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

2 files changed, 5 insertions, 2 deletions

diff --git a/sys/arch/macppc/conf/GENERIC b/sys/arch/macppc/conf/GENERIC
index f6d3812cede..67020e6df45 100644
--- a/sys/arch/macppc/conf/GENERIC
+++ b/sys/arch/macppc/conf/GENERIC
@@ -1,4 +1,4 @@
-#	$OpenBSD: GENERIC,v 1.268 2019/05/08 23:54:39 kettenis Exp $g
+#	$OpenBSD: GENERIC,v 1.269 2019/12/17 13:08:56 reyk Exp $g
 #
 # For further information on compiling OpenBSD kernels, see the config(8)
 # man page.
@@ -261,6 +261,7 @@ 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
diff --git a/sys/arch/macppc/macppc/conf.c b/sys/arch/macppc/macppc/conf.c
index 97491cbf275..061a11e9a2e 100644
--- a/sys/arch/macppc/macppc/conf.c
+++ b/sys/arch/macppc/macppc/conf.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: conf.c,v 1.68 2019/09/03 17:51:52 deraadt Exp $ */
+/*	$OpenBSD: conf.c,v 1.69 2019/12/17 13:08:56 reyk Exp $ */
 
 /*
  * Copyright (c) 1997 Per Fogelstrom
@@ -96,6 +96,7 @@ cdev_decl(com);
 #include "ksyms.h"
 #include "usb.h"
 #include "uhid.h"
+#include "fido.h"
 #include "ugen.h"
 #include "ulpt.h"
 #include "ucom.h"
@@ -226,6 +227,7 @@ struct cdevsw cdevsw[] = {
 	cdev_drm_init(NDRM,drm),	/* 87: drm */
 	cdev_fuse_init(NFUSE,fuse),	/* 88: fuse */
 	cdev_switch_init(NSWITCH,switch), /* 89: switch(4) control interface */
+	cdev_fido_init(NFIDO,fido),	/* 90: FIDO/U2F security key */
 };
 int nchrdev = nitems(cdevsw);