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From:   gregory.greenman@intel.com
To:     johannes@sipsolutions.net
Cc:     linux-wireless@vger.kernel.org,
        Ayala Beker <ayala.beker@intel.com>,
        Gregory Greenman <gregory.greenman@intel.com>
Subject: [PATCH 03/18] wifi: mac80211: don't connect to an AP while it's in a CSA process
Date:   Mon, 18 Sep 2023 14:10:48 +0300
Message-Id: <20230918140607.dca69ce27501.I9745c695f3403b259ad000ce94110588a836c04a@changeid>
In-Reply-To: <20230918111103.435195-1-gregory.greenman@intel.com>
References: <20230918111103.435195-1-gregory.greenman@intel.com>
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From: Ayala Beker <ayala.beker@intel.com>

Connection to an AP that is running a CSA flow may end up with a
failure as the AP might change its channel during the connection
flow while we do not track the channel change yet.
Avoid that by rejecting a connection to such an AP.

Signed-off-by: Ayala Beker <ayala.beker@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
---
 net/mac80211/mlme.c | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index a211f594f25a..a85873f305bf 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -7015,6 +7015,7 @@ int ieee80211_mgd_auth(struct ieee80211_sub_if_data *sdata,
 	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
 	struct ieee80211_mgd_auth_data *auth_data;
 	struct ieee80211_link_data *link;
+	const struct element *csa_elem, *ecsa_elem;
 	u16 auth_alg;
 	int err;
 	bool cont_auth;
@@ -7057,6 +7058,22 @@ int ieee80211_mgd_auth(struct ieee80211_sub_if_data *sdata,
 	if (ifmgd->assoc_data)
 		return -EBUSY;
 
+	rcu_read_lock();
+	csa_elem = ieee80211_bss_get_elem(req->bss, WLAN_EID_CHANNEL_SWITCH);
+	ecsa_elem = ieee80211_bss_get_elem(req->bss,
+					   WLAN_EID_EXT_CHANSWITCH_ANN);
+	if ((csa_elem &&
+	     csa_elem->datalen == sizeof(struct ieee80211_channel_sw_ie) &&
+	     ((struct ieee80211_channel_sw_ie *)csa_elem->data)->count != 0) ||
+	    (ecsa_elem &&
+	     ecsa_elem->datalen == sizeof(struct ieee80211_ext_chansw_ie) &&
+	     ((struct ieee80211_ext_chansw_ie *)ecsa_elem->data)->count != 0)) {
+		rcu_read_unlock();
+		sdata_info(sdata, "AP is in CSA process, reject auth\n");
+		return -EINVAL;
+	}
+	rcu_read_unlock();
+
 	auth_data = kzalloc(sizeof(*auth_data) + req->auth_data_len +
 			    req->ie_len, GFP_KERNEL);
 	if (!auth_data)
@@ -7364,7 +7381,7 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
 	struct ieee80211_local *local = sdata->local;
 	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
 	struct ieee80211_mgd_assoc_data *assoc_data;
-	const struct element *ssid_elem;
+	const struct element *ssid_elem, *csa_elem, *ecsa_elem;
 	struct ieee80211_vif_cfg *vif_cfg = &sdata->vif.cfg;
 	ieee80211_conn_flags_t conn_flags = 0;
 	struct ieee80211_link_data *link;
@@ -7394,6 +7411,21 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
 		kfree(assoc_data);
 		return -EINVAL;
 	}
+
+	csa_elem = ieee80211_bss_get_elem(cbss, WLAN_EID_CHANNEL_SWITCH);
+	ecsa_elem = ieee80211_bss_get_elem(cbss, WLAN_EID_EXT_CHANSWITCH_ANN);
+	if ((csa_elem &&
+	     csa_elem->datalen == sizeof(struct ieee80211_channel_sw_ie) &&
+	     ((struct ieee80211_channel_sw_ie *)csa_elem->data)->count != 0) ||
+	    (ecsa_elem &&
+	     ecsa_elem->datalen == sizeof(struct ieee80211_ext_chansw_ie) &&
+	     ((struct ieee80211_ext_chansw_ie *)ecsa_elem->data)->count != 0)) {
+		sdata_info(sdata, "AP is in CSA process, reject assoc\n");
+		rcu_read_unlock();
+		kfree(assoc_data);
+		return -EINVAL;
+	}
+
 	memcpy(assoc_data->ssid, ssid_elem->data, ssid_elem->datalen);
 	assoc_data->ssid_len = ssid_elem->datalen;
 	memcpy(vif_cfg->ssid, assoc_data->ssid, assoc_data->ssid_len);
-- 
2.38.1