wifi: cfg80211: optionally support monitor on disabled channels

If the hardware supports a disabled channel, it may in
some cases be possible to use monitor mode (without any
transmit) on it when it's otherwise disabled. Add a new
channel flag IEEE80211_CHAN_CAN_MONITOR that makes it
possible for a driver to indicate such a thing.

Make it per channel so drivers could have a choice with
it, perhaps it's only possible on some channels, perhaps
some channels are not supported at all, but still there
and marked disabled.

In _nl80211_parse_chandef() simplify the code and check
only for an unknown channel, _cfg80211_chandef_usable()
will later check for IEEE80211_CHAN_DISABLED anyway.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240206164849.87fad3a21a09.I9116b2fdc2e2c9fd59a9273a64db7fcb41fc0328@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 7bb8484e859e681eb620470969e165ad882670ac..0a3151587556eff1c6ef5959de62347317675b47 100644 (file)
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -122,6 +122,9 @@ struct wiphy;
  *     not permitted using this channel
  * @IEEE80211_CHAN_NO_6GHZ_AFC_CLIENT: Client connection with AFC AP
  *     not permitted using this channel
+ * @IEEE80211_CHAN_CAN_MONITOR: This channel can be used for monitor
+ *     mode even in the presence of other (regulatory) restrictions,
+ *     even if it is otherwise disabled.
  */
 enum ieee80211_channel_flags {
        IEEE80211_CHAN_DISABLED         = 1<<0,
@@ -148,6 +151,7 @@ enum ieee80211_channel_flags {
        IEEE80211_CHAN_DFS_CONCURRENT   = 1<<21,
        IEEE80211_CHAN_NO_6GHZ_VLP_CLIENT = 1<<22,
        IEEE80211_CHAN_NO_6GHZ_AFC_CLIENT = 1<<23,
+       IEEE80211_CHAN_CAN_MONITOR      = 1<<24,
 };
 
 #define IEEE80211_CHAN_NO_HT40 \

diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 13fa10804909ad9af0adc68533d9e92c010e8e39..546cc176c2a9917924d63c5bfbcedc4ae2500e6e 100644 (file)
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -4273,6 +4273,9 @@ enum nl80211_wmm_rule {
  *     not allowed using this channel
  * @NL80211_FREQUENCY_ATTR_NO_6GHZ_AFC_CLIENT: Client connection to AFC AP
  *     not allowed using this channel
+ * @NL80211_FREQUENCY_ATTR_CAN_MONITOR: This channel can be used in monitor
+ *     mode despite other (regulatory) restrictions, even if the channel is
+ *     otherwise completely disabled.
  * @NL80211_FREQUENCY_ATTR_MAX: highest frequency attribute number
  *     currently defined
  * @__NL80211_FREQUENCY_ATTR_AFTER_LAST: internal use
@@ -4315,6 +4318,7 @@ enum nl80211_frequency_attr {
        NL80211_FREQUENCY_ATTR_DFS_CONCURRENT,
        NL80211_FREQUENCY_ATTR_NO_6GHZ_VLP_CLIENT,
        NL80211_FREQUENCY_ATTR_NO_6GHZ_AFC_CLIENT,
+       NL80211_FREQUENCY_ATTR_CAN_MONITOR,
 
        /* keep last */
        __NL80211_FREQUENCY_ATTR_AFTER_LAST,

diff --git a/net/wireless/chan.c b/net/wireless/chan.c
index e2ce89afa9ffe9dfff3e1f912d1affd377491099..3414b2c3abcc543fdb8c643ac8e46c2bf5208f11 100644 (file)
--- a/net/wireless/chan.c
+++ b/net/wireless/chan.c
@@ -1145,7 +1145,7 @@ EXPORT_SYMBOL(cfg80211_chandef_dfs_cac_time);
 
 static bool cfg80211_secondary_chans_ok(struct wiphy *wiphy,
                                        u32 center_freq, u32 bandwidth,
-                                       u32 prohibited_flags)
+                                       u32 prohibited_flags, bool monitor)
 {
        struct ieee80211_channel *c;
        u32 freq, start_freq, end_freq;
@@ -1155,7 +1155,11 @@ static bool cfg80211_secondary_chans_ok(struct wiphy *wiphy,
 
        for (freq = start_freq; freq <= end_freq; freq += MHZ_TO_KHZ(20)) {
                c = ieee80211_get_channel_khz(wiphy, freq);
-               if (!c || c->flags & prohibited_flags)
+               if (!c)
+                       return false;
+               if (monitor && c->flags & IEEE80211_CHAN_CAN_MONITOR)
+                       continue;
+               if (c->flags & prohibited_flags)
                        return false;
        }
 
@@ -1215,9 +1219,9 @@ static bool cfg80211_edmg_usable(struct wiphy *wiphy, u8 edmg_channels,
        return true;
 }
 
-bool cfg80211_chandef_usable(struct wiphy *wiphy,
-                            const struct cfg80211_chan_def *chandef,
-                            u32 prohibited_flags)
+bool _cfg80211_chandef_usable(struct wiphy *wiphy,
+                             const struct cfg80211_chan_def *chandef,
+                             u32 prohibited_flags, bool monitor)
 {
        struct ieee80211_sta_ht_cap *ht_cap;
        struct ieee80211_sta_vht_cap *vht_cap;
@@ -1379,14 +1383,22 @@ bool cfg80211_chandef_usable(struct wiphy *wiphy,
 
        if (!cfg80211_secondary_chans_ok(wiphy,
                                         ieee80211_chandef_to_khz(chandef),
-                                        width, prohibited_flags))
+                                        width, prohibited_flags, monitor))
                return false;
 
        if (!chandef->center_freq2)
                return true;
        return cfg80211_secondary_chans_ok(wiphy,
                                           MHZ_TO_KHZ(chandef->center_freq2),
-                                          width, prohibited_flags);
+                                          width, prohibited_flags, monitor);
+}
+
+bool cfg80211_chandef_usable(struct wiphy *wiphy,
+                            const struct cfg80211_chan_def *chandef,
+                            u32 prohibited_flags)
+{
+       return _cfg80211_chandef_usable(wiphy, chandef, prohibited_flags,
+                                       false);
 }
 EXPORT_SYMBOL(cfg80211_chandef_usable);
 

diff --git a/net/wireless/core.h b/net/wireless/core.h
index debf63e6c61fc788c885e8849affe249fac32a83..118f2f6198289353241b9caf4f5bea1aa17cb634 100644 (file)
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -3,7 +3,7 @@
  * Wireless configuration interface internals.
  *
  * Copyright 2006-2010 Johannes Berg <johannes@sipsolutions.net>
- * Copyright (C) 2018-2023 Intel Corporation
+ * Copyright (C) 2018-2024 Intel Corporation
  */
 #ifndef __NET_WIRELESS_CORE_H
 #define __NET_WIRELESS_CORE_H
@@ -492,6 +492,9 @@ bool cfg80211_is_sub_chan(struct cfg80211_chan_def *chandef,
 bool cfg80211_wdev_on_sub_chan(struct wireless_dev *wdev,
                               struct ieee80211_channel *chan,
                               bool primary_only);
+bool _cfg80211_chandef_usable(struct wiphy *wiphy,
+                             const struct cfg80211_chan_def *chandef,
+                             u32 prohibited_flags, bool monitor);
 
 static inline unsigned int elapsed_jiffies_msecs(unsigned long start)
 {

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 3b3b511f9f69ecc32e0978782c5c5a882e0946a0..612ca99fbf39c05dfbc79a917175db115f7f99d5 100644 (file)
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -3218,9 +3218,9 @@ static bool nl80211_can_set_dev_channel(struct wireless_dev *wdev)
                wdev->iftype == NL80211_IFTYPE_P2P_GO;
 }
 
-int nl80211_parse_chandef(struct cfg80211_registered_device *rdev,
-                         struct genl_info *info,
-                         struct cfg80211_chan_def *chandef)
+static int _nl80211_parse_chandef(struct cfg80211_registered_device *rdev,
+                                 struct genl_info *info, bool monitor,
+                                 struct cfg80211_chan_def *chandef)
 {
        struct netlink_ext_ack *extack = info->extack;
        struct nlattr **attrs = info->attrs;
@@ -3245,10 +3245,9 @@ int nl80211_parse_chandef(struct cfg80211_registered_device *rdev,
        chandef->freq1_offset = control_freq % 1000;
        chandef->center_freq2 = 0;
 
-       /* Primary channel not allowed */
-       if (!chandef->chan || chandef->chan->flags & IEEE80211_CHAN_DISABLED) {
+       if (!chandef->chan) {
                NL_SET_ERR_MSG_ATTR(extack, attrs[NL80211_ATTR_WIPHY_FREQ],
-                                   "Channel is disabled");
+                                   "Unknown channel");
                return -EINVAL;
        }
 
@@ -3343,8 +3342,9 @@ int nl80211_parse_chandef(struct cfg80211_registered_device *rdev,
                return -EINVAL;
        }
 
-       if (!cfg80211_chandef_usable(&rdev->wiphy, chandef,
-                                    IEEE80211_CHAN_DISABLED)) {
+       if (!_cfg80211_chandef_usable(&rdev->wiphy, chandef,
+                                     IEEE80211_CHAN_DISABLED,
+                                     monitor)) {
                NL_SET_ERR_MSG(extack, "(extension) channel is disabled");
                return -EINVAL;
        }
@@ -3359,6 +3359,13 @@ int nl80211_parse_chandef(struct cfg80211_registered_device *rdev,
        return 0;
 }
 
+int nl80211_parse_chandef(struct cfg80211_registered_device *rdev,
+                         struct genl_info *info,
+                         struct cfg80211_chan_def *chandef)
+{
+       return _nl80211_parse_chandef(rdev, info, false, chandef);
+}
+
 static int __nl80211_set_channel(struct cfg80211_registered_device *rdev,
                                 struct net_device *dev,
                                 struct genl_info *info,
@@ -3383,7 +3390,9 @@ static int __nl80211_set_channel(struct cfg80211_registered_device *rdev,
                link_id = 0;
        }
 
-       result = nl80211_parse_chandef(rdev, info, &chandef);
+       result = _nl80211_parse_chandef(rdev, info,
+                                       iftype == NL80211_IFTYPE_MONITOR,
+                                       &chandef);
        if (result)
                return result;