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 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 struct mutex *cb_mutex; 51 int (*bind)(struct net *net, int group); 52 void (*unbind)(struct net *net, int group); 53 bool (*compare)(struct net *net, struct sock *sk); 54 }; 55 56 struct sock *__netlink_kernel_create(struct net *net, int unit, 57 struct module *module, 58 struct netlink_kernel_cfg *cfg); 59 static inline struct sock * 60 netlink_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 */ 82 struct 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(extack, attr, msg) \ 166 NL_SET_ERR_MSG_ATTR_POL(extack, attr, NULL, msg) 167 168 #define NL_SET_ERR_ATTR_MISS(extack, nest, type) do { \ 169 struct netlink_ext_ack *__extack = (extack); \ 170 \ 171 if (__extack) { \ 172 __extack->miss_nest = (nest); \ 173 __extack->miss_type = (type); \ 174 } \ 175 } while (0) 176 177 #define NL_REQ_ATTR_CHECK(extack, nest, tb, type) ({ \ 178 struct nlattr **__tb = (tb); \ 179 u32 __attr = (type); \ 180 int __retval; \ 181 \ 182 __retval = !__tb[__attr]; \ 183 if (__retval) \ 184 NL_SET_ERR_ATTR_MISS((extack), (nest), __attr); \ 185 __retval; \ 186 }) 187 188 static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack, 189 u64 cookie) 190 { 191 if (!extack) 192 return; 193 memcpy(extack->cookie, &cookie, sizeof(cookie)); 194 extack->cookie_len = sizeof(cookie); 195 } 196 197 void netlink_kernel_release(struct sock *sk); 198 int __netlink_change_ngroups(struct sock *sk, unsigned int groups); 199 int netlink_change_ngroups(struct sock *sk, unsigned int groups); 200 void __netlink_clear_multicast_users(struct sock *sk, unsigned int group); 201 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err, 202 const struct netlink_ext_ack *extack); 203 int netlink_has_listeners(struct sock *sk, unsigned int group); 204 bool netlink_strict_get_check(struct sk_buff *skb); 205 206 int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock); 207 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid, 208 __u32 group, gfp_t allocation); 209 int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code); 210 int netlink_register_notifier(struct notifier_block *nb); 211 int netlink_unregister_notifier(struct notifier_block *nb); 212 213 /* finegrained unicast helpers: */ 214 struct sock *netlink_getsockbyfilp(struct file *filp); 215 int netlink_attachskb(struct sock *sk, struct sk_buff *skb, 216 long *timeo, struct sock *ssk); 217 void netlink_detachskb(struct sock *sk, struct sk_buff *skb); 218 int netlink_sendskb(struct sock *sk, struct sk_buff *skb); 219 220 static inline struct sk_buff * 221 netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask) 222 { 223 struct sk_buff *nskb; 224 225 nskb = skb_clone(skb, gfp_mask); 226 if (!nskb) 227 return NULL; 228 229 /* This is a large skb, set destructor callback to release head */ 230 if (is_vmalloc_addr(skb->head)) 231 nskb->destructor = skb->destructor; 232 233 return nskb; 234 } 235 236 /* 237 * skb should fit one page. This choice is good for headerless malloc. 238 * But we should limit to 8K so that userspace does not have to 239 * use enormous buffer sizes on recvmsg() calls just to avoid 240 * MSG_TRUNC when PAGE_SIZE is very large. 241 */ 242 #if PAGE_SIZE < 8192UL 243 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(PAGE_SIZE) 244 #else 245 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(8192UL) 246 #endif 247 248 #define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN) 249 250 251 struct netlink_callback { 252 struct sk_buff *skb; 253 const struct nlmsghdr *nlh; 254 int (*dump)(struct sk_buff * skb, 255 struct netlink_callback *cb); 256 int (*done)(struct netlink_callback *cb); 257 void *data; 258 /* the module that dump function belong to */ 259 struct module *module; 260 struct netlink_ext_ack *extack; 261 u16 family; 262 u16 answer_flags; 263 u32 min_dump_alloc; 264 unsigned int prev_seq, seq; 265 bool strict_check; 266 union { 267 u8 ctx[48]; 268 269 /* args is deprecated. Cast a struct over ctx instead 270 * for proper type safety. 271 */ 272 long args[6]; 273 }; 274 }; 275 276 #define NL_ASSERT_DUMP_CTX_FITS(type_name) \ 277 BUILD_BUG_ON(sizeof(type_name) > \ 278 sizeof_field(struct netlink_callback, ctx)) 279 280 struct netlink_notify { 281 struct net *net; 282 u32 portid; 283 int protocol; 284 }; 285 286 struct nlmsghdr * 287 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags); 288 289 struct netlink_dump_control { 290 int (*start)(struct netlink_callback *); 291 int (*dump)(struct sk_buff *skb, struct netlink_callback *); 292 int (*done)(struct netlink_callback *); 293 void *data; 294 struct module *module; 295 u32 min_dump_alloc; 296 }; 297 298 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 299 const struct nlmsghdr *nlh, 300 struct netlink_dump_control *control); 301 static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 302 const struct nlmsghdr *nlh, 303 struct netlink_dump_control *control) 304 { 305 if (!control->module) 306 control->module = THIS_MODULE; 307 308 return __netlink_dump_start(ssk, skb, nlh, control); 309 } 310 311 struct netlink_tap { 312 struct net_device *dev; 313 struct module *module; 314 struct list_head list; 315 }; 316 317 int netlink_add_tap(struct netlink_tap *nt); 318 int netlink_remove_tap(struct netlink_tap *nt); 319 320 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp, 321 struct user_namespace *ns, int cap); 322 bool netlink_ns_capable(const struct sk_buff *skb, 323 struct user_namespace *ns, int cap); 324 bool netlink_capable(const struct sk_buff *skb, int cap); 325 bool netlink_net_capable(const struct sk_buff *skb, int cap); 326 327 #endif /* __LINUX_NETLINK_H */ 328