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
12struct net;
13
14void do_trace_netlink_extack(const char *msg);
15
16static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb)
17{
18 return (struct nlmsghdr *)skb->data;
19}
20
21enum netlink_skb_flags {
22 NETLINK_SKB_DST = 0x8, /* Dst set in sendto or sendmsg */
23};
24
25struct 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
39void netlink_table_grab(void);
40void 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 */
46struct 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
56struct sock *__netlink_kernel_create(struct net *net, int unit,
57 struct module *module,
58 struct netlink_kernel_cfg *cfg);
59static inline struct sock *
60netlink_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 */
77struct 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
129static 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
138void netlink_kernel_release(struct sock *sk);
139int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
140int netlink_change_ngroups(struct sock *sk, unsigned int groups);
141void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
142void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
143 const struct netlink_ext_ack *extack);
144int netlink_has_listeners(struct sock *sk, unsigned int group);
145bool netlink_strict_get_check(struct sk_buff *skb);
146
147int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
148int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
149 __u32 group, gfp_t allocation);
150int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
151int netlink_register_notifier(struct notifier_block *nb);
152int netlink_unregister_notifier(struct notifier_block *nb);
153
154/* finegrained unicast helpers: */
155struct sock *netlink_getsockbyfilp(struct file *filp);
156int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
157 long *timeo, struct sock *ssk);
158void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
159int netlink_sendskb(struct sock *sk, struct sk_buff *skb);
160
161static inline struct sk_buff *
162netlink_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
192struct 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
217struct netlink_notify {
218 struct net *net;
219 u32 portid;
220 int protocol;
221};
222
223struct nlmsghdr *
224__nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);
225
226struct 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
235int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
236 const struct nlmsghdr *nlh,
237 struct netlink_dump_control *control);
238static 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
248struct netlink_tap {
249 struct net_device *dev;
250 struct module *module;
251 struct list_head list;
252};
253
254int netlink_add_tap(struct netlink_tap *nt);
255int netlink_remove_tap(struct netlink_tap *nt);
256
257bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
258 struct user_namespace *ns, int cap);
259bool netlink_ns_capable(const struct sk_buff *skb,
260 struct user_namespace *ns, int cap);
261bool netlink_capable(const struct sk_buff *skb, int cap);
262bool netlink_net_capable(const struct sk_buff *skb, int cap);
263
264#endif /* __LINUX_NETLINK_H */
265

source code of linux/include/linux/netlink.h