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 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12 */
13 #include <linux/module.h>
14 #include <linux/skbuff.h>
15 #include <linux/file.h>
16 #include <net/sock.h>
17 #include <linux/netfilter/x_tables.h>
18 #include <linux/netfilter/xt_owner.h>
19
20 static bool
owner_mt(const struct sk_buff * skb,struct xt_action_param * par)21 owner_mt(const struct sk_buff *skb, struct xt_action_param *par)
22 {
23 const struct xt_owner_match_info *info = par->matchinfo;
24 const struct file *filp;
25
26 if (skb->sk == NULL || skb->sk->sk_socket == NULL)
27 return (info->match ^ info->invert) == 0;
28 else if (info->match & info->invert & XT_OWNER_SOCKET)
29 /*
30 * Socket exists but user wanted ! --socket-exists.
31 * (Single ampersands intended.)
32 */
33 return false;
34
35 filp = skb->sk->sk_socket->file;
36 if (filp == NULL)
37 return ((info->match ^ info->invert) &
38 (XT_OWNER_UID | XT_OWNER_GID)) == 0;
39
40 if (info->match & XT_OWNER_UID)
41 if ((filp->f_cred->fsuid >= info->uid_min &&
42 filp->f_cred->fsuid <= info->uid_max) ^
43 !(info->invert & XT_OWNER_UID))
44 return false;
45
46 if (info->match & XT_OWNER_GID)
47 if ((filp->f_cred->fsgid >= info->gid_min &&
48 filp->f_cred->fsgid <= info->gid_max) ^
49 !(info->invert & XT_OWNER_GID))
50 return false;
51
52 return true;
53 }
54
55 static struct xt_match owner_mt_reg __read_mostly = {
56 .name = "owner",
57 .revision = 1,
58 .family = NFPROTO_UNSPEC,
59 .match = owner_mt,
60 .matchsize = sizeof(struct xt_owner_match_info),
61 .hooks = (1 << NF_INET_LOCAL_OUT) |
62 (1 << NF_INET_POST_ROUTING),
63 .me = THIS_MODULE,
64 };
65
owner_mt_init(void)66 static int __init owner_mt_init(void)
67 {
68 return xt_register_match(&owner_mt_reg);
69 }
70
owner_mt_exit(void)71 static void __exit owner_mt_exit(void)
72 {
73 xt_unregister_match(&owner_mt_reg);
74 }
75
76 module_init(owner_mt_init);
77 module_exit(owner_mt_exit);
78 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
79 MODULE_DESCRIPTION("Xtables: socket owner matching");
80 MODULE_LICENSE("GPL");
81 MODULE_ALIAS("ipt_owner");
82 MODULE_ALIAS("ip6t_owner");
83