Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted

Pull I3C updates from Alexandre Belloni:
 "A new driver this cycle, for the AMD AXI I3C controller.

  There are also new features such as IBI wakeup support, SETAASA device
  discovery and ACPI support for the the DAA methods, meaning we can now
  communicate with the SPD devices on DDR5 modules.

  New driver:
   - AMD AXI I3C master controller

  Subsystem:
   - I3C Common Command Code (CCC) handling improvements, especially
     around GET CCCs
   - SETAASA device discovery support
   - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as
     well as I2C devices on I3C bus
   - IBI-based wakeup support

  Drivers:
   - dw: SETAASA support
   - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C
     controller support, PIO queue management support for HCI v1.2
   - renesas: improve suspend to RAM support, add runtime PM support"

* tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits)
  i3c: dw: reduce do_daa time if there's no client
  i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller
  i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2
  i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode
  i3c: dw: rename "pclk" to "apb" to match dt-binding
  i3c: dw: make struct dw_i3c_cmd smaller
  i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding
  i3c: renesas: Don't register devices when ENTDAA times out
  i3c: master: dw-i3c-master: fix OD timing for first broadcast
  i3c: mipi-i3c-hci: Advertise IBI wakeup capability
  i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev()
  i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI
  i3c: master: Reject IBI requests from non-IBI-capable devices
  i3c: master: Add helper to query bus wakeup requirements
  i3c: master: Report wakeup events for IBIs
  i3c: master: Support IBI-based wakeup capability
  i3c: master: Fix potential UAF in i3c_device_match()
  i3c: master: Fix potential UAF in i3c_device_uevent()
  i3c: Make dev->desc locking assumptions explicit
  i3c: master: Fix use-after-free of master->this
  ...

1 files changed, 129 insertions, 0 deletions

diff --git a/Documentation/usb/authorization.rst b/Documentation/usb/authorization.rst
new file mode 100644
index 000000000..150a14970
--- /dev/null
+++ b/Documentation/usb/authorization.rst
@@ -0,0 +1,129 @@
+==============================================================
+Authorizing (or not) your USB devices to connect to the system
+==============================================================
+
+Copyright (C) 2007 Inaky Perez-Gonzalez <inaky@linux.intel.com> Intel Corporation
+
+This feature allows you to control if a USB device can be used (or
+not) in a system. This feature will allow you to implement a lock-down
+of USB devices, fully controlled by user space.
+
+As of now, when a USB device is connected it is configured and
+its interfaces are immediately made available to the users.  With this
+modification, only if root authorizes the device to be configured will
+then it be possible to use it.
+
+Usage
+=====
+
+Authorize a device to connect::
+
+	$ echo 1 > /sys/bus/usb/devices/DEVICE/authorized
+
+De-authorize a device::
+
+	$ echo 0 > /sys/bus/usb/devices/DEVICE/authorized
+
+Set new devices connected to hostX to be deauthorized by default (ie:
+lock down)::
+
+	$ echo 0 > /sys/bus/usb/devices/usbX/authorized_default
+
+Remove the lock down::
+
+	$ echo 1 > /sys/bus/usb/devices/usbX/authorized_default
+
+By default, all USB devices are authorized.  Writing "2" to the
+authorized_default attribute causes the kernel to authorize by default
+only devices connected to internal USB ports.
+
+
+Example system lockdown (lame)
+------------------------------
+
+Imagine you want to implement a lockdown so only devices of type XYZ
+can be connected (for example, it is a kiosk machine with a visible
+USB port)::
+
+  boot up
+  rc.local ->
+
+   for host in /sys/bus/usb/devices/usb*
+   do
+      echo 0 > $host/authorized_default
+   done
+
+Hookup an script to udev, for new USB devices::
+
+ if device_is_my_type $DEV
+ then
+   echo 1 > $device_path/authorized
+ done
+
+
+Now, device_is_my_type() is where the juice for a lockdown is. Just
+checking if the class, type and protocol match something is the worse
+security verification you can make (or the best, for someone willing
+to break it). If you need something secure, use crypto and Certificate
+Authentication or stuff like that. Something simple for an storage key
+could be::
+
+ function device_is_my_type()
+ {
+   echo 1 > authorized		# temporarily authorize it
+                                # FIXME: make sure none can mount it
+   mount DEVICENODE /mntpoint
+   sum=$(md5sum /mntpoint/.signature)
+   if [ $sum = $(cat /etc/lockdown/keysum) ]
+   then
+        echo "We are good, connected"
+        umount /mntpoint
+        # Other stuff so others can use it
+   else
+        echo 0 > authorized
+   fi
+ }
+
+
+Of course, this is lame, you'd want to do a real certificate
+verification stuff with PKI, so you don't depend on a shared secret,
+etc, but you get the idea. Anybody with access to a device gadget kit
+can fake descriptors and device info. Don't trust that. You are
+welcome.
+
+
+Interface authorization
+-----------------------
+
+There is a similar approach to allow or deny specific USB interfaces.
+That allows to block only a subset of an USB device.
+
+Authorize an interface::
+
+	$ echo 1 > /sys/bus/usb/devices/INTERFACE/authorized
+
+Deauthorize an interface::
+
+	$ echo 0 > /sys/bus/usb/devices/INTERFACE/authorized
+
+The default value for new interfaces
+on a particular USB bus can be changed, too.
+
+Allow interfaces per default::
+
+	$ echo 1 > /sys/bus/usb/devices/usbX/interface_authorized_default
+
+Deny interfaces per default::
+
+	$ echo 0 > /sys/bus/usb/devices/usbX/interface_authorized_default
+
+Per default the interface_authorized_default bit is 1.
+So all interfaces would authorized per default.
+
+Note:
+  If a deauthorized interface will be authorized so the driver probing must
+  be triggered manually by writing INTERFACE to /sys/bus/usb/drivers_probe
+
+For drivers that need multiple interfaces all needed interfaces should be
+authorized first. After that the drivers should be probed.
+This avoids side effects.