linux-kernel - Re: [kernel-hardening] Re: [PATCH v4 06/13] iscsi: ensure RNG is seeded before use

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Message-ID: <02d60ed4-4207-dd7d-8826-0f9f7f4e966d@suse.com>
Date:   Fri, 16 Jun 2017 20:45:57 -0700
From:   Lee Duncan <lduncan@...e.com>
To:     "Jason A. Donenfeld" <Jason@...c4.com>
Cc:     Theodore Ts'o <tytso@....edu>,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel-hardening@...ts.openwall.com,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        David Miller <davem@...emloft.net>,
        Eric Biggers <ebiggers3@...il.com>,
        "Nicholas A. Bellinger" <nab@...ux-iscsi.org>,
        Chris Leech <cleech@...hat.com>, open-iscsi@...glegroups.com
Subject: Re: [kernel-hardening] Re: [PATCH v4 06/13] iscsi: ensure RNG is
 seeded before use

On 06/16/2017 05:41 PM, Jason A. Donenfeld wrote:
> Hi Lee,
> 
> On Fri, Jun 16, 2017 at 11:58 PM, Lee Duncan <lduncan@...e.com> wrote:
>> It seems like what you are doing is basically "good", i.e. if there is
>> not enough random data, don't use it. But what happens in that case? The
>> authentication fails? How does the user know to wait and try again?
> 
> The process just remains in interruptible (kill-able) sleep until
> there is enough entropy, so the process doesn't need to do anything.
> If the waiting is interrupted by a signal, it returns -ESYSRESTART,
> which follows the usual semantics of restartable syscalls.
> 
> Jason
> 

In your testing, how long might a process have to wait? Are we talking
seconds? Longer? What about timeouts?

Sorry, but your changing something that isn't exactly broken, so I just
want to be sure we're not introducing some regression, like clients
can't connect the first 5 minutes are a reboot.
-- 
Lee Duncan