1 /*
2 * Xtables module to match the process control group.
3 *
4 * Might be used to implement individual "per-application" firewall
5 * policies in contrast to global policies based on control groups.
6 * Matching is based upon processes tagged to net_cls' classid marker.
7 *
8 * (C) 2013 Daniel Borkmann <dborkman@redhat.com>
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
15 #include <linux/skbuff.h>
16 #include <linux/module.h>
17 #include <linux/netfilter/x_tables.h>
18 #include <linux/netfilter/xt_cgroup.h>
19 #include <net/sock.h>
20
21 MODULE_LICENSE("GPL");
22 MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
23 MODULE_DESCRIPTION("Xtables: process control group matching");
24 MODULE_ALIAS("ipt_cgroup");
25 MODULE_ALIAS("ip6t_cgroup");
26
27 static int cgroup_mt_check_v0(const struct xt_mtchk_param *par)
28 {
29 struct xt_cgroup_info_v0 *info = par->matchinfo;
30
31 if (info->invert & ~1)
32 return -EINVAL;
33
34 return 0;
35 }
36
37 static int cgroup_mt_check_v1(const struct xt_mtchk_param *par)
38 {
39 struct xt_cgroup_info_v1 *info = par->matchinfo;
40 struct cgroup *cgrp;
41
42 if ((info->invert_path & ~1) || (info->invert_classid & ~1))
43 return -EINVAL;
44
45 if (!info->has_path && !info->has_classid) {
46 pr_info("xt_cgroup: no path or classid specified\n");
47 return -EINVAL;
48 }
49
50 if (info->has_path && info->has_classid) {
51 pr_info("xt_cgroup: both path and classid specified\n");
52 return -EINVAL;
53 }
54
55 if (info->has_path) {
56 cgrp = cgroup_get_from_path(info->path);
57 if (IS_ERR(cgrp)) {
58 pr_info("xt_cgroup: invalid path, errno=%ld\n",
59 PTR_ERR(cgrp));
60 return -EINVAL;
61 }
62 info->priv = cgrp;
63 }
64
65 return 0;
66 }
67
68 static bool
69 cgroup_mt_v0(const struct sk_buff *skb, struct xt_action_param *par)
70 {
71 const struct xt_cgroup_info_v0 *info = par->matchinfo;
72
73 if (skb->sk == NULL || !sk_fullsock(skb->sk))
74 return false;
75
76 return (info->id == sock_cgroup_classid(&skb->sk->sk_cgrp_data)) ^
77 info->invert;
78 }
79
80 static bool cgroup_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
81 {
82 const struct xt_cgroup_info_v1 *info = par->matchinfo;
83 struct sock_cgroup_data *skcd = &skb->sk->sk_cgrp_data;
84 struct cgroup *ancestor = info->priv;
85
86 if (!skb->sk || !sk_fullsock(skb->sk))
87 return false;
88
89 if (ancestor)
90 return cgroup_is_descendant(sock_cgroup_ptr(skcd), ancestor) ^
91 info->invert_path;
92 else
93 return (info->classid == sock_cgroup_classid(skcd)) ^
94 info->invert_classid;
95 }
96
97 static void cgroup_mt_destroy_v1(const struct xt_mtdtor_param *par)
98 {
99 struct xt_cgroup_info_v1 *info = par->matchinfo;
100
101 if (info->priv)
102 cgroup_put(info->priv);
103 }
104
105 static struct xt_match cgroup_mt_reg[] __read_mostly = {
106 {
107 .name = "cgroup",
108 .revision = 0,
109 .family = NFPROTO_UNSPEC,
110 .checkentry = cgroup_mt_check_v0,
111 .match = cgroup_mt_v0,
112 .matchsize = sizeof(struct xt_cgroup_info_v0),
113 .me = THIS_MODULE,
114 .hooks = (1 << NF_INET_LOCAL_OUT) |
115 (1 << NF_INET_POST_ROUTING) |
116 (1 << NF_INET_LOCAL_IN),
117 },
118 {
119 .name = "cgroup",
120 .revision = 1,
121 .family = NFPROTO_UNSPEC,
122 .checkentry = cgroup_mt_check_v1,
123 .match = cgroup_mt_v1,
124 .matchsize = sizeof(struct xt_cgroup_info_v1),
125 .usersize = offsetof(struct xt_cgroup_info_v1, priv),
126 .destroy = cgroup_mt_destroy_v1,
127 .me = THIS_MODULE,
128 .hooks = (1 << NF_INET_LOCAL_OUT) |
129 (1 << NF_INET_POST_ROUTING) |
130 (1 << NF_INET_LOCAL_IN),
131 },
132 };
133
134 static int __init cgroup_mt_init(void)
135 {
136 return xt_register_matches(cgroup_mt_reg, ARRAY_SIZE(cgroup_mt_reg));
137 }
138
139 static void __exit cgroup_mt_exit(void)
140 {
141 xt_unregister_matches(cgroup_mt_reg, ARRAY_SIZE(cgroup_mt_reg));
142 }
143
144 module_init(cgroup_mt_init);
145 module_exit(cgroup_mt_exit);
146
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