tpm: Allow disabling platform hierarchy with TPM2
With TPM2 we don't actually lock the TPM once verified boot is finished.
Instead we disable the platform hierarchy which serves the same purpose.
Add an implementation of this so we can safely boot into the kernel.
Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/include/tpm-v2.h b/include/tpm-v2.h
index fa3296a..df67a19 100644
--- a/include/tpm-v2.h
+++ b/include/tpm-v2.h
@@ -237,6 +237,7 @@
enum tpm2_command_codes {
TPM2_CC_STARTUP = 0x0144,
TPM2_CC_SELF_TEST = 0x0143,
+ TPM2_CC_HIER_CONTROL = 0x0121,
TPM2_CC_CLEAR = 0x0126,
TPM2_CC_CLEARCONTROL = 0x0127,
TPM2_CC_HIERCHANGEAUTH = 0x0129,
@@ -274,6 +275,7 @@
TPM2_RC_COMMAND_CODE = TPM2_RC_VER1 + 0x0043,
TPM2_RC_AUTHSIZE = TPM2_RC_VER1 + 0x0044,
TPM2_RC_AUTH_CONTEXT = TPM2_RC_VER1 + 0x0045,
+ TPM2_RC_NV_DEFINED = TPM2_RC_VER1 + 0x004c,
TPM2_RC_NEEDS_TEST = TPM2_RC_VER1 + 0x0053,
TPM2_RC_WARN = 0x0900,
TPM2_RC_TESTING = TPM2_RC_WARN + 0x000A,
@@ -584,4 +586,15 @@
*/
u32 tpm2_write_lock(struct udevice *dev, u32 index);
+/**
+ * Disable access to any platform data
+ *
+ * This can be called to close off access to the firmware data in the data,
+ * before calling the kernel.
+ *
+ * @dev TPM device
+ * @return code of the operation
+ */
+u32 tpm2_disable_platform_hierarchy(struct udevice *dev);
+
#endif /* __TPM_V2_H */
diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
index b796004..235f8c2 100644
--- a/lib/tpm-v2.c
+++ b/lib/tpm-v2.c
@@ -624,3 +624,38 @@
return tpm_sendrecv_command(dev, command_v2, NULL, NULL);
}
+
+u32 tpm2_disable_platform_hierarchy(struct udevice *dev)
+{
+ struct tpm_chip_priv *priv = dev_get_uclass_priv(dev);
+ u8 command_v2[COMMAND_BUFFER_SIZE] = {
+ /* header 10 bytes */
+ tpm_u16(TPM2_ST_SESSIONS), /* TAG */
+ tpm_u32(10 + 4 + 13 + 5), /* Length */
+ tpm_u32(TPM2_CC_HIER_CONTROL), /* Command code */
+
+ /* 4 bytes */
+ tpm_u32(TPM2_RH_PLATFORM), /* Primary platform seed */
+
+ /* session header 9 bytes */
+ tpm_u32(9), /* Header size */
+ tpm_u32(TPM2_RS_PW), /* Password authorisation */
+ tpm_u16(0), /* nonce_size */
+ 0, /* session_attrs */
+ tpm_u16(0), /* auth_size */
+
+ /* payload 5 bytes */
+ tpm_u32(TPM2_RH_PLATFORM), /* Hierarchy to disable */
+ 0, /* 0=disable */
+ };
+ int ret;
+
+ ret = tpm_sendrecv_command(dev, command_v2, NULL, NULL);
+ log_info("ret=%s, %x\n", dev->name, ret);
+ if (ret)
+ return ret;
+
+ priv->plat_hier_disabled = true;
+
+ return 0;
+}