xref: /linux/net/sysctl_net.c (revision fd639726bf15fca8ee1a00dce8e0096d0ad9bd18) 
1 /* -*- linux-c -*-
2  * sysctl_net.c: sysctl interface to net subsystem.
3  *
4  * Begun April 1, 1996, Mike Shaver.
5  * Added /proc/sys/net directories for each protocol family. [MS]
6  *
7  * Revision 1.2  1996/05/08  20:24:40  shaver
8  * Added bits for NET_BRIDGE and the NET_IPV4_ARP stuff and
9  * NET_IPV4_IP_FORWARD.
10  *
11  *
12  */
13 
14 #include <linux/mm.h>
15 #include <linux/export.h>
16 #include <linux/sysctl.h>
17 #include <linux/nsproxy.h>
18 
19 #include <net/sock.h>
20 
21 #ifdef CONFIG_INET
22 #include <net/ip.h>
23 #endif
24 
25 #ifdef CONFIG_NET
26 #include <linux/if_ether.h>
27 #endif
28 
29 static struct ctl_table_set *
30 net_ctl_header_lookup(struct ctl_table_root *root)
31 {
32 	return &current->nsproxy->net_ns->sysctls;
33 }
34 
35 static int is_seen(struct ctl_table_set *set)
36 {
37 	return &current->nsproxy->net_ns->sysctls == set;
38 }
39 
40 /* Return standard mode bits for table entry. */
41 static int net_ctl_permissions(struct ctl_table_header *head,
42 			       struct ctl_table *table)
43 {
44 	struct net *net = container_of(head->set, struct net, sysctls);
45 
46 	/* Allow network administrator to have same access as root. */
47 	if (ns_capable_noaudit(net->user_ns, CAP_NET_ADMIN)) {
48 		int mode = (table->mode >> 6) & 7;
49 		return (mode << 6) | (mode << 3) | mode;
50 	}
51 
52 	return table->mode;
53 }
54 
55 static void net_ctl_set_ownership(struct ctl_table_header *head,
56 				  struct ctl_table *table,
57 				  kuid_t *uid, kgid_t *gid)
58 {
59 	struct net *net = container_of(head->set, struct net, sysctls);
60 	kuid_t ns_root_uid;
61 	kgid_t ns_root_gid;
62 
63 	ns_root_uid = make_kuid(net->user_ns, 0);
64 	if (uid_valid(ns_root_uid))
65 		*uid = ns_root_uid;
66 
67 	ns_root_gid = make_kgid(net->user_ns, 0);
68 	if (gid_valid(ns_root_gid))
69 		*gid = ns_root_gid;
70 }
71 
72 static struct ctl_table_root net_sysctl_root = {
73 	.lookup = net_ctl_header_lookup,
74 	.permissions = net_ctl_permissions,
75 	.set_ownership = net_ctl_set_ownership,
76 };
77 
78 static int __net_init sysctl_net_init(struct net *net)
79 {
80 	setup_sysctl_set(&net->sysctls, &net_sysctl_root, is_seen);
81 	return 0;
82 }
83 
84 static void __net_exit sysctl_net_exit(struct net *net)
85 {
86 	retire_sysctl_set(&net->sysctls);
87 }
88 
89 static struct pernet_operations sysctl_pernet_ops = {
90 	.init = sysctl_net_init,
91 	.exit = sysctl_net_exit,
92 };
93 
94 static struct ctl_table_header *net_header;
95 __init int net_sysctl_init(void)
96 {
97 	static struct ctl_table empty[1];
98 	int ret = -ENOMEM;
99 	/* Avoid limitations in the sysctl implementation by
100 	 * registering "/proc/sys/net" as an empty directory not in a
101 	 * network namespace.
102 	 */
103 	net_header = register_sysctl("net", empty);
104 	if (!net_header)
105 		goto out;
106 	ret = register_pernet_subsys(&sysctl_pernet_ops);
107 	if (ret)
108 		goto out1;
109 out:
110 	return ret;
111 out1:
112 	unregister_sysctl_table(net_header);
113 	net_header = NULL;
114 	goto out;
115 }
116 
117 struct ctl_table_header *register_net_sysctl(struct net *net,
118 	const char *path, struct ctl_table *table)
119 {
120 	return __register_sysctl_table(&net->sysctls, path, table);
121 }
122 EXPORT_SYMBOL_GPL(register_net_sysctl);
123 
124 void unregister_net_sysctl_table(struct ctl_table_header *header)
125 {
126 	unregister_sysctl_table(header);
127 }
128 EXPORT_SYMBOL_GPL(unregister_net_sysctl_table);
129