Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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#define NETLINK_CTX_SIZE 48
38
39
40void netlink_table_grab(void);
41void netlink_table_ungrab(void);
42
43#define NL_CFG_F_NONROOT_RECV (1 << 0)
44#define NL_CFG_F_NONROOT_SEND (1 << 1)
45
46/* optional Netlink kernel configuration parameters */
47struct netlink_kernel_cfg {
48 unsigned int groups;
49 unsigned int flags;
50 void (*input)(struct sk_buff *skb);
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 8
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 BUILD_BUG_ON(sizeof(extack->cookie) < sizeof(cookie));
216 memcpy(extack->cookie, &cookie, sizeof(cookie));
217 extack->cookie_len = sizeof(cookie);
218}
219
220void netlink_kernel_release(struct sock *sk);
221int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
222int netlink_change_ngroups(struct sock *sk, unsigned int groups);
223void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
224void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
225 const struct netlink_ext_ack *extack);
226int netlink_has_listeners(struct sock *sk, unsigned int group);
227bool netlink_strict_get_check(struct sk_buff *skb);
228
229int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
230int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
231 __u32 group, gfp_t allocation);
232
233typedef int (*netlink_filter_fn)(struct sock *dsk, struct sk_buff *skb, void *data);
234
235int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
236 __u32 portid, __u32 group, gfp_t allocation,
237 netlink_filter_fn filter,
238 void *filter_data);
239int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
240int netlink_register_notifier(struct notifier_block *nb);
241int netlink_unregister_notifier(struct notifier_block *nb);
242
243/* finegrained unicast helpers: */
244struct sock *netlink_getsockbyfd(int fd);
245int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
246 long *timeo, struct sock *ssk);
247void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
248int netlink_sendskb(struct sock *sk, struct sk_buff *skb);
249
250static inline struct sk_buff *
251netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
252{
253 struct sk_buff *nskb;
254
255 nskb = skb_clone(skb, gfp_mask);
256 if (!nskb)
257 return NULL;
258
259 /* This is a large skb, set destructor callback to release head */
260 if (is_vmalloc_addr(skb->head))
261 nskb->destructor = skb->destructor;
262
263 return nskb;
264}
265
266/*
267 * skb should fit one page. This choice is good for headerless malloc.
268 * But we should limit to 8K so that userspace does not have to
269 * use enormous buffer sizes on recvmsg() calls just to avoid
270 * MSG_TRUNC when PAGE_SIZE is very large.
271 */
272#if PAGE_SIZE < 8192UL
273#define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(PAGE_SIZE)
274#else
275#define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(8192UL)
276#endif
277
278#define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)
279
280
281struct netlink_callback {
282 struct sk_buff *skb;
283 const struct nlmsghdr *nlh;
284 int (*dump)(struct sk_buff * skb,
285 struct netlink_callback *cb);
286 int (*done)(struct netlink_callback *cb);
287 void *data;
288 /* the module that dump function belong to */
289 struct module *module;
290 struct netlink_ext_ack *extack;
291 u16 family;
292 u16 answer_flags;
293 u32 min_dump_alloc;
294 unsigned int prev_seq, seq;
295 int flags;
296 bool strict_check;
297 union {
298 u8 ctx[NETLINK_CTX_SIZE];
299
300 /* args is deprecated. Cast a struct over ctx instead
301 * for proper type safety.
302 */
303 long args[6];
304 };
305};
306
307#define NL_ASSERT_CTX_FITS(type_name) \
308 BUILD_BUG_ON(sizeof(type_name) > \
309 sizeof_field(struct netlink_callback, ctx))
310
311struct netlink_notify {
312 struct net *net;
313 u32 portid;
314 int protocol;
315};
316
317struct nlmsghdr *
318__nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);
319
320struct netlink_dump_control {
321 int (*start)(struct netlink_callback *);
322 int (*dump)(struct sk_buff *skb, struct netlink_callback *);
323 int (*done)(struct netlink_callback *);
324 struct netlink_ext_ack *extack;
325 void *data;
326 struct module *module;
327 u32 min_dump_alloc;
328 int flags;
329};
330
331int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
332 const struct nlmsghdr *nlh,
333 struct netlink_dump_control *control);
334static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
335 const struct nlmsghdr *nlh,
336 struct netlink_dump_control *control)
337{
338 if (!control->module)
339 control->module = THIS_MODULE;
340
341 return __netlink_dump_start(ssk, skb, nlh, control);
342}
343
344struct netlink_tap {
345 struct net_device *dev;
346 struct module *module;
347 struct list_head list;
348};
349
350int netlink_add_tap(struct netlink_tap *nt);
351int netlink_remove_tap(struct netlink_tap *nt);
352
353bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
354 struct user_namespace *ns, int cap);
355bool netlink_ns_capable(const struct sk_buff *skb,
356 struct user_namespace *ns, int cap);
357bool netlink_capable(const struct sk_buff *skb, int cap);
358bool netlink_net_capable(const struct sk_buff *skb, int cap);
359struct sk_buff *netlink_alloc_large_skb(unsigned int size, int broadcast);
360
361#endif /* __LINUX_NETLINK_H */