include/net/genetlink.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef __NET_GENERIC_NETLINK_H
   3 #define __NET_GENERIC_NETLINK_H
   4
   5 #include <linux/genetlink.h>
   6 #include <net/netlink.h>
   7 #include <net/net_namespace.h>
   8
   9 #define GENLMSG_DEFAULT_SIZE (NLMSG_DEFAULT_SIZE - GENL_HDRLEN)
  10
  11 /**
  12  * struct genl_multicast_group - generic netlink multicast group
  13  * @name: name of the multicast group, names are per-family
  14  */
  15 struct genl_multicast_group {
  16         char                    name[GENL_NAMSIZ];
  17 };
  18
  19 struct genl_ops;
  20 struct genl_info;
  21
  22 /**
  23  * struct genl_family - generic netlink family
  24  * @id: protocol family identifier (private)
  25  * @hdrsize: length of user specific header in bytes
  26  * @name: name of family
  27  * @version: protocol version
  28  * @maxattr: maximum number of attributes supported
  29  * @netnsok: set to true if the family can handle network
  30  *      namespaces and should be presented in all of them
  31  * @parallel_ops: operations can be called in parallel and aren't
  32  *      synchronized by the core genetlink code
  33  * @pre_doit: called before an operation's doit callback, it may
  34  *      do additional, common, filtering and return an error
  35  * @post_doit: called after an operation's doit callback, it may
  36  *      undo operations done by pre_doit, for example release locks
  37  * @mcast_bind: a socket bound to the given multicast group (which
  38  *      is given as the offset into the groups array)
  39  * @mcast_unbind: a socket was unbound from the given multicast group.
  40  *      Note that unbind() will not be called symmetrically if the
  41  *      generic netlink family is removed while there are still open
  42  *      sockets.
  43  * @attrbuf: buffer to store parsed attributes (private)
  44  * @mcgrps: multicast groups used by this family
  45  * @n_mcgrps: number of multicast groups
  46  * @mcgrp_offset: starting number of multicast group IDs in this family
  47  *      (private)
  48  * @ops: the operations supported by this family
  49  * @n_ops: number of operations supported by this family
  50  */
  51 struct genl_family {
  52         int                     id;             /* private */
  53         unsigned int            hdrsize;
  54         char                    name[GENL_NAMSIZ];
  55         unsigned int            version;
  56         unsigned int            maxattr;
  57         bool                    netnsok;
  58         bool                    parallel_ops;
  59         int                     (*pre_doit)(const struct genl_ops *ops,
  60                                             struct sk_buff *skb,
  61                                             struct genl_info *info);
  62         void                    (*post_doit)(const struct genl_ops *ops,
  63                                              struct sk_buff *skb,
  64                                              struct genl_info *info);
  65         int                     (*mcast_bind)(struct net *net, int group);
  66         void                    (*mcast_unbind)(struct net *net, int group);
  67         struct nlattr **        attrbuf;        /* private */
  68         const struct genl_ops * ops;
  69         const struct genl_multicast_group *mcgrps;
  70         unsigned int            n_ops;
  71         unsigned int            n_mcgrps;
  72         unsigned int            mcgrp_offset;   /* private */
  73         struct module           *module;
  74 };
  75
  76 struct nlattr **genl_family_attrbuf(const struct genl_family *family);
  77
  78 /**
  79  * struct genl_info - receiving information
  80  * @snd_seq: sending sequence number
  81  * @snd_portid: netlink portid of sender
  82  * @nlhdr: netlink message header
  83  * @genlhdr: generic netlink message header
  84  * @userhdr: user specific header
  85  * @attrs: netlink attributes
  86  * @_net: network namespace
  87  * @user_ptr: user pointers
  88  * @extack: extended ACK report struct
  89  */
  90 struct genl_info {
  91         u32                     snd_seq;
  92         u32                     snd_portid;
  93         struct nlmsghdr *       nlhdr;
  94         struct genlmsghdr *     genlhdr;
  95         void *                  userhdr;
  96         struct nlattr **        attrs;
  97         possible_net_t          _net;
  98         void *                  user_ptr[2];
  99         struct netlink_ext_ack *extack;
 100 };
 101
 102 static inline struct net *genl_info_net(struct genl_info *info)
 103 {
 104         return read_pnet(&info->_net);
 105 }
 106
 107 static inline void genl_info_net_set(struct genl_info *info, struct net *net)
 108 {
 109         write_pnet(&info->_net, net);
 110 }
 111
 112 #define GENL_SET_ERR_MSG(info, msg) NL_SET_ERR_MSG((info)->extack, msg)
 113
 114 static inline int genl_err_attr(struct genl_info *info, int err,
 115                                 struct nlattr *attr)
 116 {
 117         info->extack->bad_attr = attr;
 118
 119         return err;
 120 }
 121
 122 /**
 123  * struct genl_ops - generic netlink operations
 124  * @cmd: command identifier
 125  * @internal_flags: flags used by the family
 126  * @flags: flags
 127  * @policy: attribute validation policy
 128  * @doit: standard command callback
 129  * @start: start callback for dumps
 130  * @dumpit: callback for dumpers
 131  * @done: completion callback for dumps
 132  */
 133 struct genl_ops {
 134         const struct nla_policy *policy;
 135         int                    (*doit)(struct sk_buff *skb,
 136                                        struct genl_info *info);
 137         int                    (*start)(struct netlink_callback *cb);
 138         int                    (*dumpit)(struct sk_buff *skb,
 139                                          struct netlink_callback *cb);
 140         int                    (*done)(struct netlink_callback *cb);
 141         u8                      cmd;
 142         u8                      internal_flags;
 143         u8                      flags;
 144 };
 145
 146 int genl_register_family(struct genl_family *family);
 147 int genl_unregister_family(const struct genl_family *family);
 148 void genl_notify(const struct genl_family *family, struct sk_buff *skb,
 149                  struct genl_info *info, u32 group, gfp_t flags);
 150
 151 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 152                   const struct genl_family *family, int flags, u8 cmd);
 153
 154 /**
 155  * genlmsg_nlhdr - Obtain netlink header from user specified header
 156  * @user_hdr: user header as returned from genlmsg_put()
 157  * @family: generic netlink family
 158  *
 159  * Returns pointer to netlink header.
 160  */
 161 static inline struct nlmsghdr *
 162 genlmsg_nlhdr(void *user_hdr, const struct genl_family *family)
 163 {
 164         return (struct nlmsghdr *)((char *)user_hdr -
 165                                    family->hdrsize -
 166                                    GENL_HDRLEN -
 167                                    NLMSG_HDRLEN);
 168 }
 169
 170 /**
 171  * genlmsg_parse - parse attributes of a genetlink message
 172  * @nlh: netlink message header
 173  * @family: genetlink message family
 174  * @tb: destination array with maxtype+1 elements
 175  * @maxtype: maximum attribute type to be expected
 176  * @policy: validation policy
 177  * @extack: extended ACK report struct
 178  */
 179 static inline int genlmsg_parse(const struct nlmsghdr *nlh,
 180                                 const struct genl_family *family,
 181                                 struct nlattr *tb[], int maxtype,
 182                                 const struct nla_policy *policy,
 183                                 struct netlink_ext_ack *extack)
 184 {
 185         return nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype,
 186                            policy, extack);
 187 }
 188
 189 /**
 190  * genl_dump_check_consistent - check if sequence is consistent and advertise if not
 191  * @cb: netlink callback structure that stores the sequence number
 192  * @user_hdr: user header as returned from genlmsg_put()
 193  * @family: generic netlink family
 194  *
 195  * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it
 196  * simpler to use with generic netlink.
 197  */
 198 static inline void genl_dump_check_consistent(struct netlink_callback *cb,
 199                                               void *user_hdr,
 200                                               const struct genl_family *family)
 201 {
 202         nl_dump_check_consistent(cb, genlmsg_nlhdr(user_hdr, family));
 203 }
 204
 205 /**
 206  * genlmsg_put_reply - Add generic netlink header to a reply message
 207  * @skb: socket buffer holding the message
 208  * @info: receiver info
 209  * @family: generic netlink family
 210  * @flags: netlink message flags
 211  * @cmd: generic netlink command
 212  *
 213  * Returns pointer to user specific header
 214  */
 215 static inline void *genlmsg_put_reply(struct sk_buff *skb,
 216                                       struct genl_info *info,
 217                                       const struct genl_family *family,
 218                                       int flags, u8 cmd)
 219 {
 220         return genlmsg_put(skb, info->snd_portid, info->snd_seq, family,
 221                            flags, cmd);
 222 }
 223
 224 /**
 225  * genlmsg_end - Finalize a generic netlink message
 226  * @skb: socket buffer the message is stored in
 227  * @hdr: user specific header
 228  */
 229 static inline void genlmsg_end(struct sk_buff *skb, void *hdr)
 230 {
 231         nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
 232 }
 233
 234 /**
 235  * genlmsg_cancel - Cancel construction of a generic netlink message
 236  * @skb: socket buffer the message is stored in
 237  * @hdr: generic netlink message header
 238  */
 239 static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr)
 240 {
 241         if (hdr)
 242                 nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
 243 }
 244
 245 /**
 246  * genlmsg_multicast_netns - multicast a netlink message to a specific netns
 247  * @family: the generic netlink family
 248  * @net: the net namespace
 249  * @skb: netlink message as socket buffer
 250  * @portid: own netlink portid to avoid sending to yourself
 251  * @group: offset of multicast group in groups array
 252  * @flags: allocation flags
 253  */
 254 static inline int genlmsg_multicast_netns(const struct genl_family *family,
 255                                           struct net *net, struct sk_buff *skb,
 256                                           u32 portid, unsigned int group, gfp_t flags)
 257 {
 258         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 259                 return -EINVAL;
 260         group = family->mcgrp_offset + group;
 261         return nlmsg_multicast(net->genl_sock, skb, portid, group, flags);
 262 }
 263
 264 /**
 265  * genlmsg_multicast - multicast a netlink message to the default netns
 266  * @family: the generic netlink family
 267  * @skb: netlink message as socket buffer
 268  * @portid: own netlink portid to avoid sending to yourself
 269  * @group: offset of multicast group in groups array
 270  * @flags: allocation flags
 271  */
 272 static inline int genlmsg_multicast(const struct genl_family *family,
 273                                     struct sk_buff *skb, u32 portid,
 274                                     unsigned int group, gfp_t flags)
 275 {
 276         return genlmsg_multicast_netns(family, &init_net, skb,
 277                                        portid, group, flags);
 278 }
 279
 280 /**
 281  * genlmsg_multicast_allns - multicast a netlink message to all net namespaces
 282  * @family: the generic netlink family
 283  * @skb: netlink message as socket buffer
 284  * @portid: own netlink portid to avoid sending to yourself
 285  * @group: offset of multicast group in groups array
 286  * @flags: allocation flags
 287  *
 288  * This function must hold the RTNL or rcu_read_lock().
 289  */
 290 int genlmsg_multicast_allns(const struct genl_family *family,
 291                             struct sk_buff *skb, u32 portid,
 292                             unsigned int group, gfp_t flags);
 293
 294 /**
 295  * genlmsg_unicast - unicast a netlink message
 296  * @skb: netlink message as socket buffer
 297  * @portid: netlink portid of the destination socket
 298  */
 299 static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid)
 300 {
 301         return nlmsg_unicast(net->genl_sock, skb, portid);
 302 }
 303
 304 /**
 305  * genlmsg_reply - reply to a request
 306  * @skb: netlink message to be sent back
 307  * @info: receiver information
 308  */
 309 static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info)
 310 {
 311         return genlmsg_unicast(genl_info_net(info), skb, info->snd_portid);
 312 }
 313
 314 /**
 315  * gennlmsg_data - head of message payload
 316  * @gnlh: genetlink message header
 317  */
 318 static inline void *genlmsg_data(const struct genlmsghdr *gnlh)
 319 {
 320         return ((unsigned char *) gnlh + GENL_HDRLEN);
 321 }
 322
 323 /**
 324  * genlmsg_len - length of message payload
 325  * @gnlh: genetlink message header
 326  */
 327 static inline int genlmsg_len(const struct genlmsghdr *gnlh)
 328 {
 329         struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh -
 330                                                         NLMSG_HDRLEN);
 331         return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
 332 }
 333
 334 /**
 335  * genlmsg_msg_size - length of genetlink message not including padding
 336  * @payload: length of message payload
 337  */
 338 static inline int genlmsg_msg_size(int payload)
 339 {
 340         return GENL_HDRLEN + payload;
 341 }
 342
 343 /**
 344  * genlmsg_total_size - length of genetlink message including padding
 345  * @payload: length of message payload
 346  */
 347 static inline int genlmsg_total_size(int payload)
 348 {
 349         return NLMSG_ALIGN(genlmsg_msg_size(payload));
 350 }
 351
 352 /**
 353  * genlmsg_new - Allocate a new generic netlink message
 354  * @payload: size of the message payload
 355  * @flags: the type of memory to allocate.
 356  */
 357 static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
 358 {
 359         return nlmsg_new(genlmsg_total_size(payload), flags);
 360 }
 361
 362 /**
 363  * genl_set_err - report error to genetlink broadcast listeners
 364  * @family: the generic netlink family
 365  * @net: the network namespace to report the error to
 366  * @portid: the PORTID of a process that we want to skip (if any)
 367  * @group: the broadcast group that will notice the error
 368  *      (this is the offset of the multicast group in the groups array)
 369  * @code: error code, must be negative (as usual in kernelspace)
 370  *
 371  * This function returns the number of broadcast listeners that have set the
 372  * NETLINK_RECV_NO_ENOBUFS socket option.
 373  */
 374 static inline int genl_set_err(const struct genl_family *family,
 375                                struct net *net, u32 portid,
 376                                u32 group, int code)
 377 {
 378         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 379                 return -EINVAL;
 380         group = family->mcgrp_offset + group;
 381         return netlink_set_err(net->genl_sock, portid, group, code);
 382 }
 383
 384 static inline int genl_has_listeners(const struct genl_family *family,
 385                                      struct net *net, unsigned int group)
 386 {
 387         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 388                 return -EINVAL;
 389         group = family->mcgrp_offset + group;
 390         return netlink_has_listeners(net->genl_sock, group);
 391 }
 392 #endif  /* __NET_GENERIC_NETLINK_H */