[Bug 1916485] Re: test -x fails inside shell scripts in containers

[Martin Pitt]

I've been scratching my head over this regression [1] for a while now,
in the context of running a hirsute container on a 20.04 host (in
particular, a GitHub workflow machine) In my case, the symptom is that
after upgrading glibc, `which` is broken; that of course also uses
faccessat(), similar to test -x.

I tried all sorts of the "usual" workarounds, as seccomp has been giving
trouble for a while now [2]. But this failure is robust against fuse-
overlayfs vs. vfs (inefficient full copies of the file system), root vs.
user podman, podman vs. docker, and, relevant for this bug, it *also
happens* with --security-opt=seccomp=unconfined and/org --privileged,
both of which should disable seccomp.

Hence I believe this bug can't at least only be in libseccomp.


[1] https://github.com/martinpitt/umockdev/runs/1984769591?check_suite_focus=true#step:3:1019
[2] https://bugzilla.redhat.com/show_bug.cgi?id=1900021

** Bug watch added: Red Hat Bugzilla #1900021
   https://bugzilla.redhat.com/show_bug.cgi?id=1900021

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https://bugs.launchpad.net/bugs/1916485

Title:
  test -x fails inside shell scripts in containers

Status in glibc package in Ubuntu:
  Triaged
Status in libseccomp package in Ubuntu:
  Fix Committed
Status in glibc source package in Hirsute:
  Triaged
Status in libseccomp source package in Hirsute:
  Fix Committed

Bug description:
  glibc regression causes test -x to fail inside scripts inside
  docker/podman, dash and bash are broken, mksh and zsh are fine:

  root at 0df2ce5d7a46:/# test -x /usr/bin/gpg || echo Fail
  root at 0df2ce5d7a46:/# dash -c "test -x /usr/bin/gpg || echo Fail"
  Fail
  root at 0df2ce5d7a46:/# bash -c "test -x /usr/bin/gpg || echo Fail"
  Fail
  root at 0df2ce5d7a46:/# mksh -c "test -x /usr/bin/gpg || echo Fail"
  root at 0df2ce5d7a46:/# zsh -c "test -x /usr/bin/gpg || echo Fail"
  root at 0df2ce5d7a46:/#

  root at 0df2ce5d7a46:/# zsh -c "[ -x /usr/bin/gpg ] || echo Fail"
  root at 0df2ce5d7a46:/# mksh -c "[ -x /usr/bin/gpg ] || echo Fail"
  root at 0df2ce5d7a46:/# dash -c "[ -x /usr/bin/gpg ] || echo Fail"
  Fail
  root at 0df2ce5d7a46:/# bash -c "[ -x /usr/bin/gpg ] || echo Fail"
  Fail

  The -f flag works, as does /usr/bin/test:
  # bash -c "test -f /usr/bin/gpg  || echo Fail"
  # bash -c "/usr/bin/test -x /usr/bin/gpg  || echo Fail"
  #

  [Original bug report]
  root at 84b750e443f8:/# lsb_release -rd
  Description:	Ubuntu Hirsute Hippo (development branch)
  Release:	21.04
  root at 84b750e443f8:/# dpkg -l gnupg apt
  Desired=Unknown/Install/Remove/Purge/Hold
  | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
  |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
  ||/ Name           Version         Architecture Description
  +++-==============-===============-============-==========================================
  ii  apt            2.1.20          amd64        commandline package manager
  ii  gnupg          2.2.20-1ubuntu2 all          GNU privacy guard - a free PGP replacement

  Hi,
  for 3 days our CI pipelines to recreate Docker images fails for the Hirsute images. From comparison this seems to be caused by apt 2.1.20.

  The build fails with:

  0E: gnupg, gnupg2 and unupg1 do not seem to be installed, but one of
  them is required for this operation

  The simple Dockerfile to reproduce the error - "docker build -t foo ."

  FROM amd64/ubuntu:hirsute
  MAINTAINER Florian Lohoff <f at zz.de>

  USER root

  RUN apt-get update \
   && DEBIAN_FRONTEND=noninteractive apt-get -y install curl gnupg apt \
    && curl https://syncthing.net/release-key.txt | apt-key add -

  Breaking it down it this seems to be an issue that there is new
  functionality in apt/apt-key e.g. security hardening that docker
  prohibits in its containers. Running this manually works only in an
  --privileged container.

  So adding keys in unpriviledged container or possibly kubernetes will
  not work anymore.

  Flo

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