1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __NET_GENERIC_NETLINK_H
3 #define __NET_GENERIC_NETLINK_H
4 
5 #include <linux/genetlink.h>
6 #include <net/netlink.h>
7 #include <net/net_namespace.h>
8 
9 #define GENLMSG_DEFAULT_SIZE (NLMSG_DEFAULT_SIZE - GENL_HDRLEN)
10 
11 /**
12  * struct genl_multicast_group - generic netlink multicast group
13  * @name: name of the multicast group, names are per-family
14  */
15 struct genl_multicast_group {
16 	char			name[GENL_NAMSIZ];
17 	u8			flags;
18 };
19 
20 struct genl_ops;
21 struct genl_info;
22 
23 /**
24  * struct genl_family - generic netlink family
25  * @id: protocol family identifier (private)
26  * @hdrsize: length of user specific header in bytes
27  * @name: name of family
28  * @version: protocol version
29  * @maxattr: maximum number of attributes supported
30  * @policy: netlink policy
31  * @netnsok: set to true if the family can handle network
32  *	namespaces and should be presented in all of them
33  * @parallel_ops: operations can be called in parallel and aren't
34  *	synchronized by the core genetlink code
35  * @pre_doit: called before an operation's doit callback, it may
36  *	do additional, common, filtering and return an error
37  * @post_doit: called after an operation's doit callback, it may
38  *	undo operations done by pre_doit, for example release locks
39  * @mcgrps: multicast groups used by this family
40  * @n_mcgrps: number of multicast groups
41  * @mcgrp_offset: starting number of multicast group IDs in this family
42  *	(private)
43  * @ops: the operations supported by this family
44  * @n_ops: number of operations supported by this family
45  * @small_ops: the small-struct operations supported by this family
46  * @n_small_ops: number of small-struct operations supported by this family
47  */
48 struct genl_family {
49 	int			id;		/* private */
50 	unsigned int		hdrsize;
51 	char			name[GENL_NAMSIZ];
52 	unsigned int		version;
53 	unsigned int		maxattr;
54 	unsigned int		mcgrp_offset;	/* private */
55 	u8			netnsok:1;
56 	u8			parallel_ops:1;
57 	u8			n_ops;
58 	u8			n_small_ops;
59 	u8			n_mcgrps;
60 	const struct nla_policy *policy;
61 	int			(*pre_doit)(const struct genl_ops *ops,
62 					    struct sk_buff *skb,
63 					    struct genl_info *info);
64 	void			(*post_doit)(const struct genl_ops *ops,
65 					     struct sk_buff *skb,
66 					     struct genl_info *info);
67 	const struct genl_ops *	ops;
68 	const struct genl_small_ops *small_ops;
69 	const struct genl_multicast_group *mcgrps;
70 	struct module		*module;
71 };
72 
73 /**
74  * struct genl_info - receiving information
75  * @snd_seq: sending sequence number
76  * @snd_portid: netlink portid of sender
77  * @nlhdr: netlink message header
78  * @genlhdr: generic netlink message header
79  * @userhdr: user specific header
80  * @attrs: netlink attributes
81  * @_net: network namespace
82  * @user_ptr: user pointers
83  * @extack: extended ACK report struct
84  */
85 struct genl_info {
86 	u32			snd_seq;
87 	u32			snd_portid;
88 	struct nlmsghdr *	nlhdr;
89 	struct genlmsghdr *	genlhdr;
90 	void *			userhdr;
91 	struct nlattr **	attrs;
92 	possible_net_t		_net;
93 	void *			user_ptr[2];
94 	struct netlink_ext_ack *extack;
95 };
96 
genl_info_net(struct genl_info * info)97 static inline struct net *genl_info_net(struct genl_info *info)
98 {
99 	return read_pnet(&info->_net);
100 }
101 
genl_info_net_set(struct genl_info * info,struct net * net)102 static inline void genl_info_net_set(struct genl_info *info, struct net *net)
103 {
104 	write_pnet(&info->_net, net);
105 }
106 
107 #define GENL_SET_ERR_MSG(info, msg) NL_SET_ERR_MSG((info)->extack, msg)
108 
109 enum genl_validate_flags {
110 	GENL_DONT_VALIDATE_STRICT		= BIT(0),
111 	GENL_DONT_VALIDATE_DUMP			= BIT(1),
112 	GENL_DONT_VALIDATE_DUMP_STRICT		= BIT(2),
113 };
114 
115 /**
116  * struct genl_small_ops - generic netlink operations (small version)
117  * @cmd: command identifier
118  * @internal_flags: flags used by the family
119  * @flags: flags
120  * @validate: validation flags from enum genl_validate_flags
121  * @doit: standard command callback
122  * @dumpit: callback for dumpers
123  *
124  * This is a cut-down version of struct genl_ops for users who don't need
125  * most of the ancillary infra and want to save space.
126  */
127 struct genl_small_ops {
128 	int	(*doit)(struct sk_buff *skb, struct genl_info *info);
129 	int	(*dumpit)(struct sk_buff *skb, struct netlink_callback *cb);
130 	u8	cmd;
131 	u8	internal_flags;
132 	u8	flags;
133 	u8	validate;
134 };
135 
136 /**
137  * struct genl_ops - generic netlink operations
138  * @cmd: command identifier
139  * @internal_flags: flags used by the family
140  * @flags: flags
141  * @maxattr: maximum number of attributes supported
142  * @policy: netlink policy (takes precedence over family policy)
143  * @validate: validation flags from enum genl_validate_flags
144  * @doit: standard command callback
145  * @start: start callback for dumps
146  * @dumpit: callback for dumpers
147  * @done: completion callback for dumps
148  */
149 struct genl_ops {
150 	int		       (*doit)(struct sk_buff *skb,
151 				       struct genl_info *info);
152 	int		       (*start)(struct netlink_callback *cb);
153 	int		       (*dumpit)(struct sk_buff *skb,
154 					 struct netlink_callback *cb);
155 	int		       (*done)(struct netlink_callback *cb);
156 	const struct nla_policy *policy;
157 	unsigned int		maxattr;
158 	u8			cmd;
159 	u8			internal_flags;
160 	u8			flags;
161 	u8			validate;
162 };
163 
164 /**
165  * struct genl_info - info that is available during dumpit op call
166  * @family: generic netlink family - for internal genl code usage
167  * @ops: generic netlink ops - for internal genl code usage
168  * @attrs: netlink attributes
169  */
170 struct genl_dumpit_info {
171 	const struct genl_family *family;
172 	struct genl_ops op;
173 	struct nlattr **attrs;
174 };
175 
176 static inline const struct genl_dumpit_info *
genl_dumpit_info(struct netlink_callback * cb)177 genl_dumpit_info(struct netlink_callback *cb)
178 {
179 	return cb->data;
180 }
181 
182 int genl_register_family(struct genl_family *family);
183 int genl_unregister_family(const struct genl_family *family);
184 void genl_notify(const struct genl_family *family, struct sk_buff *skb,
185 		 struct genl_info *info, u32 group, gfp_t flags);
186 
187 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
188 		  const struct genl_family *family, int flags, u8 cmd);
189 
190 /**
191  * genlmsg_nlhdr - Obtain netlink header from user specified header
192  * @user_hdr: user header as returned from genlmsg_put()
193  *
194  * Returns pointer to netlink header.
195  */
genlmsg_nlhdr(void * user_hdr)196 static inline struct nlmsghdr *genlmsg_nlhdr(void *user_hdr)
197 {
198 	return (struct nlmsghdr *)((char *)user_hdr -
199 				   GENL_HDRLEN -
200 				   NLMSG_HDRLEN);
201 }
202 
203 /**
204  * genlmsg_parse_deprecated - parse attributes of a genetlink message
205  * @nlh: netlink message header
206  * @family: genetlink message family
207  * @tb: destination array with maxtype+1 elements
208  * @maxtype: maximum attribute type to be expected
209  * @policy: validation policy
210  * @extack: extended ACK report struct
211  */
genlmsg_parse_deprecated(const struct nlmsghdr * nlh,const struct genl_family * family,struct nlattr * tb[],int maxtype,const struct nla_policy * policy,struct netlink_ext_ack * extack)212 static inline int genlmsg_parse_deprecated(const struct nlmsghdr *nlh,
213 					   const struct genl_family *family,
214 					   struct nlattr *tb[], int maxtype,
215 					   const struct nla_policy *policy,
216 					   struct netlink_ext_ack *extack)
217 {
218 	return __nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype,
219 			     policy, NL_VALIDATE_LIBERAL, extack);
220 }
221 
222 /**
223  * genlmsg_parse - parse attributes of a genetlink message
224  * @nlh: netlink message header
225  * @family: genetlink message family
226  * @tb: destination array with maxtype+1 elements
227  * @maxtype: maximum attribute type to be expected
228  * @policy: validation policy
229  * @extack: extended ACK report struct
230  */
genlmsg_parse(const struct nlmsghdr * nlh,const struct genl_family * family,struct nlattr * tb[],int maxtype,const struct nla_policy * policy,struct netlink_ext_ack * extack)231 static inline int genlmsg_parse(const struct nlmsghdr *nlh,
232 				const struct genl_family *family,
233 				struct nlattr *tb[], int maxtype,
234 				const struct nla_policy *policy,
235 				struct netlink_ext_ack *extack)
236 {
237 	return __nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype,
238 			     policy, NL_VALIDATE_STRICT, extack);
239 }
240 
241 /**
242  * genl_dump_check_consistent - check if sequence is consistent and advertise if not
243  * @cb: netlink callback structure that stores the sequence number
244  * @user_hdr: user header as returned from genlmsg_put()
245  *
246  * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it
247  * simpler to use with generic netlink.
248  */
genl_dump_check_consistent(struct netlink_callback * cb,void * user_hdr)249 static inline void genl_dump_check_consistent(struct netlink_callback *cb,
250 					      void *user_hdr)
251 {
252 	nl_dump_check_consistent(cb, genlmsg_nlhdr(user_hdr));
253 }
254 
255 /**
256  * genlmsg_put_reply - Add generic netlink header to a reply message
257  * @skb: socket buffer holding the message
258  * @info: receiver info
259  * @family: generic netlink family
260  * @flags: netlink message flags
261  * @cmd: generic netlink command
262  *
263  * Returns pointer to user specific header
264  */
genlmsg_put_reply(struct sk_buff * skb,struct genl_info * info,const struct genl_family * family,int flags,u8 cmd)265 static inline void *genlmsg_put_reply(struct sk_buff *skb,
266 				      struct genl_info *info,
267 				      const struct genl_family *family,
268 				      int flags, u8 cmd)
269 {
270 	return genlmsg_put(skb, info->snd_portid, info->snd_seq, family,
271 			   flags, cmd);
272 }
273 
274 /**
275  * genlmsg_end - Finalize a generic netlink message
276  * @skb: socket buffer the message is stored in
277  * @hdr: user specific header
278  */
genlmsg_end(struct sk_buff * skb,void * hdr)279 static inline void genlmsg_end(struct sk_buff *skb, void *hdr)
280 {
281 	nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
282 }
283 
284 /**
285  * genlmsg_cancel - Cancel construction of a generic netlink message
286  * @skb: socket buffer the message is stored in
287  * @hdr: generic netlink message header
288  */
genlmsg_cancel(struct sk_buff * skb,void * hdr)289 static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr)
290 {
291 	if (hdr)
292 		nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
293 }
294 
295 /**
296  * genlmsg_multicast_netns - multicast a netlink message to a specific netns
297  * @family: the generic netlink family
298  * @net: the net namespace
299  * @skb: netlink message as socket buffer
300  * @portid: own netlink portid to avoid sending to yourself
301  * @group: offset of multicast group in groups array
302  * @flags: allocation flags
303  */
genlmsg_multicast_netns(const struct genl_family * family,struct net * net,struct sk_buff * skb,u32 portid,unsigned int group,gfp_t flags)304 static inline int genlmsg_multicast_netns(const struct genl_family *family,
305 					  struct net *net, struct sk_buff *skb,
306 					  u32 portid, unsigned int group, gfp_t flags)
307 {
308 	if (WARN_ON_ONCE(group >= family->n_mcgrps))
309 		return -EINVAL;
310 	group = family->mcgrp_offset + group;
311 	return nlmsg_multicast(net->genl_sock, skb, portid, group, flags);
312 }
313 
314 /**
315  * genlmsg_multicast - multicast a netlink message to the default netns
316  * @family: the generic netlink family
317  * @skb: netlink message as socket buffer
318  * @portid: own netlink portid to avoid sending to yourself
319  * @group: offset of multicast group in groups array
320  * @flags: allocation flags
321  */
genlmsg_multicast(const struct genl_family * family,struct sk_buff * skb,u32 portid,unsigned int group,gfp_t flags)322 static inline int genlmsg_multicast(const struct genl_family *family,
323 				    struct sk_buff *skb, u32 portid,
324 				    unsigned int group, gfp_t flags)
325 {
326 	return genlmsg_multicast_netns(family, &init_net, skb,
327 				       portid, group, flags);
328 }
329 
330 /**
331  * genlmsg_multicast_allns - multicast a netlink message to all net namespaces
332  * @family: the generic netlink family
333  * @skb: netlink message as socket buffer
334  * @portid: own netlink portid to avoid sending to yourself
335  * @group: offset of multicast group in groups array
336  * @flags: allocation flags
337  *
338  * This function must hold the RTNL or rcu_read_lock().
339  */
340 int genlmsg_multicast_allns(const struct genl_family *family,
341 			    struct sk_buff *skb, u32 portid,
342 			    unsigned int group, gfp_t flags);
343 
344 /**
345  * genlmsg_unicast - unicast a netlink message
346  * @skb: netlink message as socket buffer
347  * @portid: netlink portid of the destination socket
348  */
genlmsg_unicast(struct net * net,struct sk_buff * skb,u32 portid)349 static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid)
350 {
351 	return nlmsg_unicast(net->genl_sock, skb, portid);
352 }
353 
354 /**
355  * genlmsg_reply - reply to a request
356  * @skb: netlink message to be sent back
357  * @info: receiver information
358  */
genlmsg_reply(struct sk_buff * skb,struct genl_info * info)359 static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info)
360 {
361 	return genlmsg_unicast(genl_info_net(info), skb, info->snd_portid);
362 }
363 
364 /**
365  * gennlmsg_data - head of message payload
366  * @gnlh: genetlink message header
367  */
genlmsg_data(const struct genlmsghdr * gnlh)368 static inline void *genlmsg_data(const struct genlmsghdr *gnlh)
369 {
370 	return ((unsigned char *) gnlh + GENL_HDRLEN);
371 }
372 
373 /**
374  * genlmsg_len - length of message payload
375  * @gnlh: genetlink message header
376  */
genlmsg_len(const struct genlmsghdr * gnlh)377 static inline int genlmsg_len(const struct genlmsghdr *gnlh)
378 {
379 	struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh -
380 							NLMSG_HDRLEN);
381 	return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
382 }
383 
384 /**
385  * genlmsg_msg_size - length of genetlink message not including padding
386  * @payload: length of message payload
387  */
genlmsg_msg_size(int payload)388 static inline int genlmsg_msg_size(int payload)
389 {
390 	return GENL_HDRLEN + payload;
391 }
392 
393 /**
394  * genlmsg_total_size - length of genetlink message including padding
395  * @payload: length of message payload
396  */
genlmsg_total_size(int payload)397 static inline int genlmsg_total_size(int payload)
398 {
399 	return NLMSG_ALIGN(genlmsg_msg_size(payload));
400 }
401 
402 /**
403  * genlmsg_new - Allocate a new generic netlink message
404  * @payload: size of the message payload
405  * @flags: the type of memory to allocate.
406  */
genlmsg_new(size_t payload,gfp_t flags)407 static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
408 {
409 	return nlmsg_new(genlmsg_total_size(payload), flags);
410 }
411 
412 /**
413  * genl_set_err - report error to genetlink broadcast listeners
414  * @family: the generic netlink family
415  * @net: the network namespace to report the error to
416  * @portid: the PORTID of a process that we want to skip (if any)
417  * @group: the broadcast group that will notice the error
418  * 	(this is the offset of the multicast group in the groups array)
419  * @code: error code, must be negative (as usual in kernelspace)
420  *
421  * This function returns the number of broadcast listeners that have set the
422  * NETLINK_RECV_NO_ENOBUFS socket option.
423  */
genl_set_err(const struct genl_family * family,struct net * net,u32 portid,u32 group,int code)424 static inline int genl_set_err(const struct genl_family *family,
425 			       struct net *net, u32 portid,
426 			       u32 group, int code)
427 {
428 	if (WARN_ON_ONCE(group >= family->n_mcgrps))
429 		return -EINVAL;
430 	group = family->mcgrp_offset + group;
431 	return netlink_set_err(net->genl_sock, portid, group, code);
432 }
433 
genl_has_listeners(const struct genl_family * family,struct net * net,unsigned int group)434 static inline int genl_has_listeners(const struct genl_family *family,
435 				     struct net *net, unsigned int group)
436 {
437 	if (WARN_ON_ONCE(group >= family->n_mcgrps))
438 		return -EINVAL;
439 	group = family->mcgrp_offset + group;
440 	return netlink_has_listeners(net->genl_sock, group);
441 }
442 #endif	/* __NET_GENERIC_NETLINK_H */
443