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 * @cookie: cookie data to return to userspace (for success) 72 * @cookie_len: actual cookie data length 73 */ 74 struct netlink_ext_ack { 75 const char *_msg; 76 const struct nlattr *bad_attr; 77 u8 cookie[NETLINK_MAX_COOKIE_LEN]; 78 u8 cookie_len; 79 }; 80 81 /* Always use this macro, this allows later putting the 82 * message into a separate section or such for things 83 * like translation or listing all possible messages. 84 * Currently string formatting is not supported (due 85 * to the lack of an output buffer.) 86 */ 87 #define NL_SET_ERR_MSG(extack, msg) do { \ 88 static const char __msg[] = msg; \ 89 struct netlink_ext_ack *__extack = (extack); \ 90 \ 91 if (__extack) \ 92 __extack->_msg = __msg; \ 93 } while (0) 94 95 #define NL_SET_ERR_MSG_MOD(extack, msg) \ 96 NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg) 97 98 #define NL_SET_BAD_ATTR(extack, attr) do { \ 99 if ((extack)) \ 100 (extack)->bad_attr = (attr); \ 101 } while (0) 102 103 #define NL_SET_ERR_MSG_ATTR(extack, attr, msg) do { \ 104 static const char __msg[] = msg; \ 105 struct netlink_ext_ack *__extack = (extack); \ 106 \ 107 if (__extack) { \ 108 __extack->_msg = __msg; \ 109 __extack->bad_attr = (attr); \ 110 } \ 111 } while (0) 112 113 static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack, 114 u64 cookie) 115 { 116 u64 __cookie = cookie; 117 118 memcpy(extack->cookie, &__cookie, sizeof(__cookie)); 119 extack->cookie_len = sizeof(__cookie); 120 } 121 122 void netlink_kernel_release(struct sock *sk); 123 int __netlink_change_ngroups(struct sock *sk, unsigned int groups); 124 int netlink_change_ngroups(struct sock *sk, unsigned int groups); 125 void __netlink_clear_multicast_users(struct sock *sk, unsigned int group); 126 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err, 127 const struct netlink_ext_ack *extack); 128 int netlink_has_listeners(struct sock *sk, unsigned int group); 129 130 int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock); 131 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid, 132 __u32 group, gfp_t allocation); 133 int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb, 134 __u32 portid, __u32 group, gfp_t allocation, 135 int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data), 136 void *filter_data); 137 int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code); 138 int netlink_register_notifier(struct notifier_block *nb); 139 int netlink_unregister_notifier(struct notifier_block *nb); 140 141 /* finegrained unicast helpers: */ 142 struct sock *netlink_getsockbyfilp(struct file *filp); 143 int netlink_attachskb(struct sock *sk, struct sk_buff *skb, 144 long *timeo, struct sock *ssk); 145 void netlink_detachskb(struct sock *sk, struct sk_buff *skb); 146 int netlink_sendskb(struct sock *sk, struct sk_buff *skb); 147 148 static inline struct sk_buff * 149 netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask) 150 { 151 struct sk_buff *nskb; 152 153 nskb = skb_clone(skb, gfp_mask); 154 if (!nskb) 155 return NULL; 156 157 /* This is a large skb, set destructor callback to release head */ 158 if (is_vmalloc_addr(skb->head)) 159 nskb->destructor = skb->destructor; 160 161 return nskb; 162 } 163 164 /* 165 * skb should fit one page. This choice is good for headerless malloc. 166 * But we should limit to 8K so that userspace does not have to 167 * use enormous buffer sizes on recvmsg() calls just to avoid 168 * MSG_TRUNC when PAGE_SIZE is very large. 169 */ 170 #if PAGE_SIZE < 8192UL 171 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(PAGE_SIZE) 172 #else 173 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(8192UL) 174 #endif 175 176 #define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN) 177 178 179 struct netlink_callback { 180 struct sk_buff *skb; 181 const struct nlmsghdr *nlh; 182 int (*dump)(struct sk_buff * skb, 183 struct netlink_callback *cb); 184 int (*done)(struct netlink_callback *cb); 185 void *data; 186 /* the module that dump function belong to */ 187 struct module *module; 188 struct netlink_ext_ack *extack; 189 u16 family; 190 u16 min_dump_alloc; 191 bool strict_check; 192 u16 answer_flags; 193 unsigned int prev_seq, seq; 194 long args[6]; 195 }; 196 197 struct netlink_notify { 198 struct net *net; 199 u32 portid; 200 int protocol; 201 }; 202 203 struct nlmsghdr * 204 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags); 205 206 struct netlink_dump_control { 207 int (*start)(struct netlink_callback *); 208 int (*dump)(struct sk_buff *skb, struct netlink_callback *); 209 int (*done)(struct netlink_callback *); 210 void *data; 211 struct module *module; 212 u16 min_dump_alloc; 213 }; 214 215 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 216 const struct nlmsghdr *nlh, 217 struct netlink_dump_control *control); 218 static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 219 const struct nlmsghdr *nlh, 220 struct netlink_dump_control *control) 221 { 222 if (!control->module) 223 control->module = THIS_MODULE; 224 225 return __netlink_dump_start(ssk, skb, nlh, control); 226 } 227 228 struct netlink_tap { 229 struct net_device *dev; 230 struct module *module; 231 struct list_head list; 232 }; 233 234 int netlink_add_tap(struct netlink_tap *nt); 235 int netlink_remove_tap(struct netlink_tap *nt); 236 237 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp, 238 struct user_namespace *ns, int cap); 239 bool netlink_ns_capable(const struct sk_buff *skb, 240 struct user_namespace *ns, int cap); 241 bool netlink_capable(const struct sk_buff *skb, int cap); 242 bool netlink_net_capable(const struct sk_buff *skb, int cap); 243 244 #endif /* __LINUX_NETLINK_H */ 245