[Bug 2056555] Re: Python can't write to /proc files

[Imai Tomoki]

This issue seems to be caused by App Armor's profile
"unprivileged_userns".

dmesg has the following report.

-----
[ 2229.188009] audit: type=1400 audit(1714466038.573:555): apparmor="DENIED" operation="capable" class="cap" profile="unprivileged_userns" pid=20223 comm="texinfo-dummy-n" capability=21  capname="sys_admin"
-----

And can be temporally resolved by unloading the profile.

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$ sudo apparmor_parser -R /etc/apparmor.d/unprivileged_userns 
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https://bugs.launchpad.net/bugs/2056555

Title:
  Python can't write to /proc files

Status in dash package in Ubuntu:
  Confirmed

Bug description:
  Occurs since an update around March 2 Ubuntu 24.04.

  Bitbake is broken due to file permission problem.

  Traceback (most recent call last):
    File "/home/hains/openpli-oe-core/bitbake/bin/bitbake-worker", line 268, in child
      bb.utils.disable_network(uid, gid)
    File "/home/hains/openpli-oe-core/bitbake/lib/bb/utils.py", line 1653, in disable_network
      with open("/proc/self/uid_map", "w") as f:
  PermissionError: [Errno 1] Operation not permitted

  Test code

  with open("/proc/self/uid_map", "w") as f:
  	f.write("%s %s 1" % (1000, 1000))

  ProblemType: Bug
  DistroRelease: Ubuntu 24.04
  Package: dash 0.5.12-6ubuntu4
  ProcVersionSignature: Ubuntu 6.8.0-11.11-generic 6.8.0-rc4
  Uname: Linux 6.8.0-11-generic x86_64
  NonfreeKernelModules: nvidia_modeset nvidia
  ApportVersion: 2.28.0-0ubuntu1
  Architecture: amd64
  CasperMD5CheckResult: unknown
  CurrentDesktop: ubuntu:GNOME
  Date: Fri Mar  8 14:34:08 2024
  InstallationDate: Installed on 2023-03-24 (350 days ago)
  InstallationMedia: Ubuntu 22.10 "Kinetic Kudu" - Release amd64 (20221020)
  SourcePackage: dash
  UpgradeStatus: Upgraded to noble on 2024-01-10 (58 days ago)

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