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 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_min &&
 106                     filp->f_uid <= info->uid_max) ^
 107                     !(info->invert & XT_OWNER_UID))
 108                         return false;
 109
 110         if (info->match & XT_OWNER_GID)
 111                 if ((filp->f_gid >= info->gid_min &&
 112                     filp->f_gid <= info->gid_max) ^
 113                     !(info->invert & XT_OWNER_GID))
 114                         return false;
 115
 116         return true;
 117 }
 118
 119 static bool
 120 owner_mt_check_v0(const char *tablename, const void *ip,
 121                   const struct xt_match *match, void *matchinfo,
 122                   unsigned int hook_mask)
 123 {
 124         const struct ipt_owner_info *info = matchinfo;
 125
 126         if (info->match & (IPT_OWNER_PID | IPT_OWNER_SID | IPT_OWNER_COMM)) {
 127                 printk(KERN_WARNING KBUILD_MODNAME
 128                        ": PID, SID and command matching is not "
 129                        "supported anymore\n");
 130                 return false;
 131         }
 132
 133         return true;
 134 }
 135
 136 static bool
 137 owner_mt6_check_v0(const char *tablename, const void *ip,
 138                    const struct xt_match *match, void *matchinfo,
 139                    unsigned int hook_mask)
 140 {
 141         const struct ip6t_owner_info *info = matchinfo;
 142
 143         if (info->match & (IP6T_OWNER_PID | IP6T_OWNER_SID)) {
 144                 printk(KERN_WARNING KBUILD_MODNAME
 145                        ": PID and SID matching is not supported anymore\n");
 146                 return false;
 147         }
 148
 149         return true;
 150 }
 151
 152 static struct xt_match owner_mt_reg[] __read_mostly = {
 153         {
 154                 .name       = "owner",
 155                 .revision   = 0,
 156                 .family     = AF_INET,
 157                 .match      = owner_mt_v0,
 158                 .matchsize  = sizeof(struct ipt_owner_info),
 159                 .checkentry = owner_mt_check_v0,
 160                 .hooks      = (1 << NF_INET_LOCAL_OUT) |
 161                               (1 << NF_INET_POST_ROUTING),
 162                 .me         = THIS_MODULE,
 163         },
 164         {
 165                 .name       = "owner",
 166                 .revision   = 0,
 167                 .family     = AF_INET6,
 168                 .match      = owner_mt6_v0,
 169                 .matchsize  = sizeof(struct ip6t_owner_info),
 170                 .checkentry = owner_mt6_check_v0,
 171                 .hooks      = (1 << NF_INET_LOCAL_OUT) |
 172                               (1 << NF_INET_POST_ROUTING),
 173                 .me         = THIS_MODULE,
 174         },
 175         {
 176                 .name       = "owner",
 177                 .revision   = 1,
 178                 .family     = AF_INET,
 179                 .match      = owner_mt,
 180                 .matchsize  = sizeof(struct xt_owner_match_info),
 181                 .hooks      = (1 << NF_INET_LOCAL_OUT) |
 182                               (1 << NF_INET_POST_ROUTING),
 183                 .me         = THIS_MODULE,
 184         },
 185         {
 186                 .name       = "owner",
 187                 .revision   = 1,
 188                 .family     = AF_INET6,
 189                 .match      = owner_mt,
 190                 .matchsize  = sizeof(struct xt_owner_match_info),
 191                 .hooks      = (1 << NF_INET_LOCAL_OUT) |
 192                               (1 << NF_INET_POST_ROUTING),
 193                 .me         = THIS_MODULE,
 194         },
 195 };
 196
 197 static int __init owner_mt_init(void)
 198 {
 199         return xt_register_matches(owner_mt_reg, ARRAY_SIZE(owner_mt_reg));
 200 }
 201
 202 static void __exit owner_mt_exit(void)
 203 {
 204         xt_unregister_matches(owner_mt_reg, ARRAY_SIZE(owner_mt_reg));
 205 }
 206
 207 module_init(owner_mt_init);
 208 module_exit(owner_mt_exit);
 209 MODULE_AUTHOR("Jan Engelhardt <jengelh@computergmbh.de>");
 210 MODULE_DESCRIPTION("Xtables: socket owner matching");
 211 MODULE_LICENSE("GPL");
 212 MODULE_ALIAS("ipt_owner");
 213 MODULE_ALIAS("ip6t_owner");