Messages in this thread | | | Date | Sun, 02 Mar 2003 15:16:21 +0100 | From | Kasper Dupont <> | Subject | Re: About /etc/mtab and /proc/mounts |
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DervishD wrote: > > If 'mount' treats specially the > mtab if it is a symlink... well, IMHO this is not correct. Yes, this > can lead to an attack, but: 'mount' is a setuid program, and only > root can symlink /etc/mtab, true?
The reason for mount not to update /etc/mtab if it is a symlink is not security concerns, but rather that it could be a symlink to /proc/mounts. Another problem is the way the update is actually done. A lockfile named /etc/mtab~ is created, and a new mtab is written to /etc/mtab.tmp which is later renamed on top of mtab.
Some of this can obviously be solved by changing mount. But if we are going to change mount in non-trivial ways, we should aim for a better longterm solution. It would be possible for mount to start from /et/mtab and use readlink until the actual location is found. Then if the path starts with /proc/ the update can be skipped, or done in a different way. And if the location is outside /proc then create lockfilename and tempfilename by appending to this path.
But all that is IMHO a bad solution. Getting the actual location right is nontrivial. And we should rather aim for an implementation in /proc and have mount write there directly. But there are a few open questions I'd like answered before trying to implement a /proc/mtab.
-- Kasper Dupont -- der bruger for meget tid på usenet. For sending spam use mailto:aaarep@daimi.au.dk for(_=52;_;(_%5)||(_/=5),(_%5)&&(_-=2))putchar(_); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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