Linux kernel mirror (for testing)
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linux
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Xtables module to match the process control group.
4 *
5 * Might be used to implement individual "per-application" firewall
6 * policies in contrast to global policies based on control groups.
7 * Matching is based upon processes tagged to net_cls' classid marker.
8 *
9 * (C) 2013 Daniel Borkmann <dborkman@redhat.com>
10 */
11
12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14#include <linux/skbuff.h>
15#include <linux/module.h>
16#include <linux/netfilter/x_tables.h>
17#include <linux/netfilter/xt_cgroup.h>
18#include <net/sock.h>
19
20MODULE_LICENSE("GPL");
21MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
22MODULE_DESCRIPTION("Xtables: process control group matching");
23MODULE_ALIAS("ipt_cgroup");
24MODULE_ALIAS("ip6t_cgroup");
25
26#define NET_CLS_CLASSID_INVALID_MSG "xt_cgroup: classid invalid without net_cls cgroups\n"
27
28static int cgroup_mt_check_v0(const struct xt_mtchk_param *par)
29{
30 struct xt_cgroup_info_v0 *info = par->matchinfo;
31
32 if (info->invert & ~1)
33 return -EINVAL;
34
35 if (!IS_ENABLED(CONFIG_CGROUP_NET_CLASSID)) {
36 pr_info(NET_CLS_CLASSID_INVALID_MSG);
37 return -EINVAL;
38 }
39
40 return 0;
41}
42
43static int cgroup_mt_check_v1(const struct xt_mtchk_param *par)
44{
45 struct xt_cgroup_info_v1 *info = par->matchinfo;
46 struct cgroup *cgrp;
47
48 if ((info->invert_path & ~1) || (info->invert_classid & ~1))
49 return -EINVAL;
50
51 if (!info->has_path && !info->has_classid) {
52 pr_info("xt_cgroup: no path or classid specified\n");
53 return -EINVAL;
54 }
55
56 if (info->has_path && info->has_classid) {
57 pr_info_ratelimited("path and classid specified\n");
58 return -EINVAL;
59 }
60
61 if (info->has_classid && !IS_ENABLED(CONFIG_CGROUP_NET_CLASSID)) {
62 pr_info(NET_CLS_CLASSID_INVALID_MSG);
63 return -EINVAL;
64 }
65
66 info->priv = NULL;
67 if (info->has_path) {
68 cgrp = cgroup_get_from_path(info->path);
69 if (IS_ERR(cgrp)) {
70 pr_info_ratelimited("invalid path, errno=%ld\n",
71 PTR_ERR(cgrp));
72 return -EINVAL;
73 }
74 info->priv = cgrp;
75 }
76
77 return 0;
78}
79
80static int cgroup_mt_check_v2(const struct xt_mtchk_param *par)
81{
82 struct xt_cgroup_info_v2 *info = par->matchinfo;
83 struct cgroup *cgrp;
84
85 if ((info->invert_path & ~1) || (info->invert_classid & ~1))
86 return -EINVAL;
87
88 if (!info->has_path && !info->has_classid) {
89 pr_info("xt_cgroup: no path or classid specified\n");
90 return -EINVAL;
91 }
92
93 if (info->has_path && info->has_classid) {
94 pr_info_ratelimited("path and classid specified\n");
95 return -EINVAL;
96 }
97
98 if (info->has_classid && !IS_ENABLED(CONFIG_CGROUP_NET_CLASSID)) {
99 pr_info(NET_CLS_CLASSID_INVALID_MSG);
100 return -EINVAL;
101 }
102
103 info->priv = NULL;
104 if (info->has_path) {
105 cgrp = cgroup_get_from_path(info->path);
106 if (IS_ERR(cgrp)) {
107 pr_info_ratelimited("invalid path, errno=%ld\n",
108 PTR_ERR(cgrp));
109 return -EINVAL;
110 }
111 info->priv = cgrp;
112 }
113
114 return 0;
115}
116
117static bool
118cgroup_mt_v0(const struct sk_buff *skb, struct xt_action_param *par)
119{
120#ifdef CONFIG_CGROUP_NET_CLASSID
121 const struct xt_cgroup_info_v0 *info = par->matchinfo;
122 struct sock *sk = skb->sk;
123
124 if (!sk || !sk_fullsock(sk) || !net_eq(xt_net(par), sock_net(sk)))
125 return false;
126
127 return (info->id == sock_cgroup_classid(&skb->sk->sk_cgrp_data)) ^
128 info->invert;
129#endif
130 return false;
131}
132
133static bool cgroup_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
134{
135 const struct xt_cgroup_info_v1 *info = par->matchinfo;
136 struct sock_cgroup_data *skcd = &skb->sk->sk_cgrp_data;
137 struct cgroup *ancestor = info->priv;
138 struct sock *sk = skb->sk;
139
140 if (!sk || !sk_fullsock(sk) || !net_eq(xt_net(par), sock_net(sk)))
141 return false;
142
143 if (ancestor)
144 return cgroup_is_descendant(sock_cgroup_ptr(skcd), ancestor) ^
145 info->invert_path;
146#ifdef CONFIG_CGROUP_NET_CLASSID
147 else
148 return (info->classid == sock_cgroup_classid(skcd)) ^
149 info->invert_classid;
150#endif
151 return false;
152}
153
154static bool cgroup_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
155{
156 const struct xt_cgroup_info_v2 *info = par->matchinfo;
157 struct sock_cgroup_data *skcd = &skb->sk->sk_cgrp_data;
158 struct cgroup *ancestor = info->priv;
159 struct sock *sk = skb->sk;
160
161 if (!sk || !sk_fullsock(sk) || !net_eq(xt_net(par), sock_net(sk)))
162 return false;
163
164 if (ancestor)
165 return cgroup_is_descendant(sock_cgroup_ptr(skcd), ancestor) ^
166 info->invert_path;
167#ifdef CONFIG_CGROUP_NET_CLASSID
168 else
169 return (info->classid == sock_cgroup_classid(skcd)) ^
170 info->invert_classid;
171#endif
172 return false;
173}
174
175static void cgroup_mt_destroy_v1(const struct xt_mtdtor_param *par)
176{
177 struct xt_cgroup_info_v1 *info = par->matchinfo;
178
179 if (info->priv)
180 cgroup_put(info->priv);
181}
182
183static void cgroup_mt_destroy_v2(const struct xt_mtdtor_param *par)
184{
185 struct xt_cgroup_info_v2 *info = par->matchinfo;
186
187 if (info->priv)
188 cgroup_put(info->priv);
189}
190
191static struct xt_match cgroup_mt_reg[] __read_mostly = {
192 {
193 .name = "cgroup",
194 .revision = 0,
195 .family = NFPROTO_UNSPEC,
196 .checkentry = cgroup_mt_check_v0,
197 .match = cgroup_mt_v0,
198 .matchsize = sizeof(struct xt_cgroup_info_v0),
199 .me = THIS_MODULE,
200 .hooks = (1 << NF_INET_LOCAL_OUT) |
201 (1 << NF_INET_POST_ROUTING) |
202 (1 << NF_INET_LOCAL_IN),
203 },
204 {
205 .name = "cgroup",
206 .revision = 1,
207 .family = NFPROTO_UNSPEC,
208 .checkentry = cgroup_mt_check_v1,
209 .match = cgroup_mt_v1,
210 .matchsize = sizeof(struct xt_cgroup_info_v1),
211 .usersize = offsetof(struct xt_cgroup_info_v1, priv),
212 .destroy = cgroup_mt_destroy_v1,
213 .me = THIS_MODULE,
214 .hooks = (1 << NF_INET_LOCAL_OUT) |
215 (1 << NF_INET_POST_ROUTING) |
216 (1 << NF_INET_LOCAL_IN),
217 },
218 {
219 .name = "cgroup",
220 .revision = 2,
221 .family = NFPROTO_UNSPEC,
222 .checkentry = cgroup_mt_check_v2,
223 .match = cgroup_mt_v2,
224 .matchsize = sizeof(struct xt_cgroup_info_v2),
225 .usersize = offsetof(struct xt_cgroup_info_v2, priv),
226 .destroy = cgroup_mt_destroy_v2,
227 .me = THIS_MODULE,
228 .hooks = (1 << NF_INET_LOCAL_OUT) |
229 (1 << NF_INET_POST_ROUTING) |
230 (1 << NF_INET_LOCAL_IN),
231 },
232};
233
234static int __init cgroup_mt_init(void)
235{
236 return xt_register_matches(cgroup_mt_reg, ARRAY_SIZE(cgroup_mt_reg));
237}
238
239static void __exit cgroup_mt_exit(void)
240{
241 xt_unregister_matches(cgroup_mt_reg, ARRAY_SIZE(cgroup_mt_reg));
242}
243
244module_init(cgroup_mt_init);
245module_exit(cgroup_mt_exit);