[v3,0/3] binder: use cred instead of task for security context

Message

Todd Kjos Oct. 6, 2021, 7:46 p.m. UTC

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