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 identifier (private)
  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 (private)
  43  * @mcgrps: multicast groups used by this family
  44  * @n_mcgrps: number of multicast groups
  45  * @mcgrp_offset: starting number of multicast group IDs in this family
  46  *      (private)
  47  * @ops: the operations supported by this family
  48  * @n_ops: number of operations supported by this family
  49  */
  50 struct genl_family {
  51         int                     id;             /* private */
  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;
  68         const struct genl_multicast_group *mcgrps;
  69         unsigned int            n_ops;
  70         unsigned int            n_mcgrps;
  71         unsigned int            mcgrp_offset;   /* private */
  72         struct module           *module;
  73 };
  74
  75 struct nlattr **genl_family_attrbuf(const struct genl_family *family);
  76
  77 /**
  78  * struct genl_info - receiving information
  79  * @snd_seq: sending sequence number
  80  * @snd_portid: netlink portid of sender
  81  * @nlhdr: netlink message header
  82  * @genlhdr: generic netlink message header
  83  * @userhdr: user specific header
  84  * @attrs: netlink attributes
  85  * @_net: network namespace
  86  * @user_ptr: user pointers
  87  * @extack: extended ACK report struct
  88  */
  89 struct genl_info {
  90         u32                     snd_seq;
  91         u32                     snd_portid;
  92         struct nlmsghdr *       nlhdr;
  93         struct genlmsghdr *     genlhdr;
  94         void *                  userhdr;
  95         struct nlattr **        attrs;
  96         possible_net_t          _net;
  97         void *                  user_ptr[2];
  98         struct netlink_ext_ack *extack;
  99 };
 100
 101 static inline struct net *genl_info_net(struct genl_info *info)
 102 {
 103         return read_pnet(&info->_net);
 104 }
 105
 106 static inline void genl_info_net_set(struct genl_info *info, struct net *net)
 107 {
 108         write_pnet(&info->_net, net);
 109 }
 110
 111 #define GENL_SET_ERR_MSG(info, msg) NL_SET_ERR_MSG((info)->extack, msg)
 112
 113 static inline int genl_err_attr(struct genl_info *info, int err,
 114                                 struct nlattr *attr)
 115 {
 116         info->extack->bad_attr = attr;
 117
 118         return err;
 119 }
 120
 121 /**
 122  * struct genl_ops - generic netlink operations
 123  * @cmd: command identifier
 124  * @internal_flags: flags used by the family
 125  * @flags: flags
 126  * @policy: attribute validation policy
 127  * @doit: standard command callback
 128  * @start: start callback for dumps
 129  * @dumpit: callback for dumpers
 130  * @done: completion callback for dumps
 131  */
 132 struct genl_ops {
 133         const struct nla_policy *policy;
 134         int                    (*doit)(struct sk_buff *skb,
 135                                        struct genl_info *info);
 136         int                    (*start)(struct netlink_callback *cb);
 137         int                    (*dumpit)(struct sk_buff *skb,
 138                                          struct netlink_callback *cb);
 139         int                    (*done)(struct netlink_callback *cb);
 140         u8                      cmd;
 141         u8                      internal_flags;
 142         u8                      flags;
 143 };
 144
 145 int genl_register_family(struct genl_family *family);
 146 int genl_unregister_family(const struct genl_family *family);
 147 void genl_notify(const struct genl_family *family, struct sk_buff *skb,
 148                  struct genl_info *info, u32 group, gfp_t flags);
 149
 150 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 151                   const struct genl_family *family, int flags, u8 cmd);
 152
 153 /**
 154  * genlmsg_nlhdr - Obtain netlink header from user specified header
 155  * @user_hdr: user header as returned from genlmsg_put()
 156  * @family: generic netlink family
 157  *
 158  * Returns pointer to netlink header.
 159  */
 160 static inline struct nlmsghdr *
 161 genlmsg_nlhdr(void *user_hdr, const struct genl_family *family)
 162 {
 163         return (struct nlmsghdr *)((char *)user_hdr -
 164                                    family->hdrsize -
 165                                    GENL_HDRLEN -
 166                                    NLMSG_HDRLEN);
 167 }
 168
 169 /**
 170  * genlmsg_parse - parse attributes of a genetlink message
 171  * @nlh: netlink message header
 172  * @family: genetlink message family
 173  * @tb: destination array with maxtype+1 elements
 174  * @maxtype: maximum attribute type to be expected
 175  * @policy: validation policy
 176  * @extack: extended ACK report struct
 177  */
 178 static inline int genlmsg_parse(const struct nlmsghdr *nlh,
 179                                 const struct genl_family *family,
 180                                 struct nlattr *tb[], int maxtype,
 181                                 const struct nla_policy *policy,
 182                                 struct netlink_ext_ack *extack)
 183 {
 184         return nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype,
 185                            policy, extack);
 186 }
 187
 188 /**
 189  * genl_dump_check_consistent - check if sequence is consistent and advertise if not
 190  * @cb: netlink callback structure that stores the sequence number
 191  * @user_hdr: user header as returned from genlmsg_put()
 192  * @family: generic netlink family
 193  *
 194  * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it
 195  * simpler to use with generic netlink.
 196  */
 197 static inline void genl_dump_check_consistent(struct netlink_callback *cb,
 198                                               void *user_hdr,
 199                                               const struct genl_family *family)
 200 {
 201         nl_dump_check_consistent(cb, genlmsg_nlhdr(user_hdr, family));
 202 }
 203
 204 /**
 205  * genlmsg_put_reply - Add generic netlink header to a reply message
 206  * @skb: socket buffer holding the message
 207  * @info: receiver info
 208  * @family: generic netlink family
 209  * @flags: netlink message flags
 210  * @cmd: generic netlink command
 211  *
 212  * Returns pointer to user specific header
 213  */
 214 static inline void *genlmsg_put_reply(struct sk_buff *skb,
 215                                       struct genl_info *info,
 216                                       const struct genl_family *family,
 217                                       int flags, u8 cmd)
 218 {
 219         return genlmsg_put(skb, info->snd_portid, info->snd_seq, family,
 220                            flags, cmd);
 221 }
 222
 223 /**
 224  * genlmsg_end - Finalize a generic netlink message
 225  * @skb: socket buffer the message is stored in
 226  * @hdr: user specific header
 227  */
 228 static inline void genlmsg_end(struct sk_buff *skb, void *hdr)
 229 {
 230         nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
 231 }
 232
 233 /**
 234  * genlmsg_cancel - Cancel construction of a generic netlink message
 235  * @skb: socket buffer the message is stored in
 236  * @hdr: generic netlink message header
 237  */
 238 static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr)
 239 {
 240         if (hdr)
 241                 nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
 242 }
 243
 244 /**
 245  * genlmsg_multicast_netns - multicast a netlink message to a specific netns
 246  * @family: the generic netlink family
 247  * @net: the net namespace
 248  * @skb: netlink message as socket buffer
 249  * @portid: own netlink portid to avoid sending to yourself
 250  * @group: offset of multicast group in groups array
 251  * @flags: allocation flags
 252  */
 253 static inline int genlmsg_multicast_netns(const struct genl_family *family,
 254                                           struct net *net, struct sk_buff *skb,
 255                                           u32 portid, unsigned int group, gfp_t flags)
 256 {
 257         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 258                 return -EINVAL;
 259         group = family->mcgrp_offset + group;
 260         return nlmsg_multicast(net->genl_sock, skb, portid, group, flags);
 261 }
 262
 263 /**
 264  * genlmsg_multicast - multicast a netlink message to the default netns
 265  * @family: the generic netlink family
 266  * @skb: netlink message as socket buffer
 267  * @portid: own netlink portid to avoid sending to yourself
 268  * @group: offset of multicast group in groups array
 269  * @flags: allocation flags
 270  */
 271 static inline int genlmsg_multicast(const struct genl_family *family,
 272                                     struct sk_buff *skb, u32 portid,
 273                                     unsigned int group, gfp_t flags)
 274 {
 275         return genlmsg_multicast_netns(family, &init_net, skb,
 276                                        portid, group, flags);
 277 }
 278
 279 /**
 280  * genlmsg_multicast_allns - multicast a netlink message to all net namespaces
 281  * @family: the generic netlink family
 282  * @skb: netlink message as socket buffer
 283  * @portid: own netlink portid to avoid sending to yourself
 284  * @group: offset of multicast group in groups array
 285  * @flags: allocation flags
 286  *
 287  * This function must hold the RTNL or rcu_read_lock().
 288  */
 289 int genlmsg_multicast_allns(const struct genl_family *family,
 290                             struct sk_buff *skb, u32 portid,
 291                             unsigned int group, gfp_t flags);
 292
 293 /**
 294  * genlmsg_unicast - unicast a netlink message
 295  * @skb: netlink message as socket buffer
 296  * @portid: netlink portid of the destination socket
 297  */
 298 static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid)
 299 {
 300         return nlmsg_unicast(net->genl_sock, skb, portid);
 301 }
 302
 303 /**
 304  * genlmsg_reply - reply to a request
 305  * @skb: netlink message to be sent back
 306  * @info: receiver information
 307  */
 308 static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info)
 309 {
 310         return genlmsg_unicast(genl_info_net(info), skb, info->snd_portid);
 311 }
 312
 313 /**
 314  * gennlmsg_data - head of message payload
 315  * @gnlh: genetlink message header
 316  */
 317 static inline void *genlmsg_data(const struct genlmsghdr *gnlh)
 318 {
 319         return ((unsigned char *) gnlh + GENL_HDRLEN);
 320 }
 321
 322 /**
 323  * genlmsg_len - length of message payload
 324  * @gnlh: genetlink message header
 325  */
 326 static inline int genlmsg_len(const struct genlmsghdr *gnlh)
 327 {
 328         struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh -
 329                                                         NLMSG_HDRLEN);
 330         return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
 331 }
 332
 333 /**
 334  * genlmsg_msg_size - length of genetlink message not including padding
 335  * @payload: length of message payload
 336  */
 337 static inline int genlmsg_msg_size(int payload)
 338 {
 339         return GENL_HDRLEN + payload;
 340 }
 341
 342 /**
 343  * genlmsg_total_size - length of genetlink message including padding
 344  * @payload: length of message payload
 345  */
 346 static inline int genlmsg_total_size(int payload)
 347 {
 348         return NLMSG_ALIGN(genlmsg_msg_size(payload));
 349 }
 350
 351 /**
 352  * genlmsg_new - Allocate a new generic netlink message
 353  * @payload: size of the message payload
 354  * @flags: the type of memory to allocate.
 355  */
 356 static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
 357 {
 358         return nlmsg_new(genlmsg_total_size(payload), flags);
 359 }
 360
 361 /**
 362  * genl_set_err - report error to genetlink broadcast listeners
 363  * @family: the generic netlink family
 364  * @net: the network namespace to report the error to
 365  * @portid: the PORTID of a process that we want to skip (if any)
 366  * @group: the broadcast group that will notice the error
 367  *      (this is the offset of the multicast group in the groups array)
 368  * @code: error code, must be negative (as usual in kernelspace)
 369  *
 370  * This function returns the number of broadcast listeners that have set the
 371  * NETLINK_RECV_NO_ENOBUFS socket option.
 372  */
 373 static inline int genl_set_err(const struct genl_family *family,
 374                                struct net *net, u32 portid,
 375                                u32 group, int code)
 376 {
 377         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 378                 return -EINVAL;
 379         group = family->mcgrp_offset + group;
 380         return netlink_set_err(net->genl_sock, portid, group, code);
 381 }
 382
 383 static inline int genl_has_listeners(const struct genl_family *family,
 384                                      struct net *net, unsigned int group)
 385 {
 386         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 387                 return -EINVAL;
 388         group = family->mcgrp_offset + group;
 389         return netlink_has_listeners(net->genl_sock, group);
 390 }
 391 #endif  /* __NET_GENERIC_NETLINK_H */