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From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Roberto Sassu <roberto.sassu@huawei.com>
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
Subject: Re: [PATCH v5 7/7] tpm: pass an array of tpm_bank_list structures to tpm_pcr_extend()
Date: Fri, 16 Nov 2018 17:03:52 +0200	[thread overview]
Message-ID: <20181116150352.GA3612@linux.intel.com> (raw)
In-Reply-To: <20181114153108.12907-8-roberto.sassu@huawei.com>

On Wed, Nov 14, 2018 at 04:31:08PM +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.

What is the legit use case for this?

> The new tpm_bank_list 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 <roberto.sassu@huawei.com>

Should be dropped from the patch set as it is not taken advatange of
but I can still try to give some feedback.

> ---
>  drivers/char/tpm/tpm-interface.c   | 24 +++++---------------
>  drivers/char/tpm/tpm.h             |  6 ++---
>  drivers/char/tpm/tpm1-cmd.c        | 14 ++++++++----
>  drivers/char/tpm/tpm2-cmd.c        | 36 +++++++++++++++++++++---------
>  include/linux/tpm.h                | 13 ++++++++---
>  security/integrity/ima/ima_queue.c |  5 ++++-
>  security/keys/trusted.c            |  5 ++++-
>  7 files changed, 63 insertions(+), 40 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index f0e1456440d7..5495223d3f7b 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_bank_list structures
> + * @bank_list:	array of tpm_bank_list structures used to extend the PCR value
>   *
>   * 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_bank_list *bank_list)
>  {
>  	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, bank_list);
>  		tpm_put_ops(chip);
>  		return rc;
>  	}
>  
> -	rc = tpm1_pcr_extend(chip, pcr_idx, hash,
> +	rc = tpm1_pcr_extend(chip, pcr_idx, count, bank_list,
>  			     "attempting extend a PCR value");
>  	tpm_put_ops(chip);
>  	return rc;
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index 023ddf42038b..4296c720ebb4 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -504,8 +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,
> -		    const char *log_msg);
> +int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
> +		    const struct tpm_bank_list *bank_list, 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,
>  		    const char *desc, size_t min_cap_length);
> @@ -551,7 +551,7 @@ int tpm2_get_timeouts(struct tpm_chip *chip);
>  int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
>  		  struct tpm_digest *digest_struct, u16 *digest_size_ptr);
>  int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
> -		    struct tpm_digest *digests);
> +		    const struct tpm_bank_list *bank_list);
>  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..439ac749517c 100644
> --- a/drivers/char/tpm/tpm1-cmd.c
> +++ b/drivers/char/tpm/tpm1-cmd.c
> @@ -449,12 +449,19 @@ 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,
> -		    const char *log_msg)
> +int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
> +		    const struct tpm_bank_list *bank_list, 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, bank_list[0].extend_array,
> +		       min(bank_list[0].digest_size, (u16)sizeof(dummy_hash)));
> +
>  	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCR_EXTEND);

This is probably mistake? I mean dummy_hash is not used.

>  	if (rc)
>  		return rc;
> @@ -743,7 +750,6 @@ 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 +757,7 @@ 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 974465f04b78..40eb1a044451 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -248,21 +248,22 @@ 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_bank_list passed.
> + * @bank_list:	array of tpm_bank_list with digest values to extend.
>   *
>   * Return: Same as with tpm_transmit_cmd.
>   */
>  int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
> -		    struct tpm_digest *digests)
> +		    const struct tpm_bank_list *bank_list)
>  {
>  	struct tpm_buf buf;
>  	struct tpm2_null_auth_area auth_area;
> +	const struct tpm_bank_list *item;
> +	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)
> @@ -278,11 +279,26 @@ 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, bank_list[0].extend_array,
> +		       bank_list[0].digest_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++) {
> +			item = bank_list + j;
> +
> +			if (item->alg_id == chip->allocated_banks[i].alg_id) {
> +				hash = item->extend_array;
> +				break;
> +			}
> +		}
>  
> -	for (i = 0; i < count; i++) {
> -		tpm_buf_append_u16(&buf, digests[i].alg_id);
> -		tpm_buf_append(&buf, (const unsigned char *)&digests[i].digest,
> +		tpm_buf_append(&buf, hash,
>  			       chip->allocated_banks[i].digest_size);
>  	}
>  
> diff --git a/include/linux/tpm.h b/include/linux/tpm.h
> index fcdd33ae9969..16e5ff1f0294 100644
> --- a/include/linux/tpm.h
> +++ b/include/linux/tpm.h
> @@ -52,6 +52,12 @@ struct tpm_bank_info {
>  	u16 crypto_id;
>  };
>  
> +struct tpm_bank_list {
> +	u8 alg_id;
> +	u16 digest_size;
> +	const u8 *extend_array;
> +};

You should document this structure.

> +
>  enum TPM_OPS_FLAGS {
>  	TPM_OPS_AUTO_STARTUP = BIT(0),
>  };
> @@ -79,7 +85,8 @@ struct tpm_class_ops {
>  extern int tpm_is_tpm2(struct tpm_chip *chip);
>  extern int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
>  			struct tpm_digest *digest_struct);
> -extern int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash);
> +extern int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
> +			  const struct tpm_bank_list *bank_list);
>  extern int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen);
>  extern int tpm_get_random(struct tpm_chip *chip, u8 *data, size_t max);
>  extern int tpm_seal_trusted(struct tpm_chip *chip,
> @@ -101,8 +108,8 @@ static inline int tpm_pcr_read(struct tpm_chip *chip, int pcr_idx,
>  	return -ENODEV;
>  }
>  
> -static inline int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
> -				 const u8 *hash)
> +static inline int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
> +				 const struct tpm_bank_list *bank_list)
>  {
>  	return -ENODEV;
>  }
> diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
> index b186819bd5aa..24024edef316 100644
> --- a/security/integrity/ima/ima_queue.c
> +++ b/security/integrity/ima/ima_queue.c
> @@ -140,12 +140,15 @@ unsigned long ima_get_binary_runtime_size(void)
>  
>  static int ima_pcr_extend(const u8 *hash, int pcr)
>  {
> +	struct tpm_bank_list bank_item = { .alg_id = TPM_ALG_SHA1,
> +					   .digest_size = TPM_DIGEST_SIZE,
> +					   .extend_array = hash };

Item is a list?

>  	int result = 0;
>  
>  	if (!ima_tpm_chip)
>  		return result;
>  
> -	result = tpm_pcr_extend(ima_tpm_chip, pcr, hash);
> +	result = tpm_pcr_extend(ima_tpm_chip, pcr, 1, &bank_item);
>  	if (result != 0)
>  		pr_err("Error Communicating to TPM chip, result: %d\n", result);
>  	return result;
> diff --git a/security/keys/trusted.c b/security/keys/trusted.c
> index ff6789365a12..d2a3129a95f9 100644
> --- a/security/keys/trusted.c
> +++ b/security/keys/trusted.c
> @@ -380,6 +380,9 @@ EXPORT_SYMBOL_GPL(trusted_tpm_send);
>  static int pcrlock(const int pcrnum)
>  {
>  	unsigned char hash[SHA1_DIGEST_SIZE];
> +	struct tpm_bank_list bank_item = { .alg_id = TPM_ALG_SHA1,
> +					   .digest_size = sizeof(hash),
> +					   .extend_array = hash }
>  	int ret;
>  
>  	if (!capable(CAP_SYS_ADMIN))
> @@ -387,7 +390,7 @@ static int pcrlock(const int pcrnum)
>  	ret = tpm_get_random(NULL, hash, SHA1_DIGEST_SIZE);
>  	if (ret != SHA1_DIGEST_SIZE)
>  		return ret;
> -	return tpm_pcr_extend(NULL, pcrnum, hash) ? -EINVAL : 0;
> +	return tpm_pcr_extend(NULL, pcrnum, 1, &bank_item) ? -EINVAL : 0;
>  }
>  
>  /*
> -- 
> 2.17.1
> 

/Jarkko

  reply	other threads:[~2018-11-16 15:03 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-14 15:31 [PATCH v5 0/7] tpm: retrieve digest size of unknown algorithms from TPM Roberto Sassu
2018-11-14 15:31 ` [PATCH v5 1/7] tpm: dynamically allocate the allocated_banks array Roberto Sassu
2018-11-16 13:36   ` Jarkko Sakkinen
2018-11-14 15:31 ` [PATCH v5 2/7] tpm: remove definition of TPM2_ACTIVE_PCR_BANKS Roberto Sassu
2018-11-16 13:38   ` Jarkko Sakkinen
2018-11-28  7:50     ` Roberto Sassu
2018-11-28 12:17     ` Roberto Sassu
2018-11-29 12:04       ` Roberto Sassu
2018-11-30 19:41         ` Jarkko Sakkinen
2018-11-30 19:45           ` Jarkko Sakkinen
2018-11-30 22:18             ` Jarkko Sakkinen
2018-12-03  9:59             ` Roberto Sassu
2018-12-03 17:31               ` Jarkko Sakkinen
2018-11-14 15:31 ` [PATCH v5 3/7] tpm: rename and export tpm2_digest and tpm2_algorithms Roberto Sassu
2018-11-14 15:31 ` [PATCH v5 4/7] tpm: modify tpm_pcr_read() definition to pass a TPM hash algorithm Roberto Sassu
2018-11-16 13:41   ` Jarkko Sakkinen
2018-11-14 15:31 ` [PATCH v5 5/7] tpm: retrieve digest size of unknown algorithms with PCR read Roberto Sassu
2018-11-14 15:31 ` [PATCH v5 6/7] tpm: ensure that the output of PCR read contains the correct digest size Roberto Sassu
2018-11-16 13:41   ` Jarkko Sakkinen
2018-11-16 16:06     ` Roberto Sassu
2018-11-18  7:32       ` Jarkko Sakkinen
2018-11-19  8:14         ` Roberto Sassu
2018-11-19 14:33           ` Jarkko Sakkinen
2018-11-19 15:09             ` Roberto Sassu
2018-11-19 16:07               ` Jarkko Sakkinen
2018-11-28  8:40                 ` Roberto Sassu
2018-11-28 19:19                   ` Jarkko Sakkinen
2018-11-14 15:31 ` [PATCH v5 7/7] tpm: pass an array of tpm_bank_list structures to tpm_pcr_extend() Roberto Sassu
2018-11-16 15:03   ` Jarkko Sakkinen [this message]
2018-11-16 15:55     ` Roberto Sassu
2018-11-18  7:27       ` Jarkko Sakkinen
2018-11-19  4:57         ` Mimi Zohar
2018-11-19  8:16           ` Roberto Sassu
2018-11-19 14:33             ` Mimi Zohar
2018-11-19 14:39             ` Jarkko Sakkinen
2018-11-18  7:29       ` Jarkko Sakkinen
2018-11-19  8:22         ` Roberto Sassu
2018-11-19 14:42           ` Jarkko Sakkinen

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