Control netfilter flow table timeouts via sysctl

[Bodong Wang]

* Explain the bug(s)

TCP and UDP connections may be offloaded from nf conntrack to nf flow table.
Offloaded connections are aged after 30 seconds of inactivity.
Once aged, ownership is returned to conntrack with a hard coded tcp/udp pickup time of 120/30 seconds, after which the connection may be deleted.

The current hard-coded pickup intervals may introduce a very aggressive aging policy. For example, offloaded tcp connections in established state will timeout from nf conntrack after just 150 seconds of inactivity, instead of 5 days. In addition, the hard-coded 30 second offload timeout period can significantly increase the hardware insertion rate requirements in some use cases.

* Brief explanation of fixes

This patchset provides the user with the ability to configure protocol specific offload timeout and pickup intervals via sysctl.

The first and second patches revert the existing non-upstream solution.
The next two patches introduce the sysctl configuration for tcp and udp protocols.
The last patch modifies nf flow table aging mechanisms to use the configured time intervals.

* How to test

Control tcp/udp connection timeout using the following sysctl parameters:
net.netfilter.nf_flowtable_tcp_pickup = 120 net.netfilter.nf_flowtable_tcp_timeout = 30 net.netfilter.nf_flowtable_udp_pickup = 30 net.netfilter.nf_flowtable_udp_timeout = 30

* What it could break.

Existing configuration scripts – not kernel related

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-focal' to 'verification-done-focal'. If the problem still exists, change the tag 'verification-needed-focal' to 'verification-failed-focal'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux-bluefield - 5.4.0-1019.22

---------------
linux-bluefield (5.4.0-1019.22) focal; urgency=medium

  * focal/linux-bluefield: 5.4.0-1019.22 -proposed tracker (LP: #1942533)

  * Focal update: v5.4.134 upstream stable release (LP: #1939440)
    - [Config] bluefield: CONFIG_BATTERY_RT5033=m

  * Fix fragmentation support for TC connection tracking (LP: #1940872)
    - net/sched: act_ct: fix restore the qdisc_skb_cb after defrag
    - net/sched: act_ct: fix miss set mru for ovs after defrag in act_ct
    - net/sched: fix miss init the mru in qdisc_skb_cb
    - net/sched: act_ct: fix wild memory access when clearing fragments
    - Revert "net/sched: act_ct: Fix skb double-free in tcf_ct_handle_fragments()
      error flow"
    - net/sched: act_mirred: refactor the handle of xmit
    - net/sched: The error lable position is corrected in ct_init_module
    - net/sched: sch_frag: add generic packet fragment support.
    - ipv6: add ipv6_fragment hook in ipv6_stub

  * Add the upcoming BlueField-3 device ID (LP: #1941803)
    - net/mlx5: Update the list of the PCI supported devices

  * CT state not reset when packet redirected to different port (LP: #1940448)
    - Revert "UBUNTU: SAUCE: net/sched: act_mirred: Reset ct when reinserting skb
      back into queue"
    - net: sched: act_mirred: Reset ct info when mirror/redirect skb

  * Export xfrm_policy_lookup_bytype function (LP: #1934313)
    - SAUCE: xfrm: IPsec Export xfrm_policy_lookup_bytype function

  [ Ubuntu: 5.4.0-85.95 ]

  * focal/linux: 5.4.0-85.95 -proposed tracker (LP: #1942557)
  * please drop virtualbox-guest-dkms virtualbox-guest-source (LP: #1933248)
    - [Config] Disable virtualbox dkms build
  * Packaging resync (LP: #1786013)
    - debian/dkms-versions -- update from kernel-versions (main/2021.09.06)
  * LRMv5: switch primary version handling to kernel-versions data set
    (LP: #1928921)
    - [Packaging] switch to kernel-versions
  * disable “CONFIG_HISI_DMA” config for ubuntu version (LP: #1936771)
    - Disable CONFIG_HISI_DMA
    - [Config] Record hisi_dma no longer built for arm64
  * memory leaking when removing a profile (LP: #1939915)
    - apparmor: Fix memory leak of profile proxy
  * CryptoExpress EP11 cards are going offline (LP: #1939618)
    - s390/zcrypt: Support for CCA protected key block version 2
    - s390: Replace zero-length array with flexible-array member
    - s390/zcrypt: Use scnprintf() for avoiding potential buffer overflow
    - s390/zcrypt: replace snprintf/sprintf with scnprintf
    - s390/ap: Remove ap device suspend and resume callbacks
    - s390/zcrypt: use fallthrough;
    - s390/zcrypt: use kvmalloc instead of kmalloc for 256k alloc
    - s390/ap: remove power management code from ap bus and drivers
    - s390/ap: introduce new ap function ap_get_qdev()
    - s390/zcrypt: use kzalloc
    - s390/zcrypt: fix smatch warnings
    - s390/zcrypt: code beautification and struct field renames
    - s390/zcrypt: split ioctl function into smaller code units
    - s390/ap: rename and clarify ap state machine related stuff
    - s390/zcrypt: provide cex4 cca sysfs attributes for cex3
    - s390/ap: rework cry...