linux/net/sysctl_net.c
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   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_uid())) {
  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 (gid_eq(root_gid, current_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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