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