[Bug 1748310] Re: [SRU][xenial]boot stalls looking for entropy in FIPS mode

[Vineetha Hari Pai]

bionic debdiff

** Attachment added: "debdiff.bionic"
   https://bugs.launchpad.net/ubuntu/+source/libgcrypt20/+bug/1748310/+attachment/5055412/+files/debdiff.bionic

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Title:
  [SRU][xenial]boot stalls looking for entropy in FIPS mode

Status in libgcrypt20 package in Ubuntu:
  New
Status in libgcrypt20 source package in Xenial:
  New

Bug description:
  [IMPACT]
  libgcrypt20 is not a FIPS certified library. On a machine running FIPS enabled kernel, the library by default goes into FIPS mode if /proc/sys/crypto/fips_enabled=1. FIPS mode is not a configurable compile option currently in the library. Hence FIPS code paths are always executed on a FIPS enabled machine. In FIPS mode, it runs self tests and integrity checks and it looks for quality entropy from /dev/random.

  On encrypted installations, cryptsetup uses libgcrypt20. During boot
  on an encrypted machine running in FIPS mode, cryptsetup invokes
  libgcrypt and it stalls looking for quality entropy from /dev/random.
  This results in significant delays during startup. The issue was
  reported by a FIPS customer.

  The issue impacts libgcrypt versions in xenial and bionic.

  lsb_release -rd
  Description:	Ubuntu 16.04.3 LTS
  Release:	16.04

  version - 1.6.5-2ubuntu0.3

  lsb_release -rd
  Description:	Ubuntu Bionic Beaver (development branch)
  Release:	18.04

  version - 1.8.1-4

  [FIX]
  Disable the two self tests that require entropy from /dev/random during boot in FIPS mode.

  [TEST]
  Tested on a VM installed with xenial desktop iso and one with xenial server iso. Enabled full disk encryption during install. Tested with and without FIPS. No delays were observed during boot after the fix patch was applied.

  With FIPS enabled on encrypted install, without the patch fix, the
  boot stalls before and after prompting for decryption password.

  [REGRESSION POTENTIAL]
  The regression potential for this is small. The two self tests disabled does not impact any other functionality available in fips mode and non-fips mode of the library.

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