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Message-ID: <aTfVLqMkP43HWR5T@kernel.org>
Date: Tue, 9 Dec 2025 09:52:14 +0200
From: Jarkko Sakkinen <jarkko@...nel.org>
To: linux-integrity@...r.kernel.org
Cc: Peter Huewe <peterhuewe@....de>, Jason Gunthorpe <jgg@...pe.ca>,
James Bottomley <James.Bottomley@...senpartnership.com>,
Mimi Zohar <zohar@...ux.ibm.com>,
David Howells <dhowells@...hat.com>,
Paul Moore <paul@...l-moore.com>, James Morris <jmorris@...ei.org>,
"Serge E. Hallyn" <serge@...lyn.com>,
open list <linux-kernel@...r.kernel.org>,
"open list:KEYS-TRUSTED" <keyrings@...r.kernel.org>,
"open list:SECURITY SUBSYSTEM" <linux-security-module@...r.kernel.org>
Subject: Re: [PATCH 4/4] tpm-buf: Remove tpm_buf_append_handle
On Tue, Dec 09, 2025 at 09:39:02AM +0200, Jarkko Sakkinen wrote:
> Since the number of handles is fixed to a single handle, eliminate all uses
> of buf->handles and deduce values during compile-time.
>
> Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
> ---
> drivers/char/tpm/tpm-buf.c | 25 -----------------------
> drivers/char/tpm/tpm2-cmd.c | 4 ++--
> drivers/char/tpm/tpm2-sessions.c | 4 ++--
> include/linux/tpm.h | 1 -
> security/keys/trusted-keys/trusted_tpm2.c | 2 +-
> 5 files changed, 5 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
> index 73be8a87b472..752c69b8a4f5 100644
> --- a/drivers/char/tpm/tpm-buf.c
> +++ b/drivers/char/tpm/tpm-buf.c
> @@ -40,7 +40,6 @@ static void __tpm_buf_reset(struct tpm_buf *buf, u16 buf_size, u16 tag, u32 ordi
> buf->flags = 0;
> buf->length = sizeof(*head);
> buf->capacity = buf_size - sizeof(*buf);
> - buf->handles = 0;
> head->tag = cpu_to_be16(tag);
> head->length = cpu_to_be32(sizeof(*head));
> head->ordinal = cpu_to_be32(ordinal);
> @@ -56,7 +55,6 @@ static void __tpm_buf_reset_sized(struct tpm_buf *buf, u16 buf_size)
> buf->flags = TPM_BUF_TPM2B;
> buf->length = 2;
> buf->capacity = buf_size - sizeof(*buf);
> - buf->handles = 0;
> buf->data[0] = 0;
> buf->data[1] = 0;
> }
> @@ -177,29 +175,6 @@ void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value)
> }
> EXPORT_SYMBOL_GPL(tpm_buf_append_u32);
>
> -/**
> - * tpm_buf_append_handle() - Add a handle
> - * @buf: &tpm_buf instance
> - * @handle: a TPM object handle
> - *
> - * Add a handle to the buffer, and increase the count tracking the number of
> - * handles in the command buffer. Works only for command buffers.
> - */
> -void tpm_buf_append_handle(struct tpm_buf *buf, u32 handle)
> -{
> - if (buf->flags & TPM_BUF_INVALID)
> - return;
> -
> - if (buf->flags & TPM_BUF_TPM2B) {
> - WARN(1, "tpm-buf: invalid type: TPM2B\n");
> - buf->flags |= TPM_BUF_INVALID;
> - return;
> - }
> -
> - tpm_buf_append_u32(buf, handle);
> - buf->handles++;
> -}
> -
> /**
> * tpm_buf_read() - Read from a TPM buffer
> * @buf: &tpm_buf instance
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index 5b04e74b6377..d14e249831c7 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -205,7 +205,7 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
> return rc;
> tpm_buf_append_hmac_session(chip, buf, 0, NULL, 0);
> } else {
> - tpm_buf_append_handle(buf, pcr_idx);
> + tpm_buf_append_u32(buf, pcr_idx);
> tpm_buf_append_auth(chip, buf, NULL, 0);
> }
>
> @@ -281,7 +281,7 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
> TPM2_SA_CONTINUE_SESSION,
> NULL, 0);
> } else {
> - offset = buf->handles * 4 + TPM_HEADER_SIZE;
> + offset = TPM_HEADER_SIZE + sizeof(u32);
> head = (struct tpm_header *)buf->data;
> if (tpm_buf_length(buf) == offset)
> head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
> diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
> index 62a200ae72d7..dfd1abe673bc 100644
> --- a/drivers/char/tpm/tpm2-sessions.c
> +++ b/drivers/char/tpm/tpm2-sessions.c
> @@ -261,7 +261,7 @@ int tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
> }
>
> if (!tpm2_chip_auth(chip)) {
> - tpm_buf_append_handle(buf, handle);
> + tpm_buf_append_u32(buf, handle);
> return 0;
> }
>
> @@ -289,7 +289,7 @@ void tpm_buf_append_auth(struct tpm_chip *chip, struct tpm_buf *buf,
> u8 *passphrase, int passphrase_len)
> {
> /* offset tells us where the sessions area begins */
> - int offset = buf->handles * 4 + TPM_HEADER_SIZE;
> + int offset = TPM_HEADER_SIZE + sizeof(u32);
> u32 len = 9 + passphrase_len;
>
> if (tpm_buf_length(buf) != offset) {
> diff --git a/include/linux/tpm.h b/include/linux/tpm.h
> index db716841973f..e20647cc0a0f 100644
> --- a/include/linux/tpm.h
> +++ b/include/linux/tpm.h
> @@ -437,7 +437,6 @@ void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value);
> u8 tpm_buf_read_u8(struct tpm_buf *buf, off_t *offset);
> u16 tpm_buf_read_u16(struct tpm_buf *buf, off_t *offset);
> u32 tpm_buf_read_u32(struct tpm_buf *buf, off_t *offset);
> -void tpm_buf_append_handle(struct tpm_buf *buf, u32 handle);
>
> /*
> * Check if TPM device is in the firmware upgrade mode.
> diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
> index 7756aa839d81..0a07a18da2ed 100644
> --- a/security/keys/trusted-keys/trusted_tpm2.c
> +++ b/security/keys/trusted-keys/trusted_tpm2.c
> @@ -495,7 +495,7 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
> if (tpm2_chip_auth(chip)) {
> tpm_buf_append_hmac_session(chip, buf, TPM2_SA_ENCRYPT, NULL, 0);
> } else {
> - offset = buf->handles * 4 + TPM_HEADER_SIZE;
> + offset = TPM_HEADER_SIZE + sizeof(u32);
Maybe it would be sensible to define:
/*
* Offset of the authorization area of a TPM command with a single
* handle.
*/
#define TPM2_AUTH_OFFSET (TPM_HEADER_SIZE + sizeof(u32))
This would overall clarify how this code works.
> head = (struct tpm_header *)buf->data;
> if (tpm_buf_length(buf) == offset)
> head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
> --
> 2.52.0
>
BR, Jarkko
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