[PATCH v2 10/22] cfg80211: convert S1G beacon to scan results

Thomas Pedersen
2020-08-31T20:56:28Z

The S1G beacon is an extension frame as opposed to
management frame for the regular beacon. This means we may
have to occasionally cast the frame buffer to a different
header type. Luckily this isn't too bad as scan results
mostly only care about the IEs.

Signed-off-by: Thomas Pedersen <thomas@adapt-ip.com>
---
include/linux/ieee80211.h | 32 ++++++++++++++++++++++
net/wireless/scan.c | 57 ++++++++++++++++++++++++++++++++-------
2 files changed, 80 insertions(+), 9 deletions(-)

diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index 53fba39d4ba6..bca4bb443291 100644
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -151,6 +151,9 @@

#define IEEE80211_ANO_NETTYPE_WILD 15

+/* bits unique to S1G beacon */
+#define IEEE80211_S1G_BCN_NEXT_TBTT 0x100
+
/* control extension - for IEEE80211_FTYPE_CTL | IEEE80211_STYPE_CTL_EXT */
#define IEEE80211_CTL_EXT_POLL 0x2000
#define IEEE80211_CTL_EXT_SPR 0x3000
@@ -553,6 +556,28 @@ static inline bool ieee80211_is_s1g_beacon(__le16 fc)
cpu_to_le16(IEEE80211_FTYPE_EXT | IEEE80211_STYPE_S1G_BEACON);
}

+/**
+ * ieee80211_next_tbtt_present - check if IEEE80211_FTYPE_EXT &&
+ * IEEE80211_STYPE_S1G_BEACON && IEEE80211_S1G_BCN_NEXT_TBTT
+ * @fc: frame control bytes in little-endian byteorder
+ */
+static inline bool ieee80211_next_tbtt_present(__le16 fc)
+{
+ return (fc & cpu_to_le16(IEEE80211_FCTL_FTYPE | IEEE80211_FCTL_STYPE)) ==
+ cpu_to_le16(IEEE80211_FTYPE_EXT | IEEE80211_STYPE_S1G_BEACON) &&
+ fc & cpu_to_le16(IEEE80211_S1G_BCN_NEXT_TBTT);
+}
+
+/**
+ * ieee80211_is_s1g_short_beacon - check if next tbtt present bit is set. Only
+ * true for S1G beacons when they're short.
+ * @fc: frame control bytes in little-endian byteorder
+ */
+static inline bool ieee80211_is_s1g_short_beacon(__le16 fc)
+{
+ return ieee80211_is_s1g_beacon(fc) && ieee80211_next_tbtt_present(fc);
+}
+
/**
* ieee80211_is_atim - check if IEEE80211_FTYPE_MGMT && IEEE80211_STYPE_ATIM
* @fc: frame control bytes in little-endian byteorder
@@ -1034,6 +1059,13 @@ struct ieee80211_ext {
u8 change_seq;
u8 variable[0];
} __packed s1g_beacon;
+ struct {
+ u8 sa[ETH_ALEN];
+ __le32 timestamp;
+ u8 change_seq;
+ u8 next_tbtt[3];
+ u8 variable[0];
+ } __packed s1g_short_beacon;
} u;
} __packed __aligned(2);

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 84fc8ab16dd2..b4c85e8f2107 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -1807,8 +1807,11 @@ cfg80211_inform_single_bss_frame_data(struct wiphy *wiphy,
struct cfg80211_bss_ies *ies;
struct ieee80211_channel *channel;
bool signal_valid;
- size_t ielen = len - offsetof(struct ieee80211_mgmt,
- u.probe_resp.variable);
+ struct ieee80211_ext *ext = NULL;
+ u8 *bssid, *variable;
+ u16 capability, beacon_int;
+ size_t ielen, min_hdr_len = offsetof(struct ieee80211_mgmt,
+ u.probe_resp.variable);
int bss_type;

BUILD_BUG_ON(offsetof(struct ieee80211_mgmt, u.probe_resp.variable) !=
@@ -1826,21 +1829,57 @@ cfg80211_inform_single_bss_frame_data(struct wiphy *wiphy,
(data->signal < 0 || data->signal > 100)))
return NULL;

- if (WARN_ON(len < offsetof(struct ieee80211_mgmt, u.probe_resp.variable)))
+ if (ieee80211_is_s1g_beacon(mgmt->frame_control)) {
+ ext = (void *) mgmt;
+ min_hdr_len = offsetof(struct ieee80211_ext, u.s1g_beacon);
+ if (ieee80211_is_s1g_short_beacon(mgmt->frame_control))
+ min_hdr_len = offsetof(struct ieee80211_ext,
+ u.s1g_short_beacon.variable);
+ }
+
+ if (WARN_ON(len < min_hdr_len))
return NULL;

- channel = cfg80211_get_bss_channel(wiphy, mgmt->u.beacon.variable,
+ ielen = len - min_hdr_len;
+ variable = mgmt->u.probe_resp.variable;
+ if (ext) {
+ if (ieee80211_is_s1g_short_beacon(mgmt->frame_control))
+ variable = ext->u.s1g_short_beacon.variable;
+ else
+ variable = ext->u.s1g_beacon.variable;
+ }
+
+ channel = cfg80211_get_bss_channel(wiphy, variable,
ielen, data->chan, data->scan_width);
if (!channel)
return NULL;

+ if (ext) {
+ struct ieee80211_s1g_bcn_compat_ie *compat;
+ u8 *ie;
+
+ ie = (void *)cfg80211_find_ie(WLAN_EID_S1G_BCN_COMPAT,
+ variable, ielen);
+ if (!ie)
+ return NULL;
+ compat = (void *)(ie + 2);
+ bssid = ext->u.s1g_beacon.sa;
+ capability = le16_to_cpu(compat->compat_info);
+ beacon_int = le16_to_cpu(compat->beacon_int);
+ } else {
+ bssid = mgmt->bssid;
+ beacon_int = le16_to_cpu(mgmt->u.probe_resp.beacon_int);
+ capability = le16_to_cpu(mgmt->u.probe_resp.capab_info);
+ }
+
ies = kzalloc(sizeof(*ies) + ielen, gfp);
if (!ies)
return NULL;
ies->len = ielen;
ies->tsf = le64_to_cpu(mgmt->u.probe_resp.timestamp);
- ies->from_beacon = ieee80211_is_beacon(mgmt->frame_control);
- memcpy(ies->data, mgmt->u.probe_resp.variable, ielen);
+ ies->from_beacon = ieee80211_is_beacon(mgmt->frame_control) ||
+ ieee80211_is_s1g_beacon(mgmt->frame_control);
+ memcpy(ies->data, variable, ielen);

if (ieee80211_is_probe_resp(mgmt->frame_control))
rcu_assign_pointer(tmp.pub.proberesp_ies, ies);
@@ -1848,12 +1887,12 @@ cfg80211_inform_single_bss_frame_data(struct wiphy *wiphy,
rcu_assign_pointer(tmp.pub.beacon_ies, ies);
rcu_assign_pointer(tmp.pub.ies, ies);

- memcpy(tmp.pub.bssid, mgmt->bssid, ETH_ALEN);
+ memcpy(tmp.pub.bssid, bssid, ETH_ALEN);
+ tmp.pub.beacon_interval = beacon_int;
+ tmp.pub.capability = capability;
tmp.pub.channel = channel;
tmp.pub.scan_width = data->scan_width;
tmp.pub.signal = data->signal;
- tmp.pub.beacon_interval = le16_to_cpu(mgmt->u.probe_resp.beacon_int);
- tmp.pub.capability = le16_to_cpu(mgmt->u.probe_resp.capab_info);
tmp.ts_boottime = data->boottime_ns;
tmp.parent_tsf = data->parent_tsf;
tmp.pub.chains = data->chains;
--
2.20.1