On Tue, Oct 27, 2015 at 12:36 AM, Mimi Zohar <zo...@linux.vnet.ibm.com> wrote: > On Tue, 2015-10-27 at 00:03 +0200, Petko Manolov wrote: >> On 15-10-26 22:39:28, Dmitry Kasatkin wrote: > >> > Can you please still explain when multiple policy writers can content? I >> > 100% >> > understand the role of mutex.... >> >> Ignore the high level requirements for the moment. Every time you have a >> contended resource you need to protect it from concurrent writers. IMA >> policy >> is read way more frequently than it is been written. Just once in the past, >> now >> a few times more. > > Right. We all agree that only one process can append new rules at a > time. The open currently fails with -EBUSY. If the policy isn't being > updated frequently and there isn't any contention for writing the > policy, the question is why change the existing behavior (by defining a > new mutex)? > > Mimi >
Petko, I am exactly asking you about high-level... :) You do not need to explain to me that when there is contended resource it is necessary to protect it from concurrent writers. What I just ask is when we can get concurrent writers? I think system is updated by updating image or packages. In the first case policy update comes with the new image and loaded on reboot. in the second case, keys, policy and software comes with packages. Before new software (signed with new key) can be used, keys and policy needs to be loaded. The order is important - first keys, policy, then software can be installed and used. Packages are usually installed in ordered manner (not concurrently). Basically policy writing will happen also in ordered manner. So what I claim, is that there are no concurrent policy writers. Or I am totally wrong? -- Thanks, Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
