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