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  * @dumpit: callback for dumpers
 118  * @done: completion callback for dumps
 119  * @ops_list: operations list
 120  */
 121 struct genl_ops {
 122         const struct nla_policy *policy;
 123         int                    (*doit)(struct sk_buff *skb,
 124                                        struct genl_info *info);
 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,
 187                  struct sk_buff *skb, struct net *net, u32 portid,
 188                  u32 group, struct nlmsghdr *nlh, gfp_t flags);
 189
 190 struct sk_buff *genlmsg_new_unicast(size_t payload, struct genl_info *info,
 191                                     gfp_t flags);
 192 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 193                   struct genl_family *family, int flags, u8 cmd);
 194
 195 /**
 196  * genlmsg_nlhdr - Obtain netlink header from user specified header
 197  * @user_hdr: user header as returned from genlmsg_put()
 198  * @family: generic netlink family
 199  *
 200  * Returns pointer to netlink header.
 201  */
 202 static inline struct nlmsghdr *genlmsg_nlhdr(void *user_hdr,
 203                                              struct genl_family *family)
 204 {
 205         return (struct nlmsghdr *)((char *)user_hdr -
 206                                    family->hdrsize -
 207                                    GENL_HDRLEN -
 208                                    NLMSG_HDRLEN);
 209 }
 210
 211 /**
 212  * genlmsg_parse - parse attributes of a genetlink message
 213  * @nlh: netlink message header
 214  * @family: genetlink message family
 215  * @tb: destination array with maxtype+1 elements
 216  * @maxtype: maximum attribute type to be expected
 217  * @policy: validation policy
 218  * */
 219 static inline int genlmsg_parse(const struct nlmsghdr *nlh,
 220                                 const struct genl_family *family,
 221                                 struct nlattr *tb[], int maxtype,
 222                                 const struct nla_policy *policy)
 223 {
 224         return nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype,
 225                            policy);
 226 }
 227
 228 /**
 229  * genl_dump_check_consistent - check if sequence is consistent and advertise if not
 230  * @cb: netlink callback structure that stores the sequence number
 231  * @user_hdr: user header as returned from genlmsg_put()
 232  * @family: generic netlink family
 233  *
 234  * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it
 235  * simpler to use with generic netlink.
 236  */
 237 static inline void genl_dump_check_consistent(struct netlink_callback *cb,
 238                                               void *user_hdr,
 239                                               struct genl_family *family)
 240 {
 241         nl_dump_check_consistent(cb, genlmsg_nlhdr(user_hdr, family));
 242 }
 243
 244 /**
 245  * genlmsg_put_reply - Add generic netlink header to a reply message
 246  * @skb: socket buffer holding the message
 247  * @info: receiver info
 248  * @family: generic netlink family
 249  * @flags: netlink message flags
 250  * @cmd: generic netlink command
 251  *
 252  * Returns pointer to user specific header
 253  */
 254 static inline void *genlmsg_put_reply(struct sk_buff *skb,
 255                                       struct genl_info *info,
 256                                       struct genl_family *family,
 257                                       int flags, u8 cmd)
 258 {
 259         return genlmsg_put(skb, info->snd_portid, info->snd_seq, family,
 260                            flags, cmd);
 261 }
 262
 263 /**
 264  * genlmsg_end - Finalize a generic netlink message
 265  * @skb: socket buffer the message is stored in
 266  * @hdr: user specific header
 267  */
 268 static inline void genlmsg_end(struct sk_buff *skb, void *hdr)
 269 {
 270         nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
 271 }
 272
 273 /**
 274  * genlmsg_cancel - Cancel construction of a generic netlink message
 275  * @skb: socket buffer the message is stored in
 276  * @hdr: generic netlink message header
 277  */
 278 static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr)
 279 {
 280         if (hdr)
 281                 nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
 282 }
 283
 284 /**
 285  * genlmsg_multicast_netns - multicast a netlink message to a specific netns
 286  * @family: the generic netlink family
 287  * @net: the net namespace
 288  * @skb: netlink message as socket buffer
 289  * @portid: own netlink portid to avoid sending to yourself
 290  * @group: offset of multicast group in groups array
 291  * @flags: allocation flags
 292  */
 293 static inline int genlmsg_multicast_netns(struct genl_family *family,
 294                                           struct net *net, struct sk_buff *skb,
 295                                           u32 portid, unsigned int group, gfp_t flags)
 296 {
 297         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 298                 return -EINVAL;
 299         group = family->mcgrp_offset + group;
 300         return nlmsg_multicast(net->genl_sock, skb, portid, group, flags);
 301 }
 302
 303 /**
 304  * genlmsg_multicast - multicast a netlink message to the default netns
 305  * @family: the generic netlink family
 306  * @skb: netlink message as socket buffer
 307  * @portid: own netlink portid to avoid sending to yourself
 308  * @group: offset of multicast group in groups array
 309  * @flags: allocation flags
 310  */
 311 static inline int genlmsg_multicast(struct genl_family *family,
 312                                     struct sk_buff *skb, u32 portid,
 313                                     unsigned int group, gfp_t flags)
 314 {
 315         return genlmsg_multicast_netns(family, &init_net, skb,
 316                                        portid, group, flags);
 317 }
 318
 319 /**
 320  * genlmsg_multicast_allns - multicast a netlink message to all net namespaces
 321  * @family: the generic netlink family
 322  * @skb: netlink message as socket buffer
 323  * @portid: own netlink portid to avoid sending to yourself
 324  * @group: offset of multicast group in groups array
 325  * @flags: allocation flags
 326  *
 327  * This function must hold the RTNL or rcu_read_lock().
 328  */
 329 int genlmsg_multicast_allns(struct genl_family *family,
 330                             struct sk_buff *skb, u32 portid,
 331                             unsigned int group, gfp_t flags);
 332
 333 /**
 334  * genlmsg_unicast - unicast a netlink message
 335  * @skb: netlink message as socket buffer
 336  * @portid: netlink portid of the destination socket
 337  */
 338 static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid)
 339 {
 340         return nlmsg_unicast(net->genl_sock, skb, portid);
 341 }
 342
 343 /**
 344  * genlmsg_reply - reply to a request
 345  * @skb: netlink message to be sent back
 346  * @info: receiver information
 347  */
 348 static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info)
 349 {
 350         return genlmsg_unicast(genl_info_net(info), skb, info->snd_portid);
 351 }
 352
 353 /**
 354  * gennlmsg_data - head of message payload
 355  * @gnlh: genetlink message header
 356  */
 357 static inline void *genlmsg_data(const struct genlmsghdr *gnlh)
 358 {
 359         return ((unsigned char *) gnlh + GENL_HDRLEN);
 360 }
 361
 362 /**
 363  * genlmsg_len - length of message payload
 364  * @gnlh: genetlink message header
 365  */
 366 static inline int genlmsg_len(const struct genlmsghdr *gnlh)
 367 {
 368         struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh -
 369                                                         NLMSG_HDRLEN);
 370         return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
 371 }
 372
 373 /**
 374  * genlmsg_msg_size - length of genetlink message not including padding
 375  * @payload: length of message payload
 376  */
 377 static inline int genlmsg_msg_size(int payload)
 378 {
 379         return GENL_HDRLEN + payload;
 380 }
 381
 382 /**
 383  * genlmsg_total_size - length of genetlink message including padding
 384  * @payload: length of message payload
 385  */
 386 static inline int genlmsg_total_size(int payload)
 387 {
 388         return NLMSG_ALIGN(genlmsg_msg_size(payload));
 389 }
 390
 391 /**
 392  * genlmsg_new - Allocate a new generic netlink message
 393  * @payload: size of the message payload
 394  * @flags: the type of memory to allocate.
 395  */
 396 static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
 397 {
 398         return nlmsg_new(genlmsg_total_size(payload), flags);
 399 }
 400
 401 /**
 402  * genl_set_err - report error to genetlink broadcast listeners
 403  * @family: the generic netlink family
 404  * @net: the network namespace to report the error to
 405  * @portid: the PORTID of a process that we want to skip (if any)
 406  * @group: the broadcast group that will notice the error
 407  *      (this is the offset of the multicast group in the groups array)
 408  * @code: error code, must be negative (as usual in kernelspace)
 409  *
 410  * This function returns the number of broadcast listeners that have set the
 411  * NETLINK_RECV_NO_ENOBUFS socket option.
 412  */
 413 static inline int genl_set_err(struct genl_family *family, struct net *net,
 414                                u32 portid, u32 group, int code)
 415 {
 416         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 417                 return -EINVAL;
 418         group = family->mcgrp_offset + group;
 419         return netlink_set_err(net->genl_sock, portid, group, code);
 420 }
 421
 422 static inline int genl_has_listeners(struct genl_family *family,
 423                                      struct net *net, unsigned int group)
 424 {
 425         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 426                 return -EINVAL;
 427         group = family->mcgrp_offset + group;
 428         return netlink_has_listeners(net->genl_sock, group);
 429 }
 430 #endif  /* __NET_GENERIC_NETLINK_H */