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
validate_nla(const struct nlattr * nla,int maxtype,const struct nla_policy * policy)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 */
nla_validate(const struct nlattr * head,int len,int maxtype,const struct nla_policy * policy)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 EXPORT_SYMBOL(nla_validate);
140
141 /**
142 * nla_policy_len - Determin the max. length of a policy
143 * @policy: policy to use
144 * @n: number of policies
145 *
146 * Determines the max. length of the policy. It is currently used
147 * to allocated Netlink buffers roughly the size of the actual
148 * message.
149 *
150 * Returns 0 on success or a negative error code.
151 */
152 int
nla_policy_len(const struct nla_policy * p,int n)153 nla_policy_len(const struct nla_policy *p, int n)
154 {
155 int i, len = 0;
156
157 for (i = 0; i < n; i++, p++) {
158 if (p->len)
159 len += nla_total_size(p->len);
160 else if (nla_attr_minlen[p->type])
161 len += nla_total_size(nla_attr_minlen[p->type]);
162 }
163
164 return len;
165 }
166 EXPORT_SYMBOL(nla_policy_len);
167
168 /**
169 * nla_parse - Parse a stream of attributes into a tb buffer
170 * @tb: destination array with maxtype+1 elements
171 * @maxtype: maximum attribute type to be expected
172 * @head: head of attribute stream
173 * @len: length of attribute stream
174 * @policy: validation policy
175 *
176 * Parses a stream of attributes and stores a pointer to each attribute in
177 * the tb array accessible via the attribute type. Attributes with a type
178 * exceeding maxtype will be silently ignored for backwards compatibility
179 * reasons. policy may be set to NULL if no validation is required.
180 *
181 * Returns 0 on success or a negative error code.
182 */
nla_parse(struct nlattr ** tb,int maxtype,const struct nlattr * head,int len,const struct nla_policy * policy)183 int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head,
184 int len, const struct nla_policy *policy)
185 {
186 const struct nlattr *nla;
187 int rem, err;
188
189 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
190
191 nla_for_each_attr(nla, head, len, rem) {
192 u16 type = nla_type(nla);
193
194 if (type > 0 && type <= maxtype) {
195 if (policy) {
196 err = validate_nla(nla, maxtype, policy);
197 if (err < 0)
198 goto errout;
199 }
200
201 tb[type] = (struct nlattr *)nla;
202 }
203 }
204
205 if (unlikely(rem > 0))
206 pr_warn_ratelimited("netlink: %d bytes leftover after parsing attributes in process `%s'.\n",
207 rem, current->comm);
208
209 err = 0;
210 errout:
211 return err;
212 }
213 EXPORT_SYMBOL(nla_parse);
214
215 /**
216 * nla_find - Find a specific attribute in a stream of attributes
217 * @head: head of attribute stream
218 * @len: length of attribute stream
219 * @attrtype: type of attribute to look for
220 *
221 * Returns the first attribute in the stream matching the specified type.
222 */
nla_find(const struct nlattr * head,int len,int attrtype)223 struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype)
224 {
225 const struct nlattr *nla;
226 int rem;
227
228 nla_for_each_attr(nla, head, len, rem)
229 if (nla_type(nla) == attrtype)
230 return (struct nlattr *)nla;
231
232 return NULL;
233 }
234 EXPORT_SYMBOL(nla_find);
235
236 /**
237 * nla_strlcpy - Copy string attribute payload into a sized buffer
238 * @dst: where to copy the string to
239 * @nla: attribute to copy the string from
240 * @dstsize: size of destination buffer
241 *
242 * Copies at most dstsize - 1 bytes into the destination buffer.
243 * The result is always a valid NUL-terminated string. Unlike
244 * strlcpy the destination buffer is always padded out.
245 *
246 * Returns the length of the source buffer.
247 */
nla_strlcpy(char * dst,const struct nlattr * nla,size_t dstsize)248 size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
249 {
250 size_t srclen = nla_len(nla);
251 char *src = nla_data(nla);
252
253 if (srclen > 0 && src[srclen - 1] == '\0')
254 srclen--;
255
256 if (dstsize > 0) {
257 size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
258
259 memset(dst, 0, dstsize);
260 memcpy(dst, src, len);
261 }
262
263 return srclen;
264 }
265 EXPORT_SYMBOL(nla_strlcpy);
266
267 /**
268 * nla_memcpy - Copy a netlink attribute into another memory area
269 * @dest: where to copy to memcpy
270 * @src: netlink attribute to copy from
271 * @count: size of the destination area
272 *
273 * Note: The number of bytes copied is limited by the length of
274 * attribute's payload. memcpy
275 *
276 * Returns the number of bytes copied.
277 */
nla_memcpy(void * dest,const struct nlattr * src,int count)278 int nla_memcpy(void *dest, const struct nlattr *src, int count)
279 {
280 int minlen = min_t(int, count, nla_len(src));
281
282 memcpy(dest, nla_data(src), minlen);
283
284 return minlen;
285 }
286 EXPORT_SYMBOL(nla_memcpy);
287
288 /**
289 * nla_memcmp - Compare an attribute with sized memory area
290 * @nla: netlink attribute
291 * @data: memory area
292 * @size: size of memory area
293 */
nla_memcmp(const struct nlattr * nla,const void * data,size_t size)294 int nla_memcmp(const struct nlattr *nla, const void *data,
295 size_t size)
296 {
297 int d = nla_len(nla) - size;
298
299 if (d == 0)
300 d = memcmp(nla_data(nla), data, size);
301
302 return d;
303 }
304 EXPORT_SYMBOL(nla_memcmp);
305
306 /**
307 * nla_strcmp - Compare a string attribute against a string
308 * @nla: netlink string attribute
309 * @str: another string
310 */
nla_strcmp(const struct nlattr * nla,const char * str)311 int nla_strcmp(const struct nlattr *nla, const char *str)
312 {
313 int len = strlen(str);
314 char *buf = nla_data(nla);
315 int attrlen = nla_len(nla);
316 int d;
317
318 if (attrlen > 0 && buf[attrlen - 1] == '\0')
319 attrlen--;
320
321 d = attrlen - len;
322 if (d == 0)
323 d = memcmp(nla_data(nla), str, len);
324
325 return d;
326 }
327 EXPORT_SYMBOL(nla_strcmp);
328
329 #ifdef CONFIG_NET
330 /**
331 * __nla_reserve - reserve room for attribute on the skb
332 * @skb: socket buffer to reserve room on
333 * @attrtype: attribute type
334 * @attrlen: length of attribute payload
335 *
336 * Adds a netlink attribute header to a socket buffer and reserves
337 * room for the payload but does not copy it.
338 *
339 * The caller is responsible to ensure that the skb provides enough
340 * tailroom for the attribute header and payload.
341 */
__nla_reserve(struct sk_buff * skb,int attrtype,int attrlen)342 struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
343 {
344 struct nlattr *nla;
345
346 nla = (struct nlattr *) skb_put(skb, nla_total_size(attrlen));
347 nla->nla_type = attrtype;
348 nla->nla_len = nla_attr_size(attrlen);
349
350 memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
351
352 return nla;
353 }
354 EXPORT_SYMBOL(__nla_reserve);
355
356 /**
357 * __nla_reserve_nohdr - reserve room for attribute without header
358 * @skb: socket buffer to reserve room on
359 * @attrlen: length of attribute payload
360 *
361 * Reserves room for attribute payload without a header.
362 *
363 * The caller is responsible to ensure that the skb provides enough
364 * tailroom for the payload.
365 */
__nla_reserve_nohdr(struct sk_buff * skb,int attrlen)366 void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
367 {
368 void *start;
369
370 start = skb_put(skb, NLA_ALIGN(attrlen));
371 memset(start, 0, NLA_ALIGN(attrlen));
372
373 return start;
374 }
375 EXPORT_SYMBOL(__nla_reserve_nohdr);
376
377 /**
378 * nla_reserve - reserve room for attribute on the skb
379 * @skb: socket buffer to reserve room on
380 * @attrtype: attribute type
381 * @attrlen: length of attribute payload
382 *
383 * Adds a netlink attribute header to a socket buffer and reserves
384 * room for the payload but does not copy it.
385 *
386 * Returns NULL if the tailroom of the skb is insufficient to store
387 * the attribute header and payload.
388 */
nla_reserve(struct sk_buff * skb,int attrtype,int attrlen)389 struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
390 {
391 if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
392 return NULL;
393
394 return __nla_reserve(skb, attrtype, attrlen);
395 }
396 EXPORT_SYMBOL(nla_reserve);
397
398 /**
399 * nla_reserve_nohdr - reserve room for attribute without header
400 * @skb: socket buffer to reserve room on
401 * @attrlen: length of attribute payload
402 *
403 * Reserves room for attribute payload without a header.
404 *
405 * Returns NULL if the tailroom of the skb is insufficient to store
406 * the attribute payload.
407 */
nla_reserve_nohdr(struct sk_buff * skb,int attrlen)408 void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
409 {
410 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
411 return NULL;
412
413 return __nla_reserve_nohdr(skb, attrlen);
414 }
415 EXPORT_SYMBOL(nla_reserve_nohdr);
416
417 /**
418 * __nla_put - Add a netlink attribute to a socket buffer
419 * @skb: socket buffer to add attribute to
420 * @attrtype: attribute type
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 header and payload.
426 */
__nla_put(struct sk_buff * skb,int attrtype,int attrlen,const void * data)427 void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
428 const void *data)
429 {
430 struct nlattr *nla;
431
432 nla = __nla_reserve(skb, attrtype, attrlen);
433 memcpy(nla_data(nla), data, attrlen);
434 }
435 EXPORT_SYMBOL(__nla_put);
436
437 /**
438 * __nla_put_nohdr - Add a netlink attribute without header
439 * @skb: socket buffer to add attribute to
440 * @attrlen: length of attribute payload
441 * @data: head of attribute payload
442 *
443 * The caller is responsible to ensure that the skb provides enough
444 * tailroom for the attribute payload.
445 */
__nla_put_nohdr(struct sk_buff * skb,int attrlen,const void * data)446 void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
447 {
448 void *start;
449
450 start = __nla_reserve_nohdr(skb, attrlen);
451 memcpy(start, data, attrlen);
452 }
453 EXPORT_SYMBOL(__nla_put_nohdr);
454
455 /**
456 * nla_put - Add a netlink attribute to a socket buffer
457 * @skb: socket buffer to add attribute to
458 * @attrtype: attribute type
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 header and payload.
464 */
nla_put(struct sk_buff * skb,int attrtype,int attrlen,const void * data)465 int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
466 {
467 if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
468 return -EMSGSIZE;
469
470 __nla_put(skb, attrtype, attrlen, data);
471 return 0;
472 }
473 EXPORT_SYMBOL(nla_put);
474
475 /**
476 * nla_put_nohdr - Add a netlink attribute without header
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 */
nla_put_nohdr(struct sk_buff * skb,int attrlen,const void * data)484 int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
485 {
486 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
487 return -EMSGSIZE;
488
489 __nla_put_nohdr(skb, attrlen, data);
490 return 0;
491 }
492 EXPORT_SYMBOL(nla_put_nohdr);
493
494 /**
495 * nla_append - Add a netlink attribute without header or padding
496 * @skb: socket buffer to add attribute to
497 * @attrlen: length of attribute payload
498 * @data: head of attribute payload
499 *
500 * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
501 * the attribute payload.
502 */
nla_append(struct sk_buff * skb,int attrlen,const void * data)503 int nla_append(struct sk_buff *skb, int attrlen, const void *data)
504 {
505 if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
506 return -EMSGSIZE;
507
508 memcpy(skb_put(skb, attrlen), data, attrlen);
509 return 0;
510 }
511 EXPORT_SYMBOL(nla_append);
512 #endif
513