Re: [PATCH v1 1/1] certs: Explain the rational to call panic()

[Paul Moore]

On Mon, Mar 21, 2022 at 1:45 PM Mickaël Salaün <mic@xxxxxxxxxxx> wrote:
>
> From: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx>
>
> The blacklist_init() function calls panic() for memory allocation
> errors.  This change documents the reason why we don't return -ENODEV.
>
> Suggested-by: Paul Moore <paul@xxxxxxxxxxxxxx> [1]
> Requested-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> [1]
> Link: https://lore.kernel.org/r/YjeW2r6Wv55Du0bJ@xxxxxx [1]
> Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx>
> Link: https://lore.kernel.org/r/20220321174548.510516-2-mic@xxxxxxxxxxx
> ---
>  certs/blacklist.c | 8 ++++++++
>  1 file changed, 8 insertions(+)

I would suggest changing the second sentence as shown below, but
otherwise it looks good to me.

Reviewed-by: Paul Moore <paul@xxxxxxxxxxxxxx>

> diff --git a/certs/blacklist.c b/certs/blacklist.c
> index 486ce0dd8e9c..ac26bcf9b9a5 100644
> --- a/certs/blacklist.c
> +++ b/certs/blacklist.c
> @@ -307,6 +307,14 @@ static int restrict_link_for_blacklist(struct key *dest_keyring,
>
>  /*
>   * Initialise the blacklist
> + *
> + * The blacklist_init() function is registered as an initcall via
> + * device_initcall().  As a result the functionality doesn't load and the

"As a result if the blacklist_init() function fails for any reason the
kernel continues to execute."

> + * kernel continues on executing.  While cleanly returning -ENODEV could be
> + * acceptable for some non-critical kernel parts, if the blacklist keyring
> + * fails to load it defeats the certificate/key based deny list for signed
> + * modules.  If a critical piece of security functionality that users expect to
> + * be present fails to initialize, panic()ing is likely the right thing to do.
>   */
>  static int __init blacklist_init(void)
>  {

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