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