[Bug 1905245] Re: "Failed to parse bus message: Invalid argument" with Linux 5.8

[Dan Streetman]

** Description changed:

  [impact]
  
  newer kernels introduced a new capability, and existing systemd doesn't
  have the name mapping for the new cap (since the mapping table is
  generated at systemd compile time), so it fails when trying to map the
  capability to a user-facing name, which causes failure when running
  commands like 'systemctl show'
  
  [test case]
  
  install a focal system, and install the 5.8 (or newer) kernel, e.g. from
  linux-generic-hwe-20.04-edge, and reboot into the new kernel.
  
  Find any service that does not specify its CapabilityBoundingSet; e.g.
  'apparmor', and run systemctl show on it:
  
  ubuntu at lp1905245-f:~$ systemctl show -p CapabilityBoundingSet apparmor
  Failed to parse bus message: Invalid argument
  
  the command should correctly show the value, e.g.:
  $ systemctl show -p CapabilityBoundingSet apparmor
  CapabilityBoundingSet=cap_chown cap_dac_override ...etc...
  
  [regression potential]
  
  a regression would likely occur while systemd is parsing or printing or
  otherwise handling kernel capabilities. A regression could happen when
  running systemd commands, such as systemctl, or when pid1 is managing
  services.
  
  [scope]
  
- this is needed only in focal (and possibly bionic).
+ this is needed only in focal and bionic.
  
  This is fixed upstream by PR 16424:
  https://github.com/systemd/systemd/pull/16424
  which was first included in v246, so this is already fixed in groovy and later.
  
- this was introduced externally from systemd, with the new capability in the kernel, so this fix technically is needed in x/b/f. However, x is unlikely to get a new kernel capability during the rest of its life cycle.
- For b, unless a kernel is added that includes a new capability, this patch is not needed.
+ This was introduced upstream in systemd by commit
+ 52610b020c077ee769c6923249f7e6c4e99d2980 which was first included in
+ v235, so this bug does not exist in Xenial.
+ 
+ This bug will reproduce on any system running under the 5.8 kernel, with
+ the new capability, if the systemd binary was compiled with kernel
+ headers that do not include the new capability. This means this is
+ reproducable on bare-metal/vm instances running 5.8, as well as
+ containers on hosts running 5.8. Therefore, while bionic may not ever
+ receive a new kernel with added capability, it still needs to be patched
+ to avoid the bug on a bionic container running on a host with the 5.8
+ kernel.
  
  [other info]
  
  there is a testcase-only related bug 1905044
  
  [original description]
  
  When I run `systemctl show myservice.service`, I get the following error
  message:
  
     Failed to parse bus message: Invalid argument
  
  systemd version: 245.4-4ubuntu3.3
  linux version: 5.8.0-29-generic #31~20.04.1-Ubuntu  (From linux-generic-hwe-20.04-edge)
  
  This is a bug that has been fixed in Debian. See https://bugs.debian.org
  /cgi-bin/bugreport.cgi?bug=964926
  
  Please can we port the fix to the ubuntu 20.04 version.

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1905245

Title:
  "Failed to parse bus message: Invalid argument" with Linux 5.8

Status in systemd package in Ubuntu:
  Fix Released
Status in systemd source package in Bionic:
  In Progress
Status in systemd source package in Focal:
  In Progress

Bug description:
  [impact]

  newer kernels introduced a new capability, and existing systemd
  doesn't have the name mapping for the new cap (since the mapping table
  is generated at systemd compile time), so it fails when trying to map
  the capability to a user-facing name, which causes failure when
  running commands like 'systemctl show'

  [test case]

  install a focal system, and install the 5.8 (or newer) kernel, e.g.
  from linux-generic-hwe-20.04-edge, and reboot into the new kernel.

  Find any service that does not specify its CapabilityBoundingSet; e.g.
  'apparmor', and run systemctl show on it:

  ubuntu at lp1905245-f:~$ systemctl show -p CapabilityBoundingSet apparmor
  Failed to parse bus message: Invalid argument

  the command should correctly show the value, e.g.:
  $ systemctl show -p CapabilityBoundingSet apparmor
  CapabilityBoundingSet=cap_chown cap_dac_override ...etc...

  [regression potential]

  a regression would likely occur while systemd is parsing or printing
  or otherwise handling kernel capabilities. A regression could happen
  when running systemd commands, such as systemctl, or when pid1 is
  managing services.

  [scope]

  this is needed only in focal and bionic.

  This is fixed upstream by PR 16424:
  https://github.com/systemd/systemd/pull/16424
  which was first included in v246, so this is already fixed in groovy and later.

  This was introduced upstream in systemd by commit
  52610b020c077ee769c6923249f7e6c4e99d2980 which was first included in
  v235, so this bug does not exist in Xenial.

  This bug will reproduce on any system running under the 5.8 kernel,
  with the new capability, if the systemd binary was compiled with
  kernel headers that do not include the new capability. This means this
  is reproducable on bare-metal/vm instances running 5.8, as well as
  containers on hosts running 5.8. Therefore, while bionic may not ever
  receive a new kernel with added capability, it still needs to be
  patched to avoid the bug on a bionic container running on a host with
  the 5.8 kernel.

  [other info]

  there is a testcase-only related bug 1905044

  [original description]

  When I run `systemctl show myservice.service`, I get the following
  error message:

     Failed to parse bus message: Invalid argument

  systemd version: 245.4-4ubuntu3.3
  linux version: 5.8.0-29-generic #31~20.04.1-Ubuntu  (From linux-generic-hwe-20.04-edge)

  This is a bug that has been fixed in Debian. See
  https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=964926

  Please can we port the fix to the ubuntu 20.04 version.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1905245/+subscriptions