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Linux/include/net/genetlink.h

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  1 #ifndef __NET_GENERIC_NETLINK_H
  2 #define __NET_GENERIC_NETLINK_H
  3 
  4 #include <linux/genetlink.h>
  5 #include <net/netlink.h>
  6 #include <net/net_namespace.h>
  7 
  8 #define GENLMSG_DEFAULT_SIZE (NLMSG_DEFAULT_SIZE - GENL_HDRLEN)
  9 
 10 /**
 11  * struct genl_multicast_group - generic netlink multicast group
 12  * @name: name of the multicast group, names are per-family
 13  */
 14 struct genl_multicast_group {
 15         char                    name[GENL_NAMSIZ];
 16 };
 17 
 18 struct genl_ops;
 19 struct genl_info;
 20 
 21 /**
 22  * struct genl_family - generic netlink family
 23  * @id: protocol family idenfitier
 24  * @hdrsize: length of user specific header in bytes
 25  * @name: name of family
 26  * @version: protocol version
 27  * @maxattr: maximum number of attributes supported
 28  * @netnsok: set to true if the family can handle network
 29  *      namespaces and should be presented in all of them
 30  * @parallel_ops: operations can be called in parallel and aren't
 31  *      synchronized by the core genetlink code
 32  * @pre_doit: called before an operation's doit callback, it may
 33  *      do additional, common, filtering and return an error
 34  * @post_doit: called after an operation's doit callback, it may
 35  *      undo operations done by pre_doit, for example release locks
 36  * @mcast_bind: a socket bound to the given multicast group (which
 37  *      is given as the offset into the groups array)
 38  * @mcast_unbind: a socket was unbound from the given multicast group.
 39  *      Note that unbind() will not be called symmetrically if the
 40  *      generic netlink family is removed while there are still open
 41  *      sockets.
 42  * @attrbuf: buffer to store parsed attributes
 43  * @family_list: family list
 44  * @mcgrps: multicast groups used by this family (private)
 45  * @n_mcgrps: number of multicast groups (private)
 46  * @mcgrp_offset: starting number of multicast group IDs in this family
 47  * @ops: the operations supported by this family (private)
 48  * @n_ops: number of operations supported by this family (private)
 49  */
 50 struct genl_family {
 51         unsigned int            id;
 52         unsigned int            hdrsize;
 53         char                    name[GENL_NAMSIZ];
 54         unsigned int            version;
 55         unsigned int            maxattr;
 56         bool                    netnsok;
 57         bool                    parallel_ops;
 58         int                     (*pre_doit)(const struct genl_ops *ops,
 59                                             struct sk_buff *skb,
 60                                             struct genl_info *info);
 61         void                    (*post_doit)(const struct genl_ops *ops,
 62                                              struct sk_buff *skb,
 63                                              struct genl_info *info);
 64         int                     (*mcast_bind)(struct net *net, int group);
 65         void                    (*mcast_unbind)(struct net *net, int group);
 66         struct nlattr **        attrbuf;        /* private */
 67         const struct genl_ops * ops;            /* private */
 68         const struct genl_multicast_group *mcgrps; /* private */
 69         unsigned int            n_ops;          /* private */
 70         unsigned int            n_mcgrps;       /* private */
 71         unsigned int            mcgrp_offset;   /* private */
 72         struct list_head        family_list;    /* private */
 73         struct module           *module;
 74 };
 75 
 76 /**
 77  * struct genl_info - receiving information
 78  * @snd_seq: sending sequence number
 79  * @snd_portid: netlink portid of sender
 80  * @nlhdr: netlink message header
 81  * @genlhdr: generic netlink message header
 82  * @userhdr: user specific header
 83  * @attrs: netlink attributes
 84  * @_net: network namespace
 85  * @user_ptr: user pointers
 86  */
 87 struct genl_info {
 88         u32                     snd_seq;
 89         u32                     snd_portid;
 90         struct nlmsghdr *       nlhdr;
 91         struct genlmsghdr *     genlhdr;
 92         void *                  userhdr;
 93         struct nlattr **        attrs;
 94         possible_net_t          _net;
 95         void *                  user_ptr[2];
 96 };
 97 
 98 static inline struct net *genl_info_net(struct genl_info *info)
 99 {
100         return read_pnet(&info->_net);
101 }
102 
103 static inline void genl_info_net_set(struct genl_info *info, struct net *net)
104 {
105         write_pnet(&info->_net, net);
106 }
107 
108 /**
109  * struct genl_ops - generic netlink operations
110  * @cmd: command identifier
111  * @internal_flags: flags used by the family
112  * @flags: flags
113  * @policy: attribute validation policy
114  * @doit: standard command callback
115  * @start: start callback for dumps
116  * @dumpit: callback for dumpers
117  * @done: completion callback for dumps
118  * @ops_list: operations list
119  */
120 struct genl_ops {
121         const struct nla_policy *policy;
122         int                    (*doit)(struct sk_buff *skb,
123                                        struct genl_info *info);
124         int                    (*start)(struct netlink_callback *cb);
125         int                    (*dumpit)(struct sk_buff *skb,
126                                          struct netlink_callback *cb);
127         int                    (*done)(struct netlink_callback *cb);
128         u8                      cmd;
129         u8                      internal_flags;
130         u8                      flags;
131 };
132 
133 int __genl_register_family(struct genl_family *family);
134 
135 static inline int genl_register_family(struct genl_family *family)
136 {
137         family->module = THIS_MODULE;
138         return __genl_register_family(family);
139 }
140 
141 /**
142  * genl_register_family_with_ops - register a generic netlink family with ops
143  * @family: generic netlink family
144  * @ops: operations to be registered
145  * @n_ops: number of elements to register
146  *
147  * Registers the specified family and operations from the specified table.
148  * Only one family may be registered with the same family name or identifier.
149  *
150  * The family id may equal GENL_ID_GENERATE causing an unique id to
151  * be automatically generated and assigned.
152  *
153  * Either a doit or dumpit callback must be specified for every registered
154  * operation or the function will fail. Only one operation structure per
155  * command identifier may be registered.
156  *
157  * See include/net/genetlink.h for more documenation on the operations
158  * structure.
159  *
160  * Return 0 on success or a negative error code.
161  */
162 static inline int
163 _genl_register_family_with_ops_grps(struct genl_family *family,
164                                     const struct genl_ops *ops, size_t n_ops,
165                                     const struct genl_multicast_group *mcgrps,
166                                     size_t n_mcgrps)
167 {
168         family->module = THIS_MODULE;
169         family->ops = ops;
170         family->n_ops = n_ops;
171         family->mcgrps = mcgrps;
172         family->n_mcgrps = n_mcgrps;
173         return __genl_register_family(family);
174 }
175 
176 #define genl_register_family_with_ops(family, ops)                      \
177         _genl_register_family_with_ops_grps((family),                   \
178                                             (ops), ARRAY_SIZE(ops),     \
179                                             NULL, 0)
180 #define genl_register_family_with_ops_groups(family, ops, grps) \
181         _genl_register_family_with_ops_grps((family),                   \
182                                             (ops), ARRAY_SIZE(ops),     \
183                                             (grps), ARRAY_SIZE(grps))
184 
185 int genl_unregister_family(struct genl_family *family);
186 void genl_notify(struct genl_family *family, struct sk_buff *skb,
187                  struct genl_info *info, u32 group, gfp_t flags);
188 
189 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
190                   struct genl_family *family, int flags, u8 cmd);
191 
192 /**
193  * genlmsg_nlhdr - Obtain netlink header from user specified header
194  * @user_hdr: user header as returned from genlmsg_put()
195  * @family: generic netlink family
196  *
197  * Returns pointer to netlink header.
198  */
199 static inline struct nlmsghdr *genlmsg_nlhdr(void *user_hdr,
200                                              struct genl_family *family)
201 {
202         return (struct nlmsghdr *)((char *)user_hdr -
203                                    family->hdrsize -
204                                    GENL_HDRLEN -
205                                    NLMSG_HDRLEN);
206 }
207 
208 /**
209  * genlmsg_parse - parse attributes of a genetlink message
210  * @nlh: netlink message header
211  * @family: genetlink message family
212  * @tb: destination array with maxtype+1 elements
213  * @maxtype: maximum attribute type to be expected
214  * @policy: validation policy
215  * */
216 static inline int genlmsg_parse(const struct nlmsghdr *nlh,
217                                 const struct genl_family *family,
218                                 struct nlattr *tb[], int maxtype,
219                                 const struct nla_policy *policy)
220 {
221         return nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype,
222                            policy);
223 }
224 
225 /**
226  * genl_dump_check_consistent - check if sequence is consistent and advertise if not
227  * @cb: netlink callback structure that stores the sequence number
228  * @user_hdr: user header as returned from genlmsg_put()
229  * @family: generic netlink family
230  *
231  * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it
232  * simpler to use with generic netlink.
233  */
234 static inline void genl_dump_check_consistent(struct netlink_callback *cb,
235                                               void *user_hdr,
236                                               struct genl_family *family)
237 {
238         nl_dump_check_consistent(cb, genlmsg_nlhdr(user_hdr, family));
239 }
240 
241 /**
242  * genlmsg_put_reply - Add generic netlink header to a reply message
243  * @skb: socket buffer holding the message
244  * @info: receiver info
245  * @family: generic netlink family
246  * @flags: netlink message flags
247  * @cmd: generic netlink command
248  *
249  * Returns pointer to user specific header
250  */
251 static inline void *genlmsg_put_reply(struct sk_buff *skb,
252                                       struct genl_info *info,
253                                       struct genl_family *family,
254                                       int flags, u8 cmd)
255 {
256         return genlmsg_put(skb, info->snd_portid, info->snd_seq, family,
257                            flags, cmd);
258 }
259 
260 /**
261  * genlmsg_end - Finalize a generic netlink message
262  * @skb: socket buffer the message is stored in
263  * @hdr: user specific header
264  */
265 static inline void genlmsg_end(struct sk_buff *skb, void *hdr)
266 {
267         nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
268 }
269 
270 /**
271  * genlmsg_cancel - Cancel construction of a generic netlink message
272  * @skb: socket buffer the message is stored in
273  * @hdr: generic netlink message header
274  */
275 static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr)
276 {
277         if (hdr)
278                 nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
279 }
280 
281 /**
282  * genlmsg_multicast_netns - multicast a netlink message to a specific netns
283  * @family: the generic netlink family
284  * @net: the net namespace
285  * @skb: netlink message as socket buffer
286  * @portid: own netlink portid to avoid sending to yourself
287  * @group: offset of multicast group in groups array
288  * @flags: allocation flags
289  */
290 static inline int genlmsg_multicast_netns(struct genl_family *family,
291                                           struct net *net, struct sk_buff *skb,
292                                           u32 portid, unsigned int group, gfp_t flags)
293 {
294         if (WARN_ON_ONCE(group >= family->n_mcgrps))
295                 return -EINVAL;
296         group = family->mcgrp_offset + group;
297         return nlmsg_multicast(net->genl_sock, skb, portid, group, flags);
298 }
299 
300 /**
301  * genlmsg_multicast - multicast a netlink message to the default netns
302  * @family: the generic netlink family
303  * @skb: netlink message as socket buffer
304  * @portid: own netlink portid to avoid sending to yourself
305  * @group: offset of multicast group in groups array
306  * @flags: allocation flags
307  */
308 static inline int genlmsg_multicast(struct genl_family *family,
309                                     struct sk_buff *skb, u32 portid,
310                                     unsigned int group, gfp_t flags)
311 {
312         return genlmsg_multicast_netns(family, &init_net, skb,
313                                        portid, group, flags);
314 }
315 
316 /**
317  * genlmsg_multicast_allns - multicast a netlink message to all net namespaces
318  * @family: the generic netlink family
319  * @skb: netlink message as socket buffer
320  * @portid: own netlink portid to avoid sending to yourself
321  * @group: offset of multicast group in groups array
322  * @flags: allocation flags
323  *
324  * This function must hold the RTNL or rcu_read_lock().
325  */
326 int genlmsg_multicast_allns(struct genl_family *family,
327                             struct sk_buff *skb, u32 portid,
328                             unsigned int group, gfp_t flags);
329 
330 /**
331  * genlmsg_unicast - unicast a netlink message
332  * @skb: netlink message as socket buffer
333  * @portid: netlink portid of the destination socket
334  */
335 static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid)
336 {
337         return nlmsg_unicast(net->genl_sock, skb, portid);
338 }
339 
340 /**
341  * genlmsg_reply - reply to a request
342  * @skb: netlink message to be sent back
343  * @info: receiver information
344  */
345 static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info)
346 {
347         return genlmsg_unicast(genl_info_net(info), skb, info->snd_portid);
348 }
349 
350 /**
351  * gennlmsg_data - head of message payload
352  * @gnlh: genetlink message header
353  */
354 static inline void *genlmsg_data(const struct genlmsghdr *gnlh)
355 {
356         return ((unsigned char *) gnlh + GENL_HDRLEN);
357 }
358 
359 /**
360  * genlmsg_len - length of message payload
361  * @gnlh: genetlink message header
362  */
363 static inline int genlmsg_len(const struct genlmsghdr *gnlh)
364 {
365         struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh -
366                                                         NLMSG_HDRLEN);
367         return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
368 }
369 
370 /**
371  * genlmsg_msg_size - length of genetlink message not including padding
372  * @payload: length of message payload
373  */
374 static inline int genlmsg_msg_size(int payload)
375 {
376         return GENL_HDRLEN + payload;
377 }
378 
379 /**
380  * genlmsg_total_size - length of genetlink message including padding
381  * @payload: length of message payload
382  */
383 static inline int genlmsg_total_size(int payload)
384 {
385         return NLMSG_ALIGN(genlmsg_msg_size(payload));
386 }
387 
388 /**
389  * genlmsg_new - Allocate a new generic netlink message
390  * @payload: size of the message payload
391  * @flags: the type of memory to allocate.
392  */
393 static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
394 {
395         return nlmsg_new(genlmsg_total_size(payload), flags);
396 }
397 
398 /**
399  * genl_set_err - report error to genetlink broadcast listeners
400  * @family: the generic netlink family
401  * @net: the network namespace to report the error to
402  * @portid: the PORTID of a process that we want to skip (if any)
403  * @group: the broadcast group that will notice the error
404  *      (this is the offset of the multicast group in the groups array)
405  * @code: error code, must be negative (as usual in kernelspace)
406  *
407  * This function returns the number of broadcast listeners that have set the
408  * NETLINK_RECV_NO_ENOBUFS socket option.
409  */
410 static inline int genl_set_err(struct genl_family *family, struct net *net,
411                                u32 portid, u32 group, int code)
412 {
413         if (WARN_ON_ONCE(group >= family->n_mcgrps))
414                 return -EINVAL;
415         group = family->mcgrp_offset + group;
416         return netlink_set_err(net->genl_sock, portid, group, code);
417 }
418 
419 static inline int genl_has_listeners(struct genl_family *family,
420                                      struct net *net, unsigned int group)
421 {
422         if (WARN_ON_ONCE(group >= family->n_mcgrps))
423                 return -EINVAL;
424         group = family->mcgrp_offset + group;
425         return netlink_has_listeners(net->genl_sock, group);
426 }
427 #endif  /* __NET_GENERIC_NETLINK_H */
428 

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