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