[PATCH v2 3/3] tpm: choose hash algorithm for sealing when using TPM 2.0

[Jarkko Sakkinen]

Support for the following hash algorithms in TPM 2.0 trusted key
sealing:

* sha1
* sha256
* sha384
* sha512
* sm3-256

The hash algorithm can be selected by using HASH_ALGO_* constants in
include/uapi/linux/hash_info.h.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
---
 drivers/char/tpm/tpm.h      | 10 +++++++---
 drivers/char/tpm/tpm2-cmd.c | 42 +++++++++++++++++++++++++++++++++++++++---
 2 files changed, 46 insertions(+), 6 deletions(-)

diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index a4257a3..cdd49cd 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -83,16 +83,20 @@ enum tpm2_structures {
 };
 
 enum tpm2_return_codes {
-	TPM2_RC_INITIALIZE	= 0x0100,
-	TPM2_RC_TESTING		= 0x090A,
+	TPM2_RC_HASH		= 0x0083, /* RC_FMT1 */
+	TPM2_RC_INITIALIZE	= 0x0100, /* RC_VER1 */
 	TPM2_RC_DISABLED	= 0x0120,
+	TPM2_RC_TESTING		= 0x090A, /* RC_WARN */
 };
 
 enum tpm2_algorithms {
 	TPM2_ALG_SHA1		= 0x0004,
 	TPM2_ALG_KEYEDHASH	= 0x0008,
 	TPM2_ALG_SHA256		= 0x000B,
-	TPM2_ALG_NULL		= 0x0010
+	TPM2_ALG_SHA384		= 0x000C,
+	TPM2_ALG_SHA512		= 0x000D,
+	TPM2_ALG_NULL		= 0x0010,
+	TPM2_ALG_SM3_256	= 0x0012,
 };
 
 enum tpm2_command_codes {
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index bd7039f..bc2564e 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -16,6 +16,7 @@
  */
 
 #include "tpm.h"
+#include <crypto/hash_info.h>
 #include <keys/trusted-type.h>
 
 enum tpm2_object_attributes {
@@ -104,6 +105,21 @@ struct tpm2_cmd {
 	union tpm2_cmd_params	params;
 } __packed;
 
+struct tpm2_hash {
+	unsigned int crypto_id;
+	unsigned int tpm_id;
+};
+
+static struct tpm2_hash tpm2_hash_map[] = {
+	{HASH_ALGO_SHA1, TPM2_ALG_SHA1},
+	{HASH_ALGO_SHA256, TPM2_ALG_SHA256},
+	{HASH_ALGO_SHA384, TPM2_ALG_SHA384},
+	{HASH_ALGO_SHA512, TPM2_ALG_SHA512},
+	{HASH_ALGO_SM3_256, TPM2_ALG_SM3_256},
+};
+
+#define TPM2_HASH_COUNT (sizeof(tpm2_hash_map) / sizeof(tpm2_hash_map[1]))
+
 /*
  * Array with one entry per ordinal defining the maximum amount
  * of time the chip could take to return the result. The values
@@ -429,8 +445,24 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 {
 	unsigned int blob_len;
 	struct tpm_buf buf;
+	u32 hash = TPM2_ALG_SHA256;
+	int i;
 	int rc;
 
+	if (options->hash) {
+		for (i = 0; i < TPM2_HASH_COUNT; i++) {
+			if (options->hash == tpm2_hash_map[i].crypto_id) {
+				hash = tpm2_hash_map[i].tpm_id;
+				dev_dbg(chip->pdev, "%s: hash: %s 0x%08X\n",
+					__func__, hash_algo_name[i], hash);
+				break;
+			}
+		}
+
+		if (i == TPM2_HASH_COUNT)
+			return -EINVAL;
+	}
+
 	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
 	if (rc)
 		return rc;
@@ -454,7 +486,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	tpm_buf_append_u16(&buf, 14);
 
 	tpm_buf_append_u16(&buf, TPM2_ALG_KEYEDHASH);
-	tpm_buf_append_u16(&buf, TPM2_ALG_SHA256);
+	tpm_buf_append_u16(&buf, hash);
 	tpm_buf_append_u32(&buf, TPM2_ATTR_USER_WITH_AUTH);
 	tpm_buf_append_u16(&buf, 0); /* policy digest size */
 	tpm_buf_append_u16(&buf, TPM2_ALG_NULL);
@@ -487,8 +519,12 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 out:
 	tpm_buf_destroy(&buf);
 
-	if (rc > 0)
-		rc = -EPERM;
+	if (rc > 0) {
+		if ((rc & TPM2_RC_HASH) == TPM2_RC_HASH)
+			rc = -EINVAL;
+		else
+			rc = -EPERM;
+	}
 
 	return rc;
 }
-- 
2.5.0

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