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  * @policy: netlink policy
  30  * @netnsok: set to true if the family can handle network
  31  *      namespaces and should be presented in all of them
  32  * @parallel_ops: operations can be called in parallel and aren't
  33  *      synchronized by the core genetlink code
  34  * @pre_doit: called before an operation's doit callback, it may
  35  *      do additional, common, filtering and return an error
  36  * @post_doit: called after an operation's doit callback, it may
  37  *      undo operations done by pre_doit, for example release locks
  38  * @mcgrps: multicast groups used by this family
  39  * @n_mcgrps: number of multicast groups
  40  * @mcgrp_offset: starting number of multicast group IDs in this family
  41  *      (private)
  42  * @ops: the operations supported by this family
  43  * @n_ops: number of operations supported by this family
  44  * @small_ops: the small-struct operations supported by this family
  45  * @n_small_ops: number of small-struct operations supported by this family
  46  */
  47 struct genl_family {
  48         int                     id;             /* private */
  49         unsigned int            hdrsize;
  50         char                    name[GENL_NAMSIZ];
  51         unsigned int            version;
  52         unsigned int            maxattr;
  53         unsigned int            mcgrp_offset;   /* private */
  54         u8                      netnsok:1;
  55         u8                      parallel_ops:1;
  56         u8                      n_ops;
  57         u8                      n_small_ops;
  58         u8                      n_mcgrps;
  59         const struct nla_policy *policy;
  60         int                     (*pre_doit)(const struct genl_ops *ops,
  61                                             struct sk_buff *skb,
  62                                             struct genl_info *info);
  63         void                    (*post_doit)(const struct genl_ops *ops,
  64                                              struct sk_buff *skb,
  65                                              struct genl_info *info);
  66         const struct genl_ops * ops;
  67         const struct genl_small_ops *small_ops;
  68         const struct genl_multicast_group *mcgrps;
  69         struct module           *module;
  70 };
  71
  72 /**
  73  * struct genl_info - receiving information
  74  * @snd_seq: sending sequence number
  75  * @snd_portid: netlink portid of sender
  76  * @nlhdr: netlink message header
  77  * @genlhdr: generic netlink message header
  78  * @userhdr: user specific header
  79  * @attrs: netlink attributes
  80  * @_net: network namespace
  81  * @user_ptr: user pointers
  82  * @extack: extended ACK report struct
  83  */
  84 struct genl_info {
  85         u32                     snd_seq;
  86         u32                     snd_portid;
  87         struct nlmsghdr *       nlhdr;
  88         struct genlmsghdr *     genlhdr;
  89         void *                  userhdr;
  90         struct nlattr **        attrs;
  91         possible_net_t          _net;
  92         void *                  user_ptr[2];
  93         struct netlink_ext_ack *extack;
  94 };
  95
  96 static inline struct net *genl_info_net(struct genl_info *info)
  97 {
  98         return read_pnet(&info->_net);
  99 }
 100
 101 static inline void genl_info_net_set(struct genl_info *info, struct net *net)
 102 {
 103         write_pnet(&info->_net, net);
 104 }
 105
 106 #define GENL_SET_ERR_MSG(info, msg) NL_SET_ERR_MSG((info)->extack, msg)
 107
 108 enum genl_validate_flags {
 109         GENL_DONT_VALIDATE_STRICT               = BIT(0),
 110         GENL_DONT_VALIDATE_DUMP                 = BIT(1),
 111         GENL_DONT_VALIDATE_DUMP_STRICT          = BIT(2),
 112 };
 113
 114 /**
 115  * struct genl_small_ops - generic netlink operations (small version)
 116  * @cmd: command identifier
 117  * @internal_flags: flags used by the family
 118  * @flags: flags
 119  * @validate: validation flags from enum genl_validate_flags
 120  * @doit: standard command callback
 121  * @dumpit: callback for dumpers
 122  *
 123  * This is a cut-down version of struct genl_ops for users who don't need
 124  * most of the ancillary infra and want to save space.
 125  */
 126 struct genl_small_ops {
 127         int     (*doit)(struct sk_buff *skb, struct genl_info *info);
 128         int     (*dumpit)(struct sk_buff *skb, struct netlink_callback *cb);
 129         u8      cmd;
 130         u8      internal_flags;
 131         u8      flags;
 132         u8      validate;
 133 };
 134
 135 /**
 136  * struct genl_ops - generic netlink operations
 137  * @cmd: command identifier
 138  * @internal_flags: flags used by the family
 139  * @flags: flags
 140  * @maxattr: maximum number of attributes supported
 141  * @policy: netlink policy (takes precedence over family policy)
 142  * @validate: validation flags from enum genl_validate_flags
 143  * @doit: standard command callback
 144  * @start: start callback for dumps
 145  * @dumpit: callback for dumpers
 146  * @done: completion callback for dumps
 147  */
 148 struct genl_ops {
 149         int                    (*doit)(struct sk_buff *skb,
 150                                        struct genl_info *info);
 151         int                    (*start)(struct netlink_callback *cb);
 152         int                    (*dumpit)(struct sk_buff *skb,
 153                                          struct netlink_callback *cb);
 154         int                    (*done)(struct netlink_callback *cb);
 155         const struct nla_policy *policy;
 156         unsigned int            maxattr;
 157         u8                      cmd;
 158         u8                      internal_flags;
 159         u8                      flags;
 160         u8                      validate;
 161 };
 162
 163 /**
 164  * struct genl_info - info that is available during dumpit op call
 165  * @family: generic netlink family - for internal genl code usage
 166  * @ops: generic netlink ops - for internal genl code usage
 167  * @attrs: netlink attributes
 168  */
 169 struct genl_dumpit_info {
 170         const struct genl_family *family;
 171         struct genl_ops op;
 172         struct nlattr **attrs;
 173 };
 174
 175 static inline const struct genl_dumpit_info *
 176 genl_dumpit_info(struct netlink_callback *cb)
 177 {
 178         return cb->data;
 179 }
 180
 181 int genl_register_family(struct genl_family *family);
 182 int genl_unregister_family(const struct genl_family *family);
 183 void genl_notify(const struct genl_family *family, struct sk_buff *skb,
 184                  struct genl_info *info, u32 group, gfp_t flags);
 185
 186 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 187                   const struct genl_family *family, int flags, u8 cmd);
 188
 189 /**
 190  * genlmsg_nlhdr - Obtain netlink header from user specified header
 191  * @user_hdr: user header as returned from genlmsg_put()
 192  *
 193  * Returns pointer to netlink header.
 194  */
 195 static inline struct nlmsghdr *genlmsg_nlhdr(void *user_hdr)
 196 {
 197         return (struct nlmsghdr *)((char *)user_hdr -
 198                                    GENL_HDRLEN -
 199                                    NLMSG_HDRLEN);
 200 }
 201
 202 /**
 203  * genlmsg_parse_deprecated - parse attributes of a genetlink message
 204  * @nlh: netlink message header
 205  * @family: genetlink message family
 206  * @tb: destination array with maxtype+1 elements
 207  * @maxtype: maximum attribute type to be expected
 208  * @policy: validation policy
 209  * @extack: extended ACK report struct
 210  */
 211 static inline int genlmsg_parse_deprecated(const struct nlmsghdr *nlh,
 212                                            const struct genl_family *family,
 213                                            struct nlattr *tb[], int maxtype,
 214                                            const struct nla_policy *policy,
 215                                            struct netlink_ext_ack *extack)
 216 {
 217         return __nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype,
 218                              policy, NL_VALIDATE_LIBERAL, extack);
 219 }
 220
 221 /**
 222  * genlmsg_parse - parse attributes of a genetlink message
 223  * @nlh: netlink message header
 224  * @family: genetlink message family
 225  * @tb: destination array with maxtype+1 elements
 226  * @maxtype: maximum attribute type to be expected
 227  * @policy: validation policy
 228  * @extack: extended ACK report struct
 229  */
 230 static inline int genlmsg_parse(const struct nlmsghdr *nlh,
 231                                 const struct genl_family *family,
 232                                 struct nlattr *tb[], int maxtype,
 233                                 const struct nla_policy *policy,
 234                                 struct netlink_ext_ack *extack)
 235 {
 236         return __nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype,
 237                              policy, NL_VALIDATE_STRICT, extack);
 238 }
 239
 240 /**
 241  * genl_dump_check_consistent - check if sequence is consistent and advertise if not
 242  * @cb: netlink callback structure that stores the sequence number
 243  * @user_hdr: user header as returned from genlmsg_put()
 244  *
 245  * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it
 246  * simpler to use with generic netlink.
 247  */
 248 static inline void genl_dump_check_consistent(struct netlink_callback *cb,
 249                                               void *user_hdr)
 250 {
 251         nl_dump_check_consistent(cb, genlmsg_nlhdr(user_hdr));
 252 }
 253
 254 /**
 255  * genlmsg_put_reply - Add generic netlink header to a reply message
 256  * @skb: socket buffer holding the message
 257  * @info: receiver info
 258  * @family: generic netlink family
 259  * @flags: netlink message flags
 260  * @cmd: generic netlink command
 261  *
 262  * Returns pointer to user specific header
 263  */
 264 static inline void *genlmsg_put_reply(struct sk_buff *skb,
 265                                       struct genl_info *info,
 266                                       const struct genl_family *family,
 267                                       int flags, u8 cmd)
 268 {
 269         return genlmsg_put(skb, info->snd_portid, info->snd_seq, family,
 270                            flags, cmd);
 271 }
 272
 273 /**
 274  * genlmsg_end - Finalize a generic netlink message
 275  * @skb: socket buffer the message is stored in
 276  * @hdr: user specific header
 277  */
 278 static inline void genlmsg_end(struct sk_buff *skb, void *hdr)
 279 {
 280         nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
 281 }
 282
 283 /**
 284  * genlmsg_cancel - Cancel construction of a generic netlink message
 285  * @skb: socket buffer the message is stored in
 286  * @hdr: generic netlink message header
 287  */
 288 static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr)
 289 {
 290         if (hdr)
 291                 nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
 292 }
 293
 294 /**
 295  * genlmsg_multicast_netns - multicast a netlink message to a specific netns
 296  * @family: the generic netlink family
 297  * @net: the net namespace
 298  * @skb: netlink message as socket buffer
 299  * @portid: own netlink portid to avoid sending to yourself
 300  * @group: offset of multicast group in groups array
 301  * @flags: allocation flags
 302  */
 303 static inline int genlmsg_multicast_netns(const struct genl_family *family,
 304                                           struct net *net, struct sk_buff *skb,
 305                                           u32 portid, unsigned int group, gfp_t flags)
 306 {
 307         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 308                 return -EINVAL;
 309         group = family->mcgrp_offset + group;
 310         return nlmsg_multicast(net->genl_sock, skb, portid, group, flags);
 311 }
 312
 313 /**
 314  * genlmsg_multicast - multicast a netlink message to the default netns
 315  * @family: the generic netlink family
 316  * @skb: netlink message as socket buffer
 317  * @portid: own netlink portid to avoid sending to yourself
 318  * @group: offset of multicast group in groups array
 319  * @flags: allocation flags
 320  */
 321 static inline int genlmsg_multicast(const struct genl_family *family,
 322                                     struct sk_buff *skb, u32 portid,
 323                                     unsigned int group, gfp_t flags)
 324 {
 325         return genlmsg_multicast_netns(family, &init_net, skb,
 326                                        portid, group, flags);
 327 }
 328
 329 /**
 330  * genlmsg_multicast_allns - multicast a netlink message to all net namespaces
 331  * @family: the generic netlink family
 332  * @skb: netlink message as socket buffer
 333  * @portid: own netlink portid to avoid sending to yourself
 334  * @group: offset of multicast group in groups array
 335  * @flags: allocation flags
 336  *
 337  * This function must hold the RTNL or rcu_read_lock().
 338  */
 339 int genlmsg_multicast_allns(const struct genl_family *family,
 340                             struct sk_buff *skb, u32 portid,
 341                             unsigned int group, gfp_t flags);
 342
 343 /**
 344  * genlmsg_unicast - unicast a netlink message
 345  * @skb: netlink message as socket buffer
 346  * @portid: netlink portid of the destination socket
 347  */
 348 static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid)
 349 {
 350         return nlmsg_unicast(net->genl_sock, skb, portid);
 351 }
 352
 353 /**
 354  * genlmsg_reply - reply to a request
 355  * @skb: netlink message to be sent back
 356  * @info: receiver information
 357  */
 358 static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info)
 359 {
 360         return genlmsg_unicast(genl_info_net(info), skb, info->snd_portid);
 361 }
 362
 363 /**
 364  * gennlmsg_data - head of message payload
 365  * @gnlh: genetlink message header
 366  */
 367 static inline void *genlmsg_data(const struct genlmsghdr *gnlh)
 368 {
 369         return ((unsigned char *) gnlh + GENL_HDRLEN);
 370 }
 371
 372 /**
 373  * genlmsg_len - length of message payload
 374  * @gnlh: genetlink message header
 375  */
 376 static inline int genlmsg_len(const struct genlmsghdr *gnlh)
 377 {
 378         struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh -
 379                                                         NLMSG_HDRLEN);
 380         return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
 381 }
 382
 383 /**
 384  * genlmsg_msg_size - length of genetlink message not including padding
 385  * @payload: length of message payload
 386  */
 387 static inline int genlmsg_msg_size(int payload)
 388 {
 389         return GENL_HDRLEN + payload;
 390 }
 391
 392 /**
 393  * genlmsg_total_size - length of genetlink message including padding
 394  * @payload: length of message payload
 395  */
 396 static inline int genlmsg_total_size(int payload)
 397 {
 398         return NLMSG_ALIGN(genlmsg_msg_size(payload));
 399 }
 400
 401 /**
 402  * genlmsg_new - Allocate a new generic netlink message
 403  * @payload: size of the message payload
 404  * @flags: the type of memory to allocate.
 405  */
 406 static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags)
 407 {
 408         return nlmsg_new(genlmsg_total_size(payload), flags);
 409 }
 410
 411 /**
 412  * genl_set_err - report error to genetlink broadcast listeners
 413  * @family: the generic netlink family
 414  * @net: the network namespace to report the error to
 415  * @portid: the PORTID of a process that we want to skip (if any)
 416  * @group: the broadcast group that will notice the error
 417  *      (this is the offset of the multicast group in the groups array)
 418  * @code: error code, must be negative (as usual in kernelspace)
 419  *
 420  * This function returns the number of broadcast listeners that have set the
 421  * NETLINK_RECV_NO_ENOBUFS socket option.
 422  */
 423 static inline int genl_set_err(const struct genl_family *family,
 424                                struct net *net, u32 portid,
 425                                u32 group, int code)
 426 {
 427         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 428                 return -EINVAL;
 429         group = family->mcgrp_offset + group;
 430         return netlink_set_err(net->genl_sock, portid, group, code);
 431 }
 432
 433 static inline int genl_has_listeners(const struct genl_family *family,
 434                                      struct net *net, unsigned int group)
 435 {
 436         if (WARN_ON_ONCE(group >= family->n_mcgrps))
 437                 return -EINVAL;
 438         group = family->mcgrp_offset + group;
 439         return netlink_has_listeners(net->genl_sock, group);
 440 }
 441 #endif  /* __NET_GENERIC_NETLINK_H */