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 */
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
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 */
51struct 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
76struct 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 */
90struct 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
102static inline struct net *genl_info_net(struct genl_info *info)
103{
104 return read_pnet(&info->_net);
105}
106
107static 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
114static inline int genl_err_attr(struct genl_info *info, int err,
115 const 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 */
133struct 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
146int genl_register_family(struct genl_family *family);
147int genl_unregister_family(const struct genl_family *family);
148void genl_notify(const struct genl_family *family, struct sk_buff *skb,
149 struct genl_info *info, u32 group, gfp_t flags);
150
151void *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 *
158 * Returns pointer to netlink header.
159 */
160static inline struct nlmsghdr *genlmsg_nlhdr(void *user_hdr)
161{
162 return (struct nlmsghdr *)((char *)user_hdr -
163 GENL_HDRLEN -
164 NLMSG_HDRLEN);
165}
166
167/**
168 * genlmsg_parse - parse attributes of a genetlink message
169 * @nlh: netlink message header
170 * @family: genetlink message family
171 * @tb: destination array with maxtype+1 elements
172 * @maxtype: maximum attribute type to be expected
173 * @policy: validation policy
174 * @extack: extended ACK report struct
175 */
176static inline int genlmsg_parse(const struct nlmsghdr *nlh,
177 const struct genl_family *family,
178 struct nlattr *tb[], int maxtype,
179 const struct nla_policy *policy,
180 struct netlink_ext_ack *extack)
181{
182 return nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype,
183 policy, extack);
184}
185
186/**
187 * genl_dump_check_consistent - check if sequence is consistent and advertise if not
188 * @cb: netlink callback structure that stores the sequence number
189 * @user_hdr: user header as returned from genlmsg_put()
190 *
191 * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it
192 * simpler to use with generic netlink.
193 */
194static inline void genl_dump_check_consistent(struct netlink_callback *cb,
195 void *user_hdr)
196{
197 nl_dump_check_consistent(cb, genlmsg_nlhdr(user_hdr));
198}
199
200/**
201 * genlmsg_put_reply - Add generic netlink header to a reply message
202 * @skb: socket buffer holding the message
203 * @info: receiver info
204 * @family: generic netlink family
205 * @flags: netlink message flags
206 * @cmd: generic netlink command
207 *
208 * Returns pointer to user specific header
209 */
210static inline void *genlmsg_put_reply(struct sk_buff *skb,
211 struct genl_info *info,
212 const struct genl_family *family,
213 int flags, u8 cmd)
214{
215 return genlmsg_put(skb, info->snd_portid, info->snd_seq, family,
216 flags, cmd);
217}
218
219/**
220 * genlmsg_end - Finalize a generic netlink message
221 * @skb: socket buffer the message is stored in
222 * @hdr: user specific header
223 */
224static inline void genlmsg_end(struct sk_buff *skb, void *hdr)
225{
226 nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
227}
228
229/**
230 * genlmsg_cancel - Cancel construction of a generic netlink message
231 * @skb: socket buffer the message is stored in
232 * @hdr: generic netlink message header
233 */
234static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr)
235{
236 if (hdr)
237 nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
238}
239
240/**
241 * genlmsg_multicast_netns - multicast a netlink message to a specific netns
242 * @family: the generic netlink family
243 * @net: the net namespace
244 * @skb: netlink message as socket buffer
245 * @portid: own netlink portid to avoid sending to yourself
246 * @group: offset of multicast group in groups array
247 * @flags: allocation flags
248 */
249static inline int genlmsg_multicast_netns(const struct genl_family *family,
250 struct net *net, struct sk_buff *skb,
251 u32 portid, unsigned int group, gfp_t flags)
252{
253 if (WARN_ON_ONCE(group >= family->n_mcgrps))
254 return -EINVAL;
255 group = family->mcgrp_offset + group;
256 return nlmsg_multicast(net->genl_sock, skb, portid, group, flags);
257}
258
259/**
260 * genlmsg_multicast - multicast a netlink message to the default netns
261 * @family: the generic netlink family
262 * @skb: netlink message as socket buffer
263 * @portid: own netlink portid to avoid sending to yourself
264 * @group: offset of multicast group in groups array
265 * @flags: allocation flags
266 */
267static inline int genlmsg_multicast(const struct genl_family *family,
268 struct sk_buff *skb, u32 portid,
269 unsigned int group, gfp_t flags)
270{
271 return genlmsg_multicast_netns(family, &init_net, skb,
272 portid, group, flags);
273}
274
275/**
276 * genlmsg_multicast_allns - multicast a netlink message to all net namespaces
277 * @family: the generic netlink family
278 * @skb: netlink message as socket buffer
279 * @portid: own netlink portid to avoid sending to yourself
280 * @group: offset of multicast group in groups array
281 * @flags: allocation flags
282 *
283 * This function must hold the RTNL or rcu_read_lock().
284 */
285int genlmsg_multicast_allns(const struct genl_family *family,
286 struct sk_buff *skb, u32 portid,
287 unsigned int group, gfp_t flags);
288
289/**
290 * genlmsg_unicast - unicast a netlink message
291 * @skb: netlink message as socket buffer
292 * @portid: netlink portid of the destination socket
293 */
294static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid)
295{
296 return nlmsg_unicast(net->genl_sock, skb, portid);
297}
298
299/**
300 * genlmsg_reply - reply to a request
301 * @skb: netlink message to be sent back
302 * @info: receiver information
303 */
304static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info)
305{
306 return genlmsg_unicast(genl_info_net(info), skb, info->snd_portid);
307}
308
309/**
310 * gennlmsg_data - head of message payload
311 * @gnlh: genetlink message header
312 */
313static inline void *genlmsg_data(const struct genlmsghdr *gnlh)
314{
315 return ((unsigned char *) gnlh + GENL_HDRLEN);
316}
317
318/**
319 * genlmsg_len - length of message payload
320 * @gnlh: genetlink message header
321 */
322static inline int genlmsg_len(const struct genlmsghdr *gnlh)
323{
324 struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh -
325 NLMSG_HDRLEN);
326 return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
327}
328
329/**
330 * genlmsg_msg_size - length of genetlink message not including padding
331 * @payload: length of message payload
332 */
333static inline int genlmsg_msg_size(int payload)
334{
335 return GENL_HDRLEN + payload;
336}
337
338/**
339 * genlmsg_total_size - length of genetlink message including padding
340 * @payload: length of message payload
341 */
342static inline int genlmsg_total_size(int payload)
343{
344 return NLMSG_ALIGN(genlmsg_msg_size(payload));
345}
346
347/**
348 * genlmsg_new - Allocate a new generic netlink message
349 * @payload: size of the message payload
350 * @flags: the type of memory to allocate.
351 */
352static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
353{
354 return nlmsg_new(genlmsg_total_size(payload), flags);
355}
356
357/**
358 * genl_set_err - report error to genetlink broadcast listeners
359 * @family: the generic netlink family
360 * @net: the network namespace to report the error to
361 * @portid: the PORTID of a process that we want to skip (if any)
362 * @group: the broadcast group that will notice the error
363 * (this is the offset of the multicast group in the groups array)
364 * @code: error code, must be negative (as usual in kernelspace)
365 *
366 * This function returns the number of broadcast listeners that have set the
367 * NETLINK_RECV_NO_ENOBUFS socket option.
368 */
369static inline int genl_set_err(const struct genl_family *family,
370 struct net *net, u32 portid,
371 u32 group, int code)
372{
373 if (WARN_ON_ONCE(group >= family->n_mcgrps))
374 return -EINVAL;
375 group = family->mcgrp_offset + group;
376 return netlink_set_err(net->genl_sock, portid, group, code);
377}
378
379static inline int genl_has_listeners(const struct genl_family *family,
380 struct net *net, unsigned int group)
381{
382 if (WARN_ON_ONCE(group >= family->n_mcgrps))
383 return -EINVAL;
384 group = family->mcgrp_offset + group;
385 return netlink_has_listeners(net->genl_sock, group);
386}
387#endif /* __NET_GENERIC_NETLINK_H */
388