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Thomas Grafbfa83a92005-11-10 02:25:51 +01001/*
2 * NETLINK Netlink attributes
3 *
4 * Authors: Thomas Graf <tgraf@suug.ch>
5 * Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
6 */
7
Thomas Grafbfa83a92005-11-10 02:25:51 +01008#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>
17
Jan Engelhardt36546542010-11-16 09:52:32 -080018static const u16 nla_attr_minlen[NLA_TYPE_MAX+1] = {
Thomas Grafbfa83a92005-11-10 02:25:51 +010019 [NLA_U8] = sizeof(u8),
20 [NLA_U16] = sizeof(u16),
21 [NLA_U32] = sizeof(u32),
22 [NLA_U64] = sizeof(u64),
Johannes Bergc30bc942011-11-03 00:07:32 +000023 [NLA_MSECS] = sizeof(u64),
Thomas Grafbfa83a92005-11-10 02:25:51 +010024 [NLA_NESTED] = NLA_HDRLEN,
25};
26
Jan Engelhardt36546542010-11-16 09:52:32 -080027static int validate_nla(const struct nlattr *nla, int maxtype,
Patrick McHardyef7c79e2007-06-05 12:38:30 -070028 const struct nla_policy *policy)
Thomas Grafbfa83a92005-11-10 02:25:51 +010029{
Patrick McHardyef7c79e2007-06-05 12:38:30 -070030 const struct nla_policy *pt;
Thomas Graf8f4c1f92007-09-12 14:44:36 +020031 int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
Thomas Grafbfa83a92005-11-10 02:25:51 +010032
Thomas Graf8f4c1f92007-09-12 14:44:36 +020033 if (type <= 0 || type > maxtype)
Thomas Grafbfa83a92005-11-10 02:25:51 +010034 return 0;
35
Thomas Graf8f4c1f92007-09-12 14:44:36 +020036 pt = &policy[type];
Thomas Grafbfa83a92005-11-10 02:25:51 +010037
38 BUG_ON(pt->type > NLA_TYPE_MAX);
39
Thomas Grafa5531a52006-08-26 20:11:47 -070040 switch (pt->type) {
41 case NLA_FLAG:
42 if (attrlen > 0)
43 return -ERANGE;
44 break;
Thomas Grafbfa83a92005-11-10 02:25:51 +010045
Thomas Grafa5531a52006-08-26 20:11:47 -070046 case NLA_NUL_STRING:
47 if (pt->len)
48 minlen = min_t(int, attrlen, pt->len + 1);
49 else
50 minlen = attrlen;
Thomas Grafbfa83a92005-11-10 02:25:51 +010051
Thomas Grafa5531a52006-08-26 20:11:47 -070052 if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL)
53 return -EINVAL;
54 /* fall through */
55
56 case NLA_STRING:
57 if (attrlen < 1)
58 return -ERANGE;
59
60 if (pt->len) {
61 char *buf = nla_data(nla);
62
63 if (buf[attrlen - 1] == '\0')
64 attrlen--;
65
66 if (attrlen > pt->len)
67 return -ERANGE;
68 }
69 break;
70
Johannes Bergd30045a2007-03-23 11:37:48 -070071 case NLA_BINARY:
72 if (pt->len && attrlen > pt->len)
73 return -ERANGE;
74 break;
75
Patrick McHardy1092cb22007-06-25 13:49:35 -070076 case NLA_NESTED_COMPAT:
77 if (attrlen < pt->len)
78 return -ERANGE;
79 if (attrlen < NLA_ALIGN(pt->len))
80 break;
81 if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN)
82 return -ERANGE;
83 nla = nla_data(nla) + NLA_ALIGN(pt->len);
84 if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN + nla_len(nla))
85 return -ERANGE;
86 break;
Patrick McHardyea5693c2008-11-28 03:05:19 -080087 case NLA_NESTED:
88 /* a nested attributes is allowed to be empty; if its not,
89 * it must have a size of at least NLA_HDRLEN.
90 */
91 if (attrlen == 0)
92 break;
Thomas Grafa5531a52006-08-26 20:11:47 -070093 default:
94 if (pt->len)
95 minlen = pt->len;
96 else if (pt->type != NLA_UNSPEC)
97 minlen = nla_attr_minlen[pt->type];
98
99 if (attrlen < minlen)
100 return -ERANGE;
101 }
Thomas Grafbfa83a92005-11-10 02:25:51 +0100102
103 return 0;
104}
105
106/**
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
112 *
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.
116 *
117 * Returns 0 on success or a negative error code.
118 */
Jan Engelhardt36546542010-11-16 09:52:32 -0800119int nla_validate(const struct nlattr *head, int len, int maxtype,
Patrick McHardyef7c79e2007-06-05 12:38:30 -0700120 const struct nla_policy *policy)
Thomas Grafbfa83a92005-11-10 02:25:51 +0100121{
Jan Engelhardt36546542010-11-16 09:52:32 -0800122 const struct nlattr *nla;
Thomas Grafbfa83a92005-11-10 02:25:51 +0100123 int rem, err;
124
125 nla_for_each_attr(nla, head, len, rem) {
126 err = validate_nla(nla, maxtype, policy);
127 if (err < 0)
128 goto errout;
129 }
130
131 err = 0;
132errout:
133 return err;
134}
135
136/**
Holger Eitzenbergere487eb92009-03-25 18:26:30 +0100137 * nla_policy_len - Determin the max. length of a policy
138 * @policy: policy to use
139 * @n: number of policies
140 *
141 * Determines the max. length of the policy. It is currently used
142 * to allocated Netlink buffers roughly the size of the actual
143 * message.
144 *
145 * Returns 0 on success or a negative error code.
146 */
147int
148nla_policy_len(const struct nla_policy *p, int n)
149{
150 int i, len = 0;
151
Lars Ellenberge3fa3af2011-02-28 12:38:25 -0800152 for (i = 0; i < n; i++, p++) {
Holger Eitzenbergere487eb92009-03-25 18:26:30 +0100153 if (p->len)
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]);
157 }
158
159 return len;
160}
161
162/**
Thomas Grafbfa83a92005-11-10 02:25:51 +0100163 * 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
Julius Volz10b595a2008-06-27 20:02:14 -0700168 * @policy: validation policy
Thomas Grafbfa83a92005-11-10 02:25:51 +0100169 *
170 * Parses a stream of attributes and stores a pointer to each attribute in
Uwe Kleine-Königb5950762010-11-01 15:38:34 -0400171 * the tb array accessible via the attribute type. Attributes with a type
Thomas Grafbfa83a92005-11-10 02:25:51 +0100172 * exceeding maxtype will be silently ignored for backwards compatibility
173 * reasons. policy may be set to NULL if no validation is required.
174 *
175 * Returns 0 on success or a negative error code.
176 */
Jan Engelhardt36546542010-11-16 09:52:32 -0800177int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head,
178 int len, const struct nla_policy *policy)
Thomas Grafbfa83a92005-11-10 02:25:51 +0100179{
Jan Engelhardt36546542010-11-16 09:52:32 -0800180 const struct nlattr *nla;
Thomas Grafbfa83a92005-11-10 02:25:51 +0100181 int rem, err;
182
183 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
184
185 nla_for_each_attr(nla, head, len, rem) {
Thomas Graf8f4c1f92007-09-12 14:44:36 +0200186 u16 type = nla_type(nla);
Thomas Grafbfa83a92005-11-10 02:25:51 +0100187
188 if (type > 0 && type <= maxtype) {
189 if (policy) {
190 err = validate_nla(nla, maxtype, policy);
191 if (err < 0)
192 goto errout;
193 }
194
Jan Engelhardt36546542010-11-16 09:52:32 -0800195 tb[type] = (struct nlattr *)nla;
Thomas Grafbfa83a92005-11-10 02:25:51 +0100196 }
197 }
198
199 if (unlikely(rem > 0))
200 printk(KERN_WARNING "netlink: %d bytes leftover after parsing "
201 "attributes.\n", rem);
202
203 err = 0;
204errout:
205 return err;
206}
207
208/**
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
213 *
214 * Returns the first attribute in the stream matching the specified type.
215 */
Jan Engelhardt36546542010-11-16 09:52:32 -0800216struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype)
Thomas Grafbfa83a92005-11-10 02:25:51 +0100217{
Jan Engelhardt36546542010-11-16 09:52:32 -0800218 const struct nlattr *nla;
Thomas Grafbfa83a92005-11-10 02:25:51 +0100219 int rem;
220
221 nla_for_each_attr(nla, head, len, rem)
Thomas Graf8f4c1f92007-09-12 14:44:36 +0200222 if (nla_type(nla) == attrtype)
Jan Engelhardt36546542010-11-16 09:52:32 -0800223 return (struct nlattr *)nla;
Thomas Grafbfa83a92005-11-10 02:25:51 +0100224
225 return NULL;
226}
227
228/**
229 * nla_strlcpy - Copy string attribute payload into a sized buffer
230 * @dst: where to copy the string to
Julius Volz10b595a2008-06-27 20:02:14 -0700231 * @nla: attribute to copy the string from
Thomas Grafbfa83a92005-11-10 02:25:51 +0100232 * @dstsize: size of destination buffer
233 *
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.
237 *
238 * Returns the length of the source buffer.
239 */
240size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
241{
242 size_t srclen = nla_len(nla);
243 char *src = nla_data(nla);
244
245 if (srclen > 0 && src[srclen - 1] == '\0')
246 srclen--;
247
248 if (dstsize > 0) {
249 size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
250
251 memset(dst, 0, dstsize);
252 memcpy(dst, src, len);
253 }
254
255 return srclen;
256}
257
258/**
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
263 *
264 * Note: The number of bytes copied is limited by the length of
265 * attribute's payload. memcpy
266 *
267 * Returns the number of bytes copied.
268 */
Patrick McHardyb057efd2008-10-28 11:59:11 -0700269int nla_memcpy(void *dest, const struct nlattr *src, int count)
Thomas Grafbfa83a92005-11-10 02:25:51 +0100270{
271 int minlen = min_t(int, count, nla_len(src));
272
273 memcpy(dest, nla_data(src), minlen);
274
275 return minlen;
276}
277
278/**
279 * nla_memcmp - Compare an attribute with sized memory area
280 * @nla: netlink attribute
281 * @data: memory area
282 * @size: size of memory area
283 */
284int nla_memcmp(const struct nlattr *nla, const void *data,
285 size_t size)
286{
287 int d = nla_len(nla) - size;
288
289 if (d == 0)
290 d = memcmp(nla_data(nla), data, size);
291
292 return d;
293}
294
295/**
296 * nla_strcmp - Compare a string attribute against a string
297 * @nla: netlink string attribute
298 * @str: another string
299 */
300int nla_strcmp(const struct nlattr *nla, const char *str)
301{
302 int len = strlen(str) + 1;
303 int d = nla_len(nla) - len;
304
305 if (d == 0)
306 d = memcmp(nla_data(nla), str, len);
307
308 return d;
309}
310
Herbert Xu90800212009-03-11 23:18:32 +0800311#ifdef CONFIG_NET
Thomas Grafbfa83a92005-11-10 02:25:51 +0100312/**
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
317 *
318 * Adds a netlink attribute header to a socket buffer and reserves
319 * room for the payload but does not copy it.
320 *
321 * The caller is responsible to ensure that the skb provides enough
322 * tailroom for the attribute header and payload.
323 */
324struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
325{
326 struct nlattr *nla;
327
328 nla = (struct nlattr *) skb_put(skb, nla_total_size(attrlen));
329 nla->nla_type = attrtype;
330 nla->nla_len = nla_attr_size(attrlen);
331
332 memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
333
334 return nla;
335}
Herbert Xu90800212009-03-11 23:18:32 +0800336EXPORT_SYMBOL(__nla_reserve);
Thomas Grafbfa83a92005-11-10 02:25:51 +0100337
338/**
Thomas Graffe4944e2006-08-04 23:03:05 -0700339 * __nla_reserve_nohdr - reserve room for attribute without header
340 * @skb: socket buffer to reserve room on
341 * @attrlen: length of attribute payload
342 *
343 * Reserves room for attribute payload without a header.
344 *
345 * The caller is responsible to ensure that the skb provides enough
346 * tailroom for the payload.
347 */
348void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
349{
350 void *start;
351
352 start = skb_put(skb, NLA_ALIGN(attrlen));
353 memset(start, 0, NLA_ALIGN(attrlen));
354
355 return start;
356}
Herbert Xu90800212009-03-11 23:18:32 +0800357EXPORT_SYMBOL(__nla_reserve_nohdr);
Thomas Graffe4944e2006-08-04 23:03:05 -0700358
359/**
Thomas Grafbfa83a92005-11-10 02:25:51 +0100360 * 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
364 *
365 * Adds a netlink attribute header to a socket buffer and reserves
366 * room for the payload but does not copy it.
367 *
368 * Returns NULL if the tailroom of the skb is insufficient to store
369 * the attribute header and payload.
370 */
371struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
372{
373 if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
374 return NULL;
375
376 return __nla_reserve(skb, attrtype, attrlen);
377}
Herbert Xu90800212009-03-11 23:18:32 +0800378EXPORT_SYMBOL(nla_reserve);
Thomas Grafbfa83a92005-11-10 02:25:51 +0100379
380/**
Julius Volz10b595a2008-06-27 20:02:14 -0700381 * nla_reserve_nohdr - reserve room for attribute without header
Thomas Graffe4944e2006-08-04 23:03:05 -0700382 * @skb: socket buffer to reserve room on
Julius Volz10b595a2008-06-27 20:02:14 -0700383 * @attrlen: length of attribute payload
Thomas Graffe4944e2006-08-04 23:03:05 -0700384 *
385 * Reserves room for attribute payload without a header.
386 *
387 * Returns NULL if the tailroom of the skb is insufficient to store
388 * the attribute payload.
389 */
390void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
391{
392 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
393 return NULL;
394
395 return __nla_reserve_nohdr(skb, attrlen);
396}
Herbert Xu90800212009-03-11 23:18:32 +0800397EXPORT_SYMBOL(nla_reserve_nohdr);
Thomas Graffe4944e2006-08-04 23:03:05 -0700398
399/**
Thomas Grafbfa83a92005-11-10 02:25:51 +0100400 * __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
405 *
406 * The caller is responsible to ensure that the skb provides enough
407 * tailroom for the attribute header and payload.
408 */
409void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
410 const void *data)
411{
412 struct nlattr *nla;
413
414 nla = __nla_reserve(skb, attrtype, attrlen);
415 memcpy(nla_data(nla), data, attrlen);
416}
Herbert Xu90800212009-03-11 23:18:32 +0800417EXPORT_SYMBOL(__nla_put);
Thomas Grafbfa83a92005-11-10 02:25:51 +0100418
Thomas Graffe4944e2006-08-04 23:03:05 -0700419/**
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
424 *
425 * The caller is responsible to ensure that the skb provides enough
426 * tailroom for the attribute payload.
427 */
428void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
429{
430 void *start;
431
432 start = __nla_reserve_nohdr(skb, attrlen);
433 memcpy(start, data, attrlen);
434}
Herbert Xu90800212009-03-11 23:18:32 +0800435EXPORT_SYMBOL(__nla_put_nohdr);
Thomas Grafbfa83a92005-11-10 02:25:51 +0100436
437/**
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
443 *
Thomas Grafbc3ed282008-06-03 16:36:54 -0700444 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
Thomas Grafbfa83a92005-11-10 02:25:51 +0100445 * the attribute header and payload.
446 */
447int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
448{
449 if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
Thomas Grafbc3ed282008-06-03 16:36:54 -0700450 return -EMSGSIZE;
Thomas Grafbfa83a92005-11-10 02:25:51 +0100451
452 __nla_put(skb, attrtype, attrlen, data);
453 return 0;
454}
Herbert Xu90800212009-03-11 23:18:32 +0800455EXPORT_SYMBOL(nla_put);
Thomas Grafbfa83a92005-11-10 02:25:51 +0100456
Thomas Graffe4944e2006-08-04 23:03:05 -0700457/**
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
462 *
Thomas Grafbc3ed282008-06-03 16:36:54 -0700463 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
Thomas Graffe4944e2006-08-04 23:03:05 -0700464 * the attribute payload.
465 */
466int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
467{
468 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
Thomas Grafbc3ed282008-06-03 16:36:54 -0700469 return -EMSGSIZE;
Thomas Graffe4944e2006-08-04 23:03:05 -0700470
471 __nla_put_nohdr(skb, attrlen, data);
472 return 0;
473}
Herbert Xu90800212009-03-11 23:18:32 +0800474EXPORT_SYMBOL(nla_put_nohdr);
Thomas Grafbfa83a92005-11-10 02:25:51 +0100475
Patrick McHardy01480e12008-01-22 22:10:59 -0800476/**
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
481 *
Thomas Grafbc3ed282008-06-03 16:36:54 -0700482 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
Patrick McHardy01480e12008-01-22 22:10:59 -0800483 * the attribute payload.
484 */
485int nla_append(struct sk_buff *skb, int attrlen, const void *data)
486{
487 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
Thomas Grafbc3ed282008-06-03 16:36:54 -0700488 return -EMSGSIZE;
Patrick McHardy01480e12008-01-22 22:10:59 -0800489
490 memcpy(skb_put(skb, attrlen), data, attrlen);
491 return 0;
492}
Herbert Xu90800212009-03-11 23:18:32 +0800493EXPORT_SYMBOL(nla_append);
494#endif
Patrick McHardy01480e12008-01-22 22:10:59 -0800495
Thomas Grafbfa83a92005-11-10 02:25:51 +0100496EXPORT_SYMBOL(nla_validate);
Holger Eitzenbergere487eb92009-03-25 18:26:30 +0100497EXPORT_SYMBOL(nla_policy_len);
Thomas Grafbfa83a92005-11-10 02:25:51 +0100498EXPORT_SYMBOL(nla_parse);
499EXPORT_SYMBOL(nla_find);
500EXPORT_SYMBOL(nla_strlcpy);
Thomas Grafbfa83a92005-11-10 02:25:51 +0100501EXPORT_SYMBOL(nla_memcpy);
502EXPORT_SYMBOL(nla_memcmp);
503EXPORT_SYMBOL(nla_strcmp);