linux-kernel - [PATCH v3 0/3] binder: use cred instead of task for security context

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Date:   Wed,  6 Oct 2021 12:46:07 -0700
From:   Todd Kjos <tkjos@...gle.com>
To:     gregkh@...uxfoundation.org, arve@...roid.com, tkjos@...roid.com,
        maco@...roid.com, christian@...uner.io, jmorris@...ei.org,
        serge@...lyn.com, paul@...l-moore.com,
        stephen.smalley.work@...il.com, eparis@...isplace.org,
        keescook@...omium.org, jannh@...gle.com, jeffv@...gle.com,
        zohar@...ux.ibm.com, linux-security-module@...r.kernel.org,
        selinux@...r.kernel.org, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org
Cc:     joel@...lfernandes.org, kernel-team@...roid.com,
        Todd Kjos <tkjos@...gle.com>
Subject: [PATCH v3 0/3] binder: use cred instead of task for security context

This series fixes the possible use of an incorrect security context
when checking selinux permissions, getting a security ID, or lookup
up the euid.

The previous behavior was to save the group_leader 'struct task_struct'
in binder_open() and using that to obtain security IDs or euids.

This has been shown to be unreliable, so this series instead saves the
'struct cred' of the task that called binder_open(). This cred is used
for these lookups instead of the task.

v1 and v2 of this series were a single patch "binder: use euid from"
cred instead of using task". During review, Stephen Smalley identified
two more related issues so the corresponding patches were added to
the series.

Todd Kjos (3):
  binder: use cred instead of task for selinux checks
  binder: use cred instead of task for getsecid
  binder: use euid from cred instead of using task