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 * @flags: GENL_* flags (%GENL_ADMIN_PERM or %GENL_UNS_ADMIN_PERM)
15 */
16struct genl_multicast_group {
17 char name[GENL_NAMSIZ];
18 u8 flags;
19};
20
21struct genl_split_ops;
22struct genl_info;
23
24/**
25 * struct genl_family - generic netlink family
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 * @module: pointer to the owning module (set to THIS_MODULE)
40 * @mcgrps: multicast groups used by this family
41 * @n_mcgrps: number of multicast groups
42 * @resv_start_op: first operation for which reserved fields of the header
43 * can be validated and policies are required (see below);
44 * new families should leave this field at zero
45 * @ops: the operations supported by this family
46 * @n_ops: number of operations supported by this family
47 * @small_ops: the small-struct operations supported by this family
48 * @n_small_ops: number of small-struct operations supported by this family
49 * @split_ops: the split do/dump form of operation definition
50 * @n_split_ops: number of entries in @split_ops, not that with split do/dump
51 * ops the number of entries is not the same as number of commands
52 *
53 * Attribute policies (the combination of @policy and @maxattr fields)
54 * can be attached at the family level or at the operation level.
55 * If both are present the per-operation policy takes precedence.
56 * For operations before @resv_start_op lack of policy means that the core
57 * will perform no attribute parsing or validation. For newer operations
58 * if policy is not provided core will reject all TLV attributes.
59 */
60struct genl_family {
61 unsigned int hdrsize;
62 char name[GENL_NAMSIZ];
63 unsigned int version;
64 unsigned int maxattr;
65 u8 netnsok:1;
66 u8 parallel_ops:1;
67 u8 n_ops;
68 u8 n_small_ops;
69 u8 n_split_ops;
70 u8 n_mcgrps;
71 u8 resv_start_op;
72 const struct nla_policy *policy;
73 int (*pre_doit)(const struct genl_split_ops *ops,
74 struct sk_buff *skb,
75 struct genl_info *info);
76 void (*post_doit)(const struct genl_split_ops *ops,
77 struct sk_buff *skb,
78 struct genl_info *info);
79 const struct genl_ops * ops;
80 const struct genl_small_ops *small_ops;
81 const struct genl_split_ops *split_ops;
82 const struct genl_multicast_group *mcgrps;
83 struct module *module;
84
85/* private: internal use only */
86 /* protocol family identifier */
87 int id;
88 /* starting number of multicast group IDs in this family */
89 unsigned int mcgrp_offset;
90};
91
92/**
93 * struct genl_info - receiving information
94 * @snd_seq: sending sequence number
95 * @snd_portid: netlink portid of sender
96 * @family: generic netlink family
97 * @nlhdr: netlink message header
98 * @genlhdr: generic netlink message header
99 * @attrs: netlink attributes
100 * @_net: network namespace
101 * @user_ptr: user pointers
102 * @extack: extended ACK report struct
103 */
104struct genl_info {
105 u32 snd_seq;
106 u32 snd_portid;
107 const struct genl_family *family;
108 const struct nlmsghdr * nlhdr;
109 struct genlmsghdr * genlhdr;
110 struct nlattr ** attrs;
111 possible_net_t _net;
112 void * user_ptr[2];
113 struct netlink_ext_ack *extack;
114};
115
116static inline struct net *genl_info_net(const struct genl_info *info)
117{
118 return read_pnet(pnet: &info->_net);
119}
120
121static inline void genl_info_net_set(struct genl_info *info, struct net *net)
122{
123 write_pnet(pnet: &info->_net, net);
124}
125
126static inline void *genl_info_userhdr(const struct genl_info *info)
127{
128 return (u8 *)info->genlhdr + GENL_HDRLEN;
129}
130
131#define GENL_SET_ERR_MSG(info, msg) NL_SET_ERR_MSG((info)->extack, msg)
132
133#define GENL_SET_ERR_MSG_FMT(info, msg, args...) \
134 NL_SET_ERR_MSG_FMT((info)->extack, msg, ##args)
135
136/* Report that a root attribute is missing */
137#define GENL_REQ_ATTR_CHECK(info, attr) ({ \
138 struct genl_info *__info = (info); \
139 \
140 NL_REQ_ATTR_CHECK(__info->extack, NULL, __info->attrs, (attr)); \
141})
142
143enum genl_validate_flags {
144 GENL_DONT_VALIDATE_STRICT = BIT(0),
145 GENL_DONT_VALIDATE_DUMP = BIT(1),
146 GENL_DONT_VALIDATE_DUMP_STRICT = BIT(2),
147};
148
149/**
150 * struct genl_small_ops - generic netlink operations (small version)
151 * @cmd: command identifier
152 * @internal_flags: flags used by the family
153 * @flags: GENL_* flags (%GENL_ADMIN_PERM or %GENL_UNS_ADMIN_PERM)
154 * @validate: validation flags from enum genl_validate_flags
155 * @doit: standard command callback
156 * @dumpit: callback for dumpers
157 *
158 * This is a cut-down version of struct genl_ops for users who don't need
159 * most of the ancillary infra and want to save space.
160 */
161struct genl_small_ops {
162 int (*doit)(struct sk_buff *skb, struct genl_info *info);
163 int (*dumpit)(struct sk_buff *skb, struct netlink_callback *cb);
164 u8 cmd;
165 u8 internal_flags;
166 u8 flags;
167 u8 validate;
168};
169
170/**
171 * struct genl_ops - generic netlink operations
172 * @cmd: command identifier
173 * @internal_flags: flags used by the family
174 * @flags: GENL_* flags (%GENL_ADMIN_PERM or %GENL_UNS_ADMIN_PERM)
175 * @maxattr: maximum number of attributes supported
176 * @policy: netlink policy (takes precedence over family policy)
177 * @validate: validation flags from enum genl_validate_flags
178 * @doit: standard command callback
179 * @start: start callback for dumps
180 * @dumpit: callback for dumpers
181 * @done: completion callback for dumps
182 */
183struct genl_ops {
184 int (*doit)(struct sk_buff *skb,
185 struct genl_info *info);
186 int (*start)(struct netlink_callback *cb);
187 int (*dumpit)(struct sk_buff *skb,
188 struct netlink_callback *cb);
189 int (*done)(struct netlink_callback *cb);
190 const struct nla_policy *policy;
191 unsigned int maxattr;
192 u8 cmd;
193 u8 internal_flags;
194 u8 flags;
195 u8 validate;
196};
197
198/**
199 * struct genl_split_ops - generic netlink operations (do/dump split version)
200 * @cmd: command identifier
201 * @internal_flags: flags used by the family
202 * @flags: GENL_* flags (%GENL_ADMIN_PERM or %GENL_UNS_ADMIN_PERM)
203 * @validate: validation flags from enum genl_validate_flags
204 * @policy: netlink policy (takes precedence over family policy)
205 * @maxattr: maximum number of attributes supported
206 *
207 * Do callbacks:
208 * @pre_doit: called before an operation's @doit callback, it may
209 * do additional, common, filtering and return an error
210 * @doit: standard command callback
211 * @post_doit: called after an operation's @doit callback, it may
212 * undo operations done by pre_doit, for example release locks
213 *
214 * Dump callbacks:
215 * @start: start callback for dumps
216 * @dumpit: callback for dumpers
217 * @done: completion callback for dumps
218 *
219 * Do callbacks can be used if %GENL_CMD_CAP_DO is set in @flags.
220 * Dump callbacks can be used if %GENL_CMD_CAP_DUMP is set in @flags.
221 * Exactly one of those flags must be set.
222 */
223struct genl_split_ops {
224 union {
225 struct {
226 int (*pre_doit)(const struct genl_split_ops *ops,
227 struct sk_buff *skb,
228 struct genl_info *info);
229 int (*doit)(struct sk_buff *skb,
230 struct genl_info *info);
231 void (*post_doit)(const struct genl_split_ops *ops,
232 struct sk_buff *skb,
233 struct genl_info *info);
234 };
235 struct {
236 int (*start)(struct netlink_callback *cb);
237 int (*dumpit)(struct sk_buff *skb,
238 struct netlink_callback *cb);
239 int (*done)(struct netlink_callback *cb);
240 };
241 };
242 const struct nla_policy *policy;
243 unsigned int maxattr;
244 u8 cmd;
245 u8 internal_flags;
246 u8 flags;
247 u8 validate;
248};
249
250/**
251 * struct genl_dumpit_info - info that is available during dumpit op call
252 * @op: generic netlink ops - for internal genl code usage
253 * @attrs: netlink attributes
254 * @info: struct genl_info describing the request
255 */
256struct genl_dumpit_info {
257 struct genl_split_ops op;
258 struct genl_info info;
259};
260
261static inline const struct genl_dumpit_info *
262genl_dumpit_info(struct netlink_callback *cb)
263{
264 return cb->data;
265}
266
267static inline const struct genl_info *
268genl_info_dump(struct netlink_callback *cb)
269{
270 return &genl_dumpit_info(cb)->info;
271}
272
273/**
274 * genl_info_init_ntf() - initialize genl_info for notifications
275 * @info: genl_info struct to set up
276 * @family: pointer to the genetlink family
277 * @cmd: command to be used in the notification
278 *
279 * Initialize a locally declared struct genl_info to pass to various APIs.
280 * Intended to be used when creating notifications.
281 */
282static inline void
283genl_info_init_ntf(struct genl_info *info, const struct genl_family *family,
284 u8 cmd)
285{
286 struct genlmsghdr *hdr = (void *) &info->user_ptr[0];
287
288 memset(info, 0, sizeof(*info));
289 info->family = family;
290 info->genlhdr = hdr;
291 hdr->cmd = cmd;
292}
293
294static inline bool genl_info_is_ntf(const struct genl_info *info)
295{
296 return !info->nlhdr;
297}
298
299int genl_register_family(struct genl_family *family);
300int genl_unregister_family(const struct genl_family *family);
301void genl_notify(const struct genl_family *family, struct sk_buff *skb,
302 struct genl_info *info, u32 group, gfp_t flags);
303
304void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
305 const struct genl_family *family, int flags, u8 cmd);
306
307static inline void *
308__genlmsg_iput(struct sk_buff *skb, const struct genl_info *info, int flags)
309{
310 return genlmsg_put(skb, portid: info->snd_portid, seq: info->snd_seq, family: info->family,
311 flags, cmd: info->genlhdr->cmd);
312}
313
314/**
315 * genlmsg_iput - start genetlink message based on genl_info
316 * @skb: skb in which message header will be placed
317 * @info: genl_info as provided to do/dump handlers
318 *
319 * Convenience wrapper which starts a genetlink message based on
320 * information in user request. @info should be either the struct passed
321 * by genetlink core to do/dump handlers (when constructing replies to
322 * such requests) or a struct initialized by genl_info_init_ntf()
323 * when constructing notifications.
324 *
325 * Returns pointer to new genetlink header.
326 */
327static inline void *
328genlmsg_iput(struct sk_buff *skb, const struct genl_info *info)
329{
330 return __genlmsg_iput(skb, info, flags: 0);
331}
332
333/**
334 * genlmsg_nlhdr - Obtain netlink header from user specified header
335 * @user_hdr: user header as returned from genlmsg_put()
336 *
337 * Returns pointer to netlink header.
338 */
339static inline struct nlmsghdr *genlmsg_nlhdr(void *user_hdr)
340{
341 return (struct nlmsghdr *)((char *)user_hdr -
342 GENL_HDRLEN -
343 NLMSG_HDRLEN);
344}
345
346/**
347 * genlmsg_parse_deprecated - parse attributes of a genetlink message
348 * @nlh: netlink message header
349 * @family: genetlink message family
350 * @tb: destination array with maxtype+1 elements
351 * @maxtype: maximum attribute type to be expected
352 * @policy: validation policy
353 * @extack: extended ACK report struct
354 */
355static inline int genlmsg_parse_deprecated(const struct nlmsghdr *nlh,
356 const struct genl_family *family,
357 struct nlattr *tb[], int maxtype,
358 const struct nla_policy *policy,
359 struct netlink_ext_ack *extack)
360{
361 return __nlmsg_parse(nlh, hdrlen: family->hdrsize + GENL_HDRLEN, tb, maxtype,
362 policy, validate: NL_VALIDATE_LIBERAL, extack);
363}
364
365/**
366 * genlmsg_parse - parse attributes of a genetlink message
367 * @nlh: netlink message header
368 * @family: genetlink message family
369 * @tb: destination array with maxtype+1 elements
370 * @maxtype: maximum attribute type to be expected
371 * @policy: validation policy
372 * @extack: extended ACK report struct
373 */
374static inline int genlmsg_parse(const struct nlmsghdr *nlh,
375 const struct genl_family *family,
376 struct nlattr *tb[], int maxtype,
377 const struct nla_policy *policy,
378 struct netlink_ext_ack *extack)
379{
380 return __nlmsg_parse(nlh, hdrlen: family->hdrsize + GENL_HDRLEN, tb, maxtype,
381 policy, NL_VALIDATE_STRICT, extack);
382}
383
384/**
385 * genl_dump_check_consistent - check if sequence is consistent and advertise if not
386 * @cb: netlink callback structure that stores the sequence number
387 * @user_hdr: user header as returned from genlmsg_put()
388 *
389 * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it
390 * simpler to use with generic netlink.
391 */
392static inline void genl_dump_check_consistent(struct netlink_callback *cb,
393 void *user_hdr)
394{
395 nl_dump_check_consistent(cb, nlh: genlmsg_nlhdr(user_hdr));
396}
397
398/**
399 * genlmsg_put_reply - Add generic netlink header to a reply message
400 * @skb: socket buffer holding the message
401 * @info: receiver info
402 * @family: generic netlink family
403 * @flags: netlink message flags
404 * @cmd: generic netlink command
405 *
406 * Returns pointer to user specific header
407 */
408static inline void *genlmsg_put_reply(struct sk_buff *skb,
409 struct genl_info *info,
410 const struct genl_family *family,
411 int flags, u8 cmd)
412{
413 return genlmsg_put(skb, portid: info->snd_portid, seq: info->snd_seq, family,
414 flags, cmd);
415}
416
417/**
418 * genlmsg_end - Finalize a generic netlink message
419 * @skb: socket buffer the message is stored in
420 * @hdr: user specific header
421 */
422static inline void genlmsg_end(struct sk_buff *skb, void *hdr)
423{
424 nlmsg_end(skb, nlh: hdr - GENL_HDRLEN - NLMSG_HDRLEN);
425}
426
427/**
428 * genlmsg_cancel - Cancel construction of a generic netlink message
429 * @skb: socket buffer the message is stored in
430 * @hdr: generic netlink message header
431 */
432static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr)
433{
434 if (hdr)
435 nlmsg_cancel(skb, nlh: hdr - GENL_HDRLEN - NLMSG_HDRLEN);
436}
437
438/**
439 * genlmsg_multicast_netns - multicast a netlink message to a specific netns
440 * @family: the generic netlink family
441 * @net: the net namespace
442 * @skb: netlink message as socket buffer
443 * @portid: own netlink portid to avoid sending to yourself
444 * @group: offset of multicast group in groups array
445 * @flags: allocation flags
446 */
447static inline int genlmsg_multicast_netns(const struct genl_family *family,
448 struct net *net, struct sk_buff *skb,
449 u32 portid, unsigned int group, gfp_t flags)
450{
451 if (WARN_ON_ONCE(group >= family->n_mcgrps))
452 return -EINVAL;
453 group = family->mcgrp_offset + group;
454 return nlmsg_multicast(sk: net->genl_sock, skb, portid, group, flags);
455}
456
457/**
458 * genlmsg_multicast - multicast a netlink message to the default netns
459 * @family: the generic netlink family
460 * @skb: netlink message as socket buffer
461 * @portid: own netlink portid to avoid sending to yourself
462 * @group: offset of multicast group in groups array
463 * @flags: allocation flags
464 */
465static inline int genlmsg_multicast(const struct genl_family *family,
466 struct sk_buff *skb, u32 portid,
467 unsigned int group, gfp_t flags)
468{
469 return genlmsg_multicast_netns(family, net: &init_net, skb,
470 portid, group, flags);
471}
472
473/**
474 * genlmsg_multicast_allns - multicast a netlink message to all net namespaces
475 * @family: the generic netlink family
476 * @skb: netlink message as socket buffer
477 * @portid: own netlink portid to avoid sending to yourself
478 * @group: offset of multicast group in groups array
479 * @flags: allocation flags
480 *
481 * This function must hold the RTNL or rcu_read_lock().
482 */
483int genlmsg_multicast_allns(const struct genl_family *family,
484 struct sk_buff *skb, u32 portid,
485 unsigned int group, gfp_t flags);
486
487/**
488 * genlmsg_unicast - unicast a netlink message
489 * @net: network namespace to look up @portid in
490 * @skb: netlink message as socket buffer
491 * @portid: netlink portid of the destination socket
492 */
493static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid)
494{
495 return nlmsg_unicast(sk: net->genl_sock, skb, portid);
496}
497
498/**
499 * genlmsg_reply - reply to a request
500 * @skb: netlink message to be sent back
501 * @info: receiver information
502 */
503static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info)
504{
505 return genlmsg_unicast(net: genl_info_net(info), skb, portid: info->snd_portid);
506}
507
508/**
509 * genlmsg_data - head of message payload
510 * @gnlh: genetlink message header
511 */
512static inline void *genlmsg_data(const struct genlmsghdr *gnlh)
513{
514 return ((unsigned char *) gnlh + GENL_HDRLEN);
515}
516
517/**
518 * genlmsg_len - length of message payload
519 * @gnlh: genetlink message header
520 */
521static inline int genlmsg_len(const struct genlmsghdr *gnlh)
522{
523 struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh -
524 NLMSG_HDRLEN);
525 return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
526}
527
528/**
529 * genlmsg_msg_size - length of genetlink message not including padding
530 * @payload: length of message payload
531 */
532static inline int genlmsg_msg_size(int payload)
533{
534 return GENL_HDRLEN + payload;
535}
536
537/**
538 * genlmsg_total_size - length of genetlink message including padding
539 * @payload: length of message payload
540 */
541static inline int genlmsg_total_size(int payload)
542{
543 return NLMSG_ALIGN(genlmsg_msg_size(payload));
544}
545
546/**
547 * genlmsg_new - Allocate a new generic netlink message
548 * @payload: size of the message payload
549 * @flags: the type of memory to allocate.
550 */
551static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
552{
553 return nlmsg_new(payload: genlmsg_total_size(payload), flags);
554}
555
556/**
557 * genl_set_err - report error to genetlink broadcast listeners
558 * @family: the generic netlink family
559 * @net: the network namespace to report the error to
560 * @portid: the PORTID of a process that we want to skip (if any)
561 * @group: the broadcast group that will notice the error
562 * (this is the offset of the multicast group in the groups array)
563 * @code: error code, must be negative (as usual in kernelspace)
564 *
565 * This function returns the number of broadcast listeners that have set the
566 * NETLINK_RECV_NO_ENOBUFS socket option.
567 */
568static inline int genl_set_err(const struct genl_family *family,
569 struct net *net, u32 portid,
570 u32 group, int code)
571{
572 if (WARN_ON_ONCE(group >= family->n_mcgrps))
573 return -EINVAL;
574 group = family->mcgrp_offset + group;
575 return netlink_set_err(ssk: net->genl_sock, portid, group, code);
576}
577
578static inline int genl_has_listeners(const struct genl_family *family,
579 struct net *net, unsigned int group)
580{
581 if (WARN_ON_ONCE(group >= family->n_mcgrps))
582 return -EINVAL;
583 group = family->mcgrp_offset + group;
584 return netlink_has_listeners(sk: net->genl_sock, group);
585}
586#endif /* __NET_GENERIC_NETLINK_H */
587

source code of linux/include/net/genetlink.h