From 471e42ad148c05d091219096726d751684ebf918 Mon Sep 17 00:00:00 2001 From: Thomas Pugliese Date: Mon, 2 Dec 2013 15:39:45 -0600 Subject: [PATCH] usb: wusbcore: fix deadlock in wusbhc_gtk_rekey 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 Signed-off-by: Greg Kroah-Hartman --- 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 5107ca999d4c..f14e7929ba22 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 dd88441c8f78..4c40d0dbf53d 100644 --- a/drivers/usb/wusbcore/security.c +++ b/drivers/usb/wusbcore/security.c @@ -29,19 +29,16 @@ #include #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 711b1952b114..6bd3b819a6b5 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 0c4d4ca370ec..eeb28329fa3c 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 { -- 2.20.1