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_BAD_ATTR_POLICY(extack, attr, pol) do { \ 134 if ((extack)) { \ 135 (extack)->bad_attr = (attr); \ 136 (extack)->policy = (pol); \ 137 } \ 138 } while (0) 139 140 #define NL_SET_BAD_ATTR(extack, attr) NL_SET_BAD_ATTR_POLICY(extack, attr, NULL) 141 142 #define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) do { \ 143 static const char __msg[] = msg; \ 144 struct netlink_ext_ack *__extack = (extack); \ 145 \ 146 do_trace_netlink_extack(__msg); \ 147 \ 148 if (__extack) { \ 149 __extack->_msg = __msg; \ 150 __extack->bad_attr = (attr); \ 151 __extack->policy = (pol); \ 152 } \ 153 } while (0) 154 155 #define NL_SET_ERR_MSG_ATTR(extack, attr, msg) \ 156 NL_SET_ERR_MSG_ATTR_POL(extack, attr, NULL, msg) 157 158 #define NL_SET_ERR_ATTR_MISS(extack, nest, type) do { \ 159 struct netlink_ext_ack *__extack = (extack); \ 160 \ 161 if (__extack) { \ 162 __extack->miss_nest = (nest); \ 163 __extack->miss_type = (type); \ 164 } \ 165 } while (0) 166 167 #define NL_REQ_ATTR_CHECK(extack, nest, tb, type) ({ \ 168 struct nlattr **__tb = (tb); \ 169 u32 __attr = (type); \ 170 int __retval; \ 171 \ 172 __retval = !__tb[__attr]; \ 173 if (__retval) \ 174 NL_SET_ERR_ATTR_MISS((extack), (nest), __attr); \ 175 __retval; \ 176 }) 177 178 static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack, 179 u64 cookie) 180 { 181 if (!extack) 182 return; 183 memcpy(extack->cookie, &cookie, sizeof(cookie)); 184 extack->cookie_len = sizeof(cookie); 185 } 186 187 void netlink_kernel_release(struct sock *sk); 188 int __netlink_change_ngroups(struct sock *sk, unsigned int groups); 189 int netlink_change_ngroups(struct sock *sk, unsigned int groups); 190 void __netlink_clear_multicast_users(struct sock *sk, unsigned int group); 191 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err, 192 const struct netlink_ext_ack *extack); 193 int netlink_has_listeners(struct sock *sk, unsigned int group); 194 bool netlink_strict_get_check(struct sk_buff *skb); 195 196 int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock); 197 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid, 198 __u32 group, gfp_t allocation); 199 int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code); 200 int netlink_register_notifier(struct notifier_block *nb); 201 int netlink_unregister_notifier(struct notifier_block *nb); 202 203 /* finegrained unicast helpers: */ 204 struct sock *netlink_getsockbyfilp(struct file *filp); 205 int netlink_attachskb(struct sock *sk, struct sk_buff *skb, 206 long *timeo, struct sock *ssk); 207 void netlink_detachskb(struct sock *sk, struct sk_buff *skb); 208 int netlink_sendskb(struct sock *sk, struct sk_buff *skb); 209 210 static inline struct sk_buff * 211 netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask) 212 { 213 struct sk_buff *nskb; 214 215 nskb = skb_clone(skb, gfp_mask); 216 if (!nskb) 217 return NULL; 218 219 /* This is a large skb, set destructor callback to release head */ 220 if (is_vmalloc_addr(skb->head)) 221 nskb->destructor = skb->destructor; 222 223 return nskb; 224 } 225 226 /* 227 * skb should fit one page. This choice is good for headerless malloc. 228 * But we should limit to 8K so that userspace does not have to 229 * use enormous buffer sizes on recvmsg() calls just to avoid 230 * MSG_TRUNC when PAGE_SIZE is very large. 231 */ 232 #if PAGE_SIZE < 8192UL 233 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(PAGE_SIZE) 234 #else 235 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(8192UL) 236 #endif 237 238 #define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN) 239 240 241 struct netlink_callback { 242 struct sk_buff *skb; 243 const struct nlmsghdr *nlh; 244 int (*dump)(struct sk_buff * skb, 245 struct netlink_callback *cb); 246 int (*done)(struct netlink_callback *cb); 247 void *data; 248 /* the module that dump function belong to */ 249 struct module *module; 250 struct netlink_ext_ack *extack; 251 u16 family; 252 u16 answer_flags; 253 u32 min_dump_alloc; 254 unsigned int prev_seq, seq; 255 bool strict_check; 256 union { 257 u8 ctx[48]; 258 259 /* args is deprecated. Cast a struct over ctx instead 260 * for proper type safety. 261 */ 262 long args[6]; 263 }; 264 }; 265 266 struct netlink_notify { 267 struct net *net; 268 u32 portid; 269 int protocol; 270 }; 271 272 struct nlmsghdr * 273 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags); 274 275 struct netlink_dump_control { 276 int (*start)(struct netlink_callback *); 277 int (*dump)(struct sk_buff *skb, struct netlink_callback *); 278 int (*done)(struct netlink_callback *); 279 void *data; 280 struct module *module; 281 u32 min_dump_alloc; 282 }; 283 284 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 285 const struct nlmsghdr *nlh, 286 struct netlink_dump_control *control); 287 static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 288 const struct nlmsghdr *nlh, 289 struct netlink_dump_control *control) 290 { 291 if (!control->module) 292 control->module = THIS_MODULE; 293 294 return __netlink_dump_start(ssk, skb, nlh, control); 295 } 296 297 struct netlink_tap { 298 struct net_device *dev; 299 struct module *module; 300 struct list_head list; 301 }; 302 303 int netlink_add_tap(struct netlink_tap *nt); 304 int netlink_remove_tap(struct netlink_tap *nt); 305 306 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp, 307 struct user_namespace *ns, int cap); 308 bool netlink_ns_capable(const struct sk_buff *skb, 309 struct user_namespace *ns, int cap); 310 bool netlink_capable(const struct sk_buff *skb, int cap); 311 bool netlink_net_capable(const struct sk_buff *skb, int cap); 312 313 #endif /* __LINUX_NETLINK_H */ 314