On Tue, 2022-01-25 at 17:02 +0800, GUO Zihua wrote:
> From: Guo Zihua <guozihua@xxxxxxxxxx>
>
> Commandline parameter ima_hash= and ima_template= has order requirement
> for them to work correctly together. Namely ima_hash= must be
> specified after ima_template=, otherwise ima_template= will be ignored.
>
> The reason is that when handling ima_hash=, ima template would be set to
> the default value if it has not been initialized already, and that value
> cannot be changed afterwards by ima_template=.
>
> This patch adds this limitation to the documentation.
>
> Reviewed-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
> Signed-off-by: Guo Zihua <guozihua@xxxxxxxxxx>
This issue should be limited to the original "ima" template format,
which only supports hash algorithms of 20 bytes or less. The "ima_ng"
template has been the default since larger digests and templates were
upstreamed back in Linux 3.13[1]. Do you really still have kernels
built with the original "ima" template?
[1] Refer to commit 4286587dccd4 ("ima: add Kconfig default measurement
list template").
thanks,
Mimi
> ---
> Documentation/admin-guide/kernel-parameters.txt | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index f5a27f067db9..1b5aa6ca65f8 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -1843,6 +1843,10 @@
> The list of supported hash algorithms is defined
> in crypto/hash_info.h.
>
> + This parameter must be specified after ima_template=,
> + as it would set the default template and that cannot be
> + changed by ima_template= afterwards.
> +
> ima_policy= [IMA]
> The builtin policies to load during IMA setup.
> Format: "tcb | appraise_tcb | secure_boot |
> @@ -1879,6 +1883,9 @@
> Formats: { "ima" | "ima-ng" | "ima-sig" }
> Default: "ima-ng"
>
> + This parameter must be specified before ima_hash=.
> + Please refer to ima_hash= for further explanation.
> +
> ima_template_fmt=
> [IMA] Define a custom template format.
> Format: { "field1|...|fieldN" }
