On 05/11/2015 10:02 AM, Stephen Smalley wrote: > On 05/11/2015 09:49 AM, Petr Lautrbach wrote: >> On 05/11/2015 03:43 PM, Stephen Smalley wrote: >>> On 05/11/2015 09:40 AM, Petr Lautrbach wrote: >>>> On 04/17/2015 03:42 PM, Stephen Smalley wrote: >>>>> SELinux can be disabled via the selinux=0 kernel parameter or via >>>>> /sys/fs/selinux/disable (triggered by setting SELINUX=disabled in >>>>> /etc/selinux/config). In either case, selinuxfs will be unmounted >>>>> and unregistered and therefore it is sufficient to check for the >>>>> selinuxfs mount. We do not need to check for no-policy-loaded and >>>>> treat that as SELinux-disabled anymore; that is a relic of Fedora Core 2 >>>>> days. Drop the no-policy-loaded test, which was a bit of a hack anyway >>>>> (checking whether getcon_raw() returned "kernel" as that can only happen >>>>> if no policy is yet loaded and therefore security_sid_to_context() only >>>>> has the initial SID name available to return as the context). >>>>> >>>>> May possibly fix https://bugzilla.redhat.com/show_bug.cgi?id=1195074 >>>>> by virtue of removing the call to getcon_raw() and therefore avoiding >>>>> use of tls on is_selinux_enabled() calls. Regardless, it will make >>>>> is_selinux_enabled() faster and simpler. >>>>> >>>> >>>> This patch breaks system with SELinux enabled kernel and without >>>> loaded/installed an SELinux policy, see [1]. >>>> >>>> Would it be feasible to have is_selinux_enabled() connected to existence >>>> of SELINUX variable in /etc/selinux/config file for the cases when >>>> there's no specific kernel command line option used in running system? >>>> Or would it break something else? >>>> >>>> [1] https://bugzilla.redhat.com/show_bug.cgi?id=1219045 >>> >>> Sorry, does this occur even if they have SELINUX=disabled in >>> /etc/selinux/config? >> >> It works with SELINUX=disabled. It's only related to systems without >> /etc/selinux/config and without selinux=0 on kernel command line. > > I see. So I can see that it is a regression for such systems, but such > systems are definitely running suboptimally by NOT disabling SELinux if > they are not going to even load a policy. They are just wasting all of > the SELinux hook call overhead in the kernel. > > In any event, one of the benefits of the change that caused this > regression is that it makes is_selinux_enabled() very fast and avoids > any need to open any extra files on calls to it, thereby improving > performance on both SELinux-enabled and SELinux-disabled systems. > > I don't think we need or want to actually have it read > /etc/selinux/config and look for a SELINUX= variable. Isn't it > sufficient to test for the existence of an /etc/selinux/config file, > e.g. access("/etc/selinux/config", F_OK)? > > We'll have to wrap that test with #ifndef ANDROID as Android does not > use /etc/selinux/config. Oh, and let's do it once in init_selinuxmnt() and cache the result so we aren't calling access() on each is_selinux_enabled() call. _______________________________________________ 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.
