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[src/trunk]: src/sys/netbt When encrypted connections are configured, verify ...
details: https://anonhg.NetBSD.org/src/rev/5a5066bec737
branches: trunk
changeset: 459842:5a5066bec737
user: plunky <plunky%NetBSD.org@localhost>
date: Sat Sep 28 07:06:33 2019 +0000
description:
When encrypted connections are configured, verify that the encryption
key length has a minimum size when the adaptor supports that.
This addresses the 'Key Negotiation of Bluetooth' attack, CVE-2019-9506
https://www.bluetooth.com/security/statement-key-negotiation-of-bluetooth/
diffstat:
sys/netbt/hci.h | 15 ++++++-
sys/netbt/hci_event.c | 105 ++++++++++++++++++++++++++++++++++++++++----------
2 files changed, 97 insertions(+), 23 deletions(-)
diffs (214 lines):
diff -r 1f66e485b65f -r 5a5066bec737 sys/netbt/hci.h
--- a/sys/netbt/hci.h Sat Sep 28 07:06:32 2019 +0000
+++ b/sys/netbt/hci.h Sat Sep 28 07:06:33 2019 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: hci.h,v 1.45 2018/07/25 19:09:38 kamil Exp $ */
+/* $NetBSD: hci.h,v 1.46 2019/09/28 07:06:33 plunky Exp $ */
/*-
* Copyright (c) 2005 Iain Hibbert.
@@ -54,7 +54,7 @@
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
- * $Id: hci.h,v 1.45 2018/07/25 19:09:38 kamil Exp $
+ * $Id: hci.h,v 1.46 2019/09/28 07:06:33 plunky Exp $
* $FreeBSD: src/sys/netgraph/bluetooth/include/ng_hci.h,v 1.6 2005/01/07 01:45:43 imp Exp $
*/
@@ -1812,6 +1812,17 @@
uint16_t accuracy; /* clock accuracy */
} __packed hci_read_clock_rp;
+#define HCI_OCF_READ_ENCRYPTION_KEY_SIZE 0x0008
+#define HCI_CMD_READ_ENCRYPTION_KEY_SIZE 0x1408
+typedef struct {
+ uint16_t con_handle; /* connection handle */
+} __packed hci_read_encryption_key_size_cp;
+
+typedef struct {
+ uint8_t status; /* 0x00 - success */
+ uint16_t con_handle; /* connection handle */
+ uint8_t size; /* key size */
+} __packed hci_read_encryption_key_size_rp;
/**************************************************************************
**************************************************************************
diff -r 1f66e485b65f -r 5a5066bec737 sys/netbt/hci_event.c
--- a/sys/netbt/hci_event.c Sat Sep 28 07:06:32 2019 +0000
+++ b/sys/netbt/hci_event.c Sat Sep 28 07:06:33 2019 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: hci_event.c,v 1.25 2018/08/21 14:59:13 plunky Exp $ */
+/* $NetBSD: hci_event.c,v 1.26 2019/09/28 07:06:33 plunky Exp $ */
/*-
* Copyright (c) 2005 Iain Hibbert.
@@ -31,7 +31,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: hci_event.c,v 1.25 2018/08/21 14:59:13 plunky Exp $");
+__KERNEL_RCSID(0, "$NetBSD: hci_event.c,v 1.26 2019/09/28 07:06:33 plunky Exp $");
#include <sys/param.h>
#include <sys/kernel.h>
@@ -63,6 +63,7 @@
static void hci_cmd_read_local_extended_features(struct hci_unit *, struct mbuf *);
static void hci_cmd_read_local_ver(struct hci_unit *, struct mbuf *);
static void hci_cmd_read_local_commands(struct hci_unit *, struct mbuf *);
+static void hci_cmd_read_encryption_key_size(struct hci_unit *, struct mbuf *);
static void hci_cmd_reset(struct hci_unit *, struct mbuf *);
static void hci_cmd_create_con(struct hci_unit *unit, uint8_t status);
@@ -353,6 +354,10 @@
hci_cmd_read_local_commands(unit, m);
break;
+ case HCI_CMD_READ_ENCRYPTION_KEY_SIZE:
+ hci_cmd_read_encryption_key_size(unit, m);
+ break;
+
case HCI_CMD_RESET:
hci_cmd_reset(unit, m);
break;
@@ -623,10 +628,11 @@
return;
}
- /* XXX could check auth_enable here */
-
- if (ep.encryption_mode)
- link->hl_flags |= (HCI_LINK_AUTH | HCI_LINK_ENCRYPT);
+ /*
+ * We purposefully ignore ep.encryption_mode here - if that is set then
+ * the link will be authenticated and encrypted, but we still want to
+ * verify the key size and setmode sets the right flags
+ */
link->hl_state = HCI_LINK_OPEN;
link->hl_handle = HCI_CON_HANDLE(le16toh(ep.con_handle));
@@ -777,17 +783,16 @@
/*
* Encryption Change
*
- * The encryption status has changed. Basically, we note the change
- * then notify the upper layer protocol unless further mode changes
- * are pending.
- * Note that if encryption gets disabled when it has been requested,
- * we will attempt to enable it again.. (its a feature not a bug :)
+ * The encryption status has changed. Make a note if disabled, or
+ * check the key size if possible before allowing it is enabled.
+ * (checking of key size was enabled in 3.0 spec)
*/
static void
hci_event_encryption_change(struct hci_unit *unit, struct mbuf *m)
{
hci_encryption_change_ep ep;
struct hci_link *link;
+ uint16_t con_handle;
int err;
if (m->m_pkthdr.len < sizeof(ep))
@@ -796,27 +801,34 @@
m_copydata(m, 0, sizeof(ep), &ep);
m_adj(m, sizeof(ep));
- ep.con_handle = HCI_CON_HANDLE(le16toh(ep.con_handle));
+ con_handle = HCI_CON_HANDLE(le16toh(ep.con_handle));
DPRINTFN(1, "handle #%d, status=0x%x, encryption_enable=0x%x\n",
- ep.con_handle, ep.status, ep.encryption_enable);
+ con_handle, ep.status, ep.encryption_enable);
- link = hci_link_lookup_handle(unit, ep.con_handle);
+ link = hci_link_lookup_handle(unit, con_handle);
if (link == NULL || link->hl_type != HCI_LINK_ACL)
return;
if (ep.status == 0) {
- if (ep.encryption_enable == 0)
+ if (ep.encryption_enable == 0) {
link->hl_flags &= ~HCI_LINK_ENCRYPT;
- else
+ } else if (unit->hci_cmds[20] & (1<<4)) {
+ err = hci_send_cmd(unit, HCI_CMD_READ_ENCRYPTION_KEY_SIZE,
+ &ep.con_handle, sizeof(ep.con_handle));
+
+ if (err == 0)
+ return;
+ } else {
link->hl_flags |= (HCI_LINK_AUTH | HCI_LINK_ENCRYPT);
- if (link->hl_state == HCI_LINK_WAIT_ENCRYPT)
- link->hl_state = HCI_LINK_OPEN;
+ if (link->hl_state == HCI_LINK_WAIT_ENCRYPT)
+ link->hl_state = HCI_LINK_OPEN;
- err = hci_acl_setmode(link);
- if (err == EINPROGRESS)
- return;
+ err = hci_acl_setmode(link);
+ if (err == EINPROGRESS)
+ return;
+ }
}
hci_acl_linkmode(link);
@@ -1175,6 +1187,57 @@
}
/*
+ * process results of read_encryption_key_size command_complete event
+ */
+static void
+hci_cmd_read_encryption_key_size(struct hci_unit *unit, struct mbuf *m)
+{
+ hci_read_encryption_key_size_rp rp;
+ struct hci_link *link;
+ int err;
+
+ if (m->m_pkthdr.len < sizeof(rp))
+ return;
+
+ m_copydata(m, 0, sizeof(rp), &rp);
+ m_adj(m, sizeof(rp));
+
+ if (rp.status != 0)
+ return;
+
+ rp.con_handle = HCI_CON_HANDLE(le16toh(rp.con_handle));
+
+ DPRINTFN(1, "handle #%d, status=0x%x, key_size=0x%x\n",
+ rp.con_handle, rp.status, rp.size);
+
+ link = hci_link_lookup_handle(unit, rp.con_handle);
+ if (link == NULL || link->hl_type != HCI_LINK_ACL)
+ return;
+
+ /*
+ * if the key size is less than minimum standard, go straight to
+ * linkmode as this is non-recoverable. Otherwise, we are encrypted
+ * so can proceed with setmode.
+ */
+ if (rp.status == 0) {
+ if (rp.size < 7) {
+ link->hl_flags &= ~HCI_LINK_ENCRYPT;
+ } else {
+ link->hl_flags |= (HCI_LINK_AUTH | HCI_LINK_ENCRYPT);
+
+ if (link->hl_state == HCI_LINK_WAIT_ENCRYPT)
+ link->hl_state = HCI_LINK_OPEN;
+
+ err = hci_acl_setmode(link);
+ if (err == EINPROGRESS)
+ return;
+ }
+ }
+
+ hci_acl_linkmode(link);
+}
+
+/*
* process results of reset command_complete event
*
* This has killed all the connections, so close down anything we have left,
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