LXR linux/net/sysctl

   1// SPDX-License-Identifier: GPL-2.0-only
   2/* -*- linux-c -*-
   3 * sysctl_net.c: sysctl interface to net subsystem.
   4 *
   5 * Begun April 1, 1996, Mike Shaver.
   6 * Added /proc/sys/net directories for each protocol family. [MS]
   7 *
   8 * Revision 1.2  1996/05/08  20:24:40  shaver
   9 * Added bits for NET_BRIDGE and the NET_IPV4_ARP stuff and
  10 * NET_IPV4_IP_FORWARD.
  11 *
  12 *
  13 */
  14
  15#include <linux/mm.h>
  16#include <linux/export.h>
  17#include <linux/sysctl.h>
  18#include <linux/nsproxy.h>
  19
  20#include <net/sock.h>
  21
  22#ifdef CONFIG_INET
  23#include <net/ip.h>
  24#endif
  25
  26#ifdef CONFIG_NET
  27#include <linux/if_ether.h>
  28#endif
  29
  30static struct ctl_table_set *
  31net_ctl_header_lookup(struct ctl_table_root *root)
  32{
  33        return &current->nsproxy->net_ns->sysctls;
  34}
  35
  36static int is_seen(struct ctl_table_set *set)
  37{
  38        return &current->nsproxy->net_ns->sysctls == set;
  39}
  40
  41/* Return standard mode bits for table entry. */
  42static int net_ctl_permissions(struct ctl_table_header *head,
  43                               struct ctl_table *table)
  44{
  45        struct net *net = container_of(head->set, struct net, sysctls);
  46
  47        /* Allow network administrator to have same access as root. */
  48        if (ns_capable_noaudit(net->user_ns, CAP_NET_ADMIN)) {
  49                int mode = (table->mode >> 6) & 7;
  50                return (mode << 6) | (mode << 3) | mode;
  51        }
  52
  53        return table->mode;
  54}
  55
  56static void net_ctl_set_ownership(struct ctl_table_header *head,
  57                                  struct ctl_table *table,
  58                                  kuid_t *uid, kgid_t *gid)
  59{
  60        struct net *net = container_of(head->set, struct net, sysctls);
  61        kuid_t ns_root_uid;
  62        kgid_t ns_root_gid;
  63
  64        ns_root_uid = make_kuid(net->user_ns, 0);
  65        if (uid_valid(ns_root_uid))
  66                *uid = ns_root_uid;
  67
  68        ns_root_gid = make_kgid(net->user_ns, 0);
  69        if (gid_valid(ns_root_gid))
  70                *gid = ns_root_gid;
  71}
  72
  73static struct ctl_table_root net_sysctl_root = {
  74        .lookup = net_ctl_header_lookup,
  75        .permissions = net_ctl_permissions,
  76        .set_ownership = net_ctl_set_ownership,
  77};
  78
  79static int __net_init sysctl_net_init(struct net *net)
  80{
  81        setup_sysctl_set(&net->sysctls, &net_sysctl_root, is_seen);
  82        return 0;
  83}
  84
  85static void __net_exit sysctl_net_exit(struct net *net)
  86{
  87        retire_sysctl_set(&net->sysctls);
  88}
  89
  90static struct pernet_operations sysctl_pernet_ops = {
  91        .init = sysctl_net_init,
  92        .exit = sysctl_net_exit,
  93};
  94
  95static struct ctl_table_header *net_header;
  96__init int net_sysctl_init(void)
  97{
  98        static struct ctl_table empty[1];
  99        int ret = -ENOMEM;
 100        /* Avoid limitations in the sysctl implementation by
 101         * registering "/proc/sys/net" as an empty directory not in a
 102         * network namespace.
 103         */
 104        net_header = register_sysctl("net", empty);
 105        if (!net_header)
 106                goto out;
 107        ret = register_pernet_subsys(&sysctl_pernet_ops);
 108        if (ret)
 109                goto out1;
 110out:
 111        return ret;
 112out1:
 113        unregister_sysctl_table(net_header);
 114        net_header = NULL;
 115        goto out;
 116}
 117
 118struct ctl_table_header *register_net_sysctl(struct net *net,
 119        const char *path, struct ctl_table *table)
 120{
 121        return __register_sysctl_table(&net->sysctls, path, table);
 122}
 123EXPORT_SYMBOL_GPL(register_net_sysctl);
 124
 125void unregister_net_sysctl_table(struct ctl_table_header *header)
 126{
 127        unregister_sysctl_table(header);
 128}
 129EXPORT_SYMBOL_GPL(unregister_net_sysctl_table);
 130