xref: /openbmc/linux/include/net/netlink.h (revision 9ac8d3fb)
1 #ifndef __NET_NETLINK_H
2 #define __NET_NETLINK_H
3 
4 #include <linux/types.h>
5 #include <linux/netlink.h>
6 #include <linux/jiffies.h>
7 
8 /* ========================================================================
9  *         Netlink Messages and Attributes Interface (As Seen On TV)
10  * ------------------------------------------------------------------------
11  *                          Messages Interface
12  * ------------------------------------------------------------------------
13  *
14  * Message Format:
15  *    <--- nlmsg_total_size(payload)  --->
16  *    <-- nlmsg_msg_size(payload) ->
17  *   +----------+- - -+-------------+- - -+-------- - -
18  *   | nlmsghdr | Pad |   Payload   | Pad | nlmsghdr
19  *   +----------+- - -+-------------+- - -+-------- - -
20  *   nlmsg_data(nlh)---^                   ^
21  *   nlmsg_next(nlh)-----------------------+
22  *
23  * Payload Format:
24  *    <---------------------- nlmsg_len(nlh) --------------------->
25  *    <------ hdrlen ------>       <- nlmsg_attrlen(nlh, hdrlen) ->
26  *   +----------------------+- - -+--------------------------------+
27  *   |     Family Header    | Pad |           Attributes           |
28  *   +----------------------+- - -+--------------------------------+
29  *   nlmsg_attrdata(nlh, hdrlen)---^
30  *
31  * Data Structures:
32  *   struct nlmsghdr			netlink message header
33  *
34  * Message Construction:
35  *   nlmsg_new()			create a new netlink message
36  *   nlmsg_put()			add a netlink message to an skb
37  *   nlmsg_put_answer()			callback based nlmsg_put()
38  *   nlmsg_end()			finanlize netlink message
39  *   nlmsg_get_pos()			return current position in message
40  *   nlmsg_trim()			trim part of message
41  *   nlmsg_cancel()			cancel message construction
42  *   nlmsg_free()			free a netlink message
43  *
44  * Message Sending:
45  *   nlmsg_multicast()			multicast message to several groups
46  *   nlmsg_unicast()			unicast a message to a single socket
47  *   nlmsg_notify()			send notification message
48  *
49  * Message Length Calculations:
50  *   nlmsg_msg_size(payload)		length of message w/o padding
51  *   nlmsg_total_size(payload)		length of message w/ padding
52  *   nlmsg_padlen(payload)		length of padding at tail
53  *
54  * Message Payload Access:
55  *   nlmsg_data(nlh)			head of message payload
56  *   nlmsg_len(nlh)			length of message payload
57  *   nlmsg_attrdata(nlh, hdrlen)	head of attributes data
58  *   nlmsg_attrlen(nlh, hdrlen)		length of attributes data
59  *
60  * Message Parsing:
61  *   nlmsg_ok(nlh, remaining)		does nlh fit into remaining bytes?
62  *   nlmsg_next(nlh, remaining)		get next netlink message
63  *   nlmsg_parse()			parse attributes of a message
64  *   nlmsg_find_attr()			find an attribute in a message
65  *   nlmsg_for_each_msg()		loop over all messages
66  *   nlmsg_validate()			validate netlink message incl. attrs
67  *   nlmsg_for_each_attr()		loop over all attributes
68  *
69  * Misc:
70  *   nlmsg_report()			report back to application?
71  *
72  * ------------------------------------------------------------------------
73  *                          Attributes Interface
74  * ------------------------------------------------------------------------
75  *
76  * Attribute Format:
77  *    <------- nla_total_size(payload) ------->
78  *    <---- nla_attr_size(payload) ----->
79  *   +----------+- - -+- - - - - - - - - +- - -+-------- - -
80  *   |  Header  | Pad |     Payload      | Pad |  Header
81  *   +----------+- - -+- - - - - - - - - +- - -+-------- - -
82  *                     <- nla_len(nla) ->      ^
83  *   nla_data(nla)----^                        |
84  *   nla_next(nla)-----------------------------'
85  *
86  * Data Structures:
87  *   struct nlattr			netlink attribute header
88  *
89  * Attribute Construction:
90  *   nla_reserve(skb, type, len)	reserve room for an attribute
91  *   nla_reserve_nohdr(skb, len)	reserve room for an attribute w/o hdr
92  *   nla_put(skb, type, len, data)	add attribute to skb
93  *   nla_put_nohdr(skb, len, data)	add attribute w/o hdr
94  *   nla_append(skb, len, data)		append data to skb
95  *
96  * Attribute Construction for Basic Types:
97  *   nla_put_u8(skb, type, value)	add u8 attribute to skb
98  *   nla_put_u16(skb, type, value)	add u16 attribute to skb
99  *   nla_put_u32(skb, type, value)	add u32 attribute to skb
100  *   nla_put_u64(skb, type, value)	add u64 attribute to skb
101  *   nla_put_string(skb, type, str)	add string attribute to skb
102  *   nla_put_flag(skb, type)		add flag attribute to skb
103  *   nla_put_msecs(skb, type, jiffies)	add msecs attribute to skb
104  *
105  * Exceptions Based Attribute Construction:
106  *   NLA_PUT(skb, type, len, data)	add attribute to skb
107  *   NLA_PUT_U8(skb, type, value)	add u8 attribute to skb
108  *   NLA_PUT_U16(skb, type, value)	add u16 attribute to skb
109  *   NLA_PUT_U32(skb, type, value)	add u32 attribute to skb
110  *   NLA_PUT_U64(skb, type, value)	add u64 attribute to skb
111  *   NLA_PUT_STRING(skb, type, str)	add string attribute to skb
112  *   NLA_PUT_FLAG(skb, type)		add flag attribute to skb
113  *   NLA_PUT_MSECS(skb, type, jiffies)	add msecs attribute to skb
114  *
115  *   The meaning of these functions is equal to their lower case
116  *   variants but they jump to the label nla_put_failure in case
117  *   of a failure.
118  *
119  * Nested Attributes Construction:
120  *   nla_nest_start(skb, type)		start a nested attribute
121  *   nla_nest_end(skb, nla)		finalize a nested attribute
122  *   nla_nest_cancel(skb, nla)		cancel nested attribute construction
123  *
124  * Attribute Length Calculations:
125  *   nla_attr_size(payload)		length of attribute w/o padding
126  *   nla_total_size(payload)		length of attribute w/ padding
127  *   nla_padlen(payload)		length of padding
128  *
129  * Attribute Payload Access:
130  *   nla_data(nla)			head of attribute payload
131  *   nla_len(nla)			length of attribute payload
132  *
133  * Attribute Payload Access for Basic Types:
134  *   nla_get_u8(nla)			get payload for a u8 attribute
135  *   nla_get_u16(nla)			get payload for a u16 attribute
136  *   nla_get_u32(nla)			get payload for a u32 attribute
137  *   nla_get_u64(nla)			get payload for a u64 attribute
138  *   nla_get_flag(nla)			return 1 if flag is true
139  *   nla_get_msecs(nla)			get payload for a msecs attribute
140  *
141  * Attribute Misc:
142  *   nla_memcpy(dest, nla, count)	copy attribute into memory
143  *   nla_memcmp(nla, data, size)	compare attribute with memory area
144  *   nla_strlcpy(dst, nla, size)	copy attribute to a sized string
145  *   nla_strcmp(nla, str)		compare attribute with string
146  *
147  * Attribute Parsing:
148  *   nla_ok(nla, remaining)		does nla fit into remaining bytes?
149  *   nla_next(nla, remaining)		get next netlink attribute
150  *   nla_validate()			validate a stream of attributes
151  *   nla_validate_nested()		validate a stream of nested attributes
152  *   nla_find()				find attribute in stream of attributes
153  *   nla_find_nested()			find attribute in nested attributes
154  *   nla_parse()			parse and validate stream of attrs
155  *   nla_parse_nested()			parse nested attribuets
156  *   nla_for_each_attr()		loop over all attributes
157  *   nla_for_each_nested()		loop over the nested attributes
158  *=========================================================================
159  */
160 
161  /**
162   * Standard attribute types to specify validation policy
163   */
164 enum {
165 	NLA_UNSPEC,
166 	NLA_U8,
167 	NLA_U16,
168 	NLA_U32,
169 	NLA_U64,
170 	NLA_STRING,
171 	NLA_FLAG,
172 	NLA_MSECS,
173 	NLA_NESTED,
174 	NLA_NESTED_COMPAT,
175 	NLA_NUL_STRING,
176 	NLA_BINARY,
177 	__NLA_TYPE_MAX,
178 };
179 
180 #define NLA_TYPE_MAX (__NLA_TYPE_MAX - 1)
181 
182 /**
183  * struct nla_policy - attribute validation policy
184  * @type: Type of attribute or NLA_UNSPEC
185  * @len: Type specific length of payload
186  *
187  * Policies are defined as arrays of this struct, the array must be
188  * accessible by attribute type up to the highest identifier to be expected.
189  *
190  * Meaning of `len' field:
191  *    NLA_STRING           Maximum length of string
192  *    NLA_NUL_STRING       Maximum length of string (excluding NUL)
193  *    NLA_FLAG             Unused
194  *    NLA_BINARY           Maximum length of attribute payload
195  *    NLA_NESTED_COMPAT    Exact length of structure payload
196  *    All other            Exact length of attribute payload
197  *
198  * Example:
199  * static struct nla_policy my_policy[ATTR_MAX+1] __read_mostly = {
200  * 	[ATTR_FOO] = { .type = NLA_U16 },
201  *	[ATTR_BAR] = { .type = NLA_STRING, .len = BARSIZ },
202  *	[ATTR_BAZ] = { .len = sizeof(struct mystruct) },
203  * };
204  */
205 struct nla_policy {
206 	u16		type;
207 	u16		len;
208 };
209 
210 /**
211  * struct nl_info - netlink source information
212  * @nlh: Netlink message header of original request
213  * @pid: Netlink PID of requesting application
214  */
215 struct nl_info {
216 	struct nlmsghdr		*nlh;
217 	struct net		*nl_net;
218 	u32			pid;
219 };
220 
221 extern int		netlink_rcv_skb(struct sk_buff *skb,
222 					int (*cb)(struct sk_buff *,
223 						  struct nlmsghdr *));
224 extern int		nlmsg_notify(struct sock *sk, struct sk_buff *skb,
225 				     u32 pid, unsigned int group, int report,
226 				     gfp_t flags);
227 
228 extern int		nla_validate(struct nlattr *head, int len, int maxtype,
229 				     const struct nla_policy *policy);
230 extern int		nla_parse(struct nlattr *tb[], int maxtype,
231 				  struct nlattr *head, int len,
232 				  const struct nla_policy *policy);
233 extern struct nlattr *	nla_find(struct nlattr *head, int len, int attrtype);
234 extern size_t		nla_strlcpy(char *dst, const struct nlattr *nla,
235 				    size_t dstsize);
236 extern int		nla_memcpy(void *dest, struct nlattr *src, int count);
237 extern int		nla_memcmp(const struct nlattr *nla, const void *data,
238 				   size_t size);
239 extern int		nla_strcmp(const struct nlattr *nla, const char *str);
240 extern struct nlattr *	__nla_reserve(struct sk_buff *skb, int attrtype,
241 				      int attrlen);
242 extern void *		__nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
243 extern struct nlattr *	nla_reserve(struct sk_buff *skb, int attrtype,
244 				    int attrlen);
245 extern void *		nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
246 extern void		__nla_put(struct sk_buff *skb, int attrtype,
247 				  int attrlen, const void *data);
248 extern void		__nla_put_nohdr(struct sk_buff *skb, int attrlen,
249 					const void *data);
250 extern int		nla_put(struct sk_buff *skb, int attrtype,
251 				int attrlen, const void *data);
252 extern int		nla_put_nohdr(struct sk_buff *skb, int attrlen,
253 				      const void *data);
254 extern int		nla_append(struct sk_buff *skb, int attrlen,
255 				   const void *data);
256 
257 /**************************************************************************
258  * Netlink Messages
259  **************************************************************************/
260 
261 /**
262  * nlmsg_msg_size - length of netlink message not including padding
263  * @payload: length of message payload
264  */
265 static inline int nlmsg_msg_size(int payload)
266 {
267 	return NLMSG_HDRLEN + payload;
268 }
269 
270 /**
271  * nlmsg_total_size - length of netlink message including padding
272  * @payload: length of message payload
273  */
274 static inline int nlmsg_total_size(int payload)
275 {
276 	return NLMSG_ALIGN(nlmsg_msg_size(payload));
277 }
278 
279 /**
280  * nlmsg_padlen - length of padding at the message's tail
281  * @payload: length of message payload
282  */
283 static inline int nlmsg_padlen(int payload)
284 {
285 	return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
286 }
287 
288 /**
289  * nlmsg_data - head of message payload
290  * @nlh: netlink messsage header
291  */
292 static inline void *nlmsg_data(const struct nlmsghdr *nlh)
293 {
294 	return (unsigned char *) nlh + NLMSG_HDRLEN;
295 }
296 
297 /**
298  * nlmsg_len - length of message payload
299  * @nlh: netlink message header
300  */
301 static inline int nlmsg_len(const struct nlmsghdr *nlh)
302 {
303 	return nlh->nlmsg_len - NLMSG_HDRLEN;
304 }
305 
306 /**
307  * nlmsg_attrdata - head of attributes data
308  * @nlh: netlink message header
309  * @hdrlen: length of family specific header
310  */
311 static inline struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh,
312 					    int hdrlen)
313 {
314 	unsigned char *data = nlmsg_data(nlh);
315 	return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
316 }
317 
318 /**
319  * nlmsg_attrlen - length of attributes data
320  * @nlh: netlink message header
321  * @hdrlen: length of family specific header
322  */
323 static inline int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
324 {
325 	return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);
326 }
327 
328 /**
329  * nlmsg_ok - check if the netlink message fits into the remaining bytes
330  * @nlh: netlink message header
331  * @remaining: number of bytes remaining in message stream
332  */
333 static inline int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
334 {
335 	return (remaining >= sizeof(struct nlmsghdr) &&
336 		nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
337 		nlh->nlmsg_len <= remaining);
338 }
339 
340 /**
341  * nlmsg_next - next netlink message in message stream
342  * @nlh: netlink message header
343  * @remaining: number of bytes remaining in message stream
344  *
345  * Returns the next netlink message in the message stream and
346  * decrements remaining by the size of the current message.
347  */
348 static inline struct nlmsghdr *nlmsg_next(struct nlmsghdr *nlh, int *remaining)
349 {
350 	int totlen = NLMSG_ALIGN(nlh->nlmsg_len);
351 
352 	*remaining -= totlen;
353 
354 	return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
355 }
356 
357 /**
358  * nlmsg_parse - parse attributes of a netlink message
359  * @nlh: netlink message header
360  * @hdrlen: length of family specific header
361  * @tb: destination array with maxtype+1 elements
362  * @maxtype: maximum attribute type to be expected
363  * @policy: validation policy
364  *
365  * See nla_parse()
366  */
367 static inline int nlmsg_parse(struct nlmsghdr *nlh, int hdrlen,
368 			      struct nlattr *tb[], int maxtype,
369 			      const struct nla_policy *policy)
370 {
371 	if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
372 		return -EINVAL;
373 
374 	return nla_parse(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
375 			 nlmsg_attrlen(nlh, hdrlen), policy);
376 }
377 
378 /**
379  * nlmsg_find_attr - find a specific attribute in a netlink message
380  * @nlh: netlink message header
381  * @hdrlen: length of familiy specific header
382  * @attrtype: type of attribute to look for
383  *
384  * Returns the first attribute which matches the specified type.
385  */
386 static inline struct nlattr *nlmsg_find_attr(struct nlmsghdr *nlh,
387 					     int hdrlen, int attrtype)
388 {
389 	return nla_find(nlmsg_attrdata(nlh, hdrlen),
390 			nlmsg_attrlen(nlh, hdrlen), attrtype);
391 }
392 
393 /**
394  * nlmsg_validate - validate a netlink message including attributes
395  * @nlh: netlinket message header
396  * @hdrlen: length of familiy specific header
397  * @maxtype: maximum attribute type to be expected
398  * @policy: validation policy
399  */
400 static inline int nlmsg_validate(struct nlmsghdr *nlh, int hdrlen, int maxtype,
401 				 const struct nla_policy *policy)
402 {
403 	if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
404 		return -EINVAL;
405 
406 	return nla_validate(nlmsg_attrdata(nlh, hdrlen),
407 			    nlmsg_attrlen(nlh, hdrlen), maxtype, policy);
408 }
409 
410 /**
411  * nlmsg_report - need to report back to application?
412  * @nlh: netlink message header
413  *
414  * Returns 1 if a report back to the application is requested.
415  */
416 static inline int nlmsg_report(struct nlmsghdr *nlh)
417 {
418 	return !!(nlh->nlmsg_flags & NLM_F_ECHO);
419 }
420 
421 /**
422  * nlmsg_for_each_attr - iterate over a stream of attributes
423  * @pos: loop counter, set to current attribute
424  * @nlh: netlink message header
425  * @hdrlen: length of familiy specific header
426  * @rem: initialized to len, holds bytes currently remaining in stream
427  */
428 #define nlmsg_for_each_attr(pos, nlh, hdrlen, rem) \
429 	nla_for_each_attr(pos, nlmsg_attrdata(nlh, hdrlen), \
430 			  nlmsg_attrlen(nlh, hdrlen), rem)
431 
432 #if 0
433 /* FIXME: Enable once all users have been converted */
434 
435 /**
436  * __nlmsg_put - Add a new netlink message to an skb
437  * @skb: socket buffer to store message in
438  * @pid: netlink process id
439  * @seq: sequence number of message
440  * @type: message type
441  * @payload: length of message payload
442  * @flags: message flags
443  *
444  * The caller is responsible to ensure that the skb provides enough
445  * tailroom for both the netlink header and payload.
446  */
447 static inline struct nlmsghdr *__nlmsg_put(struct sk_buff *skb, u32 pid,
448 					   u32 seq, int type, int payload,
449 					   int flags)
450 {
451 	struct nlmsghdr *nlh;
452 
453 	nlh = (struct nlmsghdr *) skb_put(skb, nlmsg_total_size(payload));
454 	nlh->nlmsg_type = type;
455 	nlh->nlmsg_len = nlmsg_msg_size(payload);
456 	nlh->nlmsg_flags = flags;
457 	nlh->nlmsg_pid = pid;
458 	nlh->nlmsg_seq = seq;
459 
460 	memset((unsigned char *) nlmsg_data(nlh) + payload, 0,
461 	       nlmsg_padlen(payload));
462 
463 	return nlh;
464 }
465 #endif
466 
467 /**
468  * nlmsg_put - Add a new netlink message to an skb
469  * @skb: socket buffer to store message in
470  * @pid: netlink process id
471  * @seq: sequence number of message
472  * @type: message type
473  * @payload: length of message payload
474  * @flags: message flags
475  *
476  * Returns NULL if the tailroom of the skb is insufficient to store
477  * the message header and payload.
478  */
479 static inline struct nlmsghdr *nlmsg_put(struct sk_buff *skb, u32 pid, u32 seq,
480 					 int type, int payload, int flags)
481 {
482 	if (unlikely(skb_tailroom(skb) < nlmsg_total_size(payload)))
483 		return NULL;
484 
485 	return __nlmsg_put(skb, pid, seq, type, payload, flags);
486 }
487 
488 /**
489  * nlmsg_put_answer - Add a new callback based netlink message to an skb
490  * @skb: socket buffer to store message in
491  * @cb: netlink callback
492  * @type: message type
493  * @payload: length of message payload
494  * @flags: message flags
495  *
496  * Returns NULL if the tailroom of the skb is insufficient to store
497  * the message header and payload.
498  */
499 static inline struct nlmsghdr *nlmsg_put_answer(struct sk_buff *skb,
500 						struct netlink_callback *cb,
501 						int type, int payload,
502 						int flags)
503 {
504 	return nlmsg_put(skb, NETLINK_CB(cb->skb).pid, cb->nlh->nlmsg_seq,
505 			 type, payload, flags);
506 }
507 
508 /**
509  * nlmsg_new - Allocate a new netlink message
510  * @payload: size of the message payload
511  * @flags: the type of memory to allocate.
512  *
513  * Use NLMSG_DEFAULT_SIZE if the size of the payload isn't known
514  * and a good default is needed.
515  */
516 static inline struct sk_buff *nlmsg_new(size_t payload, gfp_t flags)
517 {
518 	return alloc_skb(nlmsg_total_size(payload), flags);
519 }
520 
521 /**
522  * nlmsg_end - Finalize a netlink message
523  * @skb: socket buffer the message is stored in
524  * @nlh: netlink message header
525  *
526  * Corrects the netlink message header to include the appeneded
527  * attributes. Only necessary if attributes have been added to
528  * the message.
529  *
530  * Returns the total data length of the skb.
531  */
532 static inline int nlmsg_end(struct sk_buff *skb, struct nlmsghdr *nlh)
533 {
534 	nlh->nlmsg_len = skb_tail_pointer(skb) - (unsigned char *)nlh;
535 
536 	return skb->len;
537 }
538 
539 /**
540  * nlmsg_get_pos - return current position in netlink message
541  * @skb: socket buffer the message is stored in
542  *
543  * Returns a pointer to the current tail of the message.
544  */
545 static inline void *nlmsg_get_pos(struct sk_buff *skb)
546 {
547 	return skb_tail_pointer(skb);
548 }
549 
550 /**
551  * nlmsg_trim - Trim message to a mark
552  * @skb: socket buffer the message is stored in
553  * @mark: mark to trim to
554  *
555  * Trims the message to the provided mark.
556  */
557 static inline void nlmsg_trim(struct sk_buff *skb, const void *mark)
558 {
559 	if (mark)
560 		skb_trim(skb, (unsigned char *) mark - skb->data);
561 }
562 
563 /**
564  * nlmsg_cancel - Cancel construction of a netlink message
565  * @skb: socket buffer the message is stored in
566  * @nlh: netlink message header
567  *
568  * Removes the complete netlink message including all
569  * attributes from the socket buffer again.
570  */
571 static inline void nlmsg_cancel(struct sk_buff *skb, struct nlmsghdr *nlh)
572 {
573 	nlmsg_trim(skb, nlh);
574 }
575 
576 /**
577  * nlmsg_free - free a netlink message
578  * @skb: socket buffer of netlink message
579  */
580 static inline void nlmsg_free(struct sk_buff *skb)
581 {
582 	kfree_skb(skb);
583 }
584 
585 /**
586  * nlmsg_multicast - multicast a netlink message
587  * @sk: netlink socket to spread messages to
588  * @skb: netlink message as socket buffer
589  * @pid: own netlink pid to avoid sending to yourself
590  * @group: multicast group id
591  * @flags: allocation flags
592  */
593 static inline int nlmsg_multicast(struct sock *sk, struct sk_buff *skb,
594 				  u32 pid, unsigned int group, gfp_t flags)
595 {
596 	int err;
597 
598 	NETLINK_CB(skb).dst_group = group;
599 
600 	err = netlink_broadcast(sk, skb, pid, group, flags);
601 	if (err > 0)
602 		err = 0;
603 
604 	return err;
605 }
606 
607 /**
608  * nlmsg_unicast - unicast a netlink message
609  * @sk: netlink socket to spread message to
610  * @skb: netlink message as socket buffer
611  * @pid: netlink pid of the destination socket
612  */
613 static inline int nlmsg_unicast(struct sock *sk, struct sk_buff *skb, u32 pid)
614 {
615 	int err;
616 
617 	err = netlink_unicast(sk, skb, pid, MSG_DONTWAIT);
618 	if (err > 0)
619 		err = 0;
620 
621 	return err;
622 }
623 
624 /**
625  * nlmsg_for_each_msg - iterate over a stream of messages
626  * @pos: loop counter, set to current message
627  * @head: head of message stream
628  * @len: length of message stream
629  * @rem: initialized to len, holds bytes currently remaining in stream
630  */
631 #define nlmsg_for_each_msg(pos, head, len, rem) \
632 	for (pos = head, rem = len; \
633 	     nlmsg_ok(pos, rem); \
634 	     pos = nlmsg_next(pos, &(rem)))
635 
636 /**************************************************************************
637  * Netlink Attributes
638  **************************************************************************/
639 
640 /**
641  * nla_attr_size - length of attribute not including padding
642  * @payload: length of payload
643  */
644 static inline int nla_attr_size(int payload)
645 {
646 	return NLA_HDRLEN + payload;
647 }
648 
649 /**
650  * nla_total_size - total length of attribute including padding
651  * @payload: length of payload
652  */
653 static inline int nla_total_size(int payload)
654 {
655 	return NLA_ALIGN(nla_attr_size(payload));
656 }
657 
658 /**
659  * nla_padlen - length of padding at the tail of attribute
660  * @payload: length of payload
661  */
662 static inline int nla_padlen(int payload)
663 {
664 	return nla_total_size(payload) - nla_attr_size(payload);
665 }
666 
667 /**
668  * nla_type - attribute type
669  * @nla: netlink attribute
670  */
671 static inline int nla_type(const struct nlattr *nla)
672 {
673 	return nla->nla_type & NLA_TYPE_MASK;
674 }
675 
676 /**
677  * nla_data - head of payload
678  * @nla: netlink attribute
679  */
680 static inline void *nla_data(const struct nlattr *nla)
681 {
682 	return (char *) nla + NLA_HDRLEN;
683 }
684 
685 /**
686  * nla_len - length of payload
687  * @nla: netlink attribute
688  */
689 static inline int nla_len(const struct nlattr *nla)
690 {
691 	return nla->nla_len - NLA_HDRLEN;
692 }
693 
694 /**
695  * nla_ok - check if the netlink attribute fits into the remaining bytes
696  * @nla: netlink attribute
697  * @remaining: number of bytes remaining in attribute stream
698  */
699 static inline int nla_ok(const struct nlattr *nla, int remaining)
700 {
701 	return remaining >= (int) sizeof(*nla) &&
702 	       nla->nla_len >= sizeof(*nla) &&
703 	       nla->nla_len <= remaining;
704 }
705 
706 /**
707  * nla_next - next netlink attribute in attribute stream
708  * @nla: netlink attribute
709  * @remaining: number of bytes remaining in attribute stream
710  *
711  * Returns the next netlink attribute in the attribute stream and
712  * decrements remaining by the size of the current attribute.
713  */
714 static inline struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
715 {
716 	int totlen = NLA_ALIGN(nla->nla_len);
717 
718 	*remaining -= totlen;
719 	return (struct nlattr *) ((char *) nla + totlen);
720 }
721 
722 /**
723  * nla_find_nested - find attribute in a set of nested attributes
724  * @nla: attribute containing the nested attributes
725  * @attrtype: type of attribute to look for
726  *
727  * Returns the first attribute which matches the specified type.
728  */
729 static inline struct nlattr *nla_find_nested(struct nlattr *nla, int attrtype)
730 {
731 	return nla_find(nla_data(nla), nla_len(nla), attrtype);
732 }
733 
734 /**
735  * nla_parse_nested - parse nested attributes
736  * @tb: destination array with maxtype+1 elements
737  * @maxtype: maximum attribute type to be expected
738  * @nla: attribute containing the nested attributes
739  * @policy: validation policy
740  *
741  * See nla_parse()
742  */
743 static inline int nla_parse_nested(struct nlattr *tb[], int maxtype,
744 				   struct nlattr *nla,
745 				   const struct nla_policy *policy)
746 {
747 	return nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy);
748 }
749 
750 /**
751  * nla_put_u8 - Add a u8 netlink attribute to a socket buffer
752  * @skb: socket buffer to add attribute to
753  * @attrtype: attribute type
754  * @value: numeric value
755  */
756 static inline int nla_put_u8(struct sk_buff *skb, int attrtype, u8 value)
757 {
758 	return nla_put(skb, attrtype, sizeof(u8), &value);
759 }
760 
761 /**
762  * nla_put_u16 - Add a u16 netlink attribute to a socket buffer
763  * @skb: socket buffer to add attribute to
764  * @attrtype: attribute type
765  * @value: numeric value
766  */
767 static inline int nla_put_u16(struct sk_buff *skb, int attrtype, u16 value)
768 {
769 	return nla_put(skb, attrtype, sizeof(u16), &value);
770 }
771 
772 /**
773  * nla_put_u32 - Add a u32 netlink attribute to a socket buffer
774  * @skb: socket buffer to add attribute to
775  * @attrtype: attribute type
776  * @value: numeric value
777  */
778 static inline int nla_put_u32(struct sk_buff *skb, int attrtype, u32 value)
779 {
780 	return nla_put(skb, attrtype, sizeof(u32), &value);
781 }
782 
783 /**
784  * nla_put_64 - Add a u64 netlink attribute to a socket buffer
785  * @skb: socket buffer to add attribute to
786  * @attrtype: attribute type
787  * @value: numeric value
788  */
789 static inline int nla_put_u64(struct sk_buff *skb, int attrtype, u64 value)
790 {
791 	return nla_put(skb, attrtype, sizeof(u64), &value);
792 }
793 
794 /**
795  * nla_put_string - Add a string netlink attribute to a socket buffer
796  * @skb: socket buffer to add attribute to
797  * @attrtype: attribute type
798  * @str: NUL terminated string
799  */
800 static inline int nla_put_string(struct sk_buff *skb, int attrtype,
801 				 const char *str)
802 {
803 	return nla_put(skb, attrtype, strlen(str) + 1, str);
804 }
805 
806 /**
807  * nla_put_flag - Add a flag netlink attribute to a socket buffer
808  * @skb: socket buffer to add attribute to
809  * @attrtype: attribute type
810  */
811 static inline int nla_put_flag(struct sk_buff *skb, int attrtype)
812 {
813 	return nla_put(skb, attrtype, 0, NULL);
814 }
815 
816 /**
817  * nla_put_msecs - Add a msecs netlink attribute to a socket buffer
818  * @skb: socket buffer to add attribute to
819  * @attrtype: attribute type
820  * @jiffies: number of msecs in jiffies
821  */
822 static inline int nla_put_msecs(struct sk_buff *skb, int attrtype,
823 				unsigned long jiffies)
824 {
825 	u64 tmp = jiffies_to_msecs(jiffies);
826 	return nla_put(skb, attrtype, sizeof(u64), &tmp);
827 }
828 
829 #define NLA_PUT(skb, attrtype, attrlen, data) \
830 	do { \
831 		if (unlikely(nla_put(skb, attrtype, attrlen, data) < 0)) \
832 			goto nla_put_failure; \
833 	} while(0)
834 
835 #define NLA_PUT_TYPE(skb, type, attrtype, value) \
836 	do { \
837 		type __tmp = value; \
838 		NLA_PUT(skb, attrtype, sizeof(type), &__tmp); \
839 	} while(0)
840 
841 #define NLA_PUT_U8(skb, attrtype, value) \
842 	NLA_PUT_TYPE(skb, u8, attrtype, value)
843 
844 #define NLA_PUT_U16(skb, attrtype, value) \
845 	NLA_PUT_TYPE(skb, u16, attrtype, value)
846 
847 #define NLA_PUT_LE16(skb, attrtype, value) \
848 	NLA_PUT_TYPE(skb, __le16, attrtype, value)
849 
850 #define NLA_PUT_BE16(skb, attrtype, value) \
851 	NLA_PUT_TYPE(skb, __be16, attrtype, value)
852 
853 #define NLA_PUT_U32(skb, attrtype, value) \
854 	NLA_PUT_TYPE(skb, u32, attrtype, value)
855 
856 #define NLA_PUT_BE32(skb, attrtype, value) \
857 	NLA_PUT_TYPE(skb, __be32, attrtype, value)
858 
859 #define NLA_PUT_U64(skb, attrtype, value) \
860 	NLA_PUT_TYPE(skb, u64, attrtype, value)
861 
862 #define NLA_PUT_BE64(skb, attrtype, value) \
863 	NLA_PUT_TYPE(skb, __be64, attrtype, value)
864 
865 #define NLA_PUT_STRING(skb, attrtype, value) \
866 	NLA_PUT(skb, attrtype, strlen(value) + 1, value)
867 
868 #define NLA_PUT_FLAG(skb, attrtype) \
869 	NLA_PUT(skb, attrtype, 0, NULL)
870 
871 #define NLA_PUT_MSECS(skb, attrtype, jiffies) \
872 	NLA_PUT_U64(skb, attrtype, jiffies_to_msecs(jiffies))
873 
874 /**
875  * nla_get_u32 - return payload of u32 attribute
876  * @nla: u32 netlink attribute
877  */
878 static inline u32 nla_get_u32(struct nlattr *nla)
879 {
880 	return *(u32 *) nla_data(nla);
881 }
882 
883 /**
884  * nla_get_be32 - return payload of __be32 attribute
885  * @nla: __be32 netlink attribute
886  */
887 static inline __be32 nla_get_be32(struct nlattr *nla)
888 {
889 	return *(__be32 *) nla_data(nla);
890 }
891 
892 /**
893  * nla_get_u16 - return payload of u16 attribute
894  * @nla: u16 netlink attribute
895  */
896 static inline u16 nla_get_u16(struct nlattr *nla)
897 {
898 	return *(u16 *) nla_data(nla);
899 }
900 
901 /**
902  * nla_get_be16 - return payload of __be16 attribute
903  * @nla: __be16 netlink attribute
904  */
905 static inline __be16 nla_get_be16(struct nlattr *nla)
906 {
907 	return *(__be16 *) nla_data(nla);
908 }
909 
910 /**
911  * nla_get_le16 - return payload of __le16 attribute
912  * @nla: __le16 netlink attribute
913  */
914 static inline __le16 nla_get_le16(struct nlattr *nla)
915 {
916 	return *(__le16 *) nla_data(nla);
917 }
918 
919 /**
920  * nla_get_u8 - return payload of u8 attribute
921  * @nla: u8 netlink attribute
922  */
923 static inline u8 nla_get_u8(struct nlattr *nla)
924 {
925 	return *(u8 *) nla_data(nla);
926 }
927 
928 /**
929  * nla_get_u64 - return payload of u64 attribute
930  * @nla: u64 netlink attribute
931  */
932 static inline u64 nla_get_u64(struct nlattr *nla)
933 {
934 	u64 tmp;
935 
936 	nla_memcpy(&tmp, nla, sizeof(tmp));
937 
938 	return tmp;
939 }
940 
941 /**
942  * nla_get_flag - return payload of flag attribute
943  * @nla: flag netlink attribute
944  */
945 static inline int nla_get_flag(struct nlattr *nla)
946 {
947 	return !!nla;
948 }
949 
950 /**
951  * nla_get_msecs - return payload of msecs attribute
952  * @nla: msecs netlink attribute
953  *
954  * Returns the number of milliseconds in jiffies.
955  */
956 static inline unsigned long nla_get_msecs(struct nlattr *nla)
957 {
958 	u64 msecs = nla_get_u64(nla);
959 
960 	return msecs_to_jiffies((unsigned long) msecs);
961 }
962 
963 /**
964  * nla_nest_start - Start a new level of nested attributes
965  * @skb: socket buffer to add attributes to
966  * @attrtype: attribute type of container
967  *
968  * Returns the container attribute
969  */
970 static inline struct nlattr *nla_nest_start(struct sk_buff *skb, int attrtype)
971 {
972 	struct nlattr *start = (struct nlattr *)skb_tail_pointer(skb);
973 
974 	if (nla_put(skb, attrtype, 0, NULL) < 0)
975 		return NULL;
976 
977 	return start;
978 }
979 
980 /**
981  * nla_nest_end - Finalize nesting of attributes
982  * @skb: socket buffer the attributes are stored in
983  * @start: container attribute
984  *
985  * Corrects the container attribute header to include the all
986  * appeneded attributes.
987  *
988  * Returns the total data length of the skb.
989  */
990 static inline int nla_nest_end(struct sk_buff *skb, struct nlattr *start)
991 {
992 	start->nla_len = skb_tail_pointer(skb) - (unsigned char *)start;
993 	return skb->len;
994 }
995 
996 /**
997  * nla_nest_cancel - Cancel nesting of attributes
998  * @skb: socket buffer the message is stored in
999  * @start: container attribute
1000  *
1001  * Removes the container attribute and including all nested
1002  * attributes. Returns -EMSGSIZE
1003  */
1004 static inline void nla_nest_cancel(struct sk_buff *skb, struct nlattr *start)
1005 {
1006 	nlmsg_trim(skb, start);
1007 }
1008 
1009 /**
1010  * nla_validate_nested - Validate a stream of nested attributes
1011  * @start: container attribute
1012  * @maxtype: maximum attribute type to be expected
1013  * @policy: validation policy
1014  *
1015  * Validates all attributes in the nested attribute stream against the
1016  * specified policy. Attributes with a type exceeding maxtype will be
1017  * ignored. See documenation of struct nla_policy for more details.
1018  *
1019  * Returns 0 on success or a negative error code.
1020  */
1021 static inline int nla_validate_nested(struct nlattr *start, int maxtype,
1022 				      const struct nla_policy *policy)
1023 {
1024 	return nla_validate(nla_data(start), nla_len(start), maxtype, policy);
1025 }
1026 
1027 /**
1028  * nla_for_each_attr - iterate over a stream of attributes
1029  * @pos: loop counter, set to current attribute
1030  * @head: head of attribute stream
1031  * @len: length of attribute stream
1032  * @rem: initialized to len, holds bytes currently remaining in stream
1033  */
1034 #define nla_for_each_attr(pos, head, len, rem) \
1035 	for (pos = head, rem = len; \
1036 	     nla_ok(pos, rem); \
1037 	     pos = nla_next(pos, &(rem)))
1038 
1039 /**
1040  * nla_for_each_nested - iterate over nested attributes
1041  * @pos: loop counter, set to current attribute
1042  * @nla: attribute containing the nested attributes
1043  * @rem: initialized to len, holds bytes currently remaining in stream
1044  */
1045 #define nla_for_each_nested(pos, nla, rem) \
1046 	nla_for_each_attr(pos, nla_data(nla), nla_len(nla), rem)
1047 
1048 #endif
1049