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   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
   8  * Contact: <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 net_device *in,
  25             const struct net_device *out, const struct xt_match *match,
  26             const void *matchinfo, int offset, unsigned int protoff,
  27             bool *hotdrop)
  28 {
  29         const struct ipt_owner_info *info = matchinfo;
  30         const struct file *filp;
  31
  32         if (skb->sk == NULL || skb->sk->sk_socket == NULL)
  33                 return false;
  34
  35         filp = skb->sk->sk_socket->file;
  36         if (filp == NULL)
  37                 return false;
  38
  39         if (info->match & IPT_OWNER_UID)
  40                 if ((filp->f_uid != info->uid) ^
  41                     !!(info->invert & IPT_OWNER_UID))
  42                         return false;
  43
  44         if (info->match & IPT_OWNER_GID)
  45                 if ((filp->f_gid != info->gid) ^
  46                     !!(info->invert & IPT_OWNER_GID))
  47                         return false;
  48
  49         return true;
  50 }
  51
  52 static bool
  53 owner_mt6_v0(const struct sk_buff *skb, const struct net_device *in,
  54              const struct net_device *out, const struct xt_match *match,
  55              const void *matchinfo, int offset, unsigned int protoff,
  56              bool *hotdrop)
  57 {
  58         const struct ip6t_owner_info *info = matchinfo;
  59         const struct file *filp;
  60
  61         if (skb->sk == NULL || skb->sk->sk_socket == NULL)
  62                 return false;
  63
  64         filp = skb->sk->sk_socket->file;
  65         if (filp == NULL)
  66                 return false;
  67
  68         if (info->match & IP6T_OWNER_UID)
  69                 if ((filp->f_uid != info->uid) ^
  70                     !!(info->invert & IP6T_OWNER_UID))
  71                         return false;
  72
  73         if (info->match & IP6T_OWNER_GID)
  74                 if ((filp->f_gid != info->gid) ^
  75                     !!(info->invert & IP6T_OWNER_GID))
  76                         return false;
  77
  78         return true;
  79 }
  80
  81 static bool
  82 owner_mt(const struct sk_buff *skb, const struct net_device *in,
  83          const struct net_device *out, const struct xt_match *match,
  84          const void *matchinfo, int offset, unsigned int protoff,
  85          bool *hotdrop)
  86 {
  87         const struct xt_owner_match_info *info = matchinfo;
  88         const struct file *filp;
  89
  90         if (skb->sk == NULL || skb->sk->sk_socket == NULL)
  91                 return (info->match ^ info->invert) == 0;
  92         else if (info->match & info->invert & XT_OWNER_SOCKET)
  93                 /*
  94                  * Socket exists but user wanted ! --socket-exists.
  95                  * (Single ampersands intended.)
  96                  */
  97                 return false;
  98
  99         filp = skb->sk->sk_socket->file;
 100         if (filp == NULL)
 101                 return ((info->match ^ info->invert) &
 102                        (XT_OWNER_UID | XT_OWNER_GID)) == 0;
 103
 104         if (info->match & XT_OWNER_UID)
 105                 if ((filp->f_uid != info->uid) ^
 106                     !!(info->invert & XT_OWNER_UID))
 107                         return false;
 108
 109         if (info->match & XT_OWNER_GID)
 110                 if ((filp->f_gid != info->gid) ^
 111                     !!(info->invert & XT_OWNER_GID))
 112                         return false;
 113
 114         return true;
 115 }
 116
 117 static bool
 118 owner_mt_check_v0(const char *tablename, const void *ip,
 119                   const struct xt_match *match, void *matchinfo,
 120                   unsigned int hook_mask)
 121 {
 122         const struct ipt_owner_info *info = matchinfo;
 123
 124         if (info->match & (IPT_OWNER_PID | IPT_OWNER_SID | IPT_OWNER_COMM)) {
 125                 printk(KERN_WARNING KBUILD_MODNAME
 126                        ": PID, SID and command matching is not "
 127                        "supported anymore\n");
 128                 return false;
 129         }
 130
 131         return true;
 132 }
 133
 134 static bool
 135 owner_mt6_check_v0(const char *tablename, const void *ip,
 136                    const struct xt_match *match, void *matchinfo,
 137                    unsigned int hook_mask)
 138 {
 139         const struct ip6t_owner_info *info = matchinfo;
 140
 141         if (info->match & (IP6T_OWNER_PID | IP6T_OWNER_SID)) {
 142                 printk(KERN_WARNING KBUILD_MODNAME
 143                        ": PID and SID matching is not supported anymore\n");
 144                 return false;
 145         }
 146
 147         return true;
 148 }
 149
 150 static struct xt_match owner_mt_reg[] __read_mostly = {
 151         {
 152                 .name       = "owner",
 153                 .revision   = 0,
 154                 .family     = AF_INET,
 155                 .match      = owner_mt_v0,
 156                 .matchsize  = sizeof(struct ipt_owner_info),
 157                 .checkentry = owner_mt_check_v0,
 158                 .hooks      = (1 << NF_INET_LOCAL_OUT) |
 159                               (1 << NF_INET_POST_ROUTING),
 160                 .me         = THIS_MODULE,
 161         },
 162         {
 163                 .name       = "owner",
 164                 .revision   = 0,
 165                 .family     = AF_INET6,
 166                 .match      = owner_mt6_v0,
 167                 .matchsize  = sizeof(struct ip6t_owner_info),
 168                 .checkentry = owner_mt6_check_v0,
 169                 .hooks      = (1 << NF_INET_LOCAL_OUT) |
 170                               (1 << NF_INET_POST_ROUTING),
 171                 .me         = THIS_MODULE,
 172         },
 173         {
 174                 .name       = "owner",
 175                 .revision   = 1,
 176                 .family     = AF_INET,
 177                 .match      = owner_mt,
 178                 .matchsize  = sizeof(struct xt_owner_match_info),
 179                 .hooks      = (1 << NF_INET_LOCAL_OUT) |
 180                               (1 << NF_INET_POST_ROUTING),
 181                 .me         = THIS_MODULE,
 182         },
 183         {
 184                 .name       = "owner",
 185                 .revision   = 1,
 186                 .family     = AF_INET6,
 187                 .match      = owner_mt,
 188                 .matchsize  = sizeof(struct xt_owner_match_info),
 189                 .hooks      = (1 << NF_INET_LOCAL_OUT) |
 190                               (1 << NF_INET_POST_ROUTING),
 191                 .me         = THIS_MODULE,
 192         },
 193 };
 194
 195 static int __init owner_mt_init(void)
 196 {
 197         return xt_register_matches(owner_mt_reg, ARRAY_SIZE(owner_mt_reg));
 198 }
 199
 200 static void __exit owner_mt_exit(void)
 201 {
 202         xt_unregister_matches(owner_mt_reg, ARRAY_SIZE(owner_mt_reg));
 203 }
 204
 205 module_init(owner_mt_init);
 206 module_exit(owner_mt_exit);
 207 MODULE_AUTHOR("Jan Engelhardt <jengelh@computergmbh.de>");
 208 MODULE_DESCRIPTION("Xtables: socket owner matching");
 209 MODULE_LICENSE("GPL");
 210 MODULE_ALIAS("ipt_owner");
 211 MODULE_ALIAS("ip6t_owner");