smack_netfilter.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  Simplified MAC Kernel (smack) security module
 *
 *  This file contains the Smack netfilter implementation
 *
 *  Author:
 *	Casey Schaufler <casey@schaufler-ca.com>
 *
 *  Copyright (C) 2014 Casey Schaufler <casey@schaufler-ca.com>
 *  Copyright (C) 2014 Intel Corporation.
 */

#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv6.h>
#include <linux/netdevice.h>
#include <net/inet_sock.h>
#include <net/net_namespace.h>
#include "smack.h"

#if IS_ENABLED(CONFIG_IPV6)

static unsigned int smack_ipv6_output(void *priv,
					struct sk_buff *skb,
					const struct nf_hook_state *state)
{
	struct sock *sk = skb_to_full_sk(skb);
	struct socket_smack *ssp;
	struct smack_known *skp;

	if (sk && sk->sk_security) {
		ssp = sk->sk_security;
		skp = ssp->smk_out;
		skb->secmark = skp->smk_secid;
	}

	return NF_ACCEPT;
}
#endif	/* IPV6 */

static unsigned int smack_ipv4_output(void *priv,
					struct sk_buff *skb,
					const struct nf_hook_state *state)
{
	struct sock *sk = skb_to_full_sk(skb);
	struct socket_smack *ssp;
	struct smack_known *skp;

	if (sk && sk->sk_security) {
		ssp = sk->sk_security;
		skp = ssp->smk_out;
		skb->secmark = skp->smk_secid;
	}

	return NF_ACCEPT;
}

static const struct nf_hook_ops smack_nf_ops[] = {
	{
		.hook =		smack_ipv4_output,
		.pf =		NFPROTO_IPV4,
		.hooknum =	NF_INET_LOCAL_OUT,
		.priority =	NF_IP_PRI_SELINUX_FIRST,
	},
#if IS_ENABLED(CONFIG_IPV6)
	{
		.hook =		smack_ipv6_output,
		.pf =		NFPROTO_IPV6,
		.hooknum =	NF_INET_LOCAL_OUT,
		.priority =	NF_IP6_PRI_SELINUX_FIRST,
	},
#endif	/* IPV6 */
};

static int __net_init smack_nf_register(struct net *net)
{
	return nf_register_net_hooks(net, smack_nf_ops,
				     ARRAY_SIZE(smack_nf_ops));
}

static void __net_exit smack_nf_unregister(struct net *net)
{
	nf_unregister_net_hooks(net, smack_nf_ops, ARRAY_SIZE(smack_nf_ops));
}

static struct pernet_operations smack_net_ops = {
	.init = smack_nf_register,
	.exit = smack_nf_unregister,
};

static int __init smack_nf_ip_init(void)
{
	if (smack_enabled == 0)
		return 0;

	printk(KERN_DEBUG "Smack: Registering netfilter hooks\n");
	return register_pernet_subsys(&smack_net_ops);
}

__initcall(smack_nf_ip_init);