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