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  * @pre_doit: called before an operation's doit callback, it may
  31  *      do additional, common, filtering and return an error
  32  * @post_doit: called after an operation's doit callback, it may
  33  *      undo operations done by pre_doit, for example release locks
  34  * @attrbuf: buffer to store parsed attributes
  35  * @family_list: family list
  36  * @mcgrps: multicast groups used by this family (private)
  37  * @n_mcgrps: number of multicast groups (private)
  38  * @mcgrp_offset: starting number of multicast group IDs in this family
  39  * @ops: the operations supported by this family (private)
  40  * @n_ops: number of operations supported by this family (private)
  41  */
  42 struct genl_family {
  43         unsigned int            id;
  44         unsigned int            hdrsize;
  45         char                    name[GENL_NAMSIZ];
  46         unsigned int            version;
  47         unsigned int            maxattr;
  48         bool                    netnsok;
  49         bool                    parallel_ops;
  50         int                     (*pre_doit)(const struct genl_ops *ops,
  51                                             struct sk_buff *skb,
  52                                             struct genl_info *info);
  53         void                    (*post_doit)(const struct genl_ops *ops,
  54                                              struct sk_buff *skb,
  55                                              struct genl_info *info);
  56         struct nlattr **        attrbuf;        /* private */
  57         const struct genl_ops * ops;            /* private */
  58         const struct genl_multicast_group *mcgrps; /* private */
  59         unsigned int            n_ops;          /* private */
  60         unsigned int            n_mcgrps;       /* private */
  61         unsigned int            mcgrp_offset;   /* private */
  62         struct list_head        family_list;    /* private */
  63         struct module           *module;
  64 };
  65
  66 /**
  67  * struct genl_info - receiving information
  68  * @snd_seq: sending sequence number
  69  * @snd_portid: netlink portid of sender
  70  * @nlhdr: netlink message header
  71  * @genlhdr: generic netlink message header
  72  * @userhdr: user specific header
  73  * @attrs: netlink attributes
  74  * @_net: network namespace
  75  * @user_ptr: user pointers
  76  * @dst_sk: destination socket
  77  */
  78 struct genl_info {
  79         u32                     snd_seq;
  80         u32                     snd_portid;
  81         struct nlmsghdr *       nlhdr;
  82         struct genlmsghdr *     genlhdr;
  83         void *                  userhdr;
  84         struct nlattr **        attrs;
  85 #ifdef CONFIG_NET_NS
  86         struct net *            _net;
  87 #endif
  88         void *                  user_ptr[2];
  89         struct sock *           dst_sk;
  90 };
  91
  92 static inline struct net *genl_info_net(struct genl_info *info)
  93 {
  94         return read_pnet(&info->_net);
  95 }
  96
  97 static inline void genl_info_net_set(struct genl_info *info, struct net *net)
  98 {
  99         write_pnet(&info->_net, net);
 100 }
 101
 102 /**
 103  * struct genl_ops - generic netlink operations
 104  * @cmd: command identifier
 105  * @internal_flags: flags used by the family
 106  * @flags: flags
 107  * @policy: attribute validation policy
 108  * @doit: standard command callback
 109  * @dumpit: callback for dumpers
 110  * @done: completion callback for dumps
 111  * @ops_list: operations list
 112  */
 113 struct genl_ops {
 114         const struct nla_policy *policy;
 115         int                    (*doit)(struct sk_buff *skb,
 116                                        struct genl_info *info);
 117         int                    (*dumpit)(struct sk_buff *skb,
 118                                          struct netlink_callback *cb);
 119         int                    (*done)(struct netlink_callback *cb);
 120         u8                      cmd;
 121         u8                      internal_flags;
 122         u8                      flags;
 123 };
 124
 125 int __genl_register_family(struct genl_family *family);
 126
 127 static inline int genl_register_family(struct genl_family *family)
 128 {
 129         family->module = THIS_MODULE;
 130         return __genl_register_family(family);
 131 }
 132
 133 /**
 134  * genl_register_family_with_ops - register a generic netlink family with ops
 135  * @family: generic netlink family
 136  * @ops: operations to be registered
 137  * @n_ops: number of elements to register
 138  *
 139  * Registers the specified family and operations from the specified table.
 140  * Only one family may be registered with the same family name or identifier.
 141  *
 142  * The family id may equal GENL_ID_GENERATE causing an unique id to
 143  * be automatically generated and assigned.
 144  *
 145  * Either a doit or dumpit callback must be specified for every registered
 146  * operation or the function will fail. Only one operation structure per
 147  * command identifier may be registered.
 148  *
 149  * See include/net/genetlink.h for more documenation on the operations
 150  * structure.
 151  *
 152  * Return 0 on success or a negative error code.
 153  */
 154 static inline int
 155 _genl_register_family_with_ops_grps(struct genl_family *family,
 156                                     const struct genl_ops *ops, size_t n_ops,
 157                                     const struct genl_multicast_group *mcgrps,
 158                                     size_t n_mcgrps)
 159 {
 160         family->module = THIS_MODULE;
 161         family->ops = ops;
 162         family->n_ops = n_ops;
 163         family->mcgrps = mcgrps;
 164         family->n_mcgrps = n_mcgrps;
 165         return __genl_register_family(family);
 166 }
 167
 168 #define genl_register_family_with_ops(family, ops)                      \
 169         _genl_register_family_with_ops_grps((family),                   \
 170                                             (ops), ARRAY_SIZE(ops),     \
 171                                             NULL, 0)
 172 #define genl_register_family_with_ops_groups(family, ops, grps) \
 173         _genl_register_family_with_ops_grps((family),                   \
 174                                             (ops), ARRAY_SIZE(ops),     \
 175                                             (grps), ARRAY_SIZE(grps))
 176
 177 int genl_unregister_family(struct genl_family *family);
 178 void genl_notify(struct genl_family *family,
 179                  struct sk_buff *skb, struct net *net, u32 portid,
 180                  u32 group, struct nlmsghdr *nlh, gfp_t flags);
 181
 182 struct sk_buff *genlmsg_new_unicast(size_t payload, struct genl_info *info,
 183                                     gfp_t flags);
 184 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 185                   struct genl_family *family, int flags, u8 cmd);
 186
 187 /**
 188  * genlmsg_nlhdr - Obtain netlink header from user specified header
 189  * @user_hdr: user header as returned from genlmsg_put()
 190  * @family: generic netlink family
 191  *
 192  * Returns pointer to netlink header.
 193  */
 194 static inline struct nlmsghdr *genlmsg_nlhdr(void *user_hdr,
 195                                              struct genl_family *family)
 196 {
 197         return (struct nlmsghdr *)((char *)user_hdr -
 198                                    family->hdrsize -
 199                                    GENL_HDRLEN -
 200                                    NLMSG_HDRLEN);
 201 }
 202
 203 /**
 204  * genl_dump_check_consistent - check if sequence is consistent and advertise if not
 205  * @cb: netlink callback structure that stores the sequence number
 206  * @user_hdr: user header as returned from genlmsg_put()
 207  * @family: generic netlink family
 208  *
 209  * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it
 210  * simpler to use with generic netlink.
 211  */
 212 static inline void genl_dump_check_consistent(struct netlink_callback *cb,
 213                                               void *user_hdr,
 214                                               struct genl_family *family)
 215 {
 216         nl_dump_check_consistent(cb, genlmsg_nlhdr(user_hdr, family));
 217 }
 218
 219 /**
 220  * genlmsg_put_reply - Add generic netlink header to a reply message
 221  * @skb: socket buffer holding the message
 222  * @info: receiver info
 223  * @family: generic netlink family
 224  * @flags: netlink message flags
 225  * @cmd: generic netlink command
 226  *
 227  * Returns pointer to user specific header
 228  */
 229 static inline void *genlmsg_put_reply(struct sk_buff *skb,
 230                                       struct genl_info *info,
 231                                       struct genl_family *family,
 232                                       int flags, u8 cmd)
 233 {
 234         return genlmsg_put(skb, info->snd_portid, info->snd_seq, family,
 235                            flags, cmd);
 236 }
 237
 238 /**
 239  * genlmsg_end - Finalize a generic netlink message
 240  * @skb: socket buffer the message is stored in
 241  * @hdr: user specific header
 242  */
 243 static inline int genlmsg_end(struct sk_buff *skb, void *hdr)
 244 {
 245         return nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
 246 }
 247
 248 /**
 249  * genlmsg_cancel - Cancel construction of a generic netlink message
 250  * @skb: socket buffer the message is stored in
 251  * @hdr: generic netlink message header
 252  */
 253 static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr)
 254 {
 255         if (hdr)
 256                 nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
 257 }
 258
 259 /**
 260  * genlmsg_multicast_netns - multicast a netlink message to a specific netns
 261  * @family: the generic netlink family
 262  * @net: the net namespace
 263  * @skb: netlink message as socket buffer
 264  * @portid: own netlink portid to avoid sending to yourself
 265  * @group: offset of multicast group in groups array
 266  * @flags: allocation flags
 267  */
 268 static inline int genlmsg_multicast_netns(struct genl_family *family,
 269                                           struct net *net, struct sk_buff *skb,
 270                                           u32 portid, unsigned int group, gfp_t flags)
 271 {
 272         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 273                 return -EINVAL;
 274         group = family->mcgrp_offset + group;
 275         return nlmsg_multicast(net->genl_sock, skb, portid, group, flags);
 276 }
 277
 278 /**
 279  * genlmsg_multicast - multicast a netlink message to the default netns
 280  * @family: the generic netlink family
 281  * @skb: netlink message as socket buffer
 282  * @portid: own netlink portid to avoid sending to yourself
 283  * @group: offset of multicast group in groups array
 284  * @flags: allocation flags
 285  */
 286 static inline int genlmsg_multicast(struct genl_family *family,
 287                                     struct sk_buff *skb, u32 portid,
 288                                     unsigned int group, gfp_t flags)
 289 {
 290         return genlmsg_multicast_netns(family, &init_net, skb,
 291                                        portid, group, flags);
 292 }
 293
 294 /**
 295  * genlmsg_multicast_allns - multicast a netlink message to all net namespaces
 296  * @family: the generic netlink family
 297  * @skb: netlink message as socket buffer
 298  * @portid: own netlink portid to avoid sending to yourself
 299  * @group: offset of multicast group in groups array
 300  * @flags: allocation flags
 301  *
 302  * This function must hold the RTNL or rcu_read_lock().
 303  */
 304 int genlmsg_multicast_allns(struct genl_family *family,
 305                             struct sk_buff *skb, u32 portid,
 306                             unsigned int group, gfp_t flags);
 307
 308 /**
 309  * genlmsg_unicast - unicast a netlink message
 310  * @skb: netlink message as socket buffer
 311  * @portid: netlink portid of the destination socket
 312  */
 313 static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid)
 314 {
 315         return nlmsg_unicast(net->genl_sock, skb, portid);
 316 }
 317
 318 /**
 319  * genlmsg_reply - reply to a request
 320  * @skb: netlink message to be sent back
 321  * @info: receiver information
 322  */
 323 static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info)
 324 {
 325         return genlmsg_unicast(genl_info_net(info), skb, info->snd_portid);
 326 }
 327
 328 /**
 329  * gennlmsg_data - head of message payload
 330  * @gnlh: genetlink message header
 331  */
 332 static inline void *genlmsg_data(const struct genlmsghdr *gnlh)
 333 {
 334         return ((unsigned char *) gnlh + GENL_HDRLEN);
 335 }
 336
 337 /**
 338  * genlmsg_len - length of message payload
 339  * @gnlh: genetlink message header
 340  */
 341 static inline int genlmsg_len(const struct genlmsghdr *gnlh)
 342 {
 343         struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh -
 344                                                         NLMSG_HDRLEN);
 345         return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
 346 }
 347
 348 /**
 349  * genlmsg_msg_size - length of genetlink message not including padding
 350  * @payload: length of message payload
 351  */
 352 static inline int genlmsg_msg_size(int payload)
 353 {
 354         return GENL_HDRLEN + payload;
 355 }
 356
 357 /**
 358  * genlmsg_total_size - length of genetlink message including padding
 359  * @payload: length of message payload
 360  */
 361 static inline int genlmsg_total_size(int payload)
 362 {
 363         return NLMSG_ALIGN(genlmsg_msg_size(payload));
 364 }
 365
 366 /**
 367  * genlmsg_new - Allocate a new generic netlink message
 368  * @payload: size of the message payload
 369  * @flags: the type of memory to allocate.
 370  */
 371 static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
 372 {
 373         return nlmsg_new(genlmsg_total_size(payload), flags);
 374 }
 375
 376 /**
 377  * genl_set_err - report error to genetlink broadcast listeners
 378  * @family: the generic netlink family
 379  * @net: the network namespace to report the error to
 380  * @portid: the PORTID of a process that we want to skip (if any)
 381  * @group: the broadcast group that will notice the error
 382  *      (this is the offset of the multicast group in the groups array)
 383  * @code: error code, must be negative (as usual in kernelspace)
 384  *
 385  * This function returns the number of broadcast listeners that have set the
 386  * NETLINK_RECV_NO_ENOBUFS socket option.
 387  */
 388 static inline int genl_set_err(struct genl_family *family, struct net *net,
 389                                u32 portid, u32 group, int code)
 390 {
 391         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 392                 return -EINVAL;
 393         group = family->mcgrp_offset + group;
 394         return netlink_set_err(net->genl_sock, portid, group, code);
 395 }
 396
 397 #endif  /* __NET_GENERIC_NETLINK_H */