net: socket: simplify dev_ifconf handling

The dev_ifconf() calling conventions make compat handling
more complicated than necessary, simplify this by moving
the in_compat_syscall() check into the function.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 29 insertions, 26 deletions

diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
index c22c3dc15ce9..950e2fe5d56a 100644
--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -31,48 +31,51 @@ static int dev_ifname(struct net *net, struct ifreq *ifr)
  *	size eventually, and there is nothing I can do about it.
  *	Thus we will need a 'compatibility mode'.
  */
-
-int dev_ifconf(struct net *net, struct ifconf *ifc, int size)
+int dev_ifconf(struct net *net, struct ifconf __user *uifc)
 {
 	struct net_device *dev;
-	char __user *pos;
-	int len;
-	int total;
-	int i;
+	void __user *pos;
+	size_t size;
+	int len, total = 0, done;
 
-	/*
-	 *	Fetch the caller's info block.
-	 */
+	/* both the ifconf and the ifreq structures are slightly different */
+	if (in_compat_syscall()) {
+		struct compat_ifconf ifc32;
+
+		if (copy_from_user(&ifc32, uifc, sizeof(struct compat_ifconf)))
+			return -EFAULT;
 
-	pos = ifc->ifc_buf;
-	len = ifc->ifc_len;
+		pos = compat_ptr(ifc32.ifcbuf);
+		len = ifc32.ifc_len;
+		size = sizeof(struct compat_ifreq);
+	} else {
+		struct ifconf ifc;
 
-	/*
-	 *	Loop over the interfaces, and write an info block for each.
-	 */
+		if (copy_from_user(&ifc, uifc, sizeof(struct ifconf)))
+			return -EFAULT;
 
-	total = 0;
+		pos = ifc.ifc_buf;
+		len = ifc.ifc_len;
+		size = sizeof(struct ifreq);
+	}
+
+	/* Loop over the interfaces, and write an info block for each. */
+	rtnl_lock();
 	for_each_netdev(net, dev) {
-		int done;
 		if (!pos)
 			done = inet_gifconf(dev, NULL, 0, size);
 		else
 			done = inet_gifconf(dev, pos + total,
 					    len - total, size);
-		if (done < 0)
+		if (done < 0) {
+			rtnl_unlock();
 			return -EFAULT;
+		}
 		total += done;
 	}
+	rtnl_unlock();
 
-	/*
-	 *	All done.  Write the updated control block back to the caller.
-	 */
-	ifc->ifc_len = total;
-
-	/*
-	 * 	Both BSD and Solaris return 0 here, so we do too.
-	 */
-	return 0;
+	return put_user(total, &uifc->ifc_len);
 }
 
 static int dev_getifmap(struct net_device *dev, struct ifreq *ifr)