On Mon, 2013-01-28 at 15:22 -0500, Vivek Goyal wrote: > On Mon, Jan 28, 2013 at 03:15:49PM -0500, Mimi Zohar wrote: > > On Mon, 2013-01-28 at 13:56 -0500, Vivek Goyal wrote: > > > On Mon, Jan 28, 2013 at 05:20:20PM +0200, Kasatkin, Dmitry wrote: > > > > > > [..] > > > > > Ok. I am hoping that it will be more than the kernel command line we > > > > > support. In the sense that for digital signatures one needs to parse > > > > > the signature, look at what hash algorithm has been used and then > > > > > collect the hash accordingly. It is little different then IMA requirement > > > > > of calculating one pre-determine hash for all files. > > > > > > > > Yes... It is obvious. It's coming. > > > > But in general, signer should be aware of requirements and limitation > > > > of the platform. > > > > It is not really a problem... > > > > > > One more question. I specified "ima_appraise_tcb" on kernel command line > > > and I had an unbootable system. It refused to run "init" as it was not > > > labeled/signed. Is there any policy/way where it appraises only signed > > > files and does not refuse to open/execute unsigned ones. > > > > The policy defines what needs to be measured/appraised, not the other > > way around. There's nothing preventing you from defining and loading a > > different policy, one to your liking, before pivoting root. > > Hi Mimi, > > By policy you mean ima rules here? So I can either enable default rules > (tcb default rules for appraisal and measurement) by using kernel command > line options or dynamically configure my own rules using /sysfs interface? > > If yes, AFAIK, existing inputtable policies do not allow this selective > mode where we do appraisal only on signed executable. That means I shall > have to extend the way policies can be specified so that one specify > that appraise only signed files? We've just added the ability of defining the method for appraising a file and defining rules in terms of the filesystem UUID. Extending the IMA policy shouldn't be a problem, but I'm not sure how you would go about adding support for only appraising files with digital signatures. > Also given the fact that we allow loading policy from initramfs, root > can rebuild initramfs and change the policy which takes effect over next > reboot. So in priciple this works only when we are trying to impose some > policy on non-root users? The assumption has always been that the initramfs would be measured, for trusted boot, and appraised, for secure boot, before being executed. Mimi -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
