libnl  3.6.0
attr.c
1 /* SPDX-License-Identifier: LGPL-2.1-only */
2 /*
3  * Copyright (c) 2003-2013 Thomas Graf <tgraf@suug.ch>
4  */
5 
6 #include <netlink-private/netlink.h>
7 #include <netlink/netlink.h>
8 #include <netlink/utils.h>
9 #include <netlink/addr.h>
10 #include <netlink/attr.h>
11 #include <netlink/msg.h>
12 #include <linux/socket.h>
13 
14 /**
15  * @ingroup msg
16  * @defgroup attr Attributes
17  * Netlink Attributes Construction/Parsing Interface
18  *
19  * Related sections in the development guide:
20  * - @core_doc{core_attr,Netlink Attributes}
21  *
22  * @{
23  *
24  * Header
25  * ------
26  * ~~~~{.c}
27  * #include <netlink/attr.h>
28  * ~~~~
29  */
30 
31 /**
32  * @name Attribute Size Calculation
33  * @{
34  */
35 
36 /**
37  * Return size of attribute whithout padding.
38  * @arg payload Payload length of attribute.
39  *
40  * @code
41  * <-------- nla_attr_size(payload) --------->
42  * +------------------+- - -+- - - - - - - - - +- - -+
43  * | Attribute Header | Pad | Payload | Pad |
44  * +------------------+- - -+- - - - - - - - - +- - -+
45  * @endcode
46  *
47  * @return Size of attribute in bytes without padding.
48  */
49 int nla_attr_size(int payload)
50 {
51  return NLA_HDRLEN + payload;
52 }
53 
54 /**
55  * Return size of attribute including padding.
56  * @arg payload Payload length of attribute.
57  *
58  * @code
59  * <----------- nla_total_size(payload) ----------->
60  * +------------------+- - -+- - - - - - - - - +- - -+
61  * | Attribute Header | Pad | Payload | Pad |
62  * +------------------+- - -+- - - - - - - - - +- - -+
63  * @endcode
64  *
65  * @return Size of attribute in bytes.
66  */
67 int nla_total_size(int payload)
68 {
69  return NLA_ALIGN(nla_attr_size(payload));
70 }
71 
72 /**
73  * Return length of padding at the tail of the attribute.
74  * @arg payload Payload length of attribute.
75  *
76  * @code
77  * +------------------+- - -+- - - - - - - - - +- - -+
78  * | Attribute Header | Pad | Payload | Pad |
79  * +------------------+- - -+- - - - - - - - - +- - -+
80  * <--->
81  * @endcode
82  *
83  * @return Length of padding in bytes.
84  */
85 int nla_padlen(int payload)
86 {
87  return nla_total_size(payload) - nla_attr_size(payload);
88 }
89 
90 /** @} */
91 
92 /**
93  * @name Parsing Attributes
94  * @{
95  */
96 
97 /**
98  * Return type of the attribute.
99  * @arg nla Attribute.
100  *
101  * @return Type of attribute.
102  */
103 int nla_type(const struct nlattr *nla)
104 {
105  return nla->nla_type & NLA_TYPE_MASK;
106 }
107 
108 /**
109  * Return pointer to the payload section.
110  * @arg nla Attribute.
111  *
112  * @return Pointer to start of payload section.
113  */
114 void *nla_data(const struct nlattr *nla)
115 {
116  return (char *) nla + NLA_HDRLEN;
117 }
118 
119 /**
120  * Return length of the payload .
121  * @arg nla Attribute
122  *
123  * @return Length of payload in bytes.
124  */
125 int nla_len(const struct nlattr *nla)
126 {
127  return nla->nla_len - NLA_HDRLEN;
128 }
129 
130 /**
131  * Check if the attribute header and payload can be accessed safely.
132  * @arg nla Attribute of any kind.
133  * @arg remaining Number of bytes remaining in attribute stream.
134  *
135  * Verifies that the header and payload do not exceed the number of
136  * bytes left in the attribute stream. This function must be called
137  * before access the attribute header or payload when iterating over
138  * the attribute stream using nla_next().
139  *
140  * @return True if the attribute can be accessed safely, false otherwise.
141  */
142 int nla_ok(const struct nlattr *nla, int remaining)
143 {
144  return remaining >= (int) sizeof(*nla) &&
145  nla->nla_len >= sizeof(*nla) &&
146  nla->nla_len <= remaining;
147 }
148 
149 /**
150  * Return next attribute in a stream of attributes.
151  * @arg nla Attribute of any kind.
152  * @arg remaining Variable to count remaining bytes in stream.
153  *
154  * Calculates the offset to the next attribute based on the attribute
155  * given. The attribute provided is assumed to be accessible, the
156  * caller is responsible to use nla_ok() beforehand. The offset (length
157  * of specified attribute including padding) is then subtracted from
158  * the remaining bytes variable and a pointer to the next attribute is
159  * returned.
160  *
161  * nla_next() can be called as long as remainig is >0.
162  *
163  * @return Pointer to next attribute.
164  */
165 struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
166 {
167  int totlen = NLA_ALIGN(nla->nla_len);
168 
169  *remaining -= totlen;
170  return (struct nlattr *) ((char *) nla + totlen);
171 }
172 
173 static uint16_t nla_attr_minlen[NLA_TYPE_MAX+1] = {
174  [NLA_U8] = sizeof(uint8_t),
175  [NLA_U16] = sizeof(uint16_t),
176  [NLA_U32] = sizeof(uint32_t),
177  [NLA_U64] = sizeof(uint64_t),
178  [NLA_STRING] = 1,
179  [NLA_FLAG] = 0,
180 };
181 
182 static int validate_nla(const struct nlattr *nla, int maxtype,
183  const struct nla_policy *policy)
184 {
185  const struct nla_policy *pt;
186  unsigned int minlen = 0;
187  int type = nla_type(nla);
188 
189  if (type < 0 || type > maxtype)
190  return 0;
191 
192  pt = &policy[type];
193 
194  if (pt->type > NLA_TYPE_MAX)
195  BUG();
196 
197  if (pt->minlen)
198  minlen = pt->minlen;
199  else if (pt->type != NLA_UNSPEC)
200  minlen = nla_attr_minlen[pt->type];
201 
202  if (nla_len(nla) < minlen)
203  return -NLE_RANGE;
204 
205  if (pt->maxlen && nla_len(nla) > pt->maxlen)
206  return -NLE_RANGE;
207 
208  if (pt->type == NLA_STRING) {
209  const char *data = nla_data(nla);
210  if (data[nla_len(nla) - 1] != '\0')
211  return -NLE_INVAL;
212  }
213 
214  return 0;
215 }
216 
217 
218 /**
219  * Create attribute index based on a stream of attributes.
220  * @arg tb Index array to be filled (maxtype+1 elements).
221  * @arg maxtype Maximum attribute type expected and accepted.
222  * @arg head Head of attribute stream.
223  * @arg len Length of attribute stream.
224  * @arg policy Attribute validation policy.
225  *
226  * Iterates over the stream of attributes and stores a pointer to each
227  * attribute in the index array using the attribute type as index to
228  * the array. Attribute with a type greater than the maximum type
229  * specified will be silently ignored in order to maintain backwards
230  * compatibility. If \a policy is not NULL, the attribute will be
231  * validated using the specified policy.
232  *
233  * @see nla_validate
234  * @return 0 on success or a negative error code.
235  */
236 int nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head, int len,
237  const struct nla_policy *policy)
238 {
239  struct nlattr *nla;
240  int rem, err;
241 
242  memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
243 
244  nla_for_each_attr(nla, head, len, rem) {
245  int type = nla_type(nla);
246 
247  if (type > maxtype)
248  continue;
249 
250  if (policy) {
251  err = validate_nla(nla, maxtype, policy);
252  if (err < 0)
253  return err;
254  }
255 
256  if (tb[type])
257  NL_DBG(1, "Attribute of type %#x found multiple times in message, "
258  "previous attribute is being ignored.\n", type);
259 
260  tb[type] = nla;
261  }
262 
263  if (rem > 0) {
264  NL_DBG(1, "netlink: %d bytes leftover after parsing "
265  "attributes.\n", rem);
266  }
267 
268  return 0;
269 }
270 
271 /**
272  * Validate a stream of attributes.
273  * @arg head Head of attributes stream.
274  * @arg len Length of attributes stream.
275  * @arg maxtype Maximum attribute type expected and accepted.
276  * @arg policy Validation policy.
277  *
278  * Iterates over the stream of attributes and validates each attribute
279  * one by one using the specified policy. Attributes with a type greater
280  * than the maximum type specified will be silently ignored in order to
281  * maintain backwards compatibility.
282  *
283  * See section @core_doc{core_attr_parse,Attribute Parsing} for more details.
284  *
285  * @return 0 on success or a negative error code.
286  */
287 int nla_validate(const struct nlattr *head, int len, int maxtype,
288  const struct nla_policy *policy)
289 {
290  const struct nlattr *nla;
291  int rem, err;
292 
293  nla_for_each_attr(nla, head, len, rem) {
294  err = validate_nla(nla, maxtype, policy);
295  if (err < 0)
296  goto errout;
297  }
298 
299  err = 0;
300 errout:
301  return err;
302 }
303 
304 /**
305  * Find a single attribute in a stream of attributes.
306  * @arg head Head of attributes stream.
307  * @arg len Length of attributes stream.
308  * @arg attrtype Attribute type to look for.
309  *
310  * Iterates over the stream of attributes and compares each type with
311  * the type specified. Returns the first attribute which matches the
312  * type.
313  *
314  * @return Pointer to attribute found or NULL.
315  */
316 struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype)
317 {
318  const struct nlattr *nla;
319  int rem;
320 
321  nla_for_each_attr(nla, head, len, rem)
322  if (nla_type(nla) == attrtype)
323  return (struct nlattr*)nla;
324 
325  return NULL;
326 }
327 
328 /** @} */
329 
330 /**
331  * @name Helper Functions
332  * @{
333  */
334 
335 /**
336  * Copy attribute payload to another memory area.
337  * @arg dest Pointer to destination memory area.
338  * @arg src Attribute
339  * @arg count Number of bytes to copy at most.
340  *
341  * Note: The number of bytes copied is limited by the length of
342  * the attribute payload.
343  *
344  * @return The number of bytes copied to dest.
345  */
346 int nla_memcpy(void *dest, const struct nlattr *src, int count)
347 {
348  int minlen;
349 
350  if (!src)
351  return 0;
352 
353  minlen = min_t(int, count, nla_len(src));
354  memcpy(dest, nla_data(src), minlen);
355 
356  return minlen;
357 }
358 
359 /**
360  * Copy string attribute payload to a buffer.
361  * @arg dst Pointer to destination buffer.
362  * @arg nla Attribute of type NLA_STRING.
363  * @arg dstsize Size of destination buffer in bytes.
364  *
365  * Copies at most dstsize - 1 bytes to the destination buffer.
366  * The result is always a valid NUL terminated string. Unlike
367  * strlcpy the destination buffer is always padded out.
368  *
369  * @return The length of string attribute without the terminating NUL.
370  */
371 size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
372 {
373  size_t srclen = nla_len(nla);
374  const char *src = nla_data(nla);
375 
376  if (srclen > 0 && src[srclen - 1] == '\0')
377  srclen--;
378 
379  if (dstsize > 0) {
380  size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
381 
382  memset(dst, 0, dstsize);
383  memcpy(dst, src, len);
384  }
385 
386  return srclen;
387 }
388 
389 /**
390  * Compare attribute payload with memory area.
391  * @arg nla Attribute.
392  * @arg data Memory area to compare to.
393  * @arg size Number of bytes to compare.
394  *
395  * @see memcmp(3)
396  * @return An integer less than, equal to, or greater than zero.
397  */
398 int nla_memcmp(const struct nlattr *nla, const void *data, size_t size)
399 {
400  int d = nla_len(nla) - size;
401 
402  if (d == 0)
403  d = memcmp(nla_data(nla), data, size);
404 
405  return d;
406 }
407 
408 /**
409  * Compare string attribute payload with string
410  * @arg nla Attribute of type NLA_STRING.
411  * @arg str NUL terminated string.
412  *
413  * @see strcmp(3)
414  * @return An integer less than, equal to, or greater than zero.
415  */
416 int nla_strcmp(const struct nlattr *nla, const char *str)
417 {
418  int len = strlen(str) + 1;
419  int d = nla_len(nla) - len;
420 
421  if (d == 0)
422  d = memcmp(nla_data(nla), str, len);
423 
424  return d;
425 }
426 
427 /** @} */
428 
429 /**
430  * @name Unspecific Attribute
431  * @{
432  */
433 
434 /**
435  * Reserve space for a attribute.
436  * @arg msg Netlink Message.
437  * @arg attrtype Attribute Type.
438  * @arg attrlen Length of payload.
439  *
440  * Reserves room for a attribute in the specified netlink message and
441  * fills in the attribute header (type, length). Returns NULL if there
442  * is unsuficient space for the attribute.
443  *
444  * Any padding between payload and the start of the next attribute is
445  * zeroed out.
446  *
447  * @return Pointer to start of attribute or NULL on failure.
448  */
449 struct nlattr *nla_reserve(struct nl_msg *msg, int attrtype, int attrlen)
450 {
451  struct nlattr *nla;
452  int tlen;
453 
454  if (attrlen < 0)
455  return NULL;
456 
457  tlen = NLMSG_ALIGN(msg->nm_nlh->nlmsg_len) + nla_total_size(attrlen);
458 
459  if (tlen > msg->nm_size)
460  return NULL;
461 
462  nla = (struct nlattr *) nlmsg_tail(msg->nm_nlh);
463  nla->nla_type = attrtype;
464  nla->nla_len = nla_attr_size(attrlen);
465 
466  if (attrlen)
467  memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
468  msg->nm_nlh->nlmsg_len = tlen;
469 
470  NL_DBG(2, "msg %p: attr <%p> %d: Reserved %d (%d) bytes at offset +%td "
471  "nlmsg_len=%d\n", msg, nla, nla->nla_type,
472  nla_total_size(attrlen), attrlen,
473  (char *) nla - (char *) nlmsg_data(msg->nm_nlh),
474  msg->nm_nlh->nlmsg_len);
475 
476  return nla;
477 }
478 
479 /**
480  * Add a unspecific attribute to netlink message.
481  * @arg msg Netlink message.
482  * @arg attrtype Attribute type.
483  * @arg datalen Length of data to be used as payload.
484  * @arg data Pointer to data to be used as attribute payload.
485  *
486  * Reserves room for a unspecific attribute and copies the provided data
487  * into the message as payload of the attribute. Returns an error if there
488  * is insufficient space for the attribute.
489  *
490  * @see nla_reserve
491  * @return 0 on success or a negative error code.
492  */
493 int nla_put(struct nl_msg *msg, int attrtype, int datalen, const void *data)
494 {
495  struct nlattr *nla;
496 
497  nla = nla_reserve(msg, attrtype, datalen);
498  if (!nla) {
499  if (datalen < 0)
500  return -NLE_INVAL;
501 
502  return -NLE_NOMEM;
503  }
504 
505  if (datalen > 0) {
506  memcpy(nla_data(nla), data, datalen);
507  NL_DBG(2, "msg %p: attr <%p> %d: Wrote %d bytes at offset +%td\n",
508  msg, nla, nla->nla_type, datalen,
509  (char *) nla - (char *) nlmsg_data(msg->nm_nlh));
510  }
511 
512  return 0;
513 }
514 
515 /**
516  * Add abstract data as unspecific attribute to netlink message.
517  * @arg msg Netlink message.
518  * @arg attrtype Attribute type.
519  * @arg data Abstract data object.
520  *
521  * Equivalent to nla_put() except that the length of the payload is
522  * derived from the abstract data object.
523  *
524  * @see nla_put
525  * @return 0 on success or a negative error code.
526  */
527 int nla_put_data(struct nl_msg *msg, int attrtype, const struct nl_data *data)
528 {
529  return nla_put(msg, attrtype, nl_data_get_size(data),
530  nl_data_get(data));
531 }
532 
533 /**
534  * Add abstract address as unspecific attribute to netlink message.
535  * @arg msg Netlink message.
536  * @arg attrtype Attribute type.
537  * @arg addr Abstract address object.
538  *
539  * @see nla_put
540  * @return 0 on success or a negative error code.
541  */
542 int nla_put_addr(struct nl_msg *msg, int attrtype, struct nl_addr *addr)
543 {
544  return nla_put(msg, attrtype, nl_addr_get_len(addr),
546 }
547 
548 /** @} */
549 
550 /**
551  * @name Integer Attributes
552  */
553 
554 /**
555  * Add 8 bit signed integer attribute to netlink message.
556  * @arg msg Netlink message.
557  * @arg attrtype Attribute type.
558  * @arg value Numeric value to store as payload.
559  *
560  * @see nla_put
561  * @return 0 on success or a negative error code.
562  */
563 int nla_put_s8(struct nl_msg *msg, int attrtype, int8_t value)
564 {
565  return nla_put(msg, attrtype, sizeof(int8_t), &value);
566 }
567 
568 /**
569  * Return value of 8 bit signed integer attribute.
570  * @arg nla 8 bit integer attribute
571  *
572  * @return Payload as 8 bit integer.
573  */
574 int8_t nla_get_s8(const struct nlattr *nla)
575 {
576  return *(const int8_t *) nla_data(nla);
577 }
578 
579 /**
580  * Add 8 bit integer attribute to netlink message.
581  * @arg msg Netlink message.
582  * @arg attrtype Attribute type.
583  * @arg value Numeric value to store as payload.
584  *
585  * @see nla_put
586  * @return 0 on success or a negative error code.
587  */
588 int nla_put_u8(struct nl_msg *msg, int attrtype, uint8_t value)
589 {
590  return nla_put(msg, attrtype, sizeof(uint8_t), &value);
591 }
592 
593 /**
594  * Return value of 8 bit integer attribute.
595  * @arg nla 8 bit integer attribute
596  *
597  * @return Payload as 8 bit integer.
598  */
599 uint8_t nla_get_u8(const struct nlattr *nla)
600 {
601  return *(const uint8_t *) nla_data(nla);
602 }
603 
604 /**
605  * Add 16 bit signed integer attribute to netlink message.
606  * @arg msg Netlink message.
607  * @arg attrtype Attribute type.
608  * @arg value Numeric value to store as payload.
609  *
610  * @see nla_put
611  * @return 0 on success or a negative error code.
612  */
613 int nla_put_s16(struct nl_msg *msg, int attrtype, int16_t value)
614 {
615  return nla_put(msg, attrtype, sizeof(int16_t), &value);
616 }
617 
618 /**
619  * Return payload of 16 bit signed integer attribute.
620  * @arg nla 16 bit integer attribute
621  *
622  * @return Payload as 16 bit integer.
623  */
624 int16_t nla_get_s16(const struct nlattr *nla)
625 {
626  return *(const int16_t *) nla_data(nla);
627 }
628 
629 /**
630  * Add 16 bit integer attribute to netlink message.
631  * @arg msg Netlink message.
632  * @arg attrtype Attribute type.
633  * @arg value Numeric value to store as payload.
634  *
635  * @see nla_put
636  * @return 0 on success or a negative error code.
637  */
638 int nla_put_u16(struct nl_msg *msg, int attrtype, uint16_t value)
639 {
640  return nla_put(msg, attrtype, sizeof(uint16_t), &value);
641 }
642 
643 /**
644  * Return payload of 16 bit integer attribute.
645  * @arg nla 16 bit integer attribute
646  *
647  * @return Payload as 16 bit integer.
648  */
649 uint16_t nla_get_u16(const struct nlattr *nla)
650 {
651  return *(const uint16_t *) nla_data(nla);
652 }
653 
654 /**
655  * Add 32 bit signed integer attribute to netlink message.
656  * @arg msg Netlink message.
657  * @arg attrtype Attribute type.
658  * @arg value Numeric value to store as payload.
659  *
660  * @see nla_put
661  * @return 0 on success or a negative error code.
662  */
663 int nla_put_s32(struct nl_msg *msg, int attrtype, int32_t value)
664 {
665  return nla_put(msg, attrtype, sizeof(int32_t), &value);
666 }
667 
668 /**
669  * Return payload of 32 bit signed integer attribute.
670  * @arg nla 32 bit integer attribute.
671  *
672  * @return Payload as 32 bit integer.
673  */
674 int32_t nla_get_s32(const struct nlattr *nla)
675 {
676  return *(const int32_t *) nla_data(nla);
677 }
678 
679 /**
680  * Add 32 bit integer attribute to netlink message.
681  * @arg msg Netlink message.
682  * @arg attrtype Attribute type.
683  * @arg value Numeric value to store as payload.
684  *
685  * @see nla_put
686  * @return 0 on success or a negative error code.
687  */
688 int nla_put_u32(struct nl_msg *msg, int attrtype, uint32_t value)
689 {
690  return nla_put(msg, attrtype, sizeof(uint32_t), &value);
691 }
692 
693 /**
694  * Return payload of 32 bit integer attribute.
695  * @arg nla 32 bit integer attribute.
696  *
697  * @return Payload as 32 bit integer.
698  */
699 uint32_t nla_get_u32(const struct nlattr *nla)
700 {
701  return *(const uint32_t *) nla_data(nla);
702 }
703 
704 /**
705  * Add 64 bit signed integer attribute to netlink message.
706  * @arg msg Netlink message.
707  * @arg attrtype Attribute type.
708  * @arg value Numeric value to store as payload.
709  *
710  * @see nla_put
711  * @return 0 on success or a negative error code.
712  */
713 int nla_put_s64(struct nl_msg *msg, int attrtype, int64_t value)
714 {
715  return nla_put(msg, attrtype, sizeof(int64_t), &value);
716 }
717 
718 /**
719  * Return payload of s64 attribute
720  * @arg nla s64 netlink attribute
721  *
722  * @return Payload as 64 bit integer.
723  */
724 int64_t nla_get_s64(const struct nlattr *nla)
725 {
726  int64_t tmp = 0;
727 
728  if (nla && nla_len(nla) >= sizeof(tmp))
729  memcpy(&tmp, nla_data(nla), sizeof(tmp));
730 
731  return tmp;
732 }
733 
734 /**
735  * Add 64 bit integer attribute to netlink message.
736  * @arg msg Netlink message.
737  * @arg attrtype Attribute type.
738  * @arg value Numeric value to store as payload.
739  *
740  * @see nla_put
741  * @return 0 on success or a negative error code.
742  */
743 int nla_put_u64(struct nl_msg *msg, int attrtype, uint64_t value)
744 {
745  return nla_put(msg, attrtype, sizeof(uint64_t), &value);
746 }
747 
748 /**
749  * Return payload of u64 attribute
750  * @arg nla u64 netlink attribute
751  *
752  * @return Payload as 64 bit integer.
753  */
754 uint64_t nla_get_u64(const struct nlattr *nla)
755 {
756  uint64_t tmp = 0;
757 
758  if (nla && nla_len(nla) >= sizeof(tmp))
759  memcpy(&tmp, nla_data(nla), sizeof(tmp));
760 
761  return tmp;
762 }
763 
764 /** @} */
765 
766 /**
767  * @name String Attribute
768  */
769 
770 /**
771  * Add string attribute to netlink message.
772  * @arg msg Netlink message.
773  * @arg attrtype Attribute type.
774  * @arg str NUL terminated string.
775  *
776  * @see nla_put
777  * @return 0 on success or a negative error code.
778  */
779 int nla_put_string(struct nl_msg *msg, int attrtype, const char *str)
780 {
781  return nla_put(msg, attrtype, strlen(str) + 1, str);
782 }
783 
784 /**
785  * Return payload of string attribute.
786  * @arg nla String attribute.
787  *
788  * @return Pointer to attribute payload.
789  */
790 char *nla_get_string(const struct nlattr *nla)
791 {
792  return (char *) nla_data(nla);
793 }
794 
795 char *nla_strdup(const struct nlattr *nla)
796 {
797  return strdup(nla_get_string(nla));
798 }
799 
800 /** @} */
801 
802 /**
803  * @name Flag Attribute
804  */
805 
806 /**
807  * Add flag netlink attribute to netlink message.
808  * @arg msg Netlink message.
809  * @arg attrtype Attribute type.
810  *
811  * @see nla_put
812  * @return 0 on success or a negative error code.
813  */
814 int nla_put_flag(struct nl_msg *msg, int attrtype)
815 {
816  return nla_put(msg, attrtype, 0, NULL);
817 }
818 
819 /**
820  * Return true if flag attribute is set.
821  * @arg nla Flag netlink attribute.
822  *
823  * @return True if flag is set, otherwise false.
824  */
825 int nla_get_flag(const struct nlattr *nla)
826 {
827  return !!nla;
828 }
829 
830 /** @} */
831 
832 /**
833  * @name Microseconds Attribute
834  */
835 
836 /**
837  * Add a msecs netlink attribute to a netlink message
838  * @arg n netlink message
839  * @arg attrtype attribute type
840  * @arg msecs number of msecs
841  */
842 int nla_put_msecs(struct nl_msg *n, int attrtype, unsigned long msecs)
843 {
844  return nla_put_u64(n, attrtype, msecs);
845 }
846 
847 /**
848  * Return payload of msecs attribute
849  * @arg nla msecs netlink attribute
850  *
851  * @return the number of milliseconds.
852  */
853 unsigned long nla_get_msecs(const struct nlattr *nla)
854 {
855  return nla_get_u64(nla);
856 }
857 
858 /** @} */
859 
860 /**
861  * @name Nested Attribute
862  */
863 
864 /**
865  * Add nested attributes to netlink message.
866  * @arg msg Netlink message.
867  * @arg attrtype Attribute type.
868  * @arg nested Message containing attributes to be nested.
869  *
870  * Takes the attributes found in the \a nested message and appends them
871  * to the message \a msg nested in a container of the type \a attrtype.
872  * The \a nested message may not have a family specific header.
873  *
874  * @see nla_put
875  * @return 0 on success or a negative error code.
876  */
877 int nla_put_nested(struct nl_msg *msg, int attrtype,
878  const struct nl_msg *nested)
879 {
880  NL_DBG(2, "msg %p: attr <> %d: adding msg %p as nested attribute\n",
881  msg, attrtype, nested);
882 
883  return nla_put(msg, attrtype, nlmsg_datalen(nested->nm_nlh),
884  nlmsg_data(nested->nm_nlh));
885 }
886 
887 
888 /**
889  * Start a new level of nested attributes.
890  * @arg msg Netlink message.
891  * @arg attrtype Attribute type of container.
892  *
893  * @return Pointer to container attribute.
894  */
895 struct nlattr *nla_nest_start(struct nl_msg *msg, int attrtype)
896 {
897  struct nlattr *start = (struct nlattr *) nlmsg_tail(msg->nm_nlh);
898 
899  if (nla_put(msg, NLA_F_NESTED | attrtype, 0, NULL) < 0)
900  return NULL;
901 
902  NL_DBG(2, "msg %p: attr <%p> %d: starting nesting\n",
903  msg, start, start->nla_type);
904 
905  return start;
906 }
907 
908 static int _nest_end(struct nl_msg *msg, struct nlattr *start, int keep_empty)
909 {
910  size_t pad, len;
911 
912  len = (char *) nlmsg_tail(msg->nm_nlh) - (char *) start;
913 
914  if ( len > USHRT_MAX
915  || (!keep_empty && len == NLA_HDRLEN)) {
916  /*
917  * Max nlattr size exceeded or empty nested attribute, trim the
918  * attribute header again
919  */
920  nla_nest_cancel(msg, start);
921 
922  /* Return error only if nlattr size was exceeded */
923  return (len == NLA_HDRLEN) ? 0 : -NLE_ATTRSIZE;
924  }
925 
926  start->nla_len = len;
927 
928  pad = NLMSG_ALIGN(msg->nm_nlh->nlmsg_len) - msg->nm_nlh->nlmsg_len;
929  if (pad > 0) {
930  /*
931  * Data inside attribute does not end at a alignment boundry.
932  * Pad accordingly and accoun for the additional space in
933  * the message. nlmsg_reserve() may never fail in this situation,
934  * the allocate message buffer must be a multiple of NLMSG_ALIGNTO.
935  */
936  if (!nlmsg_reserve(msg, pad, 0))
937  BUG();
938 
939  NL_DBG(2, "msg %p: attr <%p> %d: added %zu bytes of padding\n",
940  msg, start, start->nla_type, pad);
941  }
942 
943  NL_DBG(2, "msg %p: attr <%p> %d: closing nesting, len=%u\n",
944  msg, start, start->nla_type, start->nla_len);
945 
946  return 0;
947 }
948 
949 /**
950  * Finalize nesting of attributes.
951  * @arg msg Netlink message.
952  * @arg start Container attribute as returned from nla_nest_start().
953  *
954  * Corrects the container attribute header to include the appeneded attributes.
955  *
956  * @return 0 on success or a negative error code.
957  */
958 int nla_nest_end(struct nl_msg *msg, struct nlattr *start)
959 {
960  return _nest_end (msg, start, 0);
961 }
962 
963 /**
964  * Finalize nesting of attributes without stripping off empty attributes.
965  * @arg msg Netlink message.
966  * @arg start Container attribute as returned from nla_nest_start().
967  *
968  * Corrects the container attribute header to include the appeneded attributes.
969  * Keep empty attribute if NO actual attribute payload exists.
970  *
971  * @return 0 on success or a negative error code.
972  */
973 int nla_nest_end_keep_empty(struct nl_msg *msg, struct nlattr *start)
974 {
975  return _nest_end (msg, start, 1);
976 }
977 
978 /**
979  * Cancel the addition of a nested attribute
980  * @arg msg Netlink message
981  * @arg attr Nested netlink attribute
982  *
983  * Removes any partially added nested Netlink attribute from the message
984  * by resetting the message to the size before the call to nla_nest_start()
985  * and by overwriting any potentially touched message segments with 0.
986  */
987 void nla_nest_cancel(struct nl_msg *msg, const struct nlattr *attr)
988 {
989  ssize_t len;
990 
991  len = (char *) nlmsg_tail(msg->nm_nlh) - (char *) attr;
992  if (len < 0)
993  BUG();
994  else if (len > 0) {
995  msg->nm_nlh->nlmsg_len -= len;
996  memset(nlmsg_tail(msg->nm_nlh), 0, len);
997  }
998 }
999 
1000 /**
1001  * Create attribute index based on nested attribute
1002  * @arg tb Index array to be filled (maxtype+1 elements).
1003  * @arg maxtype Maximum attribute type expected and accepted.
1004  * @arg nla Nested Attribute.
1005  * @arg policy Attribute validation policy.
1006  *
1007  * Feeds the stream of attributes nested into the specified attribute
1008  * to nla_parse().
1009  *
1010  * @see nla_parse
1011  * @return 0 on success or a negative error code.
1012  */
1013 int nla_parse_nested(struct nlattr *tb[], int maxtype, struct nlattr *nla,
1014  const struct nla_policy *policy)
1015 {
1016  return nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy);
1017 }
1018 
1019 /**
1020  * Return true if attribute has NLA_F_NESTED flag set
1021  * @arg attr Netlink attribute
1022  *
1023  * @return True if attribute has NLA_F_NESTED flag set, oterhwise False.
1024  */
1025 int nla_is_nested(const struct nlattr *attr)
1026 {
1027  return !!(attr->nla_type & NLA_F_NESTED);
1028 }
1029 
1030 /** @} */
1031 
1032 /** @} */
void * nl_addr_get_binary_addr(const struct nl_addr *addr)
Get binary address of abstract address object.
Definition: addr.c:935
unsigned int nl_addr_get_len(const struct nl_addr *addr)
Get length of binary address of abstract address object.
Definition: addr.c:947
int nla_validate(const struct nlattr *head, int len, int maxtype, const struct nla_policy *policy)
Validate a stream of attributes.
Definition: attr.c:287
int nla_put_s16(struct nl_msg *msg, int attrtype, int16_t value)
Add 16 bit signed integer attribute to netlink message.
Definition: attr.c:613
uint32_t nla_get_u32(const struct nlattr *nla)
Return payload of 32 bit integer attribute.
Definition: attr.c:699
int nla_put_u16(struct nl_msg *msg, int attrtype, uint16_t value)
Add 16 bit integer attribute to netlink message.
Definition: attr.c:638
uint16_t nla_get_u16(const struct nlattr *nla)
Return payload of 16 bit integer attribute.
Definition: attr.c:649
int nla_strcmp(const struct nlattr *nla, const char *str)
Compare string attribute payload with string.
Definition: attr.c:416
int nla_put_data(struct nl_msg *msg, int attrtype, const struct nl_data *data)
Add abstract data as unspecific attribute to netlink message.
Definition: attr.c:527
int nla_put_nested(struct nl_msg *msg, int attrtype, const struct nl_msg *nested)
Add nested attributes to netlink message.
Definition: attr.c:877
int nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head, int len, const struct nla_policy *policy)
Create attribute index based on a stream of attributes.
Definition: attr.c:236
int nla_put_string(struct nl_msg *msg, int attrtype, const char *str)
Add string attribute to netlink message.
Definition: attr.c:779
uint64_t nla_get_u64(const struct nlattr *nla)
Return payload of u64 attribute.
Definition: attr.c:754
int nla_get_flag(const struct nlattr *nla)
Return true if flag attribute is set.
Definition: attr.c:825
int nla_type(const struct nlattr *nla)
Return type of the attribute.
Definition: attr.c:103
int nla_put_u64(struct nl_msg *msg, int attrtype, uint64_t value)
Add 64 bit integer attribute to netlink message.
Definition: attr.c:743
struct nlattr * nla_find(const struct nlattr *head, int len, int attrtype)
Find a single attribute in a stream of attributes.
Definition: attr.c:316
int nla_ok(const struct nlattr *nla, int remaining)
Check if the attribute header and payload can be accessed safely.
Definition: attr.c:142
int nla_is_nested(const struct nlattr *attr)
Return true if attribute has NLA_F_NESTED flag set.
Definition: attr.c:1025
struct nlattr * nla_reserve(struct nl_msg *msg, int attrtype, int attrlen)
Reserve space for a attribute.
Definition: attr.c:449
int nla_put_u32(struct nl_msg *msg, int attrtype, uint32_t value)
Add 32 bit integer attribute to netlink message.
Definition: attr.c:688
struct nlattr * nla_next(const struct nlattr *nla, int *remaining)
Return next attribute in a stream of attributes.
Definition: attr.c:165
int nla_put_addr(struct nl_msg *msg, int attrtype, struct nl_addr *addr)
Add abstract address as unspecific attribute to netlink message.
Definition: attr.c:542
int nla_memcmp(const struct nlattr *nla, const void *data, size_t size)
Compare attribute payload with memory area.
Definition: attr.c:398
int nla_put_s64(struct nl_msg *msg, int attrtype, int64_t value)
Add 64 bit signed integer attribute to netlink message.
Definition: attr.c:713
#define nla_for_each_attr(pos, head, len, rem)
Iterate over a stream of attributes.
Definition: attr.h:312
int nla_put_msecs(struct nl_msg *n, int attrtype, unsigned long msecs)
Add a msecs netlink attribute to a netlink message.
Definition: attr.c:842
uint8_t nla_get_u8(const struct nlattr *nla)
Return value of 8 bit integer attribute.
Definition: attr.c:599
int nla_attr_size(int payload)
Return size of attribute whithout padding.
Definition: attr.c:49
int16_t nla_get_s16(const struct nlattr *nla)
Return payload of 16 bit signed integer attribute.
Definition: attr.c:624
int64_t nla_get_s64(const struct nlattr *nla)
Return payload of s64 attribute.
Definition: attr.c:724
int nla_put_flag(struct nl_msg *msg, int attrtype)
Add flag netlink attribute to netlink message.
Definition: attr.c:814
int nla_put_s32(struct nl_msg *msg, int attrtype, int32_t value)
Add 32 bit signed integer attribute to netlink message.
Definition: attr.c:663
int nla_memcpy(void *dest, const struct nlattr *src, int count)
Copy attribute payload to another memory area.
Definition: attr.c:346
struct nlattr * nla_nest_start(struct nl_msg *msg, int attrtype)
Start a new level of nested attributes.
Definition: attr.c:895
unsigned long nla_get_msecs(const struct nlattr *nla)
Return payload of msecs attribute.
Definition: attr.c:853
size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
Copy string attribute payload to a buffer.
Definition: attr.c:371
int nla_parse_nested(struct nlattr *tb[], int maxtype, struct nlattr *nla, const struct nla_policy *policy)
Create attribute index based on nested attribute.
Definition: attr.c:1013
int32_t nla_get_s32(const struct nlattr *nla)
Return payload of 32 bit signed integer attribute.
Definition: attr.c:674
void nla_nest_cancel(struct nl_msg *msg, const struct nlattr *attr)
Cancel the addition of a nested attribute.
Definition: attr.c:987
int nla_len(const struct nlattr *nla)
Return length of the payload .
Definition: attr.c:125
int nla_put_u8(struct nl_msg *msg, int attrtype, uint8_t value)
Add 8 bit integer attribute to netlink message.
Definition: attr.c:588
int nla_nest_end(struct nl_msg *msg, struct nlattr *start)
Finalize nesting of attributes.
Definition: attr.c:958
int nla_nest_end_keep_empty(struct nl_msg *msg, struct nlattr *start)
Finalize nesting of attributes without stripping off empty attributes.
Definition: attr.c:973
int8_t nla_get_s8(const struct nlattr *nla)
Return value of 8 bit signed integer attribute.
Definition: attr.c:574
int nla_padlen(int payload)
Return length of padding at the tail of the attribute.
Definition: attr.c:85
int nla_put(struct nl_msg *msg, int attrtype, int datalen, const void *data)
Add a unspecific attribute to netlink message.
Definition: attr.c:493
int nla_put_s8(struct nl_msg *msg, int attrtype, int8_t value)
Add 8 bit signed integer attribute to netlink message.
Definition: attr.c:563
void * nla_data(const struct nlattr *nla)
Return pointer to the payload section.
Definition: attr.c:114
char * nla_get_string(const struct nlattr *nla)
Return payload of string attribute.
Definition: attr.c:790
int nla_total_size(int payload)
Return size of attribute including padding.
Definition: attr.c:67
@ NLA_U64
64 bit integer
Definition: attr.h:38
@ NLA_STRING
NUL terminated character string.
Definition: attr.h:39
@ NLA_UNSPEC
Unspecified type, binary data chunk.
Definition: attr.h:34
@ NLA_U8
8 bit integer
Definition: attr.h:35
@ NLA_FLAG
Flag.
Definition: attr.h:40
@ NLA_U16
16 bit integer
Definition: attr.h:36
@ NLA_U32
32 bit integer
Definition: attr.h:37
void * nl_data_get(const struct nl_data *data)
Get data buffer of abstract data object.
Definition: data.c:148
size_t nl_data_get_size(const struct nl_data *data)
Get size of data buffer of abstract data object.
Definition: data.c:160
void * nlmsg_reserve(struct nl_msg *n, size_t len, int pad)
Reserve room for additional data in a netlink message.
Definition: msg.c:404
int nlmsg_datalen(const struct nlmsghdr *nlh)
Return length of message payload.
Definition: msg.c:116
void * nlmsg_data(const struct nlmsghdr *nlh)
Return pointer to message payload.
Definition: msg.c:100
Attribute validation policy.
Definition: attr.h:63
uint16_t maxlen
Maximal length of payload allowed.
Definition: attr.h:71
uint16_t minlen
Minimal length of payload required.
Definition: attr.h:68
uint16_t type
Type of attribute or NLA_UNSPEC.
Definition: attr.h:65