Root/net/sysctl_net.c

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
29static struct ctl_table_set *
30net_ctl_header_lookup(struct ctl_table_root *root, struct nsproxy *namespaces)
31{
32    return &namespaces->net_ns->sysctls;
33}
34
35static 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. */
41static 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    kuid_t root_uid = make_kuid(net->user_ns, 0);
46    kgid_t root_gid = make_kgid(net->user_ns, 0);
47
48    /* Allow network administrator to have same access as root. */
49    if (ns_capable(net->user_ns, CAP_NET_ADMIN) ||
50        uid_eq(root_uid, current_euid())) {
51        int mode = (table->mode >> 6) & 7;
52        return (mode << 6) | (mode << 3) | mode;
53    }
54    /* Allow netns root group to have the same access as the root group */
55    if (in_egroup_p(root_gid)) {
56        int mode = (table->mode >> 3) & 7;
57        return (mode << 3) | mode;
58    }
59    return table->mode;
60}
61
62static struct ctl_table_root net_sysctl_root = {
63    .lookup = net_ctl_header_lookup,
64    .permissions = net_ctl_permissions,
65};
66
67static int __net_init sysctl_net_init(struct net *net)
68{
69    setup_sysctl_set(&net->sysctls, &net_sysctl_root, is_seen);
70    return 0;
71}
72
73static void __net_exit sysctl_net_exit(struct net *net)
74{
75    retire_sysctl_set(&net->sysctls);
76}
77
78static struct pernet_operations sysctl_pernet_ops = {
79    .init = sysctl_net_init,
80    .exit = sysctl_net_exit,
81};
82
83static struct ctl_table_header *net_header;
84__init int net_sysctl_init(void)
85{
86    static struct ctl_table empty[1];
87    int ret = -ENOMEM;
88    /* Avoid limitations in the sysctl implementation by
89     * registering "/proc/sys/net" as an empty directory not in a
90     * network namespace.
91     */
92    net_header = register_sysctl("net", empty);
93    if (!net_header)
94        goto out;
95    ret = register_pernet_subsys(&sysctl_pernet_ops);
96    if (ret)
97        goto out;
98    register_sysctl_root(&net_sysctl_root);
99out:
100    return ret;
101}
102
103struct ctl_table_header *register_net_sysctl(struct net *net,
104    const char *path, struct ctl_table *table)
105{
106    return __register_sysctl_table(&net->sysctls, path, table);
107}
108EXPORT_SYMBOL_GPL(register_net_sysctl);
109
110void unregister_net_sysctl_table(struct ctl_table_header *header)
111{
112    unregister_sysctl_table(header);
113}
114EXPORT_SYMBOL_GPL(unregister_net_sysctl_table);
115

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