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Andrew Scullb4b6d4a2019-01-02 15:54:55 +00001/* 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 */
15struct genl_multicast_group {
16 char name[GENL_NAMSIZ];
17};
18
19struct genl_ops;
20struct 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
David Brazdil0f672f62019-12-10 10:32:29 +000029 * @policy: netlink policy
Andrew Scullb4b6d4a2019-01-02 15:54:55 +000030 * @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
Andrew Scullb4b6d4a2019-01-02 15:54:55 +000038 * @mcgrps: multicast groups used by this family
39 * @n_mcgrps: number of multicast groups
40 * @mcgrp_offset: starting number of multicast group IDs in this family
41 * (private)
42 * @ops: the operations supported by this family
43 * @n_ops: number of operations supported by this family
Olivier Deprez157378f2022-04-04 15:47:50 +020044 * @small_ops: the small-struct operations supported by this family
45 * @n_small_ops: number of small-struct operations supported by this family
Andrew Scullb4b6d4a2019-01-02 15:54:55 +000046 */
47struct genl_family {
48 int id; /* private */
49 unsigned int hdrsize;
50 char name[GENL_NAMSIZ];
51 unsigned int version;
52 unsigned int maxattr;
Olivier Deprez157378f2022-04-04 15:47:50 +020053 unsigned int mcgrp_offset; /* private */
54 u8 netnsok:1;
55 u8 parallel_ops:1;
56 u8 n_ops;
57 u8 n_small_ops;
58 u8 n_mcgrps;
David Brazdil0f672f62019-12-10 10:32:29 +000059 const struct nla_policy *policy;
Andrew Scullb4b6d4a2019-01-02 15:54:55 +000060 int (*pre_doit)(const struct genl_ops *ops,
61 struct sk_buff *skb,
62 struct genl_info *info);
63 void (*post_doit)(const struct genl_ops *ops,
64 struct sk_buff *skb,
65 struct genl_info *info);
Andrew Scullb4b6d4a2019-01-02 15:54:55 +000066 const struct genl_ops * ops;
Olivier Deprez157378f2022-04-04 15:47:50 +020067 const struct genl_small_ops *small_ops;
Andrew Scullb4b6d4a2019-01-02 15:54:55 +000068 const struct genl_multicast_group *mcgrps;
Andrew Scullb4b6d4a2019-01-02 15:54:55 +000069 struct module *module;
70};
71
Andrew Scullb4b6d4a2019-01-02 15:54:55 +000072/**
73 * struct genl_info - receiving information
74 * @snd_seq: sending sequence number
75 * @snd_portid: netlink portid of sender
76 * @nlhdr: netlink message header
77 * @genlhdr: generic netlink message header
78 * @userhdr: user specific header
79 * @attrs: netlink attributes
80 * @_net: network namespace
81 * @user_ptr: user pointers
82 * @extack: extended ACK report struct
83 */
84struct genl_info {
85 u32 snd_seq;
86 u32 snd_portid;
87 struct nlmsghdr * nlhdr;
88 struct genlmsghdr * genlhdr;
89 void * userhdr;
90 struct nlattr ** attrs;
91 possible_net_t _net;
92 void * user_ptr[2];
93 struct netlink_ext_ack *extack;
94};
95
96static inline struct net *genl_info_net(struct genl_info *info)
97{
98 return read_pnet(&info->_net);
99}
100
101static inline void genl_info_net_set(struct genl_info *info, struct net *net)
102{
103 write_pnet(&info->_net, net);
104}
105
106#define GENL_SET_ERR_MSG(info, msg) NL_SET_ERR_MSG((info)->extack, msg)
107
David Brazdil0f672f62019-12-10 10:32:29 +0000108enum genl_validate_flags {
109 GENL_DONT_VALIDATE_STRICT = BIT(0),
110 GENL_DONT_VALIDATE_DUMP = BIT(1),
111 GENL_DONT_VALIDATE_DUMP_STRICT = BIT(2),
112};
113
Andrew Scullb4b6d4a2019-01-02 15:54:55 +0000114/**
Olivier Deprez157378f2022-04-04 15:47:50 +0200115 * struct genl_small_ops - generic netlink operations (small version)
116 * @cmd: command identifier
117 * @internal_flags: flags used by the family
118 * @flags: flags
119 * @validate: validation flags from enum genl_validate_flags
120 * @doit: standard command callback
121 * @dumpit: callback for dumpers
122 *
123 * This is a cut-down version of struct genl_ops for users who don't need
124 * most of the ancillary infra and want to save space.
125 */
126struct genl_small_ops {
127 int (*doit)(struct sk_buff *skb, struct genl_info *info);
128 int (*dumpit)(struct sk_buff *skb, struct netlink_callback *cb);
129 u8 cmd;
130 u8 internal_flags;
131 u8 flags;
132 u8 validate;
133};
134
135/**
Andrew Scullb4b6d4a2019-01-02 15:54:55 +0000136 * struct genl_ops - generic netlink operations
137 * @cmd: command identifier
138 * @internal_flags: flags used by the family
139 * @flags: flags
Olivier Deprez157378f2022-04-04 15:47:50 +0200140 * @maxattr: maximum number of attributes supported
141 * @policy: netlink policy (takes precedence over family policy)
142 * @validate: validation flags from enum genl_validate_flags
Andrew Scullb4b6d4a2019-01-02 15:54:55 +0000143 * @doit: standard command callback
144 * @start: start callback for dumps
145 * @dumpit: callback for dumpers
146 * @done: completion callback for dumps
147 */
148struct genl_ops {
Andrew Scullb4b6d4a2019-01-02 15:54:55 +0000149 int (*doit)(struct sk_buff *skb,
150 struct genl_info *info);
151 int (*start)(struct netlink_callback *cb);
152 int (*dumpit)(struct sk_buff *skb,
153 struct netlink_callback *cb);
154 int (*done)(struct netlink_callback *cb);
Olivier Deprez157378f2022-04-04 15:47:50 +0200155 const struct nla_policy *policy;
156 unsigned int maxattr;
Andrew Scullb4b6d4a2019-01-02 15:54:55 +0000157 u8 cmd;
158 u8 internal_flags;
159 u8 flags;
David Brazdil0f672f62019-12-10 10:32:29 +0000160 u8 validate;
Andrew Scullb4b6d4a2019-01-02 15:54:55 +0000161};
162
Olivier Deprez157378f2022-04-04 15:47:50 +0200163/**
164 * struct genl_info - info that is available during dumpit op call
165 * @family: generic netlink family - for internal genl code usage
166 * @ops: generic netlink ops - for internal genl code usage
167 * @attrs: netlink attributes
168 */
169struct genl_dumpit_info {
170 const struct genl_family *family;
171 struct genl_ops op;
172 struct nlattr **attrs;
173};
174
175static inline const struct genl_dumpit_info *
176genl_dumpit_info(struct netlink_callback *cb)
177{
178 return cb->data;
179}
180
Andrew Scullb4b6d4a2019-01-02 15:54:55 +0000181int genl_register_family(struct genl_family *family);
182int genl_unregister_family(const struct genl_family *family);
183void genl_notify(const struct genl_family *family, struct sk_buff *skb,
184 struct genl_info *info, u32 group, gfp_t flags);
185
186void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
187 const struct genl_family *family, int flags, u8 cmd);
188
189/**
190 * genlmsg_nlhdr - Obtain netlink header from user specified header
191 * @user_hdr: user header as returned from genlmsg_put()
192 *
193 * Returns pointer to netlink header.
194 */
195static inline struct nlmsghdr *genlmsg_nlhdr(void *user_hdr)
196{
197 return (struct nlmsghdr *)((char *)user_hdr -
198 GENL_HDRLEN -
199 NLMSG_HDRLEN);
200}
201
202/**
David Brazdil0f672f62019-12-10 10:32:29 +0000203 * genlmsg_parse_deprecated - parse attributes of a genetlink message
204 * @nlh: netlink message header
205 * @family: genetlink message family
206 * @tb: destination array with maxtype+1 elements
207 * @maxtype: maximum attribute type to be expected
208 * @policy: validation policy
209 * @extack: extended ACK report struct
210 */
211static inline int genlmsg_parse_deprecated(const struct nlmsghdr *nlh,
212 const struct genl_family *family,
213 struct nlattr *tb[], int maxtype,
214 const struct nla_policy *policy,
215 struct netlink_ext_ack *extack)
216{
217 return __nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype,
218 policy, NL_VALIDATE_LIBERAL, extack);
219}
220
221/**
Andrew Scullb4b6d4a2019-01-02 15:54:55 +0000222 * genlmsg_parse - parse attributes of a genetlink message
223 * @nlh: netlink message header
224 * @family: genetlink message family
225 * @tb: destination array with maxtype+1 elements
226 * @maxtype: maximum attribute type to be expected
227 * @policy: validation policy
228 * @extack: extended ACK report struct
229 */
230static inline int genlmsg_parse(const struct nlmsghdr *nlh,
231 const struct genl_family *family,
232 struct nlattr *tb[], int maxtype,
233 const struct nla_policy *policy,
234 struct netlink_ext_ack *extack)
235{
David Brazdil0f672f62019-12-10 10:32:29 +0000236 return __nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype,
237 policy, NL_VALIDATE_STRICT, extack);
Andrew Scullb4b6d4a2019-01-02 15:54:55 +0000238}
239
240/**
241 * genl_dump_check_consistent - check if sequence is consistent and advertise if not
242 * @cb: netlink callback structure that stores the sequence number
243 * @user_hdr: user header as returned from genlmsg_put()
244 *
245 * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it
246 * simpler to use with generic netlink.
247 */
248static inline void genl_dump_check_consistent(struct netlink_callback *cb,
249 void *user_hdr)
250{
251 nl_dump_check_consistent(cb, genlmsg_nlhdr(user_hdr));
252}
253
254/**
255 * genlmsg_put_reply - Add generic netlink header to a reply message
256 * @skb: socket buffer holding the message
257 * @info: receiver info
258 * @family: generic netlink family
259 * @flags: netlink message flags
260 * @cmd: generic netlink command
261 *
262 * Returns pointer to user specific header
263 */
264static inline void *genlmsg_put_reply(struct sk_buff *skb,
265 struct genl_info *info,
266 const struct genl_family *family,
267 int flags, u8 cmd)
268{
269 return genlmsg_put(skb, info->snd_portid, info->snd_seq, family,
270 flags, cmd);
271}
272
273/**
274 * genlmsg_end - Finalize a generic netlink message
275 * @skb: socket buffer the message is stored in
276 * @hdr: user specific header
277 */
278static inline void genlmsg_end(struct sk_buff *skb, void *hdr)
279{
280 nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
281}
282
283/**
284 * genlmsg_cancel - Cancel construction of a generic netlink message
285 * @skb: socket buffer the message is stored in
286 * @hdr: generic netlink message header
287 */
288static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr)
289{
290 if (hdr)
291 nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
292}
293
294/**
295 * genlmsg_multicast_netns - multicast a netlink message to a specific netns
296 * @family: the generic netlink family
297 * @net: the net namespace
298 * @skb: netlink message as socket buffer
299 * @portid: own netlink portid to avoid sending to yourself
300 * @group: offset of multicast group in groups array
301 * @flags: allocation flags
302 */
303static inline int genlmsg_multicast_netns(const struct genl_family *family,
304 struct net *net, struct sk_buff *skb,
305 u32 portid, unsigned int group, gfp_t flags)
306{
307 if (WARN_ON_ONCE(group >= family->n_mcgrps))
308 return -EINVAL;
309 group = family->mcgrp_offset + group;
310 return nlmsg_multicast(net->genl_sock, skb, portid, group, flags);
311}
312
313/**
314 * genlmsg_multicast - multicast a netlink message to the default netns
315 * @family: the generic netlink family
316 * @skb: netlink message as socket buffer
317 * @portid: own netlink portid to avoid sending to yourself
318 * @group: offset of multicast group in groups array
319 * @flags: allocation flags
320 */
321static inline int genlmsg_multicast(const struct genl_family *family,
322 struct sk_buff *skb, u32 portid,
323 unsigned int group, gfp_t flags)
324{
325 return genlmsg_multicast_netns(family, &init_net, skb,
326 portid, group, flags);
327}
328
329/**
330 * genlmsg_multicast_allns - multicast a netlink message to all net namespaces
331 * @family: the generic netlink family
332 * @skb: netlink message as socket buffer
333 * @portid: own netlink portid to avoid sending to yourself
334 * @group: offset of multicast group in groups array
335 * @flags: allocation flags
336 *
337 * This function must hold the RTNL or rcu_read_lock().
338 */
339int genlmsg_multicast_allns(const struct genl_family *family,
340 struct sk_buff *skb, u32 portid,
341 unsigned int group, gfp_t flags);
342
343/**
344 * genlmsg_unicast - unicast a netlink message
345 * @skb: netlink message as socket buffer
346 * @portid: netlink portid of the destination socket
347 */
348static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid)
349{
350 return nlmsg_unicast(net->genl_sock, skb, portid);
351}
352
353/**
354 * genlmsg_reply - reply to a request
355 * @skb: netlink message to be sent back
356 * @info: receiver information
357 */
358static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info)
359{
360 return genlmsg_unicast(genl_info_net(info), skb, info->snd_portid);
361}
362
363/**
364 * gennlmsg_data - head of message payload
365 * @gnlh: genetlink message header
366 */
367static inline void *genlmsg_data(const struct genlmsghdr *gnlh)
368{
369 return ((unsigned char *) gnlh + GENL_HDRLEN);
370}
371
372/**
373 * genlmsg_len - length of message payload
374 * @gnlh: genetlink message header
375 */
376static inline int genlmsg_len(const struct genlmsghdr *gnlh)
377{
378 struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh -
379 NLMSG_HDRLEN);
380 return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
381}
382
383/**
384 * genlmsg_msg_size - length of genetlink message not including padding
385 * @payload: length of message payload
386 */
387static inline int genlmsg_msg_size(int payload)
388{
389 return GENL_HDRLEN + payload;
390}
391
392/**
393 * genlmsg_total_size - length of genetlink message including padding
394 * @payload: length of message payload
395 */
396static inline int genlmsg_total_size(int payload)
397{
398 return NLMSG_ALIGN(genlmsg_msg_size(payload));
399}
400
401/**
402 * genlmsg_new - Allocate a new generic netlink message
403 * @payload: size of the message payload
404 * @flags: the type of memory to allocate.
405 */
406static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
407{
408 return nlmsg_new(genlmsg_total_size(payload), flags);
409}
410
411/**
412 * genl_set_err - report error to genetlink broadcast listeners
413 * @family: the generic netlink family
414 * @net: the network namespace to report the error to
415 * @portid: the PORTID of a process that we want to skip (if any)
416 * @group: the broadcast group that will notice the error
417 * (this is the offset of the multicast group in the groups array)
418 * @code: error code, must be negative (as usual in kernelspace)
419 *
420 * This function returns the number of broadcast listeners that have set the
421 * NETLINK_RECV_NO_ENOBUFS socket option.
422 */
423static inline int genl_set_err(const struct genl_family *family,
424 struct net *net, u32 portid,
425 u32 group, int code)
426{
427 if (WARN_ON_ONCE(group >= family->n_mcgrps))
428 return -EINVAL;
429 group = family->mcgrp_offset + group;
430 return netlink_set_err(net->genl_sock, portid, group, code);
431}
432
433static inline int genl_has_listeners(const struct genl_family *family,
434 struct net *net, unsigned int group)
435{
436 if (WARN_ON_ONCE(group >= family->n_mcgrps))
437 return -EINVAL;
438 group = family->mcgrp_offset + group;
439 return netlink_has_listeners(net->genl_sock, group);
440}
441#endif /* __NET_GENERIC_NETLINK_H */