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 extern void netlink_table_grab(void);
38 extern 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 extern 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 * @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 extern void netlink_kernel_release(struct sock *sk);
114 extern int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
115 extern int netlink_change_ngroups(struct sock *sk, unsigned int groups);
116 extern void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
117 extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
118 const struct netlink_ext_ack *extack);
119 extern int netlink_has_listeners(struct sock *sk, unsigned int group);
120
121 extern int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
122 extern int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
123 __u32 group, gfp_t allocation);
124 extern int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
125 __u32 portid, __u32 group, gfp_t allocation,
126 int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
127 void *filter_data);
128 extern int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
129 extern int netlink_register_notifier(struct notifier_block *nb);
130 extern int netlink_unregister_notifier(struct notifier_block *nb);
131
132 /* finegrained unicast helpers: */
133 struct sock *netlink_getsockbyfilp(struct file *filp);
134 int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
135 long *timeo, struct sock *ssk);
136 void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
137 int netlink_sendskb(struct sock *sk, struct sk_buff *skb);
138
139 static inline struct sk_buff *
netlink_skb_clone(struct sk_buff * skb,gfp_t gfp_mask)140 netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
141 {
142 struct sk_buff *nskb;
143
144 nskb = skb_clone(skb, gfp_mask);
145 if (!nskb)
146 return NULL;
147
148 /* This is a large skb, set destructor callback to release head */
149 if (is_vmalloc_addr(skb->head))
150 nskb->destructor = skb->destructor;
151
152 return nskb;
153 }
154
155 /*
156 * skb should fit one page. This choice is good for headerless malloc.
157 * But we should limit to 8K so that userspace does not have to
158 * use enormous buffer sizes on recvmsg() calls just to avoid
159 * MSG_TRUNC when PAGE_SIZE is very large.
160 */
161 #if PAGE_SIZE < 8192UL
162 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(PAGE_SIZE)
163 #else
164 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(8192UL)
165 #endif
166
167 #define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)
168
169
170 struct netlink_callback {
171 struct sk_buff *skb;
172 const struct nlmsghdr *nlh;
173 int (*dump)(struct sk_buff * skb,
174 struct netlink_callback *cb);
175 int (*done)(struct netlink_callback *cb);
176 void *data;
177 /* the module that dump function belong to */
178 struct module *module;
179 u16 family;
180 u16 min_dump_alloc;
181 unsigned int prev_seq, seq;
182 long args[6];
183 };
184
185 struct netlink_notify {
186 struct net *net;
187 u32 portid;
188 int protocol;
189 };
190
191 struct nlmsghdr *
192 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);
193
194 struct netlink_dump_control {
195 int (*start)(struct netlink_callback *);
196 int (*dump)(struct sk_buff *skb, struct netlink_callback *);
197 int (*done)(struct netlink_callback *);
198 void *data;
199 struct module *module;
200 u16 min_dump_alloc;
201 };
202
203 extern int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
204 const struct nlmsghdr *nlh,
205 struct netlink_dump_control *control);
netlink_dump_start(struct sock * ssk,struct sk_buff * skb,const struct nlmsghdr * nlh,struct netlink_dump_control * control)206 static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
207 const struct nlmsghdr *nlh,
208 struct netlink_dump_control *control)
209 {
210 if (!control->module)
211 control->module = THIS_MODULE;
212
213 return __netlink_dump_start(ssk, skb, nlh, control);
214 }
215
216 struct netlink_tap {
217 struct net_device *dev;
218 struct module *module;
219 struct list_head list;
220 };
221
222 extern int netlink_add_tap(struct netlink_tap *nt);
223 extern int netlink_remove_tap(struct netlink_tap *nt);
224
225 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
226 struct user_namespace *ns, int cap);
227 bool netlink_ns_capable(const struct sk_buff *skb,
228 struct user_namespace *ns, int cap);
229 bool netlink_capable(const struct sk_buff *skb, int cap);
230 bool netlink_net_capable(const struct sk_buff *skb, int cap);
231
232 #endif /* __LINUX_NETLINK_H */
233