commit 44e2b838c24d883dae8496dc7b6ddac7956ba53c
author Benedict Wong <benedictwong@google.com> Wed Jul 25 13:45:29 2018 -0700
committer Steffen Klassert <steffen.klassert@secunet.com> Thu Jul 26 07:17:26 2018 +0200
tree 7ce16ee0b9d72799f360d2269075784c1f1cbc50
parent 934ffce1343f22ed5e2d0bd6da4440f4848074de

xfrm: Return detailed errors from xfrmi_newlink

Currently all failure modes of xfrm interface creation return EEXIST.
This change improves the granularity of errnos provided by also
returning ENODEV or EINVAL if failures happen in looking up the
underlying interface, or a required parameter is not provided.

This change has been tested against the Android Kernel Networking Tests,
with additional xfrmi_newlink tests here:

https://android-review.googlesource.com/c/kernel/tests/+/715755

Signed-off-by: Benedict Wong <benedictwong@google.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/xfrm/xfrm_interface.c

diff --git a/net/xfrm/xfrm_interface.c b/net/xfrm/xfrm_interface.c
index ccfe18d..481d730 100644
--- a/net/xfrm/xfrm_interface.c
+++ b/net/xfrm/xfrm_interface.c
@@ -149,14 +149,18 @@ static struct xfrm_if *xfrmi_create(struct net *net, struct xfrm_if_parms *p)
 	char name[IFNAMSIZ];
 	int err;
 
-	if (p->name[0])
+	if (p->name[0]) {
 		strlcpy(name, p->name, IFNAMSIZ);
-	else
+	} else {
+		err = -EINVAL;
 		goto failed;
+	}
 
 	dev = alloc_netdev(sizeof(*xi), name, NET_NAME_UNKNOWN, xfrmi_dev_setup);
-	if (!dev)
+	if (!dev) {
+		err = -EAGAIN;
 		goto failed;
+	}
 
 	dev_net_set(dev, net);
 
@@ -165,8 +169,10 @@ static struct xfrm_if *xfrmi_create(struct net *net, struct xfrm_if_parms *p)
 	xi->net = net;
 	xi->dev = dev;
 	xi->phydev = dev_get_by_index(net, p->link);
-	if (!xi->phydev)
+	if (!xi->phydev) {
+		err = -ENODEV;
 		goto failed_free;
+	}
 
 	err = xfrmi_create2(dev);
 	if (err < 0)
@@ -179,7 +185,7 @@ static struct xfrm_if *xfrmi_create(struct net *net, struct xfrm_if_parms *p)
 failed_free:
 	free_netdev(dev);
 failed:
-	return NULL;
+	return ERR_PTR(err);
 }
 
 static struct xfrm_if *xfrmi_locate(struct net *net, struct xfrm_if_parms *p,
@@ -194,13 +200,13 @@ static struct xfrm_if *xfrmi_locate(struct net *net, struct xfrm_if_parms *p,
 	     xip = &xi->next) {
 		if (xi->p.if_id == p->if_id) {
 			if (create)
-				return NULL;
+				return ERR_PTR(-EEXIST);
 
 			return xi;
 		}
 	}
 	if (!create)
-		return NULL;
+		return ERR_PTR(-ENODEV);
 	return xfrmi_create(net, p);
 }
 
@@ -682,8 +688,9 @@ static int xfrmi_newlink(struct net *src_net, struct net_device *dev,
 
 	nla_strlcpy(p->name, tb[IFLA_IFNAME], IFNAMSIZ);
 
-	if (!xfrmi_locate(net, p, 1))
-		return -EEXIST;
+	xi = xfrmi_locate(net, p, 1);
+	if (IS_ERR(xi))
+		return PTR_ERR(xi);
 
 	return 0;
 }
@@ -704,11 +711,12 @@ static int xfrmi_changelink(struct net_device *dev, struct nlattr *tb[],
 
 	xi = xfrmi_locate(net, &xi->p, 0);
 
-	if (xi) {
+	if (IS_ERR_OR_NULL(xi)) {
+		xi = netdev_priv(dev);
+	} else {
 		if (xi->dev != dev)
 			return -EEXIST;
-	} else
-		xi = netdev_priv(dev);
+	}
 
 	return xfrmi_update(xi, &xi->p);
 }