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-rw-r--r--lib/nlattr.c475
1 files changed, 475 insertions, 0 deletions
diff --git a/lib/nlattr.c b/lib/nlattr.c
new file mode 100644
index 000000000000..80009a24e21d
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@@ -0,0 +1,475 @@
1/*
2 * NETLINK Netlink attributes
3 *
4 * Authors: Thomas Graf <tgraf@suug.ch>
5 * Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
6 */
7
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>
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),
23 [NLA_NESTED] = NLA_HDRLEN,
24};
25
26static int validate_nla(struct nlattr *nla, int maxtype,
27 const struct nla_policy *policy)
28{
29 const struct nla_policy *pt;
30 int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
31
32 if (type <= 0 || type > maxtype)
33 return 0;
34
35 pt = &policy[type];
36
37 BUG_ON(pt->type > NLA_TYPE_MAX);
38
39 switch (pt->type) {
40 case NLA_FLAG:
41 if (attrlen > 0)
42 return -ERANGE;
43 break;
44
45 case NLA_NUL_STRING:
46 if (pt->len)
47 minlen = min_t(int, attrlen, pt->len + 1);
48 else
49 minlen = attrlen;
50
51 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 case NLA_BINARY:
71 if (pt->len && attrlen > pt->len)
72 return -ERANGE;
73 break;
74
75 case NLA_NESTED_COMPAT:
76 if (attrlen < pt->len)
77 return -ERANGE;
78 if (attrlen < NLA_ALIGN(pt->len))
79 break;
80 if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN)
81 return -ERANGE;
82 nla = nla_data(nla) + NLA_ALIGN(pt->len);
83 if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN + nla_len(nla))
84 return -ERANGE;
85 break;
86 case NLA_NESTED:
87 /* a nested attributes is allowed to be empty; if its not,
88 * it must have a size of at least NLA_HDRLEN.
89 */
90 if (attrlen == 0)
91 break;
92 default:
93 if (pt->len)
94 minlen = pt->len;
95 else if (pt->type != NLA_UNSPEC)
96 minlen = nla_attr_minlen[pt->type];
97
98 if (attrlen < minlen)
99 return -ERANGE;
100 }
101
102 return 0;
103}
104
105/**
106 * nla_validate - Validate a stream of attributes
107 * @head: head of attribute stream
108 * @len: length of attribute stream
109 * @maxtype: maximum attribute type to be expected
110 * @policy: validation policy
111 *
112 * Validates all attributes in the specified attribute stream against the
113 * specified policy. Attributes with a type exceeding maxtype will be
114 * ignored. See documenation of struct nla_policy for more details.
115 *
116 * Returns 0 on success or a negative error code.
117 */
118int nla_validate(struct nlattr *head, int len, int maxtype,
119 const struct nla_policy *policy)
120{
121 struct nlattr *nla;
122 int rem, err;
123
124 nla_for_each_attr(nla, head, len, rem) {
125 err = validate_nla(nla, maxtype, policy);
126 if (err < 0)
127 goto errout;
128 }
129
130 err = 0;
131errout:
132 return err;
133}
134
135/**
136 * nla_parse - Parse a stream of attributes into a tb buffer
137 * @tb: destination array with maxtype+1 elements
138 * @maxtype: maximum attribute type to be expected
139 * @head: head of attribute stream
140 * @len: length of attribute stream
141 * @policy: validation policy
142 *
143 * Parses a stream of attributes and stores a pointer to each attribute in
144 * the tb array accessable via the attribute type. Attributes with a type
145 * exceeding maxtype will be silently ignored for backwards compatibility
146 * reasons. policy may be set to NULL if no validation is required.
147 *
148 * Returns 0 on success or a negative error code.
149 */
150int nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head, int len,
151 const struct nla_policy *policy)
152{
153 struct nlattr *nla;
154 int rem, err;
155
156 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
157
158 nla_for_each_attr(nla, head, len, rem) {
159 u16 type = nla_type(nla);
160
161 if (type > 0 && type <= maxtype) {
162 if (policy) {
163 err = validate_nla(nla, maxtype, policy);
164 if (err < 0)
165 goto errout;
166 }
167
168 tb[type] = nla;
169 }
170 }
171
172 if (unlikely(rem > 0))
173 printk(KERN_WARNING "netlink: %d bytes leftover after parsing "
174 "attributes.\n", rem);
175
176 err = 0;
177errout:
178 return err;
179}
180
181/**
182 * nla_find - Find a specific attribute in a stream of attributes
183 * @head: head of attribute stream
184 * @len: length of attribute stream
185 * @attrtype: type of attribute to look for
186 *
187 * Returns the first attribute in the stream matching the specified type.
188 */
189struct nlattr *nla_find(struct nlattr *head, int len, int attrtype)
190{
191 struct nlattr *nla;
192 int rem;
193
194 nla_for_each_attr(nla, head, len, rem)
195 if (nla_type(nla) == attrtype)
196 return nla;
197
198 return NULL;
199}
200
201/**
202 * nla_strlcpy - Copy string attribute payload into a sized buffer
203 * @dst: where to copy the string to
204 * @nla: attribute to copy the string from
205 * @dstsize: size of destination buffer
206 *
207 * Copies at most dstsize - 1 bytes into the destination buffer.
208 * The result is always a valid NUL-terminated string. Unlike
209 * strlcpy the destination buffer is always padded out.
210 *
211 * Returns the length of the source buffer.
212 */
213size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
214{
215 size_t srclen = nla_len(nla);
216 char *src = nla_data(nla);
217
218 if (srclen > 0 && src[srclen - 1] == '\0')
219 srclen--;
220
221 if (dstsize > 0) {
222 size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
223
224 memset(dst, 0, dstsize);
225 memcpy(dst, src, len);
226 }
227
228 return srclen;
229}
230
231/**
232 * nla_memcpy - Copy a netlink attribute into another memory area
233 * @dest: where to copy to memcpy
234 * @src: netlink attribute to copy from
235 * @count: size of the destination area
236 *
237 * Note: The number of bytes copied is limited by the length of
238 * attribute's payload. memcpy
239 *
240 * Returns the number of bytes copied.
241 */
242int nla_memcpy(void *dest, const struct nlattr *src, int count)
243{
244 int minlen = min_t(int, count, nla_len(src));
245
246 memcpy(dest, nla_data(src), minlen);
247
248 return minlen;
249}
250
251/**
252 * nla_memcmp - Compare an attribute with sized memory area
253 * @nla: netlink attribute
254 * @data: memory area
255 * @size: size of memory area
256 */
257int nla_memcmp(const struct nlattr *nla, const void *data,
258 size_t size)
259{
260 int d = nla_len(nla) - size;
261
262 if (d == 0)
263 d = memcmp(nla_data(nla), data, size);
264
265 return d;
266}
267
268/**
269 * nla_strcmp - Compare a string attribute against a string
270 * @nla: netlink string attribute
271 * @str: another string
272 */
273int nla_strcmp(const struct nlattr *nla, const char *str)
274{
275 int len = strlen(str) + 1;
276 int d = nla_len(nla) - len;
277
278 if (d == 0)
279 d = memcmp(nla_data(nla), str, len);
280
281 return d;
282}
283
284#ifdef CONFIG_NET
285/**
286 * __nla_reserve - reserve room for attribute on the skb
287 * @skb: socket buffer to reserve room on
288 * @attrtype: attribute type
289 * @attrlen: length of attribute payload
290 *
291 * Adds a netlink attribute header to a socket buffer and reserves
292 * room for the payload but does not copy it.
293 *
294 * The caller is responsible to ensure that the skb provides enough
295 * tailroom for the attribute header and payload.
296 */
297struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
298{
299 struct nlattr *nla;
300
301 nla = (struct nlattr *) skb_put(skb, nla_total_size(attrlen));
302 nla->nla_type = attrtype;
303 nla->nla_len = nla_attr_size(attrlen);
304
305 memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
306
307 return nla;
308}
309EXPORT_SYMBOL(__nla_reserve);
310
311/**
312 * __nla_reserve_nohdr - reserve room for attribute without header
313 * @skb: socket buffer to reserve room on
314 * @attrlen: length of attribute payload
315 *
316 * Reserves room for attribute payload without a header.
317 *
318 * The caller is responsible to ensure that the skb provides enough
319 * tailroom for the payload.
320 */
321void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
322{
323 void *start;
324
325 start = skb_put(skb, NLA_ALIGN(attrlen));
326 memset(start, 0, NLA_ALIGN(attrlen));
327
328 return start;
329}
330EXPORT_SYMBOL(__nla_reserve_nohdr);
331
332/**
333 * nla_reserve - reserve room for attribute on the skb
334 * @skb: socket buffer to reserve room on
335 * @attrtype: attribute type
336 * @attrlen: length of attribute payload
337 *
338 * Adds a netlink attribute header to a socket buffer and reserves
339 * room for the payload but does not copy it.
340 *
341 * Returns NULL if the tailroom of the skb is insufficient to store
342 * the attribute header and payload.
343 */
344struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
345{
346 if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
347 return NULL;
348
349 return __nla_reserve(skb, attrtype, attrlen);
350}
351EXPORT_SYMBOL(nla_reserve);
352
353/**
354 * nla_reserve_nohdr - reserve room for attribute without header
355 * @skb: socket buffer to reserve room on
356 * @attrlen: length of attribute payload
357 *
358 * Reserves room for attribute payload without a header.
359 *
360 * Returns NULL if the tailroom of the skb is insufficient to store
361 * the attribute payload.
362 */
363void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
364{
365 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
366 return NULL;
367
368 return __nla_reserve_nohdr(skb, attrlen);
369}
370EXPORT_SYMBOL(nla_reserve_nohdr);
371
372/**
373 * __nla_put - Add a netlink attribute to a socket buffer
374 * @skb: socket buffer to add attribute to
375 * @attrtype: attribute type
376 * @attrlen: length of attribute payload
377 * @data: head of attribute payload
378 *
379 * The caller is responsible to ensure that the skb provides enough
380 * tailroom for the attribute header and payload.
381 */
382void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
383 const void *data)
384{
385 struct nlattr *nla;
386
387 nla = __nla_reserve(skb, attrtype, attrlen);
388 memcpy(nla_data(nla), data, attrlen);
389}
390EXPORT_SYMBOL(__nla_put);
391
392/**
393 * __nla_put_nohdr - Add a netlink attribute without header
394 * @skb: socket buffer to add attribute to
395 * @attrlen: length of attribute payload
396 * @data: head of attribute payload
397 *
398 * The caller is responsible to ensure that the skb provides enough
399 * tailroom for the attribute payload.
400 */
401void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
402{
403 void *start;
404
405 start = __nla_reserve_nohdr(skb, attrlen);
406 memcpy(start, data, attrlen);
407}
408EXPORT_SYMBOL(__nla_put_nohdr);
409
410/**
411 * nla_put - Add a netlink attribute to a socket buffer
412 * @skb: socket buffer to add attribute to
413 * @attrtype: attribute type
414 * @attrlen: length of attribute payload
415 * @data: head of attribute payload
416 *
417 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
418 * the attribute header and payload.
419 */
420int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
421{
422 if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
423 return -EMSGSIZE;
424
425 __nla_put(skb, attrtype, attrlen, data);
426 return 0;
427}
428EXPORT_SYMBOL(nla_put);
429
430/**
431 * nla_put_nohdr - Add a netlink attribute without header
432 * @skb: socket buffer to add attribute to
433 * @attrlen: length of attribute payload
434 * @data: head of attribute payload
435 *
436 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
437 * the attribute payload.
438 */
439int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
440{
441 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
442 return -EMSGSIZE;
443
444 __nla_put_nohdr(skb, attrlen, data);
445 return 0;
446}
447EXPORT_SYMBOL(nla_put_nohdr);
448
449/**
450 * nla_append - Add a netlink attribute without header or padding
451 * @skb: socket buffer to add attribute to
452 * @attrlen: length of attribute payload
453 * @data: head of attribute payload
454 *
455 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
456 * the attribute payload.
457 */
458int nla_append(struct sk_buff *skb, int attrlen, const void *data)
459{
460 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
461 return -EMSGSIZE;
462
463 memcpy(skb_put(skb, attrlen), data, attrlen);
464 return 0;
465}
466EXPORT_SYMBOL(nla_append);
467#endif
468
469EXPORT_SYMBOL(nla_validate);
470EXPORT_SYMBOL(nla_parse);
471EXPORT_SYMBOL(nla_find);
472EXPORT_SYMBOL(nla_strlcpy);
473EXPORT_SYMBOL(nla_memcpy);
474EXPORT_SYMBOL(nla_memcmp);
475EXPORT_SYMBOL(nla_strcmp);