Commit 266e8347 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by David S. Miller

macvlan: better mode validation

macvlan passthrough mode is special: it's not possible to switch to or
from it through a netlink command.

But if you try, the command will succeed, which is

Validate input and return error to user.

Cc:  Sridhar Samudrala <>
Cc: "David S. Miller" <>
Signed-off-by: default avatarMichael S. Tsirkin <>
Signed-off-by: default avatarDavid S. Miller <>
parent c756891a
......@@ -863,6 +863,18 @@ static int macvlan_changelink(struct net_device *dev,
struct nlattr *tb[], struct nlattr *data[])
struct macvlan_dev *vlan = netdev_priv(dev);
enum macvlan_mode mode;
bool set_mode = false;
/* Validate mode, but don't set yet: setting flags may fail. */
if (data && data[IFLA_MACVLAN_MODE]) {
set_mode = true;
mode = nla_get_u32(data[IFLA_MACVLAN_MODE]);
/* Passthrough mode can't be set or cleared dynamically */
if ((mode == MACVLAN_MODE_PASSTHRU) !=
(vlan->mode == MACVLAN_MODE_PASSTHRU))
return -EINVAL;
if (data && data[IFLA_MACVLAN_FLAGS]) {
__u16 flags = nla_get_u16(data[IFLA_MACVLAN_FLAGS]);
......@@ -879,8 +891,8 @@ static int macvlan_changelink(struct net_device *dev,
vlan->flags = flags;
if (data && data[IFLA_MACVLAN_MODE])
vlan->mode = nla_get_u32(data[IFLA_MACVLAN_MODE]);
if (set_mode)
vlan->mode = mode;
return 0;
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