ethtool: Fix potential user buffer overflow for ETHTOOL_{G, S}RXFH

commit bf988435bd5b53529f4408a8efb1f433f6ddfda9 upstream.

struct ethtool_rxnfc was originally defined in 2.6.27 for the
ETHTOOL_{G,S}RXFH command with only the cmd, flow_type and data
fields.  It was then extended in 2.6.30 to support various additional
commands.  These commands should have been defined to use a new
structure, but it is too late to change that now.

Since user-space may still be using the old structure definition
for the ETHTOOL_{G,S}RXFH commands, and since they do not need the
additional fields, only copy the originally defined fields to and
from user-space.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 29 insertions, 9 deletions

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 2c21f7aef9a..5aef51eb3d1 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -216,22 +216,34 @@ static int ethtool_get_drvinfo(struct net_device *dev, void __user *useraddr)
 	return 0;
 }
 
-static int ethtool_set_rxnfc(struct net_device *dev, void __user *useraddr)
+static int ethtool_set_rxnfc(struct net_device *dev,
+			     u32 cmd, void __user *useraddr)
 {
-	struct ethtool_rxnfc cmd;
+	struct ethtool_rxnfc info;
+	size_t info_size = sizeof(info);
 
 	if (!dev->ethtool_ops->set_rxnfc)
 		return -EOPNOTSUPP;
 
-	if (copy_from_user(&cmd, useraddr, sizeof(cmd)))
+	/* struct ethtool_rxnfc was originally defined for
+	 * ETHTOOL_{G,S}RXFH with only the cmd, flow_type and data
+	 * members.  User-space might still be using that
+	 * definition. */
+	if (cmd == ETHTOOL_SRXFH)
+		info_size = (offsetof(struct ethtool_rxnfc, data) +
+			     sizeof(info.data));
+
+	if (copy_from_user(&info, useraddr, info_size))
 		return -EFAULT;
 
-	return dev->ethtool_ops->set_rxnfc(dev, &cmd);
+	return dev->ethtool_ops->set_rxnfc(dev, &info);
 }
 
-static int ethtool_get_rxnfc(struct net_device *dev, void __user *useraddr)
+static int ethtool_get_rxnfc(struct net_device *dev,
+			     u32 cmd, void __user *useraddr)
 {
 	struct ethtool_rxnfc info;
+	size_t info_size = sizeof(info);
 	const struct ethtool_ops *ops = dev->ethtool_ops;
 	int ret;
 	void *rule_buf = NULL;
@@ -239,7 +251,15 @@ static int ethtool_get_rxnfc(struct net_device *dev, void __user *useraddr)
 	if (!ops->get_rxnfc)
 		return -EOPNOTSUPP;
 
-	if (copy_from_user(&info, useraddr, sizeof(info)))
+	/* struct ethtool_rxnfc was originally defined for
+	 * ETHTOOL_{G,S}RXFH with only the cmd, flow_type and data
+	 * members.  User-space might still be using that
+	 * definition. */
+	if (cmd == ETHTOOL_GRXFH)
+		info_size = (offsetof(struct ethtool_rxnfc, data) +
+			     sizeof(info.data));
+
+	if (copy_from_user(&info, useraddr, info_size))
 		return -EFAULT;
 
 	if (info.cmd == ETHTOOL_GRXCLSRLALL) {
@@ -257,7 +277,7 @@ static int ethtool_get_rxnfc(struct net_device *dev, void __user *useraddr)
 		goto err_out;
 
 	ret = -EFAULT;
-	if (copy_to_user(useraddr, &info, sizeof(info)))
+	if (copy_to_user(useraddr, &info, info_size))
 		goto err_out;
 
 	if (rule_buf) {
@@ -1112,12 +1132,12 @@ int dev_ethtool(struct net *net, struct ifreq *ifr)
 	case ETHTOOL_GRXCLSRLCNT:
 	case ETHTOOL_GRXCLSRULE:
 	case ETHTOOL_GRXCLSRLALL:
-		rc = ethtool_get_rxnfc(dev, useraddr);
+		rc = ethtool_get_rxnfc(dev, ethcmd, useraddr);
 		break;
 	case ETHTOOL_SRXFH:
 	case ETHTOOL_SRXCLSRLDEL:
 	case ETHTOOL_SRXCLSRLINS:
-		rc = ethtool_set_rxnfc(dev, useraddr);
+		rc = ethtool_set_rxnfc(dev, ethcmd, useraddr);
 		break;
 	case ETHTOOL_GGRO:
 		rc = ethtool_get_gro(dev, useraddr);