net/netfilter/xt_owner.c

   1 /*
   2  * Kernel module to match various things tied to sockets associated with
   3  * locally generated outgoing packets.
   4  *
   5  * (C) 2000 Marc Boucher <marc@mbsi.ca>
   6  *
   7  * Copyright © CC Computer Consultants GmbH, 2007 - 2008
   8  * <jengelh@computergmbh.de>
   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 #include <linux/module.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/file.h>
  17 #include <net/sock.h>
  18 #include <linux/netfilter/x_tables.h>
  19 #include <linux/netfilter/xt_owner.h>
  20 #include <linux/netfilter_ipv4/ipt_owner.h>
  21 #include <linux/netfilter_ipv6/ip6t_owner.h>
  22
  23 static bool
  24 owner_mt_v0(const struct sk_buff *skb, const struct xt_match_param *par)
  25 {
  26         const struct ipt_owner_info *info = par->matchinfo;
  27         const struct file *filp;
  28
  29         if (skb->sk == NULL || skb->sk->sk_socket == NULL)
  30                 return false;
  31
  32         filp = skb->sk->sk_socket->file;
  33         if (filp == NULL)
  34                 return false;
  35
  36         if (info->match & IPT_OWNER_UID)
  37                 if ((filp->f_cred->fsuid != info->uid) ^
  38                     !!(info->invert & IPT_OWNER_UID))
  39                         return false;
  40
  41         if (info->match & IPT_OWNER_GID)
  42                 if ((filp->f_cred->fsgid != info->gid) ^
  43                     !!(info->invert & IPT_OWNER_GID))
  44                         return false;
  45
  46         return true;
  47 }
  48
  49 static bool
  50 owner_mt6_v0(const struct sk_buff *skb, const struct xt_match_param *par)
  51 {
  52         const struct ip6t_owner_info *info = par->matchinfo;
  53         const struct file *filp;
  54
  55         if (skb->sk == NULL || skb->sk->sk_socket == NULL)
  56                 return false;
  57
  58         filp = skb->sk->sk_socket->file;
  59         if (filp == NULL)
  60                 return false;
  61
  62         if (info->match & IP6T_OWNER_UID)
  63                 if ((filp->f_cred->fsuid != info->uid) ^
  64                     !!(info->invert & IP6T_OWNER_UID))
  65                         return false;
  66
  67         if (info->match & IP6T_OWNER_GID)
  68                 if ((filp->f_cred->fsgid != info->gid) ^
  69                     !!(info->invert & IP6T_OWNER_GID))
  70                         return false;
  71
  72         return true;
  73 }
  74
  75 static bool
  76 owner_mt(const struct sk_buff *skb, const struct xt_match_param *par)
  77 {
  78         const struct xt_owner_match_info *info = par->matchinfo;
  79         const struct file *filp;
  80
  81         if (skb->sk == NULL || skb->sk->sk_socket == NULL)
  82                 return (info->match ^ info->invert) == 0;
  83         else if (info->match & info->invert & XT_OWNER_SOCKET)
  84                 /*
  85                  * Socket exists but user wanted ! --socket-exists.
  86                  * (Single ampersands intended.)
  87                  */
  88                 return false;
  89
  90         filp = skb->sk->sk_socket->file;
  91         if (filp == NULL)
  92                 return ((info->match ^ info->invert) &
  93                        (XT_OWNER_UID | XT_OWNER_GID)) == 0;
  94
  95         if (info->match & XT_OWNER_UID)
  96                 if ((filp->f_cred->fsuid >= info->uid_min &&
  97                     filp->f_cred->fsuid <= info->uid_max) ^
  98                     !(info->invert & XT_OWNER_UID))
  99                         return false;
 100
 101         if (info->match & XT_OWNER_GID)
 102                 if ((filp->f_cred->fsgid >= info->gid_min &&
 103                     filp->f_cred->fsgid <= info->gid_max) ^
 104                     !(info->invert & XT_OWNER_GID))
 105                         return false;
 106
 107         return true;
 108 }
 109
 110 static bool owner_mt_check_v0(const struct xt_mtchk_param *par)
 111 {
 112         const struct ipt_owner_info *info = par->matchinfo;
 113
 114         if (info->match & (IPT_OWNER_PID | IPT_OWNER_SID | IPT_OWNER_COMM)) {
 115                 printk(KERN_WARNING KBUILD_MODNAME
 116                        ": PID, SID and command matching is not "
 117                        "supported anymore\n");
 118                 return false;
 119         }
 120
 121         return true;
 122 }
 123
 124 static bool owner_mt6_check_v0(const struct xt_mtchk_param *par)
 125 {
 126         const struct ip6t_owner_info *info = par->matchinfo;
 127
 128         if (info->match & (IP6T_OWNER_PID | IP6T_OWNER_SID)) {
 129                 printk(KERN_WARNING KBUILD_MODNAME
 130                        ": PID and SID matching is not supported anymore\n");
 131                 return false;
 132         }
 133
 134         return true;
 135 }
 136
 137 static struct xt_match owner_mt_reg[] __read_mostly = {
 138         {
 139                 .name       = "owner",
 140                 .revision   = 0,
 141                 .family     = NFPROTO_IPV4,
 142                 .match      = owner_mt_v0,
 143                 .matchsize  = sizeof(struct ipt_owner_info),
 144                 .checkentry = owner_mt_check_v0,
 145                 .hooks      = (1 << NF_INET_LOCAL_OUT) |
 146                               (1 << NF_INET_POST_ROUTING),
 147                 .me         = THIS_MODULE,
 148         },
 149         {
 150                 .name       = "owner",
 151                 .revision   = 0,
 152                 .family     = NFPROTO_IPV6,
 153                 .match      = owner_mt6_v0,
 154                 .matchsize  = sizeof(struct ip6t_owner_info),
 155                 .checkentry = owner_mt6_check_v0,
 156                 .hooks      = (1 << NF_INET_LOCAL_OUT) |
 157                               (1 << NF_INET_POST_ROUTING),
 158                 .me         = THIS_MODULE,
 159         },
 160         {
 161                 .name       = "owner",
 162                 .revision   = 1,
 163                 .family     = NFPROTO_UNSPEC,
 164                 .match      = owner_mt,
 165                 .matchsize  = sizeof(struct xt_owner_match_info),
 166                 .hooks      = (1 << NF_INET_LOCAL_OUT) |
 167                               (1 << NF_INET_POST_ROUTING),
 168                 .me         = THIS_MODULE,
 169         },
 170 };
 171
 172 static int __init owner_mt_init(void)
 173 {
 174         return xt_register_matches(owner_mt_reg, ARRAY_SIZE(owner_mt_reg));
 175 }
 176
 177 static void __exit owner_mt_exit(void)
 178 {
 179         xt_unregister_matches(owner_mt_reg, ARRAY_SIZE(owner_mt_reg));
 180 }
 181
 182 module_init(owner_mt_init);
 183 module_exit(owner_mt_exit);
 184 MODULE_AUTHOR("Jan Engelhardt <jengelh@computergmbh.de>");
 185 MODULE_DESCRIPTION("Xtables: socket owner matching");
 186 MODULE_LICENSE("GPL");
 187 MODULE_ALIAS("ipt_owner");
 188 MODULE_ALIAS("ip6t_owner");