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