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Date:   Wed,  6 Oct 2021 17:46:29 -0700
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Subject: [PATCH v4 3/3] binder: use euid from cred instead of using task
From:   Todd Kjos <tkjos@google.com>
To:     gregkh@linuxfoundation.org, arve@android.com, tkjos@android.com,
        maco@android.com, christian@brauner.io, jmorris@namei.org,
        serge@hallyn.com, paul@paul-moore.com,
        stephen.smalley.work@gmail.com, eparis@parisplace.org,
        keescook@chromium.org, jannh@google.com, jeffv@google.com,
        zohar@linux.ibm.com, linux-security-module@vger.kernel.org,
        selinux@vger.kernel.org, devel@driverdev.osuosl.org,
        linux-kernel@vger.kernel.org
Cc:     joel@joelfernandes.org, kernel-team@android.com,
        Todd Kjos <tkjos@google.com>, stable@vger.kernel.org
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Precedence: bulk

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.

Fixes: 457b9a6f09f0 ("Staging: android: add binder driver")
Signed-off-by: Todd Kjos <tkjos@google.com>
Suggested-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Cc: stable@vger.kernel.org # 4.4+
---
v3: added this patch to series

 drivers/android/binder.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 989afd0804ca..26382e982c5e 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2711,7 +2711,7 @@ static void binder_transaction(struct binder_proc *proc,
 		t->from = thread;
 	else
 		t->from = NULL;
-	t->sender_euid = task_euid(proc->tsk);
+	t->sender_euid = proc->cred->euid;
 	t->to_proc = target_proc;
 	t->to_thread = target_thread;
 	t->code = tr->code;
-- 
2.33.0.800.g4c38ced690-goog