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 12struct net; 13 14void do_trace_netlink_extack(const char *msg); 15 16static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb) 17{ 18 return (struct nlmsghdr *)skb->data; 19} 20 21enum netlink_skb_flags { 22 NETLINK_SKB_DST = 0x8, /* Dst set in sendto or sendmsg */ 23}; 24 25struct 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 39void netlink_table_grab(void); 40void 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 */ 46struct netlink_kernel_cfg { 47 unsigned int groups; 48 unsigned int flags; 49 void (*input)(struct sk_buff *skb); 50 struct mutex *cb_mutex; 51 int (*bind)(struct net *net, int group); 52 void (*unbind)(struct net *net, int group); 53 void (*release) (struct sock *sk, unsigned long *groups); 54}; 55 56struct sock *__netlink_kernel_create(struct net *net, int unit, 57 struct module *module, 58 struct netlink_kernel_cfg *cfg); 59static inline struct sock * 60netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg) 61{ 62 return __netlink_kernel_create(net, unit, THIS_MODULE, cfg); 63} 64 65/* this can be increased when necessary - don't expose to userland */ 66#define NETLINK_MAX_COOKIE_LEN 20 67#define NETLINK_MAX_FMTMSG_LEN 80 68 69/** 70 * struct netlink_ext_ack - netlink extended ACK report struct 71 * @_msg: message string to report - don't access directly, use 72 * %NL_SET_ERR_MSG 73 * @bad_attr: attribute with error 74 * @policy: policy for a bad attribute 75 * @miss_type: attribute type which was missing 76 * @miss_nest: nest missing an attribute (%NULL if missing top level attr) 77 * @cookie: cookie data to return to userspace (for success) 78 * @cookie_len: actual cookie data length 79 * @_msg_buf: output buffer for formatted message strings - don't access 80 * directly, use %NL_SET_ERR_MSG_FMT 81 */ 82struct netlink_ext_ack { 83 const char *_msg; 84 const struct nlattr *bad_attr; 85 const struct nla_policy *policy; 86 const struct nlattr *miss_nest; 87 u16 miss_type; 88 u8 cookie[NETLINK_MAX_COOKIE_LEN]; 89 u8 cookie_len; 90 char _msg_buf[NETLINK_MAX_FMTMSG_LEN]; 91}; 92 93/* Always use this macro, this allows later putting the 94 * message into a separate section or such for things 95 * like translation or listing all possible messages. 96 * If string formatting is needed use NL_SET_ERR_MSG_FMT. 97 */ 98#define NL_SET_ERR_MSG(extack, msg) do { \ 99 static const char __msg[] = msg; \ 100 struct netlink_ext_ack *__extack = (extack); \ 101 \ 102 do_trace_netlink_extack(__msg); \ 103 \ 104 if (__extack) \ 105 __extack->_msg = __msg; \ 106} while (0) 107 108/* We splice fmt with %s at each end even in the snprintf so that both calls 109 * can use the same string constant, avoiding its duplication in .ro 110 */ 111#define NL_SET_ERR_MSG_FMT(extack, fmt, args...) do { \ 112 struct netlink_ext_ack *__extack = (extack); \ 113 \ 114 if (!__extack) \ 115 break; \ 116 if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \ 117 "%s" fmt "%s", "", ##args, "") >= \ 118 NETLINK_MAX_FMTMSG_LEN) \ 119 net_warn_ratelimited("%s" fmt "%s", "truncated extack: ", \ 120 ##args, "\n"); \ 121 \ 122 do_trace_netlink_extack(__extack->_msg_buf); \ 123 \ 124 __extack->_msg = __extack->_msg_buf; \ 125} while (0) 126 127#define NL_SET_ERR_MSG_MOD(extack, msg) \ 128 NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg) 129 130#define NL_SET_ERR_MSG_FMT_MOD(extack, fmt, args...) \ 131 NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args) 132 133#define NL_SET_ERR_MSG_WEAK(extack, msg) do { \ 134 if ((extack) && !(extack)->_msg) \ 135 NL_SET_ERR_MSG((extack), msg); \ 136} while (0) 137 138#define NL_SET_ERR_MSG_WEAK_MOD(extack, msg) do { \ 139 if ((extack) && !(extack)->_msg) \ 140 NL_SET_ERR_MSG_MOD((extack), msg); \ 141} while (0) 142 143#define NL_SET_BAD_ATTR_POLICY(extack, attr, pol) do { \ 144 if ((extack)) { \ 145 (extack)->bad_attr = (attr); \ 146 (extack)->policy = (pol); \ 147 } \ 148} while (0) 149 150#define NL_SET_BAD_ATTR(extack, attr) NL_SET_BAD_ATTR_POLICY(extack, attr, NULL) 151 152#define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) do { \ 153 static const char __msg[] = msg; \ 154 struct netlink_ext_ack *__extack = (extack); \ 155 \ 156 do_trace_netlink_extack(__msg); \ 157 \ 158 if (__extack) { \ 159 __extack->_msg = __msg; \ 160 __extack->bad_attr = (attr); \ 161 __extack->policy = (pol); \ 162 } \ 163} while (0) 164 165#define NL_SET_ERR_MSG_ATTR_POL_FMT(extack, attr, pol, fmt, args...) do { \ 166 struct netlink_ext_ack *__extack = (extack); \ 167 \ 168 if (!__extack) \ 169 break; \ 170 \ 171 if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \ 172 "%s" fmt "%s", "", ##args, "") >= \ 173 NETLINK_MAX_FMTMSG_LEN) \ 174 net_warn_ratelimited("%s" fmt "%s", "truncated extack: ", \ 175 ##args, "\n"); \ 176 \ 177 do_trace_netlink_extack(__extack->_msg_buf); \ 178 \ 179 __extack->_msg = __extack->_msg_buf; \ 180 __extack->bad_attr = (attr); \ 181 __extack->policy = (pol); \ 182} while (0) 183 184#define NL_SET_ERR_MSG_ATTR(extack, attr, msg) \ 185 NL_SET_ERR_MSG_ATTR_POL(extack, attr, NULL, msg) 186 187#define NL_SET_ERR_MSG_ATTR_FMT(extack, attr, msg, args...) \ 188 NL_SET_ERR_MSG_ATTR_POL_FMT(extack, attr, NULL, msg, ##args) 189 190#define NL_SET_ERR_ATTR_MISS(extack, nest, type) do { \ 191 struct netlink_ext_ack *__extack = (extack); \ 192 \ 193 if (__extack) { \ 194 __extack->miss_nest = (nest); \ 195 __extack->miss_type = (type); \ 196 } \ 197} while (0) 198 199#define NL_REQ_ATTR_CHECK(extack, nest, tb, type) ({ \ 200 struct nlattr **__tb = (tb); \ 201 u32 __attr = (type); \ 202 int __retval; \ 203 \ 204 __retval = !__tb[__attr]; \ 205 if (__retval) \ 206 NL_SET_ERR_ATTR_MISS((extack), (nest), __attr); \ 207 __retval; \ 208}) 209 210static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack, 211 u64 cookie) 212{ 213 if (!extack) 214 return; 215 memcpy(extack->cookie, &cookie, sizeof(cookie)); 216 extack->cookie_len = sizeof(cookie); 217} 218 219void netlink_kernel_release(struct sock *sk); 220int __netlink_change_ngroups(struct sock *sk, unsigned int groups); 221int netlink_change_ngroups(struct sock *sk, unsigned int groups); 222void __netlink_clear_multicast_users(struct sock *sk, unsigned int group); 223void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err, 224 const struct netlink_ext_ack *extack); 225int netlink_has_listeners(struct sock *sk, unsigned int group); 226bool netlink_strict_get_check(struct sk_buff *skb); 227 228int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock); 229int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid, 230 __u32 group, gfp_t allocation); 231 232typedef int (*netlink_filter_fn)(struct sock *dsk, struct sk_buff *skb, void *data); 233 234int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb, 235 __u32 portid, __u32 group, gfp_t allocation, 236 netlink_filter_fn filter, 237 void *filter_data); 238int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code); 239int netlink_register_notifier(struct notifier_block *nb); 240int netlink_unregister_notifier(struct notifier_block *nb); 241 242/* finegrained unicast helpers: */ 243struct sock *netlink_getsockbyfilp(struct file *filp); 244int netlink_attachskb(struct sock *sk, struct sk_buff *skb, 245 long *timeo, struct sock *ssk); 246void netlink_detachskb(struct sock *sk, struct sk_buff *skb); 247int netlink_sendskb(struct sock *sk, struct sk_buff *skb); 248 249static inline struct sk_buff * 250netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask) 251{ 252 struct sk_buff *nskb; 253 254 nskb = skb_clone(skb, gfp_mask); 255 if (!nskb) 256 return NULL; 257 258 /* This is a large skb, set destructor callback to release head */ 259 if (is_vmalloc_addr(skb->head)) 260 nskb->destructor = skb->destructor; 261 262 return nskb; 263} 264 265/* 266 * skb should fit one page. This choice is good for headerless malloc. 267 * But we should limit to 8K so that userspace does not have to 268 * use enormous buffer sizes on recvmsg() calls just to avoid 269 * MSG_TRUNC when PAGE_SIZE is very large. 270 */ 271#if PAGE_SIZE < 8192UL 272#define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(PAGE_SIZE) 273#else 274#define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(8192UL) 275#endif 276 277#define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN) 278 279 280struct netlink_callback { 281 struct sk_buff *skb; 282 const struct nlmsghdr *nlh; 283 int (*dump)(struct sk_buff * skb, 284 struct netlink_callback *cb); 285 int (*done)(struct netlink_callback *cb); 286 void *data; 287 /* the module that dump function belong to */ 288 struct module *module; 289 struct netlink_ext_ack *extack; 290 u16 family; 291 u16 answer_flags; 292 u32 min_dump_alloc; 293 unsigned int prev_seq, seq; 294 int flags; 295 bool strict_check; 296 union { 297 u8 ctx[48]; 298 299 /* args is deprecated. Cast a struct over ctx instead 300 * for proper type safety. 301 */ 302 long args[6]; 303 }; 304}; 305 306#define NL_ASSERT_DUMP_CTX_FITS(type_name) \ 307 BUILD_BUG_ON(sizeof(type_name) > \ 308 sizeof_field(struct netlink_callback, ctx)) 309 310struct netlink_notify { 311 struct net *net; 312 u32 portid; 313 int protocol; 314}; 315 316struct nlmsghdr * 317__nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags); 318 319struct netlink_dump_control { 320 int (*start)(struct netlink_callback *); 321 int (*dump)(struct sk_buff *skb, struct netlink_callback *); 322 int (*done)(struct netlink_callback *); 323 struct netlink_ext_ack *extack; 324 void *data; 325 struct module *module; 326 u32 min_dump_alloc; 327 int flags; 328}; 329 330int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 331 const struct nlmsghdr *nlh, 332 struct netlink_dump_control *control); 333static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 334 const struct nlmsghdr *nlh, 335 struct netlink_dump_control *control) 336{ 337 if (!control->module) 338 control->module = THIS_MODULE; 339 340 return __netlink_dump_start(ssk, skb, nlh, control); 341} 342 343struct netlink_tap { 344 struct net_device *dev; 345 struct module *module; 346 struct list_head list; 347}; 348 349int netlink_add_tap(struct netlink_tap *nt); 350int netlink_remove_tap(struct netlink_tap *nt); 351 352bool __netlink_ns_capable(const struct netlink_skb_parms *nsp, 353 struct user_namespace *ns, int cap); 354bool netlink_ns_capable(const struct sk_buff *skb, 355 struct user_namespace *ns, int cap); 356bool netlink_capable(const struct sk_buff *skb, int cap); 357bool netlink_net_capable(const struct sk_buff *skb, int cap); 358struct sk_buff *netlink_alloc_large_skb(unsigned int size, int broadcast); 359 360#endif /* __LINUX_NETLINK_H */ 361