linux-kernel - [PATCH v2 5/5] tpm-buf: Remove tpm_buf_append

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Message-ID: <20251209100529.1700779-6-jarkko@kernel.org>
Date: Tue,  9 Dec 2025 12:05:28 +0200
From: Jarkko Sakkinen <jarkko@...nel.org>
To: linux-integrity@...r.kernel.org
Cc: Jarkko Sakkinen <jarkko@...nel.org>,
	Peter Huewe <peterhuewe@....de>,
	Jason Gunthorpe <jgg@...pe.ca>,
	linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v2 5/5] tpm-buf: Remove tpm_buf_append_handle

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>
v2:
- Streamline the code change and remove dead code.
---
 drivers/char/tpm/tpm-buf.c       | 25 -------------------------
 drivers/char/tpm/tpm2-cmd.c      |  6 ++----
 drivers/char/tpm/tpm2-sessions.c | 14 ++------------
 include/linux/tpm.h              |  2 --
 4 files changed, 4 insertions(+), 43 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..dbcd46c5e09d 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);
 	}
 
@@ -281,10 +281,8 @@ 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;
 			head = (struct tpm_header *)buf->data;
-			if (tpm_buf_length(buf) == offset)
-				head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
+			head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
 		}
 		tpm_buf_append_u16(buf, num_bytes);
 
diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
index 62a200ae72d7..f2b8ca893e15 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;
 	}
 
@@ -288,17 +288,7 @@ EXPORT_SYMBOL_GPL(tpm_buf_append_name);
 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;
-	u32 len = 9 + passphrase_len;
-
-	if (tpm_buf_length(buf) != offset) {
-		/* not the first session so update the existing length */
-		len += get_unaligned_be32(&buf->data[offset]);
-		put_unaligned_be32(len, &buf->data[offset]);
-	} else {
-		tpm_buf_append_u32(buf, len);
-	}
+	tpm_buf_append_u32(buf, 9 + passphrase_len);
 	/* auth handle */
 	tpm_buf_append_u32(buf, TPM2_RS_PW);
 	/* nonce */
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 9f684fc7ae04..e68995df8796 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -395,7 +395,6 @@ enum tpm_buf_flags {
  */
 struct tpm_buf {
 	u8 flags;
-	u8 handles;
 	u16 length;
 	u16 capacity;
 	u8 data[];
@@ -441,7 +440,6 @@ 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.
-- 
2.52.0