From 16b369a91d0dd80be214b7f7801fbc51875454cc Mon Sep 17 00:00:00 2001 From: Stephan Mueller Date: Mon, 25 May 2015 15:08:47 +0200 Subject: [PATCH] random: Blocking API for accessing nonblocking_pool The added API calls provide a synchronous function call get_blocking_random_bytes where the caller is blocked until the nonblocking_pool is initialized. CC: Andreas Steffen CC: Theodore Ts'o CC: Sandy Harris Signed-off-by: Stephan Mueller Signed-off-by: Herbert Xu --- drivers/char/random.c | 12 ++++++++++++ include/linux/random.h | 1 + 2 files changed, 13 insertions(+) diff --git a/drivers/char/random.c b/drivers/char/random.c index 8b8c46b5fd5c..159d0700f7d8 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1244,6 +1244,18 @@ void get_random_bytes(void *buf, int nbytes) } EXPORT_SYMBOL(get_random_bytes); +/* + * Equivalent function to get_random_bytes with the difference that this + * function blocks the request until the nonblocking_pool is initialized. + */ +void get_blocking_random_bytes(void *buf, int nbytes) +{ + if (unlikely(nonblocking_pool.initialized == 0)) + wait_event(urandom_init_wait, nonblocking_pool.initialized); + extract_entropy(&nonblocking_pool, buf, nbytes, 0, 0); +} +EXPORT_SYMBOL(get_blocking_random_bytes); + /* * This function will use the architecture-specific hardware random * number generator if it is available. The arch-specific hw RNG will diff --git a/include/linux/random.h b/include/linux/random.h index b05856e16b75..796267d56901 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -14,6 +14,7 @@ extern void add_input_randomness(unsigned int type, unsigned int code, extern void add_interrupt_randomness(int irq, int irq_flags); extern void get_random_bytes(void *buf, int nbytes); +extern void get_blocking_random_bytes(void *buf, int nbytes); extern void get_random_bytes_arch(void *buf, int nbytes); void generate_random_uuid(unsigned char uuid_out[16]); extern int random_int_secret_init(void);