TPM: workaround to enforce PCR updates across suspends
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>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index d80930d..e0df679 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -99,6 +99,7 @@
SWSUSP Software suspend (hibernation) is enabled.
SUSPEND System suspend states are enabled.
FTRACE Function tracing enabled.
+ TPM TPM drivers are enabled.
TS Appropriate touchscreen support is enabled.
UMS USB Mass Storage support is enabled.
USB USB support is enabled.
@@ -2619,6 +2620,15 @@
tp720= [HW,PS2]
+ tpm_suspend_pcr=[HW,TPM]
+ Format: integer pcr id
+ Specify that at suspend time, the tpm driver
+ should extend the specified pcr with zeros,
+ as a workaround for some chips which fail to
+ flush the last written pcr on TPM_SaveState.
+ This will guarantee that all the other pcrs
+ are saved.
+
trace_buf_size=nn[KMG]
[FTRACE] will set tracing buffer size.
diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index f06bb37..5c447c9 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -1067,6 +1067,27 @@
}
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 @@
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);