linux-kernel - Re: [PATCH 2/3] integrity: Move import of MokListRT certs to a separate routine

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Message-ID: <ada8f771-5717-58f1-8352-feffea8703b4@redhat.com>
Date:   Fri, 4 Sep 2020 20:57:57 -0400
From:   Lenny Szubowicz <lszubowi@...hat.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-efi <linux-efi@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        linux-security-module <linux-security-module@...r.kernel.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Kees Cook <keescook@...omium.org>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Borislav Petkov <bp@...en8.de>,
        Peter Jones <pjones@...hat.com>,
        David Howells <dhowells@...hat.com>,
        Prarit Bhargava <prarit@...hat.com>
Subject: Re: [PATCH 2/3] integrity: Move import of MokListRT certs to a
 separate routine

On 9/2/20 3:55 AM, Andy Shevchenko wrote:
> On Wed, Aug 26, 2020 at 6:45 AM Lenny Szubowicz <lszubowi@...hat.com> wrote:
>>
>> Move the loading of certs from the UEFI MokListRT into a separate
>> routine to facilitate additional MokList functionality.
>>
>> There is no visible functional change as a result of this patch.
>> Although the UEFI dbx certs are now loaded before the MokList certs,
>> they are loaded onto different key rings. So the order of the keys
>> on their respective key rings is the same.
> 
> ...
> 
>>   /*
>> + * load_moklist_certs() - Load MokList certs
>> + *
>> + * Returns:    Summary error status
>> + *
>> + * Load the certs contained in the UEFI MokListRT database into the
>> + * platform trusted keyring.
>> + */
> 
> Hmm... Is it intentionally kept out of kernel doc format?

Yes. Since this is a static local routine, I thought that it
shouldn't be included by kerneldoc. But I wanted to generally adhere
to the kernel doc conventions for a routine header. To that end,
in V2 I move the "Return:" section to come after the short description.

> 
>> +static int __init load_moklist_certs(void)
>> +{
>> +       efi_guid_t mok_var = EFI_SHIM_LOCK_GUID;
>> +       void *mok = NULL;
>> +       unsigned long moksize = 0;
>> +       efi_status_t status;
>> +       int rc = 0;
> 
> Redundant assignment (see below).
> 
>> +       /* Get MokListRT. It might not exist, so it isn't an error
>> +        * if we can't get it.
>> +        */
>> +       mok = get_cert_list(L"MokListRT", &mok_var, &moksize, &status);
> 
>> +       if (!mok) {
> 
> Why not positive conditional? Sometimes ! is hard to notice.
> 
>> +               if (status == EFI_NOT_FOUND)
>> +                       pr_debug("MokListRT variable wasn't found\n");
>> +               else
>> +                       pr_info("Couldn't get UEFI MokListRT\n");
>> +       } else {
>> +               rc = parse_efi_signature_list("UEFI:MokListRT",
>> +                                             mok, moksize, get_handler_for_db);
>> +               if (rc)
>> +                       pr_err("Couldn't parse MokListRT signatures: %d\n", rc);
>> +               kfree(mok);
> 
>   kfree(...)
>   if (rc)
>    ...
>   return rc;
> 
> And with positive conditional there will be no need to have redundant
> 'else' followed by additional level of indentation.
> 
>> +       }
> 
>> +       return rc;
> 
> return 0;
> 
>> +}
> 
> P.S. Yes, I see that the above was in the original code, so, consider
> my comments as suggestions to improve the code.
> 

I agree that your suggestions improve the code. I've incorporated this
into V2.

                        -Lenny.