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-rw-r--r--drivers/char/random.c15
-rw-r--r--lib/Kconfig.debug16
2 files changed, 29 insertions, 2 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 3853dd4f92e7..fa5bbd5a7ca0 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -288,7 +288,6 @@
#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))
@@ -1481,7 +1480,7 @@ 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);
@@ -2075,6 +2074,12 @@ u64 get_random_u64(void)
return ret;
#endif
+#ifdef CONFIG_WARN_UNSEEDED_RANDOM
+ if (!crng_ready())
+ printk(KERN_NOTICE "random: %pF get_random_u64 called "
+ "with crng_init = %d\n", (void *) _RET_IP_, crng_init);
+#endif
+
batch = &get_cpu_var(batched_entropy_u64);
if (use_lock)
read_lock_irqsave(&batched_entropy_reset_lock, flags);
@@ -2101,6 +2106,12 @@ u32 get_random_u32(void)
if (arch_get_random_int(&ret))
return ret;
+#ifdef CONFIG_WARN_UNSEEDED_RANDOM
+ if (!crng_ready())
+ printk(KERN_NOTICE "random: %pF get_random_u32 called "
+ "with crng_init = %d\n", (void *) _RET_IP_, crng_init);
+#endif
+
batch = &get_cpu_var(batched_entropy_u32);
if (use_lock)
read_lock_irqsave(&batched_entropy_reset_lock, flags);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index e4587ebe52c7..c4159605bfbf 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1209,6 +1209,22 @@ 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
+ depends on DEBUG_KERNEL
+ 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