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
nlmsg_hdr(const struct sk_buff * skb)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 *
netlink_kernel_create(struct net * net,int unit,struct netlink_kernel_cfg * cfg)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
nl_set_extack_cookie_u64(struct netlink_ext_ack * extack,u64 cookie)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
nl_set_extack_cookie_u32(struct netlink_ext_ack * extack,u32 cookie)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 *
netlink_skb_clone(struct sk_buff * skb,gfp_t gfp_mask)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);
netlink_dump_start(struct sock * ssk,struct sk_buff * skb,const struct nlmsghdr * nlh,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