Re: [PATCH 2/2] tpm: enhance TPM 2.0 PCR extend to support multiple banks

[Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On Sat, Oct 08, 2016 at 10:15:57PM -0400, Nayna Jain wrote:
> Like TPM 1.2, the current device driver for TPM 2.0 supports
> extending only to the SHA1 PCR bank. But the TPM 2.0 supports multiple
> PCR banks and the specification recommends extending to all active PCR
> banks, this patch enhances the existing device driver support for
> TPM 2.0 extend function and its in-kernel interface to extend to all
> active PCR banks.
> 
> The existing in-kernel interface expects only a SHA1 digest.
> Hence, to extend all active PCR banks with differing digest sizes
> for TPM 2.0, the SHA1 digest is padded with trailing 0's as needed.
> 
> Signed-off-by: Nayna Jain <nayna-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>

Please use struct tpm_buf for variable size stuff. You can see example
from trusted keys code in tpm2-cmd.c how to work on it.

/Jarkko

> ---
>  drivers/char/tpm/tpm-interface.c | 17 ++++++++--
>  drivers/char/tpm/tpm2-cmd.c      | 71 ++++++++++++++++++++++++++--------------
>  drivers/char/tpm/tpm2.h          | 18 ++++++++++
>  3 files changed, 79 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 7743e8a..5dd5005 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -7,6 +7,7 @@
>   * Dave Safford <safford-aZOuKsOsJu3MbYB6QlFGEg@public.gmane.org>
>   * Reiner Sailer <sailer-aZOuKsOsJu3MbYB6QlFGEg@public.gmane.org>
>   * Kylene Hall <kjhall-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
> + * Nayna Jain <nayna-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
>   *
>   * Maintained by: <tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>
>   *
> @@ -32,6 +33,7 @@
>  #include <linux/pm_runtime.h>
>  
>  #include "tpm.h"
> +#include "tpm2.h"
>  #include "tpm_eventlog.h"
>  
>  #define TPM_MAX_ORDINAL 243
> @@ -752,7 +754,7 @@ static const struct tpm_input_header pcrextend_header = {
>  int tpm_pcr_extend(u32 chip_num, int pcr_idx, const u8 *hash)
>  {
>  	struct tpm_cmd_t cmd;
> -	int rc;
> +	int i, rc;
>  	struct tpm_chip *chip;
>  
>  	chip = tpm_chip_find_get(chip_num);
> @@ -760,7 +762,18 @@ int tpm_pcr_extend(u32 chip_num, int pcr_idx, const u8 *hash)
>  		return -ENODEV;
>  
>  	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
> -		rc = tpm2_pcr_extend(chip, pcr_idx, hash);
> +		struct tpml_digest_values d_values;
> +
> +		memset(&d_values, 0, sizeof(d_values));
> +
> +		for (i = 0; i < chip->no_of_active_banks; i++) {
> +			d_values.digests[i].alg_id =
> +				chip->active_banks[i];
> +			memcpy(d_values.digests[i].digest, hash,
> +			       TPM_DIGEST_SIZE);
> +			d_values.count++;
> +		}
> +		rc = tpm2_pcr_extend(chip, pcr_idx, &d_values);
>  		tpm_put_ops(chip);
>  		return rc;
>  	}
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index c597cf3c..8ba2992 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -16,6 +16,7 @@
>   */
>  
>  #include "tpm.h"
> +#include "tpm2.h"
>  #include <crypto/hash_info.h>
>  #include <keys/trusted-type.h>
>  
> @@ -53,22 +54,6 @@ struct tpm2_pcr_read_out {
>  	u8	digest[TPM_DIGEST_SIZE];
>  } __packed;
>  
> -struct tpm2_null_auth_area {
> -	__be32			handle;
> -	__be16			nonce_size;
> -	u8			attributes;
> -	__be16			auth_size;
> -} __packed;
> -
> -struct tpm2_pcr_extend_in {
> -	__be32				pcr_idx;
> -	__be32				auth_area_size;
> -	struct tpm2_null_auth_area	auth_area;
> -	__be32				digest_cnt;
> -	__be16				hash_alg;
> -	u8				digest[TPM_DIGEST_SIZE];
> -} __packed;
> -
>  struct tpm2_get_tpm_pt_in {
>  	__be32	cap_id;
>  	__be32	property_id;
> @@ -300,38 +285,74 @@ int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
>  
>  static const struct tpm_input_header tpm2_pcrextend_header = {
>  	.tag = cpu_to_be16(TPM2_ST_SESSIONS),
> -	.length = cpu_to_be32(TPM2_GET_PCREXTEND_IN_SIZE),
>  	.ordinal = cpu_to_be32(TPM2_CC_PCR_EXTEND)
>  };
>  
>  /**
>   * tpm2_pcr_extend() - extend a PCR value
> - * @chip:	TPM chip to use.
> - * @pcr_idx:	index of the PCR.
> - * @hash:	hash value to use for the extend operation.
> + * @chip:		TPM chip to use.
> + * @pcr_idx:		index of the PCR.
> + * @digest_values:	list of hash values to be extended.
>   *
>   * 0 is returned when the operation is successful. If a negative number is
>   * returned it remarks a POSIX error code. If a positive number is returned
>   * it remarks a TPM error.
>   */
> -int tpm2_pcr_extend(struct tpm_chip *chip, int pcr_idx, const u8 *hash)
> +int tpm2_pcr_extend(struct tpm_chip *chip, int pcr_idx,
> +		    struct tpml_digest_values *digest_list)
>  {
>  	struct tpm2_cmd cmd;
> -	int rc;
> +	int i, j, rc;
> +	void *marker;
> +	size_t size;
> +	u32 halg_size;
> +	u16 halg;
>  
>  	cmd.header.in = tpm2_pcrextend_header;
> +	size = sizeof(struct tpm_input_header);
> +
>  	cmd.params.pcrextend_in.pcr_idx = cpu_to_be32(pcr_idx);
> +	size = size + sizeof(cmd.params.pcrextend_in.pcr_idx);
> +
>  	cmd.params.pcrextend_in.auth_area_size =
>  		cpu_to_be32(sizeof(struct tpm2_null_auth_area));
> +	size = size + sizeof(cmd.params.pcrextend_in.auth_area_size);
> +
>  	cmd.params.pcrextend_in.auth_area.handle =
>  		cpu_to_be32(TPM2_RS_PW);
>  	cmd.params.pcrextend_in.auth_area.nonce_size = 0;
>  	cmd.params.pcrextend_in.auth_area.attributes = 0;
>  	cmd.params.pcrextend_in.auth_area.auth_size = 0;
> -	cmd.params.pcrextend_in.digest_cnt = cpu_to_be32(1);
> -	cmd.params.pcrextend_in.hash_alg = cpu_to_be16(TPM2_ALG_SHA1);
> -	memcpy(cmd.params.pcrextend_in.digest, hash, TPM_DIGEST_SIZE);
> +	size = size + sizeof(cmd.params.pcrextend_in.auth_area);
> +
> +	cmd.params.pcrextend_in.digests.count =
> +		cpu_to_be32(digest_list->count);
> +	size = size + sizeof(cmd.params.pcrextend_in.digests.count);
> +	marker = &cmd.params.pcrextend_in.digests.digests[0];
> +
> +	for (i = 0; i < digest_list->count; i++) {
> +		for (j = 0; j < ARRAY_SIZE(tpm2_hash_map); j++) {
> +
> +			if (digest_list->digests[i].alg_id !=
> +			    tpm2_hash_map[j].tpm_id)
> +				continue;
> +
> +			halg_size = sizeof(digest_list->digests[i].alg_id);
> +			halg = cpu_to_be16(digest_list->digests[i].alg_id);
> +			memcpy(marker, &halg, halg_size);
> +			marker = marker + halg_size;
> +			size = size + halg_size;
> +
> +			memcpy(marker, &digest_list->digests[i].digest,
> +			       hash_digest_size[tpm2_hash_map[j].crypto_id]);
> +			marker = marker +
> +				hash_digest_size[tpm2_hash_map[j].crypto_id];
> +			size = size +
> +				hash_digest_size[tpm2_hash_map[j].crypto_id];
> +		}
> +	}
>  
> +	cmd.header.in.length = cpu_to_be32(size);
>  	rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd), 0,
>  			      "attempting extend a PCR value");
>  
> diff --git a/drivers/char/tpm/tpm2.h b/drivers/char/tpm/tpm2.h
> index 919fb05..0b1a107 100644
> --- a/drivers/char/tpm/tpm2.h
> +++ b/drivers/char/tpm/tpm2.h
> @@ -74,6 +74,22 @@ struct tcg_pcr_event2 {
>  	struct tcg_event_field		event;
>  } __packed;
>  
> +/* Auth Area Structure. */
> +struct tpm2_null_auth_area {
> +	__be32		handle;
> +	__be16		nonce_size;
> +	u8		attributes;
> +	__be16		auth_size;
> +} __packed;
> +
> +/* Crypto agile extend format. */
> +struct tpm2_pcr_extend_in {
> +	__be32				pcr_idx;
> +	__be32				auth_area_size;
> +	struct tpm2_null_auth_area	auth_area;
> +	struct tpml_digest_values	digests;
> +} __packed;
> +
>  struct tpm2_get_cap_in {
>  	__be32 cap_id;
>  	__be32 property_id;
> @@ -108,6 +124,8 @@ struct tpm2_get_cap_out {
>  extern const struct seq_operations tpm2_binary_b_measurments_seqops;
>  
>  extern int tpm2_get_active_pcr_banks(struct tpm_chip *chip);
> +extern int tpm2_pcr_extend(struct tpm_chip *chip, int pcr_idx,
> +			   struct tpml_digest_values *digest_values);
>  extern int tpm2_get_capability(struct tpm_chip *chip, struct tpm2_get_cap_in
>  	*cap_in, struct tpm2_get_cap_out *cap_out);
>  
> -- 
> 2.5.0
> 

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