LSM: Make the Labeled IPsec hooks more stack friendly

The xfrm_get_policy() and xfrm_add_pol_expire() put some rather large structs
on the stack to work around the LSM API.  This patch attempts to fix that
problem by changing the LSM API to require only the relevant "security"
pointers instead of the entire SPD entry; we do this for all of the
security_xfrm_policy*() functions to keep things consistent.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 43 insertions, 37 deletions

diff --git a/net/key/af_key.c b/net/key/af_key.c
index 6db5892..1fb0fe4 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -2292,7 +2292,7 @@ static int pfkey_spdadd(struct sock *sk, struct sk_buff *skb, struct sadb_msg *h
 			goto out;
 		}
 
-		err = security_xfrm_policy_alloc(xp, uctx);
+		err = security_xfrm_policy_alloc(&xp->security, uctx);
 		kfree(uctx);
 
 		if (err)
@@ -2352,10 +2352,11 @@ static int pfkey_spddelete(struct sock *sk, struct sk_buff *skb, struct sadb_msg
 	int err;
 	struct sadb_address *sa;
 	struct sadb_x_policy *pol;
-	struct xfrm_policy *xp, tmp;
+	struct xfrm_policy *xp;
 	struct xfrm_selector sel;
 	struct km_event c;
 	struct sadb_x_sec_ctx *sec_ctx;
+	struct xfrm_sec_ctx *pol_ctx;
 
 	if (!present_and_same_family(ext_hdrs[SADB_EXT_ADDRESS_SRC-1],
 				     ext_hdrs[SADB_EXT_ADDRESS_DST-1]) ||
@@ -2385,25 +2386,23 @@ static int pfkey_spddelete(struct sock *sk, struct sk_buff *skb, struct sadb_msg
 		sel.dport_mask = htons(0xffff);
 
 	sec_ctx = (struct sadb_x_sec_ctx *) ext_hdrs[SADB_X_EXT_SEC_CTX-1];
-	memset(&tmp, 0, sizeof(struct xfrm_policy));
-
 	if (sec_ctx != NULL) {
 		struct xfrm_user_sec_ctx *uctx = pfkey_sadb2xfrm_user_sec_ctx(sec_ctx);
 
 		if (!uctx)
 			return -ENOMEM;
 
-		err = security_xfrm_policy_alloc(&tmp, uctx);
+		err = security_xfrm_policy_alloc(&pol_ctx, uctx);
 		kfree(uctx);
-
 		if (err)
 			return err;
-	}
-
-	xp = xfrm_policy_bysel_ctx(XFRM_POLICY_TYPE_MAIN, pol->sadb_x_policy_dir-1,
-				   &sel, tmp.security, 1, &err);
-	security_xfrm_policy_free(&tmp);
+	} else
+		pol_ctx = NULL;
 
+	xp = xfrm_policy_bysel_ctx(XFRM_POLICY_TYPE_MAIN,
+				   pol->sadb_x_policy_dir - 1, &sel, pol_ctx,
+				   1, &err);
+	security_xfrm_policy_free(pol_ctx);
 	if (xp == NULL)
 		return -ENOENT;
 
@@ -3298,7 +3297,7 @@ static struct xfrm_policy *pfkey_compile_policy(struct sock *sk, int opt,
 		if ((*dir = verify_sec_ctx_len(p)))
 			goto out;
 		uctx = pfkey_sadb2xfrm_user_sec_ctx(sec_ctx);
-		*dir = security_xfrm_policy_alloc(xp, uctx);
+		*dir = security_xfrm_policy_alloc(&xp->security, uctx);
 		kfree(uctx);
 
 		if (*dir)
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 15d73e4..ab4d0e5 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -263,7 +263,7 @@ void xfrm_policy_destroy(struct xfrm_policy *policy)
 	list_del(&policy->bytype);
 	write_unlock_bh(&xfrm_policy_lock);
 
-	security_xfrm_policy_free(policy);
+	security_xfrm_policy_free(policy->security);
 	kfree(policy);
 }
 EXPORT_SYMBOL(xfrm_policy_destroy);
@@ -676,7 +676,8 @@ struct xfrm_policy *xfrm_policy_bysel_ctx(u8 type, int dir,
 		    xfrm_sec_ctx_match(ctx, pol->security)) {
 			xfrm_pol_hold(pol);
 			if (delete) {
-				*err = security_xfrm_policy_delete(pol);
+				*err = security_xfrm_policy_delete(
+								pol->security);
 				if (*err) {
 					write_unlock_bh(&xfrm_policy_lock);
 					return pol;
@@ -718,7 +719,8 @@ struct xfrm_policy *xfrm_policy_byid(u8 type, int dir, u32 id, int delete,
 		if (pol->type == type && pol->index == id) {
 			xfrm_pol_hold(pol);
 			if (delete) {
-				*err = security_xfrm_policy_delete(pol);
+				*err = security_xfrm_policy_delete(
+								pol->security);
 				if (*err) {
 					write_unlock_bh(&xfrm_policy_lock);
 					return pol;
@@ -756,7 +758,7 @@ xfrm_policy_flush_secctx_check(u8 type, struct xfrm_audit *audit_info)
 				     &xfrm_policy_inexact[dir], bydst) {
 			if (pol->type != type)
 				continue;
-			err = security_xfrm_policy_delete(pol);
+			err = security_xfrm_policy_delete(pol->security);
 			if (err) {
 				xfrm_audit_policy_delete(pol, 0,
 							 audit_info->loginuid,
@@ -770,7 +772,8 @@ xfrm_policy_flush_secctx_check(u8 type, struct xfrm_audit *audit_info)
 					     bydst) {
 				if (pol->type != type)
 					continue;
-				err = security_xfrm_policy_delete(pol);
+				err = security_xfrm_policy_delete(
+								pol->security);
 				if (err) {
 					xfrm_audit_policy_delete(pol, 0,
 							audit_info->loginuid,
@@ -931,7 +934,8 @@ static int xfrm_policy_match(struct xfrm_policy *pol, struct flowi *fl,
 
 	match = xfrm_selector_match(sel, fl, family);
 	if (match)
-		ret = security_xfrm_policy_lookup(pol, fl->secid, dir);
+		ret = security_xfrm_policy_lookup(pol->security, fl->secid,
+						  dir);
 
 	return ret;
 }
@@ -1048,8 +1052,9 @@ static struct xfrm_policy *xfrm_sk_policy_lookup(struct sock *sk, int dir, struc
 		int err = 0;
 
 		if (match) {
-			err = security_xfrm_policy_lookup(pol, fl->secid,
-					policy_to_flow_dir(dir));
+			err = security_xfrm_policy_lookup(pol->security,
+						      fl->secid,
+						      policy_to_flow_dir(dir));
 			if (!err)
 				xfrm_pol_hold(pol);
 			else if (err == -ESRCH)
@@ -1138,7 +1143,8 @@ static struct xfrm_policy *clone_policy(struct xfrm_policy *old, int dir)
 
 	if (newp) {
 		newp->selector = old->selector;
-		if (security_xfrm_policy_clone(old, newp)) {
+		if (security_xfrm_policy_clone(old->security,
+					       &newp->security)) {
 			kfree(newp);
 			return NULL;  /* ENOMEM */
 		}
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 5578c90..ecf9d67 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -959,7 +959,7 @@ static int copy_from_user_sec_ctx(struct xfrm_policy *pol, struct nlattr **attrs
 		return 0;
 
 	uctx = nla_data(rt);
-	return security_xfrm_policy_alloc(pol, uctx);
+	return security_xfrm_policy_alloc(&pol->security, uctx);
 }
 
 static void copy_templates(struct xfrm_policy *xp, struct xfrm_user_tmpl *ut,
@@ -1143,7 +1143,7 @@ static int xfrm_add_policy(struct sk_buff *skb, struct nlmsghdr *nlh,
 			      NETLINK_CB(skb).sid);
 
 	if (err) {
-		security_xfrm_policy_free(xp);
+		security_xfrm_policy_free(xp->security);
 		kfree(xp);
 		return err;
 	}
@@ -1337,22 +1337,23 @@ static int xfrm_get_policy(struct sk_buff *skb, struct nlmsghdr *nlh,
 		xp = xfrm_policy_byid(type, p->dir, p->index, delete, &err);
 	else {
 		struct nlattr *rt = attrs[XFRMA_SEC_CTX];
-		struct xfrm_policy tmp;
+		struct xfrm_sec_ctx *ctx;
 
 		err = verify_sec_ctx_len(attrs);
 		if (err)
 			return err;
 
-		memset(&tmp, 0, sizeof(struct xfrm_policy));
 		if (rt) {
 			struct xfrm_user_sec_ctx *uctx = nla_data(rt);
 
-			if ((err = security_xfrm_policy_alloc(&tmp, uctx)))
+			err = security_xfrm_policy_alloc(&ctx, uctx);
+			if (err)
 				return err;
-		}
-		xp = xfrm_policy_bysel_ctx(type, p->dir, &p->sel, tmp.security,
+		} else
+			ctx = NULL;
+		xp = xfrm_policy_bysel_ctx(type, p->dir, &p->sel, ctx,
 					   delete, &err);
-		security_xfrm_policy_free(&tmp);
+		security_xfrm_policy_free(ctx);
 	}
 	if (xp == NULL)
 		return -ENOENT;
@@ -1572,26 +1573,26 @@ static int xfrm_add_pol_expire(struct sk_buff *skb, struct nlmsghdr *nlh,
 		xp = xfrm_policy_byid(type, p->dir, p->index, 0, &err);
 	else {
 		struct nlattr *rt = attrs[XFRMA_SEC_CTX];
-		struct xfrm_policy tmp;
+		struct xfrm_sec_ctx *ctx;
 
 		err = verify_sec_ctx_len(attrs);
 		if (err)
 			return err;
 
-		memset(&tmp, 0, sizeof(struct xfrm_policy));
 		if (rt) {
 			struct xfrm_user_sec_ctx *uctx = nla_data(rt);
 
-			if ((err = security_xfrm_policy_alloc(&tmp, uctx)))
+			err = security_xfrm_policy_alloc(&ctx, uctx);
+			if (err)
 				return err;
-		}
-		xp = xfrm_policy_bysel_ctx(type, p->dir, &p->sel, tmp.security,
-					   0, &err);
-		security_xfrm_policy_free(&tmp);
+		} else
+			ctx = NULL;
+		xp = xfrm_policy_bysel_ctx(type, p->dir, &p->sel, ctx, 0, &err);
+		security_xfrm_policy_free(ctx);
 	}
-
 	if (xp == NULL)
 		return -ENOENT;
+
 	read_lock(&xp->lock);
 	if (xp->dead) {
 		read_unlock(&xp->lock);