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