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 X-Spam-Level: X-Spam-Status: No, score=-23.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BFAA6C2B9F4 for ; Mon, 14 Jun 2021 19:06:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 93CF661042 for ; Mon, 14 Jun 2021 19:06:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232975AbhFNTIx (ORCPT ); Mon, 14 Jun 2021 15:08:53 -0400 Received: from linux.microsoft.com ([13.77.154.182]:58830 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232802AbhFNTIw (ORCPT ); Mon, 14 Jun 2021 15:08:52 -0400 Received: from sequoia (162-237-133-238.lightspeed.rcsntx.sbcglobal.net [162.237.133.238]) by linux.microsoft.com (Postfix) with ESMTPSA id 1E5AB20B83C2; Mon, 14 Jun 2021 12:06:48 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 1E5AB20B83C2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1623697609; bh=GyTTjrY1m6FZD8r7ati75j2Y/QHH6dR94ffl12D95/A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=gzMlK8A9qDasP6aFEbh9BZrnV6PYy21iOtrYeg3xfSc+qo8Mhb8QRxbdMrSPSCzB6 zlxnVn/y5MSAwrArDpeXykmGwhfIPAsp9NnL+HSqH1s9QKzb7zBN5OQBoIKJn1Z81q 6L55T6eBH9yA4IgnuCwDMvnqAVvcVxXeXcb6lkqw= Date: Mon, 14 Jun 2021 14:06:46 -0500 From: Tyler Hicks To: Jens Wiklander Cc: Allen Pais , Sumit Garg , Peter Huewe , Jarkko Sakkinen , Jason Gunthorpe , Vikas Gupta , Thirupathaiah Annapureddy , Pavel Tatashin , =?utf-8?B?UmFmYcWCIE1pxYJlY2tp?= , op-tee@lists.trustedfirmware.org, linux-integrity@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com, linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 4/8] optee: Clear stale cache entries during initialization Message-ID: <20210614190646.GW4910@sequoia> References: <20210610210913.536081-1-tyhicks@linux.microsoft.com> <20210610210913.536081-5-tyhicks@linux.microsoft.com> <20210614082715.GC1033436@jade> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210614082715.GC1033436@jade> Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On 2021-06-14 10:27:15, Jens Wiklander wrote: > On Thu, Jun 10, 2021 at 04:09:09PM -0500, Tyler Hicks wrote: > > The shm cache could contain invalid addresses if > > optee_disable_shm_cache() was not called from the .shutdown hook of the > > previous kernel before a kexec. These addresses could be unmapped or > > they could point to mapped but unintended locations in memory. > > > > Clear the shared memory cache, while being careful to not translate the > > addresses returned from OPTEE_SMC_DISABLE_SHM_CACHE, during driver > > initialization. Once all pre-cache shm objects are removed, proceed with > > enabling the cache so that we know that we can handle cached shm objects > > with confidence later in the .shutdown hook. > > > > Signed-off-by: Tyler Hicks > > --- > > drivers/tee/optee/call.c | 11 ++++++++++- > > drivers/tee/optee/core.c | 13 +++++++++++-- > > drivers/tee/optee/optee_private.h | 2 +- > > 3 files changed, 22 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/tee/optee/call.c b/drivers/tee/optee/call.c > > index 6e6eb836e9b6..5dcba6105ed7 100644 > > --- a/drivers/tee/optee/call.c > > +++ b/drivers/tee/optee/call.c > > @@ -419,8 +419,10 @@ void optee_enable_shm_cache(struct optee *optee) > > * optee_disable_shm_cache() - Disables caching of some shared memory allocation > > * in OP-TEE > > * @optee: main service struct > > + * @is_mapped: true if the cached shared memory addresses were mapped by this > > + * kernel, are safe to dereference, and should be freed > > */ > > -void optee_disable_shm_cache(struct optee *optee) > > +void optee_disable_shm_cache(struct optee *optee, bool is_mapped) > > { > > struct optee_call_waiter w; > > > > @@ -439,6 +441,13 @@ void optee_disable_shm_cache(struct optee *optee) > > if (res.result.status == OPTEE_SMC_RETURN_OK) { > > struct tee_shm *shm; > > > > + /* > > + * Shared memory references that were not mapped by > > + * this kernel must be ignored to prevent a crash. > > + */ > > + if (!is_mapped) > > + continue; > > + > > shm = reg_pair_to_ptr(res.result.shm_upper32, > > res.result.shm_lower32); > > tee_shm_free(shm); > > diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c > > index 0987074d7ed0..6974e1104bd4 100644 > > --- a/drivers/tee/optee/core.c > > +++ b/drivers/tee/optee/core.c > > @@ -589,7 +589,7 @@ static int optee_remove(struct platform_device *pdev) > > * reference counters and also avoid wild pointers in secure world > > * into the old shared memory range. > > */ > > - optee_disable_shm_cache(optee); > > + optee_disable_shm_cache(optee, true); > > Naked "true" or "false" parameters are normally not very descriptive. > Would it make sense to write this as: > optee_disable_shm_cache(optee, true /*is_mapped*/); > instead (same for the other call sites in this patch)? That way it would > be easier to see what it is that is true or false. Yeah, I understand the issue with the naked bools. What about turning 'optee_disable_shm_cache(struct optee *optee, bool is_mapped)' into '__optee_disable_shm_cache(struct optee *optee, bool is_mapped)' and introducing these two wrappers: /** * optee_disable_shm_cache() - Disables caching of mapped shared memory * allocations in OP-TEE * @optee: main service struct */ void optee_disable_shm_cache(struct optee *optee) { return __optee_disable_shm_cache(optee, true); } /** * optee_disable_unmapped_shm_cache() - Disables caching of shared memory * allocations in OP-TEE which are not * currently mapped * @optee: main service struct */ void optee_disable_unmapped_shm_cache(struct optee *optee) { return __optee_disable_shm_cache(optee, false); } Existing callers of optee_disable_shm_cache() remain unchanged and we just add one caller of optee_disable_unmapped_shm_cache() with this patch. Tyler > > /Jens > > > > > /* > > * The two devices have to be unregistered before we can free the > > @@ -619,7 +619,7 @@ static int optee_remove(struct platform_device *pdev) > > */ > > static void optee_shutdown(struct platform_device *pdev) > > { > > - optee_disable_shm_cache(platform_get_drvdata(pdev)); > > + optee_disable_shm_cache(platform_get_drvdata(pdev), true); > > } > > > > static int optee_probe(struct platform_device *pdev) > > @@ -716,6 +716,15 @@ static int optee_probe(struct platform_device *pdev) > > optee->memremaped_shm = memremaped_shm; > > optee->pool = pool; > > > > + /* > > + * Ensure that there are no pre-existing shm objects before enabling > > + * the shm cache so that there's no chance of receiving an invalid > > + * address during shutdown. This could occur, for example, if we're > > + * kexec booting from an older kernel that did not properly cleanup the > > + * shm cache. > > + */ > > + optee_disable_shm_cache(optee, false); > > + > > optee_enable_shm_cache(optee); > > > > if (optee->sec_caps & OPTEE_SMC_SEC_CAP_DYNAMIC_SHM) > > diff --git a/drivers/tee/optee/optee_private.h b/drivers/tee/optee/optee_private.h > > index e25b216a14ef..16d8c82213e7 100644 > > --- a/drivers/tee/optee/optee_private.h > > +++ b/drivers/tee/optee/optee_private.h > > @@ -158,7 +158,7 @@ int optee_invoke_func(struct tee_context *ctx, struct tee_ioctl_invoke_arg *arg, > > int optee_cancel_req(struct tee_context *ctx, u32 cancel_id, u32 session); > > > > void optee_enable_shm_cache(struct optee *optee); > > -void optee_disable_shm_cache(struct optee *optee); > > +void optee_disable_shm_cache(struct optee *optee, bool is_mapped); > > > > int optee_shm_register(struct tee_context *ctx, struct tee_shm *shm, > > struct page **pages, size_t num_pages, > > -- > > 2.25.1 > > >