[PATCH 7/7] mac80211: implement support for yet another mesh A-MSDU format

[Felix Fietkau <nbd@nbd.name>]

MT7996 hardware supports mesh A-MSDU subframes in hardware, but uses a
big-endian length field

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
---
 include/net/cfg80211.h  | 11 +++++++----
 net/mac80211/rx.c       | 22 ++++++++++++++++------
 net/mac80211/sta_info.h |  5 ++++-
 net/wireless/util.c     | 36 +++++++++++++++++++++++-------------
 4 files changed, 50 insertions(+), 24 deletions(-)

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 7cebba1c4135..86cb048dc924 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -6274,10 +6274,13 @@ static inline int ieee80211_data_to_8023(struct sk_buff *skb, const u8 *addr,
  * mesh control field.
  *
  * @skb: The input A-MSDU frame without any headers.
- * @mesh_hdr: use standard compliant mesh A-MSDU subframe header
+ * @mesh_hdr: the type of mesh header to test
+ *	0: non-mesh A-MSDU length field
+ *	1: big-endian mesh A-MSDU length field
+ *	2: little-endian mesh A-MSDU length field
  * Returns: true if subframe header lengths are valid for the @mesh_hdr mode
  */
-bool ieee80211_is_valid_amsdu(struct sk_buff *skb, bool mesh_hdr);
+bool ieee80211_is_valid_amsdu(struct sk_buff *skb, u8 mesh_hdr);
 
 /**
  * ieee80211_amsdu_to_8023s - decode an IEEE 802.11n A-MSDU frame
@@ -6294,13 +6297,13 @@ bool ieee80211_is_valid_amsdu(struct sk_buff *skb, bool mesh_hdr);
  * @extra_headroom: The hardware extra headroom for SKBs in the @list.
  * @check_da: DA to check in the inner ethernet header, or NULL
  * @check_sa: SA to check in the inner ethernet header, or NULL
- * @mesh_control: A-MSDU subframe header includes the mesh control field
+ * @mesh_control: see mesh_hdr in ieee80211_is_valid_amsdu
  */
 void ieee80211_amsdu_to_8023s(struct sk_buff *skb, struct sk_buff_head *list,
 			      const u8 *addr, enum nl80211_iftype iftype,
 			      const unsigned int extra_headroom,
 			      const u8 *check_da, const u8 *check_sa,
-			      bool mesh_control);
+			      u8 mesh_control);
 
 /**
  * ieee80211_get_8023_tunnel_proto - get RFC1042 or bridge tunnel encap protocol
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 2a883d956260..3635d036375a 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2983,13 +2983,23 @@ __ieee80211_rx_h_amsdu(struct ieee80211_rx_data *rx, u8 data_offset)
 		return RX_DROP_UNUSABLE;
 
 	if (rx->sta && rx->sta->amsdu_mesh_control < 0) {
-		bool valid_std = ieee80211_is_valid_amsdu(skb, true);
-		bool valid_nonstd = ieee80211_is_valid_amsdu(skb, false);
+		s8 valid = -1;
+		int i;
+
+		for (i = 0; i <= 2; i++) {
+			if (!ieee80211_is_valid_amsdu(skb, i))
+				continue;
+
+			if (valid >= 0) {
+				/* ambiguous */
+				valid = -1;
+				break;
+			}
+
+			valid = i;
+		}
 
-		if (valid_std && !valid_nonstd)
-			rx->sta->amsdu_mesh_control = 1;
-		else if (valid_nonstd && !valid_std)
-			rx->sta->amsdu_mesh_control = 0;
+		rx->sta->amsdu_mesh_control = valid;
 	}
 
 	ieee80211_amsdu_to_8023s(skb, &frame_list, dev->dev_addr,
diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index e8e482a82d77..f354d470e174 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -623,7 +623,10 @@ struct link_sta_info {
  * @cparams: CoDel parameters for this station.
  * @reserved_tid: reserved TID (if any, otherwise IEEE80211_TID_UNRESERVED)
  * @amsdu_mesh_control: track the mesh A-MSDU format used by the peer
- *	(-1: not yet known, 0: non-standard [without mesh header], 1: standard)
+ *	(-1: not yet known,
+ *	  0: non-mesh A-MSDU length field
+ *	  1: big-endian mesh A-MSDU length field
+ *	  2: little-endian mesh A-MSDU length field)
  * @fast_tx: TX fastpath information
  * @fast_rx: RX fastpath information
  * @tdls_chandef: a TDLS peer can have a wider chandef that is compatible to
diff --git a/net/wireless/util.c b/net/wireless/util.c
index d1a89e82ead0..3bc0c3072e78 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -776,7 +776,24 @@ __ieee80211_amsdu_copy(struct sk_buff *skb, unsigned int hlen,
 	return frame;
 }
 
-bool ieee80211_is_valid_amsdu(struct sk_buff *skb, bool mesh_hdr)
+static u16
+ieee80211_amsdu_subframe_length(void *field, u8 mesh_flags, u8 hdr_type)
+{
+	__le16 *field_le = field;
+	__be16 *field_be = field;
+	u16 len;
+
+	if (hdr_type >= 2)
+		len = le16_to_cpu(*field_le);
+	else
+		len = be16_to_cpu(*field_be);
+	if (hdr_type)
+		len += __ieee80211_get_mesh_hdrlen(mesh_flags);
+
+	return len;
+}
+
+bool ieee80211_is_valid_amsdu(struct sk_buff *skb, u8 mesh_hdr)
 {
 	int offset = 0, remaining, subframe_len, padding;
 
@@ -790,12 +807,8 @@ bool ieee80211_is_valid_amsdu(struct sk_buff *skb, bool mesh_hdr)
 		if (skb_copy_bits(skb, offset + 2 * ETH_ALEN, &hdr, sizeof(hdr)) < 0)
 			return false;
 
-		if (mesh_hdr)
-			len = le16_to_cpu(*(__le16 *)&hdr.len) +
-			      __ieee80211_get_mesh_hdrlen(hdr.mesh_flags);
-		else
-			len = ntohs(hdr.len);
-
+		len = ieee80211_amsdu_subframe_length(&hdr.len, hdr.mesh_flags,
+						      mesh_hdr);
 		subframe_len = sizeof(struct ethhdr) + len;
 		padding = (4 - subframe_len) & 0x3;
 		remaining = skb->len - offset;
@@ -812,7 +825,7 @@ void ieee80211_amsdu_to_8023s(struct sk_buff *skb, struct sk_buff_head *list,
 			      const u8 *addr, enum nl80211_iftype iftype,
 			      const unsigned int extra_headroom,
 			      const u8 *check_da, const u8 *check_sa,
-			      bool mesh_control)
+			      u8 mesh_control)
 {
 	unsigned int hlen = ALIGN(extra_headroom, 4);
 	struct sk_buff *frame = NULL;
@@ -837,11 +850,8 @@ void ieee80211_amsdu_to_8023s(struct sk_buff *skb, struct sk_buff_head *list,
 		skb_copy_bits(skb, offset, &hdr, copy_len);
 		if (iftype == NL80211_IFTYPE_MESH_POINT)
 			mesh_len = __ieee80211_get_mesh_hdrlen(hdr.flags);
-		if (mesh_control)
-			len = le16_to_cpu(*(__le16 *)&hdr.eth.h_proto) + mesh_len;
-		else
-			len = ntohs(hdr.eth.h_proto);
-
+		len = ieee80211_amsdu_subframe_length(&hdr.eth.h_proto, hdr.flags,
+						      mesh_control);
 		subframe_len = sizeof(struct ethhdr) + len;
 		padding = (4 - subframe_len) & 0x3;
 
-- 
2.39.0