1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __NET_GENERIC_NETLINK_H
3#define __NET_GENERIC_NETLINK_H
4
5#include <linux/net.h>
6#include <net/netlink.h>
7#include <net/net_namespace.h>
8#include <uapi/linux/genetlink.h>
9
10#define GENLMSG_DEFAULT_SIZE (NLMSG_DEFAULT_SIZE - GENL_HDRLEN)
11
12/* Non-parallel generic netlink requests are serialized by a global lock. */
13void genl_lock(void);
14void genl_unlock(void);
15
16#define MODULE_ALIAS_GENL_FAMILY(family) \
17 MODULE_ALIAS_NET_PF_PROTO_NAME(PF_NETLINK, NETLINK_GENERIC, "-family-" family)
18
19/* Binding to multicast group requires %CAP_NET_ADMIN */
20#define GENL_MCAST_CAP_NET_ADMIN BIT(0)
21/* Binding to multicast group requires %CAP_SYS_ADMIN */
22#define GENL_MCAST_CAP_SYS_ADMIN BIT(1)
23
24/**
25 * struct genl_multicast_group - generic netlink multicast group
26 * @name: name of the multicast group, names are per-family
27 * @flags: GENL_MCAST_* flags
28 */
29struct genl_multicast_group {
30 char name[GENL_NAMSIZ];
31 u8 flags;
32};
33
34struct genl_split_ops;
35struct genl_info;
36
37/**
38 * struct genl_family - generic netlink family
39 * @hdrsize: length of user specific header in bytes
40 * @name: name of family
41 * @version: protocol version
42 * @maxattr: maximum number of attributes supported
43 * @policy: netlink policy
44 * @netnsok: set to true if the family can handle network
45 * namespaces and should be presented in all of them
46 * @parallel_ops: operations can be called in parallel and aren't
47 * synchronized by the core genetlink code
48 * @pre_doit: called before an operation's doit callback, it may
49 * do additional, common, filtering and return an error
50 * @post_doit: called after an operation's doit callback, it may
51 * undo operations done by pre_doit, for example release locks
52 * @bind: called when family multicast group is added to a netlink socket
53 * @unbind: called when family multicast group is removed from a netlink socket
54 * @module: pointer to the owning module (set to THIS_MODULE)
55 * @mcgrps: multicast groups used by this family
56 * @n_mcgrps: number of multicast groups
57 * @resv_start_op: first operation for which reserved fields of the header
58 * can be validated and policies are required (see below);
59 * new families should leave this field at zero
60 * @ops: the operations supported by this family
61 * @n_ops: number of operations supported by this family
62 * @small_ops: the small-struct operations supported by this family
63 * @n_small_ops: number of small-struct operations supported by this family
64 * @split_ops: the split do/dump form of operation definition
65 * @n_split_ops: number of entries in @split_ops, note that with split do/dump
66 * ops the number of entries is not the same as number of commands
67 * @sock_priv_size: the size of per-socket private memory
68 * @sock_priv_init: the per-socket private memory initializer
69 * @sock_priv_destroy: the per-socket private memory destructor
70 *
71 * Attribute policies (the combination of @policy and @maxattr fields)
72 * can be attached at the family level or at the operation level.
73 * If both are present the per-operation policy takes precedence.
74 * For operations before @resv_start_op lack of policy means that the core
75 * will perform no attribute parsing or validation. For newer operations
76 * if policy is not provided core will reject all TLV attributes.
77 */
78struct genl_family {
79 unsigned int hdrsize;
80 char name[GENL_NAMSIZ];
81 unsigned int version;
82 unsigned int maxattr;
83 u8 netnsok:1;
84 u8 parallel_ops:1;
85 u8 n_ops;
86 u8 n_small_ops;
87 u8 n_split_ops;
88 u8 n_mcgrps;
89 u8 resv_start_op;
90 const struct nla_policy *policy;
91 int (*pre_doit)(const struct genl_split_ops *ops,
92 struct sk_buff *skb,
93 struct genl_info *info);
94 void (*post_doit)(const struct genl_split_ops *ops,
95 struct sk_buff *skb,
96 struct genl_info *info);
97 int (*bind)(int mcgrp);
98 void (*unbind)(int mcgrp);
99 const struct genl_ops * ops;
100 const struct genl_small_ops *small_ops;
101 const struct genl_split_ops *split_ops;
102 const struct genl_multicast_group *mcgrps;
103 struct module *module;
104
105 size_t sock_priv_size;
106 void (*sock_priv_init)(void *priv);
107 void (*sock_priv_destroy)(void *priv);
108
109/* private: internal use only */
110 /* protocol family identifier */
111 int id;
112 /* starting number of multicast group IDs in this family */
113 unsigned int mcgrp_offset;
114 /* list of per-socket privs */
115 struct xarray *sock_privs;
116};
117
118/**
119 * struct genl_info - receiving information
120 * @snd_seq: sending sequence number
121 * @snd_portid: netlink portid of sender
122 * @family: generic netlink family
123 * @nlhdr: netlink message header
124 * @genlhdr: generic netlink message header
125 * @attrs: netlink attributes
126 * @_net: network namespace
127 * @ctx: storage space for the use by the family
128 * @user_ptr: user pointers (deprecated, use ctx instead)
129 * @extack: extended ACK report struct
130 */
131struct genl_info {
132 u32 snd_seq;
133 u32 snd_portid;
134 const struct genl_family *family;
135 const struct nlmsghdr * nlhdr;
136 struct genlmsghdr * genlhdr;
137 struct nlattr ** attrs;
138 possible_net_t _net;
139 union {
140 u8 ctx[NETLINK_CTX_SIZE];
141 void * user_ptr[2];
142 };
143 struct netlink_ext_ack *extack;
144};
145
146static inline struct net *genl_info_net(const struct genl_info *info)
147{
148 return read_pnet(pnet: &info->_net);
149}
150
151static inline void genl_info_net_set(struct genl_info *info, struct net *net)
152{
153 write_pnet(pnet: &info->_net, net);
154}
155
156static inline void *genl_info_userhdr(const struct genl_info *info)
157{
158 return (u8 *)info->genlhdr + GENL_HDRLEN;
159}
160
161#define GENL_SET_ERR_MSG(info, msg) NL_SET_ERR_MSG((info)->extack, msg)
162
163#define GENL_SET_ERR_MSG_FMT(info, msg, args...) \
164 NL_SET_ERR_MSG_FMT((info)->extack, msg, ##args)
165
166/* Report that a root attribute is missing */
167#define GENL_REQ_ATTR_CHECK(info, attr) ({ \
168 const struct genl_info *__info = (info); \
169 \
170 NL_REQ_ATTR_CHECK(__info->extack, NULL, __info->attrs, (attr)); \
171})
172
173enum genl_validate_flags {
174 GENL_DONT_VALIDATE_STRICT = BIT(0),
175 GENL_DONT_VALIDATE_DUMP = BIT(1),
176 GENL_DONT_VALIDATE_DUMP_STRICT = BIT(2),
177};
178
179/**
180 * struct genl_small_ops - generic netlink operations (small version)
181 * @cmd: command identifier
182 * @internal_flags: flags used by the family
183 * @flags: GENL_* flags (%GENL_ADMIN_PERM or %GENL_UNS_ADMIN_PERM)
184 * @validate: validation flags from enum genl_validate_flags
185 * @doit: standard command callback
186 * @dumpit: callback for dumpers
187 *
188 * This is a cut-down version of struct genl_ops for users who don't need
189 * most of the ancillary infra and want to save space.
190 */
191struct genl_small_ops {
192 int (*doit)(struct sk_buff *skb, struct genl_info *info);
193 int (*dumpit)(struct sk_buff *skb, struct netlink_callback *cb);
194 u8 cmd;
195 u8 internal_flags;
196 u8 flags;
197 u8 validate;
198};
199
200/**
201 * struct genl_ops - generic netlink operations
202 * @cmd: command identifier
203 * @internal_flags: flags used by the family
204 * @flags: GENL_* flags (%GENL_ADMIN_PERM or %GENL_UNS_ADMIN_PERM)
205 * @maxattr: maximum number of attributes supported
206 * @policy: netlink policy (takes precedence over family policy)
207 * @validate: validation flags from enum genl_validate_flags
208 * @doit: standard command callback
209 * @start: start callback for dumps
210 * @dumpit: callback for dumpers
211 * @done: completion callback for dumps
212 */
213struct genl_ops {
214 int (*doit)(struct sk_buff *skb,
215 struct genl_info *info);
216 int (*start)(struct netlink_callback *cb);
217 int (*dumpit)(struct sk_buff *skb,
218 struct netlink_callback *cb);
219 int (*done)(struct netlink_callback *cb);
220 const struct nla_policy *policy;
221 unsigned int maxattr;
222 u8 cmd;
223 u8 internal_flags;
224 u8 flags;
225 u8 validate;
226};
227
228/**
229 * struct genl_split_ops - generic netlink operations (do/dump split version)
230 * @cmd: command identifier
231 * @internal_flags: flags used by the family
232 * @flags: GENL_* flags (%GENL_ADMIN_PERM or %GENL_UNS_ADMIN_PERM)
233 * @validate: validation flags from enum genl_validate_flags
234 * @policy: netlink policy (takes precedence over family policy)
235 * @maxattr: maximum number of attributes supported
236 *
237 * Do callbacks:
238 * @pre_doit: called before an operation's @doit callback, it may
239 * do additional, common, filtering and return an error
240 * @doit: standard command callback
241 * @post_doit: called after an operation's @doit callback, it may
242 * undo operations done by pre_doit, for example release locks
243 *
244 * Dump callbacks:
245 * @start: start callback for dumps
246 * @dumpit: callback for dumpers
247 * @done: completion callback for dumps
248 *
249 * Do callbacks can be used if %GENL_CMD_CAP_DO is set in @flags.
250 * Dump callbacks can be used if %GENL_CMD_CAP_DUMP is set in @flags.
251 * Exactly one of those flags must be set.
252 */
253struct genl_split_ops {
254 union {
255 struct {
256 int (*pre_doit)(const struct genl_split_ops *ops,
257 struct sk_buff *skb,
258 struct genl_info *info);
259 int (*doit)(struct sk_buff *skb,
260 struct genl_info *info);
261 void (*post_doit)(const struct genl_split_ops *ops,
262 struct sk_buff *skb,
263 struct genl_info *info);
264 };
265 struct {
266 int (*start)(struct netlink_callback *cb);
267 int (*dumpit)(struct sk_buff *skb,
268 struct netlink_callback *cb);
269 int (*done)(struct netlink_callback *cb);
270 };
271 };
272 const struct nla_policy *policy;
273 unsigned int maxattr;
274 u8 cmd;
275 u8 internal_flags;
276 u8 flags;
277 u8 validate;
278};
279
280/**
281 * struct genl_dumpit_info - info that is available during dumpit op call
282 * @op: generic netlink ops - for internal genl code usage
283 * @attrs: netlink attributes
284 * @info: struct genl_info describing the request
285 */
286struct genl_dumpit_info {
287 struct genl_split_ops op;
288 struct genl_info info;
289};
290
291static inline const struct genl_dumpit_info *
292genl_dumpit_info(struct netlink_callback *cb)
293{
294 return cb->data;
295}
296
297static inline const struct genl_info *
298genl_info_dump(struct netlink_callback *cb)
299{
300 return &genl_dumpit_info(cb)->info;
301}
302
303/**
304 * genl_info_init_ntf() - initialize genl_info for notifications
305 * @info: genl_info struct to set up
306 * @family: pointer to the genetlink family
307 * @cmd: command to be used in the notification
308 *
309 * Initialize a locally declared struct genl_info to pass to various APIs.
310 * Intended to be used when creating notifications.
311 */
312static inline void
313genl_info_init_ntf(struct genl_info *info, const struct genl_family *family,
314 u8 cmd)
315{
316 struct genlmsghdr *hdr = (void *) &info->user_ptr[0];
317
318 memset(info, 0, sizeof(*info));
319 info->family = family;
320 info->genlhdr = hdr;
321 hdr->cmd = cmd;
322}
323
324static inline bool genl_info_is_ntf(const struct genl_info *info)
325{
326 return !info->nlhdr;
327}
328
329void *__genl_sk_priv_get(struct genl_family *family, struct sock *sk);
330void *genl_sk_priv_get(struct genl_family *family, struct sock *sk);
331int genl_register_family(struct genl_family *family);
332int genl_unregister_family(const struct genl_family *family);
333void genl_notify(const struct genl_family *family, struct sk_buff *skb,
334 struct genl_info *info, u32 group, gfp_t flags);
335
336void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
337 const struct genl_family *family, int flags, u8 cmd);
338
339static inline void *
340__genlmsg_iput(struct sk_buff *skb, const struct genl_info *info, int flags)
341{
342 return genlmsg_put(skb, portid: info->snd_portid, seq: info->snd_seq, family: info->family,
343 flags, cmd: info->genlhdr->cmd);
344}
345
346/**
347 * genlmsg_iput - start genetlink message based on genl_info
348 * @skb: skb in which message header will be placed
349 * @info: genl_info as provided to do/dump handlers
350 *
351 * Convenience wrapper which starts a genetlink message based on
352 * information in user request. @info should be either the struct passed
353 * by genetlink core to do/dump handlers (when constructing replies to
354 * such requests) or a struct initialized by genl_info_init_ntf()
355 * when constructing notifications.
356 *
357 * Returns: pointer to new genetlink header.
358 */
359static inline void *
360genlmsg_iput(struct sk_buff *skb, const struct genl_info *info)
361{
362 return __genlmsg_iput(skb, info, flags: 0);
363}
364
365/**
366 * genlmsg_nlhdr - Obtain netlink header from user specified header
367 * @user_hdr: user header as returned from genlmsg_put()
368 *
369 * Returns: pointer to netlink header.
370 */
371static inline struct nlmsghdr *genlmsg_nlhdr(void *user_hdr)
372{
373 return (struct nlmsghdr *)((char *)user_hdr -
374 GENL_HDRLEN -
375 NLMSG_HDRLEN);
376}
377
378/**
379 * genlmsg_parse_deprecated - parse attributes of a genetlink message
380 * @nlh: netlink message header
381 * @family: genetlink message family
382 * @tb: destination array with maxtype+1 elements
383 * @maxtype: maximum attribute type to be expected
384 * @policy: validation policy
385 * @extack: extended ACK report struct
386 */
387static inline int genlmsg_parse_deprecated(const struct nlmsghdr *nlh,
388 const struct genl_family *family,
389 struct nlattr *tb[], int maxtype,
390 const struct nla_policy *policy,
391 struct netlink_ext_ack *extack)
392{
393 return __nlmsg_parse(nlh, hdrlen: family->hdrsize + GENL_HDRLEN, tb, maxtype,
394 policy, validate: NL_VALIDATE_LIBERAL, extack);
395}
396
397/**
398 * genlmsg_parse - parse attributes of a genetlink message
399 * @nlh: netlink message header
400 * @family: genetlink message family
401 * @tb: destination array with maxtype+1 elements
402 * @maxtype: maximum attribute type to be expected
403 * @policy: validation policy
404 * @extack: extended ACK report struct
405 */
406static inline int genlmsg_parse(const struct nlmsghdr *nlh,
407 const struct genl_family *family,
408 struct nlattr *tb[], int maxtype,
409 const struct nla_policy *policy,
410 struct netlink_ext_ack *extack)
411{
412 return __nlmsg_parse(nlh, hdrlen: family->hdrsize + GENL_HDRLEN, tb, maxtype,
413 policy, NL_VALIDATE_STRICT, extack);
414}
415
416/**
417 * genl_dump_check_consistent - check if sequence is consistent and advertise if not
418 * @cb: netlink callback structure that stores the sequence number
419 * @user_hdr: user header as returned from genlmsg_put()
420 *
421 * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it
422 * simpler to use with generic netlink.
423 */
424static inline void genl_dump_check_consistent(struct netlink_callback *cb,
425 void *user_hdr)
426{
427 nl_dump_check_consistent(cb, nlh: genlmsg_nlhdr(user_hdr));
428}
429
430/**
431 * genlmsg_put_reply - Add generic netlink header to a reply message
432 * @skb: socket buffer holding the message
433 * @info: receiver info
434 * @family: generic netlink family
435 * @flags: netlink message flags
436 * @cmd: generic netlink command
437 *
438 * Returns: pointer to user specific header
439 */
440static inline void *genlmsg_put_reply(struct sk_buff *skb,
441 struct genl_info *info,
442 const struct genl_family *family,
443 int flags, u8 cmd)
444{
445 return genlmsg_put(skb, portid: info->snd_portid, seq: info->snd_seq, family,
446 flags, cmd);
447}
448
449/**
450 * genlmsg_end - Finalize a generic netlink message
451 * @skb: socket buffer the message is stored in
452 * @hdr: user specific header
453 */
454static inline void genlmsg_end(struct sk_buff *skb, void *hdr)
455{
456 nlmsg_end(skb, nlh: hdr - GENL_HDRLEN - NLMSG_HDRLEN);
457}
458
459/**
460 * genlmsg_cancel - Cancel construction of a generic netlink message
461 * @skb: socket buffer the message is stored in
462 * @hdr: generic netlink message header
463 */
464static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr)
465{
466 if (hdr)
467 nlmsg_cancel(skb, nlh: hdr - GENL_HDRLEN - NLMSG_HDRLEN);
468}
469
470/**
471 * genlmsg_multicast_netns_filtered - multicast a netlink message
472 * to a specific netns with filter
473 * function
474 * @family: the generic netlink family
475 * @net: the net namespace
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 * @filter: filter function
481 * @filter_data: filter function private data
482 *
483 * Return: 0 on success, negative error code for failure.
484 */
485static inline int
486genlmsg_multicast_netns_filtered(const struct genl_family *family,
487 struct net *net, struct sk_buff *skb,
488 u32 portid, unsigned int group, gfp_t flags,
489 netlink_filter_fn filter,
490 void *filter_data)
491{
492 if (WARN_ON_ONCE(group >= family->n_mcgrps))
493 return -EINVAL;
494 group = family->mcgrp_offset + group;
495 return nlmsg_multicast_filtered(sk: net->genl_sock, skb, portid, group,
496 flags, filter, filter_data);
497}
498
499/**
500 * genlmsg_multicast_netns - multicast a netlink message to a specific netns
501 * @family: the generic netlink family
502 * @net: the net namespace
503 * @skb: netlink message as socket buffer
504 * @portid: own netlink portid to avoid sending to yourself
505 * @group: offset of multicast group in groups array
506 * @flags: allocation flags
507 */
508static inline int genlmsg_multicast_netns(const struct genl_family *family,
509 struct net *net, struct sk_buff *skb,
510 u32 portid, unsigned int group, gfp_t flags)
511{
512 return genlmsg_multicast_netns_filtered(family, net, skb, portid,
513 group, flags, NULL, NULL);
514}
515
516/**
517 * genlmsg_multicast - multicast a netlink message to the default netns
518 * @family: the generic netlink family
519 * @skb: netlink message as socket buffer
520 * @portid: own netlink portid to avoid sending to yourself
521 * @group: offset of multicast group in groups array
522 * @flags: allocation flags
523 */
524static inline int genlmsg_multicast(const struct genl_family *family,
525 struct sk_buff *skb, u32 portid,
526 unsigned int group, gfp_t flags)
527{
528 return genlmsg_multicast_netns(family, net: &init_net, skb,
529 portid, group, flags);
530}
531
532/**
533 * genlmsg_multicast_allns - multicast a netlink message to all net namespaces
534 * @family: the generic netlink family
535 * @skb: netlink message as socket buffer
536 * @portid: own netlink portid to avoid sending to yourself
537 * @group: offset of multicast group in groups array
538 *
539 * This function must hold the RTNL or rcu_read_lock().
540 */
541int genlmsg_multicast_allns(const struct genl_family *family,
542 struct sk_buff *skb, u32 portid,
543 unsigned int group);
544
545/**
546 * genlmsg_unicast - unicast a netlink message
547 * @net: network namespace to look up @portid in
548 * @skb: netlink message as socket buffer
549 * @portid: netlink portid of the destination socket
550 */
551static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid)
552{
553 return nlmsg_unicast(sk: net->genl_sock, skb, portid);
554}
555
556/**
557 * genlmsg_reply - reply to a request
558 * @skb: netlink message to be sent back
559 * @info: receiver information
560 */
561static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info)
562{
563 return genlmsg_unicast(net: genl_info_net(info), skb, portid: info->snd_portid);
564}
565
566/**
567 * genlmsg_data - head of message payload
568 * @gnlh: genetlink message header
569 */
570static inline void *genlmsg_data(const struct genlmsghdr *gnlh)
571{
572 return ((unsigned char *) gnlh + GENL_HDRLEN);
573}
574
575/**
576 * genlmsg_len - length of message payload
577 * @gnlh: genetlink message header
578 */
579static inline int genlmsg_len(const struct genlmsghdr *gnlh)
580{
581 struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh -
582 NLMSG_HDRLEN);
583 return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
584}
585
586/**
587 * genlmsg_msg_size - length of genetlink message not including padding
588 * @payload: length of message payload
589 */
590static inline int genlmsg_msg_size(int payload)
591{
592 return GENL_HDRLEN + payload;
593}
594
595/**
596 * genlmsg_total_size - length of genetlink message including padding
597 * @payload: length of message payload
598 */
599static inline int genlmsg_total_size(int payload)
600{
601 return NLMSG_ALIGN(genlmsg_msg_size(payload));
602}
603
604/**
605 * genlmsg_new - Allocate a new generic netlink message
606 * @payload: size of the message payload
607 * @flags: the type of memory to allocate.
608 */
609static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
610{
611 return nlmsg_new(payload: genlmsg_total_size(payload), flags);
612}
613
614/**
615 * genl_set_err - report error to genetlink broadcast listeners
616 * @family: the generic netlink family
617 * @net: the network namespace to report the error to
618 * @portid: the PORTID of a process that we want to skip (if any)
619 * @group: the broadcast group that will notice the error
620 * (this is the offset of the multicast group in the groups array)
621 * @code: error code, must be negative (as usual in kernelspace)
622 *
623 * This function returns the number of broadcast listeners that have set the
624 * NETLINK_RECV_NO_ENOBUFS socket option.
625 */
626static inline int genl_set_err(const struct genl_family *family,
627 struct net *net, u32 portid,
628 u32 group, int code)
629{
630 if (WARN_ON_ONCE(group >= family->n_mcgrps))
631 return -EINVAL;
632 group = family->mcgrp_offset + group;
633 return netlink_set_err(ssk: net->genl_sock, portid, group, code);
634}
635
636static inline int genl_has_listeners(const struct genl_family *family,
637 struct net *net, unsigned int group)
638{
639 if (WARN_ON_ONCE(group >= family->n_mcgrps))
640 return -EINVAL;
641 group = family->mcgrp_offset + group;
642 return netlink_has_listeners(sk: net->genl_sock, group);
643}
644#endif /* __NET_GENERIC_NETLINK_H */
645

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