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TOMOYO Linux Cross Reference
Linux/include/net/genetlink.h

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  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  */
 15 struct genl_multicast_group {
 16         char                    name[GENL_NAMSIZ];
 17 };
 18 
 19 struct genl_ops;
 20 struct 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  */
 51 struct 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 
 76 struct 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  */
 90 struct 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 
102 static inline struct net *genl_info_net(struct genl_info *info)
103 {
104         return read_pnet(&info->_net);
105 }
106 
107 static 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 
114 static 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  */
133 struct 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 
146 int genl_register_family(struct genl_family *family);
147 int genl_unregister_family(const struct genl_family *family);
148 void genl_notify(const struct genl_family *family, struct sk_buff *skb,
149                  struct genl_info *info, u32 group, gfp_t flags);
150 
151 void *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  */
160 static 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  */
176 static 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  */
194 static 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  */
210 static 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  */
224 static 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  */
234 static 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  */
249 static 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  */
267 static 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  */
285 int 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  */
294 static 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  */
304 static 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  */
313 static 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  */
322 static 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  */
333 static 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  */
342 static 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  */
352 static 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  */
369 static 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 
379 static 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 

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