random: add wait_for_random_bytes() API (e297a783) · Commits · 戴 / test

drivers/char/random.c

+31 −10

Original line number	Diff line number	Diff line
		@@ -851,11 +851,6 @@ static void crng_reseed(struct crng_state crng, struct entropy_store r)
		}
		}

		static inline void crng_wait_ready(void)
		{
		wait_event_interruptible(crng_init_wait, crng_ready());
		}

		static void _extract_crng(struct crng_state *crng,
		__u8 out[CHACHA20_BLOCK_SIZE])
		{
		@@ -1477,7 +1472,10 @@ static ssize_t extract_entropy_user(struct entropy_store r, void __user buf,
		* number of good random numbers, suitable for key generation, seeding
		* TCP sequence numbers, etc. It does not rely on the hardware random
		* number generator. For random bytes direct from the hardware RNG
		* (when available), use get_random_bytes_arch().
		* (when available), use get_random_bytes_arch(). In order to ensure
		* that the randomness provided by this function is okay, the function
		* wait_for_random_bytes() should be called and return 0 at least once
		* at any point prior.
		*/
		void get_random_bytes(void *buf, int nbytes)
		{
		@@ -1506,6 +1504,24 @@ void get_random_bytes(void *buf, int nbytes)
		}
		EXPORT_SYMBOL(get_random_bytes);

		/*
		* Wait for the urandom pool to be seeded and thus guaranteed to supply
		* cryptographically secure random numbers. This applies to: the /dev/urandom
		* device, the get_random_bytes function, and the get_random_{u32,u64,int,long}
		* family of functions. Using any of these functions without first calling
		* this function forfeits the guarantee of security.
		*
		* Returns: 0 if the urandom pool has been seeded.
		* -ERESTARTSYS if the function was interrupted by a signal.
		*/
		int wait_for_random_bytes(void)
		{
		if (likely(crng_ready()))
		return 0;
		return wait_event_interruptible(crng_init_wait, crng_ready());
		}
		EXPORT_SYMBOL(wait_for_random_bytes);

		/*
		* Add a callback function that will be invoked when the nonblocking
		* pool is initialised.
		@@ -1860,6 +1876,8 @@ const struct file_operations urandom_fops = {
		SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
		unsigned int, flags)
		{
		int ret;

		if (flags & ~(GRND_NONBLOCK\|GRND_RANDOM))
		return -EINVAL;

		@@ -1872,9 +1890,9 @@ SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
		if (!crng_ready()) {
		if (flags & GRND_NONBLOCK)
		return -EAGAIN;
		crng_wait_ready();
		if (signal_pending(current))
		return -ERESTARTSYS;
		ret = wait_for_random_bytes();
		if (unlikely(ret))
		return ret;
		}
		return urandom_read(NULL, buf, count, NULL);
		}
		@@ -2035,7 +2053,10 @@ static rwlock_t batched_entropy_reset_lock = __RW_LOCK_UNLOCKED(batched_entropy_
		/*
		* Get a random word for internal kernel use only. The quality of the random
		* number is either as good as RDRAND or as good as /dev/urandom, with the
		* goal of being quite fast and not depleting entropy.
		* goal of being quite fast and not depleting entropy. In order to ensure
		* that the randomness provided by this function is okay, the function
		* wait_for_random_bytes() should be called and return 0 at least once
		* at any point prior.
		*/
		static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64);
		u64 get_random_u64(void)

include/linux/random.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -34,6 +34,7 @@ extern void add_input_randomness(unsigned int type, unsigned int code,
		extern void add_interrupt_randomness(int irq, int irq_flags) __latent_entropy;

		extern void get_random_bytes(void *buf, int nbytes);
		extern int wait_for_random_bytes(void);
		extern int add_random_ready_callback(struct random_ready_callback *rdy);
		extern void del_random_ready_callback(struct random_ready_callback *rdy);
		extern void get_random_bytes_arch(void *buf, int nbytes);

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