/dev/stderr can't be used by the regular user inside the toolbox

[tnozicka]

Describe the bug /dev/stderr can't be used by the regular user inside the toolbox, although it works for the superuser. Outside of toolbox, regular users are allowed to write to /dev/stderr. This seems to be connected to procfs.

Steps how to reproduce the behaviour

$ toolbox create test
Created container: test
Enter with: toolbox enter test

$ # using image registry.fedoraproject.org/fedora-toolbox:37

$ toolbox enter test

$ echo foo > /dev/stderr
bash: /dev/stderr: Permission denied

$ sudo bash -c 'echo foo > /dev/stderr'
foo

Expected behaviour $ echo foo > /dev/stderr succeeds for regular users inside the toolbox

Actual behaviour

$ echo foo > /dev/stderr
bash: /dev/stderr: Permission denied

but succeeds for root

$ sudo bash -c 'echo foo > /dev/stderr'
foo

Output of toolbox --version (v0.0.90+)

$ toolbox --version
toolbox version 0.0.99.4

Toolbox package info (rpm -q toolbox)

$ rpm -q toolbox
toolbox-0.0.99.4-1.fc37.x86_64

Output of podman version

$ podman version
Client:       Podman Engine
Version:      4.4.2
API Version:  4.4.2
Go Version:   go1.19.6
Built:        Wed Mar  1 12:22:59 2023
OS/Arch:      linux/amd64

Podman package info (rpm -q podman)

$ rpm -q podman
podman-4.4.2-2.fc37.x86_64

Info about your OS Fedora Silverblue 37

Additional context