From: Andy Lutomirski luto@kernel.org
commit 75551dbf112c992bc6c99a972990b3f272247e23 upstream.
Signed-off-by: Andy Lutomirski luto@kernel.org Link: https://lore.kernel.org/r/d5473b56cf1fa900ca4bd2b3fc1e5b8874399919.157708852... Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 */