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From: "Daniel P. Smith" <dpsmith@apertussolutions.com>
To: xen-devel@lists.xenproject.org
Subject: Re: [PATCH v2 09/13] vtpmmgr: Support GetRandom passthrough on TPM 2.0
Date: Mon, 10 May 2021 08:51:38 -0400	[thread overview]
Message-ID: <acbe24ac-0702-ebe3-1a6b-7f5899d97f79@apertussolutions.com> (raw)
In-Reply-To: <20210506135923.161427-10-jandryuk@gmail.com>

On 5/6/21 9:59 AM, Jason Andryuk wrote:
> GetRandom passthrough currently fails when using vtpmmgr with a hardware
> TPM 2.0.
> vtpmmgr (8): INFO[VTPM]: Passthrough: TPM_GetRandom
> vtpm (12): vtpm_cmd.c:120: Error: TPM_GetRandom() failed with error code (30)
> 
> When running on TPM 2.0 hardware, vtpmmgr needs to convert the TPM 1.2
> TPM_ORD_GetRandom into a TPM2 TPM_CC_GetRandom command.  Besides the
> differing ordinal, the TPM 1.2 uses 32bit sizes for the request and
> response (vs. 16bit for TPM2).
> 
> Place the random output directly into the tpmcmd->resp and build the
> packet around it.  This avoids bouncing through an extra buffer, but the
> header has to be written after grabbing the random bytes so we have the
> number of bytes to include in the size.
> 
> Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
> 
> ---
> v2:
> Add bounds and size checks
> Whitespace fixup
> ---

Reviewed by: Daniel P. Smith <dpsmith@apertussolutions.com>

>  stubdom/vtpmmgr/marshal.h          | 15 ++++++++
>  stubdom/vtpmmgr/vtpm_cmd_handler.c | 61 +++++++++++++++++++++++++++++-
>  2 files changed, 75 insertions(+), 1 deletion(-)
> 
> diff --git a/stubdom/vtpmmgr/marshal.h b/stubdom/vtpmmgr/marshal.h
> index dce19c6439..f1037a7976 100644
> --- a/stubdom/vtpmmgr/marshal.h
> +++ b/stubdom/vtpmmgr/marshal.h
> @@ -890,6 +890,15 @@ inline int sizeof_TPM_AUTH_SESSION(const TPM_AUTH_SESSION* auth) {
>  	return rv;
>  }
>  
> +static
> +inline int sizeof_TPM_RQU_HEADER(BYTE* ptr) {
> +	int rv = 0;
> +	rv += sizeof_UINT16(ptr);
> +	rv += sizeof_UINT32(ptr);
> +	rv += sizeof_UINT32(ptr);
> +	return rv;
> +}
> +
>  static
>  inline BYTE* pack_TPM_RQU_HEADER(BYTE* ptr,
>  		TPM_TAG tag,
> @@ -920,8 +929,14 @@ inline int unpack3_TPM_RQU_HEADER(BYTE* ptr, UINT32* pos, UINT32 max,
>  		unpack3_UINT32(ptr, pos, max, ord);
>  }
>  
> +static
> +inline int sizeof_TPM_RQU_GetRandom(BYTE* ptr) {
> +	return sizeof_TPM_RQU_HEADER(ptr) + sizeof_UINT32(ptr);
> +}
> +
>  #define pack_TPM_RSP_HEADER(p, t, s, r) pack_TPM_RQU_HEADER(p, t, s, r)
>  #define unpack_TPM_RSP_HEADER(p, t, s, r) unpack_TPM_RQU_HEADER(p, t, s, r)
>  #define unpack3_TPM_RSP_HEADER(p, l, m, t, s, r) unpack3_TPM_RQU_HEADER(p, l, m, t, s, r)
> +#define sizeof_TPM_RSP_HEADER(p) sizeof_TPM_RQU_HEADER(p)
>  
>  #endif
> diff --git a/stubdom/vtpmmgr/vtpm_cmd_handler.c b/stubdom/vtpmmgr/vtpm_cmd_handler.c
> index 2ac14fae77..c879b24c13 100644
> --- a/stubdom/vtpmmgr/vtpm_cmd_handler.c
> +++ b/stubdom/vtpmmgr/vtpm_cmd_handler.c
> @@ -47,6 +47,7 @@
>  #include "vtpm_disk.h"
>  #include "vtpmmgr.h"
>  #include "tpm.h"
> +#include "tpm2.h"
>  #include "tpmrsa.h"
>  #include "tcg.h"
>  #include "mgmt_authority.h"
> @@ -772,6 +773,64 @@ static int vtpmmgr_permcheck(struct tpm_opaque *opq)
>  	return 1;
>  }
>  
> +TPM_RESULT vtpmmgr_handle_getrandom(struct tpm_opaque *opaque,
> +				    tpmcmd_t* tpmcmd)
> +{
> +	TPM_RESULT status = TPM_SUCCESS;
> +	TPM_TAG tag;
> +	UINT32 size;
> +	const int max_rand_size = TCPA_MAX_BUFFER_LENGTH -
> +				  sizeof_TPM_RQU_GetRandom(tpmcmd->req);
> +	UINT32 rand_offset;
> +	UINT32 rand_size;
> +	TPM_COMMAND_CODE ord;
> +	BYTE *p;
> +
> +	if (tpmcmd->req_len != sizeof_TPM_RQU_GetRandom(tpmcmd->req)) {
> +		status = TPM_BAD_PARAMETER;
> +		tag = TPM_TAG_RQU_COMMAND;
> +		goto abort_egress;
> +	}
> +
> +	p = unpack_TPM_RQU_HEADER(tpmcmd->req, &tag, &size, &ord);
> +
> +	if (!hw_is_tpm2()) {
> +		size = TCPA_MAX_BUFFER_LENGTH;
> +		TPMTRYRETURN(TPM_TransmitData(tpmcmd->req, tpmcmd->req_len,
> +					      tpmcmd->resp, &size));
> +		tpmcmd->resp_len = size;
> +
> +		return TPM_SUCCESS;
> +	}
> +
> +	/* TPM_GetRandom req: <header><uint32 num bytes> */
> +	unpack_UINT32(p, &rand_size);
> +
> +	/* Returning fewer bytes is acceptable per the spec. */
> +	if (rand_size > max_rand_size)
> +		rand_size = max_rand_size;
> +
> +	/* Call TPM2_GetRandom but return a TPM_GetRandom response. */
> +	/* TPM_GetRandom resp: <header><uint32 num bytes><num random bytes> */
> +	rand_offset = sizeof_TPM_RSP_HEADER(tpmcmd->resp) +
> +		      sizeof_UINT32(tpmcmd->resp);
> +
> +	TPMTRYRETURN(TPM2_GetRandom(&rand_size, tpmcmd->resp + rand_offset));
> +
> +	p = pack_TPM_RSP_HEADER(tpmcmd->resp, TPM_TAG_RSP_COMMAND,
> +				rand_offset + rand_size, status);
> +	p = pack_UINT32(p, rand_size);
> +	tpmcmd->resp_len = rand_offset + rand_size;
> +
> +	return status;
> +
> +abort_egress:
> +	tpmcmd->resp_len = VTPM_COMMAND_HEADER_SIZE;
> +	pack_TPM_RSP_HEADER(tpmcmd->resp, tag + 3, tpmcmd->resp_len, status);
> +
> +	return status;
> +}
> +
>  TPM_RESULT vtpmmgr_handle_cmd(
>  		struct tpm_opaque *opaque,
>  		tpmcmd_t* tpmcmd)
> @@ -842,7 +901,7 @@ TPM_RESULT vtpmmgr_handle_cmd(
>  		switch(ord) {
>  		case TPM_ORD_GetRandom:
>  			vtpmloginfo(VTPM_LOG_VTPM, "Passthrough: TPM_GetRandom\n");
> -			break;
> +			return vtpmmgr_handle_getrandom(opaque, tpmcmd);
>  		case TPM_ORD_PcrRead:
>  			vtpmloginfo(VTPM_LOG_VTPM, "Passthrough: TPM_PcrRead\n");
>  			// Quotes also need to be restricted to hide PCR values
> 



  parent reply	other threads:[~2021-05-10 12:51 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-06 13:59 [PATCH v2 00/13] vtpmmgr: Some fixes - still incomplete Jason Andryuk
2021-05-06 13:59 ` [PATCH v2 01/13] docs: Warn about incomplete vtpmmgr TPM 2.0 support Jason Andryuk
2021-05-06 13:59 ` [PATCH v2 02/13] vtpmmgr: Print error code to aid debugging Jason Andryuk
2021-05-06 13:59 ` [PATCH v2 03/13] stubom: newlib: Enable C99 formats for %z Jason Andryuk
2021-05-06 13:59 ` [PATCH v2 04/13] vtpmmgr: Allow specifying srk_handle for TPM2 Jason Andryuk
2021-05-06 21:35   ` Samuel Thibault
2021-05-10 11:56   ` Daniel P. Smith
2021-05-06 13:59 ` [PATCH v2 05/13] vtpmmgr: Move vtpmmgr_shutdown Jason Andryuk
2021-05-07 15:48   ` Daniel P. Smith
2021-05-06 13:59 ` [PATCH v2 06/13] vtpmmgr: Flush transient keys on shutdown Jason Andryuk
2021-05-10 12:12   ` Daniel P. Smith
2021-05-06 13:59 ` [PATCH v2 07/13] vtpmmgr: Flush all transient keys Jason Andryuk
2021-05-10 12:19   ` Daniel P. Smith
2021-05-06 13:59 ` [PATCH v2 08/13] vtpmmgr: Shutdown more gracefully Jason Andryuk
2021-05-06 14:04   ` Jason Andryuk
2021-05-10 12:42   ` Daniel P. Smith
2021-05-06 13:59 ` [PATCH v2 09/13] vtpmmgr: Support GetRandom passthrough on TPM 2.0 Jason Andryuk
2021-05-06 21:40   ` Samuel Thibault
2021-05-10 12:51   ` Daniel P. Smith [this message]
2021-05-06 13:59 ` [PATCH v2 10/13] vtpmmgr: Remove bogus cast from TPM2_GetRandom Jason Andryuk
2021-05-06 21:41   ` Samuel Thibault
2021-05-10 13:03   ` Daniel P. Smith
2021-05-06 13:59 ` [PATCH v2 11/13] vtpmmgr: Fix owner_auth & srk_auth parsing Jason Andryuk
2021-05-06 21:41   ` Samuel Thibault
2021-05-10 13:18   ` Daniel P. Smith
2021-05-06 13:59 ` [PATCH v2 12/13] vtpmmgr: Check req_len before unpacking command Jason Andryuk
2021-05-06 21:42   ` Samuel Thibault
2021-05-10 13:32   ` Daniel P. Smith
2021-05-06 13:59 ` [PATCH v2 13/13] vtpm: Correct timeout units and command duration Jason Andryuk
2021-05-06 21:52   ` Samuel Thibault
2021-05-10 13:40   ` Daniel P. Smith

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