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Commit 753d433b authored by Tobin C. Harding's avatar Tobin C. Harding Committed by Theodore Ts'o
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random: Return nbytes filled from hw RNG 



Currently the function get_random_bytes_arch() has return value 'void'.
If the hw RNG fails we currently fall back to using get_random_bytes().
This defeats the purpose of requesting random material from the hw RNG
in the first place.

There are currently no intree users of get_random_bytes_arch().

Only get random bytes from the hw RNG, make function return the number
of bytes retrieved from the hw RNG.

Acked-by: default avatarTheodore Ts'o <tytso@mit.edu>
Reviewed-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarTobin C. Harding <me@tobin.cc>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 8ddd6efa

drivers/char/random.c

+9 −7
Original line number Diff line number Diff line
@@ -1725,26 +1725,28 @@ EXPORT_SYMBOL(del_random_ready_callback); 
 * key known by the NSA).  So it's useful if we need the speed, but

 * only if we're willing to trust the hardware manufacturer not to

 * have put in a back door.

 *

 * Return number of bytes filled in.

 */

void get_random_bytes_arch(void *buf, int nbytes)

int __must_check get_random_bytes_arch(void *buf, int nbytes)

{

	int left = nbytes;

	char *p = buf;



	trace_get_random_bytes_arch(nbytes, _RET_IP_);

	while (nbytes) {

	trace_get_random_bytes_arch(left, _RET_IP_);

	while (left) {

		unsigned long v;

		int chunk = min(nbytes, (int)sizeof(unsigned long));

		int chunk = min_t(int, left, sizeof(unsigned long));



		if (!arch_get_random_long(&v))

			break;



		memcpy(p, &v, chunk);

		p += chunk;

		nbytes -= chunk;

		left -= chunk;

	}



	if (nbytes)

		get_random_bytes(p, nbytes);

	return nbytes - left;

}

EXPORT_SYMBOL(get_random_bytes_arch);

include/linux/random.h

+1 −1
Original line number Diff line number Diff line
@@ -38,7 +38,7 @@ 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);

extern int __must_check get_random_bytes_arch(void *buf, int nbytes);



#ifndef MODULE

extern const struct file_operations random_fops, urandom_fops;