linux-kernel - Re: [PATCH v3 2/6] tpm: Store TPM buffer length

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Message-ID: <4gyb46g6makecsv7mq67qdp5hilytpymvdbffz5q64tday5dva@wjg3achi5rrv>
Date:   Mon, 6 Nov 2023 12:36:29 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     Jarkko Sakkinen <jarkko@...nel.org>
Cc:     linux-integrity@...r.kernel.org, keyrings@...r.kernel.org,
        James Bottomley <James.Bottomley@...senpartnership.com>,
        William Roberts <bill.c.roberts@...il.com>,
        Stefan Berger <stefanb@...ux.ibm.com>,
        David Howells <dhowells@...hat.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Peter Huewe <peterhuewe@....de>,
        James Bottomley <jejb@...ux.ibm.com>,
        Paul Moore <paul@...l-moore.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Julien Gomes <julien@...sta.com>,
        Mario Limonciello <mario.limonciello@....com>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:SECURITY SUBSYSTEM" 
        <linux-security-module@...r.kernel.org>
Subject: Re: [PATCH v3 2/6] tpm: Store TPM buffer length

On Tue, Oct 24, 2023 at 04:15:20AM +0300, Jarkko Sakkinen wrote:
> Both TPM commands and sized buffers (TPM2B) have a fixed size header, which
> is followed by the body. Store TPM buffer length to a new field in the
> struct tpm_buf.
> 
> The invariant here is that the length field must always contain the total
> length of the buffer, i.e. the sum header and body length. The value must
> then be mapped to the length representation of the buffer type, and this
> correspondence must be maintained.
> 
> Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
> ---
>  drivers/char/tpm/tpm-buf.c                | 36 ++++++++++++++++-------
>  drivers/char/tpm/tpm-interface.c          | 18 +++++++++---
>  include/linux/tpm.h                       | 10 +++----
>  security/keys/trusted-keys/trusted_tpm1.c |  8 ++---
>  4 files changed, 49 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
> index 88ce1a5402de..8dc6b9db006b 100644
> --- a/drivers/char/tpm/tpm-buf.c
> +++ b/drivers/char/tpm/tpm-buf.c
> @@ -18,6 +18,12 @@ int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal)
>  }
>  EXPORT_SYMBOL_GPL(tpm_buf_init);
>  
> +/**
> + * tpm_buf_reset() - Initialize a TPM command
> + * @buf:	A @tpm_buf

One minor thing I meant to mention, did you intend this to be &tpm_buf like it
is for tpm_buf_append?

Regards,
Jerry