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
20 MODULE_LICENSE("GPL");
21 MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
22 MODULE_DESCRIPTION("Xtables: process control group matching");
23 MODULE_ALIAS("ipt_cgroup");
24 MODULE_ALIAS("ip6t_cgroup");
25
cgroup_mt_check_v0(const struct xt_mtchk_param * par)26 static int cgroup_mt_check_v0(const struct xt_mtchk_param *par)
27 {
28 struct xt_cgroup_info_v0 *info = par->matchinfo;
29
30 if (info->invert & ~1)
31 return -EINVAL;
32
33 return 0;
34 }
35
cgroup_mt_check_v1(const struct xt_mtchk_param * par)36 static int cgroup_mt_check_v1(const struct xt_mtchk_param *par)
37 {
38 struct xt_cgroup_info_v1 *info = par->matchinfo;
39 struct cgroup *cgrp;
40
41 if ((info->invert_path & ~1) || (info->invert_classid & ~1))
42 return -EINVAL;
43
44 if (!info->has_path && !info->has_classid) {
45 pr_info("xt_cgroup: no path or classid specified\n");
46 return -EINVAL;
47 }
48
49 if (info->has_path && info->has_classid) {
50 pr_info_ratelimited("path and classid specified\n");
51 return -EINVAL;
52 }
53
54 info->priv = NULL;
55 if (info->has_path) {
56 cgrp = cgroup_get_from_path(info->path);
57 if (IS_ERR(cgrp)) {
58 pr_info_ratelimited("invalid path, errno=%ld\n",
59 PTR_ERR(cgrp));
60 return -EINVAL;
61 }
62 info->priv = cgrp;
63 }
64
65 return 0;
66 }
67
cgroup_mt_check_v2(const struct xt_mtchk_param * par)68 static int cgroup_mt_check_v2(const struct xt_mtchk_param *par)
69 {
70 struct xt_cgroup_info_v2 *info = par->matchinfo;
71 struct cgroup *cgrp;
72
73 if ((info->invert_path & ~1) || (info->invert_classid & ~1))
74 return -EINVAL;
75
76 if (!info->has_path && !info->has_classid) {
77 pr_info("xt_cgroup: no path or classid specified\n");
78 return -EINVAL;
79 }
80
81 if (info->has_path && info->has_classid) {
82 pr_info_ratelimited("path and classid specified\n");
83 return -EINVAL;
84 }
85
86 info->priv = NULL;
87 if (info->has_path) {
88 cgrp = cgroup_get_from_path(info->path);
89 if (IS_ERR(cgrp)) {
90 pr_info_ratelimited("invalid path, errno=%ld\n",
91 PTR_ERR(cgrp));
92 return -EINVAL;
93 }
94 info->priv = cgrp;
95 }
96
97 return 0;
98 }
99
100 static bool
cgroup_mt_v0(const struct sk_buff * skb,struct xt_action_param * par)101 cgroup_mt_v0(const struct sk_buff *skb, struct xt_action_param *par)
102 {
103 const struct xt_cgroup_info_v0 *info = par->matchinfo;
104 struct sock *sk = skb->sk;
105
106 if (!sk || !sk_fullsock(sk) || !net_eq(xt_net(par), sock_net(sk)))
107 return false;
108
109 return (info->id == sock_cgroup_classid(&skb->sk->sk_cgrp_data)) ^
110 info->invert;
111 }
112
cgroup_mt_v1(const struct sk_buff * skb,struct xt_action_param * par)113 static bool cgroup_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
114 {
115 const struct xt_cgroup_info_v1 *info = par->matchinfo;
116 struct sock_cgroup_data *skcd = &skb->sk->sk_cgrp_data;
117 struct cgroup *ancestor = info->priv;
118 struct sock *sk = skb->sk;
119
120 if (!sk || !sk_fullsock(sk) || !net_eq(xt_net(par), sock_net(sk)))
121 return false;
122
123 if (ancestor)
124 return cgroup_is_descendant(sock_cgroup_ptr(skcd), ancestor) ^
125 info->invert_path;
126 else
127 return (info->classid == sock_cgroup_classid(skcd)) ^
128 info->invert_classid;
129 }
130
cgroup_mt_v2(const struct sk_buff * skb,struct xt_action_param * par)131 static bool cgroup_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
132 {
133 const struct xt_cgroup_info_v2 *info = par->matchinfo;
134 struct sock_cgroup_data *skcd = &skb->sk->sk_cgrp_data;
135 struct cgroup *ancestor = info->priv;
136 struct sock *sk = skb->sk;
137
138 if (!sk || !sk_fullsock(sk) || !net_eq(xt_net(par), sock_net(sk)))
139 return false;
140
141 if (ancestor)
142 return cgroup_is_descendant(sock_cgroup_ptr(skcd), ancestor) ^
143 info->invert_path;
144 else
145 return (info->classid == sock_cgroup_classid(skcd)) ^
146 info->invert_classid;
147 }
148
cgroup_mt_destroy_v1(const struct xt_mtdtor_param * par)149 static void cgroup_mt_destroy_v1(const struct xt_mtdtor_param *par)
150 {
151 struct xt_cgroup_info_v1 *info = par->matchinfo;
152
153 if (info->priv)
154 cgroup_put(info->priv);
155 }
156
cgroup_mt_destroy_v2(const struct xt_mtdtor_param * par)157 static void cgroup_mt_destroy_v2(const struct xt_mtdtor_param *par)
158 {
159 struct xt_cgroup_info_v2 *info = par->matchinfo;
160
161 if (info->priv)
162 cgroup_put(info->priv);
163 }
164
165 static struct xt_match cgroup_mt_reg[] __read_mostly = {
166 {
167 .name = "cgroup",
168 .revision = 0,
169 .family = NFPROTO_UNSPEC,
170 .checkentry = cgroup_mt_check_v0,
171 .match = cgroup_mt_v0,
172 .matchsize = sizeof(struct xt_cgroup_info_v0),
173 .me = THIS_MODULE,
174 .hooks = (1 << NF_INET_LOCAL_OUT) |
175 (1 << NF_INET_POST_ROUTING) |
176 (1 << NF_INET_LOCAL_IN),
177 },
178 {
179 .name = "cgroup",
180 .revision = 1,
181 .family = NFPROTO_UNSPEC,
182 .checkentry = cgroup_mt_check_v1,
183 .match = cgroup_mt_v1,
184 .matchsize = sizeof(struct xt_cgroup_info_v1),
185 .usersize = offsetof(struct xt_cgroup_info_v1, priv),
186 .destroy = cgroup_mt_destroy_v1,
187 .me = THIS_MODULE,
188 .hooks = (1 << NF_INET_LOCAL_OUT) |
189 (1 << NF_INET_POST_ROUTING) |
190 (1 << NF_INET_LOCAL_IN),
191 },
192 {
193 .name = "cgroup",
194 .revision = 2,
195 .family = NFPROTO_UNSPEC,
196 .checkentry = cgroup_mt_check_v2,
197 .match = cgroup_mt_v2,
198 .matchsize = sizeof(struct xt_cgroup_info_v2),
199 .usersize = offsetof(struct xt_cgroup_info_v2, priv),
200 .destroy = cgroup_mt_destroy_v2,
201 .me = THIS_MODULE,
202 .hooks = (1 << NF_INET_LOCAL_OUT) |
203 (1 << NF_INET_POST_ROUTING) |
204 (1 << NF_INET_LOCAL_IN),
205 },
206 };
207
cgroup_mt_init(void)208 static int __init cgroup_mt_init(void)
209 {
210 return xt_register_matches(cgroup_mt_reg, ARRAY_SIZE(cgroup_mt_reg));
211 }
212
cgroup_mt_exit(void)213 static void __exit cgroup_mt_exit(void)
214 {
215 xt_unregister_matches(cgroup_mt_reg, ARRAY_SIZE(cgroup_mt_reg));
216 }
217
218 module_init(cgroup_mt_init);
219 module_exit(cgroup_mt_exit);
220