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tpm: add TPM2_PCR_Read command support

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Add support for the TPM2_PCR_Read command.

Change the command file and the help accordingly.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
This commit is contained in:
Miquel Raynal 2018-05-15 11:57:16 +02:00 committed by Tom Rini
parent 6284be5a90
commit 1c4ea8f496
3 changed files with 98 additions and 0 deletions
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43
cmd/tpm-v2.c
View file

@ -106,6 +106,44 @@ static int do_tpm2_pcr_extend(cmd_tbl_t *cmdtp, int flag, int argc,
return report_return_code(rc);
}
static int do_tpm_pcr_read(cmd_tbl_t *cmdtp, int flag, int argc,
char * const argv[])
{
struct udevice *dev;
struct tpm_chip_priv *priv;
u32 index, rc;
unsigned int updates;
void *data;
int ret;
if (argc != 3)
return CMD_RET_USAGE;
ret = uclass_first_device_err(UCLASS_TPM, &dev);
if (ret)
return ret;
priv = dev_get_uclass_priv(dev);
if (!priv)
return -EINVAL;
index = simple_strtoul(argv[1], NULL, 0);
if (index >= priv->pcr_count)
return -EINVAL;
data = map_sysmem(simple_strtoul(argv[2], NULL, 0), 0);
rc = tpm2_pcr_read(index, priv->pcr_select_min, data, &updates);
if (!rc) {
printf("PCR #%u content (%d known updates):\n", index, updates);
print_byte_string(data, TPM2_DIGEST_LEN);
}
unmap_sysmem(data);
return report_return_code(rc);
}
static cmd_tbl_t tpm2_commands[] = {
U_BOOT_CMD_MKENT(info, 0, 1, do_tpm_info, "", ""),
U_BOOT_CMD_MKENT(init, 0, 1, do_tpm_init, "", ""),
@ -113,6 +151,7 @@ static cmd_tbl_t tpm2_commands[] = {
U_BOOT_CMD_MKENT(self_test, 0, 1, do_tpm2_self_test, "", ""),
U_BOOT_CMD_MKENT(clear, 0, 1, do_tpm2_clear, "", ""),
U_BOOT_CMD_MKENT(pcr_extend, 0, 1, do_tpm2_pcr_extend, "", ""),
U_BOOT_CMD_MKENT(pcr_read, 0, 1, do_tpm_pcr_read, "", ""),
};
cmd_tbl_t *get_tpm_commands(unsigned int *size)
@ -148,4 +187,8 @@ U_BOOT_CMD(tpm, CONFIG_SYS_MAXARGS, 1, do_tpm, "Issue a TPMv2.x command",
" Extend PCR #<pcr> with digest at <digest_addr>.\n"
" <pcr>: index of the PCR\n"
" <digest_addr>: address of a 32-byte SHA256 digest\n"
"pcr_read <pcr> <digest_addr>\n"
" Read PCR #<pcr> to memory address <digest_addr>.\n"
" <pcr>: index of the PCR\n"
" <digest_addr>: address to store the a 32-byte SHA256 digest\n"
);

13
include/tpm-v2.h
View file

@ -164,4 +164,17 @@ u32 tpm2_clear(u32 handle, const char *pw, const ssize_t pw_sz);
*/
u32 tpm2_pcr_extend(u32 index, const uint8_t *digest);
/**
* Issue a TPM2_PCR_Read command.
*
* @idx Index of the PCR
* @idx_min_sz Minimum size in bytes of the pcrSelect array
* @data Output buffer for contents of the named PCR
* @updates Optional out parameter: number of updates for this PCR
*
* @return code of the operation
*/
u32 tpm2_pcr_read(u32 idx, unsigned int idx_min_sz, void *data,
unsigned int *updates);
#endif /* __TPM_V2_H */

42
lib/tpm-v2.c
View file

@ -115,3 +115,45 @@ u32 tpm2_pcr_extend(u32 index, const uint8_t *digest)
return tpm_sendrecv_command(command_v2, NULL, NULL);
}
u32 tpm2_pcr_read(u32 idx, unsigned int idx_min_sz, void *data,
unsigned int *updates)
{
u8 idx_array_sz = max(idx_min_sz, DIV_ROUND_UP(idx, 8));
u8 command_v2[COMMAND_BUFFER_SIZE] = {
tpm_u16(TPM2_ST_NO_SESSIONS), /* TAG */
tpm_u32(17 + idx_array_sz), /* 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 */
idx_array_sz, /* Array size for selection */
/* bitmap(idx) Selected PCR bitmap */
};
size_t response_len = COMMAND_BUFFER_SIZE;
u8 response[COMMAND_BUFFER_SIZE];
unsigned int pcr_sel_idx = idx / 8;
u8 pcr_sel_bit = BIT(idx % 8);
unsigned int counter = 0;
int ret;
if (pack_byte_string(command_v2, COMMAND_BUFFER_SIZE, "b",
17 + pcr_sel_idx, pcr_sel_bit))
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;
}