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