Allow a network interface to be renamed when the interface
is up.
As described in the netconsole documentation [1], when netconsole is
used as a built-in, it will bring up the specified interface as soon as
possible. As a result, user space will not be able to rename the
interface since the kernel disallows renaming of interfaces that are
administratively up unless the 'IFF_LIVE_RENAME_OK' private flag was set
by the kernel.
The original solution [2] to this problem was to add a new parameter to
the netconsole configuration parameters that allows renaming of
the interface used by netconsole while it is administratively up.
However, during the discussion that followed, it became apparent that we
have no reason to keep the current restriction and instead we should
allow user space to rename interfaces regardless of their administrative
state:
1. The restriction was put in place over 20 years ago when renaming was
only possible via IOCTL and before rtnetlink started notifying user
space about such changes like it does today.
2. The 'IFF_LIVE_RENAME_OK' flag was added over 3 years ago in version
5.2 and no regressions were reported.
3. In-kernel listeners to 'NETDEV_CHANGENAME' do not seem to care about
the administrative state of interface.
Therefore, allow user space to rename running interfaces by removing the
restriction and the associated 'IFF_LIVE_RENAME_OK' flag. Help in
possible triage by emitting a message to the kernel log that an
interface was renamed while UP.
[1] https://www.kernel.org/doc/Documentation/networking/netconsole.rst
[2] https://lore.kernel.org/netdev/[email protected]/
Signed-off-by: Andy Ren <[email protected]>
---
Notes:
Changes from v1->v2
- Added placeholder comment in place of removed IFF_LIVE_RENAME_OK flag
- Added extra logging hints to indicate whether a network interface was
renamed while UP
Changes from v2->v3
- Patch description changes
include/linux/netdevice.h | 4 +---
net/core/dev.c | 19 ++-----------------
net/core/failover.c | 6 +++---
3 files changed, 6 insertions(+), 23 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index d45713a06568..4be87b89e481 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1650,7 +1650,6 @@ struct net_device_ops {
* @IFF_FAILOVER: device is a failover master device
* @IFF_FAILOVER_SLAVE: device is lower dev of a failover master device
* @IFF_L3MDEV_RX_HANDLER: only invoke the rx handler of L3 master device
- * @IFF_LIVE_RENAME_OK: rename is allowed while device is up and running
* @IFF_TX_SKB_NO_LINEAR: device/driver is capable of xmitting frames with
* skb_headlen(skb) == 0 (data starts from frag0)
* @IFF_CHANGE_PROTO_DOWN: device supports setting carrier via IFLA_PROTO_DOWN
@@ -1686,7 +1685,7 @@ enum netdev_priv_flags {
IFF_FAILOVER = 1<<27,
IFF_FAILOVER_SLAVE = 1<<28,
IFF_L3MDEV_RX_HANDLER = 1<<29,
- IFF_LIVE_RENAME_OK = 1<<30,
+ /* was IFF_LIVE_RENAME_OK */
IFF_TX_SKB_NO_LINEAR = BIT_ULL(31),
IFF_CHANGE_PROTO_DOWN = BIT_ULL(32),
};
@@ -1721,7 +1720,6 @@ enum netdev_priv_flags {
#define IFF_FAILOVER IFF_FAILOVER
#define IFF_FAILOVER_SLAVE IFF_FAILOVER_SLAVE
#define IFF_L3MDEV_RX_HANDLER IFF_L3MDEV_RX_HANDLER
-#define IFF_LIVE_RENAME_OK IFF_LIVE_RENAME_OK
#define IFF_TX_SKB_NO_LINEAR IFF_TX_SKB_NO_LINEAR
/* Specifies the type of the struct net_device::ml_priv pointer */
diff --git a/net/core/dev.c b/net/core/dev.c
index 3bacee3bee78..707de6b841d0 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1163,22 +1163,6 @@ int dev_change_name(struct net_device *dev, const char *newname)
net = dev_net(dev);
- /* Some auto-enslaved devices e.g. failover slaves are
- * special, as userspace might rename the device after
- * the interface had been brought up and running since
- * the point kernel initiated auto-enslavement. Allow
- * live name change even when these slave devices are
- * up and running.
- *
- * Typically, users of these auto-enslaving devices
- * don't actually care about slave name change, as
- * they are supposed to operate on master interface
- * directly.
- */
- if (dev->flags & IFF_UP &&
- likely(!(dev->priv_flags & IFF_LIVE_RENAME_OK)))
- return -EBUSY;
-
down_write(&devnet_rename_sem);
if (strncmp(newname, dev->name, IFNAMSIZ) == 0) {
@@ -1195,7 +1179,8 @@ int dev_change_name(struct net_device *dev, const char *newname)
}
if (oldname[0] && !strchr(oldname, '%'))
- netdev_info(dev, "renamed from %s\n", oldname);
+ netdev_info(dev, "renamed from %s%s\n", oldname,
+ dev->flags & IFF_UP ? " (while UP)" : "");
old_assign_type = dev->name_assign_type;
dev->name_assign_type = NET_NAME_RENAMED;
diff --git a/net/core/failover.c b/net/core/failover.c
index 864d2d83eff4..655411c4ca51 100644
--- a/net/core/failover.c
+++ b/net/core/failover.c
@@ -80,14 +80,14 @@ static int failover_slave_register(struct net_device *slave_dev)
goto err_upper_link;
}
- slave_dev->priv_flags |= (IFF_FAILOVER_SLAVE | IFF_LIVE_RENAME_OK);
+ slave_dev->priv_flags |= IFF_FAILOVER_SLAVE;
if (fops && fops->slave_register &&
!fops->slave_register(slave_dev, failover_dev))
return NOTIFY_OK;
netdev_upper_dev_unlink(slave_dev, failover_dev);
- slave_dev->priv_flags &= ~(IFF_FAILOVER_SLAVE | IFF_LIVE_RENAME_OK);
+ slave_dev->priv_flags &= ~IFF_FAILOVER_SLAVE;
err_upper_link:
netdev_rx_handler_unregister(slave_dev);
done:
@@ -121,7 +121,7 @@ int failover_slave_unregister(struct net_device *slave_dev)
netdev_rx_handler_unregister(slave_dev);
netdev_upper_dev_unlink(slave_dev, failover_dev);
- slave_dev->priv_flags &= ~(IFF_FAILOVER_SLAVE | IFF_LIVE_RENAME_OK);
+ slave_dev->priv_flags &= ~IFF_FAILOVER_SLAVE;
if (fops && fops->slave_unregister &&
!fops->slave_unregister(slave_dev, failover_dev))
--
2.38.1
On Mon, Nov 07, 2022 at 09:42:42AM -0800, Andy Ren wrote:
> Allow a network interface to be renamed when the interface
> is up.
>
> As described in the netconsole documentation [1], when netconsole is
> used as a built-in, it will bring up the specified interface as soon as
> possible. As a result, user space will not be able to rename the
> interface since the kernel disallows renaming of interfaces that are
> administratively up unless the 'IFF_LIVE_RENAME_OK' private flag was set
> by the kernel.
>
> The original solution [2] to this problem was to add a new parameter to
> the netconsole configuration parameters that allows renaming of
> the interface used by netconsole while it is administratively up.
> However, during the discussion that followed, it became apparent that we
> have no reason to keep the current restriction and instead we should
> allow user space to rename interfaces regardless of their administrative
> state:
>
> 1. The restriction was put in place over 20 years ago when renaming was
> only possible via IOCTL and before rtnetlink started notifying user
> space about such changes like it does today.
>
> 2. The 'IFF_LIVE_RENAME_OK' flag was added over 3 years ago in version
> 5.2 and no regressions were reported.
>
> 3. In-kernel listeners to 'NETDEV_CHANGENAME' do not seem to care about
> the administrative state of interface.
>
> Therefore, allow user space to rename running interfaces by removing the
> restriction and the associated 'IFF_LIVE_RENAME_OK' flag. Help in
> possible triage by emitting a message to the kernel log that an
> interface was renamed while UP.
>
> [1] https://www.kernel.org/doc/Documentation/networking/netconsole.rst
> [2] https://lore.kernel.org/netdev/[email protected]/
>
> Signed-off-by: Andy Ren <[email protected]>
Reviewed-by: Ido Schimmel <[email protected]>
On 11/7/22 10:42 AM, Andy Ren wrote:
> Allow a network interface to be renamed when the interface
> is up.
>
> As described in the netconsole documentation [1], when netconsole is
> used as a built-in, it will bring up the specified interface as soon as
> possible. As a result, user space will not be able to rename the
> interface since the kernel disallows renaming of interfaces that are
> administratively up unless the 'IFF_LIVE_RENAME_OK' private flag was set
> by the kernel.
>
> The original solution [2] to this problem was to add a new parameter to
> the netconsole configuration parameters that allows renaming of
> the interface used by netconsole while it is administratively up.
> However, during the discussion that followed, it became apparent that we
> have no reason to keep the current restriction and instead we should
> allow user space to rename interfaces regardless of their administrative
> state:
>
> 1. The restriction was put in place over 20 years ago when renaming was
> only possible via IOCTL and before rtnetlink started notifying user
> space about such changes like it does today.
>
> 2. The 'IFF_LIVE_RENAME_OK' flag was added over 3 years ago in version
> 5.2 and no regressions were reported.
>
> 3. In-kernel listeners to 'NETDEV_CHANGENAME' do not seem to care about
> the administrative state of interface.
>
> Therefore, allow user space to rename running interfaces by removing the
> restriction and the associated 'IFF_LIVE_RENAME_OK' flag. Help in
> possible triage by emitting a message to the kernel log that an
> interface was renamed while UP.
>
> [1] https://www.kernel.org/doc/Documentation/networking/netconsole.rst
> [2] https://lore.kernel.org/netdev/[email protected]/
>
> Signed-off-by: Andy Ren <[email protected]>
> ---
>
> Notes:
> Changes from v1->v2
> - Added placeholder comment in place of removed IFF_LIVE_RENAME_OK flag
> - Added extra logging hints to indicate whether a network interface was
> renamed while UP
>
> Changes from v2->v3
> - Patch description changes
>
> include/linux/netdevice.h | 4 +---
> net/core/dev.c | 19 ++-----------------
> net/core/failover.c | 6 +++---
> 3 files changed, 6 insertions(+), 23 deletions(-)
>
Reviewed-by: David Ahern <[email protected]>
Hello:
This patch was applied to netdev/net-next.git (master)
by David S. Miller <[email protected]>:
On Mon, 7 Nov 2022 09:42:42 -0800 you wrote:
> Allow a network interface to be renamed when the interface
> is up.
>
> As described in the netconsole documentation [1], when netconsole is
> used as a built-in, it will bring up the specified interface as soon as
> possible. As a result, user space will not be able to rename the
> interface since the kernel disallows renaming of interfaces that are
> administratively up unless the 'IFF_LIVE_RENAME_OK' private flag was set
> by the kernel.
>
> [...]
Here is the summary with links:
- [net-next,v3] net/core: Allow live renaming when an interface is up
https://git.kernel.org/netdev/net-next/c/bd039b5ea2a9
You are awesome, thank you!
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