net/ipv4/netfilter/ipt_owner.c

   1 /* Kernel module to match various things tied to sockets associated with
   2    locally generated outgoing packets. */
   3
   4 /* (C) 2000 Marc Boucher <marc@mbsi.ca>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/file.h>
  14 #include <net/sock.h>
  15
  16 #include <linux/netfilter_ipv4/ipt_owner.h>
  17 #include <linux/netfilter_ipv4/ip_tables.h>
  18
  19 MODULE_LICENSE("GPL");
  20 MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
  21 MODULE_DESCRIPTION("iptables owner match");
  22
  23 static int
  24 match(const struct sk_buff *skb,
  25       const struct net_device *in,
  26       const struct net_device *out,
  27       const void *matchinfo,
  28       int offset,
  29       int *hotdrop)
  30 {
  31         const struct ipt_owner_info *info = matchinfo;
  32
  33         if (!skb->sk || !skb->sk->sk_socket || !skb->sk->sk_socket->file)
  34                 return 0;
  35
  36         if(info->match & IPT_OWNER_UID) {
  37                 if ((skb->sk->sk_socket->file->f_uid != info->uid) ^
  38                     !!(info->invert & IPT_OWNER_UID))
  39                         return 0;
  40         }
  41
  42         if(info->match & IPT_OWNER_GID) {
  43                 if ((skb->sk->sk_socket->file->f_gid != info->gid) ^
  44                     !!(info->invert & IPT_OWNER_GID))
  45                         return 0;
  46         }
  47
  48         return 1;
  49 }
  50
  51 static int
  52 checkentry(const char *tablename,
  53            const struct ipt_ip *ip,
  54            void *matchinfo,
  55            unsigned int matchsize,
  56            unsigned int hook_mask)
  57 {
  58         const struct ipt_owner_info *info = matchinfo;
  59
  60         if (hook_mask
  61             & ~((1 << NF_IP_LOCAL_OUT) | (1 << NF_IP_POST_ROUTING))) {
  62                 printk("ipt_owner: only valid for LOCAL_OUT or POST_ROUTING.\n");
  63                 return 0;
  64         }
  65
  66         if (matchsize != IPT_ALIGN(sizeof(struct ipt_owner_info))) {
  67                 printk("Matchsize %u != %Zu\n", matchsize,
  68                        IPT_ALIGN(sizeof(struct ipt_owner_info)));
  69                 return 0;
  70         }
  71
  72         if (info->match & (IPT_OWNER_PID|IPT_OWNER_SID|IPT_OWNER_COMM)) {
  73                 printk("ipt_owner: pid, sid and command matching "
  74                        "not supported anymore\n");
  75                 return 0;
  76         }
  77
  78         return 1;
  79 }
  80
  81 static struct ipt_match owner_match = {
  82         .name           = "owner",
  83         .match          = &match,
  84         .checkentry     = &checkentry,
  85         .me             = THIS_MODULE,
  86 };
  87
  88 static int __init init(void)
  89 {
  90         return ipt_register_match(&owner_match);
  91 }
  92
  93 static void __exit fini(void)
  94 {
  95         ipt_unregister_match(&owner_match);
  96 }
  97
  98 module_init(init);
  99 module_exit(fini);