net/netfilter/xt_cgroup.c

   1 /*
   2  * Xtables module to match the process control group.
   3  *
   4  * Might be used to implement individual "per-application" firewall
   5  * policies in contrast to global policies based on control groups.
   6  * Matching is based upon processes tagged to net_cls' classid marker.
   7  *
   8  * (C) 2013 Daniel Borkmann <dborkman@redhat.com>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  */
  14
  15 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  16
  17 #include <linux/skbuff.h>
  18 #include <linux/module.h>
  19 #include <linux/netfilter/x_tables.h>
  20 #include <linux/netfilter/xt_cgroup.h>
  21 #include <net/sock.h>
  22
  23 MODULE_LICENSE("GPL");
  24 MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
  25 MODULE_DESCRIPTION("Xtables: process control group matching");
  26 MODULE_ALIAS("ipt_cgroup");
  27 MODULE_ALIAS("ip6t_cgroup");
  28
  29 static int cgroup_mt_check_v0(const struct xt_mtchk_param *par)
  30 {
  31         struct xt_cgroup_info_v0 *info = par->matchinfo;
  32
  33         if (info->invert & ~1)
  34                 return -EINVAL;
  35
  36         return 0;
  37 }
  38
  39 static int cgroup_mt_check_v1(const struct xt_mtchk_param *par)
  40 {
  41         struct xt_cgroup_info_v1 *info = par->matchinfo;
  42         struct cgroup *cgrp;
  43
  44         if ((info->invert_path & ~1) || (info->invert_classid & ~1))
  45                 return -EINVAL;
  46
  47         if (!info->has_path && !info->has_classid) {
  48                 pr_info("xt_cgroup: no path or classid specified\n");
  49                 return -EINVAL;
  50         }
  51
  52         if (info->has_path && info->has_classid) {
  53                 pr_info_ratelimited("path and classid specified\n");
  54                 return -EINVAL;
  55         }
  56
  57         info->priv = NULL;
  58         if (info->has_path) {
  59                 cgrp = cgroup_get_from_path(info->path);
  60                 if (IS_ERR(cgrp)) {
  61                         pr_info_ratelimited("invalid path, errno=%ld\n",
  62                                             PTR_ERR(cgrp));
  63                         return -EINVAL;
  64                 }
  65                 info->priv = cgrp;
  66         }
  67
  68         return 0;
  69 }
  70
  71 static bool
  72 cgroup_mt_v0(const struct sk_buff *skb, struct xt_action_param *par)
  73 {
  74         const struct xt_cgroup_info_v0 *info = par->matchinfo;
  75
  76         if (skb->sk == NULL || !sk_fullsock(skb->sk))
  77                 return false;
  78
  79         return (info->id == sock_cgroup_classid(&skb->sk->sk_cgrp_data)) ^
  80                 info->invert;
  81 }
  82
  83 static bool cgroup_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
  84 {
  85         const struct xt_cgroup_info_v1 *info = par->matchinfo;
  86         struct sock_cgroup_data *skcd = &skb->sk->sk_cgrp_data;
  87         struct cgroup *ancestor = info->priv;
  88
  89         if (!skb->sk || !sk_fullsock(skb->sk))
  90                 return false;
  91
  92         if (ancestor)
  93                 return cgroup_is_descendant(sock_cgroup_ptr(skcd), ancestor) ^
  94                         info->invert_path;
  95         else
  96                 return (info->classid == sock_cgroup_classid(skcd)) ^
  97                         info->invert_classid;
  98 }
  99
 100 static void cgroup_mt_destroy_v1(const struct xt_mtdtor_param *par)
 101 {
 102         struct xt_cgroup_info_v1 *info = par->matchinfo;
 103
 104         if (info->priv)
 105                 cgroup_put(info->priv);
 106 }
 107
 108 static struct xt_match cgroup_mt_reg[] __read_mostly = {
 109         {
 110                 .name           = "cgroup",
 111                 .revision       = 0,
 112                 .family         = NFPROTO_UNSPEC,
 113                 .checkentry     = cgroup_mt_check_v0,
 114                 .match          = cgroup_mt_v0,
 115                 .matchsize      = sizeof(struct xt_cgroup_info_v0),
 116                 .me             = THIS_MODULE,
 117                 .hooks          = (1 << NF_INET_LOCAL_OUT) |
 118                                   (1 << NF_INET_POST_ROUTING) |
 119                                   (1 << NF_INET_LOCAL_IN),
 120         },
 121         {
 122                 .name           = "cgroup",
 123                 .revision       = 1,
 124                 .family         = NFPROTO_UNSPEC,
 125                 .checkentry     = cgroup_mt_check_v1,
 126                 .match          = cgroup_mt_v1,
 127                 .matchsize      = sizeof(struct xt_cgroup_info_v1),
 128                 .usersize       = offsetof(struct xt_cgroup_info_v1, priv),
 129                 .destroy        = cgroup_mt_destroy_v1,
 130                 .me             = THIS_MODULE,
 131                 .hooks          = (1 << NF_INET_LOCAL_OUT) |
 132                                   (1 << NF_INET_POST_ROUTING) |
 133                                   (1 << NF_INET_LOCAL_IN),
 134         },
 135 };
 136
 137 static int __init cgroup_mt_init(void)
 138 {
 139         return xt_register_matches(cgroup_mt_reg, ARRAY_SIZE(cgroup_mt_reg));
 140 }
 141
 142 static void __exit cgroup_mt_exit(void)
 143 {
 144         xt_unregister_matches(cgroup_mt_reg, ARRAY_SIZE(cgroup_mt_reg));
 145 }
 146
 147 module_init(cgroup_mt_init);
 148 module_exit(cgroup_mt_exit);