[U-Boot] [PATCH v3 11/25] tpm: add TPM2_PCR_Extend command support

[Miquel Raynal]

Add support for the TPM2_PCR_Extend command.

Change the command file and the help accordingly.

Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>
---
 cmd/tpm-v2.c     | 17 +++++++++++++++++
 include/tpm-v2.h | 10 ++++++++++
 lib/tpm-v2.c     | 38 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 65 insertions(+)

diff --git a/cmd/tpm-v2.c b/cmd/tpm-v2.c
index 9f6a8fc0b6..6e19adbfe6 100644
--- a/cmd/tpm-v2.c
+++ b/cmd/tpm-v2.c
@@ -74,12 +74,25 @@ static int do_tpm2_clear(cmd_tbl_t *cmdtp, int flag, int argc,
 	return report_return_code(tpm2_clear(handle, pw, pw_sz));
 }
 
+static int do_tpm2_pcr_extend(cmd_tbl_t *cmdtp, int flag, int argc,
+			      char * const argv[])
+{
+	u32 index = simple_strtoul(argv[1], NULL, 0);
+	void *digest = (void *)simple_strtoul(argv[2], NULL, 0);
+
+	if (argc != 3)
+		return CMD_RET_USAGE;
+
+	return report_return_code(tpm2_pcr_extend(index, digest));
+}
+
 static cmd_tbl_t tpm2_commands[] = {
 	U_BOOT_CMD_MKENT(info, 0, 1, do_tpm_info, "", ""),
 	U_BOOT_CMD_MKENT(init, 0, 1, do_tpm_init, "", ""),
 	U_BOOT_CMD_MKENT(startup, 0, 1, do_tpm2_startup, "", ""),
 	U_BOOT_CMD_MKENT(self_test, 0, 1, do_tpm2_self_test, "", ""),
 	U_BOOT_CMD_MKENT(clear, 0, 1, do_tpm2_clear, "", ""),
+	U_BOOT_CMD_MKENT(pcr_extend, 0, 1, do_tpm2_pcr_extend, "", ""),
 };
 
 cmd_tbl_t *get_tpm_commands(unsigned int *size)
@@ -111,4 +124,8 @@ U_BOOT_CMD(tpm, CONFIG_SYS_MAXARGS, 1, do_tpm, "Issue a TPMv2.x command",
 "    <hierarchy> is one of:\n"
 "        * TPM2_RH_LOCKOUT\n"
 "        * TPM2_RH_PLATFORM\n"
+"pcr_extend <pcr> <digest_addr>\n"
+"    Extend PCR #<pcr> with digest at <digest_addr>.\n"
+"    <pcr>: index of the PCR\n"
+"    <digest_addr>: address of a 32-byte SHA256 digest\n"
 );
diff --git a/include/tpm-v2.h b/include/tpm-v2.h
index 3aac01b2d0..94c1df77b7 100644
--- a/include/tpm-v2.h
+++ b/include/tpm-v2.h
@@ -154,4 +154,14 @@ u32 tpm2_self_test(enum tpm2_yes_no full_test);
  */
 u32 tpm2_clear(u32 handle, const char *pw, const ssize_t pw_sz);
 
+/**
+ * Issue a TPM2_PCR_Extend command.
+ *
+ * @param index		Index of the PCR
+ * @param digest	Value representing the event to be recorded
+ *
+ * @return return code of the operation
+ */
+u32 tpm2_pcr_extend(u32 index, const uint8_t *digest);
+
 #endif /* __TPM_V2_H */
diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
index e3bfec5082..2696f8145d 100644
--- a/lib/tpm-v2.c
+++ b/lib/tpm-v2.c
@@ -77,3 +77,41 @@ u32 tpm2_clear(u32 handle, const char *pw, const ssize_t pw_sz)
 
 	return tpm_sendrecv_command(command_v2, NULL, NULL);
 }
+
+u32 tpm2_pcr_extend(u32 index, const uint8_t *digest)
+{
+	u8 command_v2[COMMAND_BUFFER_SIZE] = {
+		tpm_u16(TPM2_ST_SESSIONS),	/* TAG */
+		tpm_u32(33 + TPM2_DIGEST_LEN),	/* Length */
+		tpm_u32(TPM2_CC_PCR_EXTEND),	/* Command code */
+
+		/* HANDLE */
+		tpm_u32(index),			/* Handle (PCR Index) */
+
+		/* AUTH_SESSION */
+		tpm_u32(9),			/* Authorization size */
+		tpm_u32(TPM2_RS_PW),		/* Session handle */
+		tpm_u16(0),			/* Size of <nonce> */
+						/* <nonce> (if any) */
+		0,				/* Attributes: Cont/Excl/Rst */
+		tpm_u16(0),			/* Size of <hmac/password> */
+						/* <hmac/password> (if any) */
+		tpm_u32(1),			/* Count (number of hashes) */
+		tpm_u16(TPM2_ALG_SHA256),	/* Algorithm of the hash */
+		/* STRING(digest)		   Digest */
+	};
+	unsigned int offset = 33;
+	int ret;
+
+	/*
+	 * Fill the command structure starting from the first buffer:
+	 *     - the digest
+	 */
+	ret = pack_byte_string(command_v2, sizeof(command_v2), "s",
+			       offset, digest, TPM2_DIGEST_LEN);
+	offset += TPM2_DIGEST_LEN;
+	if (ret)
+		return TPM_LIB_ERROR;
+
+	return tpm_sendrecv_command(command_v2,	NULL, NULL);
+}
-- 
2.14.1