On Tue, 2011-03-15 at 19:08 +0300, Vasiliy Kulikov wrote: > On Tue, Mar 15, 2011 at 07:50 -0400, James Bottomley wrote: > > 1. Did anyone actually check for capabilities before assuming world > > writeable files were wrong? > > I didn't check all these files as I haven't got these hardware :-) You don't need the hardware to check ... the question becomes is a capabilities test sitting in the implementation or not. > But > as I can "chmod a+w" all sysfs files on my machine and they all become > sensible to nonroot writes, I suppose there is nothing preventing > nonroot users from writing to these buggy sysfs files. As you can see, > there are no capable() checks in these drivers in open() or write(). > > > 2. Even if there aren't any capabilities checks in the implementing > > routines, should there be (are we going the separated > > capabilities route vs the monolithic root route)? > > IMO, In any case old good DAC security model must not be obsoleted just > because someone thinks that MAC or anything else is more convenient for > him. If sysfs is implemented via filesystem then it must support POSIX > permissions semantic. MAC is very good in _some_ cases, but not instead > of DAC. Um, I'm not sure that's even an issue. capabilities have CAP_ADMIN which is precisely the same check as owner == root. We use this a lot because ioctls ignore the standard unix DAC model. James -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
