[SRU][F/aws][PATCH 3/5] random: Add a urandom_read_nowait() for random APIs that don't warn
Andrea Righi
andrea.righi at canonical.com
Fri May 7 08:15:45 UTC 2021
From: Andy Lutomirski <luto at kernel.org>
BugLink: https://bugs.launchpad.net/bugs/1927692
/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 at kernel.org>
Link: https://lore.kernel.org/r/c87ab200588de746431d9f916501ef11e5242b13.1577088521.git.luto@kernel.org
Signed-off-by: Theodore Ts'o <tytso at mit.edu>
(cherry picked from commit c6f1deb158789abba02a7eba600747843eeb3a57)
Signed-off-by: Andrea Righi <andrea.righi at canonical.com>
---
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 3089aee11a7e..cfa87fcfe51b 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
@@ -2206,7 +2215,7 @@ 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);
}
/********************************************************************
--
2.30.2
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