1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __LINUX_NETLINK_H 3 #define __LINUX_NETLINK_H 4 5 6 #include <linux/capability.h> 7 #include <linux/skbuff.h> 8 #include <linux/export.h> 9 #include <net/scm.h> 10 #include <uapi/linux/netlink.h> 11 12 struct net; 13 14 void do_trace_netlink_extack(const char *msg); 15 nlmsg_hdr(const struct sk_buff * skb)16 static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb) 17 { 18 return (struct nlmsghdr *)skb->data; 19 } 20 21 enum netlink_skb_flags { 22 NETLINK_SKB_DST = 0x8, /* Dst set in sendto or sendmsg */ 23 }; 24 25 struct netlink_skb_parms { 26 struct scm_creds creds; /* Skb credentials */ 27 __u32 portid; 28 __u32 dst_group; 29 __u32 flags; 30 struct sock *sk; 31 bool nsid_is_set; 32 int nsid; 33 }; 34 35 #define NETLINK_CB(skb) (*(struct netlink_skb_parms*)&((skb)->cb)) 36 #define NETLINK_CREDS(skb) (&NETLINK_CB((skb)).creds) 37 38 39 void netlink_table_grab(void); 40 void netlink_table_ungrab(void); 41 42 #define NL_CFG_F_NONROOT_RECV (1 << 0) 43 #define NL_CFG_F_NONROOT_SEND (1 << 1) 44 45 /* optional Netlink kernel configuration parameters */ 46 struct netlink_kernel_cfg { 47 unsigned int groups; 48 unsigned int flags; 49 void (*input)(struct sk_buff *skb); 50 int (*bind)(struct net *net, int group); 51 void (*unbind)(struct net *net, int group); 52 void (*release) (struct sock *sk, unsigned long *groups); 53 }; 54 55 struct sock *__netlink_kernel_create(struct net *net, int unit, 56 struct module *module, 57 struct netlink_kernel_cfg *cfg); 58 static inline struct sock * netlink_kernel_create(struct net * net,int unit,struct netlink_kernel_cfg * cfg)59 netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg) 60 { 61 return __netlink_kernel_create(net, unit, THIS_MODULE, cfg); 62 } 63 64 /* this can be increased when necessary - don't expose to userland */ 65 #define NETLINK_MAX_COOKIE_LEN 20 66 #define NETLINK_MAX_FMTMSG_LEN 80 67 68 /** 69 * struct netlink_ext_ack - netlink extended ACK report struct 70 * @_msg: message string to report - don't access directly, use 71 * %NL_SET_ERR_MSG 72 * @bad_attr: attribute with error 73 * @policy: policy for a bad attribute 74 * @miss_type: attribute type which was missing 75 * @miss_nest: nest missing an attribute (%NULL if missing top level attr) 76 * @cookie: cookie data to return to userspace (for success) 77 * @cookie_len: actual cookie data length 78 * @_msg_buf: output buffer for formatted message strings - don't access 79 * directly, use %NL_SET_ERR_MSG_FMT 80 */ 81 struct netlink_ext_ack { 82 const char *_msg; 83 const struct nlattr *bad_attr; 84 const struct nla_policy *policy; 85 const struct nlattr *miss_nest; 86 u16 miss_type; 87 u8 cookie[NETLINK_MAX_COOKIE_LEN]; 88 u8 cookie_len; 89 char _msg_buf[NETLINK_MAX_FMTMSG_LEN]; 90 }; 91 92 /* Always use this macro, this allows later putting the 93 * message into a separate section or such for things 94 * like translation or listing all possible messages. 95 * If string formatting is needed use NL_SET_ERR_MSG_FMT. 96 */ 97 #define NL_SET_ERR_MSG(extack, msg) do { \ 98 static const char __msg[] = msg; \ 99 struct netlink_ext_ack *__extack = (extack); \ 100 \ 101 do_trace_netlink_extack(__msg); \ 102 \ 103 if (__extack) \ 104 __extack->_msg = __msg; \ 105 } while (0) 106 107 /* We splice fmt with %s at each end even in the snprintf so that both calls 108 * can use the same string constant, avoiding its duplication in .ro 109 */ 110 #define NL_SET_ERR_MSG_FMT(extack, fmt, args...) do { \ 111 struct netlink_ext_ack *__extack = (extack); \ 112 \ 113 if (!__extack) \ 114 break; \ 115 if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \ 116 "%s" fmt "%s", "", ##args, "") >= \ 117 NETLINK_MAX_FMTMSG_LEN) \ 118 net_warn_ratelimited("%s" fmt "%s", "truncated extack: ", \ 119 ##args, "\n"); \ 120 \ 121 do_trace_netlink_extack(__extack->_msg_buf); \ 122 \ 123 __extack->_msg = __extack->_msg_buf; \ 124 } while (0) 125 126 #define NL_SET_ERR_MSG_MOD(extack, msg) \ 127 NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg) 128 129 #define NL_SET_ERR_MSG_FMT_MOD(extack, fmt, args...) \ 130 NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args) 131 132 #define NL_SET_ERR_MSG_WEAK(extack, msg) do { \ 133 if ((extack) && !(extack)->_msg) \ 134 NL_SET_ERR_MSG((extack), msg); \ 135 } while (0) 136 137 #define NL_SET_ERR_MSG_WEAK_MOD(extack, msg) do { \ 138 if ((extack) && !(extack)->_msg) \ 139 NL_SET_ERR_MSG_MOD((extack), msg); \ 140 } while (0) 141 142 #define NL_SET_BAD_ATTR_POLICY(extack, attr, pol) do { \ 143 if ((extack)) { \ 144 (extack)->bad_attr = (attr); \ 145 (extack)->policy = (pol); \ 146 } \ 147 } while (0) 148 149 #define NL_SET_BAD_ATTR(extack, attr) NL_SET_BAD_ATTR_POLICY(extack, attr, NULL) 150 151 #define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) do { \ 152 static const char __msg[] = msg; \ 153 struct netlink_ext_ack *__extack = (extack); \ 154 \ 155 do_trace_netlink_extack(__msg); \ 156 \ 157 if (__extack) { \ 158 __extack->_msg = __msg; \ 159 __extack->bad_attr = (attr); \ 160 __extack->policy = (pol); \ 161 } \ 162 } while (0) 163 164 #define NL_SET_ERR_MSG_ATTR_POL_FMT(extack, attr, pol, fmt, args...) do { \ 165 struct netlink_ext_ack *__extack = (extack); \ 166 \ 167 if (!__extack) \ 168 break; \ 169 \ 170 if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \ 171 "%s" fmt "%s", "", ##args, "") >= \ 172 NETLINK_MAX_FMTMSG_LEN) \ 173 net_warn_ratelimited("%s" fmt "%s", "truncated extack: ", \ 174 ##args, "\n"); \ 175 \ 176 do_trace_netlink_extack(__extack->_msg_buf); \ 177 \ 178 __extack->_msg = __extack->_msg_buf; \ 179 __extack->bad_attr = (attr); \ 180 __extack->policy = (pol); \ 181 } while (0) 182 183 #define NL_SET_ERR_MSG_ATTR(extack, attr, msg) \ 184 NL_SET_ERR_MSG_ATTR_POL(extack, attr, NULL, msg) 185 186 #define NL_SET_ERR_MSG_ATTR_FMT(extack, attr, msg, args...) \ 187 NL_SET_ERR_MSG_ATTR_POL_FMT(extack, attr, NULL, msg, ##args) 188 189 #define NL_SET_ERR_ATTR_MISS(extack, nest, type) do { \ 190 struct netlink_ext_ack *__extack = (extack); \ 191 \ 192 if (__extack) { \ 193 __extack->miss_nest = (nest); \ 194 __extack->miss_type = (type); \ 195 } \ 196 } while (0) 197 198 #define NL_REQ_ATTR_CHECK(extack, nest, tb, type) ({ \ 199 struct nlattr **__tb = (tb); \ 200 u32 __attr = (type); \ 201 int __retval; \ 202 \ 203 __retval = !__tb[__attr]; \ 204 if (__retval) \ 205 NL_SET_ERR_ATTR_MISS((extack), (nest), __attr); \ 206 __retval; \ 207 }) 208 nl_set_extack_cookie_u64(struct netlink_ext_ack * extack,u64 cookie)209 static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack, 210 u64 cookie) 211 { 212 if (!extack) 213 return; 214 memcpy(extack->cookie, &cookie, sizeof(cookie)); 215 extack->cookie_len = sizeof(cookie); 216 } 217 218 void netlink_kernel_release(struct sock *sk); 219 int __netlink_change_ngroups(struct sock *sk, unsigned int groups); 220 int netlink_change_ngroups(struct sock *sk, unsigned int groups); 221 void __netlink_clear_multicast_users(struct sock *sk, unsigned int group); 222 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err, 223 const struct netlink_ext_ack *extack); 224 int netlink_has_listeners(struct sock *sk, unsigned int group); 225 bool netlink_strict_get_check(struct sk_buff *skb); 226 227 int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock); 228 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid, 229 __u32 group, gfp_t allocation); 230 231 typedef int (*netlink_filter_fn)(struct sock *dsk, struct sk_buff *skb, void *data); 232 233 int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb, 234 __u32 portid, __u32 group, gfp_t allocation, 235 netlink_filter_fn filter, 236 void *filter_data); 237 int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code); 238 int netlink_register_notifier(struct notifier_block *nb); 239 int netlink_unregister_notifier(struct notifier_block *nb); 240 241 /* finegrained unicast helpers: */ 242 struct sock *netlink_getsockbyfilp(struct file *filp); 243 int netlink_attachskb(struct sock *sk, struct sk_buff *skb, 244 long *timeo, struct sock *ssk); 245 void netlink_detachskb(struct sock *sk, struct sk_buff *skb); 246 int netlink_sendskb(struct sock *sk, struct sk_buff *skb); 247 248 static inline struct sk_buff * netlink_skb_clone(struct sk_buff * skb,gfp_t gfp_mask)249 netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask) 250 { 251 struct sk_buff *nskb; 252 253 nskb = skb_clone(skb, gfp_mask); 254 if (!nskb) 255 return NULL; 256 257 /* This is a large skb, set destructor callback to release head */ 258 if (is_vmalloc_addr(skb->head)) 259 nskb->destructor = skb->destructor; 260 261 return nskb; 262 } 263 264 /* 265 * skb should fit one page. This choice is good for headerless malloc. 266 * But we should limit to 8K so that userspace does not have to 267 * use enormous buffer sizes on recvmsg() calls just to avoid 268 * MSG_TRUNC when PAGE_SIZE is very large. 269 */ 270 #if PAGE_SIZE < 8192UL 271 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(PAGE_SIZE) 272 #else 273 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(8192UL) 274 #endif 275 276 #define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN) 277 278 279 struct netlink_callback { 280 struct sk_buff *skb; 281 const struct nlmsghdr *nlh; 282 int (*dump)(struct sk_buff * skb, 283 struct netlink_callback *cb); 284 int (*done)(struct netlink_callback *cb); 285 void *data; 286 /* the module that dump function belong to */ 287 struct module *module; 288 struct netlink_ext_ack *extack; 289 u16 family; 290 u16 answer_flags; 291 u32 min_dump_alloc; 292 unsigned int prev_seq, seq; 293 int flags; 294 bool strict_check; 295 union { 296 u8 ctx[48]; 297 298 /* args is deprecated. Cast a struct over ctx instead 299 * for proper type safety. 300 */ 301 long args[6]; 302 }; 303 }; 304 305 #define NL_ASSERT_DUMP_CTX_FITS(type_name) \ 306 BUILD_BUG_ON(sizeof(type_name) > \ 307 sizeof_field(struct netlink_callback, ctx)) 308 309 struct netlink_notify { 310 struct net *net; 311 u32 portid; 312 int protocol; 313 }; 314 315 struct nlmsghdr * 316 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags); 317 318 struct netlink_dump_control { 319 int (*start)(struct netlink_callback *); 320 int (*dump)(struct sk_buff *skb, struct netlink_callback *); 321 int (*done)(struct netlink_callback *); 322 struct netlink_ext_ack *extack; 323 void *data; 324 struct module *module; 325 u32 min_dump_alloc; 326 int flags; 327 }; 328 329 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 330 const struct nlmsghdr *nlh, 331 struct netlink_dump_control *control); netlink_dump_start(struct sock * ssk,struct sk_buff * skb,const struct nlmsghdr * nlh,struct netlink_dump_control * control)332 static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 333 const struct nlmsghdr *nlh, 334 struct netlink_dump_control *control) 335 { 336 if (!control->module) 337 control->module = THIS_MODULE; 338 339 return __netlink_dump_start(ssk, skb, nlh, control); 340 } 341 342 struct netlink_tap { 343 struct net_device *dev; 344 struct module *module; 345 struct list_head list; 346 }; 347 348 int netlink_add_tap(struct netlink_tap *nt); 349 int netlink_remove_tap(struct netlink_tap *nt); 350 351 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp, 352 struct user_namespace *ns, int cap); 353 bool netlink_ns_capable(const struct sk_buff *skb, 354 struct user_namespace *ns, int cap); 355 bool netlink_capable(const struct sk_buff *skb, int cap); 356 bool netlink_net_capable(const struct sk_buff *skb, int cap); 357 struct sk_buff *netlink_alloc_large_skb(unsigned int size, int broadcast); 358 359 #endif /* __LINUX_NETLINK_H */ 360