From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E972C43219 for ; Wed, 24 Nov 2021 12:16:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243602AbhKXMSg (ORCPT ); Wed, 24 Nov 2021 07:18:36 -0500 Received: from mail.kernel.org ([198.145.29.99]:48022 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242978AbhKXMNP (ORCPT ); Wed, 24 Nov 2021 07:13:15 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1F44B61101; Wed, 24 Nov 2021 12:07:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1637755649; bh=g9CVlPlILTGS9BVDOEUMb9P/3PmB6ASZv1w9+5iziP4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QJcd1AH0JIpgObG1M8VKJ/ofvRFOLwqqoFnaN9L8o94//Ct7pjvoDog0vvJrZF2Ju yI61Rix1iqxKZUkblbU/JJ+YRUH1xbKLlCHQy+e0Vt02t0fNNw8Fq9g+3KoGBCkfpG JxH4bvcesGDGMpKKBEvd6LNb32sb9ySaDaTonjbg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Todd Kjos , Stephen Smalley , Jann Horn , Casey Schaufler , Paul Moore Subject: [PATCH 4.9 001/207] binder: use euid from cred instead of using task Date: Wed, 24 Nov 2021 12:54:32 +0100 Message-Id: <20211124115703.989947149@linuxfoundation.org> X-Mailer: git-send-email 2.34.0 In-Reply-To: <20211124115703.941380739@linuxfoundation.org> References: <20211124115703.941380739@linuxfoundation.org> User-Agent: quilt/0.66 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Todd Kjos 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 Suggested-by: Stephen Smalley Suggested-by: Jann Horn Acked-by: Casey Schaufler Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -303,6 +303,7 @@ struct binder_proc { struct task_struct *tsk; struct files_struct *files; struct mutex files_lock; + const struct cred *cred; struct hlist_node deferred_work_node; int deferred_work; void *buffer; @@ -1505,7 +1506,7 @@ static void binder_transaction(struct bi 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; @@ -3036,6 +3037,7 @@ static int binder_open(struct inode *nod get_task_struct(current->group_leader); proc->tsk = current->group_leader; mutex_init(&proc->files_lock); + proc->cred = get_cred(filp->f_cred); INIT_LIST_HEAD(&proc->todo); init_waitqueue_head(&proc->wait); proc->default_priority = task_nice(current); @@ -3241,6 +3243,7 @@ static void binder_deferred_release(stru } put_task_struct(proc->tsk); + put_cred(proc->cred); binder_debug(BINDER_DEBUG_OPEN_CLOSE, "%s: %d threads %d, nodes %d (ref %d), refs %d, active transactions %d, buffers %d, pages %d\n",