From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from frasgout13.his.huawei.com (frasgout13.his.huawei.com [14.137.139.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EFC661DB342; Mon, 7 Oct 2024 16:49:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=14.137.139.46 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728319786; cv=none; b=cNvavw+TaDk2BlSWxDgF/TINCQqGBRxlxvJVDj04i0mqoswMhGDyl3CMkcOdJili1JveqCHHsa+Ggr2a823v7uoA/0yYjSmwHFrV8VLKaNZYh+eR1lHFRisA/mxnZqeWH/pi7+OMkQ3gkG1+qPOHwTE5D8QaW1c1Hp3t2z8kVQU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728319786; c=relaxed/simple; bh=e6oL7ZRUZC32HjR14NFb3QSMDDEUolhQktq5ahOdaFU=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=GWrHM+rt7Wy9uDaT9/41gXbq/XCZ2eLdZqm/dzxvn9ZtmUzzlEqbYYDXqj96iNsmf7PicIEzuo4b3+G24ivhQBarq30gF7b32S+u/Pa8czXwC0lmMOPYX+M57YtqlxZg7bZddv8VwmsI2yyKw6d+4DUlOlBuaYP2/PLMG1UDS+8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=14.137.139.46 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.18.186.29]) by frasgout13.his.huawei.com (SkyGuard) with ESMTP id 4XMl3m3dKzz9v7NS; Tue, 8 Oct 2024 00:29:40 +0800 (CST) Received: from mail02.huawei.com (unknown [7.182.16.27]) by mail.maildlp.com (Postfix) with ESMTP id DBD1A140516; Tue, 8 Oct 2024 00:49:29 +0800 (CST) Received: from [127.0.0.1] (unknown [10.204.63.22]) by APP2 (Coremail) with SMTP id GxC2BwDXOMkOEQRnSZ5qAg--.56494S2; Mon, 07 Oct 2024 17:49:29 +0100 (CET) Message-ID: <70f55efdba0e682907c895ea8ba537ea435bc3aa.camel@huaweicloud.com> Subject: Re: [syzbot] [integrity?] [lsm?] possible deadlock in process_measurement (4) From: Roberto Sassu To: Paul Moore Cc: Shu Han , syzbot , akpm@linux-foundation.org, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, hughd@google.com, jmorris@namei.org, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, roberto.sassu@huawei.com, serge@hallyn.com, stephen.smalley.work@gmail.com, syzkaller-bugs@googlegroups.com, zohar@linux.ibm.com Date: Mon, 07 Oct 2024 18:49:15 +0200 In-Reply-To: References: <66f7b10e.050a0220.46d20.0036.GAE@google.com> <05e893036fa8753e0177db99dd48eb9d2e33476a.camel@huaweicloud.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.44.4-0ubuntu2 Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID:GxC2BwDXOMkOEQRnSZ5qAg--.56494S2 X-Coremail-Antispam: 1UD129KBjvJXoWxAF15Xw1xtryrCF4xZryfCrg_yoW5ury8pF 9agayIkr4ktFy7Arn2yr1UW3W0y34UKrWUWrZ5Jr18t3Z0vF1ktr17Jr1fuFyUGrZ5u34I qr4UWryfJ3WDArDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUv0b4IE77IF4wAFF20E14v26ryj6rWUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Jr0_JF4l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW8JVWxJwA2z4x0Y4vEx4A2jsIEc7CjxV AFwI0_Gr1j6F4UJwAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG 6I80ewAv7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFV Cjc4AY6r1j6r4UM4x0Y48IcVAKI48JM4IIrI8v6xkF7I0E8cxan2IY04v7MxkF7I0En4kS 14v26r4a6rW5MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I 8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVW8ZVWr XwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x 0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_ Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7IU0 s2-5UUUUU== X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAgAJBGcDQ-4OAAAEsc On Mon, 2024-10-07 at 12:35 -0400, Paul Moore wrote: > On Mon, Oct 7, 2024 at 11:31=E2=80=AFAM Roberto Sassu > wrote: > > On Wed, 2024-10-02 at 23:09 -0400, Paul Moore wrote: > > > On Sat, Sep 28, 2024 at 2:08=E2=80=AFPM Shu Han wrote: > > > >=20 > > > > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D > > > > > WARNING: possible circular locking dependency detected > > > > > 6.11.0-syzkaller-10045-g97d8894b6f4c #0 Not tainted > > > > > ------------------------------------------------------ > > > > > syz-executor369/5231 is trying to acquire lock: > > > > > ffff888072852370 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}, at: i= node_lock include/linux/fs.h:815 [inline] > > > > > ffff888072852370 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}, at: p= rocess_measurement+0x439/0x1fb0 security/integrity/ima/ima_main.c:250 > > > > >=20 > > > > > but task is already holding lock: > > > > > ffff88807ac9a798 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_loc= k_killable include/linux/mmap_lock.h:122 [inline] > > > > > ffff88807ac9a798 (&mm->mmap_lock){++++}-{3:3}, at: __do_sys_remap= _file_pages mm/mmap.c:1649 [inline] > > > > > ffff88807ac9a798 (&mm->mmap_lock){++++}-{3:3}, at: __se_sys_remap= _file_pages+0x22d/0xa50 mm/mmap.c:1624 > > > > >=20 > > > > > which lock already depends on the new lock. > > > >=20 > > > > This issue (if not a false positive?) is due to the possible `prot` > > > > change caused by the processing logic for READ_IMPLIES_EXEC in do_m= map(), > > > > so the remap_file_pages() must perform LSM check before calling do_= mmap(), > > > > this is what the previous commit want to do. > > >=20 > > > My apologies for the delay on this, I was traveling for a bit and > > > missed this issue while away. > > >=20 > > > Looking quickly at the report, I don't believe this is a false positi= ve. > > >=20 > > > > The LSM check is required to know what the `prot` is, but `prot` mu= st be > > > > obtained after holding the `mmap_write_lock`. > > > >=20 > > > > If the `mmap_write_lock` is released after getting the `prot` and b= efore > > > > the LSM call in remap_file_pages(), it may cause TOCTOU. > > >=20 > > > Looking at the IMA code, specifically the process_measurement() > > > function which is called from the security_mmap_file() LSM hook, I'm > > > not sure why there is the inode_lock() protected region. Mimi? > > > Roberto? My best guess is that locking the inode may have been > > > necessary before we moved the IMA inode state into the inode's LSM > > > security blob, but I'm not certain. > > >=20 > > > Mimi and Roberto, can we safely remove the inode locking in > > > process_measurement()? > >=20 > > I discussed a bit with Mimi. Her concern was the duplicate iint > > structure creation during concurrent file accesses. Now that inode > > integrity metadata have been moved to the inode security blob, we can > > take the iint->mutex out of the ima_iint_cache structure, and store it > > directly in the security blob. In this way, we can remove the inode > > lock. > >=20 > > Will write a patch and see if it passes our tests. >=20 > That's great, thanks Roberto. Assuming all goes well we'll want to > backport this everywhere we merged the remap_file_pages() patch. Welcome. Probably it can go down only until the kernel where IMA and EVM are LSMs. Roberto