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