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random: add new ioctl RNDRESEEDCRNG 

Add a new ioctl which forces the the crng to be reseeded.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
This commit is contained in:
Theodore Ts'o 2018-04-11 16:32:17 -04:00
parent 0bb29a849a
commit d848e5f8e1
2 changed files with 15 additions and 1 deletions
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13
drivers/char/random.c
View File

@ -429,6 +429,7 @@ struct crng_state primary_crng = {
static int crng_init = 0; static int crng_init = 0;
#define crng_ready() (likely(crng_init > 1)) #define crng_ready() (likely(crng_init > 1))
static int crng_init_cnt = 0; static int crng_init_cnt = 0;
static unsigned long crng_global_init_time = 0;
#define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE) #define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE)
static void _extract_crng(struct crng_state *crng, static void _extract_crng(struct crng_state *crng,
__u32 out[CHACHA20_BLOCK_WORDS]); __u32 out[CHACHA20_BLOCK_WORDS]);
@ -933,7 +934,8 @@ static void _extract_crng(struct crng_state *crng,
unsigned long v, flags; unsigned long v, flags;
if (crng_ready() && if (crng_ready() &&
time_after(jiffies, crng->init_time + CRNG_RESEED_INTERVAL)) (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); crng_reseed(crng, crng == &primary_crng ? &input_pool : NULL);
spin_lock_irqsave(&crng->lock, flags); spin_lock_irqsave(&crng->lock, flags);
if (arch_get_random_long(&v)) if (arch_get_random_long(&v))
@ -1757,6 +1759,7 @@ static int rand_initialize(void)
init_std_data(&input_pool); init_std_data(&input_pool);
init_std_data(&blocking_pool); init_std_data(&blocking_pool);
crng_initialize(&primary_crng); crng_initialize(&primary_crng);
crng_global_init_time = jiffies;
return 0; return 0;
} }
early_initcall(rand_initialize); early_initcall(rand_initialize);
@ -1930,6 +1933,14 @@ static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
input_pool.entropy_count = 0; input_pool.entropy_count = 0;
blocking_pool.entropy_count = 0; blocking_pool.entropy_count = 0;
return 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: default:
return -EINVAL; return -EINVAL;
} }

3
include/uapi/linux/random.h
View File

@ -35,6 +35,9 @@
/* Clear the entropy pool and associated counters. (Superuser only.) */ /* Clear the entropy pool and associated counters. (Superuser only.) */
#define RNDCLEARPOOL _IO( 'R', 0x06 ) #define RNDCLEARPOOL _IO( 'R', 0x06 )
/* Reseed CRNG. (Superuser only.) */
#define RNDRESEEDCRNG _IO( 'R', 0x07 )
struct rand_pool_info { struct rand_pool_info {
int entropy_count; int entropy_count;
int buf_size; int buf_size;