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  * genl_dump_check_consistent - check if sequence is consistent and advertise if not
 215  * @cb: netlink callback structure that stores the sequence number
 216  * @user_hdr: user header as returned from genlmsg_put()
 217  * @family: generic netlink family
 218  *
 219  * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it
 220  * simpler to use with generic netlink.
 221  */
 222 static inline void genl_dump_check_consistent(struct netlink_callback *cb,
 223                                               void *user_hdr,
 224                                               struct genl_family *family)
 225 {
 226         nl_dump_check_consistent(cb, genlmsg_nlhdr(user_hdr, family));
 227 }
 228
 229 /**
 230  * genlmsg_put_reply - Add generic netlink header to a reply message
 231  * @skb: socket buffer holding the message
 232  * @info: receiver info
 233  * @family: generic netlink family
 234  * @flags: netlink message flags
 235  * @cmd: generic netlink command
 236  *
 237  * Returns pointer to user specific header
 238  */
 239 static inline void *genlmsg_put_reply(struct sk_buff *skb,
 240                                       struct genl_info *info,
 241                                       struct genl_family *family,
 242                                       int flags, u8 cmd)
 243 {
 244         return genlmsg_put(skb, info->snd_portid, info->snd_seq, family,
 245                            flags, cmd);
 246 }
 247
 248 /**
 249  * genlmsg_end - Finalize a generic netlink message
 250  * @skb: socket buffer the message is stored in
 251  * @hdr: user specific header
 252  */
 253 static inline int genlmsg_end(struct sk_buff *skb, void *hdr)
 254 {
 255         return nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
 256 }
 257
 258 /**
 259  * genlmsg_cancel - Cancel construction of a generic netlink message
 260  * @skb: socket buffer the message is stored in
 261  * @hdr: generic netlink message header
 262  */
 263 static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr)
 264 {
 265         if (hdr)
 266                 nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
 267 }
 268
 269 /**
 270  * genlmsg_multicast_netns - multicast a netlink message to a specific netns
 271  * @family: the generic netlink family
 272  * @net: the net namespace
 273  * @skb: netlink message as socket buffer
 274  * @portid: own netlink portid to avoid sending to yourself
 275  * @group: offset of multicast group in groups array
 276  * @flags: allocation flags
 277  */
 278 static inline int genlmsg_multicast_netns(struct genl_family *family,
 279                                           struct net *net, struct sk_buff *skb,
 280                                           u32 portid, unsigned int group, gfp_t flags)
 281 {
 282         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 283                 return -EINVAL;
 284         group = family->mcgrp_offset + group;
 285         return nlmsg_multicast(net->genl_sock, skb, portid, group, flags);
 286 }
 287
 288 /**
 289  * genlmsg_multicast - multicast a netlink message to the default netns
 290  * @family: the generic netlink family
 291  * @skb: netlink message as socket buffer
 292  * @portid: own netlink portid to avoid sending to yourself
 293  * @group: offset of multicast group in groups array
 294  * @flags: allocation flags
 295  */
 296 static inline int genlmsg_multicast(struct genl_family *family,
 297                                     struct sk_buff *skb, u32 portid,
 298                                     unsigned int group, gfp_t flags)
 299 {
 300         return genlmsg_multicast_netns(family, &init_net, skb,
 301                                        portid, group, flags);
 302 }
 303
 304 /**
 305  * genlmsg_multicast_allns - multicast a netlink message to all net namespaces
 306  * @family: the generic netlink family
 307  * @skb: netlink message as socket buffer
 308  * @portid: own netlink portid to avoid sending to yourself
 309  * @group: offset of multicast group in groups array
 310  * @flags: allocation flags
 311  *
 312  * This function must hold the RTNL or rcu_read_lock().
 313  */
 314 int genlmsg_multicast_allns(struct genl_family *family,
 315                             struct sk_buff *skb, u32 portid,
 316                             unsigned int group, gfp_t flags);
 317
 318 /**
 319  * genlmsg_unicast - unicast a netlink message
 320  * @skb: netlink message as socket buffer
 321  * @portid: netlink portid of the destination socket
 322  */
 323 static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid)
 324 {
 325         return nlmsg_unicast(net->genl_sock, skb, portid);
 326 }
 327
 328 /**
 329  * genlmsg_reply - reply to a request
 330  * @skb: netlink message to be sent back
 331  * @info: receiver information
 332  */
 333 static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info)
 334 {
 335         return genlmsg_unicast(genl_info_net(info), skb, info->snd_portid);
 336 }
 337
 338 /**
 339  * gennlmsg_data - head of message payload
 340  * @gnlh: genetlink message header
 341  */
 342 static inline void *genlmsg_data(const struct genlmsghdr *gnlh)
 343 {
 344         return ((unsigned char *) gnlh + GENL_HDRLEN);
 345 }
 346
 347 /**
 348  * genlmsg_len - length of message payload
 349  * @gnlh: genetlink message header
 350  */
 351 static inline int genlmsg_len(const struct genlmsghdr *gnlh)
 352 {
 353         struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh -
 354                                                         NLMSG_HDRLEN);
 355         return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
 356 }
 357
 358 /**
 359  * genlmsg_msg_size - length of genetlink message not including padding
 360  * @payload: length of message payload
 361  */
 362 static inline int genlmsg_msg_size(int payload)
 363 {
 364         return GENL_HDRLEN + payload;
 365 }
 366
 367 /**
 368  * genlmsg_total_size - length of genetlink message including padding
 369  * @payload: length of message payload
 370  */
 371 static inline int genlmsg_total_size(int payload)
 372 {
 373         return NLMSG_ALIGN(genlmsg_msg_size(payload));
 374 }
 375
 376 /**
 377  * genlmsg_new - Allocate a new generic netlink message
 378  * @payload: size of the message payload
 379  * @flags: the type of memory to allocate.
 380  */
 381 static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
 382 {
 383         return nlmsg_new(genlmsg_total_size(payload), flags);
 384 }
 385
 386 /**
 387  * genl_set_err - report error to genetlink broadcast listeners
 388  * @family: the generic netlink family
 389  * @net: the network namespace to report the error to
 390  * @portid: the PORTID of a process that we want to skip (if any)
 391  * @group: the broadcast group that will notice the error
 392  *      (this is the offset of the multicast group in the groups array)
 393  * @code: error code, must be negative (as usual in kernelspace)
 394  *
 395  * This function returns the number of broadcast listeners that have set the
 396  * NETLINK_RECV_NO_ENOBUFS socket option.
 397  */
 398 static inline int genl_set_err(struct genl_family *family, struct net *net,
 399                                u32 portid, u32 group, int code)
 400 {
 401         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 402                 return -EINVAL;
 403         group = family->mcgrp_offset + group;
 404         return netlink_set_err(net->genl_sock, portid, group, code);
 405 }
 406
 407 static inline int genl_has_listeners(struct genl_family *family,
 408                                      struct net *net, unsigned int group)
 409 {
 410         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 411                 return -EINVAL;
 412         group = family->mcgrp_offset + group;
 413         return netlink_has_listeners(net->genl_sock, group);
 414 }
 415 #endif  /* __NET_GENERIC_NETLINK_H */