linux-kernel - [PATCH v3 4/8] random: Ignore GRND

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Date:   Mon, 23 Dec 2019 00:20:47 -0800
From:   Andy Lutomirski <luto@...nel.org>
To:     Ted Ts'o <tytso@....edu>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Linux API <linux-api@...r.kernel.org>,
        Kees Cook <keescook@...omium.org>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        "Ahmed S. Darwish" <darwish.07@...il.com>,
        Lennart Poettering <mzxreary@...inter.de>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        "Alexander E. Patrakov" <patrakov@...il.com>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Willy Tarreau <w@....eu>,
        Matthew Garrett <mjg59@...f.ucam.org>,
        Ext4 Developers List <linux-ext4@...r.kernel.org>,
        linux-man <linux-man@...r.kernel.org>,
        Stephan Mueller <smueller@...onox.de>,
        Andy Lutomirski <luto@...nel.org>
Subject: [PATCH v3 4/8] random: Ignore GRND_RANDOM in getentropy(2)

The separate blocking pool is going away.  Start by ignoring
GRND_RANDOM in getentropy(2).

This should not materially break any API.  Any code that worked
without this change should work at least as well with this change.

Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
 drivers/char/random.c       | 3 ---
 include/uapi/linux/random.h | 2 +-
 2 files changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 675b8a48e18a..c0a3032b30ca 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -2206,9 +2206,6 @@ SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
 	if (count > INT_MAX)
 		count = INT_MAX;
 
-	if (flags & GRND_RANDOM)
-		return _random_read(flags & GRND_NONBLOCK, buf, count);
-
 	if (!(flags & GRND_INSECURE) && !crng_ready()) {
 		if (flags & GRND_NONBLOCK)
 			return -EAGAIN;
diff --git a/include/uapi/linux/random.h b/include/uapi/linux/random.h
index c092d20088d3..dcc1b3e6106f 100644
--- a/include/uapi/linux/random.h
+++ b/include/uapi/linux/random.h
@@ -48,7 +48,7 @@ struct rand_pool_info {
  * Flags for getrandom(2)
  *
  * GRND_NONBLOCK	Don't block and return EAGAIN instead
- * GRND_RANDOM		Use the /dev/random pool instead of /dev/urandom
+ * GRND_RANDOM		No effect
  * GRND_INSECURE	Return non-cryptographic random bytes
  */
 #define GRND_NONBLOCK	0x0001
-- 
2.23.0