On Tue, Apr 11, 2017 at 9:54 PM, Casey Schaufler <casey@xxxxxxxxxxxxxxxx> wrote: > On 4/10/2017 9:43 PM, Kees Cook wrote: >> On Mon, Apr 10, 2017 at 1:00 PM, Djalal Harouni <tixxdz@xxxxxxxxx> wrote: >>> On Mon, Apr 10, 2017 at 9:26 PM, Casey Schaufler <casey@xxxxxxxxxxxxxxxx> wrote: >>>> I think that would be the prudent approach. There is still >>>> the possibility that blob sharing (or full stacking, if you >>>> prefer) won't be accepted any time soon. >>> Ok Casey! I will wait for more feedback, and if other maintainers do >>> not object, I will convert it back to rhashtables in next iterations >>> making sure that it should be simple to convert later to a blob >>> sharing mechanism. >> Would it be possible just to add a single field to task_struct if this >> LSM is built in? I feel like rhashtables is a huge overhead when a >> single field is all that's needed. > > Special casing the task_struct based on which modules > are compiled in would work, but I'm under the impression > that there's a strong desire to keep to one pointer for > security module information in the major structures. > > The code for generalizing shared blobs isn't that hard, > and y'all have seen it many times. It would be perfectly > safe to convert the task, cred, inode and such blobs to > be infrastructure managed right now. That wouldn't mean > that all the stacking issues (e.g. audit and networking) > would be addressed, or that all combinations of modules > would work (i.e. no SELinux+Smack) but it would clear > the way for this case. And Yama could use a blob if it > wanted to. I've been thinking about this again, so my patches did not convert creds, inodes etc, I don't have a use case for them now. My use case was for task->security and I re-used the simple approach. I can't offer a solution for other blobs since I'm not familiar with their context nor the different use cases. I checked TOMOYO and that was easy, but I can't check all of them. I agreed that I may use rhashtables but as Kees pointed out this may introduce overheads and extra memory, where the task->security for this ModAutoProtect LSM will only require an extra sizeof(unsigned long) per-task. Also again the problem is not in this proposed Module, the problem is in modules that can't be stacked together. I am bringing this, since maybe after we manage to merge this, and if Kees agree I may send another set of patches for Yama to enable the same per-task context, this enables containers but also allows later in systemd-logind sessions to set it where all inferiors inside the user sessions are protected by default, not only some apps or special desktops but for all. So I will hit the same problem again where to put it? You said that the code that generalize the blobs isn't that hard, but also in a previous response that it may not be accepted... so I will try to converge the task->security blob to be more like the infrastructure that you are proposing, then resubmit and maybe we will enable these modules that are stackable by default. Is this reasonable ? Thanks! -- tixxdz -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
