[RFC 3/3] mac80211: Add receive path for ethernet frame format

[Vasanthakumar Thiagarajan <vthiagar@qti.qualcomm.com>]

Implement rx path which does fewer processing on the
received data frame which has already gone through
802.11 header decapsulation and other functionalities
which require 802.11 header in the low level driver
or hardware. Currently this rx path is restricted
to AP and STA mode, but can be extended for Adhoc
mode as well.

This rx path only checks if the driver has advertised
it's support of 802.11 header encap/decap offload for
data frames. It is upto the low level driver to make
sure if the frame that it passes is in ethernet format
and the sta pointer is valid.

Signed-off-by: Vasanthakumar Thiagarajan <vthiagar@qti.qualcomm.com>
---
 include/net/mac80211.h |  19 +++++
 net/mac80211/rx.c      | 189 ++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 206 insertions(+), 2 deletions(-)

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 225abaa..75c55e2 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1088,6 +1088,9 @@ ieee80211_tx_info_clear_status(struct ieee80211_tx_info *info)
  * @RX_FLAG_ALLOW_SAME_PN: Allow the same PN as same packet before.
  *	This is used for AMSDU subframes which can have the same PN as
  *	the first subframe.
+ * @RX_FLAG_MCAST: If the receiver address (addr1) in the frame is multicast.
+ *	This is used with the data frames by the drivers supporting 802.11 hdr
+ *	decap offload.
  */
 enum mac80211_rx_flags {
 	RX_FLAG_MMIC_ERROR		= BIT(0),
@@ -1123,6 +1126,7 @@ enum mac80211_rx_flags {
 	RX_FLAG_RADIOTAP_VENDOR_DATA	= BIT(31),
 	RX_FLAG_MIC_STRIPPED		= BIT_ULL(32),
 	RX_FLAG_ALLOW_SAME_PN		= BIT_ULL(33),
+	RX_FLAG_MCAST			= BIT_ULL(34),
 };
 
 #define RX_FLAG_STBC_SHIFT		26
@@ -3989,6 +3993,21 @@ static inline void ieee80211_rx_ni(struct ieee80211_hw *hw,
 }
 
 /**
+ * ieee80211_rx_decap_offl - Receive frames in 802.11 decapsulated format
+ *
+ * Low level driver capable of 802.11 header decap uses this function. The frame
+ * will be in ethernet format.
+ * This function may not be called in IRQ context. Calls to this function
+ * for a single hardware must be synchronized against each other.
+ *
+ * @hw: the hardware this frame came in on
+ * @sta : the station the frame was received from, must not be %NULL
+ * @skb: the buffer to receive, owned by mac80211 after this call
+ */
+void ieee80211_rx_decap_offl(struct ieee80211_hw *hw, struct ieee80211_sta *sta,
+			     struct sk_buff *skb);
+
+/**
  * ieee80211_sta_ps_transition - PS transition for connected sta
  *
  * When operating in AP mode with the %IEEE80211_HW_AP_LINK_PS
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 2e8a902..3cb8d6e 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2103,13 +2103,14 @@ __ieee80211_data_to_8023(struct ieee80211_rx_data *rx, bool *port_control)
 	return 0;
 }
 
+static const u8 pae_group_addr[ETH_ALEN] __aligned(2)
+	= { 0x01, 0x80, 0xC2, 0x00, 0x00, 0x03 };
+
 /*
  * requires that rx->skb is a frame with ethernet header
  */
 static bool ieee80211_frame_allowed(struct ieee80211_rx_data *rx, __le16 fc)
 {
-	static const u8 pae_group_addr[ETH_ALEN] __aligned(2)
-		= { 0x01, 0x80, 0xC2, 0x00, 0x00, 0x03 };
 	struct ethhdr *ehdr = (struct ethhdr *) rx->skb->data;
 
 	/*
@@ -4180,3 +4181,187 @@ void ieee80211_rx_irqsafe(struct ieee80211_hw *hw, struct sk_buff *skb)
 	tasklet_schedule(&local->tasklet);
 }
 EXPORT_SYMBOL(ieee80211_rx_irqsafe);
+
+/* Receive path for decap offloaded data frames */
+
+static void
+ieee80211_rx_handle_decap_offl(struct ieee80211_sub_if_data *sdata,
+				     struct sta_info *sta, struct sk_buff *skb)
+{
+	struct ieee80211_local *local = sdata->local;
+	struct ieee80211_vif *vif = &sdata->vif;
+	struct net_device *dev = sdata->dev;
+	struct ieee80211_rx_status *status;
+	struct ieee80211_key *key = NULL;
+	struct ieee80211_rx_data rx;
+	int i;
+	struct ethhdr *ehdr;
+
+	ehdr = (struct ethhdr *)skb->data;
+	status = IEEE80211_SKB_RXCB(skb);
+
+	/* TODO: Extend ieee80211_rx_decap_offl() with bssid so that Ethernet
+	 * encap/decap can be supported in Adhoc interface type as well.
+	 * Adhoc interface depends on bssid to udpate last_rx.
+	 */
+	if (vif->type != NL80211_IFTYPE_STATION &&
+	    vif->type != NL80211_IFTYPE_AP_VLAN &&
+	    vif->type != NL80211_IFTYPE_AP)
+		goto drop;
+
+	I802_DEBUG_INC(local->dot11ReceivedFragmentCount);
+
+	if (!(status->flag & RX_FLAG_MCAST)) {
+		sta->rx_stats.last_rx = jiffies;
+		sta->rx_stats.last_rate = sta_stats_encode_rate(status);
+	}
+
+	if (sdata->vif.type == NL80211_IFTYPE_STATION &&
+	    !is_multicast_ether_addr(ehdr->h_dest))
+		ieee80211_sta_reset_conn_monitor(sdata);
+
+	sta->rx_stats.fragments++;
+
+	u64_stats_update_begin(&sta->rx_stats.syncp);
+	sta->rx_stats.bytes += skb->len;
+	u64_stats_update_end(&sta->rx_stats.syncp);
+
+	if (!(status->flag & RX_FLAG_NO_SIGNAL_VAL)) {
+		sta->rx_stats.last_signal = status->signal;
+		ewma_signal_add(&sta->rx_stats_avg.signal, -status->signal);
+	}
+
+	if (status->chains) {
+		sta->rx_stats.chains = status->chains;
+		for (i = 0; i < ARRAY_SIZE(status->chain_signal); i++) {
+			int signal = status->chain_signal[i];
+
+			if (!(status->chains & BIT(i)))
+				continue;
+
+			sta->rx_stats.chain_signal_last[i] = signal;
+			ewma_signal_add(&sta->rx_stats_avg.chain_signal[i],
+					-signal);
+		}
+	}
+
+	if (status->flag & RX_FLAG_MCAST) {
+		for (i = 0; i < NUM_DEFAULT_KEYS; i++) {
+			key = rcu_dereference(sta->gtk[i]);
+			if (key)
+				break;
+		}
+	} else {
+		key = rcu_dereference(sta->ptk[sta->ptk_idx]);
+	}
+
+	if (key && unlikely(key->flags & KEY_FLAG_TAINTED))
+		goto drop;
+
+	if (status->flag & RX_FLAG_MMIC_ERROR) {
+		if (key)
+			key->u.tkip.mic_failures++;
+		goto mic_fail;
+	}
+
+	if (unlikely(!test_sta_flag(sta, WLAN_STA_AUTHORIZED))) {
+		if (ehdr->h_proto != sdata->control_port_protocol)
+			goto drop;
+		else if (!ether_addr_equal(ehdr->h_dest, vif->addr) &&
+			 !ether_addr_equal(ehdr->h_dest, pae_group_addr))
+			goto drop;
+	}
+
+	if (unlikely(ehdr->h_proto == cpu_to_be16(ETH_P_TDLS))) {
+		struct ieee80211_tdls_data *tf = (void *)skb->data;
+
+		if (pskb_may_pull(skb,
+				  offsetof(struct ieee80211_tdls_data, u)) &&
+		    tf->payload_type == WLAN_TDLS_SNAP_RFTYPE &&
+		    tf->category == WLAN_CATEGORY_TDLS &&
+		    (tf->action_code == WLAN_TDLS_CHANNEL_SWITCH_REQUEST ||
+		     tf->action_code == WLAN_TDLS_CHANNEL_SWITCH_RESPONSE)) {
+			skb_queue_tail(&local->skb_queue_tdls_chsw, skb);
+			schedule_work(&local->tdls_chsw_work);
+			sta->rx_stats.packets++;
+			return;
+		}
+	}
+
+	memset(&rx, 0, sizeof(rx));
+	rx.skb = skb;
+	rx.sdata = sdata;
+	rx.local = local;
+	rx.sta = sta;
+
+	if (vif->type == NL80211_IFTYPE_AP_VLAN && sdata->bss &&
+	    unlikely(ehdr->h_proto == sdata->control_port_protocol)) {
+		sdata = container_of(sdata->bss, struct ieee80211_sub_if_data,
+				     u.ap);
+		dev = sdata->dev;
+		rx.sdata = sdata;
+	}
+
+	rx.skb->dev = dev;
+
+	/* XXX: Since rx.seqno_idx is not available for decap offloaded frames
+	 * rx msdu stats update at the seqno_idx in ieee80211_deliver_skb()
+	 * will always be updated at index 0 and will not be very useful.
+	 */
+	ieee80211_deliver_skb(&rx);
+
+	return;
+
+mic_fail:
+	cfg80211_michael_mic_failure(sdata->dev, sta->addr,
+				     (status->flag & RX_FLAG_MCAST) ?
+				     NL80211_KEYTYPE_GROUP :
+				     NL80211_KEYTYPE_PAIRWISE,
+				     key ? key->conf.keyidx : -1,
+				     NULL, GFP_ATOMIC);
+
+drop:
+	sta->rx_stats.dropped++;
+	dev_kfree_skb(skb);
+}
+
+/* Receive path handler that a low level driver supporting 802.11 hdr decap
+ * offload can call. The frame is in ethernet format and the assumption is
+ * all necessary operations like decryption, defrag, deaggregation, etc.
+ * requiring 802.11 headers are already performed in the low level driver
+ * or hardware.
+ */
+void ieee80211_rx_decap_offl(struct ieee80211_hw *hw,
+			     struct ieee80211_sta *pubsta, struct sk_buff *skb)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+	struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
+
+	if (unlikely(local->quiescing || local->suspended))
+		goto drop;
+
+	if (unlikely(local->in_reconfig))
+		goto drop;
+
+	if (WARN_ON(!local->started))
+		goto drop;
+
+	/* TODO: Sanity checks on flags/rx_flags like done in
+	 * ieee80211_invoke_fast_rx() to confirm if the frame
+	 * has gone through all the functionalities which require
+	 * 802.11 frame header.
+	 */
+
+	rcu_read_lock();
+
+	/* TODO: Toggle Rx throughput LED */
+
+	ieee80211_rx_handle_decap_offl(sta->sdata, sta, skb);
+
+	rcu_read_unlock();
+
+	return;
+drop:
+	kfree_skb(skb);
+}
+EXPORT_SYMBOL(ieee80211_rx_decap_offl);
-- 
1.9.1