Re: [PATCH 0/4 POC] Allow executing code and syscalls in another address space

[Johannes Berg <johannes@sipsolutions.net>]

On Wed, 2021-04-14 at 08:22 +0100, Anton Ivanov wrote:
> On 14/04/2021 06:52, Andrei Vagin wrote:
> > We already have process_vm_readv and process_vm_writev to read and write
> > to a process memory faster than we can do this with ptrace. And now it
> > is time for process_vm_exec that allows executing code in an address
> > space of another process. We can do this with ptrace but it is much
> > slower.
> > 
> > = Use-cases =
> > 
> > Here are two known use-cases. The first one is “application kernel”
> > sandboxes like User-mode Linux and gVisor. In this case, we have a
> > process that runs the sandbox kernel and a set of stub processes that
> > are used to manage guest address spaces. Guest code is executed in the
> > context of stub processes but all system calls are intercepted and
> > handled in the sandbox kernel. Right now, these sort of sandboxes use
> > PTRACE_SYSEMU to trap system calls, but the process_vm_exec can
> > significantly speed them up.
> 
> Certainly interesting, but will require um to rework most of its memory 
> management and we will most likely need extra mm support to make use of 
> it in UML. We are not likely to get away just with one syscall there.

Might help the seccomp mode though:

https://patchwork.ozlabs.org/project/linux-um/list/?series=231980

johannes