nl80211: fix scheduled scan RSSI matchset attribute confusion

The scheduled scan matchsets were intended to be a list of filters, with the found BSS having to pass at least one of them to be passed to the host. When the RSSI attribute was added, however, this was broken and currently wpa_supplicant adds that attribute in its own matchset; however, it doesn't intend that to mean that anything that passes the RSSI filter should be passed to the host, instead it wants it to mean that everything needs to also have higher RSSI. This is semantically problematic because we have a list of filters like [ SSID1, SSID2, SSID3, RSSI ] with no real indication which one should be OR'ed and which one AND'ed. To fix this, move the RSSI filter attribute into each matchset. As we need to stay backward compatible, treat a matchset with only the RSSI attribute as a "default RSSI filter" for all other matchsets, but only if there are other matchsets (an RSSI-only matchset by itself is still desirable.) To make driver implementation easier, keep a global min_rssi_thold for the entire request as well. The only affected driver is ath6kl. I found this when I looked into the code after Raja Mani submitted a patch fixing the n_match_sets calculation to disregard the RSSI, but that patch didn't address the semantic issue.

Johannes Berg committed 12 years ago

Commit ea73cbc1 parent 9fa37a35 files · +92 −19Browse files

Unified · Split

5 files

drivers/net/wireless/ath/ath6kl/cfg80211.c +14 −5
drivers/net/wireless/iwlwifi/mvm/scan.c +3 −0
include/net/cfg80211.h +6 −3
include/uapi/linux/nl80211.h +8 −2
net/wireless/nl80211.c +61 −9

drivers/net/wireless/ath/ath6kl/cfg80211.c+14−5

@@ -3256,6 +3256,15 @@ static int ath6kl_cfg80211_sscan_start(struct wiphy *wiphy, · 3255 unmodified lines
3256	3256	struct ath6kl_vif *vif = netdev_priv(dev);
3257	3257	u16 interval;
3258	3258	int ret, rssi_thold;
	3259	+ int n_match_sets = request->n_match_sets;
	3260	+
	3261	+ /*
	3262	+ * If there's a matchset w/o an SSID, then assume it's just for
	3263	+ * the RSSI (nothing else is currently supported) and ignore it.
	3264	+ * The device only supports a global RSSI filter that we set below.
	3265	+ */
	3266	+ if (n_match_sets == 1 && !request->match_sets[0].ssid.ssid_len)
	3267	+ n_match_sets = 0;
3259	3268
3260	3269	if (ar->state != ATH6KL_STATE_ON)
3261	3270	return -EIO;
@@ -3268,11 +3277,11 @@ static int ath6kl_cfg80211_sscan_start(struct wiphy *wiphy, · 6 unmodified lines
3268	3277	ret = ath6kl_set_probed_ssids(ar, vif, request->ssids,
3269	3278	request->n_ssids,
3270	3279	request->match_sets,
3271		− request->n_match_sets);
	3280	+ n_match_sets);
3272	3281	if (ret < 0)
3273	3282	return ret;
3274	3283
3275		− if (!request->n_match_sets) {
	3284	+ if (!n_match_sets) {
3276	3285	ret = ath6kl_wmi_bssfilter_cmd(ar->wmi, vif->fw_vif_idx,
3277	3286	ALL_BSS_FILTER, 0);
3278	3287	if (ret < 0)
@@ -3286,12 +3295,12 @@ static int ath6kl_cfg80211_sscan_start(struct wiphy *wiphy, · 7 unmodified lines
3286	3295
3287	3296	if (test_bit(ATH6KL_FW_CAPABILITY_RSSI_SCAN_THOLD,
3288	3297	ar->fw_capabilities)) {
3289		− if (request->rssi_thold <= NL80211_SCAN_RSSI_THOLD_OFF)
	3298	+ if (request->min_rssi_thold <= NL80211_SCAN_RSSI_THOLD_OFF)
3290	3299	rssi_thold = 0;
3291		− else if (request->rssi_thold < -127)
	3300	+ else if (request->min_rssi_thold < -127)
3292	3301	rssi_thold = -127;
3293	3302	else
3294		− rssi_thold = request->rssi_thold;
	3303	+ rssi_thold = request->min_rssi_thold;
3295	3304
3296	3305	ret = ath6kl_wmi_set_rssi_filter_cmd(ar->wmi, vif->fw_vif_idx,
3297	3306	rssi_thold);

drivers/net/wireless/iwlwifi/mvm/scan.c+3−0

@@ -595,6 +595,9 @@ static void iwl_scan_offload_build_ssid(struct cfg80211_sched_scan_request *req, · 594 unmodified lines
595	595	* config match list.
596	596	*/
597	597	for (i = 0; i < req->n_match_sets && i < PROBE_OPTION_MAX; i++) {
	598	+ /* skip empty SSID matchsets */
	599	+ if (!req->match_sets[i].ssid.ssid_len)
	600	+ continue;
598	601	scan->direct_scan[i].id = WLAN_EID_SSID;
599	602	scan->direct_scan[i].len = req->match_sets[i].ssid.ssid_len;
600	603	memcpy(scan->direct_scan[i].ssid, req->match_sets[i].ssid.ssid,

include/net/cfg80211.h+6−3

@@ -1394,10 +1394,12 @@ struct cfg80211_scan_request { · 1393 unmodified lines
1394	1394	/**
1395	1395	* struct cfg80211_match_set - sets of attributes to match
1396	1396	*
1397		− * @ssid: SSID to be matched
	1397	+ * @ssid: SSID to be matched; may be zero-length for no match (RSSI only)
	1398	+ * @rssi_thold: don't report scan results below this threshold (in s32 dBm)
1398	1399	*/
1399	1400	struct cfg80211_match_set {
1400	1401	struct cfg80211_ssid ssid;
	1402	+ s32 rssi_thold;
1401	1403	};
1402	1404
1403	1405	/**
@@ -1420,7 +1422,8 @@ struct cfg80211_match_set { · 16 unmodified lines
1420	1422	* @dev: the interface
1421	1423	* @scan_start: start time of the scheduled scan
1422	1424	* @channels: channels to scan
1423		− * @rssi_thold: don't report scan results below this threshold (in s32 dBm)
	1425	+ * @min_rssi_thold: for drivers only supporting a single threshold, this
	1426	+ * contains the minimum over all matchsets
1424	1427	*/
1425	1428	struct cfg80211_sched_scan_request {
1426	1429	struct cfg80211_ssid *ssids;
@@ -1433,7 +1436,7 @@ struct cfg80211_sched_scan_request { · 6 unmodified lines
1433	1436	u32 flags;
1434	1437	struct cfg80211_match_set *match_sets;
1435	1438	int n_match_sets;
1436		− s32 rssi_thold;
	1439	+ s32 min_rssi_thold;
1437	1440
1438	1441	/* internal */
1439	1442	struct wiphy *wiphy;

include/uapi/linux/nl80211.h+8−2

@@ -2467,9 +2467,15 @@ enum nl80211_reg_rule_attr { · 2466 unmodified lines
2467	2467	* enum nl80211_sched_scan_match_attr - scheduled scan match attributes
2468	2468	* @__NL80211_SCHED_SCAN_MATCH_ATTR_INVALID: attribute number 0 is reserved
2469	2469	* @NL80211_SCHED_SCAN_MATCH_ATTR_SSID: SSID to be used for matching,
2470		− * only report BSS with matching SSID.
	2470	+ * only report BSS with matching SSID.
2471	2471	* @NL80211_SCHED_SCAN_MATCH_ATTR_RSSI: RSSI threshold (in dBm) for reporting a
2472		− * BSS in scan results. Filtering is turned off if not specified.
	2472	+ * BSS in scan results. Filtering is turned off if not specified. Note that
	2473	+ * if this attribute is in a match set of its own, then it is treated as
	2474	+ * the default value for all matchsets with an SSID, rather than being a
	2475	+ * matchset of its own without an RSSI filter. This is due to problems with
	2476	+ * how this API was implemented in the past. Also, due to the same problem,
	2477	+ * the only way to create a matchset with only an RSSI filter (with this
	2478	+ * attribute) is if there's only a single matchset with the RSSI attribute.
2473	2479	* @NL80211_SCHED_SCAN_MATCH_ATTR_MAX: highest scheduled scan filter
2474	2480	* attribute number currently defined
2475	2481	* @__NL80211_SCHED_SCAN_MATCH_ATTR_AFTER_LAST: internal use

net/wireless/nl80211.c+61−9

@@ -5467,6 +5467,7 @@ static int nl80211_start_sched_scan(struct sk_buff *skb, · 5466 unmodified lines
5467	5467	enum ieee80211_band band;
5468	5468	size_t ie_len;
5469	5469	struct nlattr *tb[NL80211_SCHED_SCAN_MATCH_ATTR_MAX + 1];
	5470	+ s32 default_match_rssi = NL80211_SCAN_RSSI_THOLD_OFF;
5470	5471
5471	5472	if (!(rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_SCHED_SCAN) \|\|
5472	5473	!rdev->ops->sched_scan_start)
@@ -5501,11 +5502,40 @@ static int nl80211_start_sched_scan(struct sk_buff *skb, · 28 unmodified lines
5501	5502	if (n_ssids > wiphy->max_sched_scan_ssids)
5502	5503	return -EINVAL;
5503	5504
5504		− if (info->attrs[NL80211_ATTR_SCHED_SCAN_MATCH])
	5505	+ /*
	5506	+ * First, count the number of 'real' matchsets. Due to an issue with
	5507	+ * the old implementation, matchsets containing only the RSSI attribute
	5508	+ * (NL80211_SCHED_SCAN_MATCH_ATTR_RSSI) are considered as the 'default'
	5509	+ * RSSI for all matchsets, rather than their own matchset for reporting
	5510	+ * all APs with a strong RSSI. This is needed to be compatible with
	5511	+ * older userspace that treated a matchset with only the RSSI as the
	5512	+ * global RSSI for all other matchsets - if there are other matchsets.
	5513	+ */
	5514	+ if (info->attrs[NL80211_ATTR_SCHED_SCAN_MATCH]) {
5505	5515	nla_for_each_nested(attr,
5506	5516	info->attrs[NL80211_ATTR_SCHED_SCAN_MATCH],
5507		− tmp)
5508		− n_match_sets++;
	5517	+ tmp) {
	5518	+ struct nlattr *rssi;
	5519	+
	5520	+ err = nla_parse(tb, NL80211_SCHED_SCAN_MATCH_ATTR_MAX,
	5521	+ nla_data(attr), nla_len(attr),
	5522	+ nl80211_match_policy);
	5523	+ if (err)
	5524	+ return err;
	5525	+ /* add other standalone attributes here */
	5526	+ if (tb[NL80211_SCHED_SCAN_MATCH_ATTR_SSID]) {
	5527	+ n_match_sets++;
	5528	+ continue;
	5529	+ }
	5530	+ rssi = tb[NL80211_SCHED_SCAN_MATCH_ATTR_RSSI];
	5531	+ if (rssi)
	5532	+ default_match_rssi = nla_get_s32(rssi);
	5533	+ }
	5534	+ }
	5535	+
	5536	+ /* However, if there's no other matchset, add the RSSI one */
	5537	+ if (!n_match_sets && default_match_rssi != NL80211_SCAN_RSSI_THOLD_OFF)
	5538	+ n_match_sets = 1;
5509	5539
5510	5540	if (n_match_sets > wiphy->max_match_sets)
5511	5541	return -EINVAL;
@@ -5633,6 +5663,15 @@ static int nl80211_start_sched_scan(struct sk_buff *skb, · 121 unmodified lines
5633	5663	goto out_free;
5634	5664	ssid = tb[NL80211_SCHED_SCAN_MATCH_ATTR_SSID];
5635	5665	if (ssid) {
	5666	+ if (WARN_ON(i >= n_match_sets)) {
	5667	+ /* this indicates a programming error,
	5668	+ * the loop above should have verified
	5669	+ * things properly
	5670	+ */
	5671	+ err = -EINVAL;
	5672	+ goto out_free;
	5673	+ }
	5674	+
5636	5675	if (nla_len(ssid) > IEEE80211_MAX_SSID_LEN) {
5637	5676	err = -EINVAL;
5638	5677	goto out_free;
@@ -5641,15 +5680,28 @@ static int nl80211_start_sched_scan(struct sk_buff *skb, · 2 unmodified lines
5641	5680	nla_data(ssid), nla_len(ssid));
5642	5681	request->match_sets[i].ssid.ssid_len =
5643	5682	nla_len(ssid);
	5683	+ /* special attribute - old implemenation w/a */
	5684	+ request->match_sets[i].rssi_thold =
	5685	+ default_match_rssi;
	5686	+ rssi = tb[NL80211_SCHED_SCAN_MATCH_ATTR_RSSI];
	5687	+ if (rssi)
	5688	+ request->match_sets[i].rssi_thold =
	5689	+ nla_get_s32(rssi);
5644	5690	}
5645		− rssi = tb[NL80211_SCHED_SCAN_MATCH_ATTR_RSSI];
5646		− if (rssi)
5647		− request->rssi_thold = nla_get_u32(rssi);
5648		− else
5649		− request->rssi_thold =
5650		− NL80211_SCAN_RSSI_THOLD_OFF;
5651	5691	i++;
5652	5692	}
	5693	+
	5694	+ /* there was no other matchset, so the RSSI one is alone */
	5695	+ if (i == 0)
	5696	+ request->match_sets[0].rssi_thold = default_match_rssi;
	5697	+
	5698	+ request->min_rssi_thold = INT_MAX;
	5699	+ for (i = 0; i < n_match_sets; i++)
	5700	+ request->min_rssi_thold =
	5701	+ min(request->match_sets[i].rssi_thold,
	5702	+ request->min_rssi_thold);
	5703	+ } else {
	5704	+ request->min_rssi_thold = NL80211_SCAN_RSSI_THOLD_OFF;
5653	5705	}
5654	5706
5655	5707	if (info->attrs[NL80211_ATTR_IE]) {