This functionality allows a sufficiently privileged user-space process
to upload a BPF programme that will call to usb_revoke_device() as if
it were a kernel API.
This functionality will be used by logind to revoke access to devices on
fast user-switching to start with.
logind, and other session management software, does not have access to
the file descriptor used by the application so other identifiers
are used.
Signed-off-by: Bastien Nocera <hadess@xxxxxxxxxx>
---
drivers/usb/core/usb.c | 51 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 51 insertions(+)
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 2f71636af6e1..ca394848a51e 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -38,6 +38,8 @@
#include <linux/workqueue.h>
#include <linux/debugfs.h>
#include <linux/usb/of.h>
+#include <linux/btf.h>
+#include <linux/btf_ids.h>
#include <asm/io.h>
#include <linux/scatterlist.h>
@@ -438,6 +440,41 @@ static int usb_dev_uevent(struct device *dev, struct kobj_uevent_env *env)
return 0;
}
+struct usb_revoke_match {
+ int busnum, devnum; /* -1 to match all devices */
+ int euid; /* -1 to match all users */
+};
+
+static int
+__usb_revoke(struct usb_device *udev, void *data)
+{
+ struct usb_revoke_match *match = data;
+
+ if (match->devnum >= 0 && match->busnum >= 0) {
+ if (match->busnum != udev->bus->busnum ||
+ match->devnum != udev->devnum) {
+ return 0;
+ }
+ }
+
+ usb_revoke_for_euid(udev, match->euid);
+ return 0;
+}
+
+noinline int
+usb_revoke_device(int busnum, int devnum, unsigned int euid)
+{
+ struct usb_revoke_match match;
+
+ match.busnum = busnum;
+ match.devnum = devnum;
+ match.euid = euid;
+
+ usb_for_each_dev(&match, __usb_revoke);
+
+ return 0;
+}
+
#ifdef CONFIG_PM
/* USB device Power-Management thunks.
@@ -1004,6 +1041,15 @@ static void usb_debugfs_cleanup(void)
/*
* Init
*/
+BTF_SET_START(usbdev_kfunc_ids)
+BTF_ID(func, usb_revoke_device)
+BTF_SET_END(usbdev_kfunc_ids)
+
+static const struct btf_kfunc_id_set usbdev_kfunc_set = {
+ .owner = THIS_MODULE,
+ .check_set = &usbdev_kfunc_ids,
+};
+
static int __init usb_init(void)
{
int retval;
@@ -1035,9 +1081,14 @@ static int __init usb_init(void)
if (retval)
goto hub_init_failed;
retval = usb_register_device_driver(&usb_generic_driver, THIS_MODULE);
+ if (retval)
+ goto register_failed;
+ retval = register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, &usbdev_kfunc_set);
if (!retval)
goto out;
+ usb_deregister_device_driver(&usb_generic_driver);
+register_failed:
usb_hub_cleanup();
hub_init_failed:
usb_devio_cleanup();
--
2.37.1
