From: Andy Lutomirski Date: Mon, 23 Dec 2019 08:20:45 +0000 (-0800) Subject: random: Add a urandom_read_nowait() for random APIs that don't warn X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=c6f1deb158789abba02a7eba600747843eeb3a57;p=openwrt%2Fstaging%2Fblogic.git random: Add a urandom_read_nowait() for random APIs that don't warn /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 Link: https://lore.kernel.org/r/c87ab200588de746431d9f916501ef11e5242b13.1577088521.git.luto@kernel.org Signed-off-by: Theodore Ts'o --- diff --git a/drivers/char/random.c b/drivers/char/random.c index 502e37141c72..91954c0091a5 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -2019,12 +2019,23 @@ 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--; @@ -2036,10 +2047,8 @@ 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 @@ -2201,7 +2210,7 @@ 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); } /********************************************************************