]>
Commit | Line | Data |
---|---|---|
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 | ||
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_NESTED] = NLA_HDRLEN, | |
24 | }; | |
25 | ||
26 | static int validate_nla(const 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 | */ | |
118 | int nla_validate(const struct nlattr *head, int len, int maxtype, | |
119 | const struct nla_policy *policy) | |
120 | { | |
121 | const 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; | |
131 | errout: | |
132 | return err; | |
133 | } | |
134 | ||
135 | /** | |
136 | * nla_policy_len - Determin the max. length of a policy | |
137 | * @policy: policy to use | |
138 | * @n: number of policies | |
139 | * | |
140 | * Determines the max. length of the policy. It is currently used | |
141 | * to allocated Netlink buffers roughly the size of the actual | |
142 | * message. | |
143 | * | |
144 | * Returns 0 on success or a negative error code. | |
145 | */ | |
146 | int | |
147 | nla_policy_len(const struct nla_policy *p, int n) | |
148 | { | |
149 | int i, len = 0; | |
150 | ||
151 | for (i = 0; i < n; i++) { | |
152 | if (p->len) | |
153 | len += nla_total_size(p->len); | |
154 | else if (nla_attr_minlen[p->type]) | |
155 | len += nla_total_size(nla_attr_minlen[p->type]); | |
156 | } | |
157 | ||
158 | return len; | |
159 | } | |
160 | ||
161 | /** | |
162 | * nla_parse - Parse a stream of attributes into a tb buffer | |
163 | * @tb: destination array with maxtype+1 elements | |
164 | * @maxtype: maximum attribute type to be expected | |
165 | * @head: head of attribute stream | |
166 | * @len: length of attribute stream | |
167 | * @policy: validation policy | |
168 | * | |
169 | * Parses a stream of attributes and stores a pointer to each attribute in | |
170 | * the tb array accessable via the attribute type. Attributes with a type | |
171 | * exceeding maxtype will be silently ignored for backwards compatibility | |
172 | * reasons. policy may be set to NULL if no validation is required. | |
173 | * | |
174 | * Returns 0 on success or a negative error code. | |
175 | */ | |
176 | int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head, | |
177 | int len, const struct nla_policy *policy) | |
178 | { | |
179 | const struct nlattr *nla; | |
180 | int rem, err; | |
181 | ||
182 | memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1)); | |
183 | ||
184 | nla_for_each_attr(nla, head, len, rem) { | |
185 | u16 type = nla_type(nla); | |
186 | ||
187 | if (type > 0 && type <= maxtype) { | |
188 | if (policy) { | |
189 | err = validate_nla(nla, maxtype, policy); | |
190 | if (err < 0) | |
191 | goto errout; | |
192 | } | |
193 | ||
194 | tb[type] = (struct nlattr *)nla; | |
195 | } | |
196 | } | |
197 | ||
198 | if (unlikely(rem > 0)) | |
199 | printk(KERN_WARNING "netlink: %d bytes leftover after parsing " | |
200 | "attributes.\n", rem); | |
201 | ||
202 | err = 0; | |
203 | errout: | |
204 | return err; | |
205 | } | |
206 | ||
207 | /** | |
208 | * nla_find - Find a specific attribute in a stream of attributes | |
209 | * @head: head of attribute stream | |
210 | * @len: length of attribute stream | |
211 | * @attrtype: type of attribute to look for | |
212 | * | |
213 | * Returns the first attribute in the stream matching the specified type. | |
214 | */ | |
215 | struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype) | |
216 | { | |
217 | const struct nlattr *nla; | |
218 | int rem; | |
219 | ||
220 | nla_for_each_attr(nla, head, len, rem) | |
221 | if (nla_type(nla) == attrtype) | |
222 | return (struct nlattr *)nla; | |
223 | ||
224 | return NULL; | |
225 | } | |
226 | ||
227 | /** | |
228 | * nla_strlcpy - Copy string attribute payload into a sized buffer | |
229 | * @dst: where to copy the string to | |
230 | * @nla: attribute to copy the string from | |
231 | * @dstsize: size of destination buffer | |
232 | * | |
233 | * Copies at most dstsize - 1 bytes into the destination buffer. | |
234 | * The result is always a valid NUL-terminated string. Unlike | |
235 | * strlcpy the destination buffer is always padded out. | |
236 | * | |
237 | * Returns the length of the source buffer. | |
238 | */ | |
239 | size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize) | |
240 | { | |
241 | size_t srclen = nla_len(nla); | |
242 | char *src = nla_data(nla); | |
243 | ||
244 | if (srclen > 0 && src[srclen - 1] == '\0') | |
245 | srclen--; | |
246 | ||
247 | if (dstsize > 0) { | |
248 | size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen; | |
249 | ||
250 | memset(dst, 0, dstsize); | |
251 | memcpy(dst, src, len); | |
252 | } | |
253 | ||
254 | return srclen; | |
255 | } | |
256 | ||
257 | /** | |
258 | * nla_memcpy - Copy a netlink attribute into another memory area | |
259 | * @dest: where to copy to memcpy | |
260 | * @src: netlink attribute to copy from | |
261 | * @count: size of the destination area | |
262 | * | |
263 | * Note: The number of bytes copied is limited by the length of | |
264 | * attribute's payload. memcpy | |
265 | * | |
266 | * Returns the number of bytes copied. | |
267 | */ | |
268 | int nla_memcpy(void *dest, const struct nlattr *src, int count) | |
269 | { | |
270 | int minlen = min_t(int, count, nla_len(src)); | |
271 | ||
272 | memcpy(dest, nla_data(src), minlen); | |
273 | ||
274 | return minlen; | |
275 | } | |
276 | ||
277 | /** | |
278 | * nla_memcmp - Compare an attribute with sized memory area | |
279 | * @nla: netlink attribute | |
280 | * @data: memory area | |
281 | * @size: size of memory area | |
282 | */ | |
283 | int nla_memcmp(const struct nlattr *nla, const void *data, | |
284 | size_t size) | |
285 | { | |
286 | int d = nla_len(nla) - size; | |
287 | ||
288 | if (d == 0) | |
289 | d = memcmp(nla_data(nla), data, size); | |
290 | ||
291 | return d; | |
292 | } | |
293 | ||
294 | /** | |
295 | * nla_strcmp - Compare a string attribute against a string | |
296 | * @nla: netlink string attribute | |
297 | * @str: another string | |
298 | */ | |
299 | int nla_strcmp(const struct nlattr *nla, const char *str) | |
300 | { | |
301 | int len = strlen(str) + 1; | |
302 | int d = nla_len(nla) - len; | |
303 | ||
304 | if (d == 0) | |
305 | d = memcmp(nla_data(nla), str, len); | |
306 | ||
307 | return d; | |
308 | } | |
309 | ||
310 | #ifdef CONFIG_NET | |
311 | /** | |
312 | * __nla_reserve - reserve room for attribute on the skb | |
313 | * @skb: socket buffer to reserve room on | |
314 | * @attrtype: attribute type | |
315 | * @attrlen: length of attribute payload | |
316 | * | |
317 | * Adds a netlink attribute header to a socket buffer and reserves | |
318 | * room for the payload but does not copy it. | |
319 | * | |
320 | * The caller is responsible to ensure that the skb provides enough | |
321 | * tailroom for the attribute header and payload. | |
322 | */ | |
323 | struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen) | |
324 | { | |
325 | struct nlattr *nla; | |
326 | ||
327 | nla = (struct nlattr *) skb_put(skb, nla_total_size(attrlen)); | |
328 | nla->nla_type = attrtype; | |
329 | nla->nla_len = nla_attr_size(attrlen); | |
330 | ||
331 | memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen)); | |
332 | ||
333 | return nla; | |
334 | } | |
335 | EXPORT_SYMBOL(__nla_reserve); | |
336 | ||
337 | /** | |
338 | * __nla_reserve_nohdr - reserve room for attribute without header | |
339 | * @skb: socket buffer to reserve room on | |
340 | * @attrlen: length of attribute payload | |
341 | * | |
342 | * Reserves room for attribute payload without a header. | |
343 | * | |
344 | * The caller is responsible to ensure that the skb provides enough | |
345 | * tailroom for the payload. | |
346 | */ | |
347 | void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen) | |
348 | { | |
349 | void *start; | |
350 | ||
351 | start = skb_put(skb, NLA_ALIGN(attrlen)); | |
352 | memset(start, 0, NLA_ALIGN(attrlen)); | |
353 | ||
354 | return start; | |
355 | } | |
356 | EXPORT_SYMBOL(__nla_reserve_nohdr); | |
357 | ||
358 | /** | |
359 | * nla_reserve - reserve room for attribute on the skb | |
360 | * @skb: socket buffer to reserve room on | |
361 | * @attrtype: attribute type | |
362 | * @attrlen: length of attribute payload | |
363 | * | |
364 | * Adds a netlink attribute header to a socket buffer and reserves | |
365 | * room for the payload but does not copy it. | |
366 | * | |
367 | * Returns NULL if the tailroom of the skb is insufficient to store | |
368 | * the attribute header and payload. | |
369 | */ | |
370 | struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen) | |
371 | { | |
372 | if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen))) | |
373 | return NULL; | |
374 | ||
375 | return __nla_reserve(skb, attrtype, attrlen); | |
376 | } | |
377 | EXPORT_SYMBOL(nla_reserve); | |
378 | ||
379 | /** | |
380 | * nla_reserve_nohdr - reserve room for attribute without header | |
381 | * @skb: socket buffer to reserve room on | |
382 | * @attrlen: length of attribute payload | |
383 | * | |
384 | * Reserves room for attribute payload without a header. | |
385 | * | |
386 | * Returns NULL if the tailroom of the skb is insufficient to store | |
387 | * the attribute payload. | |
388 | */ | |
389 | void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen) | |
390 | { | |
391 | if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen))) | |
392 | return NULL; | |
393 | ||
394 | return __nla_reserve_nohdr(skb, attrlen); | |
395 | } | |
396 | EXPORT_SYMBOL(nla_reserve_nohdr); | |
397 | ||
398 | /** | |
399 | * __nla_put - Add a netlink attribute to a socket buffer | |
400 | * @skb: socket buffer to add attribute to | |
401 | * @attrtype: attribute type | |
402 | * @attrlen: length of attribute payload | |
403 | * @data: head of attribute payload | |
404 | * | |
405 | * The caller is responsible to ensure that the skb provides enough | |
406 | * tailroom for the attribute header and payload. | |
407 | */ | |
408 | void __nla_put(struct sk_buff *skb, int attrtype, int attrlen, | |
409 | const void *data) | |
410 | { | |
411 | struct nlattr *nla; | |
412 | ||
413 | nla = __nla_reserve(skb, attrtype, attrlen); | |
414 | memcpy(nla_data(nla), data, attrlen); | |
415 | } | |
416 | EXPORT_SYMBOL(__nla_put); | |
417 | ||
418 | /** | |
419 | * __nla_put_nohdr - Add a netlink attribute without header | |
420 | * @skb: socket buffer to add attribute to | |
421 | * @attrlen: length of attribute payload | |
422 | * @data: head of attribute payload | |
423 | * | |
424 | * The caller is responsible to ensure that the skb provides enough | |
425 | * tailroom for the attribute payload. | |
426 | */ | |
427 | void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data) | |
428 | { | |
429 | void *start; | |
430 | ||
431 | start = __nla_reserve_nohdr(skb, attrlen); | |
432 | memcpy(start, data, attrlen); | |
433 | } | |
434 | EXPORT_SYMBOL(__nla_put_nohdr); | |
435 | ||
436 | /** | |
437 | * nla_put - Add a netlink attribute to a socket buffer | |
438 | * @skb: socket buffer to add attribute to | |
439 | * @attrtype: attribute type | |
440 | * @attrlen: length of attribute payload | |
441 | * @data: head of attribute payload | |
442 | * | |
443 | * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store | |
444 | * the attribute header and payload. | |
445 | */ | |
446 | int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data) | |
447 | { | |
448 | if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen))) | |
449 | return -EMSGSIZE; | |
450 | ||
451 | __nla_put(skb, attrtype, attrlen, data); | |
452 | return 0; | |
453 | } | |
454 | EXPORT_SYMBOL(nla_put); | |
455 | ||
456 | /** | |
457 | * nla_put_nohdr - Add a netlink attribute without header | |
458 | * @skb: socket buffer to add attribute to | |
459 | * @attrlen: length of attribute payload | |
460 | * @data: head of attribute payload | |
461 | * | |
462 | * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store | |
463 | * the attribute payload. | |
464 | */ | |
465 | int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data) | |
466 | { | |
467 | if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen))) | |
468 | return -EMSGSIZE; | |
469 | ||
470 | __nla_put_nohdr(skb, attrlen, data); | |
471 | return 0; | |
472 | } | |
473 | EXPORT_SYMBOL(nla_put_nohdr); | |
474 | ||
475 | /** | |
476 | * nla_append - Add a netlink attribute without header or padding | |
477 | * @skb: socket buffer to add attribute to | |
478 | * @attrlen: length of attribute payload | |
479 | * @data: head of attribute payload | |
480 | * | |
481 | * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store | |
482 | * the attribute payload. | |
483 | */ | |
484 | int nla_append(struct sk_buff *skb, int attrlen, const void *data) | |
485 | { | |
486 | if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen))) | |
487 | return -EMSGSIZE; | |
488 | ||
489 | memcpy(skb_put(skb, attrlen), data, attrlen); | |
490 | return 0; | |
491 | } | |
492 | EXPORT_SYMBOL(nla_append); | |
493 | #endif | |
494 | ||
495 | EXPORT_SYMBOL(nla_validate); | |
496 | EXPORT_SYMBOL(nla_policy_len); | |
497 | EXPORT_SYMBOL(nla_parse); | |
498 | EXPORT_SYMBOL(nla_find); | |
499 | EXPORT_SYMBOL(nla_strlcpy); | |
500 | EXPORT_SYMBOL(nla_memcpy); | |
501 | EXPORT_SYMBOL(nla_memcmp); | |
502 | EXPORT_SYMBOL(nla_strcmp); |