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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 371CDC433EF for ; Tue, 9 Nov 2021 07:23:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 18A1161175 for ; Tue, 9 Nov 2021 07:23:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241044AbhKIH0B (ORCPT ); Tue, 9 Nov 2021 02:26:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:41290 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240071AbhKIH0B (ORCPT ); Tue, 9 Nov 2021 02:26:01 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 563FE61165; Tue, 9 Nov 2021 07:23:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1636442595; bh=FRY2NeBGnnZzYkxzAdi6/EjK3XgLR0VWkM9LRaCd/g4=; h=Subject:To:Cc:From:Date:From; b=jKGlbcBJZNQlKtFllYjeFw97QatT1DBsrXfctJcaiGJdulHLZGsvHaD+yj9rbG5Qf i+Sa21u+TEWSlouKasVEGPm6i3hpP334bdEJoYU70TMR/eTFvAWmiJ8TIbsotATdqh NT11rG+eH4qcxs2VJb1jItDLmDH1JPjeamjrAfIk= Subject: FAILED: patch "[PATCH] binder: use euid from cred instead of using task" failed to apply to 4.19-stable tree To: tkjos@google.com, casey@schaufler-ca.com, jannh@google.com, paul@paul-moore.com, stephen.smalley.work@gmail.com Cc: From: Date: Tue, 09 Nov 2021 08:23:03 +0100 Message-ID: <1636442583229101@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 29bc22ac5e5bc63275e850f0c8fc549e3d0e306b Mon Sep 17 00:00:00 2001 From: Todd Kjos Date: Tue, 12 Oct 2021 09:56:12 -0700 Subject: [PATCH] binder: use euid from cred instead of using task 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 diff --git a/drivers/android/binder.c b/drivers/android/binder.c index d9030cb6b1e4..231cff9b3b75 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -2702,7 +2702,7 @@ 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; @@ -4343,6 +4343,7 @@ static void binder_free_proc(struct binder_proc *proc) } binder_alloc_deferred_release(&proc->alloc); put_task_struct(proc->tsk); + put_cred(proc->cred); binder_stats_deleted(BINDER_STAT_PROC); kfree(proc); } @@ -5021,6 +5022,7 @@ static int binder_open(struct inode *nodp, struct file *filp) spin_lock_init(&proc->outer_lock); get_task_struct(current->group_leader); proc->tsk = current->group_leader; + proc->cred = get_cred(filp->f_cred); INIT_LIST_HEAD(&proc->todo); init_waitqueue_head(&proc->freeze_wait); proc->default_priority = task_nice(current); diff --git a/drivers/android/binder_internal.h b/drivers/android/binder_internal.h index 810c0b84d3f8..e7d4920b3368 100644 --- a/drivers/android/binder_internal.h +++ b/drivers/android/binder_internal.h @@ -364,6 +364,9 @@ struct binder_ref { * (invariant after initialized) * @tsk task_struct for group_leader of process * (invariant after initialized) + * @cred struct cred associated with the `struct file` + * in binder_open() + * (invariant after initialized) * @deferred_work_node: element for binder_deferred_list * (protected by binder_deferred_lock) * @deferred_work: bitmap of deferred work to perform @@ -424,6 +427,7 @@ struct binder_proc { struct list_head waiting_threads; int pid; struct task_struct *tsk; + const struct cred *cred; struct hlist_node deferred_work_node; int deferred_work; int outstanding_txns;