[PATCH 5.4 022/240] random: split primary/secondary crng init paths

Greg Kroah-Hartman
2022-06-20T13:34:37Z

From: Mark Rutland <mark.rutland@arm.com>

commit 5cbe0f13b51ac2fb2fd55902cff8d0077fc084c0 upstream.

Currently crng_initialize() is used for both the primary CRNG and
secondary CRNGs. While we wish to share common logic, we need to do a
number of additional things for the primary CRNG, and this would be
easier to deal with were these handled in separate functions.

This patch splits crng_initialize() into crng_initialize_primary() and
crng_initialize_secondary(), with common logic factored out into a
crng_init_try_arch() helper.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20200210130015.17664-2-mark.rutland@arm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 34 ++++++++++++++++++++++------------
1 file changed, 22 insertions(+), 12 deletions(-)

--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -782,27 +782,37 @@ static int __init parse_trust_cpu(char *
}
early_param("random.trust_cpu", parse_trust_cpu);

-static void crng_initialize(struct crng_state *crng)
+static bool crng_init_try_arch(struct crng_state *crng)
{
int i;
- int arch_init = 1;
+ bool arch_init = true;
unsigned long rv;

- memcpy(&crng->state[0], "expand 32-byte k", 16);
- if (crng == &primary_crng)
- _extract_entropy(&input_pool, &crng->state[4],
- sizeof(__u32) * 12, 0);
- else
- _get_random_bytes(&crng->state[4], sizeof(__u32) * 12);
for (i = 4; i < 16; i++) {
if (!arch_get_random_seed_long(&rv) &&
!arch_get_random_long(&rv)) {
rv = random_get_entropy();
- arch_init = 0;
+ arch_init = false;
}
crng->state[i] ^= rv;
}
- if (trust_cpu && arch_init && crng == &primary_crng) {
+
+ return arch_init;
+}
+
+static void crng_initialize_secondary(struct crng_state *crng)
+{
+ memcpy(&crng->state[0], "expand 32-byte k", 16);
+ _get_random_bytes(&crng->state[4], sizeof(__u32) * 12);
+ crng_init_try_arch(crng);
+ crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
+}
+
+static void __init crng_initialize_primary(struct crng_state *crng)
+{
+ memcpy(&crng->state[0], "expand 32-byte k", 16);
+ _extract_entropy(&input_pool, &crng->state[4], sizeof(__u32) * 12, 0);
+ if (crng_init_try_arch(crng) && trust_cpu) {
invalidate_batched_entropy();
numa_crng_init();
crng_init = 2;
@@ -853,7 +863,7 @@ static void do_numa_crng_init(struct wor
crng = kmalloc_node(sizeof(struct crng_state),
GFP_KERNEL | __GFP_NOFAIL, i);
spin_lock_init(&crng->lock);
- crng_initialize(crng);
+ crng_initialize_secondary(crng);
pool[i] = crng;
}
/* pairs with READ_ONCE() in select_crng() */
@@ -1793,7 +1803,7 @@ int __init rand_initialize(void)
init_std_data(&input_pool);
if (crng_need_final_init)
crng_finalize_init(&primary_crng);
- crng_initialize(&primary_crng);
+ crng_initialize_primary(&primary_crng);
crng_global_init_time = jiffies;
if (ratelimit_disable) {
urandom_warning.interval = 0;