This is a note to let you know that I've just added the patch titled random: add GRND_INSECURE to return best-effort non-cryptographic bytes to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: random-add-grnd_insecure-to-return-best-effort-non-cryptographic-bytes.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Thu Jun 16 07:08:33 PM CEST 2022 From: Andy Lutomirski <luto@xxxxxxxxxx> Date: Mon, 23 Dec 2019 00:20:46 -0800 Subject: random: add GRND_INSECURE to return best-effort non-cryptographic bytes From: Andy Lutomirski <luto@xxxxxxxxxx> commit 75551dbf112c992bc6c99a972990b3f272247e23 upstream. Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx> Link: https://lore.kernel.org/r/d5473b56cf1fa900ca4bd2b3fc1e5b8874399919.1577088521.git.luto@xxxxxxxxxx Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/char/random.c | 11 +++++++++-- include/uapi/linux/random.h | 2 ++ 2 files changed, 11 insertions(+), 2 deletions(-) --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -2134,7 +2134,14 @@ SYSCALL_DEFINE3(getrandom, char __user * { 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) @@ -2143,7 +2150,7 @@ SYSCALL_DEFINE3(getrandom, char __user * 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(); --- 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 */ Patches currently in stable-queue which might be from luto@xxxxxxxxxx are queue-4.14/random-remove-kernel.random.read_wakeup_threshold.patch queue-4.14/random-initialize-chacha20-constants-with-correct-endianness.patch queue-4.14/random-make-dev-random-be-almost-like-dev-urandom.patch queue-4.14/random-remove-batched-entropy-locking.patch queue-4.14/random-remove-the-blocking-pool.patch queue-4.14/random-ignore-grnd_random-in-getentropy-2.patch queue-4.14/random-delete-code-to-pull-data-into-pools.patch queue-4.14/random-don-t-wake-crng_init_wait-when-crng_init-1.patch queue-4.14/random-add-a-urandom_read_nowait-for-random-apis-that-don-t-warn.patch queue-4.14/random-remove-dead-code-left-over-from-blocking-pool.patch queue-4.14/random-try-to-actively-add-entropy-rather-than-passively-wait-for-it.patch queue-4.14/random-add-grnd_insecure-to-return-best-effort-non-cryptographic-bytes.patch