diff mbox series

[v3,3/8] random: Add GRND_INSECURE to return best-effort non-cryptographic bytes

Message ID d5473b56cf1fa900ca4bd2b3fc1e5b8874399919.1577088521.git.luto@kernel.org
State Not Applicable
Headers show
Series Rework random blocking | expand

Commit Message

Andy Lutomirski Dec. 23, 2019, 8:20 a.m. UTC 
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 drivers/char/random.c       | 11 +++++++++--
 include/uapi/linux/random.h |  2 ++
 2 files changed, 11 insertions(+), 2 deletions(-)

Comments

Theodore Ts'o Jan. 7, 2020, 8:44 p.m. UTC | #1 
On Mon, Dec 23, 2019 at 12:20:46AM -0800, Andy Lutomirski wrote:
> Signed-off-by: Andy Lutomirski <luto@kernel.org>

Applied, thanks.

					- Ted
diff mbox series

Patch

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 7b46751772e5..675b8a48e18a 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -2193,7 +2193,14 @@  SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
 {
 	int ret;
 
-	if (flags & ~(GRND_NONBLOCK|GRND_RANDOM))
+	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)
@@ -2202,7 +2209,7 @@  SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
 	if (flags & GRND_RANDOM)
 		return _random_read(flags & GRND_NONBLOCK, buf, count);
 
-	if (!crng_ready()) {
+	if (!(flags & GRND_INSECURE) && !crng_ready()) {
 		if (flags & GRND_NONBLOCK)
 			return -EAGAIN;
 		ret = wait_for_random_bytes();
diff --git a/include/uapi/linux/random.h b/include/uapi/linux/random.h
index 26ee91300e3e..c092d20088d3 100644
--- a/include/uapi/linux/random.h
+++ b/include/uapi/linux/random.h
@@ -49,8 +49,10 @@  struct rand_pool_info {
  *
  * GRND_NONBLOCK	Don't block and return EAGAIN instead
  * GRND_RANDOM		Use the /dev/random pool instead of /dev/urandom
+ * GRND_INSECURE	Return non-cryptographic random bytes
  */
 #define GRND_NONBLOCK	0x0001
 #define GRND_RANDOM	0x0002
+#define GRND_INSECURE	0x0004
 
 #endif /* _UAPI_LINUX_RANDOM_H */