When multiple wireless USB devices are connected and one of the devices
disconnects, the host will distribute a new group key to the remaining
devicese using wusbhc_gtk_rekey. wusbhc_gtk_rekey takes the
wusbhc->mutex and holds it while it submits a URB to set the new key.
This causes a deadlock in wa_urb_enqueue when it calls a device lookup
helper function that takes the same lock.
This patch changes wusbhc_gtk_rekey to submit a work item to set the GTK
so that the URB is submitted without holding wusbhc->mutex.
Signed-off-by: Thomas Pugliese <thomas.pugliese@xxxxxxxxx>
---
drivers/usb/wusbcore/devconnect.c | 24 +--------
drivers/usb/wusbcore/security.c | 98 +++++++++++++++++++++----------------
drivers/usb/wusbcore/wusbhc.h | 6 +--
include/linux/usb/wusb.h | 2 +
4 files changed, 62 insertions(+), 68 deletions(-)
diff --git a/drivers/usb/wusbcore/devconnect.c b/drivers/usb/wusbcore/devconnect.c
index 5107ca9..f14e792 100644
--- a/drivers/usb/wusbcore/devconnect.c
+++ b/drivers/usb/wusbcore/devconnect.c
@@ -97,18 +97,12 @@ static void wusbhc_devconnect_acked_work(struct work_struct *work);
static void wusb_dev_free(struct wusb_dev *wusb_dev)
{
- if (wusb_dev) {
- kfree(wusb_dev->set_gtk_req);
- usb_free_urb(wusb_dev->set_gtk_urb);
- kfree(wusb_dev);
- }
+ kfree(wusb_dev);
}
static struct wusb_dev *wusb_dev_alloc(struct wusbhc *wusbhc)
{
struct wusb_dev *wusb_dev;
- struct urb *urb;
- struct usb_ctrlrequest *req;
wusb_dev = kzalloc(sizeof(*wusb_dev), GFP_KERNEL);
if (wusb_dev == NULL)
@@ -118,22 +112,6 @@ static struct wusb_dev *wusb_dev_alloc(struct wusbhc *wusbhc)
INIT_WORK(&wusb_dev->devconnect_acked_work, wusbhc_devconnect_acked_work);
- urb = usb_alloc_urb(0, GFP_KERNEL);
- if (urb == NULL)
- goto err;
- wusb_dev->set_gtk_urb = urb;
-
- req = kmalloc(sizeof(*req), GFP_KERNEL);
- if (req == NULL)
- goto err;
- wusb_dev->set_gtk_req = req;
-
- req->bRequestType = USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE;
- req->bRequest = USB_REQ_SET_DESCRIPTOR;
- req->wValue = cpu_to_le16(USB_DT_KEY << 8 | wusbhc->gtk_index);
- req->wIndex = 0;
- req->wLength = cpu_to_le16(wusbhc->gtk.descr.bLength);
-
return wusb_dev;
err:
wusb_dev_free(wusb_dev);
diff --git a/drivers/usb/wusbcore/security.c b/drivers/usb/wusbcore/security.c
index dd88441..4c40d0d 100644
--- a/drivers/usb/wusbcore/security.c
+++ b/drivers/usb/wusbcore/security.c
@@ -29,19 +29,16 @@
#include <linux/export.h>
#include "wusbhc.h"
-static void wusbhc_set_gtk_callback(struct urb *urb);
-static void wusbhc_gtk_rekey_done_work(struct work_struct *work);
+static void wusbhc_gtk_rekey_work(struct work_struct *work);
int wusbhc_sec_create(struct wusbhc *wusbhc)
{
wusbhc->gtk.descr.bLength = sizeof(wusbhc->gtk.descr) + sizeof(wusbhc->gtk.data);
wusbhc->gtk.descr.bDescriptorType = USB_DT_KEY;
wusbhc->gtk.descr.bReserved = 0;
+ wusbhc->gtk_index = 0;
- wusbhc->gtk_index = wusb_key_index(0, WUSB_KEY_INDEX_TYPE_GTK,
- WUSB_KEY_INDEX_ORIGINATOR_HOST);
-
- INIT_WORK(&wusbhc->gtk_rekey_done_work, wusbhc_gtk_rekey_done_work);
+ INIT_WORK(&wusbhc->gtk_rekey_work, wusbhc_gtk_rekey_work);
return 0;
}
@@ -113,7 +110,7 @@ int wusbhc_sec_start(struct wusbhc *wusbhc)
wusbhc_generate_gtk(wusbhc);
result = wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid,
- &wusbhc->gtk.descr.bKeyData, key_size);
+ &wusbhc->gtk.descr.bKeyData, key_size);
if (result < 0)
dev_err(wusbhc->dev, "cannot set GTK for the host: %d\n",
result);
@@ -129,7 +126,7 @@ int wusbhc_sec_start(struct wusbhc *wusbhc)
*/
void wusbhc_sec_stop(struct wusbhc *wusbhc)
{
- cancel_work_sync(&wusbhc->gtk_rekey_done_work);
+ cancel_work_sync(&wusbhc->gtk_rekey_work);
}
@@ -185,12 +182,14 @@ static int wusb_dev_set_encryption(struct usb_device *usb_dev, int value)
static int wusb_dev_set_gtk(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
{
struct usb_device *usb_dev = wusb_dev->usb_dev;
+ u8 key_index = wusb_key_index(wusbhc->gtk_index,
+ WUSB_KEY_INDEX_TYPE_GTK, WUSB_KEY_INDEX_ORIGINATOR_HOST);
return usb_control_msg(
usb_dev, usb_sndctrlpipe(usb_dev, 0),
USB_REQ_SET_DESCRIPTOR,
USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
- USB_DT_KEY << 8 | wusbhc->gtk_index, 0,
+ USB_DT_KEY << 8 | key_index, 0,
&wusbhc->gtk.descr, wusbhc->gtk.descr.bLength,
1000);
}
@@ -520,24 +519,55 @@ error_kzalloc:
* Once all connected and authenticated devices have received the new
* GTK, switch the host to using it.
*/
-static void wusbhc_gtk_rekey_done_work(struct work_struct *work)
+static void wusbhc_gtk_rekey_work(struct work_struct *work)
{
- struct wusbhc *wusbhc = container_of(work, struct wusbhc, gtk_rekey_done_work);
+ struct wusbhc *wusbhc = container_of(work,
+ struct wusbhc, gtk_rekey_work);
size_t key_size = sizeof(wusbhc->gtk.data);
+ int port_idx;
+ struct wusb_dev *wusb_dev, *wusb_dev_next;
+ LIST_HEAD(rekey_list);
mutex_lock(&wusbhc->mutex);
+ /* generate the new key */
+ wusbhc_generate_gtk(wusbhc);
+ /* roll the gtk index. */
+ wusbhc->gtk_index = (wusbhc->gtk_index + 1) % (WUSB_KEY_INDEX_MAX + 1);
+ /*
+ * Save all connected devices on a list while holding wusbhc->mutex and
+ * take a reference to each one. Then submit the set key request to
+ * them after releasing the lock in order to avoid a deadlock.
+ */
+ for (port_idx = 0; port_idx < wusbhc->ports_max; port_idx++) {
+ wusb_dev = wusbhc->port[port_idx].wusb_dev;
+ if (!wusb_dev || !wusb_dev->usb_dev
+ || !wusb_dev->usb_dev->authenticated)
+ continue;
- if (--wusbhc->pending_set_gtks == 0)
- wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid, &wusbhc->gtk.descr.bKeyData, key_size);
-
+ wusb_dev_get(wusb_dev);
+ list_add_tail(&wusb_dev->rekey_node, &rekey_list);
+ }
mutex_unlock(&wusbhc->mutex);
-}
-static void wusbhc_set_gtk_callback(struct urb *urb)
-{
- struct wusbhc *wusbhc = urb->context;
+ /* Submit the rekey requests without holding wusbhc->mutex. */
+ list_for_each_entry_safe(wusb_dev, wusb_dev_next, &rekey_list,
+ rekey_node) {
+ list_del_init(&wusb_dev->rekey_node);
+ dev_dbg(&wusb_dev->usb_dev->dev, "%s: rekey device at port %d\n",
+ __func__, wusb_dev->port_idx);
+
+ if (wusb_dev_set_gtk(wusbhc, wusb_dev) < 0) {
+ dev_err(&wusb_dev->usb_dev->dev, "%s: rekey device at port %d failed\n",
+ __func__, wusb_dev->port_idx);
+ }
+ wusb_dev_put(wusb_dev);
+ }
- queue_work(wusbd, &wusbhc->gtk_rekey_done_work);
+ /* Switch the host controller to use the new GTK. */
+ mutex_lock(&wusbhc->mutex);
+ wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid,
+ &wusbhc->gtk.descr.bKeyData, key_size);
+ mutex_unlock(&wusbhc->mutex);
}
/**
@@ -553,26 +583,12 @@ static void wusbhc_set_gtk_callback(struct urb *urb)
*/
void wusbhc_gtk_rekey(struct wusbhc *wusbhc)
{
- static const size_t key_size = sizeof(wusbhc->gtk.data);
- int p;
-
- wusbhc_generate_gtk(wusbhc);
-
- for (p = 0; p < wusbhc->ports_max; p++) {
- struct wusb_dev *wusb_dev;
-
- wusb_dev = wusbhc->port[p].wusb_dev;
- if (!wusb_dev || !wusb_dev->usb_dev || !wusb_dev->usb_dev->authenticated)
- continue;
-
- usb_fill_control_urb(wusb_dev->set_gtk_urb, wusb_dev->usb_dev,
- usb_sndctrlpipe(wusb_dev->usb_dev, 0),
- (void *)wusb_dev->set_gtk_req,
- &wusbhc->gtk.descr, wusbhc->gtk.descr.bLength,
- wusbhc_set_gtk_callback, wusbhc);
- if (usb_submit_urb(wusb_dev->set_gtk_urb, GFP_KERNEL) == 0)
- wusbhc->pending_set_gtks++;
- }
- if (wusbhc->pending_set_gtks == 0)
- wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid, &wusbhc->gtk.descr.bKeyData, key_size);
+ /*
+ * We need to submit a URB to the downstream WUSB devices in order to
+ * change the group key. This can't be done while holding the
+ * wusbhc->mutex since that is also taken in the urb_enqueue routine
+ * and will cause a deadlock. Instead, queue a work item to do
+ * it when the lock is not held
+ */
+ queue_work(wusbd, &wusbhc->gtk_rekey_work);
}
diff --git a/drivers/usb/wusbcore/wusbhc.h b/drivers/usb/wusbcore/wusbhc.h
index 711b195..6bd3b81 100644
--- a/drivers/usb/wusbcore/wusbhc.h
+++ b/drivers/usb/wusbcore/wusbhc.h
@@ -97,6 +97,7 @@ struct wusb_dev {
struct kref refcnt;
struct wusbhc *wusbhc;
struct list_head cack_node; /* Connect-Ack list */
+ struct list_head rekey_node; /* GTK rekey list */
u8 port_idx;
u8 addr;
u8 beacon_type:4;
@@ -107,8 +108,6 @@ struct wusb_dev {
struct usb_wireless_cap_descriptor *wusb_cap_descr;
struct uwb_mas_bm availability;
struct work_struct devconnect_acked_work;
- struct urb *set_gtk_urb;
- struct usb_ctrlrequest *set_gtk_req;
struct usb_device *usb_dev;
};
@@ -296,8 +295,7 @@ struct wusbhc {
} __attribute__((packed)) gtk;
u8 gtk_index;
u32 gtk_tkid;
- struct work_struct gtk_rekey_done_work;
- int pending_set_gtks;
+ struct work_struct gtk_rekey_work;
struct usb_encryption_descriptor *ccm1_etd;
};
diff --git a/include/linux/usb/wusb.h b/include/linux/usb/wusb.h
index 0c4d4ca..eeb2832 100644
--- a/include/linux/usb/wusb.h
+++ b/include/linux/usb/wusb.h
@@ -271,6 +271,8 @@ static inline u8 wusb_key_index(int index, int type, int originator)
#define WUSB_KEY_INDEX_TYPE_GTK 2
#define WUSB_KEY_INDEX_ORIGINATOR_HOST 0
#define WUSB_KEY_INDEX_ORIGINATOR_DEVICE 1
+/* bits 0-3 used for the key index. */
+#define WUSB_KEY_INDEX_MAX 15
/* A CCM Nonce, defined in WUSB1.0[6.4.1] */
struct aes_ccm_nonce {
--
1.7.10.4
--
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