diff mbox series

[v7,2/4] KEYS: Use common tpm_buf for trusted and asymmetric keys

Message ID 1570425935-7435-3-git-send-email-sumit.garg@linaro.org (mailing list archive)
State New, archived
Headers show
Series Create and consolidate trusted keys subsystem | expand

Commit Message

Sumit Garg Oct. 7, 2019, 5:25 a.m. UTC 
Switch to utilize common heap based tpm_buf code for TPM based trusted
and asymmetric keys rather than using stack based tpm1_buf code. Also,
remove tpm1_buf code.

Suggested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
---
 crypto/asymmetric_keys/asym_tpm.c | 107 ++++++++++++++++----------------------
 include/keys/trusted.h            |  37 +------------
 security/keys/trusted.c           |  98 +++++++++++++++-------------------
 3 files changed, 89 insertions(+), 153 deletions(-)

Comments

Jarkko Sakkinen Oct. 11, 2019, 11:47 a.m. UTC | #1 
On Mon, Oct 07, 2019 at 10:55:33AM +0530, Sumit Garg wrote:
> Switch to utilize common heap based tpm_buf code for TPM based trusted
> and asymmetric keys rather than using stack based tpm1_buf code. Also,
> remove tpm1_buf code.
> 
> Suggested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> Signed-off-by: Sumit Garg <sumit.garg@linaro.org>

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

/Jarkko
Jerry Snitselaar Oct. 11, 2019, 10:34 p.m. UTC | #2 
On Mon Oct 07 19, Sumit Garg wrote:
>Switch to utilize common heap based tpm_buf code for TPM based trusted
>and asymmetric keys rather than using stack based tpm1_buf code. Also,
>remove tpm1_buf code.
>
>Suggested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
>Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
>---

Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
diff mbox series

Patch

diff --git a/crypto/asymmetric_keys/asym_tpm.c b/crypto/asymmetric_keys/asym_tpm.c
index b88968d..a2b2a61 100644
--- a/crypto/asymmetric_keys/asym_tpm.c
+++ b/crypto/asymmetric_keys/asym_tpm.c
@@ -21,17 +21,13 @@ 
 #define TPM_ORD_LOADKEY2	65
 #define TPM_ORD_UNBIND		30
 #define TPM_ORD_SIGN		60
-#define TPM_LOADKEY2_SIZE		59
-#define TPM_FLUSHSPECIFIC_SIZE		18
-#define TPM_UNBIND_SIZE			63
-#define TPM_SIGN_SIZE			63
 
 #define TPM_RT_KEY                      0x00000001
 
 /*
  * Load a TPM key from the blob provided by userspace
  */
-static int tpm_loadkey2(struct tpm1_buf *tb,
+static int tpm_loadkey2(struct tpm_buf *tb,
 			uint32_t keyhandle, unsigned char *keyauth,
 			const unsigned char *keyblob, int keybloblen,
 			uint32_t *newhandle)
@@ -68,16 +64,13 @@  static int tpm_loadkey2(struct tpm1_buf *tb,
 		return ret;
 
 	/* build the request buffer */
-	INIT_BUF(tb);
-	store16(tb, TPM_TAG_RQU_AUTH1_COMMAND);
-	store32(tb, TPM_LOADKEY2_SIZE + keybloblen);
-	store32(tb, TPM_ORD_LOADKEY2);
-	store32(tb, keyhandle);
-	storebytes(tb, keyblob, keybloblen);
-	store32(tb, authhandle);
-	storebytes(tb, nonceodd, TPM_NONCE_SIZE);
-	store8(tb, cont);
-	storebytes(tb, authdata, SHA1_DIGEST_SIZE);
+	tpm_buf_reset(tb, TPM_TAG_RQU_AUTH1_COMMAND, TPM_ORD_LOADKEY2);
+	tpm_buf_append_u32(tb, keyhandle);
+	tpm_buf_append(tb, keyblob, keybloblen);
+	tpm_buf_append_u32(tb, authhandle);
+	tpm_buf_append(tb, nonceodd, TPM_NONCE_SIZE);
+	tpm_buf_append_u8(tb, cont);
+	tpm_buf_append(tb, authdata, SHA1_DIGEST_SIZE);
 
 	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
 	if (ret < 0) {
@@ -99,14 +92,11 @@  static int tpm_loadkey2(struct tpm1_buf *tb,
 /*
  * Execute the FlushSpecific TPM command
  */
-static int tpm_flushspecific(struct tpm1_buf *tb, uint32_t handle)
+static int tpm_flushspecific(struct tpm_buf *tb, uint32_t handle)
 {
-	INIT_BUF(tb);
-	store16(tb, TPM_TAG_RQU_COMMAND);
-	store32(tb, TPM_FLUSHSPECIFIC_SIZE);
-	store32(tb, TPM_ORD_FLUSHSPECIFIC);
-	store32(tb, handle);
-	store32(tb, TPM_RT_KEY);
+	tpm_buf_reset(tb, TPM_TAG_RQU_COMMAND, TPM_ORD_FLUSHSPECIFIC);
+	tpm_buf_append_u32(tb, handle);
+	tpm_buf_append_u32(tb, TPM_RT_KEY);
 
 	return trusted_tpm_send(tb->data, MAX_BUF_SIZE);
 }
@@ -115,7 +105,7 @@  static int tpm_flushspecific(struct tpm1_buf *tb, uint32_t handle)
  * Decrypt a blob provided by userspace using a specific key handle.
  * The handle is a well known handle or previously loaded by e.g. LoadKey2
  */
-static int tpm_unbind(struct tpm1_buf *tb,
+static int tpm_unbind(struct tpm_buf *tb,
 			uint32_t keyhandle, unsigned char *keyauth,
 			const unsigned char *blob, uint32_t bloblen,
 			void *out, uint32_t outlen)
@@ -155,17 +145,14 @@  static int tpm_unbind(struct tpm1_buf *tb,
 		return ret;
 
 	/* build the request buffer */
-	INIT_BUF(tb);
-	store16(tb, TPM_TAG_RQU_AUTH1_COMMAND);
-	store32(tb, TPM_UNBIND_SIZE + bloblen);
-	store32(tb, TPM_ORD_UNBIND);
-	store32(tb, keyhandle);
-	store32(tb, bloblen);
-	storebytes(tb, blob, bloblen);
-	store32(tb, authhandle);
-	storebytes(tb, nonceodd, TPM_NONCE_SIZE);
-	store8(tb, cont);
-	storebytes(tb, authdata, SHA1_DIGEST_SIZE);
+	tpm_buf_reset(tb, TPM_TAG_RQU_AUTH1_COMMAND, TPM_ORD_UNBIND);
+	tpm_buf_append_u32(tb, keyhandle);
+	tpm_buf_append_u32(tb, bloblen);
+	tpm_buf_append(tb, blob, bloblen);
+	tpm_buf_append_u32(tb, authhandle);
+	tpm_buf_append(tb, nonceodd, TPM_NONCE_SIZE);
+	tpm_buf_append_u8(tb, cont);
+	tpm_buf_append(tb, authdata, SHA1_DIGEST_SIZE);
 
 	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
 	if (ret < 0) {
@@ -201,7 +188,7 @@  static int tpm_unbind(struct tpm1_buf *tb,
  * up to key_length_in_bytes - 11 and not be limited to size 20 like the
  * TPM_SS_RSASSAPKCS1v15_SHA1 signature scheme.
  */
-static int tpm_sign(struct tpm1_buf *tb,
+static int tpm_sign(struct tpm_buf *tb,
 		    uint32_t keyhandle, unsigned char *keyauth,
 		    const unsigned char *blob, uint32_t bloblen,
 		    void *out, uint32_t outlen)
@@ -241,17 +228,14 @@  static int tpm_sign(struct tpm1_buf *tb,
 		return ret;
 
 	/* build the request buffer */
-	INIT_BUF(tb);
-	store16(tb, TPM_TAG_RQU_AUTH1_COMMAND);
-	store32(tb, TPM_SIGN_SIZE + bloblen);
-	store32(tb, TPM_ORD_SIGN);
-	store32(tb, keyhandle);
-	store32(tb, bloblen);
-	storebytes(tb, blob, bloblen);
-	store32(tb, authhandle);
-	storebytes(tb, nonceodd, TPM_NONCE_SIZE);
-	store8(tb, cont);
-	storebytes(tb, authdata, SHA1_DIGEST_SIZE);
+	tpm_buf_reset(tb, TPM_TAG_RQU_AUTH1_COMMAND, TPM_ORD_SIGN);
+	tpm_buf_append_u32(tb, keyhandle);
+	tpm_buf_append_u32(tb, bloblen);
+	tpm_buf_append(tb, blob, bloblen);
+	tpm_buf_append_u32(tb, authhandle);
+	tpm_buf_append(tb, nonceodd, TPM_NONCE_SIZE);
+	tpm_buf_append_u8(tb, cont);
+	tpm_buf_append(tb, authdata, SHA1_DIGEST_SIZE);
 
 	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
 	if (ret < 0) {
@@ -519,7 +503,7 @@  static int tpm_key_decrypt(struct tpm_key *tk,
 			   struct kernel_pkey_params *params,
 			   const void *in, void *out)
 {
-	struct tpm1_buf *tb;
+	struct tpm_buf tb;
 	uint32_t keyhandle;
 	uint8_t srkauth[SHA1_DIGEST_SIZE];
 	uint8_t keyauth[SHA1_DIGEST_SIZE];
@@ -533,14 +517,14 @@  static int tpm_key_decrypt(struct tpm_key *tk,
 	if (strcmp(params->encoding, "pkcs1"))
 		return -ENOPKG;
 
-	tb = kzalloc(sizeof(*tb), GFP_KERNEL);
-	if (!tb)
-		return -ENOMEM;
+	r = tpm_buf_init(&tb, 0, 0);
+	if (r)
+		return r;
 
 	/* TODO: Handle a non-all zero SRK authorization */
 	memset(srkauth, 0, sizeof(srkauth));
 
-	r = tpm_loadkey2(tb, SRKHANDLE, srkauth,
+	r = tpm_loadkey2(&tb, SRKHANDLE, srkauth,
 				tk->blob, tk->blob_len, &keyhandle);
 	if (r < 0) {
 		pr_devel("loadkey2 failed (%d)\n", r);
@@ -550,16 +534,16 @@  static int tpm_key_decrypt(struct tpm_key *tk,
 	/* TODO: Handle a non-all zero key authorization */
 	memset(keyauth, 0, sizeof(keyauth));
 
-	r = tpm_unbind(tb, keyhandle, keyauth,
+	r = tpm_unbind(&tb, keyhandle, keyauth,
 		       in, params->in_len, out, params->out_len);
 	if (r < 0)
 		pr_devel("tpm_unbind failed (%d)\n", r);
 
-	if (tpm_flushspecific(tb, keyhandle) < 0)
+	if (tpm_flushspecific(&tb, keyhandle) < 0)
 		pr_devel("flushspecific failed (%d)\n", r);
 
 error:
-	kzfree(tb);
+	tpm_buf_destroy(&tb);
 	pr_devel("<==%s() = %d\n", __func__, r);
 	return r;
 }
@@ -643,7 +627,7 @@  static int tpm_key_sign(struct tpm_key *tk,
 			struct kernel_pkey_params *params,
 			const void *in, void *out)
 {
-	struct tpm1_buf *tb;
+	struct tpm_buf tb;
 	uint32_t keyhandle;
 	uint8_t srkauth[SHA1_DIGEST_SIZE];
 	uint8_t keyauth[SHA1_DIGEST_SIZE];
@@ -681,15 +665,14 @@  static int tpm_key_sign(struct tpm_key *tk,
 		goto error_free_asn1_wrapped;
 	}
 
-	r = -ENOMEM;
-	tb = kzalloc(sizeof(*tb), GFP_KERNEL);
-	if (!tb)
+	r = tpm_buf_init(&tb, 0, 0);
+	if (r)
 		goto error_free_asn1_wrapped;
 
 	/* TODO: Handle a non-all zero SRK authorization */
 	memset(srkauth, 0, sizeof(srkauth));
 
-	r = tpm_loadkey2(tb, SRKHANDLE, srkauth,
+	r = tpm_loadkey2(&tb, SRKHANDLE, srkauth,
 			 tk->blob, tk->blob_len, &keyhandle);
 	if (r < 0) {
 		pr_devel("loadkey2 failed (%d)\n", r);
@@ -699,15 +682,15 @@  static int tpm_key_sign(struct tpm_key *tk,
 	/* TODO: Handle a non-all zero key authorization */
 	memset(keyauth, 0, sizeof(keyauth));
 
-	r = tpm_sign(tb, keyhandle, keyauth, in, in_len, out, params->out_len);
+	r = tpm_sign(&tb, keyhandle, keyauth, in, in_len, out, params->out_len);
 	if (r < 0)
 		pr_devel("tpm_sign failed (%d)\n", r);
 
-	if (tpm_flushspecific(tb, keyhandle) < 0)
+	if (tpm_flushspecific(&tb, keyhandle) < 0)
 		pr_devel("flushspecific failed (%d)\n", r);
 
 error_free_tb:
-	kzfree(tb);
+	tpm_buf_destroy(&tb);
 error_free_asn1_wrapped:
 	kfree(asn1_wrapped);
 	pr_devel("<==%s() = %d\n", __func__, r);
diff --git a/include/keys/trusted.h b/include/keys/trusted.h
index 841ae11..29e3e9b 100644
--- a/include/keys/trusted.h
+++ b/include/keys/trusted.h
@@ -5,10 +5,6 @@ 
 /* implementation specific TPM constants */
 #define MAX_BUF_SIZE			1024
 #define TPM_GETRANDOM_SIZE		14
-#define TPM_OSAP_SIZE			36
-#define TPM_OIAP_SIZE			10
-#define TPM_SEAL_SIZE			87
-#define TPM_UNSEAL_SIZE			104
 #define TPM_SIZE_OFFSET			2
 #define TPM_RETURN_OFFSET		6
 #define TPM_DATA_OFFSET			10
@@ -17,13 +13,6 @@ 
 #define LOAD32N(buffer, offset)	(*(uint32_t *)&buffer[offset])
 #define LOAD16(buffer, offset)	(ntohs(*(uint16_t *)&buffer[offset]))
 
-struct tpm1_buf {
-	int len;
-	unsigned char data[MAX_BUF_SIZE];
-};
-
-#define INIT_BUF(tb) (tb->len = 0)
-
 struct osapsess {
 	uint32_t handle;
 	unsigned char secret[SHA1_DIGEST_SIZE];
@@ -46,7 +35,7 @@  int TSS_checkhmac1(unsigned char *buffer,
 			  unsigned int keylen, ...);
 
 int trusted_tpm_send(unsigned char *cmd, size_t buflen);
-int oiap(struct tpm1_buf *tb, uint32_t *handle, unsigned char *nonce);
+int oiap(struct tpm_buf *tb, uint32_t *handle, unsigned char *nonce);
 
 #define TPM_DEBUG 0
 
@@ -109,28 +98,4 @@  static inline void dump_tpm_buf(unsigned char *buf)
 {
 }
 #endif
-
-static inline void store8(struct tpm1_buf *buf, const unsigned char value)
-{
-	buf->data[buf->len++] = value;
-}
-
-static inline void store16(struct tpm1_buf *buf, const uint16_t value)
-{
-	*(uint16_t *) & buf->data[buf->len] = htons(value);
-	buf->len += sizeof value;
-}
-
-static inline void store32(struct tpm1_buf *buf, const uint32_t value)
-{
-	*(uint32_t *) & buf->data[buf->len] = htonl(value);
-	buf->len += sizeof value;
-}
-
-static inline void storebytes(struct tpm1_buf *buf, const unsigned char *in,
-			      const int len)
-{
-	memcpy(buf->data + buf->len, in, len);
-	buf->len += len;
-}
 #endif
diff --git a/security/keys/trusted.c b/security/keys/trusted.c
index 4cfae208..7071011 100644
--- a/security/keys/trusted.c
+++ b/security/keys/trusted.c
@@ -395,7 +395,7 @@  static int pcrlock(const int pcrnum)
 /*
  * Create an object specific authorisation protocol (OSAP) session
  */
-static int osap(struct tpm1_buf *tb, struct osapsess *s,
+static int osap(struct tpm_buf *tb, struct osapsess *s,
 		const unsigned char *key, uint16_t type, uint32_t handle)
 {
 	unsigned char enonce[TPM_NONCE_SIZE];
@@ -406,13 +406,10 @@  static int osap(struct tpm1_buf *tb, struct osapsess *s,
 	if (ret != TPM_NONCE_SIZE)
 		return ret;
 
-	INIT_BUF(tb);
-	store16(tb, TPM_TAG_RQU_COMMAND);
-	store32(tb, TPM_OSAP_SIZE);
-	store32(tb, TPM_ORD_OSAP);
-	store16(tb, type);
-	store32(tb, handle);
-	storebytes(tb, ononce, TPM_NONCE_SIZE);
+	tpm_buf_reset(tb, TPM_TAG_RQU_COMMAND, TPM_ORD_OSAP);
+	tpm_buf_append_u16(tb, type);
+	tpm_buf_append_u32(tb, handle);
+	tpm_buf_append(tb, ononce, TPM_NONCE_SIZE);
 
 	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
 	if (ret < 0)
@@ -430,17 +427,14 @@  static int osap(struct tpm1_buf *tb, struct osapsess *s,
 /*
  * Create an object independent authorisation protocol (oiap) session
  */
-int oiap(struct tpm1_buf *tb, uint32_t *handle, unsigned char *nonce)
+int oiap(struct tpm_buf *tb, uint32_t *handle, unsigned char *nonce)
 {
 	int ret;
 
 	if (!chip)
 		return -ENODEV;
 
-	INIT_BUF(tb);
-	store16(tb, TPM_TAG_RQU_COMMAND);
-	store32(tb, TPM_OIAP_SIZE);
-	store32(tb, TPM_ORD_OIAP);
+	tpm_buf_reset(tb, TPM_TAG_RQU_COMMAND, TPM_ORD_OIAP);
 	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
 	if (ret < 0)
 		return ret;
@@ -464,7 +458,7 @@  struct tpm_digests {
  * Have the TPM seal(encrypt) the trusted key, possibly based on
  * Platform Configuration Registers (PCRs). AUTH1 for sealing key.
  */
-static int tpm_seal(struct tpm1_buf *tb, uint16_t keytype,
+static int tpm_seal(struct tpm_buf *tb, uint16_t keytype,
 		    uint32_t keyhandle, const unsigned char *keyauth,
 		    const unsigned char *data, uint32_t datalen,
 		    unsigned char *blob, uint32_t *bloblen,
@@ -535,20 +529,17 @@  static int tpm_seal(struct tpm1_buf *tb, uint16_t keytype,
 		goto out;
 
 	/* build and send the TPM request packet */
-	INIT_BUF(tb);
-	store16(tb, TPM_TAG_RQU_AUTH1_COMMAND);
-	store32(tb, TPM_SEAL_SIZE + pcrinfosize + datalen);
-	store32(tb, TPM_ORD_SEAL);
-	store32(tb, keyhandle);
-	storebytes(tb, td->encauth, SHA1_DIGEST_SIZE);
-	store32(tb, pcrinfosize);
-	storebytes(tb, pcrinfo, pcrinfosize);
-	store32(tb, datalen);
-	storebytes(tb, data, datalen);
-	store32(tb, sess.handle);
-	storebytes(tb, td->nonceodd, TPM_NONCE_SIZE);
-	store8(tb, cont);
-	storebytes(tb, td->pubauth, SHA1_DIGEST_SIZE);
+	tpm_buf_reset(tb, TPM_TAG_RQU_AUTH1_COMMAND, TPM_ORD_SEAL);
+	tpm_buf_append_u32(tb, keyhandle);
+	tpm_buf_append(tb, td->encauth, SHA1_DIGEST_SIZE);
+	tpm_buf_append_u32(tb, pcrinfosize);
+	tpm_buf_append(tb, pcrinfo, pcrinfosize);
+	tpm_buf_append_u32(tb, datalen);
+	tpm_buf_append(tb, data, datalen);
+	tpm_buf_append_u32(tb, sess.handle);
+	tpm_buf_append(tb, td->nonceodd, TPM_NONCE_SIZE);
+	tpm_buf_append_u8(tb, cont);
+	tpm_buf_append(tb, td->pubauth, SHA1_DIGEST_SIZE);
 
 	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
 	if (ret < 0)
@@ -579,7 +570,7 @@  static int tpm_seal(struct tpm1_buf *tb, uint16_t keytype,
 /*
  * use the AUTH2_COMMAND form of unseal, to authorize both key and blob
  */
-static int tpm_unseal(struct tpm1_buf *tb,
+static int tpm_unseal(struct tpm_buf *tb,
 		      uint32_t keyhandle, const unsigned char *keyauth,
 		      const unsigned char *blob, int bloblen,
 		      const unsigned char *blobauth,
@@ -628,20 +619,17 @@  static int tpm_unseal(struct tpm1_buf *tb,
 		return ret;
 
 	/* build and send TPM request packet */
-	INIT_BUF(tb);
-	store16(tb, TPM_TAG_RQU_AUTH2_COMMAND);
-	store32(tb, TPM_UNSEAL_SIZE + bloblen);
-	store32(tb, TPM_ORD_UNSEAL);
-	store32(tb, keyhandle);
-	storebytes(tb, blob, bloblen);
-	store32(tb, authhandle1);
-	storebytes(tb, nonceodd, TPM_NONCE_SIZE);
-	store8(tb, cont);
-	storebytes(tb, authdata1, SHA1_DIGEST_SIZE);
-	store32(tb, authhandle2);
-	storebytes(tb, nonceodd, TPM_NONCE_SIZE);
-	store8(tb, cont);
-	storebytes(tb, authdata2, SHA1_DIGEST_SIZE);
+	tpm_buf_reset(tb, TPM_TAG_RQU_AUTH2_COMMAND, TPM_ORD_UNSEAL);
+	tpm_buf_append_u32(tb, keyhandle);
+	tpm_buf_append(tb, blob, bloblen);
+	tpm_buf_append_u32(tb, authhandle1);
+	tpm_buf_append(tb, nonceodd, TPM_NONCE_SIZE);
+	tpm_buf_append_u8(tb, cont);
+	tpm_buf_append(tb, authdata1, SHA1_DIGEST_SIZE);
+	tpm_buf_append_u32(tb, authhandle2);
+	tpm_buf_append(tb, nonceodd, TPM_NONCE_SIZE);
+	tpm_buf_append_u8(tb, cont);
+	tpm_buf_append(tb, authdata2, SHA1_DIGEST_SIZE);
 
 	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
 	if (ret < 0) {
@@ -670,23 +658,23 @@  static int tpm_unseal(struct tpm1_buf *tb,
 static int key_seal(struct trusted_key_payload *p,
 		    struct trusted_key_options *o)
 {
-	struct tpm1_buf *tb;
+	struct tpm_buf tb;
 	int ret;
 
-	tb = kzalloc(sizeof *tb, GFP_KERNEL);
-	if (!tb)
-		return -ENOMEM;
+	ret = tpm_buf_init(&tb, 0, 0);
+	if (ret)
+		return ret;
 
 	/* include migratable flag at end of sealed key */
 	p->key[p->key_len] = p->migratable;
 
-	ret = tpm_seal(tb, o->keytype, o->keyhandle, o->keyauth,
+	ret = tpm_seal(&tb, o->keytype, o->keyhandle, o->keyauth,
 		       p->key, p->key_len + 1, p->blob, &p->blob_len,
 		       o->blobauth, o->pcrinfo, o->pcrinfo_len);
 	if (ret < 0)
 		pr_info("trusted_key: srkseal failed (%d)\n", ret);
 
-	kzfree(tb);
+	tpm_buf_destroy(&tb);
 	return ret;
 }
 
@@ -696,14 +684,14 @@  static int key_seal(struct trusted_key_payload *p,
 static int key_unseal(struct trusted_key_payload *p,
 		      struct trusted_key_options *o)
 {
-	struct tpm1_buf *tb;
+	struct tpm_buf tb;
 	int ret;
 
-	tb = kzalloc(sizeof *tb, GFP_KERNEL);
-	if (!tb)
-		return -ENOMEM;
+	ret = tpm_buf_init(&tb, 0, 0);
+	if (ret)
+		return ret;
 
-	ret = tpm_unseal(tb, o->keyhandle, o->keyauth, p->blob, p->blob_len,
+	ret = tpm_unseal(&tb, o->keyhandle, o->keyauth, p->blob, p->blob_len,
 			 o->blobauth, p->key, &p->key_len);
 	if (ret < 0)
 		pr_info("trusted_key: srkunseal failed (%d)\n", ret);
@@ -711,7 +699,7 @@  static int key_unseal(struct trusted_key_payload *p,
 		/* pull migratable flag out of sealed key */
 		p->migratable = p->key[--p->key_len];
 
-	kzfree(tb);
+	tpm_buf_destroy(&tb);
 	return ret;
 }