Messages in this thread | | | Date | Sun, 29 Aug 2004 22:43:55 +0400 | From | Alex Zarochentsev <> | Subject | Re: silent semantic changes with reiser4 |
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On Thu, Aug 26, 2004 at 06:13:03PM +0200, Christoph Hellwig wrote: > On Thu, Aug 26, 2004 at 05:06:38PM +0100, Jamie Lokier wrote: > > Christoph Hellwig wrote: > > > > There's bound to be some security issue, but I'm not sure what you're > > > > getting at with /tmp. What sort of sort of security problem arises > > > > with a world-writeable directory such as /tmp, that cannot arise with > > > > the standard fs semantics? > > > > > > Actually you are right on that issue because it would open the > > > device/fifo as directory and not device/fifo (in fact I'd had to look at > > > the code again to see whether they actually do this only for files or > > > also for special files) > > > > Are you saying that with reiser4, you can open a device or fifo with > > O_DIRECTORY? > > That's what I thought, but as far as I can follow the code this is not > actually true.
All reiser4 inodes have i_ops->lookup != NULL, so open(..., O_DIRECTORY) would succeed on them (thanks Nikita for reminding me that).
It may be better to pass the control of that to ->i_op->permission() through explicit MAY_LOOKUP flag. It can be possible to eliminate the race by some more complex logic (strict ownership check, for example) in ->permission().
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