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
  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         register_sysctl_root(&net_sysctl_root);
 110 out:
 111         return ret;
 112 out1:
 113         unregister_sysctl_table(net_header);
 114         net_header = NULL;
 115         goto out;
 116 }
 117
 118 struct 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 }
 123 EXPORT_SYMBOL_GPL(register_net_sysctl);
 124
 125 void unregister_net_sysctl_table(struct ctl_table_header *header)
 126 {
 127         unregister_sysctl_table(header);
 128 }
 129 EXPORT_SYMBOL_GPL(unregister_net_sysctl_table);