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         struct sock *sk = skb->sk;
  76
  77         if (!sk || !sk_fullsock(sk) || !net_eq(xt_net(par), sock_net(sk)))
  78                 return false;
  79
  80         return (info->id == sock_cgroup_classid(&skb->sk->sk_cgrp_data)) ^
  81                 info->invert;
  82 }
  83
  84 static bool cgroup_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
  85 {
  86         const struct xt_cgroup_info_v1 *info = par->matchinfo;
  87         struct sock_cgroup_data *skcd = &skb->sk->sk_cgrp_data;
  88         struct cgroup *ancestor = info->priv;
  89         struct sock *sk = skb->sk;
  90
  91         if (!sk || !sk_fullsock(sk) || !net_eq(xt_net(par), sock_net(sk)))
  92                 return false;
  93
  94         if (ancestor)
  95                 return cgroup_is_descendant(sock_cgroup_ptr(skcd), ancestor) ^
  96                         info->invert_path;
  97         else
  98                 return (info->classid == sock_cgroup_classid(skcd)) ^
  99                         info->invert_classid;
 100 }
 101
 102 static void cgroup_mt_destroy_v1(const struct xt_mtdtor_param *par)
 103 {
 104         struct xt_cgroup_info_v1 *info = par->matchinfo;
 105
 106         if (info->priv)
 107                 cgroup_put(info->priv);
 108 }
 109
 110 static struct xt_match cgroup_mt_reg[] __read_mostly = {
 111         {
 112                 .name           = "cgroup",
 113                 .revision       = 0,
 114                 .family         = NFPROTO_UNSPEC,
 115                 .checkentry     = cgroup_mt_check_v0,
 116                 .match          = cgroup_mt_v0,
 117                 .matchsize      = sizeof(struct xt_cgroup_info_v0),
 118                 .me             = THIS_MODULE,
 119                 .hooks          = (1 << NF_INET_LOCAL_OUT) |
 120                                   (1 << NF_INET_POST_ROUTING) |
 121                                   (1 << NF_INET_LOCAL_IN),
 122         },
 123         {
 124                 .name           = "cgroup",
 125                 .revision       = 1,
 126                 .family         = NFPROTO_UNSPEC,
 127                 .checkentry     = cgroup_mt_check_v1,
 128                 .match          = cgroup_mt_v1,
 129                 .matchsize      = sizeof(struct xt_cgroup_info_v1),
 130                 .usersize       = offsetof(struct xt_cgroup_info_v1, priv),
 131                 .destroy        = cgroup_mt_destroy_v1,
 132                 .me             = THIS_MODULE,
 133                 .hooks          = (1 << NF_INET_LOCAL_OUT) |
 134                                   (1 << NF_INET_POST_ROUTING) |
 135                                   (1 << NF_INET_LOCAL_IN),
 136         },
 137 };
 138
 139 static int __init cgroup_mt_init(void)
 140 {
 141         return xt_register_matches(cgroup_mt_reg, ARRAY_SIZE(cgroup_mt_reg));
 142 }
 143
 144 static void __exit cgroup_mt_exit(void)
 145 {
 146         xt_unregister_matches(cgroup_mt_reg, ARRAY_SIZE(cgroup_mt_reg));
 147 }
 148
 149 module_init(cgroup_mt_init);
 150 module_exit(cgroup_mt_exit);