For the record here is the lkml post https://lkml.org/lkml/2023/10/28/155 Edouard Klein <e...@rdklein.fr> writes:
> Thanks Moody for the nudge in a direction I hadn't explored. > > It seems that Linux does not see 9p as been safe to mount without > privilege. From what I understand, only FS with the FS_USERNS_MOUNT flag > can be mounted in a user namespace. It seems that v9fs is not one of > them: > > For example, tmpfs is a safe FS, and I can do: > unshare --user --map-root-user --mount > mount -t tmpfs tmpfs mnt/mnt1/ > > and it works. > > However, if I do: > unshare --user --map-root-user --mount > mount -t 9p -o trans=unix /run/9p/srv4 mnt/mnt1 > > I get mount: /home/edouard/mnt/mnt1: permission denied. > > > I've sent an email to the linux kernel mailing list to see if somebody > there has any up to date information. > > Somebody tried the same thing in 2018: > https://lore.kernel.org/all/39b08c53-3449-3164-c1b1-44ac587dd...@metux.net/T/ > Seemingly without succeeding. > > The end of the above thread is a bit worrying: >> plan9fs would >> also be a candidate for that kind of treatment if it had a maintainer. > > I did not know v9fs was unmaintained, I find that a bit surprising. It > does work very reliably. > > I'll keep this list updated as I make progress. > > Cheers, > > Edouard > > mo...@posixcafe.org writes: > >> Edouard, >> >> I am no Linux expert, but I think if you create a mount namespace as part of >> the user namespace you will be allowed to execute mounts without root. In >> terms of clients, I am not aware >> of any other then the one within the linux kernel. >> >> Regards, >> Moody >> 9fans / 9fans / see discussions + participants + delivery options Permalink ------------------------------------------ 9fans: 9fans Permalink: https://9fans.topicbox.com/groups/9fans/Tb5d039f675c54046-Mf8b4d705299aeeb3bc919867 Delivery options: https://9fans.topicbox.com/groups/9fans/subscription
