wifi: mac80211: tests: add tests for ieee80211_determine_chan_mode

Add a few tests for ieee80211_determine_chan_mode that check that
mac80211 will not try to connect to an AP if an advertised basic rate is
not supported.

Signed-off-by: Benjamin Berg <[e-mail]>
Reviewed-by: Johannes Berg <[e-mail]>
Signed-off-by: Miri Korenblit <[e-mail]>
Link: https://patch.msgid.link/20250205110958.530c81eb7fdc.Ia77f5efdf9efb70d2766a3d6bf425553bcb308e8@changeid
Signed-off-by: Johannes Berg <[e-mail]>

net/mac80211/ieee80211_i.h

···
 void ieee80211_rearrange_tpe_psd(struct ieee80211_parsed_tpe_psd *psd,
 				 const struct cfg80211_chan_def *ap,
 				 const struct cfg80211_chan_def *used);
+struct ieee802_11_elems *
+ieee80211_determine_chan_mode(struct ieee80211_sub_if_data *sdata,
+			      struct ieee80211_conn_settings *conn,
+			      struct cfg80211_bss *cbss, int link_id,
+			      struct ieee80211_chan_req *chanreq,
+			      struct cfg80211_chan_def *ap_chandef,
+			      unsigned long *userspace_selectors);
 #else
 #define EXPORT_SYMBOL_IF_MAC80211_KUNIT(sym)
 #define VISIBLE_IF_MAC80211_KUNIT static

net/mac80211/mlme.c

···
 	chanreq->ap = *ap_chandef;
 }
 
-static struct ieee802_11_elems *
+VISIBLE_IF_MAC80211_KUNIT struct ieee802_11_elems *
 ieee80211_determine_chan_mode(struct ieee80211_sub_if_data *sdata,
 			      struct ieee80211_conn_settings *conn,
 			      struct cfg80211_bss *cbss, int link_id,
···
 	kfree(elems);
 	return ERR_PTR(ret);
 }
+EXPORT_SYMBOL_IF_MAC80211_KUNIT(ieee80211_determine_chan_mode);
 
 static int ieee80211_config_bw(struct ieee80211_link_data *link,
 			       struct ieee802_11_elems *elems,

net/mac80211/tests/Makefile

···
-mac80211-tests-y += module.o util.o elems.o mfp.o tpe.o
+mac80211-tests-y += module.o util.o elems.o mfp.o tpe.o chan-mode.o
 
 obj-$(CONFIG_MAC80211_KUNIT_TEST) += mac80211-tests.o

net/mac80211/tests/chan-mode.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * KUnit tests for channel mode functions
+ *
+ * Copyright (C) 2024 Intel Corporation
+ */
+#include <net/cfg80211.h>
+#include <kunit/test.h>
+
+#include "util.h"
+
+MODULE_IMPORT_NS("EXPORTED_FOR_KUNIT_TESTING");
+
+static const struct determine_chan_mode_case {
+	const char *desc;
+	u8 extra_supp_rate;
+	enum ieee80211_conn_mode conn_mode;
+	enum ieee80211_conn_mode expected_mode;
+	bool strict;
+	u8 userspace_selector;
+	struct ieee80211_ht_cap ht_capa_mask;
+	struct ieee80211_vht_cap vht_capa;
+	struct ieee80211_vht_cap vht_capa_mask;
+	u8 vht_basic_mcs_1_4_set:1,
+	   vht_basic_mcs_5_8_set:1,
+	   he_basic_mcs_1_4_set:1,
+	   he_basic_mcs_5_8_set:1;
+	u8 vht_basic_mcs_1_4, vht_basic_mcs_5_8;
+	u8 he_basic_mcs_1_4, he_basic_mcs_5_8;
+	u8 eht_mcs7_min_nss;
+	int error;
+} determine_chan_mode_cases[] = {
+	{
+		.desc = "Normal case, EHT is working",
+		.conn_mode = IEEE80211_CONN_MODE_EHT,
+		.expected_mode = IEEE80211_CONN_MODE_EHT,
+	}, {
+		.desc = "Requiring EHT support is fine",
+		.conn_mode = IEEE80211_CONN_MODE_EHT,
+		.expected_mode = IEEE80211_CONN_MODE_EHT,
+		.extra_supp_rate = 0x80 | BSS_MEMBERSHIP_SELECTOR_EHT_PHY,
+	}, {
+		.desc = "Lowering the mode limits us",
+		.conn_mode = IEEE80211_CONN_MODE_VHT,
+		.expected_mode = IEEE80211_CONN_MODE_VHT,
+	}, {
+		.desc = "Requesting a basic rate/selector that we do not support",
+		.conn_mode = IEEE80211_CONN_MODE_EHT,
+		.extra_supp_rate = 0x80 | (BSS_MEMBERSHIP_SELECTOR_MIN - 1),
+		.error = EINVAL,
+	}, {
+		.desc = "As before, but userspace says it is taking care of it",
+		.conn_mode = IEEE80211_CONN_MODE_EHT,
+		.userspace_selector = BSS_MEMBERSHIP_SELECTOR_MIN - 1,
+		.extra_supp_rate = 0x80 | (BSS_MEMBERSHIP_SELECTOR_MIN - 1),
+		.expected_mode = IEEE80211_CONN_MODE_EHT,
+	}, {
+		.desc = "Masking out a supported rate in HT capabilities",
+		.conn_mode = IEEE80211_CONN_MODE_EHT,
+		.expected_mode = IEEE80211_CONN_MODE_LEGACY,
+		.ht_capa_mask = {
+			.mcs.rx_mask[0] = 0xf7,
+		},
+	}, {
+		.desc = "Masking out a RX rate in VHT capabilities",
+		.conn_mode = IEEE80211_CONN_MODE_EHT,
+		.expected_mode = IEEE80211_CONN_MODE_HT,
+		/* Only one RX stream at MCS 0-7 */
+		.vht_capa = {
+			.supp_mcs.rx_mcs_map =
+				cpu_to_le16(IEEE80211_VHT_MCS_SUPPORT_0_7),
+		},
+		.vht_capa_mask = {
+			.supp_mcs.rx_mcs_map = cpu_to_le16(0xffff),
+		},
+		.strict = true,
+	}, {
+		.desc = "Masking out a TX rate in VHT capabilities",
+		.conn_mode = IEEE80211_CONN_MODE_EHT,
+		.expected_mode = IEEE80211_CONN_MODE_HT,
+		/* Only one TX stream at MCS 0-7 */
+		.vht_capa = {
+			.supp_mcs.tx_mcs_map =
+				cpu_to_le16(IEEE80211_VHT_MCS_SUPPORT_0_7),
+		},
+		.vht_capa_mask = {
+			.supp_mcs.tx_mcs_map = cpu_to_le16(0xffff),
+		},
+		.strict = true,
+	}, {
+		.desc = "AP has higher VHT requirement than client",
+		.conn_mode = IEEE80211_CONN_MODE_EHT,
+		.expected_mode = IEEE80211_CONN_MODE_HT,
+		.vht_basic_mcs_5_8_set = 1,
+		.vht_basic_mcs_5_8 = 0xFE, /* require 5th stream */
+		.strict = true,
+	}, {
+		.desc = "all zero VHT basic rates are ignored (many APs broken)",
+		.conn_mode = IEEE80211_CONN_MODE_VHT,
+		.expected_mode = IEEE80211_CONN_MODE_VHT,
+		.vht_basic_mcs_1_4_set = 1,
+		.vht_basic_mcs_5_8_set = 1,
+	}, {
+		.desc = "AP requires 3 HE streams but client only has two",
+		.conn_mode = IEEE80211_CONN_MODE_EHT,
+		.expected_mode = IEEE80211_CONN_MODE_VHT,
+		.he_basic_mcs_1_4 = 0b11001010,
+		.he_basic_mcs_1_4_set = 1,
+	}, {
+		.desc = "all zero HE basic rates are ignored (iPhone workaround)",
+		.conn_mode = IEEE80211_CONN_MODE_HE,
+		.expected_mode = IEEE80211_CONN_MODE_HE,
+		.he_basic_mcs_1_4_set = 1,
+		.he_basic_mcs_5_8_set = 1,
+	}, {
+		.desc = "AP requires too many RX streams with EHT MCS 7",
+		.conn_mode = IEEE80211_CONN_MODE_EHT,
+		.expected_mode = IEEE80211_CONN_MODE_HE,
+		.eht_mcs7_min_nss = 0x15,
+	}, {
+		.desc = "AP requires too many TX streams with EHT MCS 7",
+		.conn_mode = IEEE80211_CONN_MODE_EHT,
+		.expected_mode = IEEE80211_CONN_MODE_HE,
+		.eht_mcs7_min_nss = 0x51,
+	}, {
+		.desc = "AP requires too many RX streams with EHT MCS 7 and EHT is required",
+		.extra_supp_rate = 0x80 | BSS_MEMBERSHIP_SELECTOR_EHT_PHY,
+		.conn_mode = IEEE80211_CONN_MODE_EHT,
+		.eht_mcs7_min_nss = 0x15,
+		.error = EINVAL,
+	}
+};
+KUNIT_ARRAY_PARAM_DESC(determine_chan_mode, determine_chan_mode_cases, desc)
+
+static void test_determine_chan_mode(struct kunit *test)
+{
+	const struct determine_chan_mode_case *params = test->param_value;
+	struct t_sdata *t_sdata = T_SDATA(test);
+	struct ieee80211_conn_settings conn = {
+		.mode = params->conn_mode,
+		.bw_limit = IEEE80211_CONN_BW_LIMIT_20,
+	};
+	struct cfg80211_bss cbss = {
+		.channel = &t_sdata->band_5ghz.channels[0],
+	};
+	unsigned long userspace_selectors[BITS_TO_LONGS(128)] = {};
+	u8 bss_ies[] = {
+		/* Supported Rates */
+		WLAN_EID_SUPP_RATES, 0x08,
+		0x82, 0x84, 0x8b, 0x96, 0xc, 0x12, 0x18, 0x24,
+		/* Extended Supported Rates */
+		WLAN_EID_EXT_SUPP_RATES, 0x05,
+		0x30, 0x48, 0x60, 0x6c, params->extra_supp_rate,
+		/* HT Capabilities */
+		WLAN_EID_HT_CAPABILITY, 0x1a,
+		0x0c, 0x00, 0x1b, 0xff, 0xff, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00,
+		/* HT Information (0xff for 1 stream) */
+		WLAN_EID_HT_OPERATION, 0x16,
+		0x24, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		/* VHT Capabilities */
+		WLAN_EID_VHT_CAPABILITY, 0xc,
+		0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0x00, 0x00,
+		0xff, 0xff, 0x00, 0x00,
+		/* VHT Operation */
+		WLAN_EID_VHT_OPERATION, 0x05,
+		0x00, 0x00, 0x00,
+		params->vht_basic_mcs_1_4_set ?
+			params->vht_basic_mcs_1_4 :
+			le16_get_bits(t_sdata->band_5ghz.vht_cap.vht_mcs.rx_mcs_map, 0xff),
+		params->vht_basic_mcs_5_8_set ?
+			params->vht_basic_mcs_5_8 :
+			le16_get_bits(t_sdata->band_5ghz.vht_cap.vht_mcs.rx_mcs_map, 0xff00),
+		/* HE Capabilities */
+		WLAN_EID_EXTENSION, 0x16, WLAN_EID_EXT_HE_CAPABILITY,
+		0x01, 0x78, 0xc8, 0x1a, 0x40, 0x00, 0x00, 0xbf,
+		0xce, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0xfa, 0xff, 0xfa, 0xff,
+		/* HE Operation (permit overriding values) */
+		WLAN_EID_EXTENSION, 0x07, WLAN_EID_EXT_HE_OPERATION,
+		0xf0, 0x3f, 0x00, 0xb0,
+		params->he_basic_mcs_1_4_set ? params->he_basic_mcs_1_4 : 0xfc,
+		params->he_basic_mcs_5_8_set ? params->he_basic_mcs_5_8 : 0xff,
+		/* EHT Capabilities */
+		WLAN_EID_EXTENSION, 0x12, WLAN_EID_EXT_EHT_CAPABILITY,
+		0x07, 0x00, 0x1c, 0x00, 0x00, 0xfe, 0xff, 0xff,
+		0x7f, 0x01, 0x00, 0x88, 0x88, 0x88, 0x00, 0x00,
+		0x00,
+		/* EHT Operation */
+		WLAN_EID_EXTENSION, 0x09, WLAN_EID_EXT_EHT_OPERATION,
+		0x01, params->eht_mcs7_min_nss ? params->eht_mcs7_min_nss : 0x11,
+		0x00, 0x00, 0x00, 0x00, 0x24, 0x00,
+	};
+	struct ieee80211_chan_req chanreq = {};
+	struct cfg80211_chan_def ap_chandef = {};
+	struct ieee802_11_elems *elems;
+
+	if (params->strict)
+		set_bit(IEEE80211_HW_STRICT, t_sdata->local.hw.flags);
+	else
+		clear_bit(IEEE80211_HW_STRICT, t_sdata->local.hw.flags);
+
+	t_sdata->sdata->u.mgd.ht_capa_mask = params->ht_capa_mask;
+	t_sdata->sdata->u.mgd.vht_capa = params->vht_capa;
+	t_sdata->sdata->u.mgd.vht_capa_mask = params->vht_capa_mask;
+
+	if (params->userspace_selector)
+		set_bit(params->userspace_selector, userspace_selectors);
+
+	rcu_assign_pointer(cbss.ies,
+			   kunit_kzalloc(test,
+					 sizeof(cbss) + sizeof(bss_ies),
+					 GFP_KERNEL));
+	KUNIT_ASSERT_NOT_NULL(test, rcu_access_pointer(cbss.ies));
+	((struct cfg80211_bss_ies *)rcu_access_pointer(cbss.ies))->len = sizeof(bss_ies);
+
+	memcpy((void *)rcu_access_pointer(cbss.ies)->data, bss_ies,
+	       sizeof(bss_ies));
+
+	rcu_read_lock();
+	elems = ieee80211_determine_chan_mode(t_sdata->sdata, &conn, &cbss,
+					      0, &chanreq, &ap_chandef,
+					      userspace_selectors);
+	rcu_read_unlock();
+
+	/* We do not need elems, free them if they are valid. */
+	if (!IS_ERR_OR_NULL(elems))
+		kfree(elems);
+
+	if (params->error) {
+		KUNIT_ASSERT_TRUE(test, IS_ERR(elems));
+		KUNIT_ASSERT_EQ(test, PTR_ERR(elems), -params->error);
+	} else {
+		KUNIT_ASSERT_NOT_ERR_OR_NULL(test, elems);
+		KUNIT_ASSERT_EQ(test, conn.mode, params->expected_mode);
+	}
+}
+
+static struct kunit_case chan_mode_cases[] = {
+	KUNIT_CASE_PARAM(test_determine_chan_mode,
+			 determine_chan_mode_gen_params),
+	{}
+};
+
+static struct kunit_suite chan_mode = {
+	.name = "mac80211-mlme-chan-mode",
+	.test_cases = chan_mode_cases,
+};
+
+kunit_test_suite(chan_mode);

net/mac80211/tests/util.c

···
 				cpu_to_le16(IEEE80211_VHT_MCS_SUPPORT_0_9 << 0 |
 					    IEEE80211_VHT_MCS_SUPPORT_0_9 << 2 |
 					    IEEE80211_VHT_MCS_SUPPORT_0_9 << 4 |
-					    IEEE80211_VHT_MCS_SUPPORT_0_9 << 6 |
-					    IEEE80211_VHT_MCS_SUPPORT_0_9 << 8 |
-					    IEEE80211_VHT_MCS_SUPPORT_0_9 << 10 |
-					    IEEE80211_VHT_MCS_SUPPORT_0_9 << 12 |
-					    IEEE80211_VHT_MCS_SUPPORT_0_9 << 14);
+					    IEEE80211_VHT_MCS_SUPPORT_0_9 << 6);
 			sband->vht_cap.vht_mcs.tx_mcs_map =
 				sband->vht_cap.vht_mcs.rx_mcs_map;
 			break;