1 files changed, 311 insertions, 0 deletions
diff --git a/security/selinux/xfrm.c b/security/selinux/xfrm.c
new file mode 100644
index 000000000000..c4d87d4dca7b
--- /dev/null
+++ b/security/selinux/xfrm.c
@@ -0,0 +1,311 @@
+/*
+ *  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>
+ *
+ *  Copyright (C) 2005 International Business Machines Corporation
+ *
+ *	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/config.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/security.h>
+#include <linux/types.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter_ipv6.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 <asm/semaphore.h>
+
+#include "avc.h"
+#include "objsec.h"
+#include "xfrm.h"
+
+
+/*
+ * Returns true if 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);
+}
+
+/*
+ * LSM hook implementation that authorizes that a socket can be used
+ * with the corresponding xfrm_sec_ctx and direction.
+ */
+int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 sk_sid, u8 dir)
+{
+	int rc = 0;
+	u32 sel_sid = SECINITSID_UNLABELED;
+	struct xfrm_sec_ctx *ctx;
+
+	/* Context sid is either set to label or ANY_ASSOC */
+	if ((ctx = xp->security)) {
+		if (!selinux_authorizable_ctx(ctx))
+			return -EINVAL;
+
+		sel_sid = ctx->ctx_sid;
+	}
+
+	rc = avc_has_perm(sk_sid, sel_sid, SECCLASS_ASSOCIATION,
+			  ((dir == FLOW_DIR_IN) ? ASSOCIATION__RECVFROM :
+			   ((dir == FLOW_DIR_OUT) ?  ASSOCIATION__SENDTO :
+			    (ASSOCIATION__SENDTO | ASSOCIATION__RECVFROM))),
+			  NULL);
+
+	return rc;
+}
+
+/*
+ * Security blob allocation for xfrm_policy and xfrm_state
+ * CTX does not have a meaningful value on input
+ */
+static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx **ctxp, struct xfrm_user_sec_ctx *uctx)
+{
+	int rc = 0;
+	struct task_security_struct *tsec = current->security;
+	struct xfrm_sec_ctx *ctx;
+
+	BUG_ON(!uctx);
+	BUG_ON(uctx->ctx_doi != XFRM_SC_ALG_SELINUX);
+
+	if (uctx->ctx_len >= PAGE_SIZE)
+		return -ENOMEM;
+
+	*ctxp = ctx = kmalloc(sizeof(*ctx) +
+			      uctx->ctx_len,
+			      GFP_KERNEL);
+
+	if (!ctx)
+		return -ENOMEM;
+
+	ctx->ctx_doi = uctx->ctx_doi;
+	ctx->ctx_len = uctx->ctx_len;
+	ctx->ctx_alg = uctx->ctx_alg;
+
+	memcpy(ctx->ctx_str,
+	       uctx+1,
+	       ctx->ctx_len);
+	rc = security_context_to_sid(ctx->ctx_str,
+				     ctx->ctx_len,
+				     &ctx->ctx_sid);
+
+	if (rc)
+		goto out;
+
+	/*
+	 * Does the subject have permission to set security or permission to
+	 * do the relabel?
+	 * Must be permitted to relabel from default socket type (process type)
+	 * to specified context
+	 */
+	rc = avc_has_perm(tsec->sid, tsec->sid,
+			  SECCLASS_ASSOCIATION,
+			  ASSOCIATION__RELABELFROM, NULL);
+	if (rc)
+		goto out;
+
+	rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
+			  SECCLASS_ASSOCIATION,
+			  ASSOCIATION__RELABELTO, NULL);
+	if (rc)
+		goto out;
+
+	return rc;
+
+out:
+	*ctxp = 0;
+	kfree(ctx);
+	return rc;
+}
+
+/*
+ * LSM hook implementation that allocs and transfers uctx spec to
+ * xfrm_policy.
+ */
+int selinux_xfrm_policy_alloc(struct xfrm_policy *xp, struct xfrm_user_sec_ctx *uctx)
+{
+	int err;
+
+	BUG_ON(!xp);
+
+	err = selinux_xfrm_sec_ctx_alloc(&xp->security, uctx);
+	return err;
+}
+
+
+/*
+ * LSM hook implementation that copies security data structure from old to
+ * new for policy cloning.
+ */
+int selinux_xfrm_policy_clone(struct xfrm_policy *old, struct xfrm_policy *new)
+{
+	struct xfrm_sec_ctx *old_ctx, *new_ctx;
+
+	old_ctx = old->security;
+
+	if (old_ctx) {
+		new_ctx = new->security = kmalloc(sizeof(*new_ctx) +
+						  old_ctx->ctx_len,
+						  GFP_KERNEL);
+
+		if (!new_ctx)
+			return -ENOMEM;
+
+		memcpy(new_ctx, old_ctx, sizeof(*new_ctx));
+		memcpy(new_ctx->ctx_str, old_ctx->ctx_str, new_ctx->ctx_len);
+	}
+	return 0;
+}
+
+/*
+ * LSM hook implementation that frees xfrm_policy security information.
+ */
+void selinux_xfrm_policy_free(struct xfrm_policy *xp)
+{
+	struct xfrm_sec_ctx *ctx = xp->security;
+	if (ctx)
+		kfree(ctx);
+}
+
+/*
+ * LSM hook implementation that allocs and transfers sec_ctx spec to
+ * xfrm_state.
+ */
+int selinux_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *uctx)
+{
+	int err;
+
+	BUG_ON(!x);
+
+	err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx);
+	return err;
+}
+
+/*
+ * LSM hook implementation that frees xfrm_state security information.
+ */
+void selinux_xfrm_state_free(struct xfrm_state *x)
+{
+	struct xfrm_sec_ctx *ctx = x->security;
+	if (ctx)
+		kfree(ctx);
+}
+
+/*
+ * 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 isec_sid, struct sk_buff *skb)
+{
+	int i, rc = 0;
+	struct sec_path *sp;
+
+	sp = skb->sp;
+
+	if (sp) {
+		/*
+		 * __xfrm_policy_check does not approve unless xfrm_policy_ok
+		 * says that spi's match for policy and the socket.
+		 *
+		 *  Only need to verify the existence of an authorizable sp.
+		 */
+		for (i = 0; i < sp->len; i++) {
+			struct xfrm_state *x = sp->x[i].xvec;
+
+			if (x && selinux_authorizable_xfrm(x))
+				goto accept;
+		}
+	}
+
+	/* check SELinux sock for unlabelled access */
+	rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION,
+			  ASSOCIATION__RECVFROM, NULL);
+	if (rc)
+		goto drop;
+
+accept:
+	return 0;
+
+drop:
+	return rc;
+}
+
+/*
+ * 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 xfrm_policy_lookup hook.
+ */
+int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb)
+{
+	struct dst_entry *dst;
+	int rc = 0;
+
+	dst = skb->dst;
+
+	if (dst) {
+		struct dst_entry *dst_test;
+
+		for (dst_test = dst; dst_test != 0;
+		     dst_test = dst_test->child) {
+			struct xfrm_state *x = dst_test->xfrm;
+
+			if (x && selinux_authorizable_xfrm(x))
+				goto accept;
+		}
+	}
+
+	rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION,
+			  ASSOCIATION__SENDTO, NULL);
+	if (rc)
+		goto drop;
+
+accept:
+	return NF_ACCEPT;
+
+drop:
+	return NF_DROP;
+}