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 static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb) 15 { 16 return (struct nlmsghdr *)skb->data; 17 } 18 19 enum netlink_skb_flags { 20 NETLINK_SKB_DST = 0x8, /* Dst set in sendto or sendmsg */ 21 }; 22 23 struct netlink_skb_parms { 24 struct scm_creds creds; /* Skb credentials */ 25 __u32 portid; 26 __u32 dst_group; 27 __u32 flags; 28 struct sock *sk; 29 bool nsid_is_set; 30 int nsid; 31 }; 32 33 #define NETLINK_CB(skb) (*(struct netlink_skb_parms*)&((skb)->cb)) 34 #define NETLINK_CREDS(skb) (&NETLINK_CB((skb)).creds) 35 36 37 void netlink_table_grab(void); 38 void netlink_table_ungrab(void); 39 40 #define NL_CFG_F_NONROOT_RECV (1 << 0) 41 #define NL_CFG_F_NONROOT_SEND (1 << 1) 42 43 /* optional Netlink kernel configuration parameters */ 44 struct netlink_kernel_cfg { 45 unsigned int groups; 46 unsigned int flags; 47 void (*input)(struct sk_buff *skb); 48 struct mutex *cb_mutex; 49 int (*bind)(struct net *net, int group); 50 void (*unbind)(struct net *net, int group); 51 bool (*compare)(struct net *net, struct sock *sk); 52 }; 53 54 struct sock *__netlink_kernel_create(struct net *net, int unit, 55 struct module *module, 56 struct netlink_kernel_cfg *cfg); 57 static inline struct sock * 58 netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg) 59 { 60 return __netlink_kernel_create(net, unit, THIS_MODULE, cfg); 61 } 62 63 /* this can be increased when necessary - don't expose to userland */ 64 #define NETLINK_MAX_COOKIE_LEN 20 65 66 /** 67 * struct netlink_ext_ack - netlink extended ACK report struct 68 * @_msg: message string to report - don't access directly, use 69 * %NL_SET_ERR_MSG 70 * @bad_attr: attribute with error 71 * @policy: policy for a bad attribute 72 * @cookie: cookie data to return to userspace (for success) 73 * @cookie_len: actual cookie data length 74 */ 75 struct netlink_ext_ack { 76 const char *_msg; 77 const struct nlattr *bad_attr; 78 const struct nla_policy *policy; 79 u8 cookie[NETLINK_MAX_COOKIE_LEN]; 80 u8 cookie_len; 81 }; 82 83 /* Always use this macro, this allows later putting the 84 * message into a separate section or such for things 85 * like translation or listing all possible messages. 86 * Currently string formatting is not supported (due 87 * to the lack of an output buffer.) 88 */ 89 #define NL_SET_ERR_MSG(extack, msg) do { \ 90 static const char __msg[] = msg; \ 91 struct netlink_ext_ack *__extack = (extack); \ 92 \ 93 if (__extack) \ 94 __extack->_msg = __msg; \ 95 } while (0) 96 97 #define NL_SET_ERR_MSG_MOD(extack, msg) \ 98 NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg) 99 100 #define NL_SET_BAD_ATTR_POLICY(extack, attr, pol) do { \ 101 if ((extack)) { \ 102 (extack)->bad_attr = (attr); \ 103 (extack)->policy = (pol); \ 104 } \ 105 } while (0) 106 107 #define NL_SET_BAD_ATTR(extack, attr) NL_SET_BAD_ATTR_POLICY(extack, attr, NULL) 108 109 #define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) do { \ 110 static const char __msg[] = msg; \ 111 struct netlink_ext_ack *__extack = (extack); \ 112 \ 113 if (__extack) { \ 114 __extack->_msg = __msg; \ 115 __extack->bad_attr = (attr); \ 116 __extack->policy = (pol); \ 117 } \ 118 } while (0) 119 120 #define NL_SET_ERR_MSG_ATTR(extack, attr, msg) \ 121 NL_SET_ERR_MSG_ATTR_POL(extack, attr, NULL, msg) 122 123 static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack, 124 u64 cookie) 125 { 126 u64 __cookie = cookie; 127 128 if (!extack) 129 return; 130 memcpy(extack->cookie, &__cookie, sizeof(__cookie)); 131 extack->cookie_len = sizeof(__cookie); 132 } 133 134 static inline void nl_set_extack_cookie_u32(struct netlink_ext_ack *extack, 135 u32 cookie) 136 { 137 u32 __cookie = cookie; 138 139 if (!extack) 140 return; 141 memcpy(extack->cookie, &__cookie, sizeof(__cookie)); 142 extack->cookie_len = sizeof(__cookie); 143 } 144 145 void netlink_kernel_release(struct sock *sk); 146 int __netlink_change_ngroups(struct sock *sk, unsigned int groups); 147 int netlink_change_ngroups(struct sock *sk, unsigned int groups); 148 void __netlink_clear_multicast_users(struct sock *sk, unsigned int group); 149 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err, 150 const struct netlink_ext_ack *extack); 151 int netlink_has_listeners(struct sock *sk, unsigned int group); 152 bool netlink_strict_get_check(struct sk_buff *skb); 153 154 int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock); 155 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid, 156 __u32 group, gfp_t allocation); 157 int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb, 158 __u32 portid, __u32 group, gfp_t allocation, 159 int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data), 160 void *filter_data); 161 int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code); 162 int netlink_register_notifier(struct notifier_block *nb); 163 int netlink_unregister_notifier(struct notifier_block *nb); 164 165 /* finegrained unicast helpers: */ 166 struct sock *netlink_getsockbyfilp(struct file *filp); 167 int netlink_attachskb(struct sock *sk, struct sk_buff *skb, 168 long *timeo, struct sock *ssk); 169 void netlink_detachskb(struct sock *sk, struct sk_buff *skb); 170 int netlink_sendskb(struct sock *sk, struct sk_buff *skb); 171 172 static inline struct sk_buff * 173 netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask) 174 { 175 struct sk_buff *nskb; 176 177 nskb = skb_clone(skb, gfp_mask); 178 if (!nskb) 179 return NULL; 180 181 /* This is a large skb, set destructor callback to release head */ 182 if (is_vmalloc_addr(skb->head)) 183 nskb->destructor = skb->destructor; 184 185 return nskb; 186 } 187 188 /* 189 * skb should fit one page. This choice is good for headerless malloc. 190 * But we should limit to 8K so that userspace does not have to 191 * use enormous buffer sizes on recvmsg() calls just to avoid 192 * MSG_TRUNC when PAGE_SIZE is very large. 193 */ 194 #if PAGE_SIZE < 8192UL 195 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(PAGE_SIZE) 196 #else 197 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(8192UL) 198 #endif 199 200 #define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN) 201 202 203 struct netlink_callback { 204 struct sk_buff *skb; 205 const struct nlmsghdr *nlh; 206 int (*dump)(struct sk_buff * skb, 207 struct netlink_callback *cb); 208 int (*done)(struct netlink_callback *cb); 209 void *data; 210 /* the module that dump function belong to */ 211 struct module *module; 212 struct netlink_ext_ack *extack; 213 u16 family; 214 u16 answer_flags; 215 u32 min_dump_alloc; 216 unsigned int prev_seq, seq; 217 bool strict_check; 218 union { 219 u8 ctx[48]; 220 221 /* args is deprecated. Cast a struct over ctx instead 222 * for proper type safety. 223 */ 224 long args[6]; 225 }; 226 }; 227 228 struct netlink_notify { 229 struct net *net; 230 u32 portid; 231 int protocol; 232 }; 233 234 struct nlmsghdr * 235 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags); 236 237 struct netlink_dump_control { 238 int (*start)(struct netlink_callback *); 239 int (*dump)(struct sk_buff *skb, struct netlink_callback *); 240 int (*done)(struct netlink_callback *); 241 void *data; 242 struct module *module; 243 u32 min_dump_alloc; 244 }; 245 246 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 247 const struct nlmsghdr *nlh, 248 struct netlink_dump_control *control); 249 static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 250 const struct nlmsghdr *nlh, 251 struct netlink_dump_control *control) 252 { 253 if (!control->module) 254 control->module = THIS_MODULE; 255 256 return __netlink_dump_start(ssk, skb, nlh, control); 257 } 258 259 struct netlink_tap { 260 struct net_device *dev; 261 struct module *module; 262 struct list_head list; 263 }; 264 265 int netlink_add_tap(struct netlink_tap *nt); 266 int netlink_remove_tap(struct netlink_tap *nt); 267 268 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp, 269 struct user_namespace *ns, int cap); 270 bool netlink_ns_capable(const struct sk_buff *skb, 271 struct user_namespace *ns, int cap); 272 bool netlink_capable(const struct sk_buff *skb, int cap); 273 bool netlink_net_capable(const struct sk_buff *skb, int cap); 274 275 #endif /* __LINUX_NETLINK_H */ 276