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TPM: workaround to enforce PCR updates across suspends

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Add a workaround for TPM's which fail to flush last written
PCR values in a TPM_SaveState, in preparation for suspend.

Signed-off-by: David Safford <safford@watson.ibm.com>
Acked-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
This commit is contained in:
Rajiv Andrade
2010-03-25 00:55:32 -03:00
committed by James Morris
parent 310de047ee
commit 225a9be24d
2 changed files with 50 additions and 7 deletions
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47
drivers/char/tpm/tpm.c
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@@ -1067,6 +1067,27 @@ void tpm_remove_hardware(struct device *dev)
}
EXPORT_SYMBOL_GPL(tpm_remove_hardware);
#define TPM_ORD_SAVESTATE cpu_to_be32(152)
#define SAVESTATE_RESULT_SIZE 10
static struct tpm_input_header savestate_header = {
.tag = TPM_TAG_RQU_COMMAND,
.length = cpu_to_be32(10),
.ordinal = TPM_ORD_SAVESTATE
};
/* Bug workaround - some TPM's don't flush the most
* recently changed pcr on suspend, so force the flush
* with an extend to the selected _unused_ non-volatile pcr.
*/
static int tpm_suspend_pcr;
static int __init tpm_suspend_setup(char *str)
{
get_option(&str, &tpm_suspend_pcr);
return 1;
}
__setup("tpm_suspend_pcr=", tpm_suspend_setup);
/*
* We are about to suspend. Save the TPM state
* so that it can be restored.
@@ -1074,17 +1095,29 @@ EXPORT_SYMBOL_GPL(tpm_remove_hardware);
int tpm_pm_suspend(struct device *dev, pm_message_t pm_state)
{
struct tpm_chip *chip = dev_get_drvdata(dev);
u8 savestate[] = {
0, 193, /* TPM_TAG_RQU_COMMAND */
0, 0, 0, 10, /* blob length (in bytes) */
0, 0, 0, 152 /* TPM_ORD_SaveState */
};
struct tpm_cmd_t cmd;
int rc;
u8 dummy_hash[TPM_DIGEST_SIZE] = { 0 };
if (chip == NULL)
return -ENODEV;
tpm_transmit(chip, savestate, sizeof(savestate));
return 0;
/* for buggy tpm, flush pcrs with extend to selected dummy */
if (tpm_suspend_pcr) {
cmd.header.in = pcrextend_header;
cmd.params.pcrextend_in.pcr_idx = cpu_to_be32(tpm_suspend_pcr);
memcpy(cmd.params.pcrextend_in.hash, dummy_hash,
TPM_DIGEST_SIZE);
rc = transmit_cmd(chip, &cmd, EXTEND_PCR_RESULT_SIZE,
"extending dummy pcr before suspend");
}
/* now do the actual savestate */
cmd.header.in = savestate_header;
rc = transmit_cmd(chip, &cmd, SAVESTATE_RESULT_SIZE,
"sending savestate before suspend");
return rc;
}
EXPORT_SYMBOL_GPL(tpm_pm_suspend);