Messages in this thread | | | Date | Thu, 14 Feb 2013 16:44:45 -0500 | From | Vivek Goyal <> | Subject | Re: [RFC PATCH 0/6][v3] ima: Support a mode to appraise signed files only |
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On Thu, Feb 14, 2013 at 03:51:24PM -0500, Mimi Zohar wrote: > On Thu, 2013-02-14 at 14:55 -0500, Vivek Goyal wrote: > > Hi, > > > > Currently ima appraises all the files as specified by the rule. > > Currently IMA appraises files based on policy.
And policy is composed of multiple rules. Ok, will change it.
> > > So > > if one wants to create a system where only few executables are > > signed, that system will not work with IMA. > > This statement misrepresents the IMA policy. You can definitely define > a policy that only measures/appraises a few specific files. In your > usecase scenario, you are not willing to rely on LSM labels. Policy > rules can also be based on file owner. We could also add support for > gid.
Ok, will change it. How about following.
We want to create a system where only few executables are signed. This patch extends IMA policy syntax so that one can specify that signatures are optional.
> > > With secureboot, one needs to disable kexec so that unsigned kernels > > can't be booted. To avoid this problem, it was proposed that sign > > /sbin/kexec binary and if signatures are verified successfully, give > > an special capability to the /sbin/kexec process. And in secureboot > > mode processes with that special capability can invoke sys_kexec() > > system call. > > Please add here that you then rely on /sbin/kexec to verify the > integrity of the kernel image.
Ok, will do that. This is infact a grey area. Yet to be figured out how /sbin/kexec will ensure a signed kernel is being loaded.
Thanks Vivek
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