On Thu, 2013-02-14 at 10:03 -0500, Vivek Goyal wrote: > On Wed, Feb 13, 2013 at 05:27:01PM -0500, Mimi Zohar wrote: > > [..] > > > Yep, I got that. Default policy gets overruled when a new policy is > > > loaded. > > > > > > In secureboot mode, somehow above rule needs to take effect by default. > > > One option would be that kernel can enforce above rule. > > > (I guess by adding it to both default_list as well as policy list). > > > > The default policy is empty, but can be replaced with boot command line > > options. The existing options are ima_tcb and/ ima_appraise_tcb. > > Please feel free to define an additional policy. > > I think just defining a new command line option is not sufficient > for secureboot use case. > > - One can easily remove kernel command line option without breaking > booting and easily bypass secureboot restrictions.
> - I guess this is one mandated rule by secureboot. There might still > be a user policy which can co-exist with this rule. > > So to me this is not a new policy. It is just one mandatory rule which > gets appended to any policy in secureboot mode. Think of it as mandatory > rule imposed by kernel for any policy user can define. And in secureboot > mode a user can not get rid of this rule. (Otherwise it breaks user > space signing and one can bypass secureboot and boot into unsigned > kernel). Your rule allows both signed and unsigned files to be executed. Signed files will just have more capabilities. The ima_appraise_tcb option requires all files owned by root to be signed, otherwise access is denied. The two policies simply can not co-exist. How about defining your single rule as ima_secureboot and making it the default policy. Only if ima_appraise_tcb is specified on the kernel command line, will the default policy be replaced. This type of change, going from a null policy to an ima_secureboot policy, would require community approval. thanks, Mimi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
