Re: [PATCH] keys, trusted: select TPM2 hash algorithm

[Jarkko Sakkinen]

On Sat, Oct 24, 2015 at 03:42:42PM +0300, Jarkko Sakkinen wrote:
> Added 'hashalg=' option for selecting the hash algorithm.
> 
> Currently available options are:
> 
> * sha1
> * sha256
> * sha384
> * sha512
> * sm3_256
> 
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>

Things that came to mind after sending this:

* Documentation update is needed.
* Maybe it would be a good idea to return -EINVAL in the following
  conditions:
  * TPM1 chip
  * Explicit hashalg option where hashalg is something different than
    sha1.

Also one question: should I split this into three patches:

* Support for 'hashalg' in drivers/char/tpm.
* Parsing of hashalg in security/keys.
* Documentation update.

Anyway, this patch is good for testing. No functional updates are
needed except maybe that update for TPM1 chips.

/Jarkko

> ---
>  drivers/char/tpm/tpm.h      |  5 ++++-
>  drivers/char/tpm/tpm2-cmd.c | 34 ++++++++++++++++++++++++++++++++++
>  include/keys/trusted-type.h |  2 ++
>  security/keys/trusted.c     |  8 +++++++-
>  4 files changed, 47 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index a4257a3..4c18f46 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -92,7 +92,10 @@ enum tpm2_algorithms {
>  	TPM2_ALG_SHA1		= 0x0004,
>  	TPM2_ALG_KEYEDHASH	= 0x0008,
>  	TPM2_ALG_SHA256		= 0x000B,
> -	TPM2_ALG_NULL		= 0x0010
> +	TPM2_ALG_SHA384		= 0x000C,
> +	TPM2_ALG_SHA512		= 0x000D,
> +	TPM2_ALG_NULL		= 0x0010,
> +	TPM2_ALG_SM3_256	= 0x0012,
>  };
>  
>  enum tpm2_command_codes {
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index bd7039f..0704bd6 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -104,6 +104,22 @@ struct tpm2_cmd {
>  	union tpm2_cmd_params	params;
>  } __packed;
>  
> +struct tpm2_hashalg {
> +	char	name[MAX_HASHALG_SIZE];
> +	u32	id;
> +};
> +
> +struct tpm2_hashalg tpm2_hashalg_map[] = {
> +	{"sha1", TPM2_ALG_SHA1},
> +	{"sha256", TPM2_ALG_SHA256},
> +	{"sm3_256", TPM2_ALG_SM3_256},
> +	{"sha384", TPM2_ALG_SHA384},
> +	{"sha512", TPM2_ALG_SHA512},
> +};
> +
> +#define TPM2_HASHALG_COUNT \
> +	(sizeof(tpm2_hashalg_map) / sizeof(tpm2_hashalg_map[1]))
> +
>  /*
>   * Array with one entry per ordinal defining the maximum amount
>   * of time the chip could take to return the result. The values
> @@ -429,8 +445,26 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
>  {
>  	unsigned int blob_len;
>  	struct tpm_buf buf;
> +	u32 hashalg = TPM2_ALG_SHA256;
> +	int i;
>  	int rc;
>  
> +	if (strlen(options->hashalg) > 0) {
> +		for (i = 0; i < TPM2_HASHALG_COUNT; i++) {
> +			if (!strcmp(options->hashalg,
> +				    tpm2_hashalg_map[i].name)) {
> +				hashalg = tpm2_hashalg_map[i].id;
> +				dev_dbg(chip->pdev, "%s: hashalg: %s 0x%08X\n",
> +					__func__, tpm2_hashalg_map[i].name,
> +					hashalg);
> +				break;
> +			}
> +		}
> +
> +		if (i == TPM2_HASHALG_COUNT)
> +			return -EINVAL;
> +	}
> +
>  	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
>  	if (rc)
>  		return rc;
> diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h
> index f91ecd9..a545733 100644
> --- a/include/keys/trusted-type.h
> +++ b/include/keys/trusted-type.h
> @@ -18,6 +18,7 @@
>  #define MAX_KEY_SIZE			128
>  #define MAX_BLOB_SIZE			512
>  #define MAX_PCRINFO_SIZE		64
> +#define MAX_HASHALG_SIZE		16
>  
>  struct trusted_key_payload {
>  	struct rcu_head rcu;
> @@ -36,6 +37,7 @@ struct trusted_key_options {
>  	uint32_t pcrinfo_len;
>  	unsigned char pcrinfo[MAX_PCRINFO_SIZE];
>  	int pcrlock;
> +	unsigned char hashalg[MAX_HASHALG_SIZE];
>  };
>  
>  extern struct key_type key_type_trusted;
> diff --git a/security/keys/trusted.c b/security/keys/trusted.c
> index d3633cf..9e7564d 100644
> --- a/security/keys/trusted.c
> +++ b/security/keys/trusted.c
> @@ -710,7 +710,8 @@ enum {
>  	Opt_err = -1,
>  	Opt_new, Opt_load, Opt_update,
>  	Opt_keyhandle, Opt_keyauth, Opt_blobauth,
> -	Opt_pcrinfo, Opt_pcrlock, Opt_migratable
> +	Opt_pcrinfo, Opt_pcrlock, Opt_migratable,
> +	Opt_hashalg,
>  };
>  
>  static const match_table_t key_tokens = {
> @@ -723,6 +724,7 @@ static const match_table_t key_tokens = {
>  	{Opt_pcrinfo, "pcrinfo=%s"},
>  	{Opt_pcrlock, "pcrlock=%s"},
>  	{Opt_migratable, "migratable=%s"},
> +	{Opt_hashalg, "hashalg=%s"},
>  	{Opt_err, NULL}
>  };
>  
> @@ -787,6 +789,10 @@ static int getoptions(char *c, struct trusted_key_payload *pay,
>  				return -EINVAL;
>  			opt->pcrlock = lock;
>  			break;
> +		case Opt_hashalg:
> +			strncpy(opt->hashalg, args[0].from,
> +				MAX_HASHALG_SIZE - 1);
> +			break;
>  		default:
>  			return -EINVAL;
>  		}
> -- 
> 2.5.0
> 
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