include/net/genetlink.h

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