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 * @mcast_bind: a socket bound to the given multicast group (which 38 * is given as the offset into the groups array) 39 * @mcast_unbind: a socket was unbound from the given multicast group. 40 * Note that unbind() will not be called symmetrically if the 41 * generic netlink family is removed while there are still open 42 * sockets. 43 * @attrbuf: buffer to store parsed attributes (private) 44 * @mcgrps: multicast groups used by this family 45 * @n_mcgrps: number of multicast groups 46 * @mcgrp_offset: starting number of multicast group IDs in this family 47 * (private) 48 * @ops: the operations supported by this family 49 * @n_ops: number of operations supported by this family 50 */ 51 struct genl_family { 52 int id; /* private */ 53 unsigned int hdrsize; 54 char name[GENL_NAMSIZ]; 55 unsigned int version; 56 unsigned int maxattr; 57 bool netnsok; 58 bool parallel_ops; 59 int (*pre_doit)(const struct genl_ops *ops, 60 struct sk_buff *skb, 61 struct genl_info *info); 62 void (*post_doit)(const struct genl_ops *ops, 63 struct sk_buff *skb, 64 struct genl_info *info); 65 int (*mcast_bind)(struct net *net, int group); 66 void (*mcast_unbind)(struct net *net, int group); 67 struct nlattr ** attrbuf; /* private */ 68 const struct genl_ops * ops; 69 const struct genl_multicast_group *mcgrps; 70 unsigned int n_ops; 71 unsigned int n_mcgrps; 72 unsigned int mcgrp_offset; /* private */ 73 struct module *module; 74 }; 75 76 struct nlattr **genl_family_attrbuf(const struct genl_family *family); 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 struct nlattr *attr) 116 { 117 info->extack->bad_attr = attr; 118 119 return err; 120 } 121 122 /** 123 * struct genl_ops - generic netlink operations 124 * @cmd: command identifier 125 * @internal_flags: flags used by the family 126 * @flags: flags 127 * @policy: attribute validation policy 128 * @doit: standard command callback 129 * @start: start callback for dumps 130 * @dumpit: callback for dumpers 131 * @done: completion callback for dumps 132 */ 133 struct genl_ops { 134 const struct nla_policy *policy; 135 int (*doit)(struct sk_buff *skb, 136 struct genl_info *info); 137 int (*start)(struct netlink_callback *cb); 138 int (*dumpit)(struct sk_buff *skb, 139 struct netlink_callback *cb); 140 int (*done)(struct netlink_callback *cb); 141 u8 cmd; 142 u8 internal_flags; 143 u8 flags; 144 }; 145 146 int genl_register_family(struct genl_family *family); 147 int genl_unregister_family(const struct genl_family *family); 148 void genl_notify(const struct genl_family *family, struct sk_buff *skb, 149 struct genl_info *info, u32 group, gfp_t flags); 150 151 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, 152 const struct genl_family *family, int flags, u8 cmd); 153 154 /** 155 * genlmsg_nlhdr - Obtain netlink header from user specified header 156 * @user_hdr: user header as returned from genlmsg_put() 157 * @family: generic netlink family 158 * 159 * Returns pointer to netlink header. 160 */ 161 static inline struct nlmsghdr * 162 genlmsg_nlhdr(void *user_hdr, const struct genl_family *family) 163 { 164 return (struct nlmsghdr *)((char *)user_hdr - 165 family->hdrsize - 166 GENL_HDRLEN - 167 NLMSG_HDRLEN); 168 } 169 170 /** 171 * genlmsg_parse - parse attributes of a genetlink message 172 * @nlh: netlink message header 173 * @family: genetlink message family 174 * @tb: destination array with maxtype+1 elements 175 * @maxtype: maximum attribute type to be expected 176 * @policy: validation policy 177 * @extack: extended ACK report struct 178 */ 179 static inline int genlmsg_parse(const struct nlmsghdr *nlh, 180 const struct genl_family *family, 181 struct nlattr *tb[], int maxtype, 182 const struct nla_policy *policy, 183 struct netlink_ext_ack *extack) 184 { 185 return nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype, 186 policy, extack); 187 } 188 189 /** 190 * genl_dump_check_consistent - check if sequence is consistent and advertise if not 191 * @cb: netlink callback structure that stores the sequence number 192 * @user_hdr: user header as returned from genlmsg_put() 193 * @family: generic netlink family 194 * 195 * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it 196 * simpler to use with generic netlink. 197 */ 198 static inline void genl_dump_check_consistent(struct netlink_callback *cb, 199 void *user_hdr, 200 const struct genl_family *family) 201 { 202 nl_dump_check_consistent(cb, genlmsg_nlhdr(user_hdr, family)); 203 } 204 205 /** 206 * genlmsg_put_reply - Add generic netlink header to a reply message 207 * @skb: socket buffer holding the message 208 * @info: receiver info 209 * @family: generic netlink family 210 * @flags: netlink message flags 211 * @cmd: generic netlink command 212 * 213 * Returns pointer to user specific header 214 */ 215 static inline void *genlmsg_put_reply(struct sk_buff *skb, 216 struct genl_info *info, 217 const struct genl_family *family, 218 int flags, u8 cmd) 219 { 220 return genlmsg_put(skb, info->snd_portid, info->snd_seq, family, 221 flags, cmd); 222 } 223 224 /** 225 * genlmsg_end - Finalize a generic netlink message 226 * @skb: socket buffer the message is stored in 227 * @hdr: user specific header 228 */ 229 static inline void genlmsg_end(struct sk_buff *skb, void *hdr) 230 { 231 nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN); 232 } 233 234 /** 235 * genlmsg_cancel - Cancel construction of a generic netlink message 236 * @skb: socket buffer the message is stored in 237 * @hdr: generic netlink message header 238 */ 239 static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr) 240 { 241 if (hdr) 242 nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN); 243 } 244 245 /** 246 * genlmsg_multicast_netns - multicast a netlink message to a specific netns 247 * @family: the generic netlink family 248 * @net: the net namespace 249 * @skb: netlink message as socket buffer 250 * @portid: own netlink portid to avoid sending to yourself 251 * @group: offset of multicast group in groups array 252 * @flags: allocation flags 253 */ 254 static inline int genlmsg_multicast_netns(const struct genl_family *family, 255 struct net *net, struct sk_buff *skb, 256 u32 portid, unsigned int group, gfp_t flags) 257 { 258 if (WARN_ON_ONCE(group >= family->n_mcgrps)) 259 return -EINVAL; 260 group = family->mcgrp_offset + group; 261 return nlmsg_multicast(net->genl_sock, skb, portid, group, flags); 262 } 263 264 /** 265 * genlmsg_multicast - multicast a netlink message to the default netns 266 * @family: the generic netlink family 267 * @skb: netlink message as socket buffer 268 * @portid: own netlink portid to avoid sending to yourself 269 * @group: offset of multicast group in groups array 270 * @flags: allocation flags 271 */ 272 static inline int genlmsg_multicast(const struct genl_family *family, 273 struct sk_buff *skb, u32 portid, 274 unsigned int group, gfp_t flags) 275 { 276 return genlmsg_multicast_netns(family, &init_net, skb, 277 portid, group, flags); 278 } 279 280 /** 281 * genlmsg_multicast_allns - multicast a netlink message to all net namespaces 282 * @family: the generic netlink family 283 * @skb: netlink message as socket buffer 284 * @portid: own netlink portid to avoid sending to yourself 285 * @group: offset of multicast group in groups array 286 * @flags: allocation flags 287 * 288 * This function must hold the RTNL or rcu_read_lock(). 289 */ 290 int genlmsg_multicast_allns(const struct genl_family *family, 291 struct sk_buff *skb, u32 portid, 292 unsigned int group, gfp_t flags); 293 294 /** 295 * genlmsg_unicast - unicast a netlink message 296 * @skb: netlink message as socket buffer 297 * @portid: netlink portid of the destination socket 298 */ 299 static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid) 300 { 301 return nlmsg_unicast(net->genl_sock, skb, portid); 302 } 303 304 /** 305 * genlmsg_reply - reply to a request 306 * @skb: netlink message to be sent back 307 * @info: receiver information 308 */ 309 static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info) 310 { 311 return genlmsg_unicast(genl_info_net(info), skb, info->snd_portid); 312 } 313 314 /** 315 * gennlmsg_data - head of message payload 316 * @gnlh: genetlink message header 317 */ 318 static inline void *genlmsg_data(const struct genlmsghdr *gnlh) 319 { 320 return ((unsigned char *) gnlh + GENL_HDRLEN); 321 } 322 323 /** 324 * genlmsg_len - length of message payload 325 * @gnlh: genetlink message header 326 */ 327 static inline int genlmsg_len(const struct genlmsghdr *gnlh) 328 { 329 struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh - 330 NLMSG_HDRLEN); 331 return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN); 332 } 333 334 /** 335 * genlmsg_msg_size - length of genetlink message not including padding 336 * @payload: length of message payload 337 */ 338 static inline int genlmsg_msg_size(int payload) 339 { 340 return GENL_HDRLEN + payload; 341 } 342 343 /** 344 * genlmsg_total_size - length of genetlink message including padding 345 * @payload: length of message payload 346 */ 347 static inline int genlmsg_total_size(int payload) 348 { 349 return NLMSG_ALIGN(genlmsg_msg_size(payload)); 350 } 351 352 /** 353 * genlmsg_new - Allocate a new generic netlink message 354 * @payload: size of the message payload 355 * @flags: the type of memory to allocate. 356 */ 357 static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags) 358 { 359 return nlmsg_new(genlmsg_total_size(payload), flags); 360 } 361 362 /** 363 * genl_set_err - report error to genetlink broadcast listeners 364 * @family: the generic netlink family 365 * @net: the network namespace to report the error to 366 * @portid: the PORTID of a process that we want to skip (if any) 367 * @group: the broadcast group that will notice the error 368 * (this is the offset of the multicast group in the groups array) 369 * @code: error code, must be negative (as usual in kernelspace) 370 * 371 * This function returns the number of broadcast listeners that have set the 372 * NETLINK_RECV_NO_ENOBUFS socket option. 373 */ 374 static inline int genl_set_err(const struct genl_family *family, 375 struct net *net, u32 portid, 376 u32 group, int code) 377 { 378 if (WARN_ON_ONCE(group >= family->n_mcgrps)) 379 return -EINVAL; 380 group = family->mcgrp_offset + group; 381 return netlink_set_err(net->genl_sock, portid, group, code); 382 } 383 384 static inline int genl_has_listeners(const struct genl_family *family, 385 struct net *net, unsigned int group) 386 { 387 if (WARN_ON_ONCE(group >= family->n_mcgrps)) 388 return -EINVAL; 389 group = family->mcgrp_offset + group; 390 return netlink_has_listeners(net->genl_sock, group); 391 } 392 #endif /* __NET_GENERIC_NETLINK_H */ 393