bug#45198: 28.0.50; Sandbox mode

[Philipp Stephani]

Am Mo., 14. Dez. 2020 um 12:05 Uhr schrieb Philipp Stephani
<p.stephani2@gmail.com>:
>
> > >> - This will need someone else doing the implementation.
> > > Looks like we already have a volunteer for macOS.
> > > For Linux, this shouldn't be that difficult either. The sandbox needs
> > > to install a mount namespace that only allows read access to Emacs's
> > > installation directory plus any input file and write access to known
> > > output files, and enable syscall filters that forbid everything except
> > > a list of known-safe syscalls (especially exec). I can take a stab at
> > > that, but I can't promise anything ;-)
> >
> > Looking forward to it.
> >
>
> I've looked into this, and what I'd suggest for now is:
> 1. Add a --seccomp=FILE command-line option that loads seccomp filters
> from FILE and applies them directly after startup (first thing in
> main). Why do this in Emacs? Because that's the easiest way to prevent
> execve. When installing a seccomp filter in a separate process, execve
> needs to be allowed because otherwise there'd be no way to execute the
> Emacs binary. While there are workarounds (ptrace, LD_PRELOAD), it's
> easiest to install the seccomp filter directly in the Emacs process.

I've attached a patch for this.

0001-Add-support-for-seccomp-command-line-option.patch
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