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