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From: Andy Lutomirski <luto@kernel.org>
To: Ted Ts'o <tytso@mit.edu>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Linux API <linux-api@vger.kernel.org>,
	Kees Cook <keescook@chromium.org>,
	"Jason A. Donenfeld" <Jason@zx2c4.com>,
	"Ahmed S. Darwish" <darwish.07@gmail.com>,
	Lennart Poettering <mzxreary@0pointer.de>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	"Alexander E. Patrakov" <patrakov@gmail.com>,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	Willy Tarreau <w@1wt.eu>, Matthew Garrett <mjg59@srcf.ucam.org>,
	Ext4 Developers List <linux-ext4@vger.kernel.org>,
	linux-man <linux-man@vger.kernel.org>,
	Stephan Mueller <smueller@chronox.de>,
	Andy Lutomirski <luto@kernel.org>
Subject: [PATCH v3 2/8] random: Add a urandom_read_nowait() for random APIs that don't warn
Date: Mon, 23 Dec 2019 00:20:45 -0800
Message-ID: <c87ab200588de746431d9f916501ef11e5242b13.1577088521.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1577088521.git.luto@kernel.org>

/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


  parent reply index

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-23  8:20 [PATCH v3 0/8] Rework random blocking Andy Lutomirski
2019-12-23  8:20 ` [PATCH v3 1/8] random: Don't wake crng_init_wait when crng_init == 1 Andy Lutomirski
2020-01-07 20:42   ` Theodore Y. Ts'o
2019-12-23  8:20 ` Andy Lutomirski [this message]
2020-01-07 20:43   ` [PATCH v3 2/8] random: Add a urandom_read_nowait() for random APIs that don't warn Theodore Y. Ts'o
2019-12-23  8:20 ` [PATCH v3 3/8] random: Add GRND_INSECURE to return best-effort non-cryptographic bytes Andy Lutomirski
2020-01-07 20:44   ` Theodore Y. Ts'o
2019-12-23  8:20 ` [PATCH v3 4/8] random: Ignore GRND_RANDOM in getentropy(2) Andy Lutomirski
2020-01-07 20:44   ` Theodore Y. Ts'o
2019-12-23  8:20 ` [PATCH v3 5/8] random: Make /dev/random be almost like /dev/urandom Andy Lutomirski
2020-01-07 21:02   ` Theodore Y. Ts'o
2019-12-23  8:20 ` [PATCH v3 6/8] random: Remove the blocking pool Andy Lutomirski
2020-01-07 21:03   ` Theodore Y. Ts'o
2019-12-23  8:20 ` [PATCH v3 7/8] random: Delete code to pull data into pools Andy Lutomirski
2020-01-07 21:03   ` Theodore Y. Ts'o
2019-12-23  8:20 ` [PATCH v3 8/8] random: Remove kernel.random.read_wakeup_threshold Andy Lutomirski
2020-01-07 21:04   ` Theodore Y. Ts'o
2019-12-26  9:29 ` [PATCH v3 0/8] Rework random blocking Stephan Müller
2019-12-26 10:03   ` Matthew Garrett
2019-12-26 11:40     ` Stephan Mueller
2019-12-26 11:12   ` Andy Lutomirski
2019-12-26 12:03     ` Stephan Mueller
2019-12-26 12:46       ` Andy Lutomirski
2019-12-27  9:55         ` Stephan Mueller
2019-12-26 14:04       ` Theodore Y. Ts'o
2019-12-26 23:29         ` Andy Lutomirski
2019-12-27 10:29           ` Stephan Mueller
2019-12-27 13:04             ` Theodore Y. Ts'o
2019-12-27 21:22               ` Stephan Mueller
2019-12-27 22:08                 ` Theodore Y. Ts'o
2019-12-28  2:06                   ` Andy Lutomirski
2019-12-29 14:49                     ` Theodore Y. Ts'o
2019-12-29 15:08                       ` Andy Lutomirski
2019-12-28  7:01                   ` Willy Tarreau
2020-01-09 22:02                   ` Kurt Roeckx
2020-01-09 22:40                     ` Theodore Y. Ts'o
2020-01-09 23:02                       ` Kurt Roeckx
2020-01-10  7:53                         ` Stephan Mueller
2020-01-10  0:30                     ` Andy Lutomirski

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