Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 3a0a3365 authored by Jason A. Donenfeld's avatar Jason A. Donenfeld Committed by Greg Kroah-Hartman
Browse files

random: group userspace read/write functions 



commit a6adf8e7a605250b911e94793fd077933709ff9e upstream.

This pulls all of the userspace read/write-focused functions into the
fifth labeled section.

No functional changes.

Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: default avatarEric Biggers <ebiggers@google.com>
Reviewed-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0272b2bf

drivers/char/random.c

+77 −48
Original line number Diff line number Diff line
@@ -1473,30 +1473,61 @@ static void try_to_generate_entropy(void) 
	mix_pool_bytes(&stack.now, sizeof(stack.now));

}



static ssize_t urandom_read(struct file *file, char __user *buf, size_t nbytes,

			    loff_t *ppos)



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

 *

 * Userspace reader/writer interfaces.

 *

 * getrandom(2) is the primary modern interface into the RNG and should

 * be used in preference to anything else.

 *

 * Reading from /dev/random has the same functionality as calling

 * getrandom(2) with flags=0. In earlier versions, however, it had

 * vastly different semantics and should therefore be avoided, to

 * prevent backwards compatibility issues.

 *

 * Reading from /dev/urandom has the same functionality as calling

 * getrandom(2) with flags=GRND_INSECURE. Because it does not block

 * waiting for the RNG to be ready, it should not be used.

 *

 * Writing to either /dev/random or /dev/urandom adds entropy to

 * the input pool but does not credit it.

 *

 * Polling on /dev/random indicates when the RNG is initialized, on

 * the read side, and when it wants new entropy, on the write side.

 *

 * Both /dev/random and /dev/urandom have the same set of ioctls for

 * adding entropy, getting the entropy count, zeroing the count, and

 * reseeding the crng.

 *

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



SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, unsigned int,

		flags)

{

	static int maxwarn = 10;

	if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE))

		return -EINVAL;



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

		maxwarn--;

		if (__ratelimit(&urandom_warning))

			pr_notice("%s: uninitialized urandom read (%zd bytes read)\n",

				  current->comm, nbytes);

	}

	/*

	 * Requesting insecure and blocking randomness at the same time makes

	 * no sense.

	 */

	if ((flags & (GRND_INSECURE | GRND_RANDOM)) == (GRND_INSECURE | GRND_RANDOM))

		return -EINVAL;



	return get_random_bytes_user(buf, nbytes);

}

	if (count > INT_MAX)

		count = INT_MAX;



static ssize_t random_read(struct file *file, char __user *buf, size_t nbytes,

			   loff_t *ppos)

{

	if (!(flags & GRND_INSECURE) && !crng_ready()) {

		int ret;



		if (flags & GRND_NONBLOCK)

			return -EAGAIN;

		ret = wait_for_random_bytes();

	if (ret != 0)

		if (unlikely(ret))

			return ret;

	return get_random_bytes_user(buf, nbytes);

	}

	return get_random_bytes_user(buf, count);

}



static unsigned int random_poll(struct file *file, poll_table *wait)
@@ -1548,6 +1579,32 @@ static ssize_t random_write(struct file *file, const char __user *buffer, 
	return (ssize_t)count;

}



static ssize_t urandom_read(struct file *file, char __user *buf, size_t nbytes,

			    loff_t *ppos)

{

	static int maxwarn = 10;



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

		maxwarn--;

		if (__ratelimit(&urandom_warning))

			pr_notice("%s: uninitialized urandom read (%zd bytes read)\n",

				  current->comm, nbytes);

	}



	return get_random_bytes_user(buf, nbytes);

}



static ssize_t random_read(struct file *file, char __user *buf, size_t nbytes,

			   loff_t *ppos)

{

	int ret;



	ret = wait_for_random_bytes();

	if (ret != 0)

		return ret;

	return get_random_bytes_user(buf, nbytes);

}



static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)

{

	int size, ent_count;
@@ -1556,7 +1613,7 @@ static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) 


	switch (cmd) {

	case RNDGETENTCNT:

		/* inherently racy, no point locking */

		/* Inherently racy, no point locking. */

		if (put_user(input_pool.entropy_count, p))

			return -EFAULT;

		return 0;
@@ -1630,34 +1687,6 @@ const struct file_operations urandom_fops = { 
	.llseek = noop_llseek,

};



SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, unsigned int,

		flags)

{

	if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE))

		return -EINVAL;



	/*

	 * Requesting insecure and blocking randomness at the same time makes

	 * no sense.

	 */

	if ((flags & (GRND_INSECURE | GRND_RANDOM)) == (GRND_INSECURE | GRND_RANDOM))

		return -EINVAL;



	if (count > INT_MAX)

		count = INT_MAX;



	if (!(flags & GRND_INSECURE) && !crng_ready()) {

		int ret;



		if (flags & GRND_NONBLOCK)

			return -EAGAIN;

		ret = wait_for_random_bytes();

		if (unlikely(ret))

			return ret;

	}

	return get_random_bytes_user(buf, count);

}



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

 *

 * Sysctl interface