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