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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 08/11] usb: Add USB subsystem notifications [ver #7] From: David Howells To: viro@zeniv.linux.org.uk Cc: dhowells@redhat.com, Casey Schaufler , Stephen Smalley , Greg Kroah-Hartman , nicolas.dichtel@6wind.com, raven@themaw.net, Christian Brauner , dhowells@redhat.com, keyrings@vger.kernel.org, linux-usb@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-block@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Date: Fri, 30 Aug 2019 14:58:23 +0100 Message-ID: <156717350329.2204.7056537095039252263.stgit@warthog.procyon.org.uk> In-Reply-To: <156717343223.2204.15875738850129174524.stgit@warthog.procyon.org.uk> References: <156717343223.2204.15875738850129174524.stgit@warthog.procyon.org.uk> User-Agent: StGit/unknown-version MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.40]); Fri, 30 Aug 2019 13:58:26 +0000 (UTC) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: Add a USB subsystem notification mechanism whereby notifications about hardware events such as device connection, disconnection, reset and I/O errors, can be reported to a monitoring process asynchronously. Firstly, an event queue needs to be created: fd = open("/dev/event_queue", O_RDWR); ioctl(fd, IOC_WATCH_QUEUE_SET_SIZE, page_size << n); then a notification can be set up to report USB notifications via that queue: struct watch_notification_filter filter = { .nr_filters = 1, .filters = { [0] = { .type = WATCH_TYPE_USB_NOTIFY, .subtype_filter[0] = UINT_MAX; }, }, }; ioctl(fd, IOC_WATCH_QUEUE_SET_FILTER, &filter); notify_devices(fd, 12); After that, records will be placed into the queue when events occur on a USB device or bus. Records are of the following format: struct usb_notification { struct watch_notification watch; __u32 error; __u32 reserved; __u8 name_len; __u8 name[0]; } *n; Where: n->watch.type will be WATCH_TYPE_USB_NOTIFY n->watch.subtype will be the type of notification, such as NOTIFY_USB_DEVICE_ADD. n->watch.info & WATCH_INFO_LENGTH will indicate the length of the record. n->watch.info & WATCH_INFO_ID will be the second argument to device_notify(), shifted. n->error and n->reserved are intended to convey information such as error codes, but are currently not used n->name_len and n->name convey the USB device name as an unterminated string. This may be truncated - it is currently limited to a maximum 63 chars. Note that it is permissible for event records to be of variable length - or, at least, the length may be dependent on the subtype. Signed-off-by: David Howells Reviewed-by: Greg Kroah-Hartman cc: linux-usb@vger.kernel.org --- Documentation/watch_queue.rst | 9 ++++++ drivers/usb/core/Kconfig | 9 ++++++ drivers/usb/core/devio.c | 56 ++++++++++++++++++++++++++++++++++++++ drivers/usb/core/hub.c | 4 +++ include/linux/usb.h | 18 ++++++++++++ include/uapi/linux/watch_queue.h | 30 ++++++++++++++++++++ 6 files changed, 125 insertions(+), 1 deletion(-) diff --git a/Documentation/watch_queue.rst b/Documentation/watch_queue.rst index 5cc9c6924727..4087a8e670a8 100644 --- a/Documentation/watch_queue.rst +++ b/Documentation/watch_queue.rst @@ -11,6 +11,8 @@ receive notifications from the kernel. This can be used in conjunction with:: * Block layer event notifications + * USB subsystem event notifications + The notifications buffers can be enabled by: @@ -315,6 +317,13 @@ Any particular buffer can be fed from multiple sources. Sources include: or temporary link loss. Watches of this type are set on the global device watch list. + * WATCH_TYPE_USB_NOTIFY + + Notifications of this type indicate USB subsystem events, such as + attachment, removal, reset and I/O errors. Separate events are generated + for buses and devices. Watchpoints of this type are set on the global + device watch list. + Event Filtering =============== diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig index ecaacc8ed311..57e7b649e48b 100644 --- a/drivers/usb/core/Kconfig +++ b/drivers/usb/core/Kconfig @@ -102,3 +102,12 @@ config USB_AUTOSUSPEND_DELAY The default value Linux has always had is 2 seconds. Change this value if you want a different delay and cannot modify the command line or module parameter. + +config USB_NOTIFICATIONS + bool "Provide USB hardware event notifications" + depends on USB && DEVICE_NOTIFICATIONS + help + This option provides support for getting hardware event notifications + on USB devices and interfaces. This makes use of the + /dev/watch_queue misc device to handle the notification buffer. + device_notify(2) is used to set/remove watches. diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index 9063ede411ae..b8572e4d6a1b 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -41,6 +41,7 @@ #include #include #include +#include #include "usb.h" @@ -2660,13 +2661,68 @@ static void usbdev_remove(struct usb_device *udev) } } +#ifdef CONFIG_USB_NOTIFICATIONS +static noinline void post_usb_notification(const char *devname, + enum usb_notification_type subtype, + u32 error) +{ + unsigned int gran = WATCH_LENGTH_GRANULARITY; + unsigned int name_len, n_len; + u64 id = 0; /* Might want to put a dev# here. */ + + struct { + struct usb_notification n; + char more_name[USB_NOTIFICATION_MAX_NAME_LEN - + (sizeof(struct usb_notification) - + offsetof(struct usb_notification, name))]; + } n; + + name_len = strlen(devname); + name_len = min_t(size_t, name_len, USB_NOTIFICATION_MAX_NAME_LEN); + n_len = round_up(offsetof(struct usb_notification, name) + name_len, + gran) / gran; + + memset(&n, 0, sizeof(n)); + memcpy(n.n.name, devname, n_len); + + n.n.watch.type = WATCH_TYPE_USB_NOTIFY; + n.n.watch.subtype = subtype; + n.n.watch.info = n_len; + n.n.error = error; + n.n.name_len = name_len; + + post_device_notification(&n.n.watch, id); +} + +void post_usb_device_notification(const struct usb_device *udev, + enum usb_notification_type subtype, u32 error) +{ + post_usb_notification(dev_name(&udev->dev), subtype, error); +} + +void post_usb_bus_notification(const struct usb_bus *ubus, + enum usb_notification_type subtype, u32 error) +{ + post_usb_notification(ubus->bus_name, subtype, error); +} +#endif + static int usbdev_notify(struct notifier_block *self, unsigned long action, void *dev) { switch (action) { case USB_DEVICE_ADD: + post_usb_device_notification(dev, NOTIFY_USB_DEVICE_ADD, 0); break; case USB_DEVICE_REMOVE: + post_usb_device_notification(dev, NOTIFY_USB_DEVICE_REMOVE, 0); + usbdev_remove(dev); + break; + case USB_BUS_ADD: + post_usb_bus_notification(dev, NOTIFY_USB_BUS_ADD, 0); + break; + case USB_BUS_REMOVE: + post_usb_bus_notification(dev, NOTIFY_USB_BUS_REMOVE, 0); usbdev_remove(dev); break; } diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 236313f41f4a..e8ebacc15a32 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -29,6 +29,7 @@ #include #include #include +#include #include #include @@ -4605,6 +4606,9 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1, (udev->config) ? "reset" : "new", speed, devnum, driver_name); + if (udev->config) + post_usb_device_notification(udev, NOTIFY_USB_DEVICE_RESET, 0); + /* Set up TT records, if needed */ if (hdev->tt) { udev->tt = hdev->tt; diff --git a/include/linux/usb.h b/include/linux/usb.h index e87826e23d59..ddfb9dc2473e 100644 --- a/include/linux/usb.h +++ b/include/linux/usb.h @@ -26,6 +26,7 @@ struct usb_device; struct usb_driver; struct wusb_dev; +enum usb_notification_type; /*-------------------------------------------------------------------------*/ @@ -2010,6 +2011,23 @@ extern void usb_led_activity(enum usb_led_event ev); static inline void usb_led_activity(enum usb_led_event ev) {} #endif +/* + * Notification functions. + */ +#ifdef CONFIG_USB_NOTIFICATIONS +extern void post_usb_device_notification(const struct usb_device *udev, + enum usb_notification_type subtype, + u32 error); +extern void post_usb_bus_notification(const struct usb_bus *ubus, + enum usb_notification_type subtype, + u32 error); +#else +static inline void post_usb_device_notification(const struct usb_device *udev, + unsigned int subtype, u32 error) {} +static inline void post_usb_bus_notification(const struct usb_bus *ubus, + unsigned int subtype, u32 error) {} +#endif + #endif /* __KERNEL__ */ #endif diff --git a/include/uapi/linux/watch_queue.h b/include/uapi/linux/watch_queue.h index 9a6c059af09d..bc5183e10d8c 100644 --- a/include/uapi/linux/watch_queue.h +++ b/include/uapi/linux/watch_queue.h @@ -12,7 +12,8 @@ enum watch_notification_type { WATCH_TYPE_META = 0, /* Special record */ WATCH_TYPE_KEY_NOTIFY = 1, /* Key change event notification */ WATCH_TYPE_BLOCK_NOTIFY = 2, /* Block layer event notification */ - WATCH_TYPE___NR = 3 + WATCH_TYPE_USB_NOTIFY = 3, /* USB subsystem event notification */ + WATCH_TYPE___NR = 4 }; enum watch_meta_notification_subtype { @@ -152,4 +153,31 @@ struct block_notification { __u64 sector; /* Affected sector */ }; +/* + * Type of USB layer notification. + */ +enum usb_notification_type { + NOTIFY_USB_DEVICE_ADD = 0, /* USB device added */ + NOTIFY_USB_DEVICE_REMOVE = 1, /* USB device removed */ + NOTIFY_USB_BUS_ADD = 2, /* USB bus added */ + NOTIFY_USB_BUS_REMOVE = 3, /* USB bus removed */ + NOTIFY_USB_DEVICE_RESET = 4, /* USB device reset */ + NOTIFY_USB_DEVICE_ERROR = 5, /* USB device error */ +}; + +/* + * USB subsystem notification record. + * - watch.type = WATCH_TYPE_USB_NOTIFY + * - watch.subtype = enum usb_notification_type + */ +struct usb_notification { + struct watch_notification watch; /* WATCH_TYPE_USB_NOTIFY */ + __u32 error; + __u32 reserved; + __u8 name_len; /* Length of device name */ + __u8 name[0]; /* Device name (padded to __u64, truncated at 63 chars) */ +}; + +#define USB_NOTIFICATION_MAX_NAME_LEN 63 + #endif /* _UAPI_LINUX_WATCH_QUEUE_H */