Re: Re: [patch 05/10] add "permit user mounts in new namespace" clone flag
> > "Serge E. Hallyn" <serue@us.ibm.com> writes: > > > Quoting Miklos Szeredi (miklos@szeredi.hu): > >> From: Miklos Szeredi <mszeredi@suse.cz> > >> > >> If CLONE_NEWNS and CLONE_NEWNS_USERMNT are given to clone(2) or > >> unshare(2), then allow user mounts within the new namespace. > >> > >> This is not flexible enough, because user mounts can't be enabled > for > >> the initial namespace. > >> > >> The remaining clone bits also getting dangerously few... > >> > >> Alternatives are: > >> > >> - prctl() flag > >> - setting through the containers filesystem > > > > Sorry, I know I had mentioned it, but this is definately my least > > favorite approach. > > > > Curious whether are any other suggestions/opinions from the > containers > > list? > > Given the existence of shared subtrees allowing/denying this at the > mount > namespace level is silly and wrong. > > If we need more than just the filesystem permission checks can we > make it a mount flag settable with mount and remount that allows > non-privileged users the ability to create mount points under it > in directories they have full read/write access to. Also for bind-mount and remount operations the flag has to be propagated down its propagation tree. Otherwise a unpriviledged mount in a shared mount wont get reflected in its peers and slaves, leading to unidentical shared-subtrees. RP > > I don't like the use of clone flags for this purpose but in this > case the shared subtress are a much more fundamental reasons for not > doing this at the namespace level. > > Eric > _______________________________________________ > Containers mailing list > Containers@lists.linux-foundation.org > https://lists.linux-foundation.org/mailman/listinfo/containe rs
> > Given the existence of shared subtrees allowing/denying this at the > > mount > > namespace level is silly and wrong. > > > > If we need more than just the filesystem permission checks can we > > make it a mount flag settable with mount and remount that allows > > non-privileged users the ability to create mount points under it > > in directories they have full read/write access to. > > Also for bind-mount and remount operations the flag has to be propagated > down its propagation tree. Otherwise a unpriviledged mount in a shared > mount wont get reflected in its peers and slaves, leading to unidentical > shared-subtrees. That's an interesting question. Do we want shared mounts to be totally identical, including mnt_flags? It doesn't look as if do_remount() guarantees that currently. Miklos
On Mon, 2007-04-16 at 11:32 +0200, Miklos Szeredi wrote: > > > Given the existence of shared subtrees allowing/denying this at the > > > mount > > > namespace level is silly and wrong. > > > > > > If we need more than just the filesystem permission checks can we > > > make it a mount flag settable with mount and remount that allows > > > non-privileged users the ability to create mount points under it > > > in directories they have full read/write access to. > > > > Also for bind-mount and remount operations the flag has to be propagated > > down its propagation tree. Otherwise a unpriviledged mount in a shared > > mount wont get reflected in its peers and slaves, leading to unidentical > > shared-subtrees. > > That's an interesting question. Do we want shared mounts to be > totally identical, including mnt_flags? It doesn't look as if > do_remount() guarantees that currently. Depends on the semantics of each of the flags. Some flags like of the read/write flag, would not interfere with the propagation semantics AFAICT. But this one certainly seems to interfere. RP > Miklos