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

Jarkko Sakkinen
2015-10-30T11:35:45Z

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@linux.intel.com>
---
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