]>
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/export.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_MSECS] = sizeof(u64), | |
24 | [NLA_NESTED] = NLA_HDRLEN, | |
25 | [NLA_S8] = sizeof(s8), | |
26 | [NLA_S16] = sizeof(s16), | |
27 | [NLA_S32] = sizeof(s32), | |
28 | [NLA_S64] = sizeof(s64), | |
29 | }; | |
30 | ||
31 | static int validate_nla(const struct nlattr *nla, int maxtype, | |
32 | const struct nla_policy *policy) | |
33 | { | |
34 | const struct nla_policy *pt; | |
35 | int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla); | |
36 | ||
37 | if (type <= 0 || type > maxtype) | |
38 | return 0; | |
39 | ||
40 | pt = &policy[type]; | |
41 | ||
42 | BUG_ON(pt->type > NLA_TYPE_MAX); | |
43 | ||
44 | switch (pt->type) { | |
45 | case NLA_FLAG: | |
46 | if (attrlen > 0) | |
47 | return -ERANGE; | |
48 | break; | |
49 | ||
50 | case NLA_NUL_STRING: | |
51 | if (pt->len) | |
52 | minlen = min_t(int, attrlen, pt->len + 1); | |
53 | else | |
54 | minlen = attrlen; | |
55 | ||
56 | if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL) | |
57 | return -EINVAL; | |
58 | /* fall through */ | |
59 | ||
60 | case NLA_STRING: | |
61 | if (attrlen < 1) | |
62 | return -ERANGE; | |
63 | ||
64 | if (pt->len) { | |
65 | char *buf = nla_data(nla); | |
66 | ||
67 | if (buf[attrlen - 1] == '\0') | |
68 | attrlen--; | |
69 | ||
70 | if (attrlen > pt->len) | |
71 | return -ERANGE; | |
72 | } | |
73 | break; | |
74 | ||
75 | case NLA_BINARY: | |
76 | if (pt->len && attrlen > pt->len) | |
77 | return -ERANGE; | |
78 | break; | |
79 | ||
80 | case NLA_NESTED_COMPAT: | |
81 | if (attrlen < pt->len) | |
82 | return -ERANGE; | |
83 | if (attrlen < NLA_ALIGN(pt->len)) | |
84 | break; | |
85 | if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN) | |
86 | return -ERANGE; | |
87 | nla = nla_data(nla) + NLA_ALIGN(pt->len); | |
88 | if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN + nla_len(nla)) | |
89 | return -ERANGE; | |
90 | break; | |
91 | case NLA_NESTED: | |
92 | /* a nested attributes is allowed to be empty; if its not, | |
93 | * it must have a size of at least NLA_HDRLEN. | |
94 | */ | |
95 | if (attrlen == 0) | |
96 | break; | |
97 | default: | |
98 | if (pt->len) | |
99 | minlen = pt->len; | |
100 | else if (pt->type != NLA_UNSPEC) | |
101 | minlen = nla_attr_minlen[pt->type]; | |
102 | ||
103 | if (attrlen < minlen) | |
104 | return -ERANGE; | |
105 | } | |
106 | ||
107 | return 0; | |
108 | } | |
109 | ||
110 | /** | |
111 | * nla_validate - Validate a stream of attributes | |
112 | * @head: head of attribute stream | |
113 | * @len: length of attribute stream | |
114 | * @maxtype: maximum attribute type to be expected | |
115 | * @policy: validation policy | |
116 | * | |
117 | * Validates all attributes in the specified attribute stream against the | |
118 | * specified policy. Attributes with a type exceeding maxtype will be | |
119 | * ignored. See documenation of struct nla_policy for more details. | |
120 | * | |
121 | * Returns 0 on success or a negative error code. | |
122 | */ | |
123 | int nla_validate(const struct nlattr *head, int len, int maxtype, | |
124 | const struct nla_policy *policy) | |
125 | { | |
126 | const struct nlattr *nla; | |
127 | int rem, err; | |
128 | ||
129 | nla_for_each_attr(nla, head, len, rem) { | |
130 | err = validate_nla(nla, maxtype, policy); | |
131 | if (err < 0) | |
132 | goto errout; | |
133 | } | |
134 | ||
135 | err = 0; | |
136 | errout: | |
137 | return err; | |
138 | } | |
139 | ||
140 | /** | |
141 | * nla_policy_len - Determin the max. length of a policy | |
142 | * @policy: policy to use | |
143 | * @n: number of policies | |
144 | * | |
145 | * Determines the max. length of the policy. It is currently used | |
146 | * to allocated Netlink buffers roughly the size of the actual | |
147 | * message. | |
148 | * | |
149 | * Returns 0 on success or a negative error code. | |
150 | */ | |
151 | int | |
152 | nla_policy_len(const struct nla_policy *p, int n) | |
153 | { | |
154 | int i, len = 0; | |
155 | ||
156 | for (i = 0; i < n; i++, p++) { | |
157 | if (p->len) | |
158 | len += nla_total_size(p->len); | |
159 | else if (nla_attr_minlen[p->type]) | |
160 | len += nla_total_size(nla_attr_minlen[p->type]); | |
161 | } | |
162 | ||
163 | return len; | |
164 | } | |
165 | ||
166 | /** | |
167 | * nla_parse - Parse a stream of attributes into a tb buffer | |
168 | * @tb: destination array with maxtype+1 elements | |
169 | * @maxtype: maximum attribute type to be expected | |
170 | * @head: head of attribute stream | |
171 | * @len: length of attribute stream | |
172 | * @policy: validation policy | |
173 | * | |
174 | * Parses a stream of attributes and stores a pointer to each attribute in | |
175 | * the tb array accessible via the attribute type. Attributes with a type | |
176 | * exceeding maxtype will be silently ignored for backwards compatibility | |
177 | * reasons. policy may be set to NULL if no validation is required. | |
178 | * | |
179 | * Returns 0 on success or a negative error code. | |
180 | */ | |
181 | int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head, | |
182 | int len, const struct nla_policy *policy) | |
183 | { | |
184 | const struct nlattr *nla; | |
185 | int rem, err; | |
186 | ||
187 | memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1)); | |
188 | ||
189 | nla_for_each_attr(nla, head, len, rem) { | |
190 | u16 type = nla_type(nla); | |
191 | ||
192 | if (type > 0 && type <= maxtype) { | |
193 | if (policy) { | |
194 | err = validate_nla(nla, maxtype, policy); | |
195 | if (err < 0) | |
196 | goto errout; | |
197 | } | |
198 | ||
199 | tb[type] = (struct nlattr *)nla; | |
200 | } | |
201 | } | |
202 | ||
203 | if (unlikely(rem > 0)) | |
204 | printk(KERN_WARNING "netlink: %d bytes leftover after parsing " | |
205 | "attributes.\n", rem); | |
206 | ||
207 | err = 0; | |
208 | errout: | |
209 | return err; | |
210 | } | |
211 | ||
212 | /** | |
213 | * nla_find - Find a specific attribute in a stream of attributes | |
214 | * @head: head of attribute stream | |
215 | * @len: length of attribute stream | |
216 | * @attrtype: type of attribute to look for | |
217 | * | |
218 | * Returns the first attribute in the stream matching the specified type. | |
219 | */ | |
220 | struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype) | |
221 | { | |
222 | const struct nlattr *nla; | |
223 | int rem; | |
224 | ||
225 | nla_for_each_attr(nla, head, len, rem) | |
226 | if (nla_type(nla) == attrtype) | |
227 | return (struct nlattr *)nla; | |
228 | ||
229 | return NULL; | |
230 | } | |
231 | ||
232 | /** | |
233 | * nla_strlcpy - Copy string attribute payload into a sized buffer | |
234 | * @dst: where to copy the string to | |
235 | * @nla: attribute to copy the string from | |
236 | * @dstsize: size of destination buffer | |
237 | * | |
238 | * Copies at most dstsize - 1 bytes into the destination buffer. | |
239 | * The result is always a valid NUL-terminated string. Unlike | |
240 | * strlcpy the destination buffer is always padded out. | |
241 | * | |
242 | * Returns the length of the source buffer. | |
243 | */ | |
244 | size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize) | |
245 | { | |
246 | size_t srclen = nla_len(nla); | |
247 | char *src = nla_data(nla); | |
248 | ||
249 | if (srclen > 0 && src[srclen - 1] == '\0') | |
250 | srclen--; | |
251 | ||
252 | if (dstsize > 0) { | |
253 | size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen; | |
254 | ||
255 | memset(dst, 0, dstsize); | |
256 | memcpy(dst, src, len); | |
257 | } | |
258 | ||
259 | return srclen; | |
260 | } | |
261 | ||
262 | /** | |
263 | * nla_memcpy - Copy a netlink attribute into another memory area | |
264 | * @dest: where to copy to memcpy | |
265 | * @src: netlink attribute to copy from | |
266 | * @count: size of the destination area | |
267 | * | |
268 | * Note: The number of bytes copied is limited by the length of | |
269 | * attribute's payload. memcpy | |
270 | * | |
271 | * Returns the number of bytes copied. | |
272 | */ | |
273 | int nla_memcpy(void *dest, const struct nlattr *src, int count) | |
274 | { | |
275 | int minlen = min_t(int, count, nla_len(src)); | |
276 | ||
277 | memcpy(dest, nla_data(src), minlen); | |
278 | ||
279 | return minlen; | |
280 | } | |
281 | ||
282 | /** | |
283 | * nla_memcmp - Compare an attribute with sized memory area | |
284 | * @nla: netlink attribute | |
285 | * @data: memory area | |
286 | * @size: size of memory area | |
287 | */ | |
288 | int nla_memcmp(const struct nlattr *nla, const void *data, | |
289 | size_t size) | |
290 | { | |
291 | int d = nla_len(nla) - size; | |
292 | ||
293 | if (d == 0) | |
294 | d = memcmp(nla_data(nla), data, size); | |
295 | ||
296 | return d; | |
297 | } | |
298 | ||
299 | /** | |
300 | * nla_strcmp - Compare a string attribute against a string | |
301 | * @nla: netlink string attribute | |
302 | * @str: another string | |
303 | */ | |
304 | int nla_strcmp(const struct nlattr *nla, const char *str) | |
305 | { | |
306 | int len = strlen(str); | |
307 | char *buf = nla_data(nla); | |
308 | int attrlen = nla_len(nla); | |
309 | int d; | |
310 | ||
311 | if (attrlen > 0 && buf[attrlen - 1] == '\0') | |
312 | attrlen--; | |
313 | ||
314 | d = attrlen - len; | |
315 | if (d == 0) | |
316 | d = memcmp(nla_data(nla), str, len); | |
317 | ||
318 | return d; | |
319 | } | |
320 | ||
321 | #ifdef CONFIG_NET | |
322 | /** | |
323 | * __nla_reserve - reserve room for attribute on the skb | |
324 | * @skb: socket buffer to reserve room on | |
325 | * @attrtype: attribute type | |
326 | * @attrlen: length of attribute payload | |
327 | * | |
328 | * Adds a netlink attribute header to a socket buffer and reserves | |
329 | * room for the payload but does not copy it. | |
330 | * | |
331 | * The caller is responsible to ensure that the skb provides enough | |
332 | * tailroom for the attribute header and payload. | |
333 | */ | |
334 | struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen) | |
335 | { | |
336 | struct nlattr *nla; | |
337 | ||
338 | nla = (struct nlattr *) skb_put(skb, nla_total_size(attrlen)); | |
339 | nla->nla_type = attrtype; | |
340 | nla->nla_len = nla_attr_size(attrlen); | |
341 | ||
342 | memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen)); | |
343 | ||
344 | return nla; | |
345 | } | |
346 | EXPORT_SYMBOL(__nla_reserve); | |
347 | ||
348 | /** | |
349 | * __nla_reserve_nohdr - reserve room for attribute without header | |
350 | * @skb: socket buffer to reserve room on | |
351 | * @attrlen: length of attribute payload | |
352 | * | |
353 | * Reserves room for attribute payload without a header. | |
354 | * | |
355 | * The caller is responsible to ensure that the skb provides enough | |
356 | * tailroom for the payload. | |
357 | */ | |
358 | void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen) | |
359 | { | |
360 | void *start; | |
361 | ||
362 | start = skb_put(skb, NLA_ALIGN(attrlen)); | |
363 | memset(start, 0, NLA_ALIGN(attrlen)); | |
364 | ||
365 | return start; | |
366 | } | |
367 | EXPORT_SYMBOL(__nla_reserve_nohdr); | |
368 | ||
369 | /** | |
370 | * nla_reserve - reserve room for attribute on the skb | |
371 | * @skb: socket buffer to reserve room on | |
372 | * @attrtype: attribute type | |
373 | * @attrlen: length of attribute payload | |
374 | * | |
375 | * Adds a netlink attribute header to a socket buffer and reserves | |
376 | * room for the payload but does not copy it. | |
377 | * | |
378 | * Returns NULL if the tailroom of the skb is insufficient to store | |
379 | * the attribute header and payload. | |
380 | */ | |
381 | struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen) | |
382 | { | |
383 | if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen))) | |
384 | return NULL; | |
385 | ||
386 | return __nla_reserve(skb, attrtype, attrlen); | |
387 | } | |
388 | EXPORT_SYMBOL(nla_reserve); | |
389 | ||
390 | /** | |
391 | * nla_reserve_nohdr - reserve room for attribute without header | |
392 | * @skb: socket buffer to reserve room on | |
393 | * @attrlen: length of attribute payload | |
394 | * | |
395 | * Reserves room for attribute payload without a header. | |
396 | * | |
397 | * Returns NULL if the tailroom of the skb is insufficient to store | |
398 | * the attribute payload. | |
399 | */ | |
400 | void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen) | |
401 | { | |
402 | if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen))) | |
403 | return NULL; | |
404 | ||
405 | return __nla_reserve_nohdr(skb, attrlen); | |
406 | } | |
407 | EXPORT_SYMBOL(nla_reserve_nohdr); | |
408 | ||
409 | /** | |
410 | * __nla_put - Add a netlink attribute to a socket buffer | |
411 | * @skb: socket buffer to add attribute to | |
412 | * @attrtype: attribute type | |
413 | * @attrlen: length of attribute payload | |
414 | * @data: head of attribute payload | |
415 | * | |
416 | * The caller is responsible to ensure that the skb provides enough | |
417 | * tailroom for the attribute header and payload. | |
418 | */ | |
419 | void __nla_put(struct sk_buff *skb, int attrtype, int attrlen, | |
420 | const void *data) | |
421 | { | |
422 | struct nlattr *nla; | |
423 | ||
424 | nla = __nla_reserve(skb, attrtype, attrlen); | |
425 | memcpy(nla_data(nla), data, attrlen); | |
426 | } | |
427 | EXPORT_SYMBOL(__nla_put); | |
428 | ||
429 | /** | |
430 | * __nla_put_nohdr - Add a netlink attribute without header | |
431 | * @skb: socket buffer to add attribute to | |
432 | * @attrlen: length of attribute payload | |
433 | * @data: head of attribute payload | |
434 | * | |
435 | * The caller is responsible to ensure that the skb provides enough | |
436 | * tailroom for the attribute payload. | |
437 | */ | |
438 | void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data) | |
439 | { | |
440 | void *start; | |
441 | ||
442 | start = __nla_reserve_nohdr(skb, attrlen); | |
443 | memcpy(start, data, attrlen); | |
444 | } | |
445 | EXPORT_SYMBOL(__nla_put_nohdr); | |
446 | ||
447 | /** | |
448 | * nla_put - Add a netlink attribute to a socket buffer | |
449 | * @skb: socket buffer to add attribute to | |
450 | * @attrtype: attribute type | |
451 | * @attrlen: length of attribute payload | |
452 | * @data: head of attribute payload | |
453 | * | |
454 | * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store | |
455 | * the attribute header and payload. | |
456 | */ | |
457 | int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data) | |
458 | { | |
459 | if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen))) | |
460 | return -EMSGSIZE; | |
461 | ||
462 | __nla_put(skb, attrtype, attrlen, data); | |
463 | return 0; | |
464 | } | |
465 | EXPORT_SYMBOL(nla_put); | |
466 | ||
467 | /** | |
468 | * nla_put_nohdr - Add a netlink attribute without header | |
469 | * @skb: socket buffer to add attribute to | |
470 | * @attrlen: length of attribute payload | |
471 | * @data: head of attribute payload | |
472 | * | |
473 | * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store | |
474 | * the attribute payload. | |
475 | */ | |
476 | int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data) | |
477 | { | |
478 | if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen))) | |
479 | return -EMSGSIZE; | |
480 | ||
481 | __nla_put_nohdr(skb, attrlen, data); | |
482 | return 0; | |
483 | } | |
484 | EXPORT_SYMBOL(nla_put_nohdr); | |
485 | ||
486 | /** | |
487 | * nla_append - Add a netlink attribute without header or padding | |
488 | * @skb: socket buffer to add attribute to | |
489 | * @attrlen: length of attribute payload | |
490 | * @data: head of attribute payload | |
491 | * | |
492 | * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store | |
493 | * the attribute payload. | |
494 | */ | |
495 | int nla_append(struct sk_buff *skb, int attrlen, const void *data) | |
496 | { | |
497 | if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen))) | |
498 | return -EMSGSIZE; | |
499 | ||
500 | memcpy(skb_put(skb, attrlen), data, attrlen); | |
501 | return 0; | |
502 | } | |
503 | EXPORT_SYMBOL(nla_append); | |
504 | #endif | |
505 | ||
506 | EXPORT_SYMBOL(nla_validate); | |
507 | EXPORT_SYMBOL(nla_policy_len); | |
508 | EXPORT_SYMBOL(nla_parse); | |
509 | EXPORT_SYMBOL(nla_find); | |
510 | EXPORT_SYMBOL(nla_strlcpy); | |
511 | EXPORT_SYMBOL(nla_memcpy); | |
512 | EXPORT_SYMBOL(nla_memcmp); | |
513 | EXPORT_SYMBOL(nla_strcmp); |