On 8/1/2022 6:13 AM, Frederick Lawler 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? As the primary consumer of this hook is BPF I would really expect their reviewed-by before accepting this. > >> -- >> paul-moore.com >> >> >
