Re: [RFC PATCH 1/4] lsm: separate security_task_getsecid() into subjective and objective variants

On Sun, Feb 21, 2021 at 7:51 AM John Johansen
[off-list ref] wrote:

On 2/19/21 3:29 PM, Paul Moore wrote:

quoted

Of the three LSMs that implement the security_task_getsecid() LSM
hook, all three LSMs provide the task's objective security
credentials.  This turns out to be unfortunate as most of the hook's
callers seem to expect the task's subjective credentials, although
a small handful of callers do correctly expect the objective
credentials.

This patch is the first step towards fixing the problem: it splits
the existing security_task_getsecid() hook into two variants, one
for the subjective creds, one for the objective creds.

  void security_task_getsecid_subj(struct task_struct *p,
                                 u32 *secid);
  void security_task_getsecid_obj(struct task_struct *p,
                                u32 *secid);

While this patch does fix all of the callers to use the correct
variant, in order to keep this patch focused on the callers and to
ease review, the LSMs continue to use the same implementation for
both hooks.  The net effect is that this patch should not change
the behavior of the kernel in any way, it will be up to the latter
LSM specific patches in this series to change the hook
implementations and return the correct credentials.

Signed-off-by: Paul Moore <paul@paul-moore.com>

So far this looks good. I want to take another stab at it and give
it some testing

Thanks John, I appreciate the extra set of eyes.  Let me know if you
run across anything wonky.

-- 
paul moore
www.paul-moore.com