Initial import

1 files changed, 471 insertions, 0 deletions

diff --git a/security/selinux/xfrm.c b/security/selinux/xfrm.c
new file mode 100644
index 000000000..98b042630
--- /dev/null
+++ b/security/selinux/xfrm.c
@@ -0,0 +1,471 @@
+/*
+ *  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/netfilter.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter_ipv6.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 = iter->child) {
+			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);
+}