linux-kernel - Re: [PATCH] random: fix CRNG initialization when random.trust

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Date:   Fri, 19 Apr 2019 23:35:46 -0400
From:   "Theodore Ts'o" <tytso@....edu>
To:     Jon DeVree <nuxi@...lt24.org>
Cc:     linux-kernel@...r.kernel.org, Jason@...c4.com
Subject: Re: [PATCH] random: fix CRNG initialization when random.trust_cpu=1

On Tue, Mar 19, 2019 at 01:28:47PM -0400, Jon DeVree wrote:
> When the system boots with random.trust_cpu=1 it doesn't initialize the
> per-NUMA CRNGs because it skips the rest of the CRNG startup code. This
> means that the code from 1e7f583af67b ("random: make /dev/urandom scalable
> for silly userspace programs") is not used when random.trust_cpu=1.
> 
> crash> dmesg | grep random:
> [    0.000000] random: get_random_bytes called from start_kernel+0x94/0x530 with crng_init=0
> [    0.314029] random: crng done (trusting CPU's manufacturer)
> crash> print crng_node_pool
> $6 = (struct crng_state **) 0x0
> 
> After adding the missing call to numa_crng_init() the per-NUMA CRNGs are
> initialized again:
> 
> crash> dmesg | grep random:
> [    0.000000] random: get_random_bytes called from start_kernel+0x94/0x530 with crng_init=0
> [    0.314031] random: crng done (trusting CPU's manufacturer)
> crash> print crng_node_pool
> $1 = (struct crng_state **) 0xffff9a915f4014a0
> 
> The call to invalidate_batched_entropy() was also missing. This is
> important for architectures like PPC and S390 which only have the
> arch_get_random_seed_* functions.
> 
> Fixes: 39a8883a2b98 ("random: add a config option to trust the CPU's hwrng")
> Signed-off-by: Jon DeVree <nuxi@...lt24.org>

Thanks, applied.

					- Ted