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 #include <linux/skbuff.h>
  16 #include <linux/module.h>
  17 #include <linux/netfilter/x_tables.h>
  18 #include <linux/netfilter/xt_cgroup.h>
  19 #include <net/sock.h>
  20
  21 MODULE_LICENSE("GPL");
  22 MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
  23 MODULE_DESCRIPTION("Xtables: process control group matching");
  24 MODULE_ALIAS("ipt_cgroup");
  25 MODULE_ALIAS("ip6t_cgroup");
  26
  27 static int cgroup_mt_check_v0(const struct xt_mtchk_param *par)
  28 {
  29         struct xt_cgroup_info_v0 *info = par->matchinfo;
  30
  31         if (info->invert & ~1)
  32                 return -EINVAL;
  33
  34         return 0;
  35 }
  36
  37 static int cgroup_mt_check_v1(const struct xt_mtchk_param *par)
  38 {
  39         struct xt_cgroup_info_v1 *info = par->matchinfo;
  40         struct cgroup *cgrp;
  41
  42         if ((info->invert_path & ~1) || (info->invert_classid & ~1))
  43                 return -EINVAL;
  44
  45         if (!info->has_path && !info->has_classid) {
  46                 pr_info("xt_cgroup: no path or classid specified\n");
  47                 return -EINVAL;
  48         }
  49
  50         if (info->has_path && info->has_classid) {
  51                 pr_info("xt_cgroup: both path and classid specified\n");
  52                 return -EINVAL;
  53         }
  54
  55         info->priv = NULL;
  56         if (info->has_path) {
  57                 cgrp = cgroup_get_from_path(info->path);
  58                 if (IS_ERR(cgrp)) {
  59                         pr_info("xt_cgroup: invalid path, errno=%ld\n",
  60                                 PTR_ERR(cgrp));
  61                         return -EINVAL;
  62                 }
  63                 info->priv = cgrp;
  64         }
  65
  66         return 0;
  67 }
  68
  69 static bool
  70 cgroup_mt_v0(const struct sk_buff *skb, struct xt_action_param *par)
  71 {
  72         const struct xt_cgroup_info_v0 *info = par->matchinfo;
  73
  74         if (skb->sk == NULL || !sk_fullsock(skb->sk))
  75                 return false;
  76
  77         return (info->id == sock_cgroup_classid(&skb->sk->sk_cgrp_data)) ^
  78                 info->invert;
  79 }
  80
  81 static bool cgroup_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
  82 {
  83         const struct xt_cgroup_info_v1 *info = par->matchinfo;
  84         struct sock_cgroup_data *skcd = &skb->sk->sk_cgrp_data;
  85         struct cgroup *ancestor = info->priv;
  86
  87         if (!skb->sk || !sk_fullsock(skb->sk))
  88                 return false;
  89
  90         if (ancestor)
  91                 return cgroup_is_descendant(sock_cgroup_ptr(skcd), ancestor) ^
  92                         info->invert_path;
  93         else
  94                 return (info->classid == sock_cgroup_classid(skcd)) ^
  95                         info->invert_classid;
  96 }
  97
  98 static void cgroup_mt_destroy_v1(const struct xt_mtdtor_param *par)
  99 {
 100         struct xt_cgroup_info_v1 *info = par->matchinfo;
 101
 102         if (info->priv)
 103                 cgroup_put(info->priv);
 104 }
 105
 106 static struct xt_match cgroup_mt_reg[] __read_mostly = {
 107         {
 108                 .name           = "cgroup",
 109                 .revision       = 0,
 110                 .family         = NFPROTO_UNSPEC,
 111                 .checkentry     = cgroup_mt_check_v0,
 112                 .match          = cgroup_mt_v0,
 113                 .matchsize      = sizeof(struct xt_cgroup_info_v0),
 114                 .me             = THIS_MODULE,
 115                 .hooks          = (1 << NF_INET_LOCAL_OUT) |
 116                                   (1 << NF_INET_POST_ROUTING) |
 117                                   (1 << NF_INET_LOCAL_IN),
 118         },
 119         {
 120                 .name           = "cgroup",
 121                 .revision       = 1,
 122                 .family         = NFPROTO_UNSPEC,
 123                 .checkentry     = cgroup_mt_check_v1,
 124                 .match          = cgroup_mt_v1,
 125                 .matchsize      = sizeof(struct xt_cgroup_info_v1),
 126                 .usersize       = offsetof(struct xt_cgroup_info_v1, priv),
 127                 .destroy        = cgroup_mt_destroy_v1,
 128                 .me             = THIS_MODULE,
 129                 .hooks          = (1 << NF_INET_LOCAL_OUT) |
 130                                   (1 << NF_INET_POST_ROUTING) |
 131                                   (1 << NF_INET_LOCAL_IN),
 132         },
 133 };
 134
 135 static int __init cgroup_mt_init(void)
 136 {
 137         return xt_register_matches(cgroup_mt_reg, ARRAY_SIZE(cgroup_mt_reg));
 138 }
 139
 140 static void __exit cgroup_mt_exit(void)
 141 {
 142         xt_unregister_matches(cgroup_mt_reg, ARRAY_SIZE(cgroup_mt_reg));
 143 }
 144
 145 module_init(cgroup_mt_init);
 146 module_exit(cgroup_mt_exit);