>> >I assume you're talking about this kind of situation: >> > >> >mount --bind /local/writable/dir /chroot/untrusted/area/ >> >mount --o remount,ro /chroot/untrusted/area/ >> >> Well, actually about some kind of VPS: openvz or something like that. >> But yes, this is the same kind of scenario. > >yes, Linux-VServer provides this kind of ro --bind mounts >without the race, as the the flags are passed on the actual >mount > >> >This has no r/w window in the chroot area: >> > >> >mount --bind /local/writable/dir /tmp/area/ >> >mount --o remount,ro /tmp/area/ >> >mount --bind /tmp/area/ /chroot/untrusted/area/ >> >umount /tmp/area/ >> >> Well, it looks a little scarry and complicated at first. And probably >> requires you to know that semantic of --bind lets you do the last >> unmount. But if you are saying that this makes kernel smaller, faster >> and less buggy then you are probably very right. > >well, it makes the kernel more consistant in it's behaviour, >because especially for --rbind mounts, the logic what is >changed where and when is not as well defined as one would >wish ... > >btw, you could get the same result by simply doing: > >mount --bind /local/writable/dir /tmp/area/ >mount --o remount,ro /tmp/area/ >mount --move /tmp/area/ /chroot/untrusted/area/ > Just a nitpick, you all use "--o" ... :) mount: option `--o' is ambiguous Jan Engelhardt -- - 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
