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

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Message-ID: <CAHmME9rU_H6Jq7ArjDq1yByrYf1P7nyC4Y8tqkzG585U39MFLg@mail.gmail.com>
Date:   Sat, 17 Jun 2017 02:41:39 +0200
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Lee Duncan <lduncan@...e.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

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