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 ordering is no longer valid?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. _______________________________________________ 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.
