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// SPDX-License-Identifier: GPL-2.0-only
/*
* Xtables module to match the process control group.
*
* Might be used to implement individual "per-application" firewall
* policies in contrast to global policies based on control groups.
* Matching is based upon processes tagged to net_cls' classid marker.
*
* (C) 2013 Daniel Borkmann <dborkman@redhat.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/skbuff.h>
#include <linux/module.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_cgroup.h>
#include <net/sock.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
MODULE_DESCRIPTION("Xtables: process control group matching");
MODULE_ALIAS("ipt_cgroup");
MODULE_ALIAS("ip6t_cgroup");
static int cgroup_mt_check_v0(const struct xt_mtchk_param *par)
{
struct xt_cgroup_info_v0 *info = par->matchinfo;
if (info->invert & ~1)
return -EINVAL;
return 0;
}
static int cgroup_mt_check_v1(const struct xt_mtchk_param *par)
{
struct xt_cgroup_info_v1 *info = par->matchinfo;
struct cgroup *cgrp;
if ((info->invert_path & ~1) || (info->invert_classid & ~1))
return -EINVAL;
if (!info->has_path && !info->has_classid) {
pr_info("xt_cgroup: no path or classid specified\n");
return -EINVAL;
}
if (info->has_path && info->has_classid) {
pr_info_ratelimited("path and classid specified\n");
return -EINVAL;
}
info->priv = NULL;
if (info->has_path) {
cgrp = cgroup_get_from_path(info->path);
if (IS_ERR(cgrp)) {
pr_info_ratelimited("invalid path, errno=%ld\n",
PTR_ERR(cgrp));
return -EINVAL;
}
info->priv = cgrp;
}
return 0;
}
static int cgroup_mt_check_v2(const struct xt_mtchk_param *par)
{
struct xt_cgroup_info_v2 *info = par->matchinfo;
struct cgroup *cgrp;
if ((info->invert_path & ~1) || (info->invert_classid & ~1))
return -EINVAL;
if (!info->has_path && !info->has_classid) {
pr_info("xt_cgroup: no path or classid specified\n");
return -EINVAL;
}
if (info->has_path && info->has_classid) {
pr_info_ratelimited("path and classid specified\n");
return -EINVAL;
}
info->priv = NULL;
if (info->has_path) {
cgrp = cgroup_get_from_path(info->path);
if (IS_ERR(cgrp)) {
pr_info_ratelimited("invalid path, errno=%ld\n",
PTR_ERR(cgrp));
return -EINVAL;
}
info->priv = cgrp;
}
return 0;
}
static bool
cgroup_mt_v0(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_cgroup_info_v0 *info = par->matchinfo;
struct sock *sk = skb->sk;
if (!sk || !sk_fullsock(sk) || !net_eq(xt_net(par), sock_net(sk)))
return false;
return (info->id == sock_cgroup_classid(&skb->sk->sk_cgrp_data)) ^
info->invert;
}
static bool cgroup_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_cgroup_info_v1 *info = par->matchinfo;
struct sock_cgroup_data *skcd = &skb->sk->sk_cgrp_data;
struct cgroup *ancestor = info->priv;
struct sock *sk = skb->sk;
if (!sk || !sk_fullsock(sk) || !net_eq(xt_net(par), sock_net(sk)))
return false;
if (ancestor)
return cgroup_is_descendant(sock_cgroup_ptr(skcd), ancestor) ^
info->invert_path;
else
return (info->classid == sock_cgroup_classid(skcd)) ^
info->invert_classid;
}
static bool cgroup_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_cgroup_info_v2 *info = par->matchinfo;
struct sock_cgroup_data *skcd = &skb->sk->sk_cgrp_data;
struct cgroup *ancestor = info->priv;
struct sock *sk = skb->sk;
if (!sk || !sk_fullsock(sk) || !net_eq(xt_net(par), sock_net(sk)))
return false;
if (ancestor)
return cgroup_is_descendant(sock_cgroup_ptr(skcd), ancestor) ^
info->invert_path;
else
return (info->classid == sock_cgroup_classid(skcd)) ^
info->invert_classid;
}
static void cgroup_mt_destroy_v1(const struct xt_mtdtor_param *par)
{
struct xt_cgroup_info_v1 *info = par->matchinfo;
if (info->priv)
cgroup_put(info->priv);
}
static void cgroup_mt_destroy_v2(const struct xt_mtdtor_param *par)
{
struct xt_cgroup_info_v2 *info = par->matchinfo;
if (info->priv)
cgroup_put(info->priv);
}
static struct xt_match cgroup_mt_reg[] __read_mostly = {
{
.name = "cgroup",
.revision = 0,
.family = NFPROTO_UNSPEC,
.checkentry = cgroup_mt_check_v0,
.match = cgroup_mt_v0,
.matchsize = sizeof(struct xt_cgroup_info_v0),
.me = THIS_MODULE,
.hooks = (1 << NF_INET_LOCAL_OUT) |
(1 << NF_INET_POST_ROUTING) |
(1 << NF_INET_LOCAL_IN),
},
{
.name = "cgroup",
.revision = 1,
.family = NFPROTO_UNSPEC,
.checkentry = cgroup_mt_check_v1,
.match = cgroup_mt_v1,
.matchsize = sizeof(struct xt_cgroup_info_v1),
.usersize = offsetof(struct xt_cgroup_info_v1, priv),
.destroy = cgroup_mt_destroy_v1,
.me = THIS_MODULE,
.hooks = (1 << NF_INET_LOCAL_OUT) |
(1 << NF_INET_POST_ROUTING) |
(1 << NF_INET_LOCAL_IN),
},
{
.name = "cgroup",
.revision = 2,
.family = NFPROTO_UNSPEC,
.checkentry = cgroup_mt_check_v2,
.match = cgroup_mt_v2,
.matchsize = sizeof(struct xt_cgroup_info_v2),
.usersize = offsetof(struct xt_cgroup_info_v2, priv),
.destroy = cgroup_mt_destroy_v2,
.me = THIS_MODULE,
.hooks = (1 << NF_INET_LOCAL_OUT) |
(1 << NF_INET_POST_ROUTING) |
(1 << NF_INET_LOCAL_IN),
},
};
static int __init cgroup_mt_init(void)
{
return xt_register_matches(cgroup_mt_reg, ARRAY_SIZE(cgroup_mt_reg));
}
static void __exit cgroup_mt_exit(void)
{
xt_unregister_matches(cgroup_mt_reg, ARRAY_SIZE(cgroup_mt_reg));
}
module_init(cgroup_mt_init);
module_exit(cgroup_mt_exit);
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