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,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 90C7CC7112F for ; Mon, 21 Jan 2019 12:30:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5DC582084C for ; Mon, 21 Jan 2019 12:30:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728299AbfAUMak (ORCPT ); Mon, 21 Jan 2019 07:30:40 -0500 Received: from mga04.intel.com ([192.55.52.120]:25328 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728156AbfAUMak (ORCPT ); Mon, 21 Jan 2019 07:30:40 -0500 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 fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 21 Jan 2019 04:30:38 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,503,1539673200"; d="scan'208";a="127657221" Received: from vkunnari-mobl1.ger.corp.intel.com (HELO localhost) ([10.249.254.163]) by orsmga002.jf.intel.com with ESMTP; 21 Jan 2019 04:30:32 -0800 Date: Mon, 21 Jan 2019 14:30:31 +0200 From: Jarkko Sakkinen To: Roberto Sassu Cc: zohar@linux.ibm.com, david.safford@ge.com, monty.wiseman@ge.com, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, silviu.vlasceanu@huawei.com, Matthew Garrett Subject: Re: [PATCH v7 5/5] tpm: pass an array of tpm_extend_digest structures to tpm_pcr_extend() Message-ID: <20190121123031.GC9423@linux.intel.com> References: <20181213102945.30946-1-roberto.sassu@huawei.com> <20181213102945.30946-6-roberto.sassu@huawei.com> <20181220152122.GB10652@linux.intel.com> <20190118151253.GH4080@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.10.1 (2018-07-13) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On Mon, Jan 21, 2019 at 09:11:21AM +0100, Roberto Sassu wrote: > On 1/18/2019 4:12 PM, Jarkko Sakkinen wrote: > > On Thu, Jan 17, 2019 at 08:59:00AM +0100, Roberto Sassu wrote: > > > On 12/20/2018 4:21 PM, Jarkko Sakkinen wrote: > > > > On Thu, Dec 13, 2018 at 11:29:45AM +0100, Roberto Sassu wrote: > > > > > Currently, tpm_pcr_extend() accepts as an input only a SHA1 digest. > > > > > > > > > > This patch modifies the definition of tpm_pcr_extend() to allow other > > > > > kernel subsystems to pass a digest for each algorithm supported by the TPM. > > > > > All digests are processed by the TPM in one operation. > > > > > > > > > > If a tpm_pcr_extend() caller provides a subset of the supported algorithms, > > > > > the TPM driver extends the remaining PCR banks with the first digest > > > > > passed as an argument to the function. > > > > > > > > > > The new tpm_extend digest structure has been preferred to the tpm_digest > > > > > structure, to let the caller specify the size of the digest (which may be > > > > > unknown to the TPM driver). > > > > > > > > > > Due to the API change, ima_pcr_extend() and pcrlock() have been modified. > > > > > > > > > > Signed-off-by: Roberto Sassu > > > > > --- > > > > > drivers/char/tpm/tpm-interface.c | 24 +++++--------------- > > > > > drivers/char/tpm/tpm.h | 5 +++-- > > > > > drivers/char/tpm/tpm1-cmd.c | 13 ++++++++--- > > > > > drivers/char/tpm/tpm2-cmd.c | 35 +++++++++++++++++++++--------- > > > > > include/linux/tpm.h | 13 ++++++++--- > > > > > security/integrity/ima/ima_queue.c | 5 ++++- > > > > > security/keys/trusted.c | 5 ++++- > > > > > 7 files changed, 62 insertions(+), 38 deletions(-) > > > > > > > > > > diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c > > > > > index eb7c79ca8a94..911fea19e408 100644 > > > > > --- a/drivers/char/tpm/tpm-interface.c > > > > > +++ b/drivers/char/tpm/tpm-interface.c > > > > > @@ -478,42 +478,30 @@ EXPORT_SYMBOL_GPL(tpm_pcr_read); > > > > > * tpm_pcr_extend - extend a PCR value in SHA1 bank. > > > > > * @chip: a &struct tpm_chip instance, %NULL for the default chip > > > > > * @pcr_idx: the PCR to be retrieved > > > > > - * @hash: the hash value used to extend the PCR value > > > > > + * @count: number of tpm_extend_digest structures > > > > > + * @digests: array of tpm_extend_digest structures used to extend PCRs > > > > > * > > > > > * Note: with TPM 2.0 extends also those banks for which no digest was > > > > > * specified in order to prevent malicious use of those PCR banks. > > > > > * > > > > > * Return: same as with tpm_transmit_cmd() > > > > > */ > > > > > -int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash) > > > > > +int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count, > > > > > + const struct tpm_extend_digest *digests) > > > > > > > > Remove const. Document how @digests is used like the special meaning > > > > of the first index. I faintly remember asking this last time. > > > > > > > > > { > > > > > int rc; > > > > > - struct tpm_digest *digest_list; > > > > > - int i; > > > > > chip = tpm_find_get_ops(chip); > > > > > if (!chip) > > > > > return -ENODEV; > > > > > if (chip->flags & TPM_CHIP_FLAG_TPM2) { > > > > > - digest_list = kcalloc(chip->nr_allocated_banks, > > > > > - sizeof(*digest_list), GFP_KERNEL); > > > > > - if (!digest_list) > > > > > - return -ENOMEM; > > > > > - > > > > > - for (i = 0; i < chip->nr_allocated_banks; i++) { > > > > > - digest_list[i].alg_id = chip->allocated_banks[i].alg_id; > > > > > - memcpy(digest_list[i].digest, hash, TPM_DIGEST_SIZE); > > > > > - } > > > > > - > > > > > - rc = tpm2_pcr_extend(chip, pcr_idx, chip->nr_allocated_banks, > > > > > - digest_list); > > > > > - kfree(digest_list); > > > > > + rc = tpm2_pcr_extend(chip, pcr_idx, count, digests); > > > > > tpm_put_ops(chip); > > > > > return rc; > > > > > } > > > > > - rc = tpm1_pcr_extend(chip, pcr_idx, hash, > > > > > + rc = tpm1_pcr_extend(chip, pcr_idx, count, digests, > > > > > "attempting extend a PCR value"); > > > > > > > > The validation is missing that the provided array has only one element > > > > and the algorithm is SHA1. Could be done also inside tpm1_pcr_extend() > > > > but what you are doing to that function does not make any sense so > > > > better to do it here. > > > > > > > > > tpm_put_ops(chip); > > > > > return rc; > > > > > diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h > > > > > index 64d93d26087f..6b446504d2fe 100644 > > > > > --- a/drivers/char/tpm/tpm.h > > > > > +++ b/drivers/char/tpm/tpm.h > > > > > @@ -504,7 +504,8 @@ int tpm1_auto_startup(struct tpm_chip *chip); > > > > > int tpm1_do_selftest(struct tpm_chip *chip); > > > > > int tpm1_get_timeouts(struct tpm_chip *chip); > > > > > unsigned long tpm1_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal); > > > > > -int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash, > > > > > +int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count, > > > > > + const struct tpm_extend_digest *digests, > > > > > const char *log_msg); > > > > > int tpm1_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf); > > > > > ssize_t tpm1_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap, > > > > > @@ -551,7 +552,7 @@ int tpm2_get_timeouts(struct tpm_chip *chip); > > > > > int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx, > > > > > struct tpm_digest *digest, u16 *digest_size_ptr); > > > > > int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count, > > > > > - struct tpm_digest *digests); > > > > > + const struct tpm_extend_digest *digests); > > > > > int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max); > > > > > void tpm2_flush_context_cmd(struct tpm_chip *chip, u32 handle, > > > > > unsigned int flags); > > > > > diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c > > > > > index 8b70a7f884a7..04ee10284b8c 100644 > > > > > --- a/drivers/char/tpm/tpm1-cmd.c > > > > > +++ b/drivers/char/tpm/tpm1-cmd.c > > > > > @@ -449,12 +449,20 @@ int tpm1_get_timeouts(struct tpm_chip *chip) > > > > > } > > > > > #define TPM_ORD_PCR_EXTEND 20 > > > > > -int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash, > > > > > +int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count, > > > > > + const struct tpm_extend_digest *digests, > > > > > const char *log_msg) > > > > > { > > > > > struct tpm_buf buf; > > > > > + u8 dummy_hash[TPM_DIGEST_SIZE] = { 0 }; > > > > > + const u8 *hash; > > > > > int rc; > > > > > + hash = dummy_hash; > > > > > + if (count) > > > > > + memcpy(dummy_hash, digests[0].data, > > > > > + min(digests[0].size, (u16)sizeof(dummy_hash))); > > > > > + > > > > > > > > You copy memory from one place to another without any good reason to do > > > > so. My suggestion is just not to change tpm1_pcr_extend() at all. > > > > > > > > > rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCR_EXTEND); > > > > > if (rc) > > > > > return rc; > > > > > @@ -743,7 +751,6 @@ int tpm1_auto_startup(struct tpm_chip *chip) > > > > > */ > > > > > int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr) > > > > > { > > > > > - u8 dummy_hash[TPM_DIGEST_SIZE] = { 0 }; > > > > > struct tpm_buf buf; > > > > > unsigned int try; > > > > > int rc; > > > > > @@ -751,7 +758,7 @@ int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr) > > > > > /* for buggy tpm, flush pcrs with extend to selected dummy */ > > > > > if (tpm_suspend_pcr) > > > > > - rc = tpm1_pcr_extend(chip, tpm_suspend_pcr, dummy_hash, > > > > > + rc = tpm1_pcr_extend(chip, tpm_suspend_pcr, 0, NULL, > > > > > "extending dummy pcr before suspend"); > > > > > rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_SAVESTATE); > > > > > diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c > > > > > index 6ce5173cf0e5..77b5808270c6 100644 > > > > > --- a/drivers/char/tpm/tpm2-cmd.c > > > > > +++ b/drivers/char/tpm/tpm2-cmd.c > > > > > @@ -247,21 +247,22 @@ struct tpm2_null_auth_area { > > > > > * > > > > > * @chip: TPM chip to use. > > > > > * @pcr_idx: index of the PCR. > > > > > - * @count: number of digests passed. > > > > > - * @digests: list of pcr banks and corresponding digest values to extend. > > > > > + * @count: number of tpm_extend_digest passed. > > > > > + * @digests: array of tpm_extend_digest with digest values to extend. > > > > > * > > > > > * Return: Same as with tpm_transmit_cmd. > > > > > */ > > > > > > > > The documentation about @digests. > > > > > > > > > int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count, > > > > > - struct tpm_digest *digests) > > > > > + const struct tpm_extend_digest *digests) > > > > > { > > > > > struct tpm_buf buf; > > > > > struct tpm2_null_auth_area auth_area; > > > > > + const struct tpm_extend_digest *digest; > > > > > + u8 dummy_hash[SHA512_DIGEST_SIZE] = { 0 }; > > > > > + const u8 *hash; > > > > > int rc; > > > > > int i; > > > > > - > > > > > - if (count > chip->nr_allocated_banks) > > > > > - return -EINVAL; > > > > > + int j; > > > > > rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND); > > > > > if (rc) > > > > > @@ -277,11 +278,25 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count, > > > > > tpm_buf_append_u32(&buf, sizeof(struct tpm2_null_auth_area)); > > > > > tpm_buf_append(&buf, (const unsigned char *)&auth_area, > > > > > sizeof(auth_area)); > > > > > - tpm_buf_append_u32(&buf, count); > > > > > + tpm_buf_append_u32(&buf, chip->nr_allocated_banks); > > > > > + > > > > > + if (count) > > > > > + memcpy(dummy_hash, digests[0].data, digests[0].size); > > > > > + > > > > > + for (i = 0; i < chip->nr_allocated_banks; i++) { > > > > > + tpm_buf_append_u16(&buf, chip->allocated_banks[i].alg_id); > > > > > + > > > > > + hash = dummy_hash; > > > > > + for (j = 0; j < count; j++) { > > > > > + digest = digests + j; > > > > > + > > > > > + if (digest->alg_id == chip->allocated_banks[i].alg_id) { > > > > > + hash = digest->data; > > > > > + break; > > > > > > > > I think the whole design is just wrong. I did re-read your response to > > > > v6 again and I'm very sorry, but I just don't get this. Caller has all > > > > the information (from struct tpm_chip) to give the correct data. This > > > > function should validate that data (check algorithm ID and that's it). > > > > > > The question is if checking tpm->allocated_banks is a strict > > > requirement, or we can allow callers to use the algorithm they are > > > currently using, without further modifications. > > > > If you want to know what is available, you can use that array. > > > > > > Extending with the dummy hash should be done by the caller when > > > > preparing the array, not baked into this function. This kind of also > > > > makes obvious that we don't need this new struct. There should never be > > > > a local variable (whose size is BTW randomly chosen) called dummy_hash. > > > > > > This means duplicating the code for each caller. Currently, this work is > > > done by the TPM driver. > > > > It is better than fix the usage pattern like this. Not only that, but > > this somewhat complicated behavior now completely undocumented in the > > function description. > > > > You are making strong assumptions how some other subsystem might use > > extend operation. I will rather accept redundancy and consider > > consolidation later when there are two clients. Rather keep the TPM > > provided function simple and stupid. > > Ok, if I understood it correctly, every caller of tpm_pcr_extend() will pass > an array of tpm_digest structures. > > I will not introduce a new structure, as the caller has to use > algorithms from chip->allocated_banks and passing the digest size is not > necessary. > > tpm_pcr_extend() will reject incomplete arrays (one or more algorithms > are missing). To simplify even more tpm_pcr_extend(), I assume and check > that passed algorithms are in the same order as those in > chip->allocated_banks. > > I will remove the 'count' parameter from tpm_pcr_extend(), as the number > of tpm_digest structures will be always chip->nr_allocated_banks. Sounds like a plan. I think some redundancy is almost always better than hard to undestand API. /Jarkko