[Bug 2033422] Re: openssl: backport to jammy "clear method store / query cache confusion"

Thu Jan 4 11:00:50 UTC 2024

Here is an updated version.

I've dropped the extra patch for #1994165 and fixed the changelog where
I had swapped comments for two of the patches.

I've created a new PPA at
https://launchpad.net/~adrien-n/+archive/ubuntu/jammy-
openssl-2033422-sru because the version is unchanged (there has been no
new openssl security update).

** Patch added: "openssl_3.0.2-0ubuntu1.12-to-3.0.2-0ubuntu1.13.diff"
   https://bugs.launchpad.net/ubuntu/+source/openssl/+bug/2033422/+attachment/5736379/+files/openssl_3.0.2-0ubuntu1.12-to-3.0.2-0ubuntu1.13.diff

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https://bugs.launchpad.net/bugs/2033422

Title:
  openssl: backport to jammy "clear method store / query cache
  confusion"

Status in openssl package in Ubuntu:
  New
Status in openssl source package in Jammy:
  In Progress
Status in openssl source package in Lunar:
  Fix Released

Bug description:
  === SRU information ===
  [ATTENTION]
  This SRU contains THREE changes which are listed in the section below.

  [Meta]
  This bug is part of a series of three bugs for a single SRU.
  This ( #2033422 ) is the "central" bug with the global information and debdiff.

  This SRU addresses three issues with Jammy's openssl version:
  - http://pad.lv/1994165: ignored SMIME signature errors
  - http://pad.lv/2023545: imbca engine dumps core
  - http://pad.lv/2033422: very high CPU usage for concurrent TLS connections (this one)

  The SRU information has been added to the three bug reports and I am
  attaching the debdiff here only for all three.

  All the patches have been included in subsequent openssl 3.0.x
  releases which in turn have been included in subsequent Ubuntu
  releases. There has been no report of issues when updating to these
  Ubuntu releases.

  I have rebuilt the openssl versions and used abi-compliance-checker to
  compare the ABIs of the libraries in jammy and the one for the SRU.
  Both matched completely (FYI, mantic's matched completely too).

  I have also pushed the code to git (without any attempt to make it
  git-ubuntu friendly).

  https://code.launchpad.net/~adrien-n/ubuntu/+source/openssl/+git/openssl/+ref/jammy-
  sru

  I asked Brian Murray about phasing speed and he concurs a slow roll-out is probably better for openssl. There is a small uncertainty because a security update could come before the phasing is over, effectively fast-forwarding the SRU. Still, unless there is already a current pre-advisory, this is probably better than a 10% phasing which is over after only a couple days anyway.
  NB: at the moment openssl doesn't phase slowly so this needs to be implemented.

  [Impact]
  Severely degraded performance for concurrent operations compared to openssl 1.1. The performance is so degraded that some workloads fail due to timeouts or insufficient resources (noone magically has 5 times more machines). As a consequence, a number of people use openssl 1.1 instead and do not get security updates.

  [Test plan]
  Rafael Lopez has shared a simple benchmarks in http://pad.lv/2009544 with https://bugs.launchpad.net/ubuntu/+source/openssl/+bug/2009544/+attachment/5690224/+files/main.py .

  To test, follow these steps:
  - run "time python3 main.py" # using the aforementioned main.py script
  - apt install -t jammy-proposed libssl3
  - run "time python3 main.py"
  - compare the runtimes for the two main.py runs

  You can run this on x86_64, Raspberry Pi 4 or any machine, and get a
  very large speed-up in all cases. The improvements are not
  architecture-dependant.

  Using this changeset, I get the following numbers for ten runs on my
  laptop:

  3.0.2:
      real  2m5.567s
      user  4m3.948s
      sys   2m0.233s

  this SRU:
      real  0m23.966s
      user  2m35.687s
      sys   0m1.920s

  As can be easily seen, the speed-up is massive: system time is divided
  by 60 and overall wall clock time is roughly five times lower.

  In http://pad.lv/2009544 , Rafael also shared his performance numbers
  and they are relatable to these. He used slightly different versions
  (upstreams rather than patched with cherry-picks) but at least one of
  the version used does not include other performance change. He also
  used different hardware and this performance issue seems to depend on
  the number of CPUs available but also obtained a performance several
  times better. Results on a given machine vary also very little across
  runs (less than 2% variation on runs of size 10). They are also very
  similar on a Raspberry Pi 4 (8GB).

  The benchmark uses https://www.google.com/humans.txt which takes
  around 130ms to download on my machine but I modified the script to
  download something only 20ms away. Results are so close to the ones
  using humans.txt that they are within the error margin. This is
  consistent with the high-concurrency in the benchmark which both
  saturates CPU, and "hides" latencies that are relatively low.

  Finally, there are positive reports on github. Unfortunately they are
  not always completely targeted at these patches only and therefore I
  will not link directly to them but they have also been encouraging.

  [Where problems could occur]
  The change is spread over several patches which touch the internals of openssl. As such, the engine and provider functionality could be broken by these changes. Fortunately, in addition to upstream's code review, these patches are included in openssl 3.0.4 (iirc) and therefore in kinetic. No issue related to these changes was reported on launchpad or upstream.

  However, it is possible that there were more patch dependencies than
  these in either 3.0.3 or 3.0.4. In that case there could be problems.

  [Patches]
  The patches come directly from upstream and apply cleanly.

  https://github.com/openssl/openssl/pull/18151#issuecomment-1118535602

  * https://git.launchpad.net/~adrien-n/ubuntu/+source/openssl/tree/debian/patches/jammy-sru-0001-Drop-ossl_provider_clear_all_operation_bits-and-all-.patch?h=jammy-sru&id=04ef023920ab08fba214817523fba897527dfff0
  * https://git.launchpad.net/~adrien-n/ubuntu/+source/openssl/tree/debian/patches/jammy-sru-0002-Refactor-method-construction-pre-and-post-condition.patch?h=jammy-sru&id=04ef023920ab08fba214817523fba897527dfff0
  * https://git.launchpad.net/~adrien-n/ubuntu/+source/openssl/tree/debian/patches/jammy-sru-0003-Don-t-empty-the-method-store-when-flushing-the-query.patch?h=jammy-sru&id=04ef023920ab08fba214817523fba897527dfff0
  * https://git.launchpad.net/~adrien-n/ubuntu/+source/openssl/tree/debian/patches/jammy-sru-0004-Make-it-possible-to-remove-methods-by-the-provider-t.patch?h=jammy-sru&id=04ef023920ab08fba214817523fba897527dfff0
  * https://git.launchpad.net/~adrien-n/ubuntu/+source/openssl/tree/debian/patches/jammy-sru-0005-Complete-the-cleanup-of-an-algorithm-in-OSSL_METHOD_.patch?h=jammy-sru&id=04ef023920ab08fba214817523fba897527dfff0
  * https://git.launchpad.net/~adrien-n/ubuntu/+source/openssl/tree/debian/patches/jammy-sru-0006-For-child-libctx-provider-don-t-count-self-reference.patch?h=jammy-sru&id=04ef023920ab08fba214817523fba897527dfff0
  * https://git.launchpad.net/~adrien-n/ubuntu/+source/openssl/tree/debian/patches/jammy-sru-0007-Add-method-store-cache-flush-and-method-removal-to-n.patch?h=jammy-sru&id=04ef023920ab08fba214817523fba897527dfff0

  === Original description ===

  This is about SRU'ing to Jammy the patches at
  https://github.com/openssl/openssl/pull/18151#issuecomment-1118535602
  . They're purely performance but their impact is large. They have been
  released as part of openssl 3.0.4 (they're among the first after
  3.0.3) which has been included in Kinetic.

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