binder: use euid from cred instead of using task
authorTodd Kjos <tkjos@google.com>
Tue, 12 Oct 2021 16:56:12 +0000 (09:56 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 12 Nov 2021 14:05:48 +0000 (15:05 +0100)
commitff1bd01f490ba60d82c765100d95d13cc00c1625
tree42690c64444da23626052c777abb61b5f9ee0702
parentec7c20d417145449e992e549e17a015364a6c47d
binder: use euid from cred instead of using task

commit 29bc22ac5e5bc63275e850f0c8fc549e3d0e306b upstream.

Save the 'struct cred' associated with a binder process
at initial open to avoid potential race conditions
when converting to an euid.

Set a transaction's sender_euid from the 'struct cred'
saved at binder_open() instead of looking up the euid
from the binder proc's 'struct task'. This ensures
the euid is associated with the security context that
of the task that opened binder.

Cc: stable@vger.kernel.org # 4.4+
Fixes: 457b9a6f09f0 ("Staging: android: add binder driver")
Signed-off-by: Todd Kjos <tkjos@google.com>
Suggested-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Suggested-by: Jann Horn <jannh@google.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/android/binder.c
drivers/android/binder_internal.h