[PATCH] USB: disable all RNDIS protocol drivers

Greg Kroah-Hartman
2022-11-23T13:09:38Z

The Microsoft RNDIS protocol is, as designed, insecure and vulnerable on
any system that uses it with untrusted hosts or devices. Because the
protocol is impossible to make secure, just disable all rndis drivers to
prevent anyone from using them again.

Windows only needed this for XP and newer systems, Windows systems older
than that can use the normal USB class protocols instead, which do not
have these problems.

Android has had this disabled for many years so there should not be any
real systems that still need this.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Kalle Valo <kvalo@kernel.org>
Cc: Oleksij Rempel <linux@rempel-privat.de>
Cc: "Maciej Żenczykowski" <maze@google.com>
Cc: Neil Armstrong <neil.armstrong@linaro.org>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Andrzej Pietrasiewicz <andrzejtp2010@gmail.com>
Cc: Jacopo Mondi <jacopo@jmondi.org>
Cc: "Łukasz Stelmach" <l.stelmach@samsung.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: linux-usb@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-wireless@vger.kernel.org
Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
Reported-by: Joseph Tartaro <joseph.tartaro@ioactive.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
Note, I'll submit patches removing the individual drivers for later, but
that is more complex as unwinding the interaction between the CDC
networking and RNDIS drivers is tricky. For now, let's just disable all
of this code as it is not secure.

I can take this through the USB tree if the networking maintainers have
no objection. I thought I had done this months ago, when the last round
of "there are bugs in the protocol!" reports happened at the end of
2021, but forgot to do so, my fault.

drivers/net/usb/Kconfig | 1 +
drivers/net/wireless/Kconfig | 1 +
drivers/usb/gadget/Kconfig | 4 +---
drivers/usb/gadget/legacy/Kconfig | 3 +++
4 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/usb/Kconfig b/drivers/net/usb/Kconfig
index 4402eedb3d1a..83f9c0632642 100644
--- a/drivers/net/usb/Kconfig
+++ b/drivers/net/usb/Kconfig
@@ -401,6 +401,7 @@ config USB_NET_MCS7830
config USB_NET_RNDIS_HOST
tristate "Host for RNDIS and ActiveSync devices"
depends on USB_USBNET
+ depends on BROKEN
select USB_NET_CDCETHER
help
This option enables hosting "Remote NDIS" USB networking links,
diff --git a/drivers/net/wireless/Kconfig b/drivers/net/wireless/Kconfig
index cb1c15012dd0..f162b25123d7 100644
--- a/drivers/net/wireless/Kconfig
+++ b/drivers/net/wireless/Kconfig
@@ -81,6 +81,7 @@ config USB_NET_RNDIS_WLAN
tristate "Wireless RNDIS USB support"
depends on USB
depends on CFG80211
+ depends on BROKEN
select USB_NET_DRIVERS
select USB_USBNET
select USB_NET_CDCETHER
diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index 4fa2ddf322b4..2c99d4313064 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -183,9 +183,6 @@ config USB_F_EEM
config USB_F_SUBSET
tristate

-config USB_F_RNDIS
- tristate
-
config USB_F_MASS_STORAGE
tristate

@@ -297,6 +294,7 @@ config USB_CONFIGFS_RNDIS
bool "RNDIS"
depends on USB_CONFIGFS
depends on NET
+ depends on BROKEN
select USB_U_ETHER
select USB_F_RNDIS
help
diff --git a/drivers/usb/gadget/legacy/Kconfig b/drivers/usb/gadget/legacy/Kconfig
index 0a7b382fbe27..03d6da63edf7 100644
--- a/drivers/usb/gadget/legacy/Kconfig
+++ b/drivers/usb/gadget/legacy/Kconfig
@@ -153,6 +153,7 @@ config USB_ETH
config USB_ETH_RNDIS
bool "RNDIS support"
depends on USB_ETH
+ depends on BROKEN
select USB_LIBCOMPOSITE
select USB_F_RNDIS
default y
@@ -247,6 +248,7 @@ config USB_FUNCTIONFS_ETH
config USB_FUNCTIONFS_RNDIS
bool "Include configuration with RNDIS (Ethernet)"
depends on USB_FUNCTIONFS && NET
+ depends on BROKEN
select USB_U_ETHER
select USB_F_RNDIS
help
@@ -427,6 +429,7 @@ config USB_G_MULTI
config USB_G_MULTI_RNDIS
bool "RNDIS + CDC Serial + Storage configuration"
depends on USB_G_MULTI
+ depends on BROKEN
select USB_F_RNDIS
default y
help
--
2.38.1