137 lines
5.3 KiB
Diff
137 lines
5.3 KiB
Diff
From: Andy Ren <andy.ren@getcruise.com>
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Date: Mon, 7 Nov 2022 09:42:42 -0800
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Subject: [PATCH] net/core: Allow live renaming when an interface is up
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Allow a network interface to be renamed when the interface
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is up.
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As described in the netconsole documentation [1], when netconsole is
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used as a built-in, it will bring up the specified interface as soon as
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possible. As a result, user space will not be able to rename the
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interface since the kernel disallows renaming of interfaces that are
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administratively up unless the 'IFF_LIVE_RENAME_OK' private flag was set
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by the kernel.
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The original solution [2] to this problem was to add a new parameter to
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the netconsole configuration parameters that allows renaming of
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the interface used by netconsole while it is administratively up.
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However, during the discussion that followed, it became apparent that we
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have no reason to keep the current restriction and instead we should
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allow user space to rename interfaces regardless of their administrative
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state:
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1. The restriction was put in place over 20 years ago when renaming was
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only possible via IOCTL and before rtnetlink started notifying user
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space about such changes like it does today.
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2. The 'IFF_LIVE_RENAME_OK' flag was added over 3 years ago in version
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5.2 and no regressions were reported.
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3. In-kernel listeners to 'NETDEV_CHANGENAME' do not seem to care about
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the administrative state of interface.
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Therefore, allow user space to rename running interfaces by removing the
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restriction and the associated 'IFF_LIVE_RENAME_OK' flag. Help in
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possible triage by emitting a message to the kernel log that an
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interface was renamed while UP.
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[1] https://www.kernel.org/doc/Documentation/networking/netconsole.rst
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[2] https://lore.kernel.org/netdev/20221102002420.2613004-1-andy.ren@getcruise.com/
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Signed-off-by: Andy Ren <andy.ren@getcruise.com>
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Reviewed-by: Ido Schimmel <idosch@nvidia.com>
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Reviewed-by: David Ahern <dsahern@kernel.org>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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--- a/include/linux/netdevice.h
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+++ b/include/linux/netdevice.h
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@@ -1667,7 +1667,6 @@ struct net_device_ops {
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* @IFF_FAILOVER: device is a failover master device
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* @IFF_FAILOVER_SLAVE: device is lower dev of a failover master device
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* @IFF_L3MDEV_RX_HANDLER: only invoke the rx handler of L3 master device
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- * @IFF_LIVE_RENAME_OK: rename is allowed while device is up and running
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* @IFF_TX_SKB_NO_LINEAR: device/driver is capable of xmitting frames with
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* skb_headlen(skb) == 0 (data starts from frag0)
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* @IFF_CHANGE_PROTO_DOWN: device supports setting carrier via IFLA_PROTO_DOWN
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@@ -1703,7 +1702,7 @@ enum netdev_priv_flags {
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IFF_FAILOVER = 1<<27,
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IFF_FAILOVER_SLAVE = 1<<28,
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IFF_L3MDEV_RX_HANDLER = 1<<29,
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- IFF_LIVE_RENAME_OK = 1<<30,
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+ /* was IFF_LIVE_RENAME_OK */
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IFF_TX_SKB_NO_LINEAR = BIT_ULL(31),
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IFF_CHANGE_PROTO_DOWN = BIT_ULL(32),
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};
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@@ -1738,7 +1737,6 @@ enum netdev_priv_flags {
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#define IFF_FAILOVER IFF_FAILOVER
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#define IFF_FAILOVER_SLAVE IFF_FAILOVER_SLAVE
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#define IFF_L3MDEV_RX_HANDLER IFF_L3MDEV_RX_HANDLER
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-#define IFF_LIVE_RENAME_OK IFF_LIVE_RENAME_OK
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#define IFF_TX_SKB_NO_LINEAR IFF_TX_SKB_NO_LINEAR
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/* Specifies the type of the struct net_device::ml_priv pointer */
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--- a/net/core/dev.c
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+++ b/net/core/dev.c
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@@ -1188,22 +1188,6 @@ int dev_change_name(struct net_device *d
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net = dev_net(dev);
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- /* Some auto-enslaved devices e.g. failover slaves are
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- * special, as userspace might rename the device after
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- * the interface had been brought up and running since
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- * the point kernel initiated auto-enslavement. Allow
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- * live name change even when these slave devices are
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- * up and running.
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- *
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- * Typically, users of these auto-enslaving devices
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- * don't actually care about slave name change, as
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- * they are supposed to operate on master interface
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- * directly.
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- */
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- if (dev->flags & IFF_UP &&
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- likely(!(dev->priv_flags & IFF_LIVE_RENAME_OK)))
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- return -EBUSY;
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-
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down_write(&devnet_rename_sem);
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if (strncmp(newname, dev->name, IFNAMSIZ) == 0) {
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@@ -1220,7 +1204,8 @@ int dev_change_name(struct net_device *d
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}
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if (oldname[0] && !strchr(oldname, '%'))
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- netdev_info(dev, "renamed from %s\n", oldname);
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+ netdev_info(dev, "renamed from %s%s\n", oldname,
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+ dev->flags & IFF_UP ? " (while UP)" : "");
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old_assign_type = dev->name_assign_type;
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dev->name_assign_type = NET_NAME_RENAMED;
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--- a/net/core/failover.c
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+++ b/net/core/failover.c
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@@ -80,14 +80,14 @@ static int failover_slave_register(struc
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goto err_upper_link;
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}
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- slave_dev->priv_flags |= (IFF_FAILOVER_SLAVE | IFF_LIVE_RENAME_OK);
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+ slave_dev->priv_flags |= IFF_FAILOVER_SLAVE;
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if (fops && fops->slave_register &&
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!fops->slave_register(slave_dev, failover_dev))
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return NOTIFY_OK;
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netdev_upper_dev_unlink(slave_dev, failover_dev);
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- slave_dev->priv_flags &= ~(IFF_FAILOVER_SLAVE | IFF_LIVE_RENAME_OK);
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+ slave_dev->priv_flags &= ~IFF_FAILOVER_SLAVE;
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err_upper_link:
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netdev_rx_handler_unregister(slave_dev);
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done:
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@@ -121,7 +121,7 @@ int failover_slave_unregister(struct net
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netdev_rx_handler_unregister(slave_dev);
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netdev_upper_dev_unlink(slave_dev, failover_dev);
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- slave_dev->priv_flags &= ~(IFF_FAILOVER_SLAVE | IFF_LIVE_RENAME_OK);
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+ slave_dev->priv_flags &= ~IFF_FAILOVER_SLAVE;
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if (fops && fops->slave_unregister &&
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!fops->slave_unregister(slave_dev, failover_dev))
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