On Tue, Aug 2, 2022 at 5:25 PM KP Singh <kpsingh@xxxxxxxxxx> wrote: > On Mon, Aug 1, 2022 at 5:19 PM Paul Moore <paul@xxxxxxxxxxxxxx> wrote: > > On Mon, Aug 1, 2022 at 9:13 AM Frederick Lawler <fred@xxxxxxxxxxxxxx> wrote: > > > On 7/22/22 7:20 AM, Paul Moore wrote: > > > > On July 22, 2022 2:12:03 AM Martin KaFai Lau <kafai@xxxxxx> wrote: > > > > > > > >> On Thu, Jul 21, 2022 at 12:28:04PM -0500, Frederick Lawler wrote: > > > >>> While creating a LSM BPF MAC policy to block user namespace creation, we > > > >>> used the LSM cred_prepare hook because that is the closest hook to prevent > > > >>> a call to create_user_ns(). > > > >>> > > > >>> The calls look something like this: > > > >>> > > > >>> cred = prepare_creds() > > > >>> security_prepare_creds() > > > >>> call_int_hook(cred_prepare, ... > > > >>> if (cred) > > > >>> create_user_ns(cred) > > > >>> > > > >>> We noticed that error codes were not propagated from this hook and > > > >>> introduced a patch [1] to propagate those errors. > > > >>> > > > >>> The discussion notes that security_prepare_creds() > > > >>> is not appropriate for MAC policies, and instead the hook is > > > >>> meant for LSM authors to prepare credentials for mutation. [2] > > > >>> > > > >>> Ultimately, we concluded that a better course of action is to introduce > > > >>> a new security hook for LSM authors. [3] > > > >>> > > > >>> This patch set first introduces a new security_create_user_ns() function > > > >>> and userns_create LSM hook, then marks the hook as sleepable in BPF. > > > >> Patch 1 and 4 still need review from the lsm/security side. > > > > > > > > This patchset is in my review queue and assuming everything checks out, I expect to merge it after the upcoming merge window closes. > > > > > > > > I would also need an ACK from the BPF LSM folks, but they're CC'd on this patchset. > > > > > > Based on last weeks comments, should I go ahead and put up v4 for > > > 5.20-rc1 when that drops, or do I need to wait for more feedback? > > > > In general it rarely hurts to make another revision, and I think > > you've gotten some decent feedback on this draft, especially around > > the BPF LSM tests; I think rebasing on Linus tree after the upcoming > > io_uring changes are merged would be a good idea. As I was typing up my reply I realized I mistakenly mentioned the io_uring changes that Linus just merged today - oops! If you haven't figured it out already, you can disregard that comment, that's a completely different problem and a completely different set of patches :) > > Although as a > > reminder to the BPF LSM folks - I'm looking at you KP Singh :) - I > > need an ACK from you guys before I merge the BPF related patches > > Apologies, I was on vacation. I am looking at the patches now. > Reviews and acks coming soon :) No worries, we've still got the two weeks of the merge window before I can do anything into linux-next - thanks KP! -- paul-moore.com
