blob: 004139557e09507f01969754cc779002e1fcfbc9 [file] [log] [blame]
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
18static u16 nla_attr_minlen[NLA_TYPE_MAX+1] __read_mostly = {
19 [NLA_U8] = sizeof(u8),
20 [NLA_U16] = sizeof(u16),
21 [NLA_U32] = sizeof(u32),
22 [NLA_U64] = sizeof(u64),
Thomas Grafbfa83a92005-11-10 02:25:51 +010023 [NLA_NESTED] = NLA_HDRLEN,
24};
25
26static int validate_nla(struct nlattr *nla, int maxtype,
27 struct nla_policy *policy)
28{
29 struct nla_policy *pt;
Thomas Grafa5531a52006-08-26 20:11:47 -070030 int minlen = 0, attrlen = nla_len(nla);
Thomas Grafbfa83a92005-11-10 02:25:51 +010031
32 if (nla->nla_type <= 0 || nla->nla_type > maxtype)
33 return 0;
34
35 pt = &policy[nla->nla_type];
36
37 BUG_ON(pt->type > NLA_TYPE_MAX);
38
Thomas Grafa5531a52006-08-26 20:11:47 -070039 switch (pt->type) {
40 case NLA_FLAG:
41 if (attrlen > 0)
42 return -ERANGE;
43 break;
Thomas Grafbfa83a92005-11-10 02:25:51 +010044
Thomas Grafa5531a52006-08-26 20:11:47 -070045 case NLA_NUL_STRING:
46 if (pt->len)
47 minlen = min_t(int, attrlen, pt->len + 1);
48 else
49 minlen = attrlen;
Thomas Grafbfa83a92005-11-10 02:25:51 +010050
Thomas Grafa5531a52006-08-26 20:11:47 -070051 if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL)
52 return -EINVAL;
53 /* fall through */
54
55 case NLA_STRING:
56 if (attrlen < 1)
57 return -ERANGE;
58
59 if (pt->len) {
60 char *buf = nla_data(nla);
61
62 if (buf[attrlen - 1] == '\0')
63 attrlen--;
64
65 if (attrlen > pt->len)
66 return -ERANGE;
67 }
68 break;
69
70 default:
71 if (pt->len)
72 minlen = pt->len;
73 else if (pt->type != NLA_UNSPEC)
74 minlen = nla_attr_minlen[pt->type];
75
76 if (attrlen < minlen)
77 return -ERANGE;
78 }
Thomas Grafbfa83a92005-11-10 02:25:51 +010079
80 return 0;
81}
82
83/**
84 * nla_validate - Validate a stream of attributes
85 * @head: head of attribute stream
86 * @len: length of attribute stream
87 * @maxtype: maximum attribute type to be expected
88 * @policy: validation policy
89 *
90 * Validates all attributes in the specified attribute stream against the
91 * specified policy. Attributes with a type exceeding maxtype will be
92 * ignored. See documenation of struct nla_policy for more details.
93 *
94 * Returns 0 on success or a negative error code.
95 */
96int nla_validate(struct nlattr *head, int len, int maxtype,
97 struct nla_policy *policy)
98{
99 struct nlattr *nla;
100 int rem, err;
101
102 nla_for_each_attr(nla, head, len, rem) {
103 err = validate_nla(nla, maxtype, policy);
104 if (err < 0)
105 goto errout;
106 }
107
108 err = 0;
109errout:
110 return err;
111}
112
113/**
114 * nla_parse - Parse a stream of attributes into a tb buffer
115 * @tb: destination array with maxtype+1 elements
116 * @maxtype: maximum attribute type to be expected
117 * @head: head of attribute stream
118 * @len: length of attribute stream
119 *
120 * Parses a stream of attributes and stores a pointer to each attribute in
121 * the tb array accessable via the attribute type. Attributes with a type
122 * exceeding maxtype will be silently ignored for backwards compatibility
123 * reasons. policy may be set to NULL if no validation is required.
124 *
125 * Returns 0 on success or a negative error code.
126 */
127int nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head, int len,
128 struct nla_policy *policy)
129{
130 struct nlattr *nla;
131 int rem, err;
132
133 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
134
135 nla_for_each_attr(nla, head, len, rem) {
136 u16 type = nla->nla_type;
137
138 if (type > 0 && type <= maxtype) {
139 if (policy) {
140 err = validate_nla(nla, maxtype, policy);
141 if (err < 0)
142 goto errout;
143 }
144
145 tb[type] = nla;
146 }
147 }
148
149 if (unlikely(rem > 0))
150 printk(KERN_WARNING "netlink: %d bytes leftover after parsing "
151 "attributes.\n", rem);
152
153 err = 0;
154errout:
155 return err;
156}
157
158/**
159 * nla_find - Find a specific attribute in a stream of attributes
160 * @head: head of attribute stream
161 * @len: length of attribute stream
162 * @attrtype: type of attribute to look for
163 *
164 * Returns the first attribute in the stream matching the specified type.
165 */
166struct nlattr *nla_find(struct nlattr *head, int len, int attrtype)
167{
168 struct nlattr *nla;
169 int rem;
170
171 nla_for_each_attr(nla, head, len, rem)
172 if (nla->nla_type == attrtype)
173 return nla;
174
175 return NULL;
176}
177
178/**
179 * nla_strlcpy - Copy string attribute payload into a sized buffer
180 * @dst: where to copy the string to
181 * @src: attribute to copy the string from
182 * @dstsize: size of destination buffer
183 *
184 * Copies at most dstsize - 1 bytes into the destination buffer.
185 * The result is always a valid NUL-terminated string. Unlike
186 * strlcpy the destination buffer is always padded out.
187 *
188 * Returns the length of the source buffer.
189 */
190size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
191{
192 size_t srclen = nla_len(nla);
193 char *src = nla_data(nla);
194
195 if (srclen > 0 && src[srclen - 1] == '\0')
196 srclen--;
197
198 if (dstsize > 0) {
199 size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
200
201 memset(dst, 0, dstsize);
202 memcpy(dst, src, len);
203 }
204
205 return srclen;
206}
207
208/**
209 * nla_memcpy - Copy a netlink attribute into another memory area
210 * @dest: where to copy to memcpy
211 * @src: netlink attribute to copy from
212 * @count: size of the destination area
213 *
214 * Note: The number of bytes copied is limited by the length of
215 * attribute's payload. memcpy
216 *
217 * Returns the number of bytes copied.
218 */
219int nla_memcpy(void *dest, struct nlattr *src, int count)
220{
221 int minlen = min_t(int, count, nla_len(src));
222
223 memcpy(dest, nla_data(src), minlen);
224
225 return minlen;
226}
227
228/**
229 * nla_memcmp - Compare an attribute with sized memory area
230 * @nla: netlink attribute
231 * @data: memory area
232 * @size: size of memory area
233 */
234int nla_memcmp(const struct nlattr *nla, const void *data,
235 size_t size)
236{
237 int d = nla_len(nla) - size;
238
239 if (d == 0)
240 d = memcmp(nla_data(nla), data, size);
241
242 return d;
243}
244
245/**
246 * nla_strcmp - Compare a string attribute against a string
247 * @nla: netlink string attribute
248 * @str: another string
249 */
250int nla_strcmp(const struct nlattr *nla, const char *str)
251{
252 int len = strlen(str) + 1;
253 int d = nla_len(nla) - len;
254
255 if (d == 0)
256 d = memcmp(nla_data(nla), str, len);
257
258 return d;
259}
260
261/**
262 * __nla_reserve - reserve room for attribute on the skb
263 * @skb: socket buffer to reserve room on
264 * @attrtype: attribute type
265 * @attrlen: length of attribute payload
266 *
267 * Adds a netlink attribute header to a socket buffer and reserves
268 * room for the payload but does not copy it.
269 *
270 * The caller is responsible to ensure that the skb provides enough
271 * tailroom for the attribute header and payload.
272 */
273struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
274{
275 struct nlattr *nla;
276
277 nla = (struct nlattr *) skb_put(skb, nla_total_size(attrlen));
278 nla->nla_type = attrtype;
279 nla->nla_len = nla_attr_size(attrlen);
280
281 memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
282
283 return nla;
284}
285
286/**
Thomas Graffe4944e2006-08-04 23:03:05 -0700287 * __nla_reserve_nohdr - reserve room for attribute without header
288 * @skb: socket buffer to reserve room on
289 * @attrlen: length of attribute payload
290 *
291 * Reserves room for attribute payload without a header.
292 *
293 * The caller is responsible to ensure that the skb provides enough
294 * tailroom for the payload.
295 */
296void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
297{
298 void *start;
299
300 start = skb_put(skb, NLA_ALIGN(attrlen));
301 memset(start, 0, NLA_ALIGN(attrlen));
302
303 return start;
304}
305
306/**
Thomas Grafbfa83a92005-11-10 02:25:51 +0100307 * nla_reserve - reserve room for attribute on the skb
308 * @skb: socket buffer to reserve room on
309 * @attrtype: attribute type
310 * @attrlen: length of attribute payload
311 *
312 * Adds a netlink attribute header to a socket buffer and reserves
313 * room for the payload but does not copy it.
314 *
315 * Returns NULL if the tailroom of the skb is insufficient to store
316 * the attribute header and payload.
317 */
318struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
319{
320 if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
321 return NULL;
322
323 return __nla_reserve(skb, attrtype, attrlen);
324}
325
326/**
Thomas Graffe4944e2006-08-04 23:03:05 -0700327 * nla_reserve - reserve room for attribute without header
328 * @skb: socket buffer to reserve room on
329 * @len: length of attribute payload
330 *
331 * Reserves room for attribute payload without a header.
332 *
333 * Returns NULL if the tailroom of the skb is insufficient to store
334 * the attribute payload.
335 */
336void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
337{
338 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
339 return NULL;
340
341 return __nla_reserve_nohdr(skb, attrlen);
342}
343
344/**
Thomas Grafbfa83a92005-11-10 02:25:51 +0100345 * __nla_put - Add a netlink attribute to a socket buffer
346 * @skb: socket buffer to add attribute to
347 * @attrtype: attribute type
348 * @attrlen: length of attribute payload
349 * @data: head of attribute payload
350 *
351 * The caller is responsible to ensure that the skb provides enough
352 * tailroom for the attribute header and payload.
353 */
354void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
355 const void *data)
356{
357 struct nlattr *nla;
358
359 nla = __nla_reserve(skb, attrtype, attrlen);
360 memcpy(nla_data(nla), data, attrlen);
361}
362
Thomas Graffe4944e2006-08-04 23:03:05 -0700363/**
364 * __nla_put_nohdr - Add a netlink attribute without header
365 * @skb: socket buffer to add attribute to
366 * @attrlen: length of attribute payload
367 * @data: head of attribute payload
368 *
369 * The caller is responsible to ensure that the skb provides enough
370 * tailroom for the attribute payload.
371 */
372void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
373{
374 void *start;
375
376 start = __nla_reserve_nohdr(skb, attrlen);
377 memcpy(start, data, attrlen);
378}
Thomas Grafbfa83a92005-11-10 02:25:51 +0100379
380/**
381 * nla_put - Add a netlink attribute to a socket buffer
382 * @skb: socket buffer to add attribute to
383 * @attrtype: attribute type
384 * @attrlen: length of attribute payload
385 * @data: head of attribute payload
386 *
387 * Returns -1 if the tailroom of the skb is insufficient to store
388 * the attribute header and payload.
389 */
390int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
391{
392 if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
393 return -1;
394
395 __nla_put(skb, attrtype, attrlen, data);
396 return 0;
397}
398
Thomas Graffe4944e2006-08-04 23:03:05 -0700399/**
400 * nla_put_nohdr - Add a netlink attribute without header
401 * @skb: socket buffer to add attribute to
402 * @attrlen: length of attribute payload
403 * @data: head of attribute payload
404 *
405 * Returns -1 if the tailroom of the skb is insufficient to store
406 * the attribute payload.
407 */
408int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
409{
410 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
411 return -1;
412
413 __nla_put_nohdr(skb, attrlen, data);
414 return 0;
415}
Thomas Grafbfa83a92005-11-10 02:25:51 +0100416
417EXPORT_SYMBOL(nla_validate);
418EXPORT_SYMBOL(nla_parse);
419EXPORT_SYMBOL(nla_find);
420EXPORT_SYMBOL(nla_strlcpy);
421EXPORT_SYMBOL(__nla_reserve);
Thomas Graffe4944e2006-08-04 23:03:05 -0700422EXPORT_SYMBOL(__nla_reserve_nohdr);
Thomas Grafbfa83a92005-11-10 02:25:51 +0100423EXPORT_SYMBOL(nla_reserve);
Thomas Graffe4944e2006-08-04 23:03:05 -0700424EXPORT_SYMBOL(nla_reserve_nohdr);
Thomas Grafbfa83a92005-11-10 02:25:51 +0100425EXPORT_SYMBOL(__nla_put);
Thomas Graffe4944e2006-08-04 23:03:05 -0700426EXPORT_SYMBOL(__nla_put_nohdr);
Thomas Grafbfa83a92005-11-10 02:25:51 +0100427EXPORT_SYMBOL(nla_put);
Thomas Graffe4944e2006-08-04 23:03:05 -0700428EXPORT_SYMBOL(nla_put_nohdr);
Thomas Grafbfa83a92005-11-10 02:25:51 +0100429EXPORT_SYMBOL(nla_memcpy);
430EXPORT_SYMBOL(nla_memcmp);
431EXPORT_SYMBOL(nla_strcmp);