1#ifndef __NET_GENERIC_NETLINK_H
2#define __NET_GENERIC_NETLINK_H
3
4#include <linux/genetlink.h>
5#include <net/netlink.h>
6#include <net/net_namespace.h>
7
8#define GENLMSG_DEFAULT_SIZE (NLMSG_DEFAULT_SIZE - GENL_HDRLEN)
9
10/**
11 * struct genl_multicast_group - generic netlink multicast group
12 * @name: name of the multicast group, names are per-family
13 */
14struct genl_multicast_group {
15	char			name[GENL_NAMSIZ];
16};
17
18struct genl_ops;
19struct genl_info;
20
21/**
22 * struct genl_family - generic netlink family
23 * @id: protocol family idenfitier
24 * @hdrsize: length of user specific header in bytes
25 * @name: name of family
26 * @version: protocol version
27 * @maxattr: maximum number of attributes supported
28 * @netnsok: set to true if the family can handle network
29 *	namespaces and should be presented in all of them
30 * @pre_doit: called before an operation's doit callback, it may
31 *	do additional, common, filtering and return an error
32 * @post_doit: called after an operation's doit callback, it may
33 *	undo operations done by pre_doit, for example release locks
34 * @attrbuf: buffer to store parsed attributes
35 * @family_list: family list
36 * @mcgrps: multicast groups used by this family (private)
37 * @n_mcgrps: number of multicast groups (private)
38 * @mcgrp_offset: starting number of multicast group IDs in this family
39 * @ops: the operations supported by this family (private)
40 * @n_ops: number of operations supported by this family (private)
41 */
42struct genl_family {
43	unsigned int		id;
44	unsigned int		hdrsize;
45	char			name[GENL_NAMSIZ];
46	unsigned int		version;
47	unsigned int		maxattr;
48	bool			netnsok;
49	bool			parallel_ops;
50	int			(*pre_doit)(const struct genl_ops *ops,
51					    struct sk_buff *skb,
52					    struct genl_info *info);
53	void			(*post_doit)(const struct genl_ops *ops,
54					     struct sk_buff *skb,
55					     struct genl_info *info);
56	struct nlattr **	attrbuf;	/* private */
57	const struct genl_ops *	ops;		/* private */
58	const struct genl_multicast_group *mcgrps; /* private */
59	unsigned int		n_ops;		/* private */
60	unsigned int		n_mcgrps;	/* private */
61	unsigned int		mcgrp_offset;	/* private */
62	struct list_head	family_list;	/* private */
63	struct module		*module;
64};
65
66/**
67 * struct genl_info - receiving information
68 * @snd_seq: sending sequence number
69 * @snd_portid: netlink portid of sender
70 * @nlhdr: netlink message header
71 * @genlhdr: generic netlink message header
72 * @userhdr: user specific header
73 * @attrs: netlink attributes
74 * @_net: network namespace
75 * @user_ptr: user pointers
76 * @dst_sk: destination socket
77 */
78struct genl_info {
79	u32			snd_seq;
80	u32			snd_portid;
81	struct nlmsghdr *	nlhdr;
82	struct genlmsghdr *	genlhdr;
83	void *			userhdr;
84	struct nlattr **	attrs;
85#ifdef CONFIG_NET_NS
86	struct net *		_net;
87#endif
88	void *			user_ptr[2];
89	struct sock *		dst_sk;
90};
91
92static inline struct net *genl_info_net(struct genl_info *info)
93{
94	return read_pnet(&info->_net);
95}
96
97static inline void genl_info_net_set(struct genl_info *info, struct net *net)
98{
99	write_pnet(&info->_net, net);
100}
101
102/**
103 * struct genl_ops - generic netlink operations
104 * @cmd: command identifier
105 * @internal_flags: flags used by the family
106 * @flags: flags
107 * @policy: attribute validation policy
108 * @doit: standard command callback
109 * @dumpit: callback for dumpers
110 * @done: completion callback for dumps
111 * @ops_list: operations list
112 */
113struct genl_ops {
114	const struct nla_policy	*policy;
115	int		       (*doit)(struct sk_buff *skb,
116				       struct genl_info *info);
117	int		       (*dumpit)(struct sk_buff *skb,
118					 struct netlink_callback *cb);
119	int		       (*done)(struct netlink_callback *cb);
120	u8			cmd;
121	u8			internal_flags;
122	u8			flags;
123};
124
125int __genl_register_family(struct genl_family *family);
126
127static inline int genl_register_family(struct genl_family *family)
128{
129	family->module = THIS_MODULE;
130	return __genl_register_family(family);
131}
132
133/**
134 * genl_register_family_with_ops - register a generic netlink family with ops
135 * @family: generic netlink family
136 * @ops: operations to be registered
137 * @n_ops: number of elements to register
138 *
139 * Registers the specified family and operations from the specified table.
140 * Only one family may be registered with the same family name or identifier.
141 *
142 * The family id may equal GENL_ID_GENERATE causing an unique id to
143 * be automatically generated and assigned.
144 *
145 * Either a doit or dumpit callback must be specified for every registered
146 * operation or the function will fail. Only one operation structure per
147 * command identifier may be registered.
148 *
149 * See include/net/genetlink.h for more documenation on the operations
150 * structure.
151 *
152 * Return 0 on success or a negative error code.
153 */
154static inline int
155_genl_register_family_with_ops_grps(struct genl_family *family,
156				    const struct genl_ops *ops, size_t n_ops,
157				    const struct genl_multicast_group *mcgrps,
158				    size_t n_mcgrps)
159{
160	family->module = THIS_MODULE;
161	family->ops = ops;
162	family->n_ops = n_ops;
163	family->mcgrps = mcgrps;
164	family->n_mcgrps = n_mcgrps;
165	return __genl_register_family(family);
166}
167
168#define genl_register_family_with_ops(family, ops)			\
169	_genl_register_family_with_ops_grps((family),			\
170					    (ops), ARRAY_SIZE(ops),	\
171					    NULL, 0)
172#define genl_register_family_with_ops_groups(family, ops, grps)	\
173	_genl_register_family_with_ops_grps((family),			\
174					    (ops), ARRAY_SIZE(ops),	\
175					    (grps), ARRAY_SIZE(grps))
176
177int genl_unregister_family(struct genl_family *family);
178void genl_notify(struct genl_family *family,
179		 struct sk_buff *skb, struct net *net, u32 portid,
180		 u32 group, struct nlmsghdr *nlh, gfp_t flags);
181
182struct sk_buff *genlmsg_new_unicast(size_t payload, struct genl_info *info,
183				    gfp_t flags);
184void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
185		  struct genl_family *family, int flags, u8 cmd);
186
187/**
188 * genlmsg_nlhdr - Obtain netlink header from user specified header
189 * @user_hdr: user header as returned from genlmsg_put()
190 * @family: generic netlink family
191 *
192 * Returns pointer to netlink header.
193 */
194static inline struct nlmsghdr *genlmsg_nlhdr(void *user_hdr,
195					     struct genl_family *family)
196{
197	return (struct nlmsghdr *)((char *)user_hdr -
198				   family->hdrsize -
199				   GENL_HDRLEN -
200				   NLMSG_HDRLEN);
201}
202
203/**
204 * genl_dump_check_consistent - check if sequence is consistent and advertise if not
205 * @cb: netlink callback structure that stores the sequence number
206 * @user_hdr: user header as returned from genlmsg_put()
207 * @family: generic netlink family
208 *
209 * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it
210 * simpler to use with generic netlink.
211 */
212static inline void genl_dump_check_consistent(struct netlink_callback *cb,
213					      void *user_hdr,
214					      struct genl_family *family)
215{
216	nl_dump_check_consistent(cb, genlmsg_nlhdr(user_hdr, family));
217}
218
219/**
220 * genlmsg_put_reply - Add generic netlink header to a reply message
221 * @skb: socket buffer holding the message
222 * @info: receiver info
223 * @family: generic netlink family
224 * @flags: netlink message flags
225 * @cmd: generic netlink command
226 *
227 * Returns pointer to user specific header
228 */
229static inline void *genlmsg_put_reply(struct sk_buff *skb,
230				      struct genl_info *info,
231				      struct genl_family *family,
232				      int flags, u8 cmd)
233{
234	return genlmsg_put(skb, info->snd_portid, info->snd_seq, family,
235			   flags, cmd);
236}
237
238/**
239 * genlmsg_end - Finalize a generic netlink message
240 * @skb: socket buffer the message is stored in
241 * @hdr: user specific header
242 */
243static inline int genlmsg_end(struct sk_buff *skb, void *hdr)
244{
245	return nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
246}
247
248/**
249 * genlmsg_cancel - Cancel construction of a generic netlink message
250 * @skb: socket buffer the message is stored in
251 * @hdr: generic netlink message header
252 */
253static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr)
254{
255	if (hdr)
256		nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
257}
258
259/**
260 * genlmsg_multicast_netns - multicast a netlink message to a specific netns
261 * @family: the generic netlink family
262 * @net: the net namespace
263 * @skb: netlink message as socket buffer
264 * @portid: own netlink portid to avoid sending to yourself
265 * @group: offset of multicast group in groups array
266 * @flags: allocation flags
267 */
268static inline int genlmsg_multicast_netns(struct genl_family *family,
269					  struct net *net, struct sk_buff *skb,
270					  u32 portid, unsigned int group, gfp_t flags)
271{
272	if (WARN_ON_ONCE(group >= family->n_mcgrps))
273		return -EINVAL;
274	group = family->mcgrp_offset + group;
275	return nlmsg_multicast(net->genl_sock, skb, portid, group, flags);
276}
277
278/**
279 * genlmsg_multicast - multicast a netlink message to the default netns
280 * @family: the generic netlink family
281 * @skb: netlink message as socket buffer
282 * @portid: own netlink portid to avoid sending to yourself
283 * @group: offset of multicast group in groups array
284 * @flags: allocation flags
285 */
286static inline int genlmsg_multicast(struct genl_family *family,
287				    struct sk_buff *skb, u32 portid,
288				    unsigned int group, gfp_t flags)
289{
290	return genlmsg_multicast_netns(family, &init_net, skb,
291				       portid, group, flags);
292}
293
294/**
295 * genlmsg_multicast_allns - multicast a netlink message to all net namespaces
296 * @family: the generic netlink family
297 * @skb: netlink message as socket buffer
298 * @portid: own netlink portid to avoid sending to yourself
299 * @group: offset of multicast group in groups array
300 * @flags: allocation flags
301 *
302 * This function must hold the RTNL or rcu_read_lock().
303 */
304int genlmsg_multicast_allns(struct genl_family *family,
305			    struct sk_buff *skb, u32 portid,
306			    unsigned int group, gfp_t flags);
307
308/**
309 * genlmsg_unicast - unicast a netlink message
310 * @skb: netlink message as socket buffer
311 * @portid: netlink portid of the destination socket
312 */
313static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid)
314{
315	return nlmsg_unicast(net->genl_sock, skb, portid);
316}
317
318/**
319 * genlmsg_reply - reply to a request
320 * @skb: netlink message to be sent back
321 * @info: receiver information
322 */
323static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info)
324{
325	return genlmsg_unicast(genl_info_net(info), skb, info->snd_portid);
326}
327
328/**
329 * gennlmsg_data - head of message payload
330 * @gnlh: genetlink message header
331 */
332static inline void *genlmsg_data(const struct genlmsghdr *gnlh)
333{
334	return ((unsigned char *) gnlh + GENL_HDRLEN);
335}
336
337/**
338 * genlmsg_len - length of message payload
339 * @gnlh: genetlink message header
340 */
341static inline int genlmsg_len(const struct genlmsghdr *gnlh)
342{
343	struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh -
344							NLMSG_HDRLEN);
345	return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
346}
347
348/**
349 * genlmsg_msg_size - length of genetlink message not including padding
350 * @payload: length of message payload
351 */
352static inline int genlmsg_msg_size(int payload)
353{
354	return GENL_HDRLEN + payload;
355}
356
357/**
358 * genlmsg_total_size - length of genetlink message including padding
359 * @payload: length of message payload
360 */
361static inline int genlmsg_total_size(int payload)
362{
363	return NLMSG_ALIGN(genlmsg_msg_size(payload));
364}
365
366/**
367 * genlmsg_new - Allocate a new generic netlink message
368 * @payload: size of the message payload
369 * @flags: the type of memory to allocate.
370 */
371static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
372{
373	return nlmsg_new(genlmsg_total_size(payload), flags);
374}
375
376/**
377 * genl_set_err - report error to genetlink broadcast listeners
378 * @family: the generic netlink family
379 * @net: the network namespace to report the error to
380 * @portid: the PORTID of a process that we want to skip (if any)
381 * @group: the broadcast group that will notice the error
382 * 	(this is the offset of the multicast group in the groups array)
383 * @code: error code, must be negative (as usual in kernelspace)
384 *
385 * This function returns the number of broadcast listeners that have set the
386 * NETLINK_RECV_NO_ENOBUFS socket option.
387 */
388static inline int genl_set_err(struct genl_family *family, struct net *net,
389			       u32 portid, u32 group, int code)
390{
391	if (WARN_ON_ONCE(group >= family->n_mcgrps))
392		return -EINVAL;
393	group = family->mcgrp_offset + group;
394	return netlink_set_err(net->genl_sock, portid, group, code);
395}
396
397static inline int genl_has_listeners(struct genl_family *family,
398				     struct sock *sk, unsigned int group)
399{
400	if (WARN_ON_ONCE(group >= family->n_mcgrps))
401		return -EINVAL;
402	group = family->mcgrp_offset + group;
403	return netlink_has_listeners(sk, group);
404}
405#endif	/* __NET_GENERIC_NETLINK_H */
406