Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/lib/nlattr.c

  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 u8 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 

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