expected
219 * @head: head of attribute stream
220 * @len: length of attribute stream
221 * @policy: validation policy
223 * Parses a stream of attributes and stores a pointer to each attribute in
224 * the tb array accessible via the attribute type. Attributes with a type
225 * exceeding maxtype will be silently ignored for backwards compatibility
226 * reasons. policy may be set to NULL if no validation is required.
228 * Returns 0 on success or a negative error code.
230 int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head,
231 int len, const struct nla_policy *policy,
232 struct netlink_ext_ack *extack)
234 const struct nlattr *nla;
237 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
239 nla_for_each_attr(nla, head, len, rem) {
240 u16 type = nla_type(nla);
242 if (type > 0 && type <= maxtype) {
244 err = validate_nla(nla, maxtype, policy);
247 extack->bad_attr = nla;
252 tb[type] = (struct nlattr *)nla;
256 if (unlikely(rem > 0))
257 pr_warn_ratelimited("netlink: %d bytes leftover after parsing attributes in process `%s'.\n",
264 EXPORT_SYMBOL(nla_parse);
267 * nla_find - Find a specific attribute in a stream of attributes
268 * @head: head of attribute stream
269 * @len: length of attribute stream
270 * @attrtype: type of attribute to look for
272 * Returns the first attribute in the stream matching the specified type.
274 struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype)
276 const struct nlattr *nla;
279 nla_for_each_attr(nla, head, len, rem)
280 if (nla_type(nla) == attrtype)
281 return (struct nlattr *)nla;
285 EXPORT_SYMBOL(nla_find);
288 * nla_strlcpy - Copy string attribute payload into a sized buffer
289 * @dst: where to copy the string to
290 * @nla: attribute to copy the string from
291 * @dstsize: size of destination buffer
293 * Copies at most dstsize - 1 bytes into the destination buffer.
294 * The result is always a valid NUL-terminated string. Unlike
295 * strlcpy the destination buffer is always padded out.
297 * Returns the length of the source buffer.
299 size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
301 size_t srclen = nla_len(nla);
302 char *src = nla_data(nla);
304 if (srclen > 0 && src[srclen - 1] == '\0')
308 size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
310 memset(dst, 0, dstsize);
311 memcpy(dst, src, len);
316 EXPORT_SYMBOL(nla_strlcpy);
319 * nla_strdup - Copy string attribute payload into a newly allocated buffer
320 * @nla: attribute to copy the string from
321 * @flags: the type of memory to allocate (see kmalloc).
323 * Returns a pointer to the allocated buffer or NULL on error.
325 char *nla_strdup(const struct nlattr *nla, gfp_t flags)
327 size_t srclen = nla_len(nla);
328 char *src = nla_data(nla), *dst;
330 if (srclen > 0 && src[srclen - 1] == '\0')
333 dst = kmalloc(srclen + 1, flags);
335 memcpy(dst, src, srclen);
340 EXPORT_SYMBOL(nla_strdup);
343 * nla_memcpy - Copy a netlink attribute into another memory area
344 * @dest: where to copy to memcpy
345 * @src: netlink attribute to copy from
346 * @count: size of the destination area
348 * Note: The number of bytes copied is limited by the length of
349 * attribute's payload. memcpy
351 * Returns the number of bytes copied.
353 int nla_memcpy(void *dest, const struct nlattr *src, int count)
355 int minlen = min_t(int, count, nla_len(src));
357 memcpy(dest, nla_data(src), minlen);
359 memset(dest + minlen, 0, count - minlen);
363 EXPORT_SYMBOL(nla_memcpy);
366 * nla_memcmp - Compare an attribute with sized memory area
367 * @nla: netlink attribute
369 * @size: size of memory area
371 int nla_memcmp(const struct nlattr *nla, const void *data,
374 int d = nla_len(nla) - size;
377 d = memcmp(nla_data(nla), data, size);
381 EXPORT_SYMBOL(nla_memcmp);
384 * nla_strcmp - Compare a string attribute against a string
385 * @nla: netlink string attribute
386 * @str: another string
388 int nla_strcmp(const struct nlattr *nla, const char *str)
390 int len = strlen(str);
391 char *buf = nla_data(nla);
392 int attrlen = nla_len(nla);
395 if (attrlen > 0 && buf[attrlen - 1] == '\0')
400 d = memcmp(nla_data(nla), str, len);
404 EXPORT_SYMBOL(nla_strcmp);
408 * __nla_reserve - reserve room for attribute on the skb
409 * @skb: socket buffer to reserve room on
410 * @attrtype: attribute type
411 * @attrlen: length of attribute payload
413 * Adds a netlink attribute header to a socket buffer and reserves
414 * room for the payload but does not copy it.
416 * The caller is responsible to ensure that the skb provides enough
417 * tailroom for the attribute header and payload.
419 struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
423 nla = skb_put(skb, nla_total_size(attrlen));
424 nla->nla_type = attrtype;
425 nla->nla_len = nla_attr_size(attrlen);
427 memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
431 EXPORT_SYMBOL(__nla_reserve);
434 * __nla_reserve_64bit - reserve room for attribute on the skb and align it
435 * @skb: socket buffer to reserve room on
436 * @attrtype: attribute type
437 * @attrlen: length of attribute payload
438 * @padattr: attribute type for the padding
440 * Adds a netlink attribute header to a socket buffer and reserves
441 * room for the payload but does not copy it. It also ensure that this
442 * attribute will have a 64-bit aligned nla_data() area.
444 * The caller is responsible to ensure that the skb provides enough
445 * tailroom for the attribute header and payload.
447 struct nlattr *__nla_reserve_64bit(struct sk_buff *skb, int attrtype,
448 int attrlen, int padattr)
450 if (nla_need_padding_for_64bit(skb))
451 nla_align_64bit(skb, padattr);
453 return __nla_reserve(skb, attrtype, attrlen);
455 EXPORT_SYMBOL(__nla_reserve_64bit);
458 * __nla_reserve_nohdr - reserve room for attribute without header
459 * @skb: socket buffer to reserve room on
460 * @attrlen: length of attribute payload
462 * Reserves room for attribute payload without a header.
464 * The caller is responsible to ensure that the skb provides enough
465 * tailroom for the payload.
467 void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
469 return skb_put_zero(skb, NLA_ALIGN(attrlen));
471 EXPORT_SYMBOL(__nla_reserve_nohdr);
474 * nla_reserve - reserve room for attribute on the skb
475 * @skb: socket buffer to reserve room on
476 * @attrtype: attribute type
477 * @attrlen: length of attribute payload
479 * Adds a netlink attribute header to a socket buffer and reserves
480 * room for the payload but does not copy it.
482 * Returns NULL if the tailroom of the skb is insufficient to store
483 * the attribute header and payload.
485 struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
487 if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
490 return __nla_reserve(skb, attrtype, attrlen);
492 EXPORT_SYMBOL(nla_reserve);
495 * nla_reserve_64bit - reserve room for attribute on the skb and align it
496 * @skb: socket buffer to reserve room on
497 * @attrtype: attribute type
498 * @attrlen: length of attribute payload
499 * @padattr: attribute type for the padding
501 * Adds a netlink attribute header to a socket buffer and reserves
502 * room for the payload but does not copy it. It also ensure that this
503 * attribute will have a 64-bit aligned nla_data() area.
505 * Returns NULL if the tailroom of the skb is insufficient to store
506 * the attribute header and payload.
508 struct nlattr *nla_reserve_64bit(struct sk_buff *skb, int attrtype, int attrlen,
513 if (nla_need_padding_for_64bit(skb))
514 len = nla_total_size_64bit(attrlen);
516 len = nla_total_size(attrlen);
517 if (unlikely(skb_tailroom(skb) < len))
520 return __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
522 EXPORT_SYMBOL(nla_reserve_64bit);
525 * nla_reserve_nohdr - reserve room for attribute without header
526 * @skb: socket buffer to reserve room on
527 * @attrlen: length of attribute payload
529 * Reserves room for attribute payload without a header.
531 * Returns NULL if the tailroom of the skb is insufficient to store
532 * the attribute payload.
534 void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
536 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
539 return __nla_reserve_nohdr(skb, attrlen);
541 EXPORT_SYMBOL(nla_reserve_nohdr);
544 * __nla_put - Add a netlink attribute to a socket buffer
545 * @skb: socket buffer to add attribute to
546 * @attrtype: attribute type
547 * @attrlen: length of attribute payload
548 * @data: head of attribute payload
550 * The caller is responsible to ensure that the skb provides enough
551 * tailroom for the attribute header and payload.
553 void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
558 nla = __nla_reserve(skb, attrtype, attrlen);
559 memcpy(nla_data(nla), data, attrlen);
561 EXPORT_SYMBOL(__nla_put);
564 * __nla_put_64bit - Add a netlink attribute to a socket buffer and align it
565 * @skb: socket buffer to add attribute to
566 * @attrtype: attribute type
567 * @attrlen: length of attribute payload
568 * @data: head of attribute payload
569 * @padattr: attribute type for the padding
571 * The caller is responsible to ensure that the skb provides enough
572 * tailroom for the attribute header and payload.
574 void __nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
575 const void *data, int padattr)
579 nla = __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
580 memcpy(nla_data(nla), data, attrlen);
582 EXPORT_SYMBOL(__nla_put_64bit);
585 * __nla_put_nohdr - Add a netlink attribute without header
586 * @skb: socket buffer to add attribute to
587 * @attrlen: length of attribute payload
588 * @data: head of attribute payload
590 * The caller is responsible to ensure that the skb provides enough
591 * tailroom for the attribute payload.
593 void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
597 start = __nla_reserve_nohdr(skb, attrlen);
598 memcpy(start, data, attrlen);
600 EXPORT_SYMBOL(__nla_put_nohdr);
603 * nla_put - Add a netlink attribute to a socket buffer
604 * @skb: socket buffer to add attribute to
605 * @attrtype: attribute type
606 * @attrlen: length of attribute payload
607 * @data: head of attribute payload
609 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
610 * the attribute header and payload.
612 int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
614 if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
617 __nla_put(skb, attrtype, attrlen, data);
620 EXPORT_SYMBOL(nla_put);
623 * nla_put_64bit - Add a netlink attribute to a socket buffer and align it
624 * @skb: socket buffer to add attribute to
625 * @attrtype: attribute type
626 * @attrlen: length of attribute payload
627 * @data: head of attribute payload
628 * @padattr: attribute type for the padding
630 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
631 * the attribute header and payload.
633 int nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
634 const void *data, int padattr)
638 if (nla_need_padding_for_64bit(skb))
639 len = nla_total_size_64bit(attrlen);
641 len = nla_total_size(attrlen);
642 if (unlikely(skb_tailroom(skb) < len))
645 __nla_put_64bit(skb, attrtype, attrlen, data, padattr);
648 EXPORT_SYMBOL(nla_put_64bit);
651 * nla_put_nohdr - Add a netlink attribute without header
652 * @skb: socket buffer to add attribute to
653 * @attrlen: length of attribute payload
654 * @data: head of attribute payload
656 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
657 * the attribute payload.
659 int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
661 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
664 __nla_put_nohdr(skb, attrlen, data);
667 EXPORT_SYMBOL(nla_put_nohdr);
670 * nla_append - Add a netlink attribute without header or padding
671 * @skb: socket buffer to add attribute to
672 * @attrlen: length of attribute payload
673 * @data: head of attribute payload
675 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
676 * the attribute payload.
678 int nla_append(struct sk_buff *skb, int attrlen, const void *data)
680 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
683 skb_put_data(skb, data, attrlen);
686 EXPORT_SYMBOL(nla_append);