security/selinux/xfrm.c - kernel/msm-5.4 - Gitiles

 /*
  *  NSA Security-Enhanced Linux (SELinux) security module
  *
  *  This file contains the SELinux XFRM hook function implementations.
  *
  *  Authors:  Serge Hallyn <sergeh@us.ibm.com>
  *	      Trent Jaeger <jaegert@us.ibm.com>
  *
  *  Updated: Venkat Yekkirala <vyekkirala@TrustedCS.com>
  *
  *           Granular IPSec Associations for use in MLS environments.
  *
  *  Copyright (C) 2005 International Business Machines Corporation
  *  Copyright (C) 2006 Trusted Computer Solutions, Inc.
  *
  *	This program is free software; you can redistribute it and/or modify
  *	it under the terms of the GNU General Public License version 2,
  *	as published by the Free Software Foundation.
  */

 /*
  * USAGE:
  * NOTES:
  *   1. Make sure to enable the following options in your kernel config:
  *	CONFIG_SECURITY=y
  *	CONFIG_SECURITY_NETWORK=y
  *	CONFIG_SECURITY_NETWORK_XFRM=y
  *	CONFIG_SECURITY_SELINUX=m/y
  * ISSUES:
  *   1. Caching packets, so they are not dropped during negotiation
  *   2. Emulating a reasonable SO_PEERSEC across machines
  *   3. Testing addition of sk_policy's with security context via setsockopt
  */
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/security.h>
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/ip.h>
 #include <linux/tcp.h>
 #include <linux/skbuff.h>
 #include <linux/xfrm.h>
 #include <net/xfrm.h>
 #include <net/checksum.h>
 #include <net/udp.h>
 #include <linux/atomic.h>

 #include "avc.h"
 #include "objsec.h"
 #include "xfrm.h"

 /* Labeled XFRM instance counter */
 atomic_t selinux_xfrm_refcount = ATOMIC_INIT(0);

 /*
  * Returns true if the context is an LSM/SELinux context.
  */
 static inline int selinux_authorizable_ctx(struct xfrm_sec_ctx *ctx)
 {
 	return (ctx &&
 		(ctx->ctx_doi == XFRM_SC_DOI_LSM) &&
 		(ctx->ctx_alg == XFRM_SC_ALG_SELINUX));
 }

 /*
  * Returns true if the xfrm contains a security blob for SELinux.
  */
 static inline int selinux_authorizable_xfrm(struct xfrm_state *x)
 {
 	return selinux_authorizable_ctx(x->security);
 }

 /*
  * Allocates a xfrm_sec_state and populates it using the supplied security
  * xfrm_user_sec_ctx context.
  */
 static int selinux_xfrm_alloc_user(struct xfrm_sec_ctx **ctxp,
 				   struct xfrm_user_sec_ctx *uctx,
 				   gfp_t gfp)
 {
 	int rc;
 	const struct task_security_struct *tsec = current_security();
 	struct xfrm_sec_ctx *ctx = NULL;
 	u32 str_len;

 	if (ctxp == NULL || uctx == NULL ||
 	    uctx->ctx_doi != XFRM_SC_DOI_LSM ||
 	    uctx->ctx_alg != XFRM_SC_ALG_SELINUX)
 		return -EINVAL;

 	str_len = uctx->ctx_len;
 	if (str_len >= PAGE_SIZE)
 		return -ENOMEM;

 	ctx = kmalloc(sizeof(*ctx) + str_len + 1, gfp);
 	if (!ctx)
 		return -ENOMEM;

 	ctx->ctx_doi = XFRM_SC_DOI_LSM;
 	ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
 	ctx->ctx_len = str_len;
 	memcpy(ctx->ctx_str, &uctx[1], str_len);
 	ctx->ctx_str[str_len] = '\0';
 	rc = security_context_to_sid(ctx->ctx_str, str_len, &ctx->ctx_sid, gfp);
 	if (rc)
 		goto err;

 	rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
 			  SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT, NULL);
 	if (rc)
 		goto err;

 	*ctxp = ctx;
 	atomic_inc(&selinux_xfrm_refcount);
 	return 0;

 err:
 	kfree(ctx);
 	return rc;
 }

 /*
  * Free the xfrm_sec_ctx structure.
  */
 static void selinux_xfrm_free(struct xfrm_sec_ctx *ctx)
 {
 	if (!ctx)
 		return;

 	atomic_dec(&selinux_xfrm_refcount);
 	kfree(ctx);
 }

 /*
  * Authorize the deletion of a labeled SA or policy rule.
  */
 static int selinux_xfrm_delete(struct xfrm_sec_ctx *ctx)
 {
 	const struct task_security_struct *tsec = current_security();

 	if (!ctx)
 		return 0;

 	return avc_has_perm(tsec->sid, ctx->ctx_sid,
 			    SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT,
 			    NULL);
 }

 /*
  * LSM hook implementation that authorizes that a flow can use a xfrm policy
  * rule.
  */
 int selinux_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx, u32 fl_secid, u8 dir)
 {
 	int rc;

 	/* All flows should be treated as polmatch'ing an otherwise applicable
 	 * "non-labeled" policy. This would prevent inadvertent "leaks". */
 	if (!ctx)
 		return 0;

 	/* Context sid is either set to label or ANY_ASSOC */
 	if (!selinux_authorizable_ctx(ctx))
 		return -EINVAL;

 	rc = avc_has_perm(fl_secid, ctx->ctx_sid,
 			  SECCLASS_ASSOCIATION, ASSOCIATION__POLMATCH, NULL);
 	return (rc == -EACCES ? -ESRCH : rc);
 }

 /*
  * LSM hook implementation that authorizes that a state matches
  * the given policy, flow combo.
  */
 int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x,
 				      struct xfrm_policy *xp,
 				      const struct flowi *fl)
 {
 	u32 state_sid;

 	if (!xp->security)
 		if (x->security)
 			/* unlabeled policy and labeled SA can't match */
 			return 0;
 		else
 			/* unlabeled policy and unlabeled SA match all flows */
 			return 1;
 	else
 		if (!x->security)
 			/* unlabeled SA and labeled policy can't match */
 			return 0;
 		else
 			if (!selinux_authorizable_xfrm(x))
 				/* Not a SELinux-labeled SA */
 				return 0;

 	state_sid = x->security->ctx_sid;

 	if (fl->flowi_secid != state_sid)
 		return 0;

 	/* We don't need a separate SA Vs. policy polmatch check since the SA
 	 * is now of the same label as the flow and a flow Vs. policy polmatch
 	 * check had already happened in selinux_xfrm_policy_lookup() above. */
 	return (avc_has_perm(fl->flowi_secid, state_sid,
 			    SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO,
 			    NULL) ? 0 : 1);
 }

 static u32 selinux_xfrm_skb_sid_egress(struct sk_buff *skb)
 {
 	struct dst_entry *dst = skb_dst(skb);
 	struct xfrm_state *x;

 	if (dst == NULL)
 		return SECSID_NULL;
 	x = dst->xfrm;
 	if (x == NULL || !selinux_authorizable_xfrm(x))
 		return SECSID_NULL;

 	return x->security->ctx_sid;
 }

 static int selinux_xfrm_skb_sid_ingress(struct sk_buff *skb,
 					u32 *sid, int ckall)
 {
 	u32 sid_session = SECSID_NULL;
 	struct sec_path *sp = skb->sp;

 	if (sp) {
 		int i;

 		for (i = sp->len - 1; i >= 0; i--) {
 			struct xfrm_state *x = sp->xvec[i];
 			if (selinux_authorizable_xfrm(x)) {
 				struct xfrm_sec_ctx *ctx = x->security;

 				if (sid_session == SECSID_NULL) {
 					sid_session = ctx->ctx_sid;
 					if (!ckall)
 						goto out;
 				} else if (sid_session != ctx->ctx_sid) {
 					*sid = SECSID_NULL;
 					return -EINVAL;
 				}
 			}
 		}
 	}

 out:
 	*sid = sid_session;
 	return 0;
 }

 /*
  * LSM hook implementation that checks and/or returns the xfrm sid for the
  * incoming packet.
  */
 int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall)
 {
 	if (skb == NULL) {
 		*sid = SECSID_NULL;
 		return 0;
 	}
 	return selinux_xfrm_skb_sid_ingress(skb, sid, ckall);
 }

 int selinux_xfrm_skb_sid(struct sk_buff *skb, u32 *sid)
 {
 	int rc;

 	rc = selinux_xfrm_skb_sid_ingress(skb, sid, 0);
 	if (rc == 0 && *sid == SECSID_NULL)
 		*sid = selinux_xfrm_skb_sid_egress(skb);

 	return rc;
 }

 /*
  * LSM hook implementation that allocs and transfers uctx spec to xfrm_policy.
  */
 int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp,
 			      struct xfrm_user_sec_ctx *uctx,
 			      gfp_t gfp)
 {
 	return selinux_xfrm_alloc_user(ctxp, uctx, gfp);
 }

 /*
  * LSM hook implementation that copies security data structure from old to new
  * for policy cloning.
  */
 int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx,
 			      struct xfrm_sec_ctx **new_ctxp)
 {
 	struct xfrm_sec_ctx *new_ctx;

 	if (!old_ctx)
 		return 0;

 	new_ctx = kmemdup(old_ctx, sizeof(*old_ctx) + old_ctx->ctx_len,
 			  GFP_ATOMIC);
 	if (!new_ctx)
 		return -ENOMEM;
 	atomic_inc(&selinux_xfrm_refcount);
 	*new_ctxp = new_ctx;

 	return 0;
 }

 /*
  * LSM hook implementation that frees xfrm_sec_ctx security information.
  */
 void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx)
 {
 	selinux_xfrm_free(ctx);
 }

 /*
  * LSM hook implementation that authorizes deletion of labeled policies.
  */
 int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx)
 {
 	return selinux_xfrm_delete(ctx);
 }

 /*
  * LSM hook implementation that allocates a xfrm_sec_state, populates it using
  * the supplied security context, and assigns it to the xfrm_state.
  */
 int selinux_xfrm_state_alloc(struct xfrm_state *x,
 			     struct xfrm_user_sec_ctx *uctx)
 {
 	return selinux_xfrm_alloc_user(&x->security, uctx, GFP_KERNEL);
 }

 /*
  * LSM hook implementation that allocates a xfrm_sec_state and populates based
  * on a secid.
  */
 int selinux_xfrm_state_alloc_acquire(struct xfrm_state *x,
 				     struct xfrm_sec_ctx *polsec, u32 secid)
 {
 	int rc;
 	struct xfrm_sec_ctx *ctx;
 	char *ctx_str = NULL;
 	int str_len;

 	if (!polsec)
 		return 0;

 	if (secid == 0)
 		return -EINVAL;

 	rc = security_sid_to_context(secid, &ctx_str, &str_len);
 	if (rc)
 		return rc;

 	ctx = kmalloc(sizeof(*ctx) + str_len, GFP_ATOMIC);
 	if (!ctx) {
 		rc = -ENOMEM;
 		goto out;
 	}

 	ctx->ctx_doi = XFRM_SC_DOI_LSM;
 	ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
 	ctx->ctx_sid = secid;
 	ctx->ctx_len = str_len;
 	memcpy(ctx->ctx_str, ctx_str, str_len);

 	x->security = ctx;
 	atomic_inc(&selinux_xfrm_refcount);
 out:
 	kfree(ctx_str);
 	return rc;
 }

 /*
  * LSM hook implementation that frees xfrm_state security information.
  */
 void selinux_xfrm_state_free(struct xfrm_state *x)
 {
 	selinux_xfrm_free(x->security);
 }

 /*
  * LSM hook implementation that authorizes deletion of labeled SAs.
  */
 int selinux_xfrm_state_delete(struct xfrm_state *x)
 {
 	return selinux_xfrm_delete(x->security);
 }

 /*
  * LSM hook that controls access to unlabelled packets.  If
  * a xfrm_state is authorizable (defined by macro) then it was
  * already authorized by the IPSec process.  If not, then
  * we need to check for unlabelled access since this may not have
  * gone thru the IPSec process.
  */
 int selinux_xfrm_sock_rcv_skb(u32 sk_sid, struct sk_buff *skb,
 			      struct common_audit_data *ad)
 {
 	int i;
 	struct sec_path *sp = skb->sp;
 	u32 peer_sid = SECINITSID_UNLABELED;

 	if (sp) {
 		for (i = 0; i < sp->len; i++) {
 			struct xfrm_state *x = sp->xvec[i];

 			if (x && selinux_authorizable_xfrm(x)) {
 				struct xfrm_sec_ctx *ctx = x->security;
 				peer_sid = ctx->ctx_sid;
 				break;
 			}
 		}
 	}

 	/* This check even when there's no association involved is intended,
 	 * according to Trent Jaeger, to make sure a process can't engage in
 	 * non-IPsec communication unless explicitly allowed by policy. */
 	return avc_has_perm(sk_sid, peer_sid,
 			    SECCLASS_ASSOCIATION, ASSOCIATION__RECVFROM, ad);
 }

 /*
  * POSTROUTE_LAST hook's XFRM processing:
  * If we have no security association, then we need to determine
  * whether the socket is allowed to send to an unlabelled destination.
  * If we do have a authorizable security association, then it has already been
  * checked in the selinux_xfrm_state_pol_flow_match hook above.
  */
 int selinux_xfrm_postroute_last(u32 sk_sid, struct sk_buff *skb,
 				struct common_audit_data *ad, u8 proto)
 {
 	struct dst_entry *dst;

 	switch (proto) {
 	case IPPROTO_AH:
 	case IPPROTO_ESP:
 	case IPPROTO_COMP:
 		/* We should have already seen this packet once before it
 		 * underwent xfrm(s). No need to subject it to the unlabeled
 		 * check. */
 		return 0;
 	default:
 		break;
 	}

 	dst = skb_dst(skb);
 	if (dst) {
 		struct dst_entry *iter;

 		for (iter = dst; iter != NULL; iter = xfrm_dst_child(iter)) {
 			struct xfrm_state *x = iter->xfrm;

 			if (x && selinux_authorizable_xfrm(x))
 				return 0;
 		}
 	}

 	/* This check even when there's no association involved is intended,
 	 * according to Trent Jaeger, to make sure a process can't engage in
 	 * non-IPsec communication unless explicitly allowed by policy. */
 	return avc_has_perm(sk_sid, SECINITSID_UNLABELED,
 			    SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO, ad);
 }
	/*
	* NSA Security-Enhanced Linux (SELinux) security module
	*
	* This file contains the SELinux XFRM hook function implementations.
	*
	* Authors: Serge Hallyn <sergeh@us.ibm.com>
	* Trent Jaeger <jaegert@us.ibm.com>
	*
	* Updated: Venkat Yekkirala <vyekkirala@TrustedCS.com>
	*
	* Granular IPSec Associations for use in MLS environments.
	*
	* Copyright (C) 2005 International Business Machines Corporation
	* Copyright (C) 2006 Trusted Computer Solutions, Inc.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2,
	* as published by the Free Software Foundation.
	*/

	/*
	* USAGE:
	* NOTES:
	* 1. Make sure to enable the following options in your kernel config:
	* CONFIG_SECURITY=y
	* CONFIG_SECURITY_NETWORK=y
	* CONFIG_SECURITY_NETWORK_XFRM=y
	* CONFIG_SECURITY_SELINUX=m/y
	* ISSUES:
	* 1. Caching packets, so they are not dropped during negotiation
	* 2. Emulating a reasonable SO_PEERSEC across machines
	* 3. Testing addition of sk_policy's with security context via setsockopt
	*/
	#include <linux/kernel.h>
	#include <linux/init.h>
	#include <linux/security.h>
	#include <linux/types.h>
	#include <linux/slab.h>
	#include <linux/ip.h>
	#include <linux/tcp.h>
	#include <linux/skbuff.h>
	#include <linux/xfrm.h>
	#include <net/xfrm.h>
	#include <net/checksum.h>
	#include <net/udp.h>
	#include <linux/atomic.h>

	#include "avc.h"
	#include "objsec.h"
	#include "xfrm.h"

	/* Labeled XFRM instance counter */
	atomic_t selinux_xfrm_refcount = ATOMIC_INIT(0);

	/*
	* Returns true if the context is an LSM/SELinux context.
	*/
	static inline int selinux_authorizable_ctx(struct xfrm_sec_ctx *ctx)
	{
	return (ctx &&
	(ctx->ctx_doi == XFRM_SC_DOI_LSM) &&
	(ctx->ctx_alg == XFRM_SC_ALG_SELINUX));
	}

	/*
	* Returns true if the xfrm contains a security blob for SELinux.
	*/
	static inline int selinux_authorizable_xfrm(struct xfrm_state *x)
	{
	return selinux_authorizable_ctx(x->security);
	}

	/*
	* Allocates a xfrm_sec_state and populates it using the supplied security
	* xfrm_user_sec_ctx context.
	*/
	static int selinux_xfrm_alloc_user(struct xfrm_sec_ctx **ctxp,
	struct xfrm_user_sec_ctx *uctx,
	gfp_t gfp)
	{
	int rc;
	const struct task_security_struct *tsec = current_security();
	struct xfrm_sec_ctx *ctx = NULL;
	u32 str_len;

	if (ctxp == NULL \|\| uctx == NULL \|\|
	uctx->ctx_doi != XFRM_SC_DOI_LSM \|\|
	uctx->ctx_alg != XFRM_SC_ALG_SELINUX)
	return -EINVAL;

	str_len = uctx->ctx_len;
	if (str_len >= PAGE_SIZE)
	return -ENOMEM;

	ctx = kmalloc(sizeof(*ctx) + str_len + 1, gfp);
	if (!ctx)
	return -ENOMEM;

	ctx->ctx_doi = XFRM_SC_DOI_LSM;
	ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
	ctx->ctx_len = str_len;
	memcpy(ctx->ctx_str, &uctx[1], str_len);
	ctx->ctx_str[str_len] = '\0';
	rc = security_context_to_sid(ctx->ctx_str, str_len, &ctx->ctx_sid, gfp);
	if (rc)
	goto err;

	rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
	SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT, NULL);
	if (rc)
	goto err;

	*ctxp = ctx;
	atomic_inc(&selinux_xfrm_refcount);
	return 0;

	err:
	kfree(ctx);
	return rc;
	}

	/*
	* Free the xfrm_sec_ctx structure.
	*/
	static void selinux_xfrm_free(struct xfrm_sec_ctx *ctx)
	{
	if (!ctx)
	return;

	atomic_dec(&selinux_xfrm_refcount);
	kfree(ctx);
	}

	/*
	* Authorize the deletion of a labeled SA or policy rule.
	*/
	static int selinux_xfrm_delete(struct xfrm_sec_ctx *ctx)
	{
	const struct task_security_struct *tsec = current_security();

	if (!ctx)
	return 0;

	return avc_has_perm(tsec->sid, ctx->ctx_sid,
	SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT,
	NULL);
	}

	/*
	* LSM hook implementation that authorizes that a flow can use a xfrm policy
	* rule.
	*/
	int selinux_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx, u32 fl_secid, u8 dir)
	{
	int rc;

	/* All flows should be treated as polmatch'ing an otherwise applicable
	* "non-labeled" policy. This would prevent inadvertent "leaks". */
	if (!ctx)
	return 0;

	/* Context sid is either set to label or ANY_ASSOC */
	if (!selinux_authorizable_ctx(ctx))
	return -EINVAL;

	rc = avc_has_perm(fl_secid, ctx->ctx_sid,
	SECCLASS_ASSOCIATION, ASSOCIATION__POLMATCH, NULL);
	return (rc == -EACCES ? -ESRCH : rc);
	}

	/*
	* LSM hook implementation that authorizes that a state matches
	* the given policy, flow combo.
	*/
	int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x,
	struct xfrm_policy *xp,
	const struct flowi *fl)
	{
	u32 state_sid;

	if (!xp->security)
	if (x->security)
	/* unlabeled policy and labeled SA can't match */
	return 0;
	else
	/* unlabeled policy and unlabeled SA match all flows */
	return 1;
	else
	if (!x->security)
	/* unlabeled SA and labeled policy can't match */
	return 0;
	else
	if (!selinux_authorizable_xfrm(x))
	/* Not a SELinux-labeled SA */
	return 0;

	state_sid = x->security->ctx_sid;

	if (fl->flowi_secid != state_sid)
	return 0;

	/* We don't need a separate SA Vs. policy polmatch check since the SA
	* is now of the same label as the flow and a flow Vs. policy polmatch
	* check had already happened in selinux_xfrm_policy_lookup() above. */
	return (avc_has_perm(fl->flowi_secid, state_sid,
	SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO,
	NULL) ? 0 : 1);
	}

	static u32 selinux_xfrm_skb_sid_egress(struct sk_buff *skb)
	{
	struct dst_entry *dst = skb_dst(skb);
	struct xfrm_state *x;

	if (dst == NULL)
	return SECSID_NULL;
	x = dst->xfrm;
	if (x == NULL \|\| !selinux_authorizable_xfrm(x))
	return SECSID_NULL;

	return x->security->ctx_sid;
	}

	static int selinux_xfrm_skb_sid_ingress(struct sk_buff *skb,
	u32 *sid, int ckall)
	{
	u32 sid_session = SECSID_NULL;
	struct sec_path *sp = skb->sp;

	if (sp) {
	int i;

	for (i = sp->len - 1; i >= 0; i--) {
	struct xfrm_state *x = sp->xvec[i];
	if (selinux_authorizable_xfrm(x)) {
	struct xfrm_sec_ctx *ctx = x->security;

	if (sid_session == SECSID_NULL) {
	sid_session = ctx->ctx_sid;
	if (!ckall)
	goto out;
	} else if (sid_session != ctx->ctx_sid) {
	*sid = SECSID_NULL;
	return -EINVAL;
	}
	}
	}
	}

	out:
	*sid = sid_session;
	return 0;
	}

	/*
	* LSM hook implementation that checks and/or returns the xfrm sid for the
	* incoming packet.
	*/
	int selinux_xfrm_decode_session(struct sk_buff skb, u32 sid, int ckall)
	{
	if (skb == NULL) {
	*sid = SECSID_NULL;
	return 0;
	}
	return selinux_xfrm_skb_sid_ingress(skb, sid, ckall);
	}

	int selinux_xfrm_skb_sid(struct sk_buff skb, u32 sid)
	{
	int rc;

	rc = selinux_xfrm_skb_sid_ingress(skb, sid, 0);
	if (rc == 0 && *sid == SECSID_NULL)
	*sid = selinux_xfrm_skb_sid_egress(skb);

	return rc;
	}

	/*
	* LSM hook implementation that allocs and transfers uctx spec to xfrm_policy.
	*/
	int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp,
	struct xfrm_user_sec_ctx *uctx,
	gfp_t gfp)
	{
	return selinux_xfrm_alloc_user(ctxp, uctx, gfp);
	}

	/*
	* LSM hook implementation that copies security data structure from old to new
	* for policy cloning.
	*/
	int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx,
	struct xfrm_sec_ctx **new_ctxp)
	{
	struct xfrm_sec_ctx *new_ctx;

	if (!old_ctx)
	return 0;

	new_ctx = kmemdup(old_ctx, sizeof(*old_ctx) + old_ctx->ctx_len,
	GFP_ATOMIC);
	if (!new_ctx)
	return -ENOMEM;
	atomic_inc(&selinux_xfrm_refcount);
	*new_ctxp = new_ctx;

	return 0;
	}

	/*
	* LSM hook implementation that frees xfrm_sec_ctx security information.
	*/
	void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx)
	{
	selinux_xfrm_free(ctx);
	}

	/*
	* LSM hook implementation that authorizes deletion of labeled policies.
	*/
	int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx)
	{
	return selinux_xfrm_delete(ctx);
	}

	/*
	* LSM hook implementation that allocates a xfrm_sec_state, populates it using
	* the supplied security context, and assigns it to the xfrm_state.
	*/
	int selinux_xfrm_state_alloc(struct xfrm_state *x,
	struct xfrm_user_sec_ctx *uctx)
	{
	return selinux_xfrm_alloc_user(&x->security, uctx, GFP_KERNEL);
	}

	/*
	* LSM hook implementation that allocates a xfrm_sec_state and populates based
	* on a secid.
	*/
	int selinux_xfrm_state_alloc_acquire(struct xfrm_state *x,
	struct xfrm_sec_ctx *polsec, u32 secid)
	{
	int rc;
	struct xfrm_sec_ctx *ctx;
	char *ctx_str = NULL;
	int str_len;

	if (!polsec)
	return 0;

	if (secid == 0)
	return -EINVAL;

	rc = security_sid_to_context(secid, &ctx_str, &str_len);
	if (rc)
	return rc;

	ctx = kmalloc(sizeof(*ctx) + str_len, GFP_ATOMIC);
	if (!ctx) {
	rc = -ENOMEM;
	goto out;
	}

	ctx->ctx_doi = XFRM_SC_DOI_LSM;
	ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
	ctx->ctx_sid = secid;
	ctx->ctx_len = str_len;
	memcpy(ctx->ctx_str, ctx_str, str_len);

	x->security = ctx;
	atomic_inc(&selinux_xfrm_refcount);
	out:
	kfree(ctx_str);
	return rc;
	}

	/*
	* LSM hook implementation that frees xfrm_state security information.
	*/
	void selinux_xfrm_state_free(struct xfrm_state *x)
	{
	selinux_xfrm_free(x->security);
	}

	/*
	* LSM hook implementation that authorizes deletion of labeled SAs.
	*/
	int selinux_xfrm_state_delete(struct xfrm_state *x)
	{
	return selinux_xfrm_delete(x->security);
	}

	/*
	* LSM hook that controls access to unlabelled packets. If
	* a xfrm_state is authorizable (defined by macro) then it was
	* already authorized by the IPSec process. If not, then
	* we need to check for unlabelled access since this may not have
	* gone thru the IPSec process.
	*/
	int selinux_xfrm_sock_rcv_skb(u32 sk_sid, struct sk_buff *skb,
	struct common_audit_data *ad)
	{
	int i;
	struct sec_path *sp = skb->sp;
	u32 peer_sid = SECINITSID_UNLABELED;

	if (sp) {
	for (i = 0; i < sp->len; i++) {
	struct xfrm_state *x = sp->xvec[i];

	if (x && selinux_authorizable_xfrm(x)) {
	struct xfrm_sec_ctx *ctx = x->security;
	peer_sid = ctx->ctx_sid;
	break;
	}
	}
	}

	/* This check even when there's no association involved is intended,
	* according to Trent Jaeger, to make sure a process can't engage in
	* non-IPsec communication unless explicitly allowed by policy. */
	return avc_has_perm(sk_sid, peer_sid,
	SECCLASS_ASSOCIATION, ASSOCIATION__RECVFROM, ad);
	}

	/*
	* POSTROUTE_LAST hook's XFRM processing:
	* If we have no security association, then we need to determine
	* whether the socket is allowed to send to an unlabelled destination.
	* If we do have a authorizable security association, then it has already been
	* checked in the selinux_xfrm_state_pol_flow_match hook above.
	*/
	int selinux_xfrm_postroute_last(u32 sk_sid, struct sk_buff *skb,
	struct common_audit_data *ad, u8 proto)
	{
	struct dst_entry *dst;

	switch (proto) {
	case IPPROTO_AH:
	case IPPROTO_ESP:
	case IPPROTO_COMP:
	/* We should have already seen this packet once before it
	* underwent xfrm(s). No need to subject it to the unlabeled
	* check. */
	return 0;
	default:
	break;
	}

	dst = skb_dst(skb);
	if (dst) {
	struct dst_entry *iter;

	for (iter = dst; iter != NULL; iter = xfrm_dst_child(iter)) {
	struct xfrm_state *x = iter->xfrm;

	if (x && selinux_authorizable_xfrm(x))
	return 0;
	}
	}

	/* This check even when there's no association involved is intended,
	* according to Trent Jaeger, to make sure a process can't engage in
	* non-IPsec communication unless explicitly allowed by policy. */
	return avc_has_perm(sk_sid, SECINITSID_UNLABELED,
	SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO, ad);
	}