Re: [ptxdist] [PATCH v4] ptxd_lib_code_signing: cs_get_ca(): improve error handling

[Michael Olbrich <m.olbrich@pengutronix.de>]

On Tue, Jul 13, 2021 at 01:51:25PM +0200, Roland Hieber wrote:
> From: Marc Kleine-Budde <mkl@pengutronix.de>
> 
> This patch changes cs_get_ca() to only output the CA if it actually
> exists, or print an error and return 1 instead. This makes it possible
> to use make's $(if $(filter-out, ERROR_CA_NOT_YET_SET, ...))
> conditional.
> 
> Co-authored-by: Roland Hieber <rhi@pengutronix.de>
> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
> Signed-off-by: Roland Hieber <rhi@pengutronix.de>
> ---
> PATCH v4:
>  - revert to [ -e "${ca}" ] test (feeback from Michael Olbrich and Marc
>    Kleine-Budde)
>  - add documentation too
> 
> PATCH v3: https://lore.ptxdist.org/ptxdist/20210708203941.30212-1-rhi@pengutronix.de
>  - correctly check for existence of ${keydir} instead of ${ca} (feedback
>    from Michael Olbrich)
>  - drop controversial re-indentation patches 6/7 and 7/7 from the series
> 
> PATCH v2 (rhi): https://lore.ptxdist.org/ptxdist/20210627231121.28313-1-rhi@pengutronix.de
>  - reorder from PATCH 3/n to PATCH 1/n
>  - echo "ERROR_CA_NOT_YET_SET" in case of error (feedback from Michael
>    Olbrich) and also return 1
> 
> PATCH v1 (mkl): https://lore.ptxdist.org/ptxdist/20210412161900.2376802-3-mkl@pengutronix.de
> 
> fixup! ptxd_lib_code_signing: cs_get_ca(): improve error handling
> ---
>  doc/ref_code_signing_helpers.rst     | 3 ++-
>  scripts/lib/ptxd_lib_code_signing.sh | 8 +++++++-
>  2 files changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/doc/ref_code_signing_helpers.rst b/doc/ref_code_signing_helpers.rst
> index 99a395b287c9..0fd61219a97a 100644
> --- a/doc/ref_code_signing_helpers.rst
> +++ b/doc/ref_code_signing_helpers.rst
> @@ -334,4 +334,5 @@ Preconditions:
>  
>  - a certificate must have been appended to the CA keyring
>    (see :ref:`cs_append_ca_from_pem`, :ref:`cs_append_ca_from_der`,
> -  :ref:`cs_append_ca_from_uri`)
> +  :ref:`cs_append_ca_from_uri`).
> +  Otherwise, this function will print ``ERROR_CA_NOT_YET_SET``.
> diff --git a/scripts/lib/ptxd_lib_code_signing.sh b/scripts/lib/ptxd_lib_code_signing.sh
> index 5fa62d8372f9..ca101d635574 100644
> --- a/scripts/lib/ptxd_lib_code_signing.sh
> +++ b/scripts/lib/ptxd_lib_code_signing.sh
> @@ -288,7 +288,13 @@ cs_get_ca() {
>      local role="${1}"
>      cs_init_variables
>  
> -    echo "${keydir}/${role}/ca.pem"
> +    local ca="${keydir}/${role}/ca.pem"
> +
> +    if [ ! -e "${ca}" ]; then
> +	echo "ERROR_CA_NOT_YET_SET"
> +	return 1
> +    fi
> +    echo "${ca}"

No. Please that's not what I meant. You need _both_!

There are three cases that need different output not two:

1. The function is called before the provider initialized the data:

    if [ ! -d "${keydir}" ]; then
	echo "ERROR_CA_NOT_YET_SET"
	return 1
    fi

2. The provider created a CA:

    if [ -e "${ca}" ]; then
	echo "${ca}"
    fi

3. The provider did _not_ create a CA:

   # no output

Case 1 is to detect misuse. And case 2 and 3 are needed to make the example
that Marc described possible.

Michael

>  }
>  export -f cs_get_ca
>  
> -- 
> 2.30.2
> 
> 
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