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