[Bug 2127766] Re: snap run --strace doesn't work with sudo-rs [sudo -E not supported]

[Andreas Hasenack]

The questing verification in comment #13 didn't show which
implementation of sudo (sudo or sudo-rs) was installed (this check is
part of the test plan), but I'll assume it was sudo-rs since it's the
default in questing and because the verification showed that the command
failed with the previous version of snapd:

ubuntu at u1:~$ snap run --strace hello
warning: preserving the entire environment is not supported, `-E` is ignored
error: exit status 1

And yeah, that error message ("`E` is ignored") definitely comes from
sudo-rs. All good.

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https://bugs.launchpad.net/bugs/2127766

Title:
  snap run --strace doesn't work with sudo-rs [sudo -E not supported]

Status in snapd:
  Fix Committed
Status in rust-sudo-rs package in Ubuntu:
  Won't Fix
Status in snapd package in Ubuntu:
  Fix Released
Status in snapd source package in Jammy:
  Fix Committed
Status in snapd source package in Noble:
  Fix Committed
Status in snapd source package in Plucky:
  Fix Committed
Status in snapd source package in Questing:
  Fix Committed

Bug description:
  [SRU] 2.73:
  https://bugs.launchpad.net/ubuntu/+source/snapd/+bug/2132084

  [ Impact ]

  Only impacts Ubuntu 25.10+
  With sudo-rs, -E` is ignored, which breaks snapd run --strace.

  [ Test Plan ]

  1. Reproduce with snapd deb < 2.73

  - Ensure sudo-rs installed
  - Run: snap run --strace <snap>.<app>
  - Expect: warning: preserving the entire environment is not supported, `-E` is ignored

  2. Prove fixed with snapd deb 2.73

  - Ensure sudo-rs installed
  - Run: snap run --strace <snap>.<app>
  - Expect: No warning

  ---original---

  sudo-rs became the default sudo in 25.10, which broke this snap run
  --strace,

  $ snap run --strace <snap>.<app>
  warning: preserving the entire environment is not supported, `-E` is ignored
  [sudo: authenticate] Password:
  error: exit status 1

  It does work if I switch back to GNU Coreutils' sudo. The reason being
  many required environment variables are no longer passed through, and
  the strace fails due to SNAP_INSTANCE_NAME not being set, before we
  get to execve'ing the snap application itself.

  I commented on this use case in the sudo-rs issue tracker:
  https://github.com/trifectatechfoundation/sudo-rs/issues/1299

  Maybe snapd needs to have a whitelist of environment variables?

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