From 11189d6828ba4aa77916fdf4fcaebc304b349b51 Mon Sep 17 00:00:00 2001 From: James Bottomley Date: Mon, 29 Apr 2024 16:27:59 -0400 Subject: tpm: add buffer function to point to returned parameters Replace all instances of &buf.data[TPM_HEADER_SIZE] with a new function tpm_buf_parameters() because encryption sessions change where the return parameters are located in the buffer since if a return session is present they're 4 bytes beyond the header with those 4 bytes giving the parameter length. If there is no return session, then they're in the usual place immediately after the header. Signed-off-by: James Bottomley Reviewed-by: Stefan Berger Reviewed-by: Jarkko Sakkinen Tested-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen --- drivers/char/tpm/tpm-buf.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) (limited to 'drivers') diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c index cc14fa3fd8c2..6e4595cc98bc 100644 --- a/drivers/char/tpm/tpm-buf.c +++ b/drivers/char/tpm/tpm-buf.c @@ -221,3 +221,31 @@ u32 tpm_buf_read_u32(struct tpm_buf *buf, off_t *offset) return be32_to_cpu(value); } EXPORT_SYMBOL_GPL(tpm_buf_read_u32); + +static u16 tpm_buf_tag(struct tpm_buf *buf) +{ + struct tpm_header *head = (struct tpm_header *)buf->data; + + return be16_to_cpu(head->tag); +} + +/** + * tpm_buf_parameters - return the TPM response parameters area of the tpm_buf + * @buf: tpm_buf to use + * + * Where the parameters are located depends on the tag of a TPM + * command (it's immediately after the header for TPM_ST_NO_SESSIONS + * or 4 bytes after for TPM_ST_SESSIONS). Evaluate this and return a + * pointer to the first byte of the parameters area. + * + * @return: pointer to parameters area + */ +u8 *tpm_buf_parameters(struct tpm_buf *buf) +{ + int offset = TPM_HEADER_SIZE; + + if (tpm_buf_tag(buf) == TPM2_ST_SESSIONS) + offset += 4; + + return &buf->data[offset]; +} -- cgit v1.2.3