wifi: cfg80211: Avoid clashing function prototypes

When built with Control Flow Integrity, function prototypes between
caller and function declaration must match. These mismatches are visible
at compile time with the new -Wcast-function-type-strict in Clang[1].

Fix a total of 73 warnings like these:

drivers/net/wireless/intersil/orinoco/wext.c:1379:27: warning: cast from 'int (*)(struct net_device *, struct iw_request_info *, struct iw_param *, char *)' to 'iw_handler' (aka 'int (*)(struct net_device *, struct iw_request_info *, union iwreq_data *, char *)') converts to incompatible function type [-Wcast-function-type-strict]
IW_HANDLER(SIOCGIWPOWER, (iw_handler)orinoco_ioctl_getpower),
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

../net/wireless/wext-compat.c:1607:33: warning: cast from 'int (*)(struct net_device *, struct iw_request_info *, struct iw_point *, char *)' to 'iw_handler' (aka 'int (*)(struct net_device *, struct iw_request_info *, union iwreq_data *, char *)') converts to incompatible function type [-Wcast-function-type-strict]
[IW_IOCTL_IDX(SIOCSIWGENIE)] = (iw_handler) cfg80211_wext_siwgenie,
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

../drivers/net/wireless/intersil/orinoco/wext.c:1390:27: error: incompatible function pointer types initializing 'const iw_handler' (aka 'int (*const)(struct net_device *, struct iw_request_info *, union iwreq_data *, char *)') with an expression of type 'int (struct net_device *, struct iw_request_info *, struct iw_param *, char *)' [-Wincompatible-function-pointer-types]
IW_HANDLER(SIOCGIWRETRY, cfg80211_wext_giwretry),
^~~~~~~~~~~~~~~~~~~~~~

The cfg80211 Wireless Extension handler callbacks (iw_handler) use a
union for the data argument. Actually use the union and perform explicit
member selection in the function body instead of having a function
prototype mismatch. There are no resulting binary differences
before/after changes.

These changes were made partly manually and partly with the help of
Coccinelle.

Link: https://github.com/KSPP/linux/issues/234
Link: https://reviews.llvm.org/D134831 [1]
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/a68822bf8dd587988131bb6a295280cb4293f05d.1667934775.git.gustavoars@kernel.org

treewide: Add SPDX license identifier for missed files

Add SPDX license identifiers to all files which:

- Have no license information of any form

- Have EXPORT_.*_SYMBOL_GPL inside which was used in the
initial scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

cfg80211-wext: export symbols only when needed

When a fully converted cfg80211 driver needs cfg80211-wext for
userspace API purposes, the symbols need not be exported. When
other drivers (orinoco/hermes or ipw2200) are enabled, they do
need the symbols exported as they use them directly.

Make those drivers select a new CFG80211_WEXT_EXPORT Kconfig
symbol (instead of just CFG80211_WEXT) and export the functions
only if requested - this saves about 1/2k due to the size of
EXPORT_SYMBOL() itself.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

cfg80211: remove unused wiphy argument from cfg80211_wext_freq()

cfg80211_wext_freq() is declared in wext-compat.h, but its
parameter struct wiphy's declaration is not included there.
As the parameter isn't used, just remove it.

Signed-off-by: Zhao, Gang <gamerh2o@gmail.com>
[remove parameter instead of changing to netdev]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

cfg80211: remove unused wext handler exports

A lot of code is dedicated to giving drivers the
ability to use cfg80211's wext handlers without
completely converting. However, only orinoco is
currently using this, and it is only partially
using it.

We reduce the size of both the source and binary
by removing those that nobody needs. If a driver
shows up that needs it during conversion, we can
add back those that are needed.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

cfg80211: validate channel settings across interfaces

Currently, there's a problem that affects regulatory
enforcement and connection stability, in that it is
possible to switch the channel while connected to a
network or joined to an IBSS.

The problem comes from the fact that we only validate
the channel against the current interface's type, not
against any other interface. Thus, you have any type
of interface up, additionally bring up a monitor mode
interface and switch the channel on the monitor. This
will obviously also switch the channel on the other
interface.

The problem now is that if you do that while sending
beacons for IBSS mode, you can switch to a disabled
channel or a channel that doesn't allow beaconing.
Combined with a managed mode interface connected to
an AP instead of an IBSS interface, you can easily
break the connection that way.

To fix this, this patch validates any channel change
with all available interfaces, and disallows such
changes on secondary interfaces if another interface
is connected to an AP or joined to an IBSS.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

cfg80211: self-contained wext handling where possible

Finally! This is what you've all been waiting for!

This patch makes cfg80211 take care of wext emulation
_completely_ by itself, drivers that don't need things
cfg80211 doesn't do yet don't even need to be aware of
wireless extensions.
This means we can also clean up mac80211's and iwm's
Kconfig and make it possible to build them w/o wext
now!

RIP wext.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

cfg80211: combine IWESSID handlers

Since we now have handlers IWESSID for all modes, we can
combine them into one.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

cfg80211: combine IWAP handlers

Since we now have IWAP handlers for all modes, we can
combine them into one.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

cfg80211: combine iwfreq implementations

Until now we implemented iwfreq for managed mode, we
needed to keep the implementations separate, but now
that we have all versions implemented we can combine
them and export just one handler.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>