On 02/27/2014 11:26 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 ordering is no longer valid?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. Wouldn't removing mmap_zero be contrary to SELinux having fine-grained access controls, since CAP_SYS_RAWIO is broader than this specific case? -- Chris PeBenito Tresys Technology, LLC www.tresys.com | oss.tresys.com _______________________________________________ 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.
