Quoting Miklos Szeredi (miklos@xxxxxxxxxx): > > > > > > 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. > > > > > > That depends. Current patches check the "unprivileged submounts > > > allowed under this mount" flag only on the requested mount and not on > > > the propagated mounts. Do you see a problem with this? > > > > Don't see a problem if the flag is propagated to all peers and slave > > mounts. > > > > If not, I see a problem. What if the propagated mount has its flag set > > to not do un-priviledged mounts, whereas the requested mount has it > > allowed? > > Then the mount is allowed. > > It is up to the sysadmin/distro to design set up the propagations in a > way that this is not a problem. > > I think it would be much less clear conceptually, if unprivileged > mounting would have to check propagations as well. > > Miklos I'm a bit lost about what is currently done and who advocates for what. It seems to me the MNT_ALLOWUSERMNT (or whatever :) flag should be propagated. In the /share rbind+chroot example, I assume the admin would start by doing mount --bind /share /share mount --make-slave /share mount --bind -o allow_user_mounts /share (or whatever) mount --make-shared /share then on login, pam does chroot /share/$USER or some sort of mount --bind /share /home/$USER/root chroot /home/$USER/root or whatever. In any case, the user cannot make user mounts except under /share, and any cloned namespaces will still allow user mounts. Or are you guys talking about something else? -serge - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
