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. */
13 void genl_lock(void);
14 void 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 */
29 struct genl_multicast_group {
30 char name[GENL_NAMSIZ];
31 u8 flags;
32 };
33
34 struct genl_split_ops;
35 struct 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, not 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 */
78 struct 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 * @user_ptr: user pointers
128 * @extack: extended ACK report struct
129 */
130 struct genl_info {
131 u32 snd_seq;
132 u32 snd_portid;
133 const struct genl_family *family;
134 const struct nlmsghdr * nlhdr;
135 struct genlmsghdr * genlhdr;
136 struct nlattr ** attrs;
137 possible_net_t _net;
138 void * user_ptr[2];
139 struct netlink_ext_ack *extack;
140 };
141
142 static inline struct net *genl_info_net(const struct genl_info *info)
143 {
144 return read_pnet(&info->_net);
145 }
146
147 static inline void genl_info_net_set(struct genl_info *info, struct net *net)
148 {
149 write_pnet(&info->_net, net);
150 }
151
152 static inline void *genl_info_userhdr(const struct genl_info *info)
153 {
154 return (u8 *)info->genlhdr + GENL_HDRLEN;
155 }
156
157 #define GENL_SET_ERR_MSG(info, msg) NL_SET_ERR_MSG((info)->extack, msg)
158
159 #define GENL_SET_ERR_MSG_FMT(info, msg, args...) \
160 NL_SET_ERR_MSG_FMT((info)->extack, msg, ##args)
161
162 /* Report that a root attribute is missing */
163 #define GENL_REQ_ATTR_CHECK(info, attr) ({ \
164 const struct genl_info *__info = (info); \
165 \
166 NL_REQ_ATTR_CHECK(__info->extack, NULL, __info->attrs, (attr)); \
167 })
168
169 enum genl_validate_flags {
170 GENL_DONT_VALIDATE_STRICT = BIT(0),
171 GENL_DONT_VALIDATE_DUMP = BIT(1),
172 GENL_DONT_VALIDATE_DUMP_STRICT = BIT(2),
173 };
174
175 /**
176 * struct genl_small_ops - generic netlink operations (small version)
177 * @cmd: command identifier
178 * @internal_flags: flags used by the family
179 * @flags: GENL_* flags (%GENL_ADMIN_PERM or %GENL_UNS_ADMIN_PERM)
180 * @validate: validation flags from enum genl_validate_flags
181 * @doit: standard command callback
182 * @dumpit: callback for dumpers
183 *
184 * This is a cut-down version of struct genl_ops for users who don't need
185 * most of the ancillary infra and want to save space.
186 */
187 struct genl_small_ops {
188 int (*doit)(struct sk_buff *skb, struct genl_info *info);
189 int (*dumpit)(struct sk_buff *skb, struct netlink_callback *cb);
190 u8 cmd;
191 u8 internal_flags;
192 u8 flags;
193 u8 validate;
194 };
195
196 /**
197 * struct genl_ops - generic netlink operations
198 * @cmd: command identifier
199 * @internal_flags: flags used by the family
200 * @flags: GENL_* flags (%GENL_ADMIN_PERM or %GENL_UNS_ADMIN_PERM)
201 * @maxattr: maximum number of attributes supported
202 * @policy: netlink policy (takes precedence over family policy)
203 * @validate: validation flags from enum genl_validate_flags
204 * @doit: standard command callback
205 * @start: start callback for dumps
206 * @dumpit: callback for dumpers
207 * @done: completion callback for dumps
208 */
209 struct genl_ops {
210 int (*doit)(struct sk_buff *skb,
211 struct genl_info *info);
212 int (*start)(struct netlink_callback *cb);
213 int (*dumpit)(struct sk_buff *skb,
214 struct netlink_callback *cb);
215 int (*done)(struct netlink_callback *cb);
216 const struct nla_policy *policy;
217 unsigned int maxattr;
218 u8 cmd;
219 u8 internal_flags;
220 u8 flags;
221 u8 validate;
222 };
223
224 /**
225 * struct genl_split_ops - generic netlink operations (do/dump split version)
226 * @cmd: command identifier
227 * @internal_flags: flags used by the family
228 * @flags: GENL_* flags (%GENL_ADMIN_PERM or %GENL_UNS_ADMIN_PERM)
229 * @validate: validation flags from enum genl_validate_flags
230 * @policy: netlink policy (takes precedence over family policy)
231 * @maxattr: maximum number of attributes supported
232 *
233 * Do callbacks:
234 * @pre_doit: called before an operation's @doit callback, it may
235 * do additional, common, filtering and return an error
236 * @doit: standard command callback
237 * @post_doit: called after an operation's @doit callback, it may
238 * undo operations done by pre_doit, for example release locks
239 *
240 * Dump callbacks:
241 * @start: start callback for dumps
242 * @dumpit: callback for dumpers
243 * @done: completion callback for dumps
244 *
245 * Do callbacks can be used if %GENL_CMD_CAP_DO is set in @flags.
246 * Dump callbacks can be used if %GENL_CMD_CAP_DUMP is set in @flags.
247 * Exactly one of those flags must be set.
248 */
249 struct genl_split_ops {
250 union {
251 struct {
252 int (*pre_doit)(const struct genl_split_ops *ops,
253 struct sk_buff *skb,
254 struct genl_info *info);
255 int (*doit)(struct sk_buff *skb,
256 struct genl_info *info);
257 void (*post_doit)(const struct genl_split_ops *ops,
258 struct sk_buff *skb,
259 struct genl_info *info);
260 };
261 struct {
262 int (*start)(struct netlink_callback *cb);
263 int (*dumpit)(struct sk_buff *skb,
264 struct netlink_callback *cb);
265 int (*done)(struct netlink_callback *cb);
266 };
267 };
268 const struct nla_policy *policy;
269 unsigned int maxattr;
270 u8 cmd;
271 u8 internal_flags;
272 u8 flags;
273 u8 validate;
274 };
275
276 /**
277 * struct genl_dumpit_info - info that is available during dumpit op call
278 * @op: generic netlink ops - for internal genl code usage
279 * @attrs: netlink attributes
280 * @info: struct genl_info describing the request
281 */
282 struct genl_dumpit_info {
283 struct genl_split_ops op;
284 struct genl_info info;
285 };
286
287 static inline const struct genl_dumpit_info *
288 genl_dumpit_info(struct netlink_callback *cb)
289 {
290 return cb->data;
291 }
292
293 static inline const struct genl_info *
294 genl_info_dump(struct netlink_callback *cb)
295 {
296 return &genl_dumpit_info(cb)->info;
297 }
298
299 /**
300 * genl_info_init_ntf() - initialize genl_info for notifications
301 * @info: genl_info struct to set up
302 * @family: pointer to the genetlink family
303 * @cmd: command to be used in the notification
304 *
305 * Initialize a locally declared struct genl_info to pass to various APIs.
306 * Intended to be used when creating notifications.
307 */
308 static inline void
309 genl_info_init_ntf(struct genl_info *info, const struct genl_family *family,
310 u8 cmd)
311 {
312 struct genlmsghdr *hdr = (void *) &info->user_ptr[0];
313
314 memset(info, 0, sizeof(*info));
315 info->family = family;
316 info->genlhdr = hdr;
317 hdr->cmd = cmd;
318 }
319
320 static inline bool genl_info_is_ntf(const struct genl_info *info)
321 {
322 return !info->nlhdr;
323 }
324
325 void *__genl_sk_priv_get(struct genl_family *family, struct sock *sk);
326 void *genl_sk_priv_get(struct genl_family *family, struct sock *sk);
327 int genl_register_family(struct genl_family *family);
328 int genl_unregister_family(const struct genl_family *family);
329 void genl_notify(const struct genl_family *family, struct sk_buff *skb,
330 struct genl_info *info, u32 group, gfp_t flags);
331
332 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
333 const struct genl_family *family, int flags, u8 cmd);
334
335 static inline void *
336 __genlmsg_iput(struct sk_buff *skb, const struct genl_info *info, int flags)
337 {
338 return genlmsg_put(skb, info->snd_portid, info->snd_seq, info->family,
339 flags, info->genlhdr->cmd);
340 }
341
342 /**
343 * genlmsg_iput - start genetlink message based on genl_info
344 * @skb: skb in which message header will be placed
345 * @info: genl_info as provided to do/dump handlers
346 *
347 * Convenience wrapper which starts a genetlink message based on
348 * information in user request. @info should be either the struct passed
349 * by genetlink core to do/dump handlers (when constructing replies to
350 * such requests) or a struct initialized by genl_info_init_ntf()
351 * when constructing notifications.
352 *
353 * Returns pointer to new genetlink header.
354 */
355 static inline void *
356 genlmsg_iput(struct sk_buff *skb, const struct genl_info *info)
357 {
358 return __genlmsg_iput(skb, info, 0);
359 }
360
361 /**
362 * genlmsg_nlhdr - Obtain netlink header from user specified header
363 * @user_hdr: user header as returned from genlmsg_put()
364 *
365 * Returns pointer to netlink header.
366 */
367 static inline struct nlmsghdr *genlmsg_nlhdr(void *user_hdr)
368 {
369 return (struct nlmsghdr *)((char *)user_hdr -
370 GENL_HDRLEN -
371 NLMSG_HDRLEN);
372 }
373
374 /**
375 * genlmsg_parse_deprecated - parse attributes of a genetlink message
376 * @nlh: netlink message header
377 * @family: genetlink message family
378 * @tb: destination array with maxtype+1 elements
379 * @maxtype: maximum attribute type to be expected
380 * @policy: validation policy
381 * @extack: extended ACK report struct
382 */
383 static inline int genlmsg_parse_deprecated(const struct nlmsghdr *nlh,
384 const struct genl_family *family,
385 struct nlattr *tb[], int maxtype,
386 const struct nla_policy *policy,
387 struct netlink_ext_ack *extack)
388 {
389 return __nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype,
390 policy, NL_VALIDATE_LIBERAL, extack);
391 }
392
393 /**
394 * genlmsg_parse - parse attributes of a genetlink message
395 * @nlh: netlink message header
396 * @family: genetlink message family
397 * @tb: destination array with maxtype+1 elements
398 * @maxtype: maximum attribute type to be expected
399 * @policy: validation policy
400 * @extack: extended ACK report struct
401 */
402 static inline int genlmsg_parse(const struct nlmsghdr *nlh,
403 const struct genl_family *family,
404 struct nlattr *tb[], int maxtype,
405 const struct nla_policy *policy,
406 struct netlink_ext_ack *extack)
407 {
408 return __nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype,
409 policy, NL_VALIDATE_STRICT, extack);
410 }
411
412 /**
413 * genl_dump_check_consistent - check if sequence is consistent and advertise if not
414 * @cb: netlink callback structure that stores the sequence number
415 * @user_hdr: user header as returned from genlmsg_put()
416 *
417 * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it
418 * simpler to use with generic netlink.
419 */
420 static inline void genl_dump_check_consistent(struct netlink_callback *cb,
421 void *user_hdr)
422 {
423 nl_dump_check_consistent(cb, genlmsg_nlhdr(user_hdr));
424 }
425
426 /**
427 * genlmsg_put_reply - Add generic netlink header to a reply message
428 * @skb: socket buffer holding the message
429 * @info: receiver info
430 * @family: generic netlink family
431 * @flags: netlink message flags
432 * @cmd: generic netlink command
433 *
434 * Returns pointer to user specific header
435 */
436 static inline void *genlmsg_put_reply(struct sk_buff *skb,
437 struct genl_info *info,
438 const struct genl_family *family,
439 int flags, u8 cmd)
440 {
441 return genlmsg_put(skb, info->snd_portid, info->snd_seq, family,
442 flags, cmd);
443 }
444
445 /**
446 * genlmsg_end - Finalize a generic netlink message
447 * @skb: socket buffer the message is stored in
448 * @hdr: user specific header
449 */
450 static inline void genlmsg_end(struct sk_buff *skb, void *hdr)
451 {
452 nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
453 }
454
455 /**
456 * genlmsg_cancel - Cancel construction of a generic netlink message
457 * @skb: socket buffer the message is stored in
458 * @hdr: generic netlink message header
459 */
460 static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr)
461 {
462 if (hdr)
463 nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
464 }
465
466 /**
467 * genlmsg_multicast_netns_filtered - multicast a netlink message
468 * to a specific netns with filter
469 * function
470 * @family: the generic netlink family
471 * @net: the net namespace
472 * @skb: netlink message as socket buffer
473 * @portid: own netlink portid to avoid sending to yourself
474 * @group: offset of multicast group in groups array
475 * @flags: allocation flags
476 * @filter: filter function
477 * @filter_data: filter function private data
478 *
479 * Return: 0 on success, negative error code for failure.
480 */
481 static inline int
482 genlmsg_multicast_netns_filtered(const struct genl_family *family,
483 struct net *net, struct sk_buff *skb,
484 u32 portid, unsigned int group, gfp_t flags,
485 netlink_filter_fn filter,
486 void *filter_data)
487 {
488 if (WARN_ON_ONCE(group >= family->n_mcgrps))
489 return -EINVAL;
490 group = family->mcgrp_offset + group;
491 return nlmsg_multicast_filtered(net->genl_sock, skb, portid, group,
492 flags, filter, filter_data);
493 }
494
495 /**
496 * genlmsg_multicast_netns - multicast a netlink message to a specific netns
497 * @family: the generic netlink family
498 * @net: the net namespace
499 * @skb: netlink message as socket buffer
500 * @portid: own netlink portid to avoid sending to yourself
501 * @group: offset of multicast group in groups array
502 * @flags: allocation flags
503 */
504 static inline int genlmsg_multicast_netns(const struct genl_family *family,
505 struct net *net, struct sk_buff *skb,
506 u32 portid, unsigned int group, gfp_t flags)
507 {
508 return genlmsg_multicast_netns_filtered(family, net, skb, portid,
509 group, flags, NULL, NULL);
510 }
511
512 /**
513 * genlmsg_multicast - multicast a netlink message to the default netns
514 * @family: the generic netlink family
515 * @skb: netlink message as socket buffer
516 * @portid: own netlink portid to avoid sending to yourself
517 * @group: offset of multicast group in groups array
518 * @flags: allocation flags
519 */
520 static inline int genlmsg_multicast(const struct genl_family *family,
521 struct sk_buff *skb, u32 portid,
522 unsigned int group, gfp_t flags)
523 {
524 return genlmsg_multicast_netns(family, &init_net, skb,
525 portid, group, flags);
526 }
527
528 /**
529 * genlmsg_multicast_allns - multicast a netlink message to all net namespaces
530 * @family: the generic netlink family
531 * @skb: netlink message as socket buffer
532 * @portid: own netlink portid to avoid sending to yourself
533 * @group: offset of multicast group in groups array
534 * @flags: allocation flags
535 *
536 * This function must hold the RTNL or rcu_read_lock().
537 */
538 int genlmsg_multicast_allns(const struct genl_family *family,
539 struct sk_buff *skb, u32 portid,
540 unsigned int group, gfp_t flags);
541
542 /**
543 * genlmsg_unicast - unicast a netlink message
544 * @net: network namespace to look up @portid in
545 * @skb: netlink message as socket buffer
546 * @portid: netlink portid of the destination socket
547 */
548 static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid)
549 {
550 return nlmsg_unicast(net->genl_sock, skb, portid);
551 }
552
553 /**
554 * genlmsg_reply - reply to a request
555 * @skb: netlink message to be sent back
556 * @info: receiver information
557 */
558 static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info)
559 {
560 return genlmsg_unicast(genl_info_net(info), skb, info->snd_portid);
561 }
562
563 /**
564 * genlmsg_data - head of message payload
565 * @gnlh: genetlink message header
566 */
567 static inline void *genlmsg_data(const struct genlmsghdr *gnlh)
568 {
569 return ((unsigned char *) gnlh + GENL_HDRLEN);
570 }
571
572 /**
573 * genlmsg_len - length of message payload
574 * @gnlh: genetlink message header
575 */
576 static inline int genlmsg_len(const struct genlmsghdr *gnlh)
577 {
578 struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh -
579 NLMSG_HDRLEN);
580 return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
581 }
582
583 /**
584 * genlmsg_msg_size - length of genetlink message not including padding
585 * @payload: length of message payload
586 */
587 static inline int genlmsg_msg_size(int payload)
588 {
589 return GENL_HDRLEN + payload;
590 }
591
592 /**
593 * genlmsg_total_size - length of genetlink message including padding
594 * @payload: length of message payload
595 */
596 static inline int genlmsg_total_size(int payload)
597 {
598 return NLMSG_ALIGN(genlmsg_msg_size(payload));
599 }
600
601 /**
602 * genlmsg_new - Allocate a new generic netlink message
603 * @payload: size of the message payload
604 * @flags: the type of memory to allocate.
605 */
606 static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
607 {
608 return nlmsg_new(genlmsg_total_size(payload), flags);
609 }
610
611 /**
612 * genl_set_err - report error to genetlink broadcast listeners
613 * @family: the generic netlink family
614 * @net: the network namespace to report the error to
615 * @portid: the PORTID of a process that we want to skip (if any)
616 * @group: the broadcast group that will notice the error
617 * (this is the offset of the multicast group in the groups array)
618 * @code: error code, must be negative (as usual in kernelspace)
619 *
620 * This function returns the number of broadcast listeners that have set the
621 * NETLINK_RECV_NO_ENOBUFS socket option.
622 */
623 static inline int genl_set_err(const struct genl_family *family,
624 struct net *net, u32 portid,
625 u32 group, int code)
626 {
627 if (WARN_ON_ONCE(group >= family->n_mcgrps))
628 return -EINVAL;
629 group = family->mcgrp_offset + group;
630 return netlink_set_err(net->genl_sock, portid, group, code);
631 }
632
633 static inline int genl_has_listeners(const struct genl_family *family,
634 struct net *net, unsigned int group)
635 {
636 if (WARN_ON_ONCE(group >= family->n_mcgrps))
637 return -EINVAL;
638 group = family->mcgrp_offset + group;
639 return netlink_has_listeners(net->genl_sock, group);
640 }
641 #endif /* __NET_GENERIC_NETLINK_H */
642
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