2 * NETLINK Netlink attributes
4 * Authors: Thomas Graf <tgraf@suug.ch>
5 * Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
8 #include <linux/module.h>
9 #include <linux/kernel.h>
10 #include <linux/errno.h>
11 #include <linux/jiffies.h>
12 #include <linux/netdevice.h>
13 #include <linux/skbuff.h>
14 #include <linux/string.h>
15 #include <linux/types.h>
16 #include <net/netlink.h>
18 static const u16 nla_attr_minlen[NLA_TYPE_MAX+1] = {
19 [NLA_U8] = sizeof(u8),
20 [NLA_U16] = sizeof(u16),
21 [NLA_U32] = sizeof(u32),
22 [NLA_U64] = sizeof(u64),
23 [NLA_MSECS] = sizeof(u64),
24 [NLA_NESTED] = NLA_HDRLEN,
27 static int validate_nla(const struct nlattr *nla, int maxtype,
28 const struct nla_policy *policy)
30 const struct nla_policy *pt;
31 int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
33 if (type <= 0 || type > maxtype)
38 BUG_ON(pt->type > NLA_TYPE_MAX);
48 minlen = min_t(int, attrlen, pt->len + 1);
52 if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL)
61 char *buf = nla_data(nla);
63 if (buf[attrlen - 1] == '\0')
66 if (attrlen > pt->len)
72 if (pt->len && attrlen > pt->len)
76 case NLA_NESTED_COMPAT:
77 if (attrlen < pt->len)
79 if (attrlen < NLA_ALIGN(pt->len))
81 if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN)
83 nla = nla_data(nla) + NLA_ALIGN(pt->len);
84 if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN + nla_len(nla))
88 /* a nested attributes is allowed to be empty; if its not,
89 * it must have a size of at least NLA_HDRLEN.
96 else if (pt->type != NLA_UNSPEC)
97 minlen = nla_attr_minlen[pt->type];
107 * nla_validate - Validate a stream of attributes
108 * @head: head of attribute stream
109 * @len: length of attribute stream
110 * @maxtype: maximum attribute type to be expected
111 * @policy: validation policy
113 * Validates all attributes in the specified attribute stream against the
114 * specified policy. Attributes with a type exceeding maxtype will be
115 * ignored. See documenation of struct nla_policy for more details.
117 * Returns 0 on success or a negative error code.
119 int nla_validate(const struct nlattr *head, int len, int maxtype,
120 const struct nla_policy *policy)
122 const struct nlattr *nla;
125 nla_for_each_attr(nla, head, len, rem) {
126 err = validate_nla(nla, maxtype, policy);
137 * nla_policy_len - Determin the max. length of a policy
138 * @policy: policy to use
139 * @n: number of policies
141 * Determines the max. length of the policy. It is currently used
142 * to allocated Netlink buffers roughly the size of the actual
145 * Returns 0 on success or a negative error code.
148 nla_policy_len(const struct nla_policy *p, int n)
152 for (i = 0; i < n; i++, p++) {
154 len += nla_total_size(p->len);
155 else if (nla_attr_minlen[p->type])
156 len += nla_total_size(nla_attr_minlen[p->type]);
163 * nla_parse - Parse a stream of attributes into a tb buffer
164 * @tb: destination array with maxtype+1 elements
165 * @maxtype: maximum attribute type to be expected
166 * @head: head of attribute stream
167 * @len: length of attribute stream
168 * @policy: validation policy
170 * Parses a stream of attributes and stores a pointer to each attribute in
171 * the tb array accessible via the attribute type. Attributes with a type
172 * exceeding maxtype will be silently ignored for backwards compatibility
173 * reasons. policy may be set to NULL if no validation is required.
175 * Returns 0 on success or a negative error code.
177 int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head,
178 int len, const struct nla_policy *policy)
180 const struct nlattr *nla;
183 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
185 nla_for_each_attr(nla, head, len, rem) {
186 u16 type = nla_type(nla);
188 if (type > 0 && type <= maxtype) {
190 err = validate_nla(nla, maxtype, policy);
195 tb[type] = (struct nlattr *)nla;
199 if (unlikely(rem > 0))
200 printk(KERN_WARNING "netlink: %d bytes leftover after parsing "
201 "attributes.\n", rem);
209 * nla_find - Find a specific attribute in a stream of attributes
210 * @head: head of attribute stream
211 * @len: length of attribute stream
212 * @attrtype: type of attribute to look for
214 * Returns the first attribute in the stream matching the specified type.
216 struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype)
218 const struct nlattr *nla;
221 nla_for_each_attr(nla, head, len, rem)
222 if (nla_type(nla) == attrtype)
223 return (struct nlattr *)nla;
229 * nla_strlcpy - Copy string attribute payload into a sized buffer
230 * @dst: where to copy the string to
231 * @nla: attribute to copy the string from
232 * @dstsize: size of destination buffer
234 * Copies at most dstsize - 1 bytes into the destination buffer.
235 * The result is always a valid NUL-terminated string. Unlike
236 * strlcpy the destination buffer is always padded out.
238 * Returns the length of the source buffer.
240 size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
242 size_t srclen = nla_len(nla);
243 char *src = nla_data(nla);
245 if (srclen > 0 && src[srclen - 1] == '\0')
249 size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
251 memset(dst, 0, dstsize);
252 memcpy(dst, src, len);
259 * nla_memcpy - Copy a netlink attribute into another memory area
260 * @dest: where to copy to memcpy
261 * @src: netlink attribute to copy from
262 * @count: size of the destination area
264 * Note: The number of bytes copied is limited by the length of
265 * attribute's payload. memcpy
267 * Returns the number of bytes copied.
269 int nla_memcpy(void *dest, const struct nlattr *src, int count)
271 int minlen = min_t(int, count, nla_len(src));
273 memcpy(dest, nla_data(src), minlen);
279 * nla_memcmp - Compare an attribute with sized memory area
280 * @nla: netlink attribute
282 * @size: size of memory area
284 int nla_memcmp(const struct nlattr *nla, const void *data,
287 int d = nla_len(nla) - size;
290 d = memcmp(nla_data(nla), data, size);
296 * nla_strcmp - Compare a string attribute against a string
297 * @nla: netlink string attribute
298 * @str: another string
300 int nla_strcmp(const struct nlattr *nla, const char *str)
302 int len = strlen(str) + 1;
303 int d = nla_len(nla) - len;
306 d = memcmp(nla_data(nla), str, len);
313 * __nla_reserve - reserve room for attribute on the skb
314 * @skb: socket buffer to reserve room on
315 * @attrtype: attribute type
316 * @attrlen: length of attribute payload
318 * Adds a netlink attribute header to a socket buffer and reserves
319 * room for the payload but does not copy it.
321 * The caller is responsible to ensure that the skb provides enough
322 * tailroom for the attribute header and payload.
324 struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
328 nla = (struct nlattr *) skb_put(skb, nla_total_size(attrlen));
329 nla->nla_type = attrtype;
330 nla->nla_len = nla_attr_size(attrlen);
332 memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
336 EXPORT_SYMBOL(__nla_reserve);
339 * __nla_reserve_nohdr - reserve room for attribute without header
340 * @skb: socket buffer to reserve room on
341 * @attrlen: length of attribute payload
343 * Reserves room for attribute payload without a header.
345 * The caller is responsible to ensure that the skb provides enough
346 * tailroom for the payload.
348 void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
352 start = skb_put(skb, NLA_ALIGN(attrlen));
353 memset(start, 0, NLA_ALIGN(attrlen));
357 EXPORT_SYMBOL(__nla_reserve_nohdr);
360 * nla_reserve - reserve room for attribute on the skb
361 * @skb: socket buffer to reserve room on
362 * @attrtype: attribute type
363 * @attrlen: length of attribute payload
365 * Adds a netlink attribute header to a socket buffer and reserves
366 * room for the payload but does not copy it.
368 * Returns NULL if the tailroom of the skb is insufficient to store
369 * the attribute header and payload.
371 struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
373 if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
376 return __nla_reserve(skb, attrtype, attrlen);
378 EXPORT_SYMBOL(nla_reserve);
381 * nla_reserve_nohdr - reserve room for attribute without header
382 * @skb: socket buffer to reserve room on
383 * @attrlen: length of attribute payload
385 * Reserves room for attribute payload without a header.
387 * Returns NULL if the tailroom of the skb is insufficient to store
388 * the attribute payload.
390 void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
392 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
395 return __nla_reserve_nohdr(skb, attrlen);
397 EXPORT_SYMBOL(nla_reserve_nohdr);
400 * __nla_put - Add a netlink attribute to a socket buffer
401 * @skb: socket buffer to add attribute to
402 * @attrtype: attribute type
403 * @attrlen: length of attribute payload
404 * @data: head of attribute payload
406 * The caller is responsible to ensure that the skb provides enough
407 * tailroom for the attribute header and payload.
409 void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
414 nla = __nla_reserve(skb, attrtype, attrlen);
415 memcpy(nla_data(nla), data, attrlen);
417 EXPORT_SYMBOL(__nla_put);
420 * __nla_put_nohdr - Add a netlink attribute without header
421 * @skb: socket buffer to add attribute to
422 * @attrlen: length of attribute payload
423 * @data: head of attribute payload
425 * The caller is responsible to ensure that the skb provides enough
426 * tailroom for the attribute payload.
428 void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
432 start = __nla_reserve_nohdr(skb, attrlen);
433 memcpy(start, data, attrlen);
435 EXPORT_SYMBOL(__nla_put_nohdr);
438 * nla_put - Add a netlink attribute to a socket buffer
439 * @skb: socket buffer to add attribute to
440 * @attrtype: attribute type
441 * @attrlen: length of attribute payload
442 * @data: head of attribute payload
444 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
445 * the attribute header and payload.
447 int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
449 if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
452 __nla_put(skb, attrtype, attrlen, data);
455 EXPORT_SYMBOL(nla_put);
458 * nla_put_nohdr - Add a netlink attribute without header
459 * @skb: socket buffer to add attribute to
460 * @attrlen: length of attribute payload
461 * @data: head of attribute payload
463 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
464 * the attribute payload.
466 int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
468 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
471 __nla_put_nohdr(skb, attrlen, data);
474 EXPORT_SYMBOL(nla_put_nohdr);
477 * nla_append - Add a netlink attribute without header or padding
478 * @skb: socket buffer to add attribute to
479 * @attrlen: length of attribute payload
480 * @data: head of attribute payload
482 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
483 * the attribute payload.
485 int nla_append(struct sk_buff *skb, int attrlen, const void *data)
487 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
490 memcpy(skb_put(skb, attrlen), data, attrlen);
493 EXPORT_SYMBOL(nla_append);
496 EXPORT_SYMBOL(nla_validate);
497 EXPORT_SYMBOL(nla_policy_len);
498 EXPORT_SYMBOL(nla_parse);
499 EXPORT_SYMBOL(nla_find);
500 EXPORT_SYMBOL(nla_strlcpy);
501 EXPORT_SYMBOL(nla_memcpy);
502 EXPORT_SYMBOL(nla_memcmp);
503 EXPORT_SYMBOL(nla_strcmp);