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-rw-r--r--drivers/char/random.c68
1 files changed, 32 insertions, 36 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 94990b052f58..65ee69896967 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -182,7 +182,6 @@ enum {
static struct {
u8 key[CHACHA_KEY_SIZE] __aligned(__alignof__(long));
- unsigned long birth;
unsigned long generation;
spinlock_t lock;
} base_crng = {
@@ -200,16 +199,41 @@ static DEFINE_PER_CPU(struct crng, crngs) = {
.lock = INIT_LOCAL_LOCK(crngs.lock),
};
+/*
+ * Return the interval until the next reseeding, which is normally
+ * CRNG_RESEED_INTERVAL, but during early boot, it is at an interval
+ * proportional to the uptime.
+ */
+static unsigned int crng_reseed_interval(void)
+{
+ static bool early_boot = true;
+
+ if (unlikely(READ_ONCE(early_boot))) {
+ time64_t uptime = ktime_get_seconds();
+ if (uptime >= CRNG_RESEED_INTERVAL / HZ * 2)
+ WRITE_ONCE(early_boot, false);
+ else
+ return max_t(unsigned int, CRNG_RESEED_START_INTERVAL,
+ (unsigned int)uptime / 2 * HZ);
+ }
+ return CRNG_RESEED_INTERVAL;
+}
+
/* Used by crng_reseed() and crng_make_state() to extract a new seed from the input pool. */
static void extract_entropy(void *buf, size_t len);
/* This extracts a new crng key from the input pool. */
-static void crng_reseed(void)
+static void crng_reseed(struct work_struct *work)
{
+ static DECLARE_DELAYED_WORK(next_reseed, crng_reseed);
unsigned long flags;
unsigned long next_gen;
u8 key[CHACHA_KEY_SIZE];
+ /* Immediately schedule the next reseeding, so that it fires sooner rather than later. */
+ if (likely(system_unbound_wq))
+ queue_delayed_work(system_unbound_wq, &next_reseed, crng_reseed_interval());
+
extract_entropy(key, sizeof(key));
/*
@@ -224,7 +248,6 @@ static void crng_reseed(void)
if (next_gen == ULONG_MAX)
++next_gen;
WRITE_ONCE(base_crng.generation, next_gen);
- WRITE_ONCE(base_crng.birth, jiffies);
if (!static_branch_likely(&crng_is_ready))
crng_init = CRNG_READY;
spin_unlock_irqrestore(&base_crng.lock, flags);
@@ -264,26 +287,6 @@ static void crng_fast_key_erasure(u8 key[CHACHA_KEY_SIZE],
}
/*
- * Return the interval until the next reseeding, which is normally
- * CRNG_RESEED_INTERVAL, but during early boot, it is at an interval
- * proportional to the uptime.
- */
-static unsigned int crng_reseed_interval(void)
-{
- static bool early_boot = true;
-
- if (unlikely(READ_ONCE(early_boot))) {
- time64_t uptime = ktime_get_seconds();
- if (uptime >= CRNG_RESEED_INTERVAL / HZ * 2)
- WRITE_ONCE(early_boot, false);
- else
- return max_t(unsigned int, CRNG_RESEED_START_INTERVAL,
- (unsigned int)uptime / 2 * HZ);
- }
- return CRNG_RESEED_INTERVAL;
-}
-
-/*
* This function returns a ChaCha state that you may use for generating
* random data. It also returns up to 32 bytes on its own of random data
* that may be used; random_data_len may not be greater than 32.
@@ -318,13 +321,6 @@ static void crng_make_state(u32 chacha_state[CHACHA_STATE_WORDS],
return;
}
- /*
- * If the base_crng is old enough, we reseed, which in turn bumps the
- * generation counter that we check below.
- */
- if (unlikely(time_is_before_jiffies(READ_ONCE(base_crng.birth) + crng_reseed_interval())))
- crng_reseed();
-
local_lock_irqsave(&crngs.lock, flags);
crng = raw_cpu_ptr(&crngs);
@@ -698,7 +694,7 @@ static void __cold _credit_init_bits(size_t bits)
} while (!try_cmpxchg(&input_pool.init_bits, &orig, new));
if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) {
- crng_reseed(); /* Sets crng_init to CRNG_READY under base_crng.lock. */
+ crng_reseed(NULL); /* Sets crng_init to CRNG_READY under base_crng.lock. */
if (static_key_initialized)
execute_in_process_context(crng_set_ready, &set_ready);
wake_up_interruptible(&crng_init_wait);
@@ -806,7 +802,7 @@ static int random_pm_notification(struct notifier_block *nb, unsigned long actio
if (crng_ready() && (action == PM_RESTORE_PREPARE ||
(action == PM_POST_SUSPEND && !IS_ENABLED(CONFIG_PM_AUTOSLEEP) &&
!IS_ENABLED(CONFIG_PM_USERSPACE_AUTOSLEEP)))) {
- crng_reseed();
+ crng_reseed(NULL);
pr_notice("crng reseeded on system resumption\n");
}
return 0;
@@ -850,7 +846,7 @@ void __init random_init_early(const char *command_line)
/* Reseed if already seeded by earlier phases. */
if (crng_ready())
- crng_reseed();
+ crng_reseed(NULL);
else if (trust_cpu)
_credit_init_bits(arch_bits);
}
@@ -878,7 +874,7 @@ void __init random_init(void)
/* Reseed if already seeded by earlier phases. */
if (crng_ready())
- crng_reseed();
+ crng_reseed(NULL);
WARN_ON(register_pm_notifier(&pm_notifier));
@@ -948,7 +944,7 @@ void __cold add_vmfork_randomness(const void *unique_vm_id, size_t len)
{
add_device_randomness(unique_vm_id, len);
if (crng_ready()) {
- crng_reseed();
+ crng_reseed(NULL);
pr_notice("crng reseeded due to virtual machine fork\n");
}
blocking_notifier_call_chain(&vmfork_chain, 0, NULL);
@@ -1470,7 +1466,7 @@ static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
return -EPERM;
if (!crng_ready())
return -ENODATA;
- crng_reseed();
+ crng_reseed(NULL);
return 0;
default:
return -EINVAL;