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 int cgroup_mt_check_v2(const struct xt_mtchk_param *par)
  72 {
  73         struct xt_cgroup_info_v2 *info = par->matchinfo;
  74         struct cgroup *cgrp;
  75
  76         if ((info->invert_path & ~1) || (info->invert_classid & ~1))
  77                 return -EINVAL;
  78
  79         if (!info->has_path && !info->has_classid) {
  80                 pr_info("xt_cgroup: no path or classid specified\n");
  81                 return -EINVAL;
  82         }
  83
  84         if (info->has_path && info->has_classid) {
  85                 pr_info_ratelimited("path and classid specified\n");
  86                 return -EINVAL;
  87         }
  88
  89         info->priv = NULL;
  90         if (info->has_path) {
  91                 cgrp = cgroup_get_from_path(info->path);
  92                 if (IS_ERR(cgrp)) {
  93                         pr_info_ratelimited("invalid path, errno=%ld\n",
  94                                             PTR_ERR(cgrp));
  95                         return -EINVAL;
  96                 }
  97                 info->priv = cgrp;
  98         }
  99
 100         return 0;
 101 }
 102
 103 static bool
 104 cgroup_mt_v0(const struct sk_buff *skb, struct xt_action_param *par)
 105 {
 106         const struct xt_cgroup_info_v0 *info = par->matchinfo;
 107         struct sock *sk = skb->sk;
 108
 109         if (!sk || !sk_fullsock(sk) || !net_eq(xt_net(par), sock_net(sk)))
 110                 return false;
 111
 112         return (info->id == sock_cgroup_classid(&skb->sk->sk_cgrp_data)) ^
 113                 info->invert;
 114 }
 115
 116 static bool cgroup_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
 117 {
 118         const struct xt_cgroup_info_v1 *info = par->matchinfo;
 119         struct sock_cgroup_data *skcd = &skb->sk->sk_cgrp_data;
 120         struct cgroup *ancestor = info->priv;
 121         struct sock *sk = skb->sk;
 122
 123         if (!sk || !sk_fullsock(sk) || !net_eq(xt_net(par), sock_net(sk)))
 124                 return false;
 125
 126         if (ancestor)
 127                 return cgroup_is_descendant(sock_cgroup_ptr(skcd), ancestor) ^
 128                         info->invert_path;
 129         else
 130                 return (info->classid == sock_cgroup_classid(skcd)) ^
 131                         info->invert_classid;
 132 }
 133
 134 static bool cgroup_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
 135 {
 136         const struct xt_cgroup_info_v2 *info = par->matchinfo;
 137         struct sock_cgroup_data *skcd = &skb->sk->sk_cgrp_data;
 138         struct cgroup *ancestor = info->priv;
 139         struct sock *sk = skb->sk;
 140
 141         if (!sk || !sk_fullsock(sk) || !net_eq(xt_net(par), sock_net(sk)))
 142                 return false;
 143
 144         if (ancestor)
 145                 return cgroup_is_descendant(sock_cgroup_ptr(skcd), ancestor) ^
 146                         info->invert_path;
 147         else
 148                 return (info->classid == sock_cgroup_classid(skcd)) ^
 149                         info->invert_classid;
 150 }
 151
 152 static void cgroup_mt_destroy_v1(const struct xt_mtdtor_param *par)
 153 {
 154         struct xt_cgroup_info_v1 *info = par->matchinfo;
 155
 156         if (info->priv)
 157                 cgroup_put(info->priv);
 158 }
 159
 160 static void cgroup_mt_destroy_v2(const struct xt_mtdtor_param *par)
 161 {
 162         struct xt_cgroup_info_v2 *info = par->matchinfo;
 163
 164         if (info->priv)
 165                 cgroup_put(info->priv);
 166 }
 167
 168 static struct xt_match cgroup_mt_reg[] __read_mostly = {
 169         {
 170                 .name           = "cgroup",
 171                 .revision       = 0,
 172                 .family         = NFPROTO_UNSPEC,
 173                 .checkentry     = cgroup_mt_check_v0,
 174                 .match          = cgroup_mt_v0,
 175                 .matchsize      = sizeof(struct xt_cgroup_info_v0),
 176                 .me             = THIS_MODULE,
 177                 .hooks          = (1 << NF_INET_LOCAL_OUT) |
 178                                   (1 << NF_INET_POST_ROUTING) |
 179                                   (1 << NF_INET_LOCAL_IN),
 180         },
 181         {
 182                 .name           = "cgroup",
 183                 .revision       = 1,
 184                 .family         = NFPROTO_UNSPEC,
 185                 .checkentry     = cgroup_mt_check_v1,
 186                 .match          = cgroup_mt_v1,
 187                 .matchsize      = sizeof(struct xt_cgroup_info_v1),
 188                 .usersize       = offsetof(struct xt_cgroup_info_v1, priv),
 189                 .destroy        = cgroup_mt_destroy_v1,
 190                 .me             = THIS_MODULE,
 191                 .hooks          = (1 << NF_INET_LOCAL_OUT) |
 192                                   (1 << NF_INET_POST_ROUTING) |
 193                                   (1 << NF_INET_LOCAL_IN),
 194         },
 195         {
 196                 .name           = "cgroup",
 197                 .revision       = 2,
 198                 .family         = NFPROTO_UNSPEC,
 199                 .checkentry     = cgroup_mt_check_v2,
 200                 .match          = cgroup_mt_v2,
 201                 .matchsize      = sizeof(struct xt_cgroup_info_v2),
 202                 .usersize       = offsetof(struct xt_cgroup_info_v2, priv),
 203                 .destroy        = cgroup_mt_destroy_v2,
 204                 .me             = THIS_MODULE,
 205                 .hooks          = (1 << NF_INET_LOCAL_OUT) |
 206                                   (1 << NF_INET_POST_ROUTING) |
 207                                   (1 << NF_INET_LOCAL_IN),
 208         },
 209 };
 210
 211 static int __init cgroup_mt_init(void)
 212 {
 213         return xt_register_matches(cgroup_mt_reg, ARRAY_SIZE(cgroup_mt_reg));
 214 }
 215
 216 static void __exit cgroup_mt_exit(void)
 217 {
 218         xt_unregister_matches(cgroup_mt_reg, ARRAY_SIZE(cgroup_mt_reg));
 219 }
 220
 221 module_init(cgroup_mt_init);
 222 module_exit(cgroup_mt_exit);