summaryrefslogtreecommitdiff
path: root/include/linux/netlink.h
blob: 19c0791ed9d56f1b6ffe5d1bde79b3332de77f51 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_NETLINK_H
#define __LINUX_NETLINK_H


#include <linux/capability.h>
#include <linux/skbuff.h>
#include <linux/export.h>
#include <net/scm.h>
#include <uapi/linux/netlink.h>

struct net;

void do_trace_netlink_extack(const char *msg);

static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb)
{
	return (struct nlmsghdr *)skb->data;
}

enum netlink_skb_flags {
	NETLINK_SKB_DST		= 0x8,	/* Dst set in sendto or sendmsg */
};

struct netlink_skb_parms {
	struct scm_creds	creds;		/* Skb credentials	*/
	__u32			portid;
	__u32			dst_group;
	__u32			flags;
	struct sock		*sk;
	bool			nsid_is_set;
	int			nsid;
};

#define NETLINK_CB(skb)		(*(struct netlink_skb_parms*)&((skb)->cb))
#define NETLINK_CREDS(skb)	(&NETLINK_CB((skb)).creds)


void netlink_table_grab(void);
void netlink_table_ungrab(void);

#define NL_CFG_F_NONROOT_RECV	(1 << 0)
#define NL_CFG_F_NONROOT_SEND	(1 << 1)

/* optional Netlink kernel configuration parameters */
struct netlink_kernel_cfg {
	unsigned int	groups;
	unsigned int	flags;
	void		(*input)(struct sk_buff *skb);
	struct mutex	*cb_mutex;
	int		(*bind)(struct net *net, int group);
	void		(*unbind)(struct net *net, int group);
};

struct sock *__netlink_kernel_create(struct net *net, int unit,
					    struct module *module,
					    struct netlink_kernel_cfg *cfg);
static inline struct sock *
netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg)
{
	return __netlink_kernel_create(net, unit, THIS_MODULE, cfg);
}

/* this can be increased when necessary - don't expose to userland */
#define NETLINK_MAX_COOKIE_LEN	20
#define NETLINK_MAX_FMTMSG_LEN	80

/**
 * struct netlink_ext_ack - netlink extended ACK report struct
 * @_msg: message string to report - don't access directly, use
 *	%NL_SET_ERR_MSG
 * @bad_attr: attribute with error
 * @policy: policy for a bad attribute
 * @miss_type: attribute type which was missing
 * @miss_nest: nest missing an attribute (%NULL if missing top level attr)
 * @cookie: cookie data to return to userspace (for success)
 * @cookie_len: actual cookie data length
 * @_msg_buf: output buffer for formatted message strings - don't access
 *	directly, use %NL_SET_ERR_MSG_FMT
 */
struct netlink_ext_ack {
	const char *_msg;
	const struct nlattr *bad_attr;
	const struct nla_policy *policy;
	const struct nlattr *miss_nest;
	u16 miss_type;
	u8 cookie[NETLINK_MAX_COOKIE_LEN];
	u8 cookie_len;
	char _msg_buf[NETLINK_MAX_FMTMSG_LEN];
};

/* Always use this macro, this allows later putting the
 * message into a separate section or such for things
 * like translation or listing all possible messages.
 * If string formatting is needed use NL_SET_ERR_MSG_FMT.
 */
#define NL_SET_ERR_MSG(extack, msg) do {		\
	static const char __msg[] = msg;		\
	struct netlink_ext_ack *__extack = (extack);	\
							\
	do_trace_netlink_extack(__msg);			\
							\
	if (__extack)					\
		__extack->_msg = __msg;			\
} while (0)

/* We splice fmt with %s at each end even in the snprintf so that both calls
 * can use the same string constant, avoiding its duplication in .ro
 */
#define NL_SET_ERR_MSG_FMT(extack, fmt, args...) do {			       \
	struct netlink_ext_ack *__extack = (extack);			       \
									       \
	if (!__extack)							       \
		break;							       \
	if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN,	       \
		     "%s" fmt "%s", "", ##args, "") >=			       \
	    NETLINK_MAX_FMTMSG_LEN)					       \
		net_warn_ratelimited("%s" fmt "%s", "truncated extack: ",      \
				     ##args, "\n");			       \
									       \
	do_trace_netlink_extack(__extack->_msg_buf);			       \
									       \
	__extack->_msg = __extack->_msg_buf;				       \
} while (0)

#define NL_SET_ERR_MSG_MOD(extack, msg)			\
	NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)

#define NL_SET_ERR_MSG_FMT_MOD(extack, fmt, args...)	\
	NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args)

#define NL_SET_ERR_MSG_WEAK(extack, msg) do {		\
	if ((extack) && !(extack)->_msg)		\
		NL_SET_ERR_MSG((extack), msg);		\
} while (0)

#define NL_SET_ERR_MSG_WEAK_MOD(extack, msg) do {	\
	if ((extack) && !(extack)->_msg)		\
		NL_SET_ERR_MSG_MOD((extack), msg);	\
} while (0)

#define NL_SET_BAD_ATTR_POLICY(extack, attr, pol) do {	\
	if ((extack)) {					\
		(extack)->bad_attr = (attr);		\
		(extack)->policy = (pol);		\
	}						\
} while (0)

#define NL_SET_BAD_ATTR(extack, attr) NL_SET_BAD_ATTR_POLICY(extack, attr, NULL)

#define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) do {	\
	static const char __msg[] = msg;			\
	struct netlink_ext_ack *__extack = (extack);		\
								\
	do_trace_netlink_extack(__msg);				\
								\
	if (__extack) {						\
		__extack->_msg = __msg;				\
		__extack->bad_attr = (attr);			\
		__extack->policy = (pol);			\
	}							\
} while (0)

#define NL_SET_ERR_MSG_ATTR_POL_FMT(extack, attr, pol, fmt, args...) do {	\
	struct netlink_ext_ack *__extack = (extack);				\
										\
	if (!__extack)								\
		break;								\
										\
	if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN,		\
		     "%s" fmt "%s", "", ##args, "") >=				\
	    NETLINK_MAX_FMTMSG_LEN)						\
		net_warn_ratelimited("%s" fmt "%s", "truncated extack: ",       \
				     ##args, "\n");				\
										\
	do_trace_netlink_extack(__extack->_msg_buf);				\
										\
	__extack->_msg = __extack->_msg_buf;					\
	__extack->bad_attr = (attr);						\
	__extack->policy = (pol);						\
} while (0)

#define NL_SET_ERR_MSG_ATTR(extack, attr, msg)		\
	NL_SET_ERR_MSG_ATTR_POL(extack, attr, NULL, msg)

#define NL_SET_ERR_MSG_ATTR_FMT(extack, attr, msg, args...) \
	NL_SET_ERR_MSG_ATTR_POL_FMT(extack, attr, NULL, msg, ##args)

#define NL_SET_ERR_ATTR_MISS(extack, nest, type)  do {	\
	struct netlink_ext_ack *__extack = (extack);	\
							\
	if (__extack) {					\
		__extack->miss_nest = (nest);		\
		__extack->miss_type = (type);		\
	}						\
} while (0)

#define NL_REQ_ATTR_CHECK(extack, nest, tb, type) ({		\
	struct nlattr **__tb = (tb);				\
	u32 __attr = (type);					\
	int __retval;						\
								\
	__retval = !__tb[__attr];				\
	if (__retval)						\
		NL_SET_ERR_ATTR_MISS((extack), (nest), __attr);	\
	__retval;						\
})

static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack,
					    u64 cookie)
{
	if (!extack)
		return;
	memcpy(extack->cookie, &cookie, sizeof(cookie));
	extack->cookie_len = sizeof(cookie);
}

void netlink_kernel_release(struct sock *sk);
int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
int netlink_change_ngroups(struct sock *sk, unsigned int groups);
void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
		 const struct netlink_ext_ack *extack);
int netlink_has_listeners(struct sock *sk, unsigned int group);
bool netlink_strict_get_check(struct sk_buff *skb);

int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
		      __u32 group, gfp_t allocation);
int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
int netlink_register_notifier(struct notifier_block *nb);
int netlink_unregister_notifier(struct notifier_block *nb);

/* finegrained unicast helpers: */
struct sock *netlink_getsockbyfilp(struct file *filp);
int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
		      long *timeo, struct sock *ssk);
void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
int netlink_sendskb(struct sock *sk, struct sk_buff *skb);

static inline struct sk_buff *
netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
{
	struct sk_buff *nskb;

	nskb = skb_clone(skb, gfp_mask);
	if (!nskb)
		return NULL;

	/* This is a large skb, set destructor callback to release head */
	if (is_vmalloc_addr(skb->head))
		nskb->destructor = skb->destructor;

	return nskb;
}

/*
 *	skb should fit one page. This choice is good for headerless malloc.
 *	But we should limit to 8K so that userspace does not have to
 *	use enormous buffer sizes on recvmsg() calls just to avoid
 *	MSG_TRUNC when PAGE_SIZE is very large.
 */
#if PAGE_SIZE < 8192UL
#define NLMSG_GOODSIZE	SKB_WITH_OVERHEAD(PAGE_SIZE)
#else
#define NLMSG_GOODSIZE	SKB_WITH_OVERHEAD(8192UL)
#endif

#define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)


struct netlink_callback {
	struct sk_buff		*skb;
	const struct nlmsghdr	*nlh;
	int			(*dump)(struct sk_buff * skb,
					struct netlink_callback *cb);
	int			(*done)(struct netlink_callback *cb);
	void			*data;
	/* the module that dump function belong to */
	struct module		*module;
	struct netlink_ext_ack	*extack;
	u16			family;
	u16			answer_flags;
	u32			min_dump_alloc;
	unsigned int		prev_seq, seq;
	bool			strict_check;
	union {
		u8		ctx[48];

		/* args is deprecated. Cast a struct over ctx instead
		 * for proper type safety.
		 */
		long		args[6];
	};
};

#define NL_ASSERT_DUMP_CTX_FITS(type_name)				\
	BUILD_BUG_ON(sizeof(type_name) >				\
		     sizeof_field(struct netlink_callback, ctx))

struct netlink_notify {
	struct net *net;
	u32 portid;
	int protocol;
};

struct nlmsghdr *
__nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);

struct netlink_dump_control {
	int (*start)(struct netlink_callback *);
	int (*dump)(struct sk_buff *skb, struct netlink_callback *);
	int (*done)(struct netlink_callback *);
	void *data;
	struct module *module;
	u32 min_dump_alloc;
};

int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
				const struct nlmsghdr *nlh,
				struct netlink_dump_control *control);
static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
				     const struct nlmsghdr *nlh,
				     struct netlink_dump_control *control)
{
	if (!control->module)
		control->module = THIS_MODULE;

	return __netlink_dump_start(ssk, skb, nlh, control);
}

struct netlink_tap {
	struct net_device *dev;
	struct module *module;
	struct list_head list;
};

int netlink_add_tap(struct netlink_tap *nt);
int netlink_remove_tap(struct netlink_tap *nt);

bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
			  struct user_namespace *ns, int cap);
bool netlink_ns_capable(const struct sk_buff *skb,
			struct user_namespace *ns, int cap);
bool netlink_capable(const struct sk_buff *skb, int cap);
bool netlink_net_capable(const struct sk_buff *skb, int cap);

#endif	/* __LINUX_NETLINK_H */