[PATCH v3 4/5] random: Log how many bits we managed to seed with in init_std_data

Andy Lutomirski
2014-07-16T21:45:36Z

This is useful for making sure that init_std_data is working
correctly and for allaying fear when this happens:

random: xyz urandom read with SMALL_NUMBER bits of entropy available

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
---
drivers/char/random.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 17ad33d..10e9642 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1251,12 +1251,16 @@ static void init_std_data(struct entropy_store *r)
int i;
ktime_t now = ktime_get_real();
unsigned long rv;
+ int arch_seed_bits = 0, arch_random_bits = 0, slow_rng_bits = 0;

r->last_pulled = jiffies;
mix_pool_bytes(r, &now, sizeof(now), NULL);
for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) {
- if (!arch_get_random_seed_long(&rv) &&
- !arch_get_random_long(&rv))
+ if (arch_get_random_seed_long(&rv))
+ arch_seed_bits += 8 * sizeof(rv);
+ else if (arch_get_random_long(&rv))
+ arch_random_bits += 8 * sizeof(rv);
+ else
rv = random_get_entropy();
mix_pool_bytes(r, &rv, sizeof(rv), NULL);
}
@@ -1265,9 +1269,14 @@ static void init_std_data(struct entropy_store *r)
for (i = 0; i < 4; i++) {
u64 rv64;

- if (arch_get_slow_rng_u64(&rv64))
+ if (arch_get_slow_rng_u64(&rv64)) {
mix_pool_bytes(r, &rv64, sizeof(rv64), NULL);
+ slow_rng_bits += 8 * sizeof(rv64);
+ }
}
+
+ pr_info("random: seeded %s pool with %d bits of arch random seed, %d bits of arch random, and %d bits of arch slow rng\n",
+ r->name, arch_seed_bits, arch_random_bits, slow_rng_bits);
}

/*
--
1.9.3