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