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 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 * @cookie: cookie data to return to userspace (for success) 75 * @cookie_len: actual cookie data length 76 */ 77 struct netlink_ext_ack { 78 const char *_msg; 79 const struct nlattr *bad_attr; 80 const struct nla_policy *policy; 81 u8 cookie[NETLINK_MAX_COOKIE_LEN]; 82 u8 cookie_len; 83 }; 84 85 /* Always use this macro, this allows later putting the 86 * message into a separate section or such for things 87 * like translation or listing all possible messages. 88 * Currently string formatting is not supported (due 89 * to the lack of an output buffer.) 90 */ 91 #define NL_SET_ERR_MSG(extack, msg) do { \ 92 static const char __msg[] = msg; \ 93 struct netlink_ext_ack *__extack = (extack); \ 94 \ 95 do_trace_netlink_extack(__msg); \ 96 \ 97 if (__extack) \ 98 __extack->_msg = __msg; \ 99 } while (0) 100 101 #define NL_SET_ERR_MSG_MOD(extack, msg) \ 102 NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg) 103 104 #define NL_SET_BAD_ATTR_POLICY(extack, attr, pol) do { \ 105 if ((extack)) { \ 106 (extack)->bad_attr = (attr); \ 107 (extack)->policy = (pol); \ 108 } \ 109 } while (0) 110 111 #define NL_SET_BAD_ATTR(extack, attr) NL_SET_BAD_ATTR_POLICY(extack, attr, NULL) 112 113 #define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) do { \ 114 static const char __msg[] = msg; \ 115 struct netlink_ext_ack *__extack = (extack); \ 116 \ 117 do_trace_netlink_extack(__msg); \ 118 \ 119 if (__extack) { \ 120 __extack->_msg = __msg; \ 121 __extack->bad_attr = (attr); \ 122 __extack->policy = (pol); \ 123 } \ 124 } while (0) 125 126 #define NL_SET_ERR_MSG_ATTR(extack, attr, msg) \ 127 NL_SET_ERR_MSG_ATTR_POL(extack, attr, NULL, msg) 128 129 static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack, 130 u64 cookie) 131 { 132 if (!extack) 133 return; 134 memcpy(extack->cookie, &cookie, sizeof(cookie)); 135 extack->cookie_len = sizeof(cookie); 136 } 137 138 static inline void nl_set_extack_cookie_u32(struct netlink_ext_ack *extack, 139 u32 cookie) 140 { 141 if (!extack) 142 return; 143 memcpy(extack->cookie, &cookie, sizeof(cookie)); 144 extack->cookie_len = sizeof(cookie); 145 } 146 147 void netlink_kernel_release(struct sock *sk); 148 int __netlink_change_ngroups(struct sock *sk, unsigned int groups); 149 int netlink_change_ngroups(struct sock *sk, unsigned int groups); 150 void __netlink_clear_multicast_users(struct sock *sk, unsigned int group); 151 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err, 152 const struct netlink_ext_ack *extack); 153 int netlink_has_listeners(struct sock *sk, unsigned int group); 154 bool netlink_strict_get_check(struct sk_buff *skb); 155 156 int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock); 157 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid, 158 __u32 group, gfp_t allocation); 159 int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code); 160 int netlink_register_notifier(struct notifier_block *nb); 161 int netlink_unregister_notifier(struct notifier_block *nb); 162 163 /* finegrained unicast helpers: */ 164 struct sock *netlink_getsockbyfilp(struct file *filp); 165 int netlink_attachskb(struct sock *sk, struct sk_buff *skb, 166 long *timeo, struct sock *ssk); 167 void netlink_detachskb(struct sock *sk, struct sk_buff *skb); 168 int netlink_sendskb(struct sock *sk, struct sk_buff *skb); 169 170 static inline struct sk_buff * 171 netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask) 172 { 173 struct sk_buff *nskb; 174 175 nskb = skb_clone(skb, gfp_mask); 176 if (!nskb) 177 return NULL; 178 179 /* This is a large skb, set destructor callback to release head */ 180 if (is_vmalloc_addr(skb->head)) 181 nskb->destructor = skb->destructor; 182 183 return nskb; 184 } 185 186 /* 187 * skb should fit one page. This choice is good for headerless malloc. 188 * But we should limit to 8K so that userspace does not have to 189 * use enormous buffer sizes on recvmsg() calls just to avoid 190 * MSG_TRUNC when PAGE_SIZE is very large. 191 */ 192 #if PAGE_SIZE < 8192UL 193 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(PAGE_SIZE) 194 #else 195 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(8192UL) 196 #endif 197 198 #define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN) 199 200 201 struct netlink_callback { 202 struct sk_buff *skb; 203 const struct nlmsghdr *nlh; 204 int (*dump)(struct sk_buff * skb, 205 struct netlink_callback *cb); 206 int (*done)(struct netlink_callback *cb); 207 void *data; 208 /* the module that dump function belong to */ 209 struct module *module; 210 struct netlink_ext_ack *extack; 211 u16 family; 212 u16 answer_flags; 213 u32 min_dump_alloc; 214 unsigned int prev_seq, seq; 215 bool strict_check; 216 union { 217 u8 ctx[48]; 218 219 /* args is deprecated. Cast a struct over ctx instead 220 * for proper type safety. 221 */ 222 long args[6]; 223 }; 224 }; 225 226 struct netlink_notify { 227 struct net *net; 228 u32 portid; 229 int protocol; 230 }; 231 232 struct nlmsghdr * 233 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags); 234 235 struct netlink_dump_control { 236 int (*start)(struct netlink_callback *); 237 int (*dump)(struct sk_buff *skb, struct netlink_callback *); 238 int (*done)(struct netlink_callback *); 239 void *data; 240 struct module *module; 241 u32 min_dump_alloc; 242 }; 243 244 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 245 const struct nlmsghdr *nlh, 246 struct netlink_dump_control *control); 247 static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 248 const struct nlmsghdr *nlh, 249 struct netlink_dump_control *control) 250 { 251 if (!control->module) 252 control->module = THIS_MODULE; 253 254 return __netlink_dump_start(ssk, skb, nlh, control); 255 } 256 257 struct netlink_tap { 258 struct net_device *dev; 259 struct module *module; 260 struct list_head list; 261 }; 262 263 int netlink_add_tap(struct netlink_tap *nt); 264 int netlink_remove_tap(struct netlink_tap *nt); 265 266 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp, 267 struct user_namespace *ns, int cap); 268 bool netlink_ns_capable(const struct sk_buff *skb, 269 struct user_namespace *ns, int cap); 270 bool netlink_capable(const struct sk_buff *skb, int cap); 271 bool netlink_net_capable(const struct sk_buff *skb, int cap); 272 273 #endif /* __LINUX_NETLINK_H */ 274