linux-kernel - [PATCH 1/2] hwrng: don't fetch rng from sources without init

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <c911b7944f2d05f5c6f5cf5dc37b8dbb99fd0b14.1404296679.git.amit.shah@redhat.com>
Date:	Wed,  2 Jul 2014 15:58:15 +0530
From:	Amit Shah <amit.shah@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	Virtualization List <virtualization@...ts.linux-foundation.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	herbert@...dor.apana.org.au, keescook@...omium.org,
	jason@...edaemon.net, Amit Shah <amit.shah@...hat.com>,
	<stable@...r.kernel.org>
Subject: [PATCH 1/2] hwrng: don't fetch rng from sources without init

Commit d9e7972619334 "hwrng: add randomness to system from rng sources"
added a call to rng_get_data() from the hwrng_register() function.
However, some rng devices need initialization before data can be read
from them.

Also, the virtio-rng device does not behave properly when this call is
made in its probe() routine - the virtio core sets the DRIVER_OK status
bit only on a successful probe, which means the host ignores all
communication from the guest, and the guest insmod or boot process just
sits there doing nothing.

This commit makes the call to rng_get_data() depend on no init fn
pointer being registered by the device.  If an init function is
registered, this call isn't made.

CC: Kees Cook <keescook@...omium.org>
CC: Jason Cooper <jason@...edaemon.net>
CC: Herbert Xu <herbert@...dor.apana.org.au>
CC: <stable@...r.kernel.org> # For 3.15 only
Signed-off-by: Amit Shah <amit.shah@...hat.com>
---
 drivers/char/hw_random/core.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index 334601c..3f3941d 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -347,9 +347,11 @@ int hwrng_register(struct hwrng *rng)
 	INIT_LIST_HEAD(&rng->list);
 	list_add_tail(&rng->list, &rng_list);
 
-	bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1);
-	if (bytes_read > 0)
-		add_device_randomness(bytes, bytes_read);
+	if (!rng->init) {
+		bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1);
+		if (bytes_read > 0)
+			add_device_randomness(bytes, bytes_read);
+	}
 out_unlock:
 	mutex_unlock(&rng_mutex);
 out:
-- 
1.9.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/