[PATCH v3 2/8] random: Add a urandom_read_nowait() for random APIs that don't warn
From: Andy Lutomirski <luto@kernel.org>
Date: 2019-12-23 08:21:42
Also in:
linux-ext4, linux-man, lkml
Subsystem:
random number driver, the rest · Maintainers:
"Theodore Ts'o", Jason A. Donenfeld, Linus Torvalds
/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: Andy Lutomirski <luto@kernel.org> --- drivers/char/random.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index c6252a3a4aec..7b46751772e5 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c@@ -2018,12 +2018,23 @@ 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--;
@@ -2035,10 +2046,8 @@ 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
@@ -2200,7 +2209,7 @@ 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); } /********************************************************************
--
2.23.0