[U-Boot] [PATCH v3 12/25] tpm: add TPM2_PCR_Read command support

[Simon Glass]

Hi Miquel,

On 2 May 2018 at 02:59, Miquel Raynal <miquel.raynal at bootlin.com> wrote:
> Add support for the TPM2_PCR_Read command.
>
> Change the command file and the help accordingly.
>
> Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>
> ---
>  cmd/tpm-v2.c     | 27 +++++++++++++++++++++++++++
>  include/tpm-v2.h | 11 +++++++++++
>  lib/tpm-v2.c     | 43 +++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 81 insertions(+)
>

Reviewed-by: Simon Glass <sjg at chromium.org>

nits below

> diff --git a/cmd/tpm-v2.c b/cmd/tpm-v2.c
> index 6e19adbfe6..a61d751b4a 100644
> --- a/cmd/tpm-v2.c
> +++ b/cmd/tpm-v2.c
> @@ -86,6 +86,28 @@ static int do_tpm2_pcr_extend(cmd_tbl_t *cmdtp, int flag, int argc,
>         return report_return_code(tpm2_pcr_extend(index, digest));
>  }
>
> +static int do_tpm_pcr_read(cmd_tbl_t *cmdtp, int flag, int argc,
> +                          char * const argv[])
> +{
> +       u32 index, rc;
> +       unsigned int updates;
> +       void *data;
> +
> +       if (argc != 3)
> +               return CMD_RET_USAGE;
> +
> +       index = simple_strtoul(argv[1], NULL, 0);
> +       data = (void *)simple_strtoul(argv[2], NULL, 0);

data = map_sysmem(simple...(), 0);

so that it works on sandbox.

[...]

> +/**
> + * Issue a TPM2_PCR_Read command.
> + *
> + * @param index                Index of the PCR
> + * @param data         Output buffer for contents of the named PCR
> + * @param updates      Optional out parameter: number of updates for this PCR
> + *
> + * @return return code of the operation

For new code we should use

@index: Index of the PCR
@data: Output ...
@updates: Optional ....
@return ..


> + */
> +u32 tpm2_pcr_read(u32 index, void *data, unsigned int *updates);
> +
>  #endif /* __TPM_V2_H */
> diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
> index 2696f8145d..d557b08f8b 100644
> --- a/lib/tpm-v2.c
> +++ b/lib/tpm-v2.c
> @@ -115,3 +115,46 @@ u32 tpm2_pcr_extend(u32 index, const uint8_t *digest)
>
>         return tpm_sendrecv_command(command_v2, NULL, NULL);
>  }
> +
> +u32 tpm2_pcr_read(u32 index, void *data, unsigned int *updates)
> +{
> +       u8 command_v2[COMMAND_BUFFER_SIZE] = {
> +               tpm_u16(TPM2_ST_NO_SESSIONS),   /* TAG */
> +               tpm_u32(20),                    /* Length */
> +               tpm_u32(TPM2_CC_PCR_READ),      /* Command code */
> +
> +               /* TPML_PCR_SELECTION */
> +               tpm_u32(1),                     /* Number of selections */
> +               tpm_u16(TPM2_ALG_SHA256),       /* Algorithm of the hash */
> +               3,                              /* Array size for selection */
> +               /* bitmap(index)                Selected PCR bitmap */
> +       };
> +       size_t response_len = COMMAND_BUFFER_SIZE;
> +       u8 response[COMMAND_BUFFER_SIZE];
> +       unsigned int counter = 0;
> +       u8 pcr_sel[3] = {};
> +       int ret;
> +
> +       if (index >= 24)

What is 24?

> +               return TPM_LIB_ERROR;
> +
> +       pcr_sel[index / 8] = BIT(index % 8);
> +       if (pack_byte_string(command_v2, COMMAND_BUFFER_SIZE, "bbb",
> +                            17, pcr_sel[0], 18, pcr_sel[1], 19, pcr_sel[2]))
> +               return TPM_LIB_ERROR;
> +
> +       ret = tpm_sendrecv_command(command_v2, response, &response_len);
> +       if (ret)
> +               return ret;
> +
> +       if (unpack_byte_string(response, response_len, "ds",
> +                              10, &counter,
> +                              response_len - TPM2_DIGEST_LEN, data,
> +                              TPM2_DIGEST_LEN))
> +               return TPM_LIB_ERROR;
> +
> +       if (updates)
> +               *updates = counter;
> +
> +       return 0;
> +}
> --
> 2.14.1
>

Regards,
Simon