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wifi: mac80211: improve CSA/ECSA connection refusal
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[ Upstream commit 35e2385 ]

As mentioned in the previous commit, we pretty quickly found
that some APs have ECSA elements stuck in their probe response,
so using that to not attempt to connect while CSA is happening
we never connect to such an AP.

Improve this situation by checking more carefully and ignoring
the ECSA if cfg80211 has previously detected the ECSA element
being stuck in the probe response.

Additionally, allow connecting to an AP that's switching to a
channel it's already using, unless it's using quiet mode. In
this case, we may just have to adjust bandwidth later. If it's
actually switching channels, it's better not to try to connect
in the middle of that.

Reported-by: coldolt <andypalmadi@gmail.com>
Closes: https://lore.kernel.org/linux-wireless/CAJvGw+DQhBk_mHXeu6RTOds5iramMW2FbMB01VbKRA4YbHHDTA@mail.gmail.com/
Fixes: c09c4f3 ("wifi: mac80211: don't connect to an AP while it's in a CSA process")
Reviewed-by: Miriam Rachel Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240129131413.cc2d0a26226e.I682c016af76e35b6c47007db50e8554c5a426910@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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@jmberg-intel @gregkh
jmberg-intel authored and gregkh committed Feb 16, 2024
1 parent ce112c9 commit ea88bde
Showing 1 changed file with 76 additions and 27 deletions.
103 changes: 76 additions & 27 deletions net/mac80211/mlme.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -7288,6 +7288,75 @@ static int ieee80211_prep_connection(struct ieee80211_sub_if_data *sdata,
return err;
}

static bool ieee80211_mgd_csa_present(struct ieee80211_sub_if_data *sdata,
const struct cfg80211_bss_ies *ies,
u8 cur_channel, bool ignore_ecsa)
{
const struct element *csa_elem, *ecsa_elem;
struct ieee80211_channel_sw_ie *csa = NULL;
struct ieee80211_ext_chansw_ie *ecsa = NULL;

if (!ies)
return false;

csa_elem = cfg80211_find_elem(WLAN_EID_CHANNEL_SWITCH,
ies->data, ies->len);
if (csa_elem && csa_elem->datalen == sizeof(*csa))
csa = (void *)csa_elem->data;

ecsa_elem = cfg80211_find_elem(WLAN_EID_EXT_CHANSWITCH_ANN,
ies->data, ies->len);
if (ecsa_elem && ecsa_elem->datalen == sizeof(*ecsa))
ecsa = (void *)ecsa_elem->data;

if (csa && csa->count == 0)
csa = NULL;
if (csa && !csa->mode && csa->new_ch_num == cur_channel)
csa = NULL;

if (ecsa && ecsa->count == 0)
ecsa = NULL;
if (ecsa && !ecsa->mode && ecsa->new_ch_num == cur_channel)
ecsa = NULL;

if (ignore_ecsa && ecsa) {
sdata_info(sdata,
"Ignoring ECSA in probe response - was considered stuck!\n");
return csa;
}

return csa || ecsa;
}

static bool ieee80211_mgd_csa_in_process(struct ieee80211_sub_if_data *sdata,
struct cfg80211_bss *bss)
{
u8 cur_channel;
bool ret;

cur_channel = ieee80211_frequency_to_channel(bss->channel->center_freq);

rcu_read_lock();
if (ieee80211_mgd_csa_present(sdata,
rcu_dereference(bss->beacon_ies),
cur_channel, false)) {
ret = true;
goto out;
}

if (ieee80211_mgd_csa_present(sdata,
rcu_dereference(bss->proberesp_ies),
cur_channel, bss->proberesp_ecsa_stuck)) {
ret = true;
goto out;
}

ret = false;
out:
rcu_read_unlock();
return ret;
}

/* config hooks */
int ieee80211_mgd_auth(struct ieee80211_sub_if_data *sdata,
struct cfg80211_auth_request *req)
Expand All @@ -7296,7 +7365,6 @@ 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;
Expand Down Expand Up @@ -7339,21 +7407,10 @@ 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();
if (ieee80211_mgd_csa_in_process(sdata, req->bss)) {
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);
Expand Down Expand Up @@ -7662,7 +7719,7 @@ 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, *csa_elem, *ecsa_elem;
const struct element *ssid_elem;
struct ieee80211_vif_cfg *vif_cfg = &sdata->vif.cfg;
ieee80211_conn_flags_t conn_flags = 0;
struct ieee80211_link_data *link;
Expand All @@ -7685,23 +7742,15 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,

cbss = req->link_id < 0 ? req->bss : req->links[req->link_id].bss;

rcu_read_lock();
ssid_elem = ieee80211_bss_get_elem(cbss, WLAN_EID_SSID);
if (!ssid_elem || ssid_elem->datalen > sizeof(assoc_data->ssid)) {
rcu_read_unlock();
if (ieee80211_mgd_csa_in_process(sdata, cbss)) {
sdata_info(sdata, "AP is in CSA process, reject assoc\n");
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_lock();
ssid_elem = ieee80211_bss_get_elem(cbss, WLAN_EID_SSID);
if (!ssid_elem || ssid_elem->datalen > sizeof(assoc_data->ssid)) {
rcu_read_unlock();
kfree(assoc_data);
return -EINVAL;
Expand Down

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