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         possible_net_t          _net;
  96         void *                  user_ptr[2];
  97         struct sock *           dst_sk;
  98 };
  99
 100 static inline struct net *genl_info_net(struct genl_info *info)
 101 {
 102         return read_pnet(&info->_net);
 103 }
 104
 105 static inline void genl_info_net_set(struct genl_info *info, struct net *net)
 106 {
 107         write_pnet(&info->_net, net);
 108 }
 109
 110 /**
 111  * struct genl_ops - generic netlink operations
 112  * @cmd: command identifier
 113  * @internal_flags: flags used by the family
 114  * @flags: flags
 115  * @policy: attribute validation policy
 116  * @doit: standard command callback
 117  * @start: start callback for dumps
 118  * @dumpit: callback for dumpers
 119  * @done: completion callback for dumps
 120  * @ops_list: operations list
 121  */
 122 struct genl_ops {
 123         const struct nla_policy *policy;
 124         int                    (*doit)(struct sk_buff *skb,
 125                                        struct genl_info *info);
 126         int                    (*start)(struct netlink_callback *cb);
 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, struct sk_buff *skb,
 189                  struct genl_info *info, u32 group, gfp_t flags);
 190
 191 struct sk_buff *genlmsg_new_unicast(size_t payload, struct genl_info *info,
 192                                     gfp_t flags);
 193 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 194                   struct genl_family *family, int flags, u8 cmd);
 195
 196 /**
 197  * genlmsg_nlhdr - Obtain netlink header from user specified header
 198  * @user_hdr: user header as returned from genlmsg_put()
 199  * @family: generic netlink family
 200  *
 201  * Returns pointer to netlink header.
 202  */
 203 static inline struct nlmsghdr *genlmsg_nlhdr(void *user_hdr,
 204                                              struct genl_family *family)
 205 {
 206         return (struct nlmsghdr *)((char *)user_hdr -
 207                                    family->hdrsize -
 208                                    GENL_HDRLEN -
 209                                    NLMSG_HDRLEN);
 210 }
 211
 212 /**
 213  * genlmsg_parse - parse attributes of a genetlink message
 214  * @nlh: netlink message header
 215  * @family: genetlink message family
 216  * @tb: destination array with maxtype+1 elements
 217  * @maxtype: maximum attribute type to be expected
 218  * @policy: validation policy
 219  * */
 220 static inline int genlmsg_parse(const struct nlmsghdr *nlh,
 221                                 const struct genl_family *family,
 222                                 struct nlattr *tb[], int maxtype,
 223                                 const struct nla_policy *policy)
 224 {
 225         return nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype,
 226                            policy);
 227 }
 228
 229 /**
 230  * genl_dump_check_consistent - check if sequence is consistent and advertise if not
 231  * @cb: netlink callback structure that stores the sequence number
 232  * @user_hdr: user header as returned from genlmsg_put()
 233  * @family: generic netlink family
 234  *
 235  * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it
 236  * simpler to use with generic netlink.
 237  */
 238 static inline void genl_dump_check_consistent(struct netlink_callback *cb,
 239                                               void *user_hdr,
 240                                               struct genl_family *family)
 241 {
 242         nl_dump_check_consistent(cb, genlmsg_nlhdr(user_hdr, family));
 243 }
 244
 245 /**
 246  * genlmsg_put_reply - Add generic netlink header to a reply message
 247  * @skb: socket buffer holding the message
 248  * @info: receiver info
 249  * @family: generic netlink family
 250  * @flags: netlink message flags
 251  * @cmd: generic netlink command
 252  *
 253  * Returns pointer to user specific header
 254  */
 255 static inline void *genlmsg_put_reply(struct sk_buff *skb,
 256                                       struct genl_info *info,
 257                                       struct genl_family *family,
 258                                       int flags, u8 cmd)
 259 {
 260         return genlmsg_put(skb, info->snd_portid, info->snd_seq, family,
 261                            flags, cmd);
 262 }
 263
 264 /**
 265  * genlmsg_end - Finalize a generic netlink message
 266  * @skb: socket buffer the message is stored in
 267  * @hdr: user specific header
 268  */
 269 static inline void genlmsg_end(struct sk_buff *skb, void *hdr)
 270 {
 271         nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
 272 }
 273
 274 /**
 275  * genlmsg_cancel - Cancel construction of a generic netlink message
 276  * @skb: socket buffer the message is stored in
 277  * @hdr: generic netlink message header
 278  */
 279 static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr)
 280 {
 281         if (hdr)
 282                 nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
 283 }
 284
 285 /**
 286  * genlmsg_multicast_netns - multicast a netlink message to a specific netns
 287  * @family: the generic netlink family
 288  * @net: the net namespace
 289  * @skb: netlink message as socket buffer
 290  * @portid: own netlink portid to avoid sending to yourself
 291  * @group: offset of multicast group in groups array
 292  * @flags: allocation flags
 293  */
 294 static inline int genlmsg_multicast_netns(struct genl_family *family,
 295                                           struct net *net, struct sk_buff *skb,
 296                                           u32 portid, unsigned int group, gfp_t flags)
 297 {
 298         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 299                 return -EINVAL;
 300         group = family->mcgrp_offset + group;
 301         return nlmsg_multicast(net->genl_sock, skb, portid, group, flags);
 302 }
 303
 304 /**
 305  * genlmsg_multicast - multicast a netlink message to the default netns
 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 static inline int genlmsg_multicast(struct genl_family *family,
 313                                     struct sk_buff *skb, u32 portid,
 314                                     unsigned int group, gfp_t flags)
 315 {
 316         return genlmsg_multicast_netns(family, &init_net, skb,
 317                                        portid, group, flags);
 318 }
 319
 320 /**
 321  * genlmsg_multicast_allns - multicast a netlink message to all net namespaces
 322  * @family: the generic netlink family
 323  * @skb: netlink message as socket buffer
 324  * @portid: own netlink portid to avoid sending to yourself
 325  * @group: offset of multicast group in groups array
 326  * @flags: allocation flags
 327  *
 328  * This function must hold the RTNL or rcu_read_lock().
 329  */
 330 int genlmsg_multicast_allns(struct genl_family *family,
 331                             struct sk_buff *skb, u32 portid,
 332                             unsigned int group, gfp_t flags);
 333
 334 /**
 335  * genlmsg_unicast - unicast a netlink message
 336  * @skb: netlink message as socket buffer
 337  * @portid: netlink portid of the destination socket
 338  */
 339 static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid)
 340 {
 341         return nlmsg_unicast(net->genl_sock, skb, portid);
 342 }
 343
 344 /**
 345  * genlmsg_reply - reply to a request
 346  * @skb: netlink message to be sent back
 347  * @info: receiver information
 348  */
 349 static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info)
 350 {
 351         return genlmsg_unicast(genl_info_net(info), skb, info->snd_portid);
 352 }
 353
 354 /**
 355  * gennlmsg_data - head of message payload
 356  * @gnlh: genetlink message header
 357  */
 358 static inline void *genlmsg_data(const struct genlmsghdr *gnlh)
 359 {
 360         return ((unsigned char *) gnlh + GENL_HDRLEN);
 361 }
 362
 363 /**
 364  * genlmsg_len - length of message payload
 365  * @gnlh: genetlink message header
 366  */
 367 static inline int genlmsg_len(const struct genlmsghdr *gnlh)
 368 {
 369         struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh -
 370                                                         NLMSG_HDRLEN);
 371         return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
 372 }
 373
 374 /**
 375  * genlmsg_msg_size - length of genetlink message not including padding
 376  * @payload: length of message payload
 377  */
 378 static inline int genlmsg_msg_size(int payload)
 379 {
 380         return GENL_HDRLEN + payload;
 381 }
 382
 383 /**
 384  * genlmsg_total_size - length of genetlink message including padding
 385  * @payload: length of message payload
 386  */
 387 static inline int genlmsg_total_size(int payload)
 388 {
 389         return NLMSG_ALIGN(genlmsg_msg_size(payload));
 390 }
 391
 392 /**
 393  * genlmsg_new - Allocate a new generic netlink message
 394  * @payload: size of the message payload
 395  * @flags: the type of memory to allocate.
 396  */
 397 static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
 398 {
 399         return nlmsg_new(genlmsg_total_size(payload), flags);
 400 }
 401
 402 /**
 403  * genl_set_err - report error to genetlink broadcast listeners
 404  * @family: the generic netlink family
 405  * @net: the network namespace to report the error to
 406  * @portid: the PORTID of a process that we want to skip (if any)
 407  * @group: the broadcast group that will notice the error
 408  *      (this is the offset of the multicast group in the groups array)
 409  * @code: error code, must be negative (as usual in kernelspace)
 410  *
 411  * This function returns the number of broadcast listeners that have set the
 412  * NETLINK_RECV_NO_ENOBUFS socket option.
 413  */
 414 static inline int genl_set_err(struct genl_family *family, struct net *net,
 415                                u32 portid, u32 group, int code)
 416 {
 417         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 418                 return -EINVAL;
 419         group = family->mcgrp_offset + group;
 420         return netlink_set_err(net->genl_sock, portid, group, code);
 421 }
 422
 423 static inline int genl_has_listeners(struct genl_family *family,
 424                                      struct net *net, unsigned int group)
 425 {
 426         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 427                 return -EINVAL;
 428         group = family->mcgrp_offset + group;
 429         return netlink_has_listeners(net->genl_sock, group);
 430 }
 431 #endif  /* __NET_GENERIC_NETLINK_H */