xref: /openbmc/linux/include/net/genetlink.h (revision a8fe58ce)
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  */
14 struct genl_multicast_group {
15 	char			name[GENL_NAMSIZ];
16 };
17 
18 struct genl_ops;
19 struct 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  * @parallel_ops: operations can be called in parallel and aren't
31  *	synchronized by the core genetlink code
32  * @pre_doit: called before an operation's doit callback, it may
33  *	do additional, common, filtering and return an error
34  * @post_doit: called after an operation's doit callback, it may
35  *	undo operations done by pre_doit, for example release locks
36  * @mcast_bind: a socket bound to the given multicast group (which
37  *	is given as the offset into the groups array)
38  * @mcast_unbind: a socket was unbound from the given multicast group.
39  *	Note that unbind() will not be called symmetrically if the
40  *	generic netlink family is removed while there are still open
41  *	sockets.
42  * @attrbuf: buffer to store parsed attributes
43  * @family_list: family list
44  * @mcgrps: multicast groups used by this family (private)
45  * @n_mcgrps: number of multicast groups (private)
46  * @mcgrp_offset: starting number of multicast group IDs in this family
47  * @ops: the operations supported by this family (private)
48  * @n_ops: number of operations supported by this family (private)
49  */
50 struct genl_family {
51 	unsigned int		id;
52 	unsigned int		hdrsize;
53 	char			name[GENL_NAMSIZ];
54 	unsigned int		version;
55 	unsigned int		maxattr;
56 	bool			netnsok;
57 	bool			parallel_ops;
58 	int			(*pre_doit)(const struct genl_ops *ops,
59 					    struct sk_buff *skb,
60 					    struct genl_info *info);
61 	void			(*post_doit)(const struct genl_ops *ops,
62 					     struct sk_buff *skb,
63 					     struct genl_info *info);
64 	int			(*mcast_bind)(struct net *net, int group);
65 	void			(*mcast_unbind)(struct net *net, int group);
66 	struct nlattr **	attrbuf;	/* private */
67 	const struct genl_ops *	ops;		/* private */
68 	const struct genl_multicast_group *mcgrps; /* private */
69 	unsigned int		n_ops;		/* private */
70 	unsigned int		n_mcgrps;	/* private */
71 	unsigned int		mcgrp_offset;	/* private */
72 	struct list_head	family_list;	/* private */
73 	struct module		*module;
74 };
75 
76 /**
77  * struct genl_info - receiving information
78  * @snd_seq: sending sequence number
79  * @snd_portid: netlink portid of sender
80  * @nlhdr: netlink message header
81  * @genlhdr: generic netlink message header
82  * @userhdr: user specific header
83  * @attrs: netlink attributes
84  * @_net: network namespace
85  * @user_ptr: user pointers
86  * @dst_sk: destination socket
87  */
88 struct genl_info {
89 	u32			snd_seq;
90 	u32			snd_portid;
91 	struct nlmsghdr *	nlhdr;
92 	struct genlmsghdr *	genlhdr;
93 	void *			userhdr;
94 	struct nlattr **	attrs;
95 	possible_net_t		_net;
96 	void *			user_ptr[2];
97 	struct sock *		dst_sk;
98 };
99 
100 static inline struct net *genl_info_net(struct genl_info *info)
101 {
102 	return read_pnet(&info->_net);
103 }
104 
105 static inline void genl_info_net_set(struct genl_info *info, struct net *net)
106 {
107 	write_pnet(&info->_net, net);
108 }
109 
110 /**
111  * struct genl_ops - generic netlink operations
112  * @cmd: command identifier
113  * @internal_flags: flags used by the family
114  * @flags: flags
115  * @policy: attribute validation policy
116  * @doit: standard command callback
117  * @start: start callback for dumps
118  * @dumpit: callback for dumpers
119  * @done: completion callback for dumps
120  * @ops_list: operations list
121  */
122 struct genl_ops {
123 	const struct nla_policy	*policy;
124 	int		       (*doit)(struct sk_buff *skb,
125 				       struct genl_info *info);
126 	int		       (*start)(struct netlink_callback *cb);
127 	int		       (*dumpit)(struct sk_buff *skb,
128 					 struct netlink_callback *cb);
129 	int		       (*done)(struct netlink_callback *cb);
130 	u8			cmd;
131 	u8			internal_flags;
132 	u8			flags;
133 };
134 
135 int __genl_register_family(struct genl_family *family);
136 
137 static inline int genl_register_family(struct genl_family *family)
138 {
139 	family->module = THIS_MODULE;
140 	return __genl_register_family(family);
141 }
142 
143 /**
144  * genl_register_family_with_ops - register a generic netlink family with ops
145  * @family: generic netlink family
146  * @ops: operations to be registered
147  * @n_ops: number of elements to register
148  *
149  * Registers the specified family and operations from the specified table.
150  * Only one family may be registered with the same family name or identifier.
151  *
152  * The family id may equal GENL_ID_GENERATE causing an unique id to
153  * be automatically generated and assigned.
154  *
155  * Either a doit or dumpit callback must be specified for every registered
156  * operation or the function will fail. Only one operation structure per
157  * command identifier may be registered.
158  *
159  * See include/net/genetlink.h for more documenation on the operations
160  * structure.
161  *
162  * Return 0 on success or a negative error code.
163  */
164 static inline int
165 _genl_register_family_with_ops_grps(struct genl_family *family,
166 				    const struct genl_ops *ops, size_t n_ops,
167 				    const struct genl_multicast_group *mcgrps,
168 				    size_t n_mcgrps)
169 {
170 	family->module = THIS_MODULE;
171 	family->ops = ops;
172 	family->n_ops = n_ops;
173 	family->mcgrps = mcgrps;
174 	family->n_mcgrps = n_mcgrps;
175 	return __genl_register_family(family);
176 }
177 
178 #define genl_register_family_with_ops(family, ops)			\
179 	_genl_register_family_with_ops_grps((family),			\
180 					    (ops), ARRAY_SIZE(ops),	\
181 					    NULL, 0)
182 #define genl_register_family_with_ops_groups(family, ops, grps)	\
183 	_genl_register_family_with_ops_grps((family),			\
184 					    (ops), ARRAY_SIZE(ops),	\
185 					    (grps), ARRAY_SIZE(grps))
186 
187 int genl_unregister_family(struct genl_family *family);
188 void genl_notify(struct genl_family *family, struct sk_buff *skb,
189 		 struct genl_info *info, u32 group, gfp_t flags);
190 
191 struct sk_buff *genlmsg_new_unicast(size_t payload, struct genl_info *info,
192 				    gfp_t flags);
193 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
194 		  struct genl_family *family, int flags, u8 cmd);
195 
196 /**
197  * genlmsg_nlhdr - Obtain netlink header from user specified header
198  * @user_hdr: user header as returned from genlmsg_put()
199  * @family: generic netlink family
200  *
201  * Returns pointer to netlink header.
202  */
203 static inline struct nlmsghdr *genlmsg_nlhdr(void *user_hdr,
204 					     struct genl_family *family)
205 {
206 	return (struct nlmsghdr *)((char *)user_hdr -
207 				   family->hdrsize -
208 				   GENL_HDRLEN -
209 				   NLMSG_HDRLEN);
210 }
211 
212 /**
213  * genlmsg_parse - parse attributes of a genetlink message
214  * @nlh: netlink message header
215  * @family: genetlink message family
216  * @tb: destination array with maxtype+1 elements
217  * @maxtype: maximum attribute type to be expected
218  * @policy: validation policy
219  * */
220 static inline int genlmsg_parse(const struct nlmsghdr *nlh,
221 				const struct genl_family *family,
222 				struct nlattr *tb[], int maxtype,
223 				const struct nla_policy *policy)
224 {
225 	return nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype,
226 			   policy);
227 }
228 
229 /**
230  * genl_dump_check_consistent - check if sequence is consistent and advertise if not
231  * @cb: netlink callback structure that stores the sequence number
232  * @user_hdr: user header as returned from genlmsg_put()
233  * @family: generic netlink family
234  *
235  * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it
236  * simpler to use with generic netlink.
237  */
238 static inline void genl_dump_check_consistent(struct netlink_callback *cb,
239 					      void *user_hdr,
240 					      struct genl_family *family)
241 {
242 	nl_dump_check_consistent(cb, genlmsg_nlhdr(user_hdr, family));
243 }
244 
245 /**
246  * genlmsg_put_reply - Add generic netlink header to a reply message
247  * @skb: socket buffer holding the message
248  * @info: receiver info
249  * @family: generic netlink family
250  * @flags: netlink message flags
251  * @cmd: generic netlink command
252  *
253  * Returns pointer to user specific header
254  */
255 static inline void *genlmsg_put_reply(struct sk_buff *skb,
256 				      struct genl_info *info,
257 				      struct genl_family *family,
258 				      int flags, u8 cmd)
259 {
260 	return genlmsg_put(skb, info->snd_portid, info->snd_seq, family,
261 			   flags, cmd);
262 }
263 
264 /**
265  * genlmsg_end - Finalize a generic netlink message
266  * @skb: socket buffer the message is stored in
267  * @hdr: user specific header
268  */
269 static inline void genlmsg_end(struct sk_buff *skb, void *hdr)
270 {
271 	nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
272 }
273 
274 /**
275  * genlmsg_cancel - Cancel construction of a generic netlink message
276  * @skb: socket buffer the message is stored in
277  * @hdr: generic netlink message header
278  */
279 static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr)
280 {
281 	if (hdr)
282 		nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
283 }
284 
285 /**
286  * genlmsg_multicast_netns - multicast a netlink message to a specific netns
287  * @family: the generic netlink family
288  * @net: the net namespace
289  * @skb: netlink message as socket buffer
290  * @portid: own netlink portid to avoid sending to yourself
291  * @group: offset of multicast group in groups array
292  * @flags: allocation flags
293  */
294 static inline int genlmsg_multicast_netns(struct genl_family *family,
295 					  struct net *net, struct sk_buff *skb,
296 					  u32 portid, unsigned int group, gfp_t flags)
297 {
298 	if (WARN_ON_ONCE(group >= family->n_mcgrps))
299 		return -EINVAL;
300 	group = family->mcgrp_offset + group;
301 	return nlmsg_multicast(net->genl_sock, skb, portid, group, flags);
302 }
303 
304 /**
305  * genlmsg_multicast - multicast a netlink message to the default netns
306  * @family: the generic netlink family
307  * @skb: netlink message as socket buffer
308  * @portid: own netlink portid to avoid sending to yourself
309  * @group: offset of multicast group in groups array
310  * @flags: allocation flags
311  */
312 static inline int genlmsg_multicast(struct genl_family *family,
313 				    struct sk_buff *skb, u32 portid,
314 				    unsigned int group, gfp_t flags)
315 {
316 	return genlmsg_multicast_netns(family, &init_net, skb,
317 				       portid, group, flags);
318 }
319 
320 /**
321  * genlmsg_multicast_allns - multicast a netlink message to all net namespaces
322  * @family: the generic netlink family
323  * @skb: netlink message as socket buffer
324  * @portid: own netlink portid to avoid sending to yourself
325  * @group: offset of multicast group in groups array
326  * @flags: allocation flags
327  *
328  * This function must hold the RTNL or rcu_read_lock().
329  */
330 int genlmsg_multicast_allns(struct genl_family *family,
331 			    struct sk_buff *skb, u32 portid,
332 			    unsigned int group, gfp_t flags);
333 
334 /**
335  * genlmsg_unicast - unicast a netlink message
336  * @skb: netlink message as socket buffer
337  * @portid: netlink portid of the destination socket
338  */
339 static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid)
340 {
341 	return nlmsg_unicast(net->genl_sock, skb, portid);
342 }
343 
344 /**
345  * genlmsg_reply - reply to a request
346  * @skb: netlink message to be sent back
347  * @info: receiver information
348  */
349 static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info)
350 {
351 	return genlmsg_unicast(genl_info_net(info), skb, info->snd_portid);
352 }
353 
354 /**
355  * gennlmsg_data - head of message payload
356  * @gnlh: genetlink message header
357  */
358 static inline void *genlmsg_data(const struct genlmsghdr *gnlh)
359 {
360 	return ((unsigned char *) gnlh + GENL_HDRLEN);
361 }
362 
363 /**
364  * genlmsg_len - length of message payload
365  * @gnlh: genetlink message header
366  */
367 static inline int genlmsg_len(const struct genlmsghdr *gnlh)
368 {
369 	struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh -
370 							NLMSG_HDRLEN);
371 	return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
372 }
373 
374 /**
375  * genlmsg_msg_size - length of genetlink message not including padding
376  * @payload: length of message payload
377  */
378 static inline int genlmsg_msg_size(int payload)
379 {
380 	return GENL_HDRLEN + payload;
381 }
382 
383 /**
384  * genlmsg_total_size - length of genetlink message including padding
385  * @payload: length of message payload
386  */
387 static inline int genlmsg_total_size(int payload)
388 {
389 	return NLMSG_ALIGN(genlmsg_msg_size(payload));
390 }
391 
392 /**
393  * genlmsg_new - Allocate a new generic netlink message
394  * @payload: size of the message payload
395  * @flags: the type of memory to allocate.
396  */
397 static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
398 {
399 	return nlmsg_new(genlmsg_total_size(payload), flags);
400 }
401 
402 /**
403  * genl_set_err - report error to genetlink broadcast listeners
404  * @family: the generic netlink family
405  * @net: the network namespace to report the error to
406  * @portid: the PORTID of a process that we want to skip (if any)
407  * @group: the broadcast group that will notice the error
408  * 	(this is the offset of the multicast group in the groups array)
409  * @code: error code, must be negative (as usual in kernelspace)
410  *
411  * This function returns the number of broadcast listeners that have set the
412  * NETLINK_RECV_NO_ENOBUFS socket option.
413  */
414 static inline int genl_set_err(struct genl_family *family, struct net *net,
415 			       u32 portid, u32 group, int code)
416 {
417 	if (WARN_ON_ONCE(group >= family->n_mcgrps))
418 		return -EINVAL;
419 	group = family->mcgrp_offset + group;
420 	return netlink_set_err(net->genl_sock, portid, group, code);
421 }
422 
423 static inline int genl_has_listeners(struct genl_family *family,
424 				     struct net *net, unsigned int group)
425 {
426 	if (WARN_ON_ONCE(group >= family->n_mcgrps))
427 		return -EINVAL;
428 	group = family->mcgrp_offset + group;
429 	return netlink_has_listeners(net->genl_sock, group);
430 }
431 #endif	/* __NET_GENERIC_NETLINK_H */
432