On Thursday, February 27, 2014 11:26:35 AM Stephen Smalley wrote: > On 02/27/2014 11:22 AM, Paul Moore wrote: > > On Thursday, February 27, 2014 10:57:46 AM Stephen Smalley wrote: > >> On 02/27/2014 09:30 AM, Paul Moore wrote: > >>> It turns out that doing the SELinux MAC checks for mmap() before the > >>> DAC checks was causing users and the SELinux policy folks headaches > >>> as users were seeing a lot of SELinux AVC denials for the > >>> memprotect:mmap_zero permission that would have also been denied by > >>> the normal DAC capability checks (CAP_SYS_RAWIO). > >> > >> So you think that the explanation given in the comment for the current > >> ordering is no longer valid? > > > > Yes and no. Arguably there is still some value in it but there are enough > > problems with it as-is that I think the value is starting to be outweighed > > by the pain it is causing (Dan can be very annoying when he wants > > something <g>). For those users who still want notification of processes > > trying to mmap() low addresses, I think an audit watch is a much better > > approach. I don't think SELinux shouldn't be acting as an intrustion > > detection tool when we have other things that do that job. > > > > Let's also not forget that the MAC-before-DAC approach goes against the > > general approach to applying SELinux controls, so there is some argument > > to be had for consistency as well. > > > > Do you have a strong objection to this patch? > > No, although I do wonder if we ought to just dispense with mmap_zero > altogether at this point. It made sense when there was no capability > check or if the capability was one of the extremely broad ones (e.g. > CAP_SYS_ADMIN), but I don't really see why we can't be just as > restrictive with CAP_SYS_RAWIO / sys_rawio as with mmap_zero. Seems like a reasonable argument to me. I pinged Eric to get his thoughts on the issue since he added the check originally; if he is okay with removing it, I'll go ahead do it. -- paul moore security and virtualization @ redhat _______________________________________________ Selinux mailing list Selinux@xxxxxxxxxxxxx To unsubscribe, send email to Selinux-leave@xxxxxxxxxxxxx. To get help, send an email containing "help" to Selinux-request@xxxxxxxxxxxxx.
