[PATCH 11/11] tpm: Allow disabling platform hierarchy with TPM2

[Simon Glass]

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 at chromium.org>
---

 include/tpm-v2.h | 12 ++++++++++++
 lib/tpm-v2.c     | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/include/tpm-v2.h b/include/tpm-v2.h
index 1ca1e7e2011..20b08f62a20 100644
--- a/include/tpm-v2.h
+++ b/include/tpm-v2.h
@@ -235,6 +235,7 @@ 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,
@@ -582,4 +583,15 @@ 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 6bddafcc777..6af6a8a5ba8 100644
--- a/lib/tpm-v2.c
+++ b/lib/tpm-v2.c
@@ -619,3 +619,38 @@ 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;
+}
-- 
2.30.0.284.gd98b1dd5eaa7-goog