[v6] Streamline TPM2 HMAC sessions

[PATCH v6 05/11] tpm2-sessions: Remove AUTH_MAX_NAMES

Posted by Jarkko Sakkinen 1 month, 3 weeks ago

In all of the call sites only one session is ever append. Thus, reduce
AUTH_MAX_NAMES, which leads into removing constant completely.

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 drivers/char/tpm/tpm2-sessions.c | 31 +++++++++++--------------------
 1 file changed, 11 insertions(+), 20 deletions(-)

diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
index 3bc3c31cf512..37570dc088cf 100644
--- a/drivers/char/tpm/tpm2-sessions.c
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -72,9 +72,6 @@
 #include <crypto/sha2.h>
 #include <crypto/utils.h>
 
-/* maximum number of names the TPM must remember for authorization */
-#define AUTH_MAX_NAMES	3
-
 #define AES_KEY_BYTES	AES_KEYSIZE_128
 #define AES_KEY_BITS	(AES_KEY_BYTES*8)
 
@@ -136,8 +133,8 @@ struct tpm2_auth {
 	 * handle, but they are part of the session by name, which
 	 * we must compute and remember
 	 */
-	u8 name[AUTH_MAX_NAMES][TPM2_MAX_NAME_SIZE];
-	u16 name_size_tbl[AUTH_MAX_NAMES];
+	u8 name[TPM2_MAX_NAME_SIZE];
+	u16 name_size;
 };
 
 #ifdef CONFIG_TCG_TPM2_HMAC
@@ -261,11 +258,14 @@ EXPORT_SYMBOL_GPL(tpm2_read_public);
 int tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
 			u32 handle, u8 *name, u16 name_size)
 {
-#ifdef CONFIG_TCG_TPM2_HMAC
 	struct tpm2_auth *auth;
-	int slot;
 	int ret;
-#endif
+
+	if (tpm_buf_length(buf) != TPM_HEADER_SIZE) {
+		dev_err(&chip->dev, "too many handles\n");
+		ret = -EIO;
+		goto err;
+	}
 
 	if (!tpm2_chip_auth(chip)) {
 		tpm_buf_append_handle(chip, buf, handle);
@@ -273,12 +273,6 @@ int tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
 	}
 
 #ifdef CONFIG_TCG_TPM2_HMAC
-	slot = (tpm_buf_length(buf) - TPM_HEADER_SIZE) / 4;
-	if (slot >= AUTH_MAX_NAMES) {
-		dev_err(&chip->dev, "too many handles\n");
-		ret = -EIO;
-		goto err;
-	}
 	auth = chip->auth;
 	if (auth->session != tpm_buf_length(buf)) {
 		dev_err(&chip->dev, "session state malformed");
@@ -287,16 +281,14 @@ int tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
 	}
 	tpm_buf_append_u32(buf, handle);
 	auth->session += 4;
-	memcpy(auth->name[slot], name, name_size);
-	auth->name_size_tbl[slot] = name_size;
+	memcpy(auth->name, name, name_size);
+	auth->name_size = name_size;
 #endif
 	return 0;
 
-#ifdef CONFIG_TCG_TPM2_HMAC
 err:
 	tpm2_end_auth_session(chip);
 	return ret;
-#endif
 }
 EXPORT_SYMBOL_GPL(tpm_buf_append_name);
 
@@ -665,8 +657,7 @@ int tpm_buf_fill_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf)
 	/* ordinal is already BE */
 	sha256_update(&sctx, (u8 *)&head->ordinal, sizeof(head->ordinal));
 	/* add the handle names */
-	for (i = 0; i < handles; i++)
-		sha256_update(&sctx, auth->name[i], auth->name_size_tbl[i]);
+	sha256_update(&sctx, auth->name, auth->name_size);
 	if (offset_s != tpm_buf_length(buf))
 		sha256_update(&sctx, &buf->data[offset_s],
 			      tpm_buf_length(buf) - offset_s);
-- 
2.39.5

Re: [PATCH v6 05/11] tpm2-sessions: Remove AUTH_MAX_NAMES

Posted by ross.philipson@oracle.com 3 weeks, 5 days ago

On 12/14/25 7:38 AM, Jarkko Sakkinen wrote:
> In all of the call sites only one session is ever append. Thus, reduce
> AUTH_MAX_NAMES, which leads into removing constant completely.
> 
> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
> ---
>   drivers/char/tpm/tpm2-sessions.c | 31 +++++++++++--------------------
>   1 file changed, 11 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
> index 3bc3c31cf512..37570dc088cf 100644
> --- a/drivers/char/tpm/tpm2-sessions.c
> +++ b/drivers/char/tpm/tpm2-sessions.c
> @@ -72,9 +72,6 @@
>   #include <crypto/sha2.h>
>   #include <crypto/utils.h>
>   
> -/* maximum number of names the TPM must remember for authorization */
> -#define AUTH_MAX_NAMES	3
> -
>   #define AES_KEY_BYTES	AES_KEYSIZE_128
>   #define AES_KEY_BITS	(AES_KEY_BYTES*8)
>   
> @@ -136,8 +133,8 @@ struct tpm2_auth {
>   	 * handle, but they are part of the session by name, which
>   	 * we must compute and remember
>   	 */
> -	u8 name[AUTH_MAX_NAMES][TPM2_MAX_NAME_SIZE];
> -	u16 name_size_tbl[AUTH_MAX_NAMES];
> +	u8 name[TPM2_MAX_NAME_SIZE];
> +	u16 name_size;
>   };
>   
>   #ifdef CONFIG_TCG_TPM2_HMAC
> @@ -261,11 +258,14 @@ EXPORT_SYMBOL_GPL(tpm2_read_public);
>   int tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
>   			u32 handle, u8 *name, u16 name_size)
>   {
> -#ifdef CONFIG_TCG_TPM2_HMAC

Removing CONFIG_TCG_TPM2_HMAC here causes a warning during compile since 
the auth variable is only used in the CONFIG_TCG_TPM2_HMAC block below.

Ross

>   	struct tpm2_auth *auth;
> -	int slot;
>   	int ret;
> -#endif
> +
> +	if (tpm_buf_length(buf) != TPM_HEADER_SIZE) {
> +		dev_err(&chip->dev, "too many handles\n");
> +		ret = -EIO;
> +		goto err;
> +	}
>   
>   	if (!tpm2_chip_auth(chip)) {
>   		tpm_buf_append_handle(chip, buf, handle);
> @@ -273,12 +273,6 @@ int tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
>   	}
>   
>   #ifdef CONFIG_TCG_TPM2_HMAC
> -	slot = (tpm_buf_length(buf) - TPM_HEADER_SIZE) / 4;
> -	if (slot >= AUTH_MAX_NAMES) {
> -		dev_err(&chip->dev, "too many handles\n");
> -		ret = -EIO;
> -		goto err;
> -	}
>   	auth = chip->auth;
>   	if (auth->session != tpm_buf_length(buf)) {
>   		dev_err(&chip->dev, "session state malformed");
> @@ -287,16 +281,14 @@ int tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
>   	}
>   	tpm_buf_append_u32(buf, handle);
>   	auth->session += 4;
> -	memcpy(auth->name[slot], name, name_size);
> -	auth->name_size_tbl[slot] = name_size;
> +	memcpy(auth->name, name, name_size);
> +	auth->name_size = name_size;
>   #endif
>   	return 0;
>   
> -#ifdef CONFIG_TCG_TPM2_HMAC
>   err:
>   	tpm2_end_auth_session(chip);
>   	return ret;
> -#endif
>   }
>   EXPORT_SYMBOL_GPL(tpm_buf_append_name);
>   
> @@ -665,8 +657,7 @@ int tpm_buf_fill_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf)
>   	/* ordinal is already BE */
>   	sha256_update(&sctx, (u8 *)&head->ordinal, sizeof(head->ordinal));
>   	/* add the handle names */
> -	for (i = 0; i < handles; i++)
> -		sha256_update(&sctx, auth->name[i], auth->name_size_tbl[i]);
> +	sha256_update(&sctx, auth->name, auth->name_size);
>   	if (offset_s != tpm_buf_length(buf))
>   		sha256_update(&sctx, &buf->data[offset_s],
>   			      tpm_buf_length(buf) - offset_s);

Re: [PATCH v6 05/11] tpm2-sessions: Remove AUTH_MAX_NAMES

Posted by Jarkko Sakkinen 3 weeks, 3 days ago

On Mon, Jan 12, 2026 at 04:22:24PM -0800, ross.philipson@oracle.com wrote:
> On 12/14/25 7:38 AM, Jarkko Sakkinen wrote:
> > In all of the call sites only one session is ever append. Thus, reduce
> > AUTH_MAX_NAMES, which leads into removing constant completely.
> > 
> > Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
> > ---
> >   drivers/char/tpm/tpm2-sessions.c | 31 +++++++++++--------------------
> >   1 file changed, 11 insertions(+), 20 deletions(-)
> > 
> > diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
> > index 3bc3c31cf512..37570dc088cf 100644
> > --- a/drivers/char/tpm/tpm2-sessions.c
> > +++ b/drivers/char/tpm/tpm2-sessions.c
> > @@ -72,9 +72,6 @@
> >   #include <crypto/sha2.h>
> >   #include <crypto/utils.h>
> > -/* maximum number of names the TPM must remember for authorization */
> > -#define AUTH_MAX_NAMES	3
> > -
> >   #define AES_KEY_BYTES	AES_KEYSIZE_128
> >   #define AES_KEY_BITS	(AES_KEY_BYTES*8)
> > @@ -136,8 +133,8 @@ struct tpm2_auth {
> >   	 * handle, but they are part of the session by name, which
> >   	 * we must compute and remember
> >   	 */
> > -	u8 name[AUTH_MAX_NAMES][TPM2_MAX_NAME_SIZE];
> > -	u16 name_size_tbl[AUTH_MAX_NAMES];
> > +	u8 name[TPM2_MAX_NAME_SIZE];
> > +	u16 name_size;
> >   };
> >   #ifdef CONFIG_TCG_TPM2_HMAC
> > @@ -261,11 +258,14 @@ EXPORT_SYMBOL_GPL(tpm2_read_public);
> >   int tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
> >   			u32 handle, u8 *name, u16 name_size)
> >   {
> > -#ifdef CONFIG_TCG_TPM2_HMAC
> 
> Removing CONFIG_TCG_TPM2_HMAC here causes a warning during compile since the
> auth variable is only used in the CONFIG_TCG_TPM2_HMAC block below.

Thanks for the remark, I'll look into this.

I should have next week bandwidth to look into your patch set too (still
rebooting from the holidays)

> 
> Ross
> 
> >   	struct tpm2_auth *auth;
> > -	int slot;
> >   	int ret;
> > -#endif
> > +
> > +	if (tpm_buf_length(buf) != TPM_HEADER_SIZE) {
> > +		dev_err(&chip->dev, "too many handles\n");
> > +		ret = -EIO;
> > +		goto err;
> > +	}
> >   	if (!tpm2_chip_auth(chip)) {
> >   		tpm_buf_append_handle(chip, buf, handle);
> > @@ -273,12 +273,6 @@ int tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
> >   	}
> >   #ifdef CONFIG_TCG_TPM2_HMAC
> > -	slot = (tpm_buf_length(buf) - TPM_HEADER_SIZE) / 4;
> > -	if (slot >= AUTH_MAX_NAMES) {
> > -		dev_err(&chip->dev, "too many handles\n");
> > -		ret = -EIO;
> > -		goto err;
> > -	}
> >   	auth = chip->auth;
> >   	if (auth->session != tpm_buf_length(buf)) {
> >   		dev_err(&chip->dev, "session state malformed");
> > @@ -287,16 +281,14 @@ int tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
> >   	}
> >   	tpm_buf_append_u32(buf, handle);
> >   	auth->session += 4;
> > -	memcpy(auth->name[slot], name, name_size);
> > -	auth->name_size_tbl[slot] = name_size;
> > +	memcpy(auth->name, name, name_size);
> > +	auth->name_size = name_size;
> >   #endif
> >   	return 0;
> > -#ifdef CONFIG_TCG_TPM2_HMAC
> >   err:
> >   	tpm2_end_auth_session(chip);
> >   	return ret;
> > -#endif
> >   }
> >   EXPORT_SYMBOL_GPL(tpm_buf_append_name);
> > @@ -665,8 +657,7 @@ int tpm_buf_fill_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf)
> >   	/* ordinal is already BE */
> >   	sha256_update(&sctx, (u8 *)&head->ordinal, sizeof(head->ordinal));
> >   	/* add the handle names */
> > -	for (i = 0; i < handles; i++)
> > -		sha256_update(&sctx, auth->name[i], auth->name_size_tbl[i]);
> > +	sha256_update(&sctx, auth->name, auth->name_size);
> >   	if (offset_s != tpm_buf_length(buf))
> >   		sha256_update(&sctx, &buf->data[offset_s],
> >   			      tpm_buf_length(buf) - offset_s);
> 

BR, Jarkko