diff options
Diffstat (limited to 'drivers/char/random.c')
| -rw-r--r-- | drivers/char/random.c | 128 |
1 files changed, 97 insertions, 31 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index e027e7fa1472..3cd3aae24d6d 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -427,8 +427,9 @@ struct crng_state primary_crng = { * its value (from 0->1->2). */ static int crng_init = 0; -#define crng_ready() (likely(crng_init > 0)) +#define crng_ready() (likely(crng_init > 1)) static int crng_init_cnt = 0; +static unsigned long crng_global_init_time = 0; #define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE) static void _extract_crng(struct crng_state *crng, __u32 out[CHACHA20_BLOCK_WORDS]); @@ -787,6 +788,36 @@ static void crng_initialize(struct crng_state *crng) crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1; } +#ifdef CONFIG_NUMA +static void numa_crng_init(void) +{ + int i; + struct crng_state *crng; + struct crng_state **pool; + + pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL|__GFP_NOFAIL); + for_each_online_node(i) { + crng = kmalloc_node(sizeof(struct crng_state), + GFP_KERNEL | __GFP_NOFAIL, i); + spin_lock_init(&crng->lock); + crng_initialize(crng); + pool[i] = crng; + } + mb(); + if (cmpxchg(&crng_node_pool, NULL, pool)) { + for_each_node(i) + kfree(pool[i]); + kfree(pool); + } +} +#else +static void numa_crng_init(void) {} +#endif + +/* + * crng_fast_load() can be called by code in the interrupt service + * path. So we can't afford to dilly-dally. + */ static int crng_fast_load(const char *cp, size_t len) { unsigned long flags; @@ -794,7 +825,7 @@ static int crng_fast_load(const char *cp, size_t len) if (!spin_trylock_irqsave(&primary_crng.lock, flags)) return 0; - if (crng_ready()) { + if (crng_init != 0) { spin_unlock_irqrestore(&primary_crng.lock, flags); return 0; } @@ -813,6 +844,51 @@ static int crng_fast_load(const char *cp, size_t len) return 1; } +/* + * crng_slow_load() is called by add_device_randomness, which has two + * attributes. (1) We can't trust the buffer passed to it is + * guaranteed to be unpredictable (so it might not have any entropy at + * all), and (2) it doesn't have the performance constraints of + * crng_fast_load(). + * + * So we do something more comprehensive which is guaranteed to touch + * all of the primary_crng's state, and which uses a LFSR with a + * period of 255 as part of the mixing algorithm. Finally, we do + * *not* advance crng_init_cnt since buffer we may get may be something + * like a fixed DMI table (for example), which might very well be + * unique to the machine, but is otherwise unvarying. + */ +static int crng_slow_load(const char *cp, size_t len) +{ + unsigned long flags; + static unsigned char lfsr = 1; + unsigned char tmp; + unsigned i, max = CHACHA20_KEY_SIZE; + const char * src_buf = cp; + char * dest_buf = (char *) &primary_crng.state[4]; + + if (!spin_trylock_irqsave(&primary_crng.lock, flags)) + return 0; + if (crng_init != 0) { + spin_unlock_irqrestore(&primary_crng.lock, flags); + return 0; + } + if (len > max) + max = len; + + for (i = 0; i < max ; i++) { + tmp = lfsr; + lfsr >>= 1; + if (tmp & 1) + lfsr ^= 0xE1; + tmp = dest_buf[i % CHACHA20_KEY_SIZE]; + dest_buf[i % CHACHA20_KEY_SIZE] ^= src_buf[i % len] ^ lfsr; + lfsr += (tmp << 3) | (tmp >> 5); + } + spin_unlock_irqrestore(&primary_crng.lock, flags); + return 1; +} + static void crng_reseed(struct crng_state *crng, struct entropy_store *r) { unsigned long flags; @@ -831,7 +907,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r) _crng_backtrack_protect(&primary_crng, buf.block, CHACHA20_KEY_SIZE); } - spin_lock_irqsave(&primary_crng.lock, flags); + spin_lock_irqsave(&crng->lock, flags); for (i = 0; i < 8; i++) { unsigned long rv; if (!arch_get_random_seed_long(&rv) && @@ -841,9 +917,10 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r) } memzero_explicit(&buf, sizeof(buf)); crng->init_time = jiffies; - spin_unlock_irqrestore(&primary_crng.lock, flags); + spin_unlock_irqrestore(&crng->lock, flags); if (crng == &primary_crng && crng_init < 2) { invalidate_batched_entropy(); + numa_crng_init(); crng_init = 2; process_random_ready_list(); wake_up_interruptible(&crng_init_wait); @@ -856,8 +933,9 @@ static void _extract_crng(struct crng_state *crng, { unsigned long v, flags; - if (crng_init > 1 && - time_after(jiffies, crng->init_time + CRNG_RESEED_INTERVAL)) + if (crng_ready() && + (time_after(crng_global_init_time, crng->init_time) || + time_after(jiffies, crng->init_time + CRNG_RESEED_INTERVAL))) crng_reseed(crng, crng == &primary_crng ? &input_pool : NULL); spin_lock_irqsave(&crng->lock, flags); if (arch_get_random_long(&v)) @@ -981,10 +1059,8 @@ void add_device_randomness(const void *buf, unsigned int size) unsigned long time = random_get_entropy() ^ jiffies; unsigned long flags; - if (!crng_ready()) { - crng_fast_load(buf, size); - return; - } + if (!crng_ready() && size) + crng_slow_load(buf, size); trace_add_device_randomness(size, _RET_IP_); spin_lock_irqsave(&input_pool.lock, flags); @@ -1139,7 +1215,7 @@ void add_interrupt_randomness(int irq, int irq_flags) fast_mix(fast_pool); add_interrupt_bench(cycles); - if (!crng_ready()) { + if (unlikely(crng_init == 0)) { if ((fast_pool->count >= 64) && crng_fast_load((char *) fast_pool->pool, sizeof(fast_pool->pool))) { @@ -1680,28 +1756,10 @@ static void init_std_data(struct entropy_store *r) */ static int rand_initialize(void) { -#ifdef CONFIG_NUMA - int i; - struct crng_state *crng; - struct crng_state **pool; -#endif - init_std_data(&input_pool); init_std_data(&blocking_pool); crng_initialize(&primary_crng); - -#ifdef CONFIG_NUMA - pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL|__GFP_NOFAIL); - for_each_online_node(i) { - crng = kmalloc_node(sizeof(struct crng_state), - GFP_KERNEL | __GFP_NOFAIL, i); - spin_lock_init(&crng->lock); - crng_initialize(crng); - pool[i] = crng; - } - mb(); - crng_node_pool = pool; -#endif + crng_global_init_time = jiffies; return 0; } early_initcall(rand_initialize); @@ -1875,6 +1933,14 @@ static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) input_pool.entropy_count = 0; blocking_pool.entropy_count = 0; return 0; + case RNDRESEEDCRNG: + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + if (crng_init < 2) + return -ENODATA; + crng_reseed(&primary_crng, NULL); + crng_global_init_time = jiffies - 1; + return 0; default: return -EINVAL; } @@ -2212,7 +2278,7 @@ void add_hwgenerator_randomness(const char *buffer, size_t count, { struct entropy_store *poolp = &input_pool; - if (!crng_ready()) { + if (unlikely(crng_init == 0)) { crng_fast_load(buffer, count); return; } |