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
14static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb)
15{
16 return (struct nlmsghdr *)skb->data;
17}
18
19enum netlink_skb_flags {
20 NETLINK_SKB_DST = 0x8, /* Dst set in sendto or sendmsg */
21};
22
23struct 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
37void netlink_table_grab(void);
38void 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 */
44struct 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
54struct sock *__netlink_kernel_create(struct net *net, int unit,
55 struct module *module,
56 struct netlink_kernel_cfg *cfg);
57static inline struct sock *
58netlink_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 */
74struct 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
113static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack,
114 u64 cookie)
115{
116 u64 __cookie = cookie;
117
118 memcpy(extack->cookie, &__cookie, sizeof(__cookie));
119 extack->cookie_len = sizeof(__cookie);
120}
121
122void netlink_kernel_release(struct sock *sk);
123int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
124int netlink_change_ngroups(struct sock *sk, unsigned int groups);
125void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
126void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
127 const struct netlink_ext_ack *extack);
128int netlink_has_listeners(struct sock *sk, unsigned int group);
129bool netlink_strict_get_check(struct sk_buff *skb);
130
131int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
132int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
133 __u32 group, gfp_t allocation);
134int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
135 __u32 portid, __u32 group, gfp_t allocation,
136 int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
137 void *filter_data);
138int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
139int netlink_register_notifier(struct notifier_block *nb);
140int netlink_unregister_notifier(struct notifier_block *nb);
141
142/* finegrained unicast helpers: */
143struct sock *netlink_getsockbyfilp(struct file *filp);
144int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
145 long *timeo, struct sock *ssk);
146void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
147int netlink_sendskb(struct sock *sk, struct sk_buff *skb);
148
149static inline struct sk_buff *
150netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
151{
152 struct sk_buff *nskb;
153
154 nskb = skb_clone(skb, gfp_mask);
155 if (!nskb)
156 return NULL;
157
158 /* This is a large skb, set destructor callback to release head */
159 if (is_vmalloc_addr(skb->head))
160 nskb->destructor = skb->destructor;
161
162 return nskb;
163}
164
165/*
166 * skb should fit one page. This choice is good for headerless malloc.
167 * But we should limit to 8K so that userspace does not have to
168 * use enormous buffer sizes on recvmsg() calls just to avoid
169 * MSG_TRUNC when PAGE_SIZE is very large.
170 */
171#if PAGE_SIZE < 8192UL
172#define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(PAGE_SIZE)
173#else
174#define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(8192UL)
175#endif
176
177#define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)
178
179
180struct netlink_callback {
181 struct sk_buff *skb;
182 const struct nlmsghdr *nlh;
183 int (*dump)(struct sk_buff * skb,
184 struct netlink_callback *cb);
185 int (*done)(struct netlink_callback *cb);
186 void *data;
187 /* the module that dump function belong to */
188 struct module *module;
189 struct netlink_ext_ack *extack;
190 u16 family;
191 u16 min_dump_alloc;
192 bool strict_check;
193 u16 answer_flags;
194 unsigned int prev_seq, seq;
195 long args[6];
196};
197
198struct netlink_notify {
199 struct net *net;
200 u32 portid;
201 int protocol;
202};
203
204struct nlmsghdr *
205__nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);
206
207struct netlink_dump_control {
208 int (*start)(struct netlink_callback *);
209 int (*dump)(struct sk_buff *skb, struct netlink_callback *);
210 int (*done)(struct netlink_callback *);
211 void *data;
212 struct module *module;
213 u16 min_dump_alloc;
214};
215
216int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
217 const struct nlmsghdr *nlh,
218 struct netlink_dump_control *control);
219static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
220 const struct nlmsghdr *nlh,
221 struct netlink_dump_control *control)
222{
223 if (!control->module)
224 control->module = THIS_MODULE;
225
226 return __netlink_dump_start(ssk, skb, nlh, control);
227}
228
229struct netlink_tap {
230 struct net_device *dev;
231 struct module *module;
232 struct list_head list;
233};
234
235int netlink_add_tap(struct netlink_tap *nt);
236int netlink_remove_tap(struct netlink_tap *nt);
237
238bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
239 struct user_namespace *ns, int cap);
240bool netlink_ns_capable(const struct sk_buff *skb,
241 struct user_namespace *ns, int cap);
242bool netlink_capable(const struct sk_buff *skb, int cap);
243bool netlink_net_capable(const struct sk_buff *skb, int cap);
244
245#endif /* __LINUX_NETLINK_H */
246