[U-Boot] [PATCH 17/18] tpm: add TPM2_HierarchyChangeAuth command support

[Miquel Raynal]

Add support for the TPM2_HierarchyChangeAuth command.

Change the command file and the help accordingly.

Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>
---
 cmd/tpm.c     | 34 ++++++++++++++++++++++++++++++++++
 include/tpm.h | 14 ++++++++++++++
 lib/tpm.c     | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 95 insertions(+)

diff --git a/cmd/tpm.c b/cmd/tpm.c
index 533da2d2ac..3c486c313b 100644
--- a/cmd/tpm.c
+++ b/cmd/tpm.c
@@ -555,6 +555,36 @@ static int do_tpm_force_clear(cmd_tbl_t *cmdtp, int flag,
 	return report_return_code(tpm_force_clear(handle, pw, pw_sz));
 }
 
+static int do_tpm_change_auth(cmd_tbl_t *cmdtp, int flag,
+			      int argc, char *const argv[])
+{
+	u32 handle;
+	const char *newpw = argv[2];
+	const char *oldpw = (argc == 3) ? NULL : argv[3];
+	const ssize_t newpw_sz = strlen(newpw);
+	const ssize_t oldpw_sz = oldpw ? strlen(oldpw) : 0;
+
+	if (argc < 3 || argc > 4)
+		return CMD_RET_USAGE;
+
+	if (newpw_sz > TPM2_DIGEST_LENGTH || oldpw_sz > TPM2_DIGEST_LENGTH)
+		return -EINVAL;
+
+	if (!strcasecmp("TPM2_RH_LOCKOUT", argv[1]))
+		handle = TPM2_RH_LOCKOUT;
+	else if (!strcasecmp("TPM2_RH_ENDORSEMENT", argv[1]))
+		handle = TPM2_RH_ENDORSEMENT;
+	else if (!strcasecmp("TPM2_RH_OWNER", argv[1]))
+		handle = TPM2_RH_OWNER;
+	else if (!strcasecmp("TPM2_RH_PLATFORM", argv[1]))
+		handle = TPM2_RH_PLATFORM;
+	else
+		return CMD_RET_USAGE;
+
+	return report_return_code(tpm2_change_auth(handle, newpw, newpw_sz,
+						   oldpw, oldpw_sz));
+}
+
 #define TPM_COMMAND_NO_ARG(cmd)				\
 static int do_##cmd(cmd_tbl_t *cmdtp, int flag,		\
 		int argc, char * const argv[])		\
@@ -959,6 +989,8 @@ static cmd_tbl_t tpm_commands[] = {
 			 do_tpm_dam_set_parameters, "", ""),
 	U_BOOT_CMD_MKENT(force_clear, 0, 1,
 			 do_tpm_force_clear, "", ""),
+	U_BOOT_CMD_MKENT(change_auth, 0, 1,
+			 do_tpm_change_auth, "", ""),
 	U_BOOT_CMD_MKENT(physical_enable, 0, 1,
 			 do_tpm_physical_enable, "", ""),
 	U_BOOT_CMD_MKENT(physical_disable, 0, 1,
@@ -1060,6 +1092,8 @@ U_BOOT_CMD(tpm, CONFIG_SYS_MAXARGS, 1, do_tpm,
 "  force_clear [<type>]\n"
 "    - Issue TPM_[Force]Clear command, with <type> one of (TPMv2 only):\n"
 "          * TPM2_RH_LOCKOUT, TPM2_RH_PLATFORM.\n"
+"  change_auth <new_pw> [<old_pw>]\n"
+"    - Change the hierarchy authorizations (TPMv2 only).\n"
 "  tsc_physical_presence flags\n"
 "    - Set TPM device's Physical Presence flags to <flags>.\n"
 "The Capability Commands:\n"
diff --git a/include/tpm.h b/include/tpm.h
index 4d062584f9..cc63f06634 100644
--- a/include/tpm.h
+++ b/include/tpm.h
@@ -60,6 +60,7 @@ enum tpm2_command_codes {
 	TPM2_CC_SELF_TEST	= 0x0143,
 	TPM2_CC_CLEAR		= 0x0126,
 	TPM2_CC_CLEARCONTROL	= 0x0127,
+	TPM2_CC_HIERCHANGEAUTH	= 0x0129,
 	TPM2_CC_DAM_RESET	= 0x0139,
 	TPM2_CC_DAM_PARAMETERS	= 0x013A,
 	TPM2_CC_GET_CAPABILITY	= 0x017A,
@@ -630,6 +631,19 @@ int tpm2_dam_set_parameters(const char *pw, const ssize_t pw_sz,
  */
 int tpm_force_clear(u32 handle, const char *pw, const ssize_t pw_sz);
 
+/**
+ * Issue a TPM2_HierarchyChangeAuthorization command.
+ *
+ * @param handle	Handle
+ * @param newpw		New password
+ * @param newpw_sz	Length of the new password
+ * @param oldpw		Old password
+ * @param oldpw_sz	Length of the old password
+ * @return return code of the operation
+ */
+int tpm2_change_auth(u32 handle, const char *newpw, const ssize_t newpw_sz,
+		     const char *oldpw, const ssize_t oldpw_sz);
+
 /**
  * Issue a TPM_PhysicalEnable command.
  *
diff --git a/lib/tpm.c b/lib/tpm.c
index 1e064e6ff1..f09b9ce9eb 100644
--- a/lib/tpm.c
+++ b/lib/tpm.c
@@ -835,6 +835,53 @@ int tpm_force_clear(u32 handle, const char *pw, const ssize_t pw_sz)
 	return tpm_sendrecv_command(command_v2, NULL, NULL);
 }
 
+int tpm2_change_auth(u32 handle, const char *newpw, const ssize_t newpw_sz,
+		     const char *oldpw, const ssize_t oldpw_sz)
+{
+	unsigned int offset = 27;
+	u8 command_v2[COMMAND_BUFFER_SIZE] = {
+		STRINGIFY16(TPM2_ST_SESSIONS),	/* TAG */
+		STRINGIFY32(offset + oldpw_sz + 2 + newpw_sz), /* Command len */
+		STRINGIFY32(TPM2_CC_HIERCHANGEAUTH), /* Command code */
+
+		/* HANDLE */
+		STRINGIFY32(handle),		/* TPM resource handle */
+
+		/* AUTH_SESSION */
+		STRINGIFY32(9 + oldpw_sz),	/* Authorization size */
+		STRINGIFY32(TPM2_RS_PW),	/* Session handle */
+		STRINGIFY16(0),			/* Size of <nonce> */
+						/* <nonce> (if any) */
+		0,				/* Attributes: Cont/Excl/Rst */
+		STRINGIFY16(oldpw_sz)		/* Size of <hmac/password> */
+		/* STRING(oldpw)		   <hmac/password> (if any) */
+
+		/* TPM2B_AUTH (TPM2B_DIGEST) */
+		/* STRINGIFY16(newpw_sz)	   Digest size, new pw length */
+		/* STRING(newpw)		   Digest buffer, new pw */
+	};
+	int ret;
+
+	if (!is_tpmv2)
+		return TPM_LIB_ERROR;
+
+	/*
+	 * Fill the command structure starting from the first buffer:
+	 *     - the old password (if any)
+	 *     - size of the new password
+	 *     - new password
+	 */
+	ret = pack_byte_string(command_v2, sizeof(command_v2), "sws",
+			       offset, oldpw, oldpw_sz,
+			       offset + oldpw_sz, newpw_sz,
+			       offset + oldpw_sz + 2, newpw, newpw_sz);
+	offset += oldpw_sz + 2 + newpw_sz;
+	if (ret)
+		return TPM_LIB_ERROR;
+
+	return tpm_sendrecv_command(command_v2, NULL, NULL);
+}
+
 uint32_t tpm_physical_enable(void)
 {
 	const uint8_t command[10] = {
-- 
2.14.1