[PATCH 06/17] tpm: Use TPM2_NV_ReadPublic to read NV index names

[Matthew Garrett <matthewg@nvidia.com>]

tpm2_read_public() is used by tpm_buf_append_name() to find the name of
a handle for HMAC session calculations. It treats NV indices as needing
a lookup, but sends TPM2_ReadPublic, which only accepts objects, so the
lookup fails for any NV index.

Send TPM2_NV_ReadPublic for NV indices instead. Its response has the
same layout of a public area followed by the name, so the existing
parsing works unchanged.

Signed-off-by: Matthew Garrett <matthewg@nvidia.com>
---
 drivers/char/tpm/tpm2-sessions.c | 11 +++++++++--
 include/linux/tpm_command.h      |  1 +
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
index badc9bec9caa..e5ef30238fbe 100644
--- a/drivers/char/tpm/tpm2-sessions.c
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -225,15 +225,22 @@ static int tpm2_read_public(struct tpm_chip *chip, u32 handle, void *name)
 	if (!buf)
 		return -ENOMEM;
 
+	/*
+	 * NV indices have their own command, whose response has the same
+	 * layout: a public area followed by the name.
+	 */
 	tpm_buf_init(buf, TPM_BUFSIZE);
-	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_READ_PUBLIC);
+	if (mso == TPM2_MSO_NVRAM)
+		tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_NV_READ_PUBLIC);
+	else
+		tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_READ_PUBLIC);
 	tpm_buf_append_u32(buf, handle);
 
 	rc = tpm_transmit_cmd(chip, buf, 0, "TPM2_ReadPublic");
 	if (rc)
 		return tpm_ret_to_err(rc);
 
-	/* Skip TPMT_PUBLIC: */
+	/* Skip TPMT_PUBLIC or TPMS_NV_PUBLIC: */
 	offset += tpm_buf_read_u16(buf, &offset);
 
 	/*
diff --git a/include/linux/tpm_command.h b/include/linux/tpm_command.h
index 486493efa759..9c393f98bac2 100644
--- a/include/linux/tpm_command.h
+++ b/include/linux/tpm_command.h
@@ -241,6 +241,7 @@ enum tpm2_command_codes {
 	TPM2_CC_CONTEXT_LOAD		= 0x0161,
 	TPM2_CC_CONTEXT_SAVE		= 0x0162,
 	TPM2_CC_FLUSH_CONTEXT		= 0x0165,
+	TPM2_CC_NV_READ_PUBLIC		= 0x0169,
 	TPM2_CC_READ_PUBLIC		= 0x0173,
 	TPM2_CC_START_AUTH_SESS		= 0x0176,
 	TPM2_CC_VERIFY_SIGNATURE	= 0x0177,
-- 
2.43.0