Performing verification for Focal. The affected user enabled -proposed and installed 5.4.0-66-generic to the system with a QLogic FastLinQ QL41000 Series 10/25/40/50GbE Controller.
They then set all interfaces down, and brought up the QLogic NIC only. # uname -rv 5.4.0-66-generic #74~18.04.2-Ubuntu SMP Fri Feb 5 11:17:31 UTC 2021 # nslookup internal.kubernetes.domain.example 10.1.0.10 Server: 10.1.0.10 Address: 10.1.0.10#53 Name: internal.kubernetes.domain.example Address: 10.48.24.11 # ethtool -k eno1 | grep tx-checksumming tx-checksumming: on # ethtool -k enp94s0f0 | grep tx-checksumming tx-checksumming: on DNS lookup to an internal kubernetes domain with IPIP type DNS lookups work as intended, with tx checksumming enabled. The kernel in -proposed fixes the issue, marking as verified. ** Tags removed: verification-needed-focal ** Tags added: verification-done-focal -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1909062 Title: qede: Kubernetes Internal DNS Failure due to QL41xxx NIC not supporting IPIP tx csum offload Status in linux package in Ubuntu: Fix Committed Status in linux source package in Focal: Fix Committed Status in linux source package in Groovy: Fix Committed Status in linux source package in Hirsute: Fix Committed Bug description: BugLink: https://bugs.launchpad.net/bugs/1909062 [Impact] For users with QLogic QL41xxx series NICs, such as the FastLinQ QL41000 Series 10/25/40/50GbE Controller, when they upgrade from the 4.15 kernel to the 5.4 kernel, Kubernetes Internal DNS requests will fail, due to these packets getting corrupted. Kubernetes uses IPIP tunnelled packets for internal DNS resolution, and this particular packet type is not supported for hardware tx checksum offload, and the packets end up corrupted when the qede driver attempts to checksum them. This only affects internal Kubernetes DNS, as regular DNS lookups to regular external domains will succeed, due to them not using IPIP packet types. [Fix] Marvell has developed a fix for the qede driver, which checks the packet type, and if it is IPPROTO_IPIP, then csum offloads are disabled for socket buffers of type IPIP. commit 5d5647dad259bb416fd5d3d87012760386d97530 Author: Manish Chopra <mani...@marvell.com> Date: Mon Dec 21 06:55:30 2020 -0800 Subject: qede: fix offload for IPIP tunnel packets Link: https://github.com/torvalds/linux/commit/5d5647dad259bb416fd5d3d87012760386d97530 This commit landed in mainline in 5.11-rc3. The commit was accepted into upstream stable 4.14.215, 4.19.167, 5.4.89 and 5.10.7. Note, this SRU isn't targeted for Bionic due to tx csum offload support only landing in 5.0 and onward, meaning the 4.15 kernel still works even without this patch. Because of this, Bionic can pick the patch up naturally from upstream stable. [Testcase] The system must have a QLogic QL41xxx series NIC fitted, and needs to be a part of a Kubernetes cluster. Firstly, get a list of all devices in the system: $ sudo ifconfig Next, set all devices down with: $ sudo ifconfig <device> down Next, bring up the QLogic QL41xxx device: $ sudo ifconfig <qlogic nic device> up Then, attempt to lookup an internal Kubernetes domain: $ nslookup <internal kubernetes domain address> Without the patch, the connection will time out: ;; connection timed out; no servers could be reached If we look at packet traces with tcpdump, we see it leaves the source, but never arrives at the destination. There is a test kernel available in the following ppa: https://launchpad.net/~mruffell/+archive/ubuntu/sf297772-test If you install it, then Kubernetes internal DNS lookups will succeed. [Where problems could occur] If a regression were to occur, then users of the qede driver would be affected. This is limited to those with QLogic QL41xxx series NICs. The patch explicitly checks for IPIP type packets, so only those particular packets would be affected. Since IPIP type packets are uncommon, it would not cause a total outage on regression, since most packets are not IPIP tunnelled. It could potentially cause problems for users who frequently handle VPN or Kubernetes internal DNS traffic. A workaround would be to use ethtool to disable tx csum offload for all packet types, or to revert to an older kernel. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1909062/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
