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 bool (*compare)(struct net *net, struct sock *sk);
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(extack, attr, msg) \
166 NL_SET_ERR_MSG_ATTR_POL(extack, attr, NULL, msg)
167
168 #define NL_SET_ERR_ATTR_MISS(extack, nest, type) do { \
169 struct netlink_ext_ack *__extack = (extack); \
170 \
171 if (__extack) { \
172 __extack->miss_nest = (nest); \
173 __extack->miss_type = (type); \
174 } \
175 } while (0)
176
177 #define NL_REQ_ATTR_CHECK(extack, nest, tb, type) ({ \
178 struct nlattr **__tb = (tb); \
179 u32 __attr = (type); \
180 int __retval; \
181 \
182 __retval = !__tb[__attr]; \
183 if (__retval) \
184 NL_SET_ERR_ATTR_MISS((extack), (nest), __attr); \
185 __retval; \
186 })
187
nl_set_extack_cookie_u64(struct netlink_ext_ack * extack,u64 cookie)188 static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack,
189 u64 cookie)
190 {
191 if (!extack)
192 return;
193 memcpy(extack->cookie, &cookie, sizeof(cookie));
194 extack->cookie_len = sizeof(cookie);
195 }
196
197 void netlink_kernel_release(struct sock *sk);
198 int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
199 int netlink_change_ngroups(struct sock *sk, unsigned int groups);
200 void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
201 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
202 const struct netlink_ext_ack *extack);
203 int netlink_has_listeners(struct sock *sk, unsigned int group);
204 bool netlink_strict_get_check(struct sk_buff *skb);
205
206 int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
207 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
208 __u32 group, gfp_t allocation);
209 int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
210 int netlink_register_notifier(struct notifier_block *nb);
211 int netlink_unregister_notifier(struct notifier_block *nb);
212
213 /* finegrained unicast helpers: */
214 struct sock *netlink_getsockbyfilp(struct file *filp);
215 int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
216 long *timeo, struct sock *ssk);
217 void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
218 int netlink_sendskb(struct sock *sk, struct sk_buff *skb);
219
220 static inline struct sk_buff *
netlink_skb_clone(struct sk_buff * skb,gfp_t gfp_mask)221 netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
222 {
223 struct sk_buff *nskb;
224
225 nskb = skb_clone(skb, gfp_mask);
226 if (!nskb)
227 return NULL;
228
229 /* This is a large skb, set destructor callback to release head */
230 if (is_vmalloc_addr(skb->head))
231 nskb->destructor = skb->destructor;
232
233 return nskb;
234 }
235
236 /*
237 * skb should fit one page. This choice is good for headerless malloc.
238 * But we should limit to 8K so that userspace does not have to
239 * use enormous buffer sizes on recvmsg() calls just to avoid
240 * MSG_TRUNC when PAGE_SIZE is very large.
241 */
242 #if PAGE_SIZE < 8192UL
243 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(PAGE_SIZE)
244 #else
245 #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(8192UL)
246 #endif
247
248 #define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)
249
250
251 struct netlink_callback {
252 struct sk_buff *skb;
253 const struct nlmsghdr *nlh;
254 int (*dump)(struct sk_buff * skb,
255 struct netlink_callback *cb);
256 int (*done)(struct netlink_callback *cb);
257 void *data;
258 /* the module that dump function belong to */
259 struct module *module;
260 struct netlink_ext_ack *extack;
261 u16 family;
262 u16 answer_flags;
263 u32 min_dump_alloc;
264 unsigned int prev_seq, seq;
265 bool strict_check;
266 union {
267 u8 ctx[48];
268
269 /* args is deprecated. Cast a struct over ctx instead
270 * for proper type safety.
271 */
272 long args[6];
273 };
274 };
275
276 #define NL_ASSERT_DUMP_CTX_FITS(type_name) \
277 BUILD_BUG_ON(sizeof(type_name) > \
278 sizeof_field(struct netlink_callback, ctx))
279
280 struct netlink_notify {
281 struct net *net;
282 u32 portid;
283 int protocol;
284 };
285
286 struct nlmsghdr *
287 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);
288
289 struct netlink_dump_control {
290 int (*start)(struct netlink_callback *);
291 int (*dump)(struct sk_buff *skb, struct netlink_callback *);
292 int (*done)(struct netlink_callback *);
293 void *data;
294 struct module *module;
295 u32 min_dump_alloc;
296 };
297
298 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
299 const struct nlmsghdr *nlh,
300 struct netlink_dump_control *control);
netlink_dump_start(struct sock * ssk,struct sk_buff * skb,const struct nlmsghdr * nlh,struct netlink_dump_control * control)301 static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
302 const struct nlmsghdr *nlh,
303 struct netlink_dump_control *control)
304 {
305 if (!control->module)
306 control->module = THIS_MODULE;
307
308 return __netlink_dump_start(ssk, skb, nlh, control);
309 }
310
311 struct netlink_tap {
312 struct net_device *dev;
313 struct module *module;
314 struct list_head list;
315 };
316
317 int netlink_add_tap(struct netlink_tap *nt);
318 int netlink_remove_tap(struct netlink_tap *nt);
319
320 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
321 struct user_namespace *ns, int cap);
322 bool netlink_ns_capable(const struct sk_buff *skb,
323 struct user_namespace *ns, int cap);
324 bool netlink_capable(const struct sk_buff *skb, int cap);
325 bool netlink_net_capable(const struct sk_buff *skb, int cap);
326
327 #endif /* __LINUX_NETLINK_H */
328