blob: fce1e9afc6d97a3a27787d44b48590a5850138aa
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/skbuff.h> |
13 | #include <linux/string.h> |
14 | #include <linux/types.h> |
15 | #include <net/netlink.h> |
16 | |
17 | static const u16 nla_attr_minlen[NLA_TYPE_MAX+1] = { |
18 | [NLA_U8] = sizeof(u8), |
19 | [NLA_U16] = sizeof(u16), |
20 | [NLA_U32] = sizeof(u32), |
21 | [NLA_U64] = sizeof(u64), |
22 | [NLA_MSECS] = sizeof(u64), |
23 | [NLA_NESTED] = NLA_HDRLEN, |
24 | [NLA_S8] = sizeof(s8), |
25 | [NLA_S16] = sizeof(s16), |
26 | [NLA_S32] = sizeof(s32), |
27 | [NLA_S64] = sizeof(s64), |
28 | }; |
29 | |
30 | static int validate_nla(const struct nlattr *nla, int maxtype, |
31 | const struct nla_policy *policy) |
32 | { |
33 | const struct nla_policy *pt; |
34 | int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla); |
35 | |
36 | if (type <= 0 || type > maxtype) |
37 | return 0; |
38 | |
39 | pt = &policy[type]; |
40 | |
41 | BUG_ON(pt->type > NLA_TYPE_MAX); |
42 | |
43 | switch (pt->type) { |
44 | case NLA_FLAG: |
45 | if (attrlen > 0) |
46 | return -ERANGE; |
47 | break; |
48 | |
49 | case NLA_NUL_STRING: |
50 | if (pt->len) |
51 | minlen = min_t(int, attrlen, pt->len + 1); |
52 | else |
53 | minlen = attrlen; |
54 | |
55 | if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL) |
56 | return -EINVAL; |
57 | /* fall through */ |
58 | |
59 | case NLA_STRING: |
60 | if (attrlen < 1) |
61 | return -ERANGE; |
62 | |
63 | if (pt->len) { |
64 | char *buf = nla_data(nla); |
65 | |
66 | if (buf[attrlen - 1] == '\0') |
67 | attrlen--; |
68 | |
69 | if (attrlen > pt->len) |
70 | return -ERANGE; |
71 | } |
72 | break; |
73 | |
74 | case NLA_BINARY: |
75 | if (pt->len && attrlen > pt->len) |
76 | return -ERANGE; |
77 | break; |
78 | |
79 | case NLA_NESTED_COMPAT: |
80 | if (attrlen < pt->len) |
81 | return -ERANGE; |
82 | if (attrlen < NLA_ALIGN(pt->len)) |
83 | break; |
84 | if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN) |
85 | return -ERANGE; |
86 | nla = nla_data(nla) + NLA_ALIGN(pt->len); |
87 | if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN + nla_len(nla)) |
88 | return -ERANGE; |
89 | break; |
90 | case NLA_NESTED: |
91 | /* a nested attributes is allowed to be empty; if its not, |
92 | * it must have a size of at least NLA_HDRLEN. |
93 | */ |
94 | if (attrlen == 0) |
95 | break; |
96 | default: |
97 | if (pt->len) |
98 | minlen = pt->len; |
99 | else if (pt->type != NLA_UNSPEC) |
100 | minlen = nla_attr_minlen[pt->type]; |
101 | |
102 | if (attrlen < minlen) |
103 | return -ERANGE; |
104 | } |
105 | |
106 | return 0; |
107 | } |
108 | |
109 | /** |
110 | * nla_validate - Validate a stream of attributes |
111 | * @head: head of attribute stream |
112 | * @len: length of attribute stream |
113 | * @maxtype: maximum attribute type to be expected |
114 | * @policy: validation policy |
115 | * |
116 | * Validates all attributes in the specified attribute stream against the |
117 | * specified policy. Attributes with a type exceeding maxtype will be |
118 | * ignored. See documenation of struct nla_policy for more details. |
119 | * |
120 | * Returns 0 on success or a negative error code. |
121 | */ |
122 | int nla_validate(const struct nlattr *head, int len, int maxtype, |
123 | const struct nla_policy *policy) |
124 | { |
125 | const struct nlattr *nla; |
126 | int rem, err; |
127 | |
128 | nla_for_each_attr(nla, head, len, rem) { |
129 | err = validate_nla(nla, maxtype, policy); |
130 | if (err < 0) |
131 | goto errout; |
132 | } |
133 | |
134 | err = 0; |
135 | errout: |
136 | return err; |
137 | } |
138 | EXPORT_SYMBOL(nla_validate); |
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 | EXPORT_SYMBOL(nla_policy_len); |
166 | |
167 | /** |
168 | * nla_parse - Parse a stream of attributes into a tb buffer |
169 | * @tb: destination array with maxtype+1 elements |
170 | * @maxtype: maximum attribute type to be expected |
171 | * @head: head of attribute stream |
172 | * @len: length of attribute stream |
173 | * @policy: validation policy |
174 | * |
175 | * Parses a stream of attributes and stores a pointer to each attribute in |
176 | * the tb array accessible via the attribute type. Attributes with a type |
177 | * exceeding maxtype will be silently ignored for backwards compatibility |
178 | * reasons. policy may be set to NULL if no validation is required. |
179 | * |
180 | * Returns 0 on success or a negative error code. |
181 | */ |
182 | int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head, |
183 | int len, const struct nla_policy *policy) |
184 | { |
185 | const struct nlattr *nla; |
186 | int rem, err; |
187 | |
188 | memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1)); |
189 | |
190 | nla_for_each_attr(nla, head, len, rem) { |
191 | u16 type = nla_type(nla); |
192 | |
193 | if (type > 0 && type <= maxtype) { |
194 | if (policy) { |
195 | err = validate_nla(nla, maxtype, policy); |
196 | if (err < 0) |
197 | goto errout; |
198 | } |
199 | |
200 | tb[type] = (struct nlattr *)nla; |
201 | } |
202 | } |
203 | |
204 | if (unlikely(rem > 0)) |
205 | pr_warn_ratelimited("netlink: %d bytes leftover after parsing attributes in process `%s'.\n", |
206 | rem, current->comm); |
207 | |
208 | err = 0; |
209 | errout: |
210 | return err; |
211 | } |
212 | EXPORT_SYMBOL(nla_parse); |
213 | |
214 | /** |
215 | * nla_find - Find a specific attribute in a stream of attributes |
216 | * @head: head of attribute stream |
217 | * @len: length of attribute stream |
218 | * @attrtype: type of attribute to look for |
219 | * |
220 | * Returns the first attribute in the stream matching the specified type. |
221 | */ |
222 | struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype) |
223 | { |
224 | const struct nlattr *nla; |
225 | int rem; |
226 | |
227 | nla_for_each_attr(nla, head, len, rem) |
228 | if (nla_type(nla) == attrtype) |
229 | return (struct nlattr *)nla; |
230 | |
231 | return NULL; |
232 | } |
233 | EXPORT_SYMBOL(nla_find); |
234 | |
235 | /** |
236 | * nla_strlcpy - Copy string attribute payload into a sized buffer |
237 | * @dst: where to copy the string to |
238 | * @nla: attribute to copy the string from |
239 | * @dstsize: size of destination buffer |
240 | * |
241 | * Copies at most dstsize - 1 bytes into the destination buffer. |
242 | * The result is always a valid NUL-terminated string. Unlike |
243 | * strlcpy the destination buffer is always padded out. |
244 | * |
245 | * Returns the length of the source buffer. |
246 | */ |
247 | size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize) |
248 | { |
249 | size_t srclen = nla_len(nla); |
250 | char *src = nla_data(nla); |
251 | |
252 | if (srclen > 0 && src[srclen - 1] == '\0') |
253 | srclen--; |
254 | |
255 | if (dstsize > 0) { |
256 | size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen; |
257 | |
258 | memset(dst, 0, dstsize); |
259 | memcpy(dst, src, len); |
260 | } |
261 | |
262 | return srclen; |
263 | } |
264 | EXPORT_SYMBOL(nla_strlcpy); |
265 | |
266 | /** |
267 | * nla_memcpy - Copy a netlink attribute into another memory area |
268 | * @dest: where to copy to memcpy |
269 | * @src: netlink attribute to copy from |
270 | * @count: size of the destination area |
271 | * |
272 | * Note: The number of bytes copied is limited by the length of |
273 | * attribute's payload. memcpy |
274 | * |
275 | * Returns the number of bytes copied. |
276 | */ |
277 | int nla_memcpy(void *dest, const struct nlattr *src, int count) |
278 | { |
279 | int minlen = min_t(int, count, nla_len(src)); |
280 | |
281 | memcpy(dest, nla_data(src), minlen); |
282 | if (count > minlen) |
283 | memset(dest + minlen, 0, count - minlen); |
284 | |
285 | return minlen; |
286 | } |
287 | EXPORT_SYMBOL(nla_memcpy); |
288 | |
289 | /** |
290 | * nla_memcmp - Compare an attribute with sized memory area |
291 | * @nla: netlink attribute |
292 | * @data: memory area |
293 | * @size: size of memory area |
294 | */ |
295 | int nla_memcmp(const struct nlattr *nla, const void *data, |
296 | size_t size) |
297 | { |
298 | int d = nla_len(nla) - size; |
299 | |
300 | if (d == 0) |
301 | d = memcmp(nla_data(nla), data, size); |
302 | |
303 | return d; |
304 | } |
305 | EXPORT_SYMBOL(nla_memcmp); |
306 | |
307 | /** |
308 | * nla_strcmp - Compare a string attribute against a string |
309 | * @nla: netlink string attribute |
310 | * @str: another string |
311 | */ |
312 | int nla_strcmp(const struct nlattr *nla, const char *str) |
313 | { |
314 | int len = strlen(str); |
315 | char *buf = nla_data(nla); |
316 | int attrlen = nla_len(nla); |
317 | int d; |
318 | |
319 | if (attrlen > 0 && buf[attrlen - 1] == '\0') |
320 | attrlen--; |
321 | |
322 | d = attrlen - len; |
323 | if (d == 0) |
324 | d = memcmp(nla_data(nla), str, len); |
325 | |
326 | return d; |
327 | } |
328 | EXPORT_SYMBOL(nla_strcmp); |
329 | |
330 | #ifdef CONFIG_NET |
331 | /** |
332 | * __nla_reserve - reserve room for attribute on the skb |
333 | * @skb: socket buffer to reserve room on |
334 | * @attrtype: attribute type |
335 | * @attrlen: length of attribute payload |
336 | * |
337 | * Adds a netlink attribute header to a socket buffer and reserves |
338 | * room for the payload but does not copy it. |
339 | * |
340 | * The caller is responsible to ensure that the skb provides enough |
341 | * tailroom for the attribute header and payload. |
342 | */ |
343 | struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen) |
344 | { |
345 | struct nlattr *nla; |
346 | |
347 | nla = (struct nlattr *) skb_put(skb, nla_total_size(attrlen)); |
348 | nla->nla_type = attrtype; |
349 | nla->nla_len = nla_attr_size(attrlen); |
350 | |
351 | memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen)); |
352 | |
353 | return nla; |
354 | } |
355 | EXPORT_SYMBOL(__nla_reserve); |
356 | |
357 | /** |
358 | * __nla_reserve_64bit - reserve room for attribute on the skb and align it |
359 | * @skb: socket buffer to reserve room on |
360 | * @attrtype: attribute type |
361 | * @attrlen: length of attribute payload |
362 | * @padattr: attribute type for the padding |
363 | * |
364 | * Adds a netlink attribute header to a socket buffer and reserves |
365 | * room for the payload but does not copy it. It also ensure that this |
366 | * attribute will have a 64-bit aligned nla_data() area. |
367 | * |
368 | * The caller is responsible to ensure that the skb provides enough |
369 | * tailroom for the attribute header and payload. |
370 | */ |
371 | struct nlattr *__nla_reserve_64bit(struct sk_buff *skb, int attrtype, |
372 | int attrlen, int padattr) |
373 | { |
374 | if (nla_need_padding_for_64bit(skb)) |
375 | nla_align_64bit(skb, padattr); |
376 | |
377 | return __nla_reserve(skb, attrtype, attrlen); |
378 | } |
379 | EXPORT_SYMBOL(__nla_reserve_64bit); |
380 | |
381 | /** |
382 | * __nla_reserve_nohdr - reserve room for attribute without header |
383 | * @skb: socket buffer to reserve room on |
384 | * @attrlen: length of attribute payload |
385 | * |
386 | * Reserves room for attribute payload without a header. |
387 | * |
388 | * The caller is responsible to ensure that the skb provides enough |
389 | * tailroom for the payload. |
390 | */ |
391 | void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen) |
392 | { |
393 | void *start; |
394 | |
395 | start = skb_put(skb, NLA_ALIGN(attrlen)); |
396 | memset(start, 0, NLA_ALIGN(attrlen)); |
397 | |
398 | return start; |
399 | } |
400 | EXPORT_SYMBOL(__nla_reserve_nohdr); |
401 | |
402 | /** |
403 | * nla_reserve - reserve room for attribute on the skb |
404 | * @skb: socket buffer to reserve room on |
405 | * @attrtype: attribute type |
406 | * @attrlen: length of attribute payload |
407 | * |
408 | * Adds a netlink attribute header to a socket buffer and reserves |
409 | * room for the payload but does not copy it. |
410 | * |
411 | * Returns NULL if the tailroom of the skb is insufficient to store |
412 | * the attribute header and payload. |
413 | */ |
414 | struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen) |
415 | { |
416 | if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen))) |
417 | return NULL; |
418 | |
419 | return __nla_reserve(skb, attrtype, attrlen); |
420 | } |
421 | EXPORT_SYMBOL(nla_reserve); |
422 | |
423 | /** |
424 | * nla_reserve_64bit - reserve room for attribute on the skb and align it |
425 | * @skb: socket buffer to reserve room on |
426 | * @attrtype: attribute type |
427 | * @attrlen: length of attribute payload |
428 | * @padattr: attribute type for the padding |
429 | * |
430 | * Adds a netlink attribute header to a socket buffer and reserves |
431 | * room for the payload but does not copy it. It also ensure that this |
432 | * attribute will have a 64-bit aligned nla_data() area. |
433 | * |
434 | * Returns NULL if the tailroom of the skb is insufficient to store |
435 | * the attribute header and payload. |
436 | */ |
437 | struct nlattr *nla_reserve_64bit(struct sk_buff *skb, int attrtype, int attrlen, |
438 | int padattr) |
439 | { |
440 | size_t len; |
441 | |
442 | if (nla_need_padding_for_64bit(skb)) |
443 | len = nla_total_size_64bit(attrlen); |
444 | else |
445 | len = nla_total_size(attrlen); |
446 | if (unlikely(skb_tailroom(skb) < len)) |
447 | return NULL; |
448 | |
449 | return __nla_reserve_64bit(skb, attrtype, attrlen, padattr); |
450 | } |
451 | EXPORT_SYMBOL(nla_reserve_64bit); |
452 | |
453 | /** |
454 | * nla_reserve_nohdr - reserve room for attribute without header |
455 | * @skb: socket buffer to reserve room on |
456 | * @attrlen: length of attribute payload |
457 | * |
458 | * Reserves room for attribute payload without a header. |
459 | * |
460 | * Returns NULL if the tailroom of the skb is insufficient to store |
461 | * the attribute payload. |
462 | */ |
463 | void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen) |
464 | { |
465 | if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen))) |
466 | return NULL; |
467 | |
468 | return __nla_reserve_nohdr(skb, attrlen); |
469 | } |
470 | EXPORT_SYMBOL(nla_reserve_nohdr); |
471 | |
472 | /** |
473 | * __nla_put - Add a netlink attribute to a socket buffer |
474 | * @skb: socket buffer to add attribute to |
475 | * @attrtype: attribute type |
476 | * @attrlen: length of attribute payload |
477 | * @data: head of attribute payload |
478 | * |
479 | * The caller is responsible to ensure that the skb provides enough |
480 | * tailroom for the attribute header and payload. |
481 | */ |
482 | void __nla_put(struct sk_buff *skb, int attrtype, int attrlen, |
483 | const void *data) |
484 | { |
485 | struct nlattr *nla; |
486 | |
487 | nla = __nla_reserve(skb, attrtype, attrlen); |
488 | memcpy(nla_data(nla), data, attrlen); |
489 | } |
490 | EXPORT_SYMBOL(__nla_put); |
491 | |
492 | /** |
493 | * __nla_put_64bit - Add a netlink attribute to a socket buffer and align it |
494 | * @skb: socket buffer to add attribute to |
495 | * @attrtype: attribute type |
496 | * @attrlen: length of attribute payload |
497 | * @data: head of attribute payload |
498 | * @padattr: attribute type for the padding |
499 | * |
500 | * The caller is responsible to ensure that the skb provides enough |
501 | * tailroom for the attribute header and payload. |
502 | */ |
503 | void __nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen, |
504 | const void *data, int padattr) |
505 | { |
506 | struct nlattr *nla; |
507 | |
508 | nla = __nla_reserve_64bit(skb, attrtype, attrlen, padattr); |
509 | memcpy(nla_data(nla), data, attrlen); |
510 | } |
511 | EXPORT_SYMBOL(__nla_put_64bit); |
512 | |
513 | /** |
514 | * __nla_put_nohdr - Add a netlink attribute without header |
515 | * @skb: socket buffer to add attribute to |
516 | * @attrlen: length of attribute payload |
517 | * @data: head of attribute payload |
518 | * |
519 | * The caller is responsible to ensure that the skb provides enough |
520 | * tailroom for the attribute payload. |
521 | */ |
522 | void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data) |
523 | { |
524 | void *start; |
525 | |
526 | start = __nla_reserve_nohdr(skb, attrlen); |
527 | memcpy(start, data, attrlen); |
528 | } |
529 | EXPORT_SYMBOL(__nla_put_nohdr); |
530 | |
531 | /** |
532 | * nla_put - Add a netlink attribute to a socket buffer |
533 | * @skb: socket buffer to add attribute to |
534 | * @attrtype: attribute type |
535 | * @attrlen: length of attribute payload |
536 | * @data: head of attribute payload |
537 | * |
538 | * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store |
539 | * the attribute header and payload. |
540 | */ |
541 | int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data) |
542 | { |
543 | if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen))) |
544 | return -EMSGSIZE; |
545 | |
546 | __nla_put(skb, attrtype, attrlen, data); |
547 | return 0; |
548 | } |
549 | EXPORT_SYMBOL(nla_put); |
550 | |
551 | /** |
552 | * nla_put_64bit - Add a netlink attribute to a socket buffer and align it |
553 | * @skb: socket buffer to add attribute to |
554 | * @attrtype: attribute type |
555 | * @attrlen: length of attribute payload |
556 | * @data: head of attribute payload |
557 | * @padattr: attribute type for the padding |
558 | * |
559 | * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store |
560 | * the attribute header and payload. |
561 | */ |
562 | int nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen, |
563 | const void *data, int padattr) |
564 | { |
565 | size_t len; |
566 | |
567 | if (nla_need_padding_for_64bit(skb)) |
568 | len = nla_total_size_64bit(attrlen); |
569 | else |
570 | len = nla_total_size(attrlen); |
571 | if (unlikely(skb_tailroom(skb) < len)) |
572 | return -EMSGSIZE; |
573 | |
574 | __nla_put_64bit(skb, attrtype, attrlen, data, padattr); |
575 | return 0; |
576 | } |
577 | EXPORT_SYMBOL(nla_put_64bit); |
578 | |
579 | /** |
580 | * nla_put_nohdr - Add a netlink attribute without header |
581 | * @skb: socket buffer to add attribute to |
582 | * @attrlen: length of attribute payload |
583 | * @data: head of attribute payload |
584 | * |
585 | * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store |
586 | * the attribute payload. |
587 | */ |
588 | int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data) |
589 | { |
590 | if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen))) |
591 | return -EMSGSIZE; |
592 | |
593 | __nla_put_nohdr(skb, attrlen, data); |
594 | return 0; |
595 | } |
596 | EXPORT_SYMBOL(nla_put_nohdr); |
597 | |
598 | /** |
599 | * nla_append - Add a netlink attribute without header or padding |
600 | * @skb: socket buffer to add attribute to |
601 | * @attrlen: length of attribute payload |
602 | * @data: head of attribute payload |
603 | * |
604 | * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store |
605 | * the attribute payload. |
606 | */ |
607 | int nla_append(struct sk_buff *skb, int attrlen, const void *data) |
608 | { |
609 | if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen))) |
610 | return -EMSGSIZE; |
611 | |
612 | memcpy(skb_put(skb, attrlen), data, attrlen); |
613 | return 0; |
614 | } |
615 | EXPORT_SYMBOL(nla_append); |
616 | #endif |
617 |