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