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
nlmsg_hdr(const struct sk_buff * skb)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 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
56 struct sock *__netlink_kernel_create(struct net *net, int unit,
57 struct module *module,
58 struct netlink_kernel_cfg *cfg);
59 static inline struct sock *
netlink_kernel_create(struct net * net,int unit,struct netlink_kernel_cfg * cfg)60 netlink_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 */
82 struct 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
nl_set_extack_cookie_u64(struct netlink_ext_ack * extack,u64 cookie)210 static 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
219 void netlink_kernel_release(struct sock *sk);
220 int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
221 int netlink_change_ngroups(struct sock *sk, unsigned int groups);
222 void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
223 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
224 const struct netlink_ext_ack *extack);
225 int netlink_has_listeners(struct sock *sk, unsigned int group);
226 bool netlink_strict_get_check(struct sk_buff *skb);
227
228 int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
229 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
230 __u32 group, gfp_t allocation);
231
232 typedef int (*netlink_filter_fn)(struct sock *dsk, struct sk_buff *skb, void *data);
233
234 int 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);
238 int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
239 int netlink_register_notifier(struct notifier_block *nb);
240 int netlink_unregister_notifier(struct notifier_block *nb);
241
242 /* finegrained unicast helpers: */
243 struct sock *netlink_getsockbyfilp(struct file *filp);
244 int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
245 long *timeo, struct sock *ssk);
246 void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
247 int netlink_sendskb(struct sock *sk, struct sk_buff *skb);
248
249 static inline struct sk_buff *
netlink_skb_clone(struct sk_buff * skb,gfp_t gfp_mask)250 netlink_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
280 struct 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
310 struct netlink_notify {
311 struct net *net;
312 u32 portid;
313 int protocol;
314 };
315
316 struct nlmsghdr *
317 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);
318
319 struct 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
330 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
331 const struct nlmsghdr *nlh,
332 struct netlink_dump_control *control);
netlink_dump_start(struct sock * ssk,struct sk_buff * skb,const struct nlmsghdr * nlh,struct netlink_dump_control * control)333 static 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
343 struct netlink_tap {
344 struct net_device *dev;
345 struct module *module;
346 struct list_head list;
347 };
348
349 int netlink_add_tap(struct netlink_tap *nt);
350 int netlink_remove_tap(struct netlink_tap *nt);
351
352 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
353 struct user_namespace *ns, int cap);
354 bool netlink_ns_capable(const struct sk_buff *skb,
355 struct user_namespace *ns, int cap);
356 bool netlink_capable(const struct sk_buff *skb, int cap);
357 bool netlink_net_capable(const struct sk_buff *skb, int cap);
358 struct sk_buff *netlink_alloc_large_skb(unsigned int size, int broadcast);
359
360 #endif /* __LINUX_NETLINK_H */
361