@@ -285,7 +285,6 @@
#define SEC_XFER_SIZE 512
#define EXTRACT_SIZE 10
-#define DEBUG_RANDOM_BOOT 0
#define LONGS(x) (((x) + sizeof(unsigned long) - 1)/sizeof(unsigned long))
@@ -1470,7 +1469,7 @@ void get_random_bytes(void *buf, int nbytes)
{
__u8 tmp[CHACHA20_BLOCK_SIZE];
-#if DEBUG_RANDOM_BOOT > 0
+#ifdef CONFIG_WARN_UNSEEDED_RANDOM
if (!crng_ready())
printk(KERN_NOTICE "random: %pF get_random_bytes called "
"with crng_init = %d\n", (void *) _RET_IP_, crng_init);
@@ -1209,6 +1209,21 @@ config STACKTRACE
It is also used by various kernel debugging features that require
stack trace generation.
+config WARN_UNSEEDED_RANDOM
+ bool "Warn when kernel uses unseeded randomness"
+ default y
+ help
+ Some parts of the kernel contain bugs relating to their use of
+ cryptographically secure random numbers before it's actually possible
+ to generate those numbers securely. This setting ensures that these
+ flaws don't go unnoticed, by enabling a message, should this ever
+ occur. This will allow people with obscure setups to know when things
+ are going wrong, so that they might contact developers about fixing
+ it.
+
+ Say Y here, unless you simply do not care about using unseeded
+ randomness and do not want a potential warning message in your logs.
+
config DEBUG_KOBJECT
bool "kobject debugging"
depends on DEBUG_KERNEL
This enables an important dmesg notification about when drivers have used the crng without it being seeded first. Prior, these errors would occur silently, and so there hasn't been a great way of diagnosing these types of bugs for obscure setups. By adding this as a config option, we can leave it on by default, so that we learn where these issues happen, in the field, will still allowing some people to turn it off, if they really know what they're doing and do not want the log entries. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> --- drivers/char/random.c | 3 +-- lib/Kconfig.debug | 15 +++++++++++++++ 2 files changed, 16 insertions(+), 2 deletions(-)