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Commit 479d3970 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Greg Kroah-Hartman
Browse files

random: Add a urandom_read_nowait() for random APIs that don't warn 



commit c6f1deb158789abba02a7eba600747843eeb3a57 upstream.

/dev/random and getrandom() never warn.  Split the meat of
urandom_read() into urandom_read_nowarn() and leave the warning code
in urandom_read().

This has no effect on kernel behavior, but it makes subsequent
patches more straightforward.  It also makes the fact that
getrandom() never warns more obvious.

Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/c87ab200588de746431d9f916501ef11e5242b13.1577088521.git.luto@kernel.org


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 69441ba5

drivers/char/random.c

+15 −6
Original line number Diff line number Diff line
@@ -2042,12 +2042,23 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) 
	return _random_read(file->f_flags & O_NONBLOCK, buf, nbytes);

}



static ssize_t

urandom_read_nowarn(struct file *file, char __user *buf, size_t nbytes,

		    loff_t *ppos)

{

	int ret;



	nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3));

	ret = extract_crng_user(buf, nbytes);

	trace_urandom_read(8 * nbytes, 0, ENTROPY_BITS(&input_pool));

	return ret;

}



static ssize_t

urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)

{

	unsigned long flags;

	static int maxwarn = 10;

	int ret;



	if (!crng_ready() && maxwarn > 0) {

		maxwarn--;
@@ -2059,10 +2070,8 @@ urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) 
		crng_init_cnt = 0;

		spin_unlock_irqrestore(&primary_crng.lock, flags);

	}

	nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3));

	ret = extract_crng_user(buf, nbytes);

	trace_urandom_read(8 * nbytes, 0, ENTROPY_BITS(&input_pool));

	return ret;



	return urandom_read_nowarn(file, buf, nbytes, ppos);

}



static __poll_t
@@ -2224,7 +2233,7 @@ SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, 
		if (unlikely(ret))

			return ret;

	}

	return urandom_read(NULL, buf, count, NULL);

	return urandom_read_nowarn(NULL, buf, count, NULL);

}



/********************************************************************