[PATCH RFC] tpm: seal with a policy

[Jarkko Sakkinen]

Support for sealing with a policy.

Two new options for trusted keys:

* 'policydigest=': provide a policydigest for the seal operation.
* 'policyhandle=': provide handle for a policy session for unsealing.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
---
 drivers/char/tpm/Kconfig    |  1 +
 drivers/char/tpm/tpm2-cmd.c | 20 +++++++++++++++++---
 include/keys/trusted-type.h |  3 +++
 security/keys/trusted.c     | 26 ++++++++++++++++++++++++--
 4 files changed, 45 insertions(+), 5 deletions(-)

diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
index 3b84a8b..bd86261 100644
--- a/drivers/char/tpm/Kconfig
+++ b/drivers/char/tpm/Kconfig
@@ -6,6 +6,7 @@ menuconfig TCG_TPM
 	tristate "TPM Hardware Support"
 	depends on HAS_IOMEM
 	select SECURITYFS
+	select CRYPTO_HASH_INFO
 	---help---
 	  If you have a TPM security chip in your system, which
 	  implements the Trusted Computing Group's specification,
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index b08a0b4..6f567c3 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -463,6 +463,9 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 			return -EINVAL;
 	}
 
+	if (options->policydigest_len > hash_digest_size[options->hash])
+		return -EINVAL;
+
 	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
 	if (rc)
 		return rc;
@@ -488,8 +491,17 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 
 	tpm_buf_append_u16(&buf, TPM2_ALG_KEYEDHASH);
 	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 */
+
+	if (options->policydigest_len) {
+		tpm_buf_append_u32(&buf, 0);
+		tpm_buf_append_u16(&buf, options->policydigest_len);
+		tpm_buf_append(&buf, options->policydigest,
+			       options->policydigest_len);
+	} else {
+		tpm_buf_append_u32(&buf, TPM2_ATTR_USER_WITH_AUTH);
+		tpm_buf_append_u16(&buf, 0);
+	}
+
 	tpm_buf_append_u16(&buf, TPM2_ALG_NULL);
 	tpm_buf_append_u16(&buf, 0);
 
@@ -617,7 +629,9 @@ static int tpm2_unseal(struct tpm_chip *chip,
 		return rc;
 
 	tpm_buf_append_u32(&buf, blob_handle);
-	tpm2_buf_append_auth(&buf, TPM2_RS_PW,
+	tpm2_buf_append_auth(&buf,
+			     options->policyhandle ?
+			     options->policyhandle : TPM2_RS_PW,
 			     NULL /* nonce */, 0,
 			     0 /* session_attributes */,
 			     options->blobauth /* hmac */,
diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h
index a6a1008..e4beeca 100644
--- a/include/keys/trusted-type.h
+++ b/include/keys/trusted-type.h
@@ -37,6 +37,9 @@ struct trusted_key_options {
 	unsigned char pcrinfo[MAX_PCRINFO_SIZE];
 	int pcrlock;
 	uint32_t hash;
+	uint32_t policydigest_len;
+	unsigned char *policydigest;
+	uint32_t policyhandle;
 };
 
 extern struct key_type key_type_trusted;
diff --git a/security/keys/trusted.c b/security/keys/trusted.c
index 7a87bcd..ea043ff 100644
--- a/security/keys/trusted.c
+++ b/security/keys/trusted.c
@@ -713,6 +713,8 @@ enum {
 	Opt_keyhandle, Opt_keyauth, Opt_blobauth,
 	Opt_pcrinfo, Opt_pcrlock, Opt_migratable,
 	Opt_hash,
+	Opt_policydigest,
+	Opt_policyhandle,
 };
 
 static const match_table_t key_tokens = {
@@ -726,6 +728,8 @@ static const match_table_t key_tokens = {
 	{Opt_pcrlock, "pcrlock=%s"},
 	{Opt_migratable, "migratable=%s"},
 	{Opt_hash, "hash=%s"},
+	{Opt_policydigest, "policydigest=%s"},
+	{Opt_policyhandle, "policyhandle=%s"},
 	{Opt_err, NULL}
 };
 
@@ -804,6 +808,17 @@ static int getoptions(char *c, struct trusted_key_payload *pay,
 			if (i == HASH_ALGO__LAST ||
 			    (!res && i != HASH_ALGO_SHA1))
 				return -EINVAL;
+		case Opt_policydigest:
+			opt->policydigest_len = strlen(args[0].from);
+			opt->policydigest = kstrdup(args[0].from, GFP_KERNEL);
+			if (!opt->policydigest)
+				return -ENOMEM;
+			break;
+		case Opt_policyhandle:
+			res = kstrtoul(args[0].from, 16, &handle);
+			if (res < 0)
+				return -EINVAL;
+			opt->policyhandle = handle;
 			break;
 		default:
 			return -EINVAL;
@@ -897,6 +912,13 @@ static struct trusted_key_options *trusted_options_alloc(void)
 	return options;
 }
 
+static void trusted_options_free(struct trusted_key_options *options)
+{
+	if (options->policydigest)
+		kfree(options->policydigest);
+	kfree(options);
+}
+
 static struct trusted_key_payload *trusted_payload_alloc(struct key *key)
 {
 	struct trusted_key_payload *p = NULL;
@@ -1003,7 +1025,7 @@ static int trusted_instantiate(struct key *key,
 		ret = pcrlock(options->pcrlock);
 out:
 	kfree(datablob);
-	kfree(options);
+	trusted_options_free(options);
 	if (!ret)
 		rcu_assign_keypointer(key, payload);
 	else
@@ -1091,7 +1113,7 @@ static int trusted_update(struct key *key, struct key_preparsed_payload *prep)
 	call_rcu(&p->rcu, trusted_rcu_free);
 out:
 	kfree(datablob);
-	kfree(new_o);
+	trusted_options_free(new_o);
 	return ret;
 }
 
-- 
2.5.0

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