linux-kernel - Re: [PATCH] random: remove get_random_bytes_arch() and add rng_has_arch

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Date:   Tue, 17 May 2022 09:54:00 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     "Jason A. Donenfeld" <Jason@...c4.com>
Cc:     linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: Re: [PATCH] random: remove get_random_bytes_arch() and add
 rng_has_arch_random()

On Sat 2022-05-14 13:23:07, Jason A. Donenfeld wrote:
> The RNG incorporates RDRAND into its state at boot and every time it
> reseeds, so there's no reason for callers to use it directly. The
> hashing that the RNG does on it is preferable to using the bytes raw.
> 
> The only current use case of it is vsprintf's siphash key for pointer
> hashing, which uses it to initialize the pointer secret earlier than
> usual if RDRAND is available. In order to replace this narrow use case,
> just expose whether RDRAND is available. With that taken care of, there
> are no users of get_random_bytes_arch() left, so the function can be
> removed.
> 
> Later if trust_cpu gets turned on by default (as most distros are
> doing), this one use of rng_has_arch_random() can probably go away as
> well.
> 
> Cc: Petr Mladek <pmladek@...e.com>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Sergey Senozhatsky <senozhatsky@...omium.org>
> Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>

Looks good to me. Thanks for the clean up.

Acked-by: Petr Mladek <pmladek@...e.com>	# for vsprintf.c

Best Regards,
Petr