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
12 struct net;
13
14 void do_trace_netlink_extack(const char *msg);
15
16 static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb)
17 {
18 return (struct nlmsghdr *)skb->data;
19 }
20
21 enum netlink_skb_flags {
22 NETLINK_SKB_DST = 0x8, /* Dst set in sendto or sendmsg */
23 };
24
25 struct 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
39 void netlink_table_grab(void);
40 void 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 */
46 struct netlink_kernel_cfg {
47 unsigned int groups;
48 unsigned int flags;
49 void (*input)(struct sk_buff *skb);
50 int (*bind)(struct net *net, int group);
51 void (*unbind)(struct net *net, int group);
52 void (*release) (struct sock *sk, unsigned long *groups);
53 };
54
55 struct sock *__netlink_kernel_create(struct net *net, int unit,
56 struct module *module,
57 struct netlink_kernel_cfg *cfg);
58 static inline struct sock *
59 netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg)
60 {
61 return __netlink_kernel_create(net, unit, THIS_MODULE, cfg);
62 }
63
64 /* this can be increased when necessary - don't expose to userland */
65 #define NETLINK_MAX_COOKIE_LEN 20
66 #define NETLINK_MAX_FMTMSG_LEN 80
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 * @miss_type: attribute type which was missing
75 * @miss_nest: nest missing an attribute (%NULL if missing top level attr)
76 * @cookie: cookie data to return to userspace (for success)
77 * @cookie_len: actual cookie data length
78 * @_msg_buf: output buffer for formatted message strings - don't access
79 * directly, use %NL_SET_ERR_MSG_FMT
80 */
81 struct netlink_ext_ack {
82 const char *_msg;
83 const struct nlattr *bad_attr;
84 const struct nla_policy *policy;
85 const struct nlattr *miss_nest;
86 u16 miss_type;
87 u8 cookie[NETLINK_MAX_COOKIE_LEN];
88 u8 cookie_len;
89 char _msg_buf[NETLINK_MAX_FMTMSG_LEN];
90 };
91
92 /* Always use this macro, this allows later putting the
93 * message into a separate section or such for things
94 * like translation or listing all possible messages.
95 * If string formatting is needed use NL_SET_ERR_MSG_FMT.
96 */
97 #define NL_SET_ERR_MSG(extack, msg) do { \
98 static const char __msg[] = msg; \
99 struct netlink_ext_ack *__extack = (extack); \
100 \
101 do_trace_netlink_extack(__msg); \
102 \
103 if (__extack) \
104 __extack->_msg = __msg; \
105 } while (0)
106
107 /* We splice fmt with %s at each end even in the snprintf so that both calls
108 * can use the same string constant, avoiding its duplication in .ro
109 */
110 #define NL_SET_ERR_MSG_FMT(extack, fmt, args...) do { \
111 struct netlink_ext_ack *__extack = (extack); \
112 \
113 if (!__extack) \
114 break; \
115 if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \
116 "%s" fmt "%s", "", ##args, "") >= \
117 NETLINK_MAX_FMTMSG_LEN) \
118 net_warn_ratelimited("%s" fmt "%s", "truncated extack: ", \
119 ##args, "\n"); \
120 \
121 do_trace_netlink_extack(__extack->_msg_buf); \
122 \
123 __extack->_msg = __extack->_msg_buf; \
124 } while (0)
125
126 #define NL_SET_ERR_MSG_MOD(extack, msg) \
127 NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)
128
129 #define NL_SET_ERR_MSG_FMT_MOD(extack, fmt, args...) \
130 NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args)
131
132 #define NL_SET_ERR_MSG_WEAK(extack, msg) do { \
133 if ((extack) && !(extack)->_msg) \
134 NL_SET_ERR_MSG((extack), msg); \
135 } while (0)
136
137 #define NL_SET_ERR_MSG_WEAK_MOD(extack, msg) do { \
138 if ((extack) && !(extack)->_msg) \
139 NL_SET_ERR_MSG_MOD((extack), msg); \
140 } while (0)
141
142 #define NL_SET_BAD_ATTR_POLICY(extack, attr, pol) do { \
143 if ((extack)) { \
144 (extack)->bad_attr = (attr); \
145 (extack)->policy = (pol); \
146 } \
147 } while (0)
148
149 #define NL_SET_BAD_ATTR(extack, attr) NL_SET_BAD_ATTR_POLICY(extack, attr, NULL)
150
151 #define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) do { \
152 static const char __msg[] = msg; \
153 struct netlink_ext_ack *__extack = (extack); \
154 \
155 do_trace_netlink_extack(__msg); \
156 \
157 if (__extack) { \
158 __extack->_msg = __msg; \
159 __extack->bad_attr = (attr); \
160 __extack->policy = (pol); \
161 } \
162 } while (0)
163
164 #define NL_SET_ERR_MSG_ATTR_POL_FMT(extack, attr, pol, fmt, args...) do { \
165 struct netlink_ext_ack *__extack = (extack); \
166 \
167 if (!__extack) \
168 break; \
169 \
170 if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \
171 "%s" fmt "%s", "", ##args, "") >= \
172 NETLINK_MAX_FMTMSG_LEN) \
173 net_warn_ratelimited("%s" fmt "%s", "truncated extack: ", \
174 ##args, "\n"); \
175 \
176 do_trace_netlink_extack(__extack->_msg_buf); \
177 \
178 __extack->_msg = __extack->_msg_buf; \
179 __extack->bad_attr = (attr); \
180 __extack->policy = (pol); \
181 } while (0)
182
183 #define NL_SET_ERR_MSG_ATTR(extack, attr, msg) \
184 NL_SET_ERR_MSG_ATTR_POL(extack, attr, NULL, msg)
185
186 #define NL_SET_ERR_MSG_ATTR_FMT(extack, attr, msg, args...) \
187 NL_SET_ERR_MSG_ATTR_POL_FMT(extack, attr, NULL, msg, ##args)
188
189 #define NL_SET_ERR_ATTR_MISS(extack, nest, type) do { \
190 struct netlink_ext_ack *__extack = (extack); \
191 \
192 if (__extack) { \
193 __extack->miss_nest = (nest); \
194 __extack->miss_type = (type); \
195 } \
196 } while (0)
197
198 #define NL_REQ_ATTR_CHECK(extack, nest, tb, type) ({ \
199 struct nlattr **__tb = (tb); \
200 u32 __attr = (type); \
201 int __retval; \
202 \
203 __retval = !__tb[__attr]; \
204 if (__retval) \
205 NL_SET_ERR_ATTR_MISS((extack), (nest), __attr); \
206 __retval; \
207 })
208
209 static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack,
210 u64 cookie)
211 {
212 if (!extack)
213 return;
214 memcpy(extack->cookie, &cookie, sizeof(cookie));
215 extack->cookie_len = sizeof(cookie);
216 }
217
218 void netlink_kernel_release(struct sock *sk);
219 int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
220 int netlink_change_ngroups(struct sock *sk, unsigned int groups);
221 void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
222 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
223 const struct netlink_ext_ack *extack);
224 int netlink_has_listeners(struct sock *sk, unsigned int group);
225 bool netlink_strict_get_check(struct sk_buff *skb);
226
227 int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
228 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
229 __u32 group, gfp_t allocation);
230
231 typedef int (*netlink_filter_fn)(struct sock *dsk, struct sk_buff *skb, void *data);
232
233 int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
234 __u32 portid, __u32 group, gfp_t allocation,
235 netlink_filter_fn filter,
236 void *filter_data);
237 int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
238 int netlink_register_notifier(struct notifier_block *nb);
239 int netlink_unregister_notifier(struct notifier_block *nb);
240
241 /* finegrained unicast helpers: */
242 struct sock *netlink_getsockbyfilp(struct file *filp);
243 int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
244 long *timeo, struct sock *ssk);
245 void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
246 int netlink_sendskb(struct sock *sk, struct sk_buff *skb);
247
248 static inline struct sk_buff *
249 netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
250 {
251 struct sk_buff *nskb;
252
253 nskb = skb_clone(skb, gfp_mask);
254 if (!nskb)
255 return NULL;
256
257 /* This is a large skb, set destructor callback to release head */
258 if (is_vmalloc_addr(skb->head))
259 nskb->destructor = skb->destructor;
260
261 return nskb;
262 }
263
264 /*
265 * skb should fit one page. This choice is good for headerless malloc.
266 * But we should limit to 8K so that userspace does not have to
267 * use enormous buffer sizes on recvmsg() calls just to avoid
268 * MSG_TRUNC when PAGE_SIZE is very large.
269 */
270 #if PAGE_SIZE < 8192UL
271 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(PAGE_SIZE)
272 #else
273 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(8192UL)
274 #endif
275
276 #define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)
277
278
279 struct netlink_callback {
280 struct sk_buff *skb;
281 const struct nlmsghdr *nlh;
282 int (*dump)(struct sk_buff * skb,
283 struct netlink_callback *cb);
284 int (*done)(struct netlink_callback *cb);
285 void *data;
286 /* the module that dump function belong to */
287 struct module *module;
288 struct netlink_ext_ack *extack;
289 u16 family;
290 u16 answer_flags;
291 u32 min_dump_alloc;
292 unsigned int prev_seq, seq;
293 int flags;
294 bool strict_check;
295 union {
296 u8 ctx[48];
297
298 /* args is deprecated. Cast a struct over ctx instead
299 * for proper type safety.
300 */
301 long args[6];
302 };
303 };
304
305 #define NL_ASSERT_DUMP_CTX_FITS(type_name) \
306 BUILD_BUG_ON(sizeof(type_name) > \
307 sizeof_field(struct netlink_callback, ctx))
308
309 struct netlink_notify {
310 struct net *net;
311 u32 portid;
312 int protocol;
313 };
314
315 struct nlmsghdr *
316 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);
317
318 struct netlink_dump_control {
319 int (*start)(struct netlink_callback *);
320 int (*dump)(struct sk_buff *skb, struct netlink_callback *);
321 int (*done)(struct netlink_callback *);
322 struct netlink_ext_ack *extack;
323 void *data;
324 struct module *module;
325 u32 min_dump_alloc;
326 int flags;
327 };
328
329 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
330 const struct nlmsghdr *nlh,
331 struct netlink_dump_control *control);
332 static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
333 const struct nlmsghdr *nlh,
334 struct netlink_dump_control *control)
335 {
336 if (!control->module)
337 control->module = THIS_MODULE;
338
339 return __netlink_dump_start(ssk, skb, nlh, control);
340 }
341
342 struct netlink_tap {
343 struct net_device *dev;
344 struct module *module;
345 struct list_head list;
346 };
347
348 int netlink_add_tap(struct netlink_tap *nt);
349 int netlink_remove_tap(struct netlink_tap *nt);
350
351 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
352 struct user_namespace *ns, int cap);
353 bool netlink_ns_capable(const struct sk_buff *skb,
354 struct user_namespace *ns, int cap);
355 bool netlink_capable(const struct sk_buff *skb, int cap);
356 bool netlink_net_capable(const struct sk_buff *skb, int cap);
357 struct sk_buff *netlink_alloc_large_skb(unsigned int size, int broadcast);
358
359 #endif /* __LINUX_NETLINK_H */
360
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