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	void            (*release) (struct sock *sk, unsigned long *groups);
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#define NETLINK_MAX_FMTMSG_LEN	80
68
69/**
70 * struct netlink_ext_ack - netlink extended ACK report struct
71 * @_msg: message string to report - don't access directly, use
72 *	%NL_SET_ERR_MSG
73 * @bad_attr: attribute with error
74 * @policy: policy for a bad attribute
75 * @miss_type: attribute type which was missing
76 * @miss_nest: nest missing an attribute (%NULL if missing top level attr)
77 * @cookie: cookie data to return to userspace (for success)
78 * @cookie_len: actual cookie data length
79 * @_msg_buf: output buffer for formatted message strings - don't access
80 *	directly, use %NL_SET_ERR_MSG_FMT
81 */
82struct netlink_ext_ack {
83	const char *_msg;
84	const struct nlattr *bad_attr;
85	const struct nla_policy *policy;
86	const struct nlattr *miss_nest;
87	u16 miss_type;
88	u8 cookie[NETLINK_MAX_COOKIE_LEN];
89	u8 cookie_len;
90	char _msg_buf[NETLINK_MAX_FMTMSG_LEN];
91};
92
93/* Always use this macro, this allows later putting the
94 * message into a separate section or such for things
95 * like translation or listing all possible messages.
96 * If string formatting is needed use NL_SET_ERR_MSG_FMT.
97 */
98#define NL_SET_ERR_MSG(extack, msg) do {		\
99	static const char __msg[] = msg;		\
100	struct netlink_ext_ack *__extack = (extack);	\
101							\
102	do_trace_netlink_extack(__msg);			\
103							\
104	if (__extack)					\
105		__extack->_msg = __msg;			\
106} while (0)
107
108/* We splice fmt with %s at each end even in the snprintf so that both calls
109 * can use the same string constant, avoiding its duplication in .ro
110 */
111#define NL_SET_ERR_MSG_FMT(extack, fmt, args...) do {			       \
112	struct netlink_ext_ack *__extack = (extack);			       \
113									       \
114	if (!__extack)							       \
115		break;							       \
116	if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN,	       \
117		     "%s" fmt "%s", "", ##args, "") >=			       \
118	    NETLINK_MAX_FMTMSG_LEN)					       \
119		net_warn_ratelimited("%s" fmt "%s", "truncated extack: ",      \
120				     ##args, "\n");			       \
121									       \
122	do_trace_netlink_extack(__extack->_msg_buf);			       \
123									       \
124	__extack->_msg = __extack->_msg_buf;				       \
125} while (0)
126
127#define NL_SET_ERR_MSG_MOD(extack, msg)			\
128	NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)
129
130#define NL_SET_ERR_MSG_FMT_MOD(extack, fmt, args...)	\
131	NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args)
132
133#define NL_SET_ERR_MSG_WEAK(extack, msg) do {		\
134	if ((extack) && !(extack)->_msg)		\
135		NL_SET_ERR_MSG((extack), msg);		\
136} while (0)
137
138#define NL_SET_ERR_MSG_WEAK_MOD(extack, msg) do {	\
139	if ((extack) && !(extack)->_msg)		\
140		NL_SET_ERR_MSG_MOD((extack), msg);	\
141} while (0)
142
143#define NL_SET_BAD_ATTR_POLICY(extack, attr, pol) do {	\
144	if ((extack)) {					\
145		(extack)->bad_attr = (attr);		\
146		(extack)->policy = (pol);		\
147	}						\
148} while (0)
149
150#define NL_SET_BAD_ATTR(extack, attr) NL_SET_BAD_ATTR_POLICY(extack, attr, NULL)
151
152#define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) do {	\
153	static const char __msg[] = msg;			\
154	struct netlink_ext_ack *__extack = (extack);		\
155								\
156	do_trace_netlink_extack(__msg);				\
157								\
158	if (__extack) {						\
159		__extack->_msg = __msg;				\
160		__extack->bad_attr = (attr);			\
161		__extack->policy = (pol);			\
162	}							\
163} while (0)
164
165#define NL_SET_ERR_MSG_ATTR_POL_FMT(extack, attr, pol, fmt, args...) do {	\
166	struct netlink_ext_ack *__extack = (extack);				\
167										\
168	if (!__extack)								\
169		break;								\
170										\
171	if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN,		\
172		     "%s" fmt "%s", "", ##args, "") >=				\
173	    NETLINK_MAX_FMTMSG_LEN)						\
174		net_warn_ratelimited("%s" fmt "%s", "truncated extack: ",       \
175				     ##args, "\n");				\
176										\
177	do_trace_netlink_extack(__extack->_msg_buf);				\
178										\
179	__extack->_msg = __extack->_msg_buf;					\
180	__extack->bad_attr = (attr);						\
181	__extack->policy = (pol);						\
182} while (0)
183
184#define NL_SET_ERR_MSG_ATTR(extack, attr, msg)		\
185	NL_SET_ERR_MSG_ATTR_POL(extack, attr, NULL, msg)
186
187#define NL_SET_ERR_MSG_ATTR_FMT(extack, attr, msg, args...) \
188	NL_SET_ERR_MSG_ATTR_POL_FMT(extack, attr, NULL, msg, ##args)
189
190#define NL_SET_ERR_ATTR_MISS(extack, nest, type)  do {	\
191	struct netlink_ext_ack *__extack = (extack);	\
192							\
193	if (__extack) {					\
194		__extack->miss_nest = (nest);		\
195		__extack->miss_type = (type);		\
196	}						\
197} while (0)
198
199#define NL_REQ_ATTR_CHECK(extack, nest, tb, type) ({		\
200	struct nlattr **__tb = (tb);				\
201	u32 __attr = (type);					\
202	int __retval;						\
203								\
204	__retval = !__tb[__attr];				\
205	if (__retval)						\
206		NL_SET_ERR_ATTR_MISS((extack), (nest), __attr);	\
207	__retval;						\
208})
209
210static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack,
211					    u64 cookie)
212{
213	if (!extack)
214		return;
215	memcpy(extack->cookie, &cookie, sizeof(cookie));
216	extack->cookie_len = sizeof(cookie);
217}
218
219void netlink_kernel_release(struct sock *sk);
220int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
221int netlink_change_ngroups(struct sock *sk, unsigned int groups);
222void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
223void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
224		 const struct netlink_ext_ack *extack);
225int netlink_has_listeners(struct sock *sk, unsigned int group);
226bool netlink_strict_get_check(struct sk_buff *skb);
227
228int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
229int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
230		      __u32 group, gfp_t allocation);
231
232typedef int (*netlink_filter_fn)(struct sock *dsk, struct sk_buff *skb, void *data);
233
234int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
235			       __u32 portid, __u32 group, gfp_t allocation,
236			       netlink_filter_fn filter,
237			       void *filter_data);
238int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
239int netlink_register_notifier(struct notifier_block *nb);
240int netlink_unregister_notifier(struct notifier_block *nb);
241
242/* finegrained unicast helpers: */
243struct sock *netlink_getsockbyfilp(struct file *filp);
244int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
245		      long *timeo, struct sock *ssk);
246void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
247int netlink_sendskb(struct sock *sk, struct sk_buff *skb);
248
249static inline struct sk_buff *
250netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
251{
252	struct sk_buff *nskb;
253
254	nskb = skb_clone(skb, gfp_mask);
255	if (!nskb)
256		return NULL;
257
258	/* This is a large skb, set destructor callback to release head */
259	if (is_vmalloc_addr(skb->head))
260		nskb->destructor = skb->destructor;
261
262	return nskb;
263}
264
265/*
266 *	skb should fit one page. This choice is good for headerless malloc.
267 *	But we should limit to 8K so that userspace does not have to
268 *	use enormous buffer sizes on recvmsg() calls just to avoid
269 *	MSG_TRUNC when PAGE_SIZE is very large.
270 */
271#if PAGE_SIZE < 8192UL
272#define NLMSG_GOODSIZE	SKB_WITH_OVERHEAD(PAGE_SIZE)
273#else
274#define NLMSG_GOODSIZE	SKB_WITH_OVERHEAD(8192UL)
275#endif
276
277#define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)
278
279
280struct netlink_callback {
281	struct sk_buff		*skb;
282	const struct nlmsghdr	*nlh;
283	int			(*dump)(struct sk_buff * skb,
284					struct netlink_callback *cb);
285	int			(*done)(struct netlink_callback *cb);
286	void			*data;
287	/* the module that dump function belong to */
288	struct module		*module;
289	struct netlink_ext_ack	*extack;
290	u16			family;
291	u16			answer_flags;
292	u32			min_dump_alloc;
293	unsigned int		prev_seq, seq;
294	int			flags;
295	bool			strict_check;
296	union {
297		u8		ctx[48];
298
299		/* args is deprecated. Cast a struct over ctx instead
300		 * for proper type safety.
301		 */
302		long		args[6];
303	};
304};
305
306#define NL_ASSERT_DUMP_CTX_FITS(type_name)				\
307	BUILD_BUG_ON(sizeof(type_name) >				\
308		     sizeof_field(struct netlink_callback, ctx))
309
310struct netlink_notify {
311	struct net *net;
312	u32 portid;
313	int protocol;
314};
315
316struct nlmsghdr *
317__nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);
318
319struct netlink_dump_control {
320	int (*start)(struct netlink_callback *);
321	int (*dump)(struct sk_buff *skb, struct netlink_callback *);
322	int (*done)(struct netlink_callback *);
323	struct netlink_ext_ack *extack;
324	void *data;
325	struct module *module;
326	u32 min_dump_alloc;
327	int flags;
328};
329
330int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
331				const struct nlmsghdr *nlh,
332				struct netlink_dump_control *control);
333static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
334				     const struct nlmsghdr *nlh,
335				     struct netlink_dump_control *control)
336{
337	if (!control->module)
338		control->module = THIS_MODULE;
339
340	return __netlink_dump_start(ssk, skb, nlh, control);
341}
342
343struct netlink_tap {
344	struct net_device *dev;
345	struct module *module;
346	struct list_head list;
347};
348
349int netlink_add_tap(struct netlink_tap *nt);
350int netlink_remove_tap(struct netlink_tap *nt);
351
352bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
353			  struct user_namespace *ns, int cap);
354bool netlink_ns_capable(const struct sk_buff *skb,
355			struct user_namespace *ns, int cap);
356bool netlink_capable(const struct sk_buff *skb, int cap);
357bool netlink_net_capable(const struct sk_buff *skb, int cap);
358struct sk_buff *netlink_alloc_large_skb(unsigned int size, int broadcast);
359
360#endif	/* __LINUX_NETLINK_H */
361