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  * @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  * @dst_sk: destination socket
  87  */
  88 struct genl_info {
  89         u32                     snd_seq;
  90         u32                     snd_portid;
  91         struct nlmsghdr *       nlhdr;
  92         struct genlmsghdr *     genlhdr;
  93         void *                  userhdr;
  94         struct nlattr **        attrs;
  95 #ifdef CONFIG_NET_NS
  96         struct net *            _net;
  97 #endif
  98         void *                  user_ptr[2];
  99         struct sock *           dst_sk;
 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 /**
 113  * struct genl_ops - generic netlink operations
 114  * @cmd: command identifier
 115  * @internal_flags: flags used by the family
 116  * @flags: flags
 117  * @policy: attribute validation policy
 118  * @doit: standard command callback
 119  * @dumpit: callback for dumpers
 120  * @done: completion callback for dumps
 121  * @ops_list: operations list
 122  */
 123 struct genl_ops {
 124         const struct nla_policy *policy;
 125         int                    (*doit)(struct sk_buff *skb,
 126                                        struct genl_info *info);
 127         int                    (*dumpit)(struct sk_buff *skb,
 128                                          struct netlink_callback *cb);
 129         int                    (*done)(struct netlink_callback *cb);
 130         u8                      cmd;
 131         u8                      internal_flags;
 132         u8                      flags;
 133 };
 134
 135 int __genl_register_family(struct genl_family *family);
 136
 137 static inline int genl_register_family(struct genl_family *family)
 138 {
 139         family->module = THIS_MODULE;
 140         return __genl_register_family(family);
 141 }
 142
 143 /**
 144  * genl_register_family_with_ops - register a generic netlink family with ops
 145  * @family: generic netlink family
 146  * @ops: operations to be registered
 147  * @n_ops: number of elements to register
 148  *
 149  * Registers the specified family and operations from the specified table.
 150  * Only one family may be registered with the same family name or identifier.
 151  *
 152  * The family id may equal GENL_ID_GENERATE causing an unique id to
 153  * be automatically generated and assigned.
 154  *
 155  * Either a doit or dumpit callback must be specified for every registered
 156  * operation or the function will fail. Only one operation structure per
 157  * command identifier may be registered.
 158  *
 159  * See include/net/genetlink.h for more documenation on the operations
 160  * structure.
 161  *
 162  * Return 0 on success or a negative error code.
 163  */
 164 static inline int
 165 _genl_register_family_with_ops_grps(struct genl_family *family,
 166                                     const struct genl_ops *ops, size_t n_ops,
 167                                     const struct genl_multicast_group *mcgrps,
 168                                     size_t n_mcgrps)
 169 {
 170         family->module = THIS_MODULE;
 171         family->ops = ops;
 172         family->n_ops = n_ops;
 173         family->mcgrps = mcgrps;
 174         family->n_mcgrps = n_mcgrps;
 175         return __genl_register_family(family);
 176 }
 177
 178 #define genl_register_family_with_ops(family, ops)                      \
 179         _genl_register_family_with_ops_grps((family),                   \
 180                                             (ops), ARRAY_SIZE(ops),     \
 181                                             NULL, 0)
 182 #define genl_register_family_with_ops_groups(family, ops, grps) \
 183         _genl_register_family_with_ops_grps((family),                   \
 184                                             (ops), ARRAY_SIZE(ops),     \
 185                                             (grps), ARRAY_SIZE(grps))
 186
 187 int genl_unregister_family(struct genl_family *family);
 188 void genl_notify(struct genl_family *family,
 189                  struct sk_buff *skb, struct net *net, u32 portid,
 190                  u32 group, struct nlmsghdr *nlh, gfp_t flags);
 191
 192 struct sk_buff *genlmsg_new_unicast(size_t payload, struct genl_info *info,
 193                                     gfp_t flags);
 194 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 195                   struct genl_family *family, int flags, u8 cmd);
 196
 197 /**
 198  * genlmsg_nlhdr - Obtain netlink header from user specified header
 199  * @user_hdr: user header as returned from genlmsg_put()
 200  * @family: generic netlink family
 201  *
 202  * Returns pointer to netlink header.
 203  */
 204 static inline struct nlmsghdr *genlmsg_nlhdr(void *user_hdr,
 205                                              struct genl_family *family)
 206 {
 207         return (struct nlmsghdr *)((char *)user_hdr -
 208                                    family->hdrsize -
 209                                    GENL_HDRLEN -
 210                                    NLMSG_HDRLEN);
 211 }
 212
 213 /**
 214  * genlmsg_parse - parse attributes of a genetlink message
 215  * @nlh: netlink message header
 216  * @family: genetlink message family
 217  * @tb: destination array with maxtype+1 elements
 218  * @maxtype: maximum attribute type to be expected
 219  * @policy: validation policy
 220  * */
 221 static inline int genlmsg_parse(const struct nlmsghdr *nlh,
 222                                 const struct genl_family *family,
 223                                 struct nlattr *tb[], int maxtype,
 224                                 const struct nla_policy *policy)
 225 {
 226         return nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype,
 227                            policy);
 228 }
 229
 230 /**
 231  * genl_dump_check_consistent - check if sequence is consistent and advertise if not
 232  * @cb: netlink callback structure that stores the sequence number
 233  * @user_hdr: user header as returned from genlmsg_put()
 234  * @family: generic netlink family
 235  *
 236  * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it
 237  * simpler to use with generic netlink.
 238  */
 239 static inline void genl_dump_check_consistent(struct netlink_callback *cb,
 240                                               void *user_hdr,
 241                                               struct genl_family *family)
 242 {
 243         nl_dump_check_consistent(cb, genlmsg_nlhdr(user_hdr, family));
 244 }
 245
 246 /**
 247  * genlmsg_put_reply - Add generic netlink header to a reply message
 248  * @skb: socket buffer holding the message
 249  * @info: receiver info
 250  * @family: generic netlink family
 251  * @flags: netlink message flags
 252  * @cmd: generic netlink command
 253  *
 254  * Returns pointer to user specific header
 255  */
 256 static inline void *genlmsg_put_reply(struct sk_buff *skb,
 257                                       struct genl_info *info,
 258                                       struct genl_family *family,
 259                                       int flags, u8 cmd)
 260 {
 261         return genlmsg_put(skb, info->snd_portid, info->snd_seq, family,
 262                            flags, cmd);
 263 }
 264
 265 /**
 266  * genlmsg_end - Finalize a generic netlink message
 267  * @skb: socket buffer the message is stored in
 268  * @hdr: user specific header
 269  */
 270 static inline void genlmsg_end(struct sk_buff *skb, void *hdr)
 271 {
 272         nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
 273 }
 274
 275 /**
 276  * genlmsg_cancel - Cancel construction of a generic netlink message
 277  * @skb: socket buffer the message is stored in
 278  * @hdr: generic netlink message header
 279  */
 280 static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr)
 281 {
 282         if (hdr)
 283                 nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
 284 }
 285
 286 /**
 287  * genlmsg_multicast_netns - multicast a netlink message to a specific netns
 288  * @family: the generic netlink family
 289  * @net: the net namespace
 290  * @skb: netlink message as socket buffer
 291  * @portid: own netlink portid to avoid sending to yourself
 292  * @group: offset of multicast group in groups array
 293  * @flags: allocation flags
 294  */
 295 static inline int genlmsg_multicast_netns(struct genl_family *family,
 296                                           struct net *net, struct sk_buff *skb,
 297                                           u32 portid, unsigned int group, gfp_t flags)
 298 {
 299         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 300                 return -EINVAL;
 301         group = family->mcgrp_offset + group;
 302         return nlmsg_multicast(net->genl_sock, skb, portid, group, flags);
 303 }
 304
 305 /**
 306  * genlmsg_multicast - multicast a netlink message to the default netns
 307  * @family: the generic netlink family
 308  * @skb: netlink message as socket buffer
 309  * @portid: own netlink portid to avoid sending to yourself
 310  * @group: offset of multicast group in groups array
 311  * @flags: allocation flags
 312  */
 313 static inline int genlmsg_multicast(struct genl_family *family,
 314                                     struct sk_buff *skb, u32 portid,
 315                                     unsigned int group, gfp_t flags)
 316 {
 317         return genlmsg_multicast_netns(family, &init_net, skb,
 318                                        portid, group, flags);
 319 }
 320
 321 /**
 322  * genlmsg_multicast_allns - multicast a netlink message to all net namespaces
 323  * @family: the generic netlink family
 324  * @skb: netlink message as socket buffer
 325  * @portid: own netlink portid to avoid sending to yourself
 326  * @group: offset of multicast group in groups array
 327  * @flags: allocation flags
 328  *
 329  * This function must hold the RTNL or rcu_read_lock().
 330  */
 331 int genlmsg_multicast_allns(struct genl_family *family,
 332                             struct sk_buff *skb, u32 portid,
 333                             unsigned int group, gfp_t flags);
 334
 335 /**
 336  * genlmsg_unicast - unicast a netlink message
 337  * @skb: netlink message as socket buffer
 338  * @portid: netlink portid of the destination socket
 339  */
 340 static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid)
 341 {
 342         return nlmsg_unicast(net->genl_sock, skb, portid);
 343 }
 344
 345 /**
 346  * genlmsg_reply - reply to a request
 347  * @skb: netlink message to be sent back
 348  * @info: receiver information
 349  */
 350 static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info)
 351 {
 352         return genlmsg_unicast(genl_info_net(info), skb, info->snd_portid);
 353 }
 354
 355 /**
 356  * gennlmsg_data - head of message payload
 357  * @gnlh: genetlink message header
 358  */
 359 static inline void *genlmsg_data(const struct genlmsghdr *gnlh)
 360 {
 361         return ((unsigned char *) gnlh + GENL_HDRLEN);
 362 }
 363
 364 /**
 365  * genlmsg_len - length of message payload
 366  * @gnlh: genetlink message header
 367  */
 368 static inline int genlmsg_len(const struct genlmsghdr *gnlh)
 369 {
 370         struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh -
 371                                                         NLMSG_HDRLEN);
 372         return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
 373 }
 374
 375 /**
 376  * genlmsg_msg_size - length of genetlink message not including padding
 377  * @payload: length of message payload
 378  */
 379 static inline int genlmsg_msg_size(int payload)
 380 {
 381         return GENL_HDRLEN + payload;
 382 }
 383
 384 /**
 385  * genlmsg_total_size - length of genetlink message including padding
 386  * @payload: length of message payload
 387  */
 388 static inline int genlmsg_total_size(int payload)
 389 {
 390         return NLMSG_ALIGN(genlmsg_msg_size(payload));
 391 }
 392
 393 /**
 394  * genlmsg_new - Allocate a new generic netlink message
 395  * @payload: size of the message payload
 396  * @flags: the type of memory to allocate.
 397  */
 398 static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
 399 {
 400         return nlmsg_new(genlmsg_total_size(payload), flags);
 401 }
 402
 403 /**
 404  * genl_set_err - report error to genetlink broadcast listeners
 405  * @family: the generic netlink family
 406  * @net: the network namespace to report the error to
 407  * @portid: the PORTID of a process that we want to skip (if any)
 408  * @group: the broadcast group that will notice the error
 409  *      (this is the offset of the multicast group in the groups array)
 410  * @code: error code, must be negative (as usual in kernelspace)
 411  *
 412  * This function returns the number of broadcast listeners that have set the
 413  * NETLINK_RECV_NO_ENOBUFS socket option.
 414  */
 415 static inline int genl_set_err(struct genl_family *family, struct net *net,
 416                                u32 portid, u32 group, int code)
 417 {
 418         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 419                 return -EINVAL;
 420         group = family->mcgrp_offset + group;
 421         return netlink_set_err(net->genl_sock, portid, group, code);
 422 }
 423
 424 static inline int genl_has_listeners(struct genl_family *family,
 425                                      struct net *net, unsigned int group)
 426 {
 427         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 428                 return -EINVAL;
 429         group = family->mcgrp_offset + group;
 430         return netlink_has_listeners(net->genl_sock, group);
 431 }
 432 #endif  /* __NET_GENERIC_NETLINK_H */