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, struct nsproxy *namespaces)
  31 {
  32         return &namespaces->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         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
  62 static struct ctl_table_root net_sysctl_root = {
  63         .lookup = net_ctl_header_lookup,
  64         .permissions = net_ctl_permissions,
  65 };
  66
  67 static 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
  73 static void __net_exit sysctl_net_exit(struct net *net)
  74 {
  75         retire_sysctl_set(&net->sysctls);
  76 }
  77
  78 static struct pernet_operations sysctl_pernet_ops = {
  79         .init = sysctl_net_init,
  80         .exit = sysctl_net_exit,
  81 };
  82
  83 static 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);
  99 out:
 100         return ret;
 101 }
 102
 103 struct 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 }
 108 EXPORT_SYMBOL_GPL(register_net_sysctl);
 109
 110 void unregister_net_sysctl_table(struct ctl_table_header *header)
 111 {
 112         unregister_sysctl_table(header);
 113 }
 114 EXPORT_SYMBOL_GPL(unregister_net_sysctl_table);