Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <6c14d652-edb2-da32-4025-de1a234c828f@digikod.net>
Date:   Tue, 22 Mar 2022 11:53:07 +0100
MIME-Version: 1.0
User-Agent: 
Subject: Re: [PATCH v1 1/1] certs: Explain the rational to call panic()
Content-Language: en-US
To:     Paul Moore <paul@paul-moore.com>
Cc:     Jarkko Sakkinen <jarkko@kernel.org>,
        David Howells <dhowells@redhat.com>,
        "David S . Miller" <davem@davemloft.net>,
        David Woodhouse <dwmw2@infradead.org>,
        Eric Snowberg <eric.snowberg@oracle.com>,
        keyrings@vger.kernel.org, linux-crypto@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= <mic@linux.microsoft.com>
References: <20220321174548.510516-1-mic@digikod.net>
 <20220321174548.510516-2-mic@digikod.net>
 <CAHC9VhR+Ss5VAUHLutTvyS8g+agZy7d0YGcu_9dV1LBx_8ifNQ@mail.gmail.com>
From:   =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= <mic@digikod.net>
In-Reply-To: <CAHC9VhR+Ss5VAUHLutTvyS8g+agZy7d0YGcu_9dV1LBx_8ifNQ@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk


On 21/03/2022 19:23, Paul Moore wrote:
> On Mon, Mar 21, 2022 at 1:45 PM Mickaël Salaün <mic@digikod.net> wrote:
>>
>> From: Mickaël Salaün <mic@linux.microsoft.com>
>>
>> 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@paul-moore.com> [1]
>> Requested-by: Jarkko Sakkinen <jarkko@kernel.org> [1]
>> Link: https://lore.kernel.org/r/YjeW2r6Wv55Du0bJ@iki.fi [1]
>> Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
>> Link: https://lore.kernel.org/r/20220321174548.510516-2-mic@digikod.net
>> ---
>>   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@paul-moore.com>
> 
>> 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."

Thanks, I'll fix that.

> 
>> + * 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)
>>   {
> 
> --
> paul-moore.com