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 u64 __cookie = cookie; 133 134 if (!extack) 135 return; 136 memcpy(extack->cookie, &__cookie, sizeof(__cookie)); 137 extack->cookie_len = sizeof(__cookie); 138 } 139 140 static inline void nl_set_extack_cookie_u32(struct netlink_ext_ack *extack, 141 u32 cookie) 142 { 143 u32 __cookie = cookie; 144 145 if (!extack) 146 return; 147 memcpy(extack->cookie, &__cookie, sizeof(__cookie)); 148 extack->cookie_len = sizeof(__cookie); 149 } 150 151 void netlink_kernel_release(struct sock *sk); 152 int __netlink_change_ngroups(struct sock *sk, unsigned int groups); 153 int netlink_change_ngroups(struct sock *sk, unsigned int groups); 154 void __netlink_clear_multicast_users(struct sock *sk, unsigned int group); 155 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err, 156 const struct netlink_ext_ack *extack); 157 int netlink_has_listeners(struct sock *sk, unsigned int group); 158 bool netlink_strict_get_check(struct sk_buff *skb); 159 160 int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock); 161 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid, 162 __u32 group, gfp_t allocation); 163 int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb, 164 __u32 portid, __u32 group, gfp_t allocation, 165 int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data), 166 void *filter_data); 167 int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code); 168 int netlink_register_notifier(struct notifier_block *nb); 169 int netlink_unregister_notifier(struct notifier_block *nb); 170 171 /* finegrained unicast helpers: */ 172 struct sock *netlink_getsockbyfilp(struct file *filp); 173 int netlink_attachskb(struct sock *sk, struct sk_buff *skb, 174 long *timeo, struct sock *ssk); 175 void netlink_detachskb(struct sock *sk, struct sk_buff *skb); 176 int netlink_sendskb(struct sock *sk, struct sk_buff *skb); 177 178 static inline struct sk_buff * 179 netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask) 180 { 181 struct sk_buff *nskb; 182 183 nskb = skb_clone(skb, gfp_mask); 184 if (!nskb) 185 return NULL; 186 187 /* This is a large skb, set destructor callback to release head */ 188 if (is_vmalloc_addr(skb->head)) 189 nskb->destructor = skb->destructor; 190 191 return nskb; 192 } 193 194 /* 195 * skb should fit one page. This choice is good for headerless malloc. 196 * But we should limit to 8K so that userspace does not have to 197 * use enormous buffer sizes on recvmsg() calls just to avoid 198 * MSG_TRUNC when PAGE_SIZE is very large. 199 */ 200 #if PAGE_SIZE < 8192UL 201 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(PAGE_SIZE) 202 #else 203 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(8192UL) 204 #endif 205 206 #define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN) 207 208 209 struct netlink_callback { 210 struct sk_buff *skb; 211 const struct nlmsghdr *nlh; 212 int (*dump)(struct sk_buff * skb, 213 struct netlink_callback *cb); 214 int (*done)(struct netlink_callback *cb); 215 void *data; 216 /* the module that dump function belong to */ 217 struct module *module; 218 struct netlink_ext_ack *extack; 219 u16 family; 220 u16 answer_flags; 221 u32 min_dump_alloc; 222 unsigned int prev_seq, seq; 223 bool strict_check; 224 union { 225 u8 ctx[48]; 226 227 /* args is deprecated. Cast a struct over ctx instead 228 * for proper type safety. 229 */ 230 long args[6]; 231 }; 232 }; 233 234 struct netlink_notify { 235 struct net *net; 236 u32 portid; 237 int protocol; 238 }; 239 240 struct nlmsghdr * 241 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags); 242 243 struct netlink_dump_control { 244 int (*start)(struct netlink_callback *); 245 int (*dump)(struct sk_buff *skb, struct netlink_callback *); 246 int (*done)(struct netlink_callback *); 247 void *data; 248 struct module *module; 249 u32 min_dump_alloc; 250 }; 251 252 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 253 const struct nlmsghdr *nlh, 254 struct netlink_dump_control *control); 255 static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 256 const struct nlmsghdr *nlh, 257 struct netlink_dump_control *control) 258 { 259 if (!control->module) 260 control->module = THIS_MODULE; 261 262 return __netlink_dump_start(ssk, skb, nlh, control); 263 } 264 265 struct netlink_tap { 266 struct net_device *dev; 267 struct module *module; 268 struct list_head list; 269 }; 270 271 int netlink_add_tap(struct netlink_tap *nt); 272 int netlink_remove_tap(struct netlink_tap *nt); 273 274 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp, 275 struct user_namespace *ns, int cap); 276 bool netlink_ns_capable(const struct sk_buff *skb, 277 struct user_namespace *ns, int cap); 278 bool netlink_capable(const struct sk_buff *skb, int cap); 279 bool netlink_net_capable(const struct sk_buff *skb, int cap); 280 281 #endif /* __LINUX_NETLINK_H */ 282