Line data Source code
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 :
16 277 : static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb)
17 : {
18 277 : 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 *
60 5 : netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg)
61 : {
62 5 : 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 :
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 : * @cookie: cookie data to return to userspace (for success)
75 : * @cookie_len: actual cookie data length
76 : */
77 : struct netlink_ext_ack {
78 : const char *_msg;
79 : const struct nlattr *bad_attr;
80 : const struct nla_policy *policy;
81 : u8 cookie[NETLINK_MAX_COOKIE_LEN];
82 : u8 cookie_len;
83 : };
84 :
85 : /* Always use this macro, this allows later putting the
86 : * message into a separate section or such for things
87 : * like translation or listing all possible messages.
88 : * Currently string formatting is not supported (due
89 : * to the lack of an output buffer.)
90 : */
91 : #define NL_SET_ERR_MSG(extack, msg) do { \
92 : static const char __msg[] = msg; \
93 : struct netlink_ext_ack *__extack = (extack); \
94 : \
95 : do_trace_netlink_extack(__msg); \
96 : \
97 : if (__extack) \
98 : __extack->_msg = __msg; \
99 : } while (0)
100 :
101 : #define NL_SET_ERR_MSG_MOD(extack, msg) \
102 : NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)
103 :
104 : #define NL_SET_BAD_ATTR_POLICY(extack, attr, pol) do { \
105 : if ((extack)) { \
106 : (extack)->bad_attr = (attr); \
107 : (extack)->policy = (pol); \
108 : } \
109 : } while (0)
110 :
111 : #define NL_SET_BAD_ATTR(extack, attr) NL_SET_BAD_ATTR_POLICY(extack, attr, NULL)
112 :
113 : #define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) do { \
114 : static const char __msg[] = msg; \
115 : struct netlink_ext_ack *__extack = (extack); \
116 : \
117 : do_trace_netlink_extack(__msg); \
118 : \
119 : if (__extack) { \
120 : __extack->_msg = __msg; \
121 : __extack->bad_attr = (attr); \
122 : __extack->policy = (pol); \
123 : } \
124 : } while (0)
125 :
126 : #define NL_SET_ERR_MSG_ATTR(extack, attr, msg) \
127 : NL_SET_ERR_MSG_ATTR_POL(extack, attr, NULL, msg)
128 :
129 : static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack,
130 : u64 cookie)
131 : {
132 : u64 __cookie = cookie;
133 :
134 : if (!extack)
135 : return;
136 : memcpy(extack->cookie, &__cookie, sizeof(__cookie));
137 : extack->cookie_len = sizeof(__cookie);
138 : }
139 :
140 : static inline void nl_set_extack_cookie_u32(struct netlink_ext_ack *extack,
141 : u32 cookie)
142 : {
143 : u32 __cookie = cookie;
144 :
145 : if (!extack)
146 : return;
147 : memcpy(extack->cookie, &__cookie, sizeof(__cookie));
148 : extack->cookie_len = sizeof(__cookie);
149 : }
150 :
151 : void netlink_kernel_release(struct sock *sk);
152 : int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
153 : int netlink_change_ngroups(struct sock *sk, unsigned int groups);
154 : void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
155 : void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
156 : const struct netlink_ext_ack *extack);
157 : int netlink_has_listeners(struct sock *sk, unsigned int group);
158 : bool netlink_strict_get_check(struct sk_buff *skb);
159 :
160 : int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
161 : int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
162 : __u32 group, gfp_t allocation);
163 : int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
164 : __u32 portid, __u32 group, gfp_t allocation,
165 : int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
166 : void *filter_data);
167 : int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
168 : int netlink_register_notifier(struct notifier_block *nb);
169 : int netlink_unregister_notifier(struct notifier_block *nb);
170 :
171 : /* finegrained unicast helpers: */
172 : struct sock *netlink_getsockbyfilp(struct file *filp);
173 : int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
174 : long *timeo, struct sock *ssk);
175 : void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
176 : int netlink_sendskb(struct sock *sk, struct sk_buff *skb);
177 :
178 : static inline struct sk_buff *
179 0 : netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
180 : {
181 0 : struct sk_buff *nskb;
182 :
183 0 : nskb = skb_clone(skb, gfp_mask);
184 0 : if (!nskb)
185 : return NULL;
186 :
187 : /* This is a large skb, set destructor callback to release head */
188 0 : if (is_vmalloc_addr(skb->head))
189 0 : nskb->destructor = skb->destructor;
190 :
191 : return nskb;
192 : }
193 :
194 : /*
195 : * skb should fit one page. This choice is good for headerless malloc.
196 : * But we should limit to 8K so that userspace does not have to
197 : * use enormous buffer sizes on recvmsg() calls just to avoid
198 : * MSG_TRUNC when PAGE_SIZE is very large.
199 : */
200 : #if PAGE_SIZE < 8192UL
201 : #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(PAGE_SIZE)
202 : #else
203 : #define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(8192UL)
204 : #endif
205 :
206 : #define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)
207 :
208 :
209 : struct netlink_callback {
210 : struct sk_buff *skb;
211 : const struct nlmsghdr *nlh;
212 : int (*dump)(struct sk_buff * skb,
213 : struct netlink_callback *cb);
214 : int (*done)(struct netlink_callback *cb);
215 : void *data;
216 : /* the module that dump function belong to */
217 : struct module *module;
218 : struct netlink_ext_ack *extack;
219 : u16 family;
220 : u16 answer_flags;
221 : u32 min_dump_alloc;
222 : unsigned int prev_seq, seq;
223 : bool strict_check;
224 : union {
225 : u8 ctx[48];
226 :
227 : /* args is deprecated. Cast a struct over ctx instead
228 : * for proper type safety.
229 : */
230 : long args[6];
231 : };
232 : };
233 :
234 : struct netlink_notify {
235 : struct net *net;
236 : u32 portid;
237 : int protocol;
238 : };
239 :
240 : struct nlmsghdr *
241 : __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);
242 :
243 : struct netlink_dump_control {
244 : int (*start)(struct netlink_callback *);
245 : int (*dump)(struct sk_buff *skb, struct netlink_callback *);
246 : int (*done)(struct netlink_callback *);
247 : void *data;
248 : struct module *module;
249 : u32 min_dump_alloc;
250 : };
251 :
252 : int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
253 : const struct nlmsghdr *nlh,
254 : struct netlink_dump_control *control);
255 33 : static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
256 : const struct nlmsghdr *nlh,
257 : struct netlink_dump_control *control)
258 : {
259 33 : if (!control->module)
260 33 : control->module = THIS_MODULE;
261 :
262 33 : return __netlink_dump_start(ssk, skb, nlh, control);
263 : }
264 :
265 : struct netlink_tap {
266 : struct net_device *dev;
267 : struct module *module;
268 : struct list_head list;
269 : };
270 :
271 : int netlink_add_tap(struct netlink_tap *nt);
272 : int netlink_remove_tap(struct netlink_tap *nt);
273 :
274 : bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
275 : struct user_namespace *ns, int cap);
276 : bool netlink_ns_capable(const struct sk_buff *skb,
277 : struct user_namespace *ns, int cap);
278 : bool netlink_capable(const struct sk_buff *skb, int cap);
279 : bool netlink_net_capable(const struct sk_buff *skb, int cap);
280 :
281 : #endif /* __LINUX_NETLINK_H */
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