diff options
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/random.c | 68 |
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; |