touch-packages team mailing list archive

[Michael Vogt <michael.vogt@xxxxxxxxxxxxx>]

@John Yay! The patches look great, thanks a lot! I leave the decision on
hashing vs mtime to you/the security team. For me the mtime approach is
good enough (unless I miss some failure case that is relatively easy to
trigger, it seems it covers all but the most pathological cases) and it
will solve this bug in a nice and clean way.

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https://bugs.launchpad.net/bugs/1460152

Title:
  apparmor cache not updated when apparmor.d rules change (breaks
  15.04/stable -> 15.04/edge updates)

Status in Snappy Ubuntu:
  In Progress
Status in Snappy 15.04 series:
  Fix Committed
Status in apparmor package in Ubuntu:
  New

Bug description:
  The apparmor cache gets confused easily on upgrade.

  Here is what happens:
  - boot stable, /etc/apparmor.d/cache/usr.bin.ubuntu-core-launcher is mtime of now because we generate the cache on boot
  - upgrade to edge, /etc/apparmor.d/usr.bin.ubuntu-core-launcher is updated and has the mtime of T (yesterday) when the file was put into the package
  - on the next reboot the apparmor_parser compares the mtime of the cache/usr.bin.ubuntu-core-launcher (very very recent) with the mtime of the souce usr.bin.ubuntu-core-launcher (much older)
  -> cache does is *not* re-generate

  Possible solution:
  - clear cache on upgrade
  - make apparmor_parser store mtime of the source file in the header
  - make apparmor_parser use set the cache file to the mtime of the source file used to generate the cache and re-generate if those get out-of-sync

  Original description:
  ----------------------

  Rick Spencer ran into the situation that he ended up with a snappy image that gave the following error:
  """
  apparmor="DENIED" operation="mkdir" profile="/usr/bin/ubuntu-core-launcher" name="/tmp/snap.0_pastebinit.mvo_em33Zz/" pid=1092 comm="ubuntu-core-lau" requested_mask="c" denied_mask="c" fsuid=0 ouid=0
  """

  Running:
  $ sudo apparmor_parser --skip-cache -r /etc/apparmor.d/usr.bin.ubuntu-core-launcher
  fixes it.

  This strongly indicates that the cache has the old content and did not
  get re-generated on upgrade or image build.

  I also managed to reproduce this via:
  15.04/stable->15.04/edge

  The image is here:
  https://drive.google.com/open?id=0B1sb5ymdUGiLa0tUR0pGV3lzR1k&authuser=0

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