From 7e55f20c1f31f78ed22719b129743bbc243a3feb Mon Sep 17 00:00:00 2001 From: Felix Fietkau Date: Mon, 4 Sep 2023 15:28:59 +0200 Subject: kernel: backport support for renaming netdevs while up Will be used in upcoming hostapd changes Signed-off-by: Felix Fietkau (cherry picked from commit 77c45ddd86b0dff7765e30f7846cbdef34fa93ce) --- ...low-live-renaming-when-an-interface-is-up.patch | 136 +++++++++++++++++++++ 1 file changed, 136 insertions(+) create mode 100644 target/linux/generic/backport-5.15/794-v6.2-net-core-Allow-live-renaming-when-an-interface-is-up.patch (limited to 'target/linux/generic/backport-5.15') diff --git a/target/linux/generic/backport-5.15/794-v6.2-net-core-Allow-live-renaming-when-an-interface-is-up.patch b/target/linux/generic/backport-5.15/794-v6.2-net-core-Allow-live-renaming-when-an-interface-is-up.patch new file mode 100644 index 0000000000..bd58db2e77 --- /dev/null +++ b/target/linux/generic/backport-5.15/794-v6.2-net-core-Allow-live-renaming-when-an-interface-is-up.patch @@ -0,0 +1,136 @@ +From: Andy Ren +Date: Mon, 7 Nov 2022 09:42:42 -0800 +Subject: [PATCH] net/core: Allow live renaming when an interface is up + +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/20221102002420.2613004-1-andy.ren@getcruise.com/ + +Signed-off-by: Andy Ren +Reviewed-by: Ido Schimmel +Reviewed-by: David Ahern +Signed-off-by: David S. Miller +--- + +--- a/include/linux/netdevice.h ++++ b/include/linux/netdevice.h +@@ -1642,7 +1642,6 @@ 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) + */ +@@ -1677,7 +1676,7 @@ 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), + }; + +@@ -1711,7 +1710,6 @@ 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 */ +--- a/net/core/dev.c ++++ b/net/core/dev.c +@@ -1222,22 +1222,6 @@ int dev_change_name(struct net_device *d + + 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) { +@@ -1254,7 +1238,8 @@ int dev_change_name(struct net_device *d + } + + 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; +--- a/net/core/failover.c ++++ b/net/core/failover.c +@@ -80,14 +80,14 @@ static int failover_slave_register(struc + 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 + + 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)) -- cgit v1.2.3