On Tue, Nov 17, 2020 at 12:59:02PM -0800, Sami Tolvanen wrote:
> Instead of casting callback functions to type iw_handler, which trips
> indirect call checking with Clang's Control-Flow Integrity (CFI), add
> stub functions with the correct function type for the callbacks.
Oh, wow. iw_handler with union iwreq_data look like really nasty hacks.
Aren't those just totally bypassing type checking? Where do the
callbacks actually happen? I couldn't find them...
>
> Reported-by: Sedat Dilek <sedat.dilek@xxxxxxxxx>
> Signed-off-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
> ---
> net/wireless/wext-compat.c | 103 +++++++++++++++++++++++++------------
> 1 file changed, 71 insertions(+), 32 deletions(-)
>
> diff --git a/net/wireless/wext-compat.c b/net/wireless/wext-compat.c
> index 78f2927ead7f..cf54c6e5b397 100644
> --- a/net/wireless/wext-compat.c
> +++ b/net/wireless/wext-compat.c
> @@ -1472,39 +1472,78 @@ static int cfg80211_wext_siwpmksa(struct net_device *dev,
> }
> }
>
> +#define DEFINE_WEXT_COMPAT_STUB(func, type) \
> + static int __ ## func(struct net_device *dev, \
> + struct iw_request_info *info, \
> + union iwreq_data *wrqu, \
> + char *extra) \
> + { \
> + return func(dev, info, (type *)wrqu, extra); \
> + }
> +
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_giwname, char)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_siwfreq, struct iw_freq)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_giwfreq, struct iw_freq)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_siwmode, u32)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_giwmode, u32)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_giwrange, struct iw_point)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_siwap, struct sockaddr)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_giwap, struct sockaddr)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_siwmlme, struct iw_point)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_giwscan, struct iw_point)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_siwessid, struct iw_point)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_giwessid, struct iw_point)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_siwrate, struct iw_param)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_giwrate, struct iw_param)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_siwrts, struct iw_param)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_giwrts, struct iw_param)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_siwfrag, struct iw_param)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_giwfrag, struct iw_param)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_siwretry, struct iw_param)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_giwretry, struct iw_param)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_siwencode, struct iw_point)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_giwencode, struct iw_point)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_giwpower, struct iw_param)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_siwpower, struct iw_param)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_siwgenie, struct iw_point)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_giwauth, struct iw_param)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_siwauth, struct iw_param)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_siwencodeext, struct iw_point)
> +DEFINE_WEXT_COMPAT_STUB(cfg80211_wext_siwpmksa, struct iw_point)
> +
> static const iw_handler cfg80211_handlers[] = {
> - [IW_IOCTL_IDX(SIOCGIWNAME)] = (iw_handler) cfg80211_wext_giwname,
> - [IW_IOCTL_IDX(SIOCSIWFREQ)] = (iw_handler) cfg80211_wext_siwfreq,
> - [IW_IOCTL_IDX(SIOCGIWFREQ)] = (iw_handler) cfg80211_wext_giwfreq,
> - [IW_IOCTL_IDX(SIOCSIWMODE)] = (iw_handler) cfg80211_wext_siwmode,
> - [IW_IOCTL_IDX(SIOCGIWMODE)] = (iw_handler) cfg80211_wext_giwmode,
> - [IW_IOCTL_IDX(SIOCGIWRANGE)] = (iw_handler) cfg80211_wext_giwrange,
> - [IW_IOCTL_IDX(SIOCSIWAP)] = (iw_handler) cfg80211_wext_siwap,
> - [IW_IOCTL_IDX(SIOCGIWAP)] = (iw_handler) cfg80211_wext_giwap,
> - [IW_IOCTL_IDX(SIOCSIWMLME)] = (iw_handler) cfg80211_wext_siwmlme,
> - [IW_IOCTL_IDX(SIOCSIWSCAN)] = (iw_handler) cfg80211_wext_siwscan,
> - [IW_IOCTL_IDX(SIOCGIWSCAN)] = (iw_handler) cfg80211_wext_giwscan,
> - [IW_IOCTL_IDX(SIOCSIWESSID)] = (iw_handler) cfg80211_wext_siwessid,
> - [IW_IOCTL_IDX(SIOCGIWESSID)] = (iw_handler) cfg80211_wext_giwessid,
> - [IW_IOCTL_IDX(SIOCSIWRATE)] = (iw_handler) cfg80211_wext_siwrate,
> - [IW_IOCTL_IDX(SIOCGIWRATE)] = (iw_handler) cfg80211_wext_giwrate,
> - [IW_IOCTL_IDX(SIOCSIWRTS)] = (iw_handler) cfg80211_wext_siwrts,
> - [IW_IOCTL_IDX(SIOCGIWRTS)] = (iw_handler) cfg80211_wext_giwrts,
> - [IW_IOCTL_IDX(SIOCSIWFRAG)] = (iw_handler) cfg80211_wext_siwfrag,
> - [IW_IOCTL_IDX(SIOCGIWFRAG)] = (iw_handler) cfg80211_wext_giwfrag,
> - [IW_IOCTL_IDX(SIOCSIWTXPOW)] = (iw_handler) cfg80211_wext_siwtxpower,
> - [IW_IOCTL_IDX(SIOCGIWTXPOW)] = (iw_handler) cfg80211_wext_giwtxpower,
> - [IW_IOCTL_IDX(SIOCSIWRETRY)] = (iw_handler) cfg80211_wext_siwretry,
> - [IW_IOCTL_IDX(SIOCGIWRETRY)] = (iw_handler) cfg80211_wext_giwretry,
> - [IW_IOCTL_IDX(SIOCSIWENCODE)] = (iw_handler) cfg80211_wext_siwencode,
> - [IW_IOCTL_IDX(SIOCGIWENCODE)] = (iw_handler) cfg80211_wext_giwencode,
> - [IW_IOCTL_IDX(SIOCSIWPOWER)] = (iw_handler) cfg80211_wext_siwpower,
> - [IW_IOCTL_IDX(SIOCGIWPOWER)] = (iw_handler) cfg80211_wext_giwpower,
> - [IW_IOCTL_IDX(SIOCSIWGENIE)] = (iw_handler) cfg80211_wext_siwgenie,
> - [IW_IOCTL_IDX(SIOCSIWAUTH)] = (iw_handler) cfg80211_wext_siwauth,
> - [IW_IOCTL_IDX(SIOCGIWAUTH)] = (iw_handler) cfg80211_wext_giwauth,
> - [IW_IOCTL_IDX(SIOCSIWENCODEEXT)]= (iw_handler) cfg80211_wext_siwencodeext,
> - [IW_IOCTL_IDX(SIOCSIWPMKSA)] = (iw_handler) cfg80211_wext_siwpmksa,
> + [IW_IOCTL_IDX(SIOCGIWNAME)] = __cfg80211_wext_giwname,
> + [IW_IOCTL_IDX(SIOCSIWFREQ)] = __cfg80211_wext_siwfreq,
> + [IW_IOCTL_IDX(SIOCGIWFREQ)] = __cfg80211_wext_giwfreq,
> + [IW_IOCTL_IDX(SIOCSIWMODE)] = __cfg80211_wext_siwmode,
> + [IW_IOCTL_IDX(SIOCGIWMODE)] = __cfg80211_wext_giwmode,
> + [IW_IOCTL_IDX(SIOCGIWRANGE)] = __cfg80211_wext_giwrange,
> + [IW_IOCTL_IDX(SIOCSIWAP)] = __cfg80211_wext_siwap,
> + [IW_IOCTL_IDX(SIOCGIWAP)] = __cfg80211_wext_giwap,
> + [IW_IOCTL_IDX(SIOCSIWMLME)] = __cfg80211_wext_siwmlme,
> + [IW_IOCTL_IDX(SIOCSIWSCAN)] = cfg80211_wext_siwscan,
> + [IW_IOCTL_IDX(SIOCGIWSCAN)] = __cfg80211_wext_giwscan,
> + [IW_IOCTL_IDX(SIOCSIWESSID)] = __cfg80211_wext_siwessid,
> + [IW_IOCTL_IDX(SIOCGIWESSID)] = __cfg80211_wext_giwessid,
> + [IW_IOCTL_IDX(SIOCSIWRATE)] = __cfg80211_wext_siwrate,
> + [IW_IOCTL_IDX(SIOCGIWRATE)] = __cfg80211_wext_giwrate,
> + [IW_IOCTL_IDX(SIOCSIWRTS)] = __cfg80211_wext_siwrts,
> + [IW_IOCTL_IDX(SIOCGIWRTS)] = __cfg80211_wext_giwrts,
> + [IW_IOCTL_IDX(SIOCSIWFRAG)] = __cfg80211_wext_siwfrag,
> + [IW_IOCTL_IDX(SIOCGIWFRAG)] = __cfg80211_wext_giwfrag,
> + [IW_IOCTL_IDX(SIOCSIWTXPOW)] = cfg80211_wext_siwtxpower,
> + [IW_IOCTL_IDX(SIOCGIWTXPOW)] = cfg80211_wext_giwtxpower,
> + [IW_IOCTL_IDX(SIOCSIWRETRY)] = __cfg80211_wext_siwretry,
> + [IW_IOCTL_IDX(SIOCGIWRETRY)] = __cfg80211_wext_giwretry,
> + [IW_IOCTL_IDX(SIOCSIWENCODE)] = __cfg80211_wext_siwencode,
> + [IW_IOCTL_IDX(SIOCGIWENCODE)] = __cfg80211_wext_giwencode,
> + [IW_IOCTL_IDX(SIOCSIWPOWER)] = __cfg80211_wext_siwpower,
> + [IW_IOCTL_IDX(SIOCGIWPOWER)] = __cfg80211_wext_giwpower,
> + [IW_IOCTL_IDX(SIOCSIWGENIE)] = __cfg80211_wext_siwgenie,
> + [IW_IOCTL_IDX(SIOCSIWAUTH)] = __cfg80211_wext_siwauth,
> + [IW_IOCTL_IDX(SIOCGIWAUTH)] = __cfg80211_wext_giwauth,
> + [IW_IOCTL_IDX(SIOCSIWENCODEEXT)]= __cfg80211_wext_siwencodeext,
> + [IW_IOCTL_IDX(SIOCSIWPMKSA)] = __cfg80211_wext_siwpmksa,
> };
>
> const struct iw_handler_def cfg80211_wext_handler = {
>
> base-commit: 9c87c9f41245baa3fc4716cf39141439cf405b01
> --
> 2.29.2.299.gdc1121823c-goog
>
--
Kees Cook
