aboutsummaryrefslogtreecommitdiffstats
path: root/include/net/netlink.h
blob: 0bf325c29aff4803a9dcfed9b53d12cce6ac3ae1 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
#ifndef __NET_NETLINK_H
#define __NET_NETLINK_H

#include <linux/types.h>
#include <linux/netlink.h>
#include <linux/jiffies.h>

/* ========================================================================
 *         Netlink Messages and Attributes Interface (As Seen On TV)
 * ------------------------------------------------------------------------
 *                          Messages Interface
 * ------------------------------------------------------------------------
 *
 * Message Format:
 *    <--- nlmsg_total_size(payload)  --->
 *    <-- nlmsg_msg_size(payload) ->
 *   +----------+- - -+-------------+- - -+-------- - -
 *   | nlmsghdr | Pad |   Payload   | Pad | nlmsghdr
 *   +----------+- - -+-------------+- - -+-------- - -
 *   nlmsg_data(nlh)---^                   ^
 *   nlmsg_next(nlh)-----------------------+
 *
 * Payload Format:
 *    <---------------------- nlmsg_len(nlh) --------------------->
 *    <------ hdrlen ------>       <- nlmsg_attrlen(nlh, hdrlen) ->
 *   +----------------------+- - -+--------------------------------+
 *   |     Family Header    | Pad |           Attributes           |
 *   +----------------------+- - -+--------------------------------+
 *   nlmsg_attrdata(nlh, hdrlen)---^
 *
 * Data Structures:
 *   struct nlmsghdr			netlink message header
 *
 * Message Construction:
 *   nlmsg_new()			create a new netlink message
 *   nlmsg_put()			add a netlink message to an skb
 *   nlmsg_put_answer()			callback based nlmsg_put()
 *   nlmsg_end()			finanlize netlink message
 *   nlmsg_get_pos()			return current position in message
 *   nlmsg_trim()			trim part of message
 *   nlmsg_cancel()			cancel message construction
 *   nlmsg_free()			free a netlink message
 *
 * Message Sending:
 *   nlmsg_multicast()			multicast message to several groups
 *   nlmsg_unicast()			unicast a message to a single socket
 *   nlmsg_notify()			send notification message
 *
 * Message Length Calculations:
 *   nlmsg_msg_size(payload)		length of message w/o padding
 *   nlmsg_total_size(payload)		length of message w/ padding
 *   nlmsg_padlen(payload)		length of padding at tail
 *
 * Message Payload Access:
 *   nlmsg_data(nlh)			head of message payload
 *   nlmsg_len(nlh)			length of message payload
 *   nlmsg_attrdata(nlh, hdrlen)	head of attributes data
 *   nlmsg_attrlen(nlh, hdrlen)		length of attributes data
 *
 * Message Parsing:
 *   nlmsg_ok(nlh, remaining)		does nlh fit into remaining bytes?
 *   nlmsg_next(nlh, remaining)		get next netlink message
 *   nlmsg_parse()			parse attributes of a message
 *   nlmsg_find_attr()			find an attribute in a message
 *   nlmsg_for_each_msg()		loop over all messages
 *   nlmsg_validate()			validate netlink message incl. attrs
 *   nlmsg_for_each_attr()		loop over all attributes
 *
 * Misc:
 *   nlmsg_report()			report back to application?
 *
 * ------------------------------------------------------------------------
 *                          Attributes Interface
 * ------------------------------------------------------------------------
 *
 * Attribute Format:
 *    <------- nla_total_size(payload) ------->
 *    <---- nla_attr_size(payload) ----->
 *   +----------+- - -+- - - - - - - - - +- - -+-------- - -
 *   |  Header  | Pad |     Payload      | Pad |  Header
 *   +----------+- - -+- - - - - - - - - +- - -+-------- - -
 *                     <- nla_len(nla) ->      ^
 *   nla_data(nla)----^                        |
 *   nla_next(nla)-----------------------------'
 *
 * Data Structures:
 *   struct nlattr			netlink attribtue header
 *
 * Attribute Construction:
 *   nla_reserve(skb, type, len)	reserve room for an attribute
 *   nla_reserve_nohdr(skb, len)	reserve room for an attribute w/o hdr
 *   nla_put(skb, type, len, data)	add attribute to skb
 *   nla_put_nohdr(skb, len, data)	add attribute w/o hdr
 *
 * Attribute Construction for Basic Types:
 *   nla_put_u8(skb, type, value)	add u8 attribute to skb
 *   nla_put_u16(skb, type, value)	add u16 attribute to skb
 *   nla_put_u32(skb, type, value)	add u32 attribute to skb
 *   nla_put_u64(skb, type, value)	add u64 attribute to skb
 *   nla_put_string(skb, type, str)	add string attribute to skb
 *   nla_put_flag(skb, type)		add flag attribute to skb
 *   nla_put_msecs(skb, type, jiffies)	add msecs attribute to skb
 *
 * Exceptions Based Attribute Construction:
 *   NLA_PUT(skb, type, len, data)	add attribute to skb
 *   NLA_PUT_U8(skb, type, value)	add u8 attribute to skb
 *   NLA_PUT_U16(skb, type, value)	add u16 attribute to skb
 *   NLA_PUT_U32(skb, type, value)	add u32 attribute to skb
 *   NLA_PUT_U64(skb, type, value)	add u64 attribute to skb
 *   NLA_PUT_STRING(skb, type, str)	add string attribute to skb
 *   NLA_PUT_FLAG(skb, type)		add flag attribute to skb
 *   NLA_PUT_MSECS(skb, type, jiffies)	add msecs attribute to skb
 *
 *   The meaning of these functions is equal to their lower case
 *   variants but they jump to the label nla_put_failure in case
 *   of a failure.
 *
 * Nested Attributes Construction:
 *   nla_nest_start(skb, type)		start a nested attribute
 *   nla_nest_end(skb, nla)		finalize a nested attribute
 *   nla_nest_cancel(skb, nla)		cancel nested attribute construction
 *
 * Attribute Length Calculations:
 *   nla_attr_size(payload)		length of attribute w/o padding
 *   nla_total_size(payload)		length of attribute w/ padding
 *   nla_padlen(payload)		length of padding
 *
 * Attribute Payload Access:
 *   nla_data(nla)			head of attribute payload
 *   nla_len(nla)			length of attribute payload
 *
 * Attribute Payload Access for Basic Types:
 *   nla_get_u8(nla)			get payload for a u8 attribute
 *   nla_get_u16(nla)			get payload for a u16 attribute
 *   nla_get_u32(nla)			get payload for a u32 attribute
 *   nla_get_u64(nla)			get payload for a u64 attribute
 *   nla_get_flag(nla)			return 1 if flag is true
 *   nla_get_msecs(nla)			get payload for a msecs attribute
 *
 * Attribute Misc:
 *   nla_memcpy(dest, nla, count)	copy attribute into memory
 *   nla_memcmp(nla, data, size)	compare attribute with memory area
 *   nla_strlcpy(dst, nla, size)	copy attribute to a sized string
 *   nla_strcmp(nla, str)		compare attribute with string
 *
 * Attribute Parsing:
 *   nla_ok(nla, remaining)		does nla fit into remaining bytes?
 *   nla_next(nla, remaining)		get next netlink attribute
 *   nla_validate()			validate a stream of attributes
 *   nla_validate_nested()		validate a stream of nested attributes
 *   nla_find()				find attribute in stream of attributes
 *   nla_find_nested()			find attribute in nested attributes
 *   nla_parse()			parse and validate stream of attrs
 *   nla_parse_nested()			parse nested attribuets
 *   nla_for_each_attr()		loop over all attributes
 *   nla_for_each_nested()		loop over the nested attributes
 *=========================================================================
 */

 /**
  * Standard attribute types to specify validation policy
  */
enum {
	NLA_UNSPEC,
	NLA_U8,
	NLA_U16,
	NLA_U32,
	NLA_U64,
	NLA_STRING,
	NLA_FLAG,
	NLA_MSECS,
	NLA_NESTED,
	NLA_NUL_STRING,
	NLA_BINARY,
	__NLA_TYPE_MAX,
};

#define NLA_TYPE_MAX (__NLA_TYPE_MAX - 1)

/**
 * struct nla_policy - attribute validation policy
 * @type: Type of attribute or NLA_UNSPEC
 * @len: Type specific length of payload
 *
 * Policies are defined as arrays of this struct, the array must be
 * accessible by attribute type up to the highest identifier to be expected.
 *
 * Meaning of `len' field:
 *    NLA_STRING           Maximum length of string
 *    NLA_NUL_STRING       Maximum length of string (excluding NUL)
 *    NLA_FLAG             Unused
 *    NLA_BINARY           Maximum length of attribute payload
 *    All other            Exact length of attribute payload
 *
 * Example:
 * static struct nla_policy my_policy[ATTR_MAX+1] __read_mostly = {
 * 	[ATTR_FOO] = { .type = NLA_U16 },
 *	[ATTR_BAR] = { .type = NLA_STRING, .len = BARSIZ },
 *	[ATTR_BAZ] = { .len = sizeof(struct mystruct) },
 * };
 */
struct nla_policy {
	u16		type;
	u16		len;
};

/**
 * struct nl_info - netlink source information
 * @nlh: Netlink message header of original request
 * @pid: Netlink PID of requesting application
 */
struct nl_info {
	struct nlmsghdr		*nlh;
	u32			pid;
};

extern void		netlink_run_queue(struct sock *sk, unsigned int *qlen,
					  int (*cb)(struct sk_buff *,
						    struct nlmsghdr *));
extern int		nlmsg_notify(struct sock *sk, struct sk_buff *skb,
				     u32 pid, unsigned int group, int report,
				     gfp_t flags);

extern int		nla_validate(struct nlattr *head, int len, int maxtype,
				     struct nla_policy *policy);
extern int		nla_parse(struct nlattr *tb[], int maxtype,
				  struct nlattr *head, int len,
				  struct nla_policy *policy);
extern struct nlattr *	nla_find(struct nlattr *head, int len, int attrtype);
extern size_t		nla_strlcpy(char *dst, const struct nlattr *nla,
				    size_t dstsize);
extern int		nla_memcpy(void *dest, struct nlattr *src, int count);
extern int		nla_memcmp(const struct nlattr *nla, const void *data,
				   size_t size);
extern int		nla_strcmp(const struct nlattr *nla, const char *str);
extern struct nlattr *	__nla_reserve(struct sk_buff *skb, int attrtype,
				      int attrlen);
extern void *		__nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
extern struct nlattr *	nla_reserve(struct sk_buff *skb, int attrtype,
				    int attrlen);
extern void *		nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
extern void		__nla_put(struct sk_buff *skb, int attrtype,
				  int attrlen, const void *data);
extern void		__nla_put_nohdr(struct sk_buff *skb, int attrlen,
					const void *data);
extern int		nla_put(struct sk_buff *skb, int attrtype,
				int attrlen, const void *data);
extern int		nla_put_nohdr(struct sk_buff *skb, int attrlen,
				      const void *data);

/**************************************************************************
 * Netlink Messages
 **************************************************************************/

/**
 * nlmsg_msg_size - length of netlink message not including padding
 * @payload: length of message payload
 */
static inline int nlmsg_msg_size(int payload)
{
	return NLMSG_HDRLEN + payload;
}

/**
 * nlmsg_total_size - length of netlink message including padding
 * @payload: length of message payload
 */
static inline int nlmsg_total_size(int payload)
{
	return NLMSG_ALIGN(nlmsg_msg_size(payload));
}

/**
 * nlmsg_padlen - length of padding at the message's tail
 * @payload: length of message payload
 */
static inline int nlmsg_padlen(int payload)
{
	return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
}

/**
 * nlmsg_data - head of message payload
 * @nlh: netlink messsage header
 */
static inline void *nlmsg_data(const struct nlmsghdr *nlh)
{
	return (unsigned char *) nlh + NLMSG_HDRLEN;
}

/**
 * nlmsg_len - length of message payload
 * @nlh: netlink message header
 */
static inline int nlmsg_len(const struct nlmsghdr *nlh)
{
	return nlh->nlmsg_len - NLMSG_HDRLEN;
}

/**
 * nlmsg_attrdata - head of attributes data
 * @nlh: netlink message header
 * @hdrlen: length of family specific header
 */
static inline struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh,
					    int hdrlen)
{
	unsigned char *data = nlmsg_data(nlh);
	return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
}

/**
 * nlmsg_attrlen - length of attributes data
 * @nlh: netlink message header
 * @hdrlen: length of family specific header
 */
static inline int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
{
	return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);
}

/**
 * nlmsg_ok - check if the netlink message fits into the remaining bytes
 * @nlh: netlink message header
 * @remaining: number of bytes remaining in message stream
 */
static inline int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
{
	return (remaining >= sizeof(struct nlmsghdr) &&
		nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
		nlh->nlmsg_len <= remaining);
}

/**
 * nlmsg_next - next netlink message in message stream
 * @nlh: netlink message header
 * @remaining: number of bytes remaining in message stream
 *
 * Returns the next netlink message in the message stream and
 * decrements remaining by the size of the current message.
 */
static inline struct nlmsghdr *nlmsg_next(struct nlmsghdr *nlh, int *remaining)
{
	int totlen = NLMSG_ALIGN(nlh->nlmsg_len);

	*remaining -= totlen;

	return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
}

/**
 * nlmsg_parse - parse attributes of a netlink message
 * @nlh: netlink message header
 * @hdrlen: length of family specific header
 * @tb: destination array with maxtype+1 elements
 * @maxtype: maximum attribute type to be expected
 * @policy: validation policy
 *
 * See nla_parse()
 */
static inline int nlmsg_parse(struct nlmsghdr *nlh, int hdrlen,
			      struct nlattr *tb[], int maxtype,
			      struct nla_policy *policy)
{
	if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
		return -EINVAL;

	return nla_parse(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
			 nlmsg_attrlen(nlh, hdrlen), policy);
}

/**
 * nlmsg_find_attr - find a specific attribute in a netlink message
 * @nlh: netlink message header
 * @hdrlen: length of familiy specific header
 * @attrtype: type of attribute to look for
 *
 * Returns the first attribute which matches the specified type.
 */
static inline struct nlattr *nlmsg_find_attr(struct nlmsghdr *nlh,
					     int hdrlen, int attrtype)
{
	return nla_find(nlmsg_attrdata(nlh, hdrlen),
			nlmsg_attrlen(nlh, hdrlen), attrtype);
}

/**
 * nlmsg_validate - validate a netlink message including attributes
 * @nlh: netlinket message header
 * @hdrlen: length of familiy specific header
 * @maxtype: maximum attribute type to be expected
 * @policy: validation policy
 */
static inline int nlmsg_validate(struct nlmsghdr *nlh, int hdrlen, int maxtype,
				 struct nla_policy *policy)
{
	if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
		return -EINVAL;

	return nla_validate(nlmsg_attrdata(nlh, hdrlen),
			    nlmsg_attrlen(nlh, hdrlen), maxtype, policy);
}

/**
 * nlmsg_report - need to report back to application?
 * @nlh: netlink message header
 *
 * Returns 1 if a report back to the application is requested.
 */
static inline int nlmsg_report(struct nlmsghdr *nlh)
{
	return !!(nlh->nlmsg_flags & NLM_F_ECHO);
}

/**
 * nlmsg_for_each_attr - iterate over a stream of attributes
 * @pos: loop counter, set to current attribute
 * @nlh: netlink message header
 * @hdrlen: length of familiy specific header
 * @rem: initialized to len, holds bytes currently remaining in stream
 */
#define nlmsg_for_each_attr(pos, nlh, hdrlen, rem) \
	nla_for_each_attr(pos, nlmsg_attrdata(nlh, hdrlen), \
			  nlmsg_attrlen(nlh, hdrlen), rem)

#if 0
/* FIXME: Enable once all users have been converted */

/**
 * __nlmsg_put - Add a new netlink message to an skb
 * @skb: socket buffer to store message in
 * @pid: netlink process id
 * @seq: sequence number of message
 * @type: message type
 * @payload: length of message payload
 * @flags: message flags
 *
 * The caller is responsible to ensure that the skb provides enough
 * tailroom for both the netlink header and payload.
 */
static inline struct nlmsghdr *__nlmsg_put(struct sk_buff *skb, u32 pid,
					   u32 seq, int type, int payload,
					   int flags)
{
	struct nlmsghdr *nlh;

	nlh = (struct nlmsghdr *) skb_put(skb, nlmsg_total_size(payload));
	nlh->nlmsg_type = type;
	nlh->nlmsg_len = nlmsg_msg_size(payload);
	nlh->nlmsg_flags = flags;
	nlh->nlmsg_pid = pid;
	nlh->nlmsg_seq = seq;

	memset((unsigned char *) nlmsg_data(nlh) + payload, 0,
	       nlmsg_padlen(payload));

	return nlh;
}
#endif

/**
 * nlmsg_put - Add a new netlink message to an skb
 * @skb: socket buffer to store message in
 * @pid: netlink process id
 * @seq: sequence number of message
 * @type: message type
 * @payload: length of message payload
 * @flags: message flags
 *
 * Returns NULL if the tailroom of the skb is insufficient to store
 * the message header and payload.
 */
static inline struct nlmsghdr *nlmsg_put(struct sk_buff *skb, u32 pid, u32 seq,
					 int type, int payload, int flags)
{
	if (unlikely(skb_tailroom(skb) < nlmsg_total_size(payload)))
		return NULL;

	return __nlmsg_put(skb, pid, seq, type, payload, flags);
}

/**
 * nlmsg_put_answer - Add a new callback based netlink message to an skb
 * @skb: socket buffer to store message in
 * @cb: netlink callback
 * @type: message type
 * @payload: length of message payload
 * @flags: message flags
 *
 * Returns NULL if the tailroom of the skb is insufficient to store
 * the message header and payload.
 */
static inline struct nlmsghdr *nlmsg_put_answer(struct sk_buff *skb,
						struct netlink_callback *cb,
						int type, int payload,
						int flags)
{
	return nlmsg_put(skb, NETLINK_CB(cb->skb).pid, cb->nlh->nlmsg_seq,
			 type, payload, flags);
}

/**
 * nlmsg_new - Allocate a new netlink message
 * @payload: size of the message payload
 * @flags: the type of memory to allocate.
 *
 * Use NLMSG_DEFAULT_SIZE if the size of the payload isn't known
 * and a good default is needed.
 */
static inline struct sk_buff *nlmsg_new(size_t payload, gfp_t flags)
{
	return alloc_skb(nlmsg_total_size(payload), flags);
}

/**
 * nlmsg_end - Finalize a netlink message
 * @skb: socket buffer the message is stored in
 * @nlh: netlink message header
 *
 * Corrects the netlink message header to include the appeneded
 * attributes. Only necessary if attributes have been added to
 * the message.
 *
 * Returns the total data length of the skb.
 */
static inline int nlmsg_end(struct sk_buff *skb, struct nlmsghdr *nlh)
{
	nlh->nlmsg_len = skb_tail_pointer(skb) - (unsigned char *)nlh;

	return skb->len;
}

/**
 * nlmsg_get_pos - return current position in netlink message
 * @skb: socket buffer the message is stored in
 *
 * Returns a pointer to the current tail of the message.
 */
static inline void *nlmsg_get_pos(struct sk_buff *skb)
{
	return skb_tail_pointer(skb);
}

/**
 * nlmsg_trim - Trim message to a mark
 * @skb: socket buffer the message is stored in
 * @mark: mark to trim to
 *
 * Trims the message to the provided mark. Returns -1.
 */
static inline int nlmsg_trim(struct sk_buff *skb, const void *mark)
{
	if (mark)
		skb_trim(skb, (unsigned char *) mark - skb->data);

	return -1;
}

/**
 * nlmsg_cancel - Cancel construction of a netlink message
 * @skb: socket buffer the message is stored in
 * @nlh: netlink message header
 *
 * Removes the complete netlink message including all
 * attributes from the socket buffer again. Returns -1.
 */
static inline int nlmsg_cancel(struct sk_buff *skb, struct nlmsghdr *nlh)
{
	return nlmsg_trim(skb, nlh);
}

/**
 * nlmsg_free - free a netlink message
 * @skb: socket buffer of netlink message
 */
static inline void nlmsg_free(struct sk_buff *skb)
{
	kfree_skb(skb);
}

/**
 * nlmsg_multicast - multicast a netlink message
 * @sk: netlink socket to spread messages to
 * @skb: netlink message as socket buffer
 * @pid: own netlink pid to avoid sending to yourself
 * @group: multicast group id
 * @flags: allocation flags
 */
static inline int nlmsg_multicast(struct sock *sk, struct sk_buff *skb,
				  u32 pid, unsigned int group, gfp_t flags)
{
	int err;

	NETLINK_CB(skb).dst_group = group;

	err = netlink_broadcast(sk, skb, pid, group, flags);
	if (err > 0)
		err = 0;

	return err;
}

/**
 * nlmsg_unicast - unicast a netlink message
 * @sk: netlink socket to spread message to
 * @skb: netlink message as socket buffer
 * @pid: netlink pid of the destination socket
 */
static inline int nlmsg_unicast(struct sock *sk, struct sk_buff *skb, u32 pid)
{
	int err;

	err = netlink_unicast(sk, skb, pid, MSG_DONTWAIT);
	if (err > 0)
		err = 0;

	return err;
}

/**
 * nlmsg_for_each_msg - iterate over a stream of messages
 * @pos: loop counter, set to current message
 * @head: head of message stream
 * @len: length of message stream
 * @rem: initialized to len, holds bytes currently remaining in stream
 */
#define nlmsg_for_each_msg(pos, head, len, rem) \
	for (pos = head, rem = len; \
	     nlmsg_ok(pos, rem); \
	     pos = nlmsg_next(pos, &(rem)))

/**************************************************************************
 * Netlink Attributes
 **************************************************************************/

/**
 * nla_attr_size - length of attribute not including padding
 * @payload: length of payload
 */
static inline int nla_attr_size(int payload)
{
	return NLA_HDRLEN + payload;
}

/**
 * nla_total_size - total length of attribute including padding
 * @payload: length of payload
 */
static inline int nla_total_size(int payload)
{
	return NLA_ALIGN(nla_attr_size(payload));
}

/**
 * nla_padlen - length of padding at the tail of attribute
 * @payload: length of payload
 */
static inline int nla_padlen(int payload)
{
	return nla_total_size(payload) - nla_attr_size(payload);
}

/**
 * nla_data - head of payload
 * @nla: netlink attribute
 */
static inline void *nla_data(const struct nlattr *nla)
{
	return (char *) nla + NLA_HDRLEN;
}

/**
 * nla_len - length of payload
 * @nla: netlink attribute
 */
static inline int nla_len(const struct nlattr *nla)
{
	return nla->nla_len - NLA_HDRLEN;
}

/**
 * nla_ok - check if the netlink attribute fits into the remaining bytes
 * @nla: netlink attribute
 * @remaining: number of bytes remaining in attribute stream
 */
static inline int nla_ok(const struct nlattr *nla, int remaining)
{
	return remaining >= sizeof(*nla) &&
	       nla->nla_len >= sizeof(*nla) &&
	       nla->nla_len <= remaining;
}

/**
 * nla_next - next netlink attribte in attribute stream
 * @nla: netlink attribute
 * @remaining: number of bytes remaining in attribute stream
 *
 * Returns the next netlink attribute in the attribute stream and
 * decrements remaining by the size of the current attribute.
 */
static inline struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
{
	int totlen = NLA_ALIGN(nla->nla_len);

	*remaining -= totlen;
	return (struct nlattr *) ((char *) nla + totlen);
}

/**
 * nla_find_nested - find attribute in a set of nested attributes
 * @nla: attribute containing the nested attributes
 * @attrtype: type of attribute to look for
 *
 * Returns the first attribute which matches the specified type.
 */
static inline struct nlattr *nla_find_nested(struct nlattr *nla, int attrtype)
{
	return nla_find(nla_data(nla), nla_len(nla), attrtype);
}

/**
 * nla_parse_nested - parse nested attributes
 * @tb: destination array with maxtype+1 elements
 * @maxtype: maximum attribute type to be expected
 * @nla: attribute containing the nested attributes
 * @policy: validation policy
 *
 * See nla_parse()
 */
static inline int nla_parse_nested(struct nlattr *tb[], int maxtype,
				   struct nlattr *nla,
				   struct nla_policy *policy)
{
	return nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy);
}
/**
 * nla_put_u8 - Add a u16 netlink attribute to a socket buffer
 * @skb: socket buffer to add attribute to
 * @attrtype: attribute type
 * @value: numeric value
 */
static inline int nla_put_u8(struct sk_buff *skb, int attrtype, u8 value)
{
	return nla_put(skb, attrtype, sizeof(u8), &value);
}

/**
 * nla_put_u16 - Add a u16 netlink attribute to a socket buffer
 * @skb: socket buffer to add attribute to
 * @attrtype: attribute type
 * @value: numeric value
 */
static inline int nla_put_u16(struct sk_buff *skb, int attrtype, u16 value)
{
	return nla_put(skb, attrtype, sizeof(u16), &value);
}

/**
 * nla_put_u32 - Add a u32 netlink attribute to a socket buffer
 * @skb: socket buffer to add attribute to
 * @attrtype: attribute type
 * @value: numeric value
 */
static inline int nla_put_u32(struct sk_buff *skb, int attrtype, u32 value)
{
	return nla_put(skb, attrtype, sizeof(u32), &value);
}

/**
 * nla_put_64 - Add a u64 netlink attribute to a socket buffer
 * @skb: socket buffer to add attribute to
 * @attrtype: attribute type
 * @value: numeric value
 */
static inline int nla_put_u64(struct sk_buff *skb, int attrtype, u64 value)
{
	return nla_put(skb, attrtype, sizeof(u64), &value);
}

/**
 * nla_put_string - Add a string netlink attribute to a socket buffer
 * @skb: socket buffer to add attribute to
 * @attrtype: attribute type
 * @str: NUL terminated string
 */
static inline int nla_put_string(struct sk_buff *skb, int attrtype,
				 const char *str)
{
	return nla_put(skb, attrtype, strlen(str) + 1, str);
}

/**
 * nla_put_flag - Add a flag netlink attribute to a socket buffer
 * @skb: socket buffer to add attribute to
 * @attrtype: attribute type
 */
static inline int nla_put_flag(struct sk_buff *skb, int attrtype)
{
	return nla_put(skb, attrtype, 0, NULL);
}

/**
 * nla_put_msecs - Add a msecs netlink attribute to a socket buffer
 * @skb: socket buffer to add attribute to
 * @attrtype: attribute type
 * @jiffies: number of msecs in jiffies
 */
static inline int nla_put_msecs(struct sk_buff *skb, int attrtype,
				unsigned long jiffies)
{
	u64 tmp = jiffies_to_msecs(jiffies);
	return nla_put(skb, attrtype, sizeof(u64), &tmp);
}

#define NLA_PUT(skb, attrtype, attrlen, data) \
	do { \
		if (nla_put(skb, attrtype, attrlen, data) < 0) \
			goto nla_put_failure; \
	} while(0)

#define NLA_PUT_TYPE(skb, type, attrtype, value) \
	do { \
		type __tmp = value; \
		NLA_PUT(skb, attrtype, sizeof(type), &__tmp); \
	} while(0)

#define NLA_PUT_U8(skb, attrtype, value) \
	NLA_PUT_TYPE(skb, u8, attrtype, value)

#define NLA_PUT_U16(skb, attrtype, value) \
	NLA_PUT_TYPE(skb, u16, attrtype, value)

#define NLA_PUT_LE16(skb, attrtype, value) \
	NLA_PUT_TYPE(skb, __le16, attrtype, value)

#define NLA_PUT_U32(skb, attrtype, value) \
	NLA_PUT_TYPE(skb, u32, attrtype, value)

#define NLA_PUT_BE32(skb, attrtype, value) \
	NLA_PUT_TYPE(skb, __be32, attrtype, value)

#define NLA_PUT_U64(skb, attrtype, value) \
	NLA_PUT_TYPE(skb, u64, attrtype, value)

#define NLA_PUT_STRING(skb, attrtype, value) \
	NLA_PUT(skb, attrtype, strlen(value) + 1, value)

#define NLA_PUT_FLAG(skb, attrtype) \
	NLA_PUT(skb, attrtype, 0, NULL)

#define NLA_PUT_MSECS(skb, attrtype, jiffies) \
	NLA_PUT_U64(skb, attrtype, jiffies_to_msecs(jiffies))

/**
 * nla_get_u32 - return payload of u32 attribute
 * @nla: u32 netlink attribute
 */
static inline u32 nla_get_u32(struct nlattr *nla)
{
	return *(u32 *) nla_data(nla);
}

/**
 * nla_get_be32 - return payload of __be32 attribute
 * @nla: __be32 netlink attribute
 */
static inline __be32 nla_get_be32(struct nlattr *nla)
{
	return *(__be32 *) nla_data(nla);
}

/**
 * nla_get_u16 - return payload of u16 attribute
 * @nla: u16 netlink attribute
 */
static inline u16 nla_get_u16(struct nlattr *nla)
{
	return *(u16 *) nla_data(nla);
}

/**
 * nla_get_le16 - return payload of __le16 attribute
 * @nla: __le16 netlink attribute
 */
static inline __le16 nla_get_le16(struct nlattr *nla)
{
	return *(__le16 *) nla_data(nla);
}

/**
 * nla_get_u8 - return payload of u8 attribute
 * @nla: u8 netlink attribute
 */
static inline u8 nla_get_u8(struct nlattr *nla)
{
	return *(u8 *) nla_data(nla);
}

/**
 * nla_get_u64 - return payload of u64 attribute
 * @nla: u64 netlink attribute
 */
static inline u64 nla_get_u64(struct nlattr *nla)
{
	u64 tmp;

	nla_memcpy(&tmp, nla, sizeof(tmp));

	return tmp;
}

/**
 * nla_get_flag - return payload of flag attribute
 * @nla: flag netlink attribute
 */
static inline int nla_get_flag(struct nlattr *nla)
{
	return !!nla;
}

/**
 * nla_get_msecs - return payload of msecs attribute
 * @nla: msecs netlink attribute
 *
 * Returns the number of milliseconds in jiffies.
 */
static inline unsigned long nla_get_msecs(struct nlattr *nla)
{
	u64 msecs = nla_get_u64(nla);

	return msecs_to_jiffies((unsigned long) msecs);
}

/**
 * nla_nest_start - Start a new level of nested attributes
 * @skb: socket buffer to add attributes to
 * @attrtype: attribute type of container
 *
 * Returns the container attribute
 */
static inline struct nlattr *nla_nest_start(struct sk_buff *skb, int attrtype)
{
	struct nlattr *start = (struct nlattr *)skb_tail_pointer(skb);

	if (nla_put(skb, attrtype, 0, NULL) < 0)
		return NULL;

	return start;
}

/**
 * nla_nest_end - Finalize nesting of attributes
 * @skb: socket buffer the attribtues are stored in
 * @start: container attribute
 *
 * Corrects the container attribute header to include the all
 * appeneded attributes.
 *
 * Returns the total data length of the skb.
 */
static inline int nla_nest_end(struct sk_buff *skb, struct nlattr *start)
{
	start->nla_len = skb_tail_pointer(skb) - (unsigned char *)start;
	return skb->len;
}

/**
 * nla_nest_cancel - Cancel nesting of attributes
 * @skb: socket buffer the message is stored in
 * @start: container attribute
 *
 * Removes the container attribute and including all nested
 * attributes. Returns -1.
 */
static inline int nla_nest_cancel(struct sk_buff *skb, struct nlattr *start)
{
	return nlmsg_trim(skb, start);
}

/**
 * nla_validate_nested - Validate a stream of nested attributes
 * @start: container attribute
 * @maxtype: maximum attribute type to be expected
 * @policy: validation policy
 *
 * Validates all attributes in the nested attribute stream against the
 * specified policy. Attributes with a type exceeding maxtype will be
 * ignored. See documenation of struct nla_policy for more details.
 *
 * Returns 0 on success or a negative error code.
 */
static inline int nla_validate_nested(struct nlattr *start, int maxtype,
				      struct nla_policy *policy)
{
	return nla_validate(nla_data(start), nla_len(start), maxtype, policy);
}

/**
 * nla_for_each_attr - iterate over a stream of attributes
 * @pos: loop counter, set to current attribute
 * @head: head of attribute stream
 * @len: length of attribute stream
 * @rem: initialized to len, holds bytes currently remaining in stream
 */
#define nla_for_each_attr(pos, head, len, rem) \
	for (pos = head, rem = len; \
	     nla_ok(pos, rem); \
	     pos = nla_next(pos, &(rem)))

/**
 * nla_for_each_nested - iterate over nested attributes
 * @pos: loop counter, set to current attribute
 * @nla: attribute containing the nested attributes
 * @rem: initialized to len, holds bytes currently remaining in stream
 */
#define nla_for_each_nested(pos, nla, rem) \
	nla_for_each_attr(pos, nla_data(nla), nla_len(nla), rem)

#endif