linux-kernel - Re: [tpmdd-devel] [PATCH] tpm: fix type issues in tpm

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Message-Id: <58948A45.5020105@linux.vnet.ibm.com>
Date:   Fri, 3 Feb 2017 19:18:53 +0530
From:   Nayna <nayna@...ux.vnet.ibm.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        tpmdd-devel@...ts.sourceforge.net
Cc:     open list <linux-kernel@...r.kernel.org>,
        linux-security-module@...r.kernel.org
Subject: Re: [tpmdd-devel] [PATCH] tpm: fix type issues in tpm_getcap()



On 02/01/2017 11:23 PM, Jarkko Sakkinen wrote:
> There are two type issues associated with tpm_getcap().
>
> You must not do arithmetic with __be32 or __le32 types because sometimes
> it results incorrect results. Calculations must be done only with data
> that is in CPU byte order. This commit migrates tpm_getcap() to struct
> tpm_buf in order to sort out these issues.
>
> The second issue is with struct cap_t as the size of the type bool is
> assumed to be one byte. This commit sorts out the issue by changing the
> type to u8.
>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> ---
> v2:
> - Use struct tpm_buf.
> - Merge the type change of 'owned' to this patch.
>   drivers/char/tpm/tpm-interface.c | 33 ++++++++++++++++++---------------
>   drivers/char/tpm/tpm.h           | 15 +--------------
>   2 files changed, 19 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 423938e..7af1e8c 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -480,31 +480,34 @@ static const struct tpm_input_header tpm_getcap_header = {
>   ssize_t tpm_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
>   		   const char *desc, size_t min_cap_length)
>   {
> -	struct tpm_cmd_t tpm_cmd;
> +	struct tpm_buf buf;
>   	int rc;
>
> -	tpm_cmd.header.in = tpm_getcap_header;
> +	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_CAP);

I think there is a problem here of twice converting to be32 for both tag 
and ordinal.

Both TPM_ORD_GET_CAP and TPM_TAG_RQU_COMMAND are already defined as:
#define TPM_ORD_GET_CAP cpu_to_be32(101)
#define TPM_TAG_RQU_COMMAND  cpu_to_be16(193)

and again converted to BE in tpm_buf_init().

Thanks & Regards,
    - Nayna

> +	if (rc)
> +		return rc;
> +
>   	if (subcap_id == TPM_CAP_VERSION_1_1 ||
>   	    subcap_id == TPM_CAP_VERSION_1_2) {
> -		tpm_cmd.params.getcap_in.cap = cpu_to_be32(subcap_id);
> -		/*subcap field not necessary */
> -		tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(0);
> -		tpm_cmd.header.in.length -= cpu_to_be32(sizeof(__be32));
> +		tpm_buf_append_u32(&buf, subcap_id);
> +		tpm_buf_append_u32(&buf, 0);
>   	} else {
>   		if (subcap_id == TPM_CAP_FLAG_PERM ||
>   		    subcap_id == TPM_CAP_FLAG_VOL)
> -			tpm_cmd.params.getcap_in.cap =
> -				cpu_to_be32(TPM_CAP_FLAG);
> +			tpm_buf_append_u32(&buf, TPM_CAP_FLAG);
>   		else
> -			tpm_cmd.params.getcap_in.cap =
> -				cpu_to_be32(TPM_CAP_PROP);
> -		tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(4);
> -		tpm_cmd.params.getcap_in.subcap = cpu_to_be32(subcap_id);
> +			tpm_buf_append_u32(&buf, TPM_CAP_PROP);
> +
> +		tpm_buf_append_u32(&buf, 4);
> +		tpm_buf_append_u32(&buf, subcap_id);
>   	}
> -	rc = tpm_transmit_cmd(chip, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE,
> -			      min_cap_length, 0, desc);
> +
> +	rc = tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, min_cap_length, 0,
> +			      desc);
>   	if (!rc)
> -		*cap = tpm_cmd.params.getcap_out.cap;
> +		*cap = *(cap_t *)&buf.data[TPM_HEADER_SIZE + 4];
> +
> +	tpm_buf_destroy(&buf);
>   	return rc;
>   }
>   EXPORT_SYMBOL_GPL(tpm_getcap);
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index bff37be..709e7d4 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -281,7 +281,7 @@ struct permanent_flags_t {
>   typedef union {
>   	struct	permanent_flags_t perm_flags;
>   	struct	stclear_flags_t	stclear_flags;
> -	bool	owned;
> +	u8	owned;
>   	__be32	num_pcrs;
>   	struct	tpm_version_t	tpm_version;
>   	struct	tpm_version_1_2_t tpm_version_1_2;
> @@ -307,17 +307,6 @@ enum tpm_sub_capabilities {
>   	TPM_CAP_PROP_TIS_DURATION = 0x120,
>   };
>
> -struct	tpm_getcap_params_in {
> -	__be32	cap;
> -	__be32	subcap_size;
> -	__be32	subcap;
> -} __packed;
> -
> -struct	tpm_getcap_params_out {
> -	__be32	cap_size;
> -	cap_t	cap;
> -} __packed;
> -
>   struct	tpm_readpubek_params_out {
>   	u8	algorithm[4];
>   	u8	encscheme[2];
> @@ -367,10 +356,8 @@ struct tpm_startup_in {
>   } __packed;
>
>   typedef union {
> -	struct	tpm_getcap_params_out getcap_out;
>   	struct	tpm_readpubek_params_out readpubek_out;
>   	u8	readpubek_out_buffer[sizeof(struct tpm_readpubek_params_out)];
> -	struct	tpm_getcap_params_in getcap_in;
>   	struct	tpm_pcrread_in	pcrread_in;
>   	struct	tpm_pcrread_out	pcrread_out;
>   	struct	tpm_pcrextend_in pcrextend_in;
>