On Fri, May 22, 2020 at 09:53:31AM +0200, Christian Brauner wrote: > On Fri, May 22, 2020 at 07:53:50AM +0200, Adrian Reber wrote: > > > > There are probably a few more things guarded by CAP_SYS_ADMIN required > > to run checkpoint/restore as non-root, but by applying this patch I can > > already checkpoint and restore processes as non-root. As there are > > already multiple workarounds I would prefer to do it correctly in the > > kernel to avoid that CRIU users are starting to invent more workarounds. > > It sounds ok to me as long as this feature is guarded by any sensible > capability. I don't want users to be able to randomly choose their pid > without any capability required. > > We've heard the plea for unprivileged checkpoint/restore through the > grapevine and a few times about CAP_RESTORE at plumbers but it's one of > those cases where nobody pushed for it so it's urgency was questionable. > This is 5.9 material though and could you please add selftests? > > It also seems you have future changes planned that would make certain > things accessible via CAP_RESTORE that are currently guarded by other > capabilities. Any specific things in mind? It might be worth knowing > what we'd be getting ourselves into if you're planning on flipping > switches in other places. /proc/pid/map_files is one of the first candidate what we need to think about. CRIU opens files from /proc/pid/map_files to dump file mappings, shared memory mappings, memfd files. Right now, it is impossible to open these files without CAP_SYS_ADMIN in the root user-namespace (proc_map_files_get_link).
