Add fido(4), a HID driver for FIDO/U2F security keys

While FIDO/U2F keys were already supported by the generic uhid(4)
driver, this driver adds the first step to tighten the security of
FIDO/U2F access.  Specifically, users don't need read/write access to
all USB/HID devices anymore and the driver also improves integration
with pledge(2) and unveil(2): It is pledge-friendly because it doesn't
require any ioctls to discover the device and unveil-friendly because
it uses a single /dev/fido/* directory for its device nodes.

It also allows to support FIDO/U2F in firefox without further
weakening the "sandbox" of the browser.  Firefox does not have a
proper privsep design and many operations, such as U2F access, are
handled directly by the main process.  This means that the browser's
"fat" main process needs direct read/write access to all USB HID
devices, at least on other operating systems.  With fido(4) we can
support security keys in Firefox under OpenBSD without such a
compromise.

With this change, libfido2 stops using the ioctl to query the device
vendor/product and just assumes "OpenBSD" "fido(4)" instead.  The
ioctl is still supported but there was no benefit in obtaining the
vendor product or name; it also allows to use libfido2 under pledge.

With feedback from deraadt@ and many others
OK kettenis@ djm@ and jmc@ for the manpage bits

1 files changed, 2 insertions, 1 deletions

diff --git a/sys/arch/landisk/conf/GENERIC b/sys/arch/landisk/conf/GENERIC
index fb4aa07244f..0c59680830a 100644
--- a/sys/arch/landisk/conf/GENERIC
+++ b/sys/arch/landisk/conf/GENERIC
@@ -1,4 +1,4 @@
-# $OpenBSD: GENERIC,v 1.54 2019/05/08 23:54:39 kettenis Exp $
+# $OpenBSD: GENERIC,v 1.55 2019/12/17 13:08:55 reyk Exp $
 #
 # For further information on compiling OpenBSD kernels, see the config(8)
 # man page.
@@ -136,6 +136,7 @@ ucom*	at ucycom?
 uslhcom* at uhidev?		# Silicon Labs CP2110 USB HID UART
 ucom*	at uslhcom?
 uhid*	at uhidev?		# USB generic HID support
+fido*	at uhidev?		# FIDO/U2F security key support
 upd*	at uhidev?		# USB Power Devices sensors
 aue*	at uhub?		# ADMtek AN986 Pegasus Ethernet
 atu*	at uhub?		# Atmel AT76c50x based 802.11b