Bug#953674: nautilus: Thumbnail generation silently fails without unprivileged_userns_clone

[Simon McVittie]

On Thu, 12 Mar 2020 at 17:14:12 +1100, Ian Wienand wrote:
> 7836  write(2, "No permissions to creating new namespace, likely because the kernel does not allow non-privileged user namespaces. On e.g. debian this can be enabled with 'sysctl kernel.unprivileged_userns_clone=1'.", 199 <unfinished ...>
> ---
> 
> Setting kernel.unprivileged_userns_clone = 1 made thumbnails work again.

Is /usr/bin/bwrap setuid root? If you haven't changed it, its permissions
should be something like this:

$ ls -l /usr/bin/bwrap
-rwsr-xr-x 1 root root 59680 Nov 28 11:14 /usr/bin/bwrap

It's meant to work on Debian kernels if it is setuid root *or*
if the kernel.unprivileged_userns_clone sysctl is set to 1.

    smcv