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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 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 | |
26 | static 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 | */ |
118 | int 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; |
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, struct nlattr *head, int len, |
177 | const struct nla_policy *policy) |
178 | { |
179 | 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] = 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(struct nlattr *head, int len, int attrtype) |
216 | { |
217 | struct nlattr *nla; |
218 | int rem; |
219 | |
220 | nla_for_each_attr(nla, head, len, rem) |
221 | if (nla_type(nla) == attrtype) |
222 | return 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); |
503 |
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