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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=unavailable 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 DC065C43381 for ; Mon, 1 Apr 2019 23:46:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B573E20828 for ; Mon, 1 Apr 2019 23:46:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726895AbfDAXqd (ORCPT ); Mon, 1 Apr 2019 19:46:33 -0400 Received: from mga14.intel.com ([192.55.52.115]:27624 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725893AbfDAXqd (ORCPT ); Mon, 1 Apr 2019 19:46:33 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 01 Apr 2019 16:46:32 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,298,1549958400"; d="scan'208";a="147173511" Received: from unknown (HELO localhost) ([10.249.254.142]) by orsmga002.jf.intel.com with ESMTP; 01 Apr 2019 16:46:27 -0700 Date: Tue, 2 Apr 2019 02:46:25 +0300 From: Jarkko Sakkinen To: Kees Cook Cc: Jason Gunthorpe , James Bottomley , Phil Baker , Craig Robson , Laura Abbott , Tomas Winkler , linux-kernel@vger.kernel.org, Peter Huewe , Arnd Bergmann , linux-integrity@vger.kernel.org Subject: Re: [PATCH v3] tpm: Actually fail on TPM errors during "get random" Message-ID: <20190401234625.GA29016@linux.intel.com> References: <20190401190607.GA23795@beast> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190401190607.GA23795@beast> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 01, 2019 at 12:06:07PM -0700, Kees Cook wrote: > A "get random" may fail with a TPM error, but those codes were returned > as-is to the caller, which assumed the result was the number of bytes > that had been written to the target buffer, which could lead to a kernel > heap memory exposure and over-read. > > This fixes tpm1_get_random() to mask positive TPM errors into -EIO, as > before. > > [ 18.092103] tpm tpm0: A TPM error (379) occurred attempting get random > [ 18.092106] usercopy: Kernel memory exposure attempt detected from SLUB object 'kmalloc-64' (offset 0, size 379)! > > Link: https://bugzilla.redhat.com/show_bug.cgi?id=1650989 > Reported-by: Phil Baker > Reported-by: Craig Robson > Fixes: 7aee9c52d7ac ("tpm: tpm1: rewrite tpm1_get_random() using tpm_buf structure") > Cc: Laura Abbott > Cc: Tomas Winkler > Cc: Jarkko Sakkinen > Cc: stable@vger.kernel.org > Signed-off-by: Kees Cook > --- > v3: fix never-succeed, limit checks to tpm cmd return (James, Jason) > v2: also fix tpm2 implementation (Jason Gunthorpe) > --- > drivers/char/tpm/tpm1-cmd.c | 7 +++++-- > drivers/char/tpm/tpm2-cmd.c | 7 +++++-- > 2 files changed, 10 insertions(+), 4 deletions(-) > > diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c > index 85dcf2654d11..faacbe1ffa1a 100644 > --- a/drivers/char/tpm/tpm1-cmd.c > +++ b/drivers/char/tpm/tpm1-cmd.c > @@ -510,7 +510,7 @@ struct tpm1_get_random_out { > * > * Return: > * * number of bytes read > - * * -errno or a TPM return code otherwise > + * * -errno (positive TPM return codes are masked to -EIO) > */ > int tpm1_get_random(struct tpm_chip *chip, u8 *dest, size_t max) > { > @@ -531,8 +531,11 @@ int tpm1_get_random(struct tpm_chip *chip, u8 *dest, size_t max) > > rc = tpm_transmit_cmd(chip, &buf, sizeof(out->rng_data_len), > "attempting get random"); > - if (rc) > + if (rc) { > + if (rc > 0) > + rc = -EIO; > goto out; > + } > > out = (struct tpm1_get_random_out *)&buf.data[TPM_HEADER_SIZE]; > > diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c > index e74c5b7b64bf..8ffa6af61580 100644 > --- a/drivers/char/tpm/tpm2-cmd.c > +++ b/drivers/char/tpm/tpm2-cmd.c > @@ -301,7 +301,7 @@ struct tpm2_get_random_out { > * > * Return: > * size of the buffer on success, > - * -errno otherwise > + * -errno otherwise ((positive TPM return codes are masked to -EIO) > */ > int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max) > { > @@ -328,8 +328,11 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max) > offsetof(struct tpm2_get_random_out, > buffer), > "attempting get random"); > - if (err) > + if (err) { > + if (err > 0) > + err = -EIO; > goto out; > + } > > out = (struct tpm2_get_random_out *) > &buf.data[TPM_HEADER_SIZE]; > -- > 2.17.1 > > > -- > Kees Cook Reviewed-by: Jarkko Sakkinen /Jarkko