From 63af92e837f3d7c21ab5fc4a96ffcbf202efaf90 Mon Sep 17 00:00:00 2001
From: Simon Glass <sjg@chromium.org>
Date: Sat, 6 Feb 2021 14:23:42 -0700
Subject: [PATCH] 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>
---
 include/tpm-v2.h | 13 +++++++++++++
 lib/tpm-v2.c     | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/include/tpm-v2.h b/include/tpm-v2.h
index fa3296a7b0..df67a196cf 100644
--- a/include/tpm-v2.h
+++ b/include/tpm-v2.h
@@ -237,6 +237,7 @@ enum tpm2_handles {
 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 @@ enum tpm2_return_codes {
 	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_get_random(struct udevice *dev, void *data, u32 count);
  */
 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 b796004930..235f8c20d4 100644
--- a/lib/tpm-v2.c
+++ b/lib/tpm-v2.c
@@ -624,3 +624,38 @@ u32 tpm2_write_lock(struct udevice *dev, u32 index)
 
 	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;
+}