treewide: uapi: Replace zero-length arrays with flexible-array members

There is a regular need in the kernel to provide a way to declare
having a dynamically sized set of trailing elements in a structure.
Kernel code should always use “flexible array members”[1] for these
cases. The older style of one-element or zero-length arrays should
no longer be used[2].

This code was transformed with the help of Coccinelle:
(linux-5.19-rc2$ spatch --jobs $(getconf _NPROCESSORS_ONLN) --sp-file script.cocci --include-headers --dir . > output.patch)

@@
identifier S, member, array;
type T1, T2;
@@

struct S {
...
T1 member;
T2 array[
- 0
];
};

-fstrict-flex-arrays=3 is coming and we need to land these changes
to prevent issues like these in the short future:

../fs/minix/dir.c:337:3: warning: 'strcpy' will always overflow; destination buffer has size 0,
but the source string has length 2 (including NUL byte) [-Wfortify-source]
strcpy(de3->name, ".");
^

Since these are all [0] to [] changes, the risk to UAPI is nearly zero. If
this breaks anything, we can use a union with a new member name.

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/78
Build-tested-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/62b675ec.wKX6AOZ6cbE71vtF%25lkp@intel.com/
Acked-by: Dan Williams <dan.j.williams@intel.com> # For ndctl.h
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

USB: usbfs: Add a capability flag for runtime suspend

The recent commit 7794f486ed0b ("usbfs: Add ioctls for runtime power
management") neglected to add a corresponding capability flag. This
patch rectifies the omission.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Mayuresh Kulkarni <mkulkarni@opensource.cirrus.com>

Link: https://lore.kernel.org/r/Pine.LNX.4.44L0.1908131613490.1941-100000@iolanthe.rowland.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usbfs: Add ioctls for runtime power management

It has been requested that usbfs should implement runtime power
management, instead of forcing the device to remain at full power as
long as the device file is open. This patch introduces that new
feature.

It does so by adding three new usbfs ioctls:

USBDEVFS_FORBID_SUSPEND: Prevents the device from going into
runtime suspend (and causes a resume if the device is already
suspended).

USBDEVFS_ALLOW_SUSPEND: Allows the device to go into runtime
suspend. Some time may elapse before the device actually is
suspended, depending on things like the autosuspend delay.

USBDEVFS_WAIT_FOR_RESUME: Blocks until the call is interrupted
by a signal or at least one runtime resume has occurred since
the most recent ALLOW_SUSPEND ioctl call (which may mean
immediately, even if the device is currently suspended). In
the latter case, the device is prevented from suspending again
just as if FORBID_SUSPEND was called before the ioctl returns.

For backward compatibility, when the device file is first opened
runtime suspends are forbidden. The userspace program can then allow
suspends whenever it wants, and either resume the device directly (by
forbidding suspends again) or wait for a resume from some other source
(such as a remote wakeup). URBs submitted to a suspended device will
fail or will complete with an appropriate error code.

This combination of ioctls is sufficient for user programs to have
nearly the same degree of control over a device's runtime power
behavior as kernel drivers do.

Still lacking is documentation for the new ioctls. I intend to add it
later, after the existing documentation for the usbfs userspace API is
straightened out into a reasonable form.

Suggested-by: Mayuresh Kulkarni <mkulkarni@opensource.cirrus.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>

Link: https://lore.kernel.org/r/Pine.LNX.4.44L0.1908071013220.1514-100000@iolanthe.rowland.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

USB: fix types in uapi include

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

USB: add usbfs ioctl to retrieve the connection parameters

Recently usfbs gained availability to retrieve device speed, but there
is sill no way to determine the bus number or list of ports the device
is connected to when using usbfs. While this information can be obtained
from sysfs, not all environments allow sysfs access. In a jailed
environment a program might be simply given an opened file descriptor to
usbfs device, and it is really important that all data can be gathered
from said file descriptor.

This patch introduces a new ioctl, USBDEVFS_CONNINFO_EX, which return
extended connection information for the device, including the bus
number, address, port list and speed. The API allows kernel to extend
amount of data returned by the ioctl and userspace has an option of
adjusting the amount of data it is willing to consume. A new capability,
USBDEVFS_CAP_CONNINFO_EX, is introduced to help userspace in determining
whether the kernel supports this new ioctl.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

USB: remove the URB_NO_FSBR flag

The URB_NO_FSBR flag has never really been used. It was introduced as
a potential way for UHCI to minimize PCI bus usage (by not attempting
full-speed bulk and control transfers more than once per frame), but
the flag was not set by any drivers.

There's no point in keeping it around. This patch simplifies the API
by removing it. Unfortunately, it does have to be kept as part of the
usbfs ABI, but at least we can document in
include/uapi/linux/usbdevice_fs.h that it doesn't do anything.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

License cleanup: add SPDX license identifier to uapi header files with a license

Many user space API headers have licensing information, which is either
incomplete, badly formatted or just a shorthand for referring to the
license under which the file is supposed to be. This makes it hard for
compliance tools to determine the correct license.

Update these files with an SPDX license identifier. The identifier was
chosen based on the license information in the file.

GPL/LGPL licensed headers get the matching GPL/LGPL SPDX license
identifier with the added 'WITH Linux-syscall-note' exception, which is
the officially assigned exception identifier for the kernel syscall
exception:

NOTE! This copyright does *not* cover user programs that use kernel
services by normal system calls - this is merely considered normal use
of the kernel, and does *not* fall under the heading of "derived work".

This exception makes it possible to include GPL headers into non GPL
code, without confusing license compliance tools.

Headers which have either explicit dual licensing or are just licensed
under a non GPL license are updated with the corresponding SPDX
identifier and the GPLv2 with syscall exception identifier. The format
is:
((GPL-2.0 WITH Linux-syscall-note) OR SPDX-ID-OF-OTHER-LICENSE)

SPDX license identifiers are a legally binding shorthand, which can be
used instead of the full boiler plate text. The update does not remove
existing license information as this has to be done on a case by case
basis and the copyright holders might have to be consulted. This will
happen in a separate step.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne. See the previous patch in this series for the
methodology of how this patch was researched.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

USB: add usbfs ioctl to retrieve the connection speed

The usbfs interface does not provide any way for the user to learn the
speed at which a device is connected. The current API includes a
USBDEVFS_CONNECTINFO ioctl, but all it provides is the device's
address and a one-bit value indicating whether the connection is low
speed. That may have sufficed in the era of USB-1.1, but it isn't
good enough today.

This patch introduces a new ioctl, USBDEVFS_GET_SPEED, which returns a
numeric value indicating the speed of the connection: unknown, low,
full, high, wireless, super, or super-plus.

Similar information (not exactly the same) is available through sysfs,
but it seems reasonable to provide the actual value in usbfs.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Reinhard Huck <reinhard.huck@thesycon.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: devio: Add ioctl to disallow detaching kernel USB drivers.

The new USBDEVFS_DROP_PRIVILEGES ioctl allows a process to voluntarily
relinquish the ability to issue other ioctls that may interfere with
other processes and drivers that have claimed an interface on the
device.

This commit also includes a simple utility to be able to test the
ioctl, located at Documentation/usb/usbdevfs-drop-permissions.c

Example (with qemu-kvm's input device):

$ lsusb
...
Bus 001 Device 002: ID 0627:0001 Adomax Technology Co., Ltd

$ usb-devices
...
C: #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr=100mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=03(HID ) Sub=00 Prot=02 Driver=usbhid

$ sudo ./usbdevfs-drop-permissions /dev/bus/usb/001/002
OK: privileges dropped!
Available options:
[0] Exit now
[1] Reset device. Should fail if device is in use
[2] Claim 4 interfaces. Should succeed where not in use
[3] Narrow interface permission mask
Which option shall I run?: 1
ERROR: USBDEVFS_RESET failed! (1 - Operation not permitted)
Which test shall I run next?: 2
ERROR claiming if 0 (1 - Operation not permitted)
ERROR claiming if 1 (1 - Operation not permitted)
ERROR claiming if 2 (1 - Operation not permitted)
ERROR claiming if 3 (1 - Operation not permitted)
Which test shall I run next?: 0

After unbinding usbhid:

$ usb-devices
...
I: If#= 0 Alt= 0 #EPs= 1 Cls=03(HID ) Sub=00 Prot=02 Driver=(none)

$ sudo ./usbdevfs-drop-permissions /dev/bus/usb/001/002
...
Which option shall I run?: 2
OK: claimed if 0
ERROR claiming if 1 (1 - Operation not permitted)
ERROR claiming if 2 (1 - Operation not permitted)
ERROR claiming if 3 (1 - Operation not permitted)
Which test shall I run next?: 1
OK: USBDEVFS_RESET succeeded
Which test shall I run next?: 0

After unbinding usbhid and restricting the mask:

$ sudo ./usbdevfs-drop-permissions /dev/bus/usb/001/002
...
Which option shall I run?: 3
Insert new mask: 0
OK: privileges dropped!
Which test shall I run next?: 2
ERROR claiming if 0 (1 - Operation not permitted)
ERROR claiming if 1 (1 - Operation not permitted)
ERROR claiming if 2 (1 - Operation not permitted)
ERROR claiming if 3 (1 - Operation not permitted)

Signed-off-by: Reilly Grant <reillyg@chromium.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Emilio López <emilio.lopez@collabora.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

USB: Add support for usbfs zerocopy.

Add a new interface for userspace to preallocate memory that can be
used with usbfs. This gives two primary benefits:

- Zerocopy; data no longer needs to be copied between the userspace
and the kernel, but can instead be read directly by the driver from
userspace's buffers. This works for all kinds of transfers (even if
nonsensical for control and interrupt transfers); isochronous also
no longer need to memset() the buffer to zero to avoid leaking kernel data.

- Once the buffers are allocated, USB transfers can no longer fail due to
memory fragmentation; previously, long-running programs could run into
problems finding a large enough contiguous memory chunk, especially on
embedded systems or at high rates.

Memory is allocated by using mmap() against the usbfs file descriptor,
and similarly deallocated by munmap(). Once memory has been allocated,
using it as pointers to a bulk or isochronous operation means you will
automatically get zerocopy behavior. Note that this also means you cannot
modify outgoing data until the transfer is complete. The same holds for
data on the same cache lines as incoming data; DMA modifying them at the
same time could lead to your changes being overwritten.

There's a new capability USBDEVFS_CAP_MMAP that userspace can query to see
if the running kernel supports this functionality, if just trying mmap() is
not acceptable.

Largely based on a patch by Markus Rechberger with some updates. The original
patch can be found at:

http://sundtek.de/support/devio_mmap_v0.4.diff

Signed-off-by: Steinar H. Gunderson <sesse@google.com>
Signed-off-by: Markus Rechberger <mrechberger@gmail.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

USB: usbfs: allow URBs to be reaped after disconnection

The usbfs API has a peculiar hole: Users are not allowed to reap their
URBs after the device has been disconnected. There doesn't seem to be
any good reason for this; it is an ad-hoc inconsistency.

The patch allows users to issue the USBDEVFS_REAPURB and
USBDEVFS_REAPURBNDELAY ioctls (together with their 32-bit counterparts
on 64-bit systems) even after the device is gone. If no URBs are
pending for a disconnected device then the ioctls will return -ENODEV
rather than -EAGAIN, because obviously no new URBs will ever be able
to complete.

The patch also adds a new capability flag for
USBDEVFS_GET_CAPABILITIES to indicate that the reap-after-disconnect
feature is supported.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Chris Dickens <christopher.a.dickens@gmail.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

usbfs: Add support for allocating / freeing streams

This allows userspace to use bulk-streams, just like in kernel drivers, see
Documentation/usb/bulk-streams.txt for details on the in kernel API. This
is exported pretty much one on one to userspace.

To use streams an app must first make a USBDEVFS_ALLOC_STREAMS ioctl,
on success this will return the number of streams available (which may be
less then requested). If there are n streams the app can then submit
usbdevfs_urb-s with their stream_id member set to 1-n to use a specific
stream. IE if USBDEVFS_ALLOC_STREAMS returns 4 then stream_id 1-4 can be
used.

When the app is done using streams it should call USBDEVFS_FREE_STREAMS

Note applications are advised to use libusb rather then using the
usbdevfs api directly. The latest version of libusb has support for streams.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

usbfs: Add support for bulk stream ids

This patch makes it possible to specify a bulk stream id when submitting
an urb using the async usbfs API. It overloads the number_of_packets
usbdevfs_urb field for this. This is not pretty, but given other
constraints it is the best we can do. The reasoning leading to this goes
as follows:

1) We want to support bulk streams in the usbfs API
2) We do not want to extend the usbdevfs_urb struct with a new member, as
that would mean defining new ioctl numbers for all async API ioctls +
adding compat versions for the old ones (times 2 for 32 bit support)
3) 1 + 2 means we need to re-use an existing field
4) number_of_packets is only used for isoc urbs, and streams are bulk only
so it is the best (and only) candidate for re-using

Note that:
1) This patch only uses number_of_packets as stream_id if the app has
actually allocated streams on the ep, so that old apps which may have
garbage in there (as it was unused until now in the bulk case), will not
break
2) This patch does not add support for allocating / freeing bulk-streams, that
is done in a follow up patch

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

UAPI: (Scripted) Disintegrate include/linux

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>