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0265ab44 JE |
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 | * | |
edc26f7a | 7 | * Copyright © CC Computer Consultants GmbH, 2007 - 2008 |
0265ab44 JE |
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> | |
fdd723e2 | 17 | #include <net/inet_sock.h> |
0265ab44 JE |
18 | #include <linux/netfilter/x_tables.h> |
19 | #include <linux/netfilter/xt_owner.h> | |
0265ab44 | 20 | |
26711a79 EB |
21 | static int owner_check(const struct xt_mtchk_param *par) |
22 | { | |
23 | struct xt_owner_match_info *info = par->matchinfo; | |
9847371a | 24 | struct net *net = par->net; |
26711a79 | 25 | |
9847371a EB |
26 | /* Only allow the common case where the userns of the writer |
27 | * matches the userns of the network namespace. | |
28 | */ | |
26711a79 | 29 | if ((info->match & (XT_OWNER_UID|XT_OWNER_GID)) && |
9847371a | 30 | (current_user_ns() != net->user_ns)) |
26711a79 | 31 | return -EINVAL; |
9847371a EB |
32 | |
33 | /* Ensure the uids are valid */ | |
34 | if (info->match & XT_OWNER_UID) { | |
35 | kuid_t uid_min = make_kuid(net->user_ns, info->uid_min); | |
36 | kuid_t uid_max = make_kuid(net->user_ns, info->uid_max); | |
37 | ||
38 | if (!uid_valid(uid_min) || !uid_valid(uid_max) || | |
39 | (info->uid_max < info->uid_min) || | |
40 | uid_lt(uid_max, uid_min)) { | |
41 | return -EINVAL; | |
42 | } | |
43 | } | |
44 | ||
45 | /* Ensure the gids are valid */ | |
46 | if (info->match & XT_OWNER_GID) { | |
47 | kgid_t gid_min = make_kgid(net->user_ns, info->gid_min); | |
48 | kgid_t gid_max = make_kgid(net->user_ns, info->gid_max); | |
49 | ||
50 | if (!gid_valid(gid_min) || !gid_valid(gid_max) || | |
51 | (info->gid_max < info->gid_min) || | |
52 | gid_lt(gid_max, gid_min)) { | |
53 | return -EINVAL; | |
54 | } | |
55 | } | |
56 | ||
26711a79 EB |
57 | return 0; |
58 | } | |
59 | ||
0265ab44 | 60 | static bool |
62fc8051 | 61 | owner_mt(const struct sk_buff *skb, struct xt_action_param *par) |
0265ab44 | 62 | { |
f7108a20 | 63 | const struct xt_owner_match_info *info = par->matchinfo; |
0265ab44 | 64 | const struct file *filp; |
fdd723e2 | 65 | struct sock *sk = skb_to_full_sk(skb); |
613dbd95 | 66 | struct net *net = xt_net(par); |
0265ab44 | 67 | |
fdd723e2 | 68 | if (sk == NULL || sk->sk_socket == NULL) |
0265ab44 JE |
69 | return (info->match ^ info->invert) == 0; |
70 | else if (info->match & info->invert & XT_OWNER_SOCKET) | |
71 | /* | |
72 | * Socket exists but user wanted ! --socket-exists. | |
73 | * (Single ampersands intended.) | |
74 | */ | |
75 | return false; | |
76 | ||
fdd723e2 | 77 | filp = sk->sk_socket->file; |
0265ab44 JE |
78 | if (filp == NULL) |
79 | return ((info->match ^ info->invert) & | |
80 | (XT_OWNER_UID | XT_OWNER_GID)) == 0; | |
81 | ||
26711a79 | 82 | if (info->match & XT_OWNER_UID) { |
9847371a EB |
83 | kuid_t uid_min = make_kuid(net->user_ns, info->uid_min); |
84 | kuid_t uid_max = make_kuid(net->user_ns, info->uid_max); | |
26711a79 EB |
85 | if ((uid_gte(filp->f_cred->fsuid, uid_min) && |
86 | uid_lte(filp->f_cred->fsuid, uid_max)) ^ | |
edc26f7a | 87 | !(info->invert & XT_OWNER_UID)) |
0265ab44 | 88 | return false; |
26711a79 | 89 | } |
0265ab44 | 90 | |
26711a79 | 91 | if (info->match & XT_OWNER_GID) { |
9847371a EB |
92 | kgid_t gid_min = make_kgid(net->user_ns, info->gid_min); |
93 | kgid_t gid_max = make_kgid(net->user_ns, info->gid_max); | |
26711a79 EB |
94 | if ((gid_gte(filp->f_cred->fsgid, gid_min) && |
95 | gid_lte(filp->f_cred->fsgid, gid_max)) ^ | |
edc26f7a | 96 | !(info->invert & XT_OWNER_GID)) |
0265ab44 | 97 | return false; |
26711a79 | 98 | } |
0265ab44 JE |
99 | |
100 | return true; | |
101 | } | |
102 | ||
6461caed JE |
103 | static struct xt_match owner_mt_reg __read_mostly = { |
104 | .name = "owner", | |
105 | .revision = 1, | |
106 | .family = NFPROTO_UNSPEC, | |
26711a79 | 107 | .checkentry = owner_check, |
6461caed JE |
108 | .match = owner_mt, |
109 | .matchsize = sizeof(struct xt_owner_match_info), | |
110 | .hooks = (1 << NF_INET_LOCAL_OUT) | | |
111 | (1 << NF_INET_POST_ROUTING), | |
112 | .me = THIS_MODULE, | |
0265ab44 JE |
113 | }; |
114 | ||
115 | static int __init owner_mt_init(void) | |
116 | { | |
6461caed | 117 | return xt_register_match(&owner_mt_reg); |
0265ab44 JE |
118 | } |
119 | ||
120 | static void __exit owner_mt_exit(void) | |
121 | { | |
6461caed | 122 | xt_unregister_match(&owner_mt_reg); |
0265ab44 JE |
123 | } |
124 | ||
125 | module_init(owner_mt_init); | |
126 | module_exit(owner_mt_exit); | |
6461caed | 127 | MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>"); |
2ae15b64 | 128 | MODULE_DESCRIPTION("Xtables: socket owner matching"); |
0265ab44 JE |
129 | MODULE_LICENSE("GPL"); |
130 | MODULE_ALIAS("ipt_owner"); | |
131 | MODULE_ALIAS("ip6t_owner"); |