Subject: [PATCH v2] mac80211: add missing WFA Multi-AP backhaul STA Rx requirement

The current mac80211 WDS (4-address mode) can be used to cover most of the
Multi-AP requirements for Data frames per the WFA Multi-AP Specification v1.0.
When configuring AP/STA interfaces in 4-address mode, they are able to function
as fronthaul AP/backhaul STA of Multi-AP device complying below
Tx, Rx requirements except one missing STA Rx requirement added by this patch.

Multi-AP specification section 14.1 describes the following requirements:

Transmitter requirements
------------------------
1. Fronthaul AP
i) When DA!=RA of backhaul STA, must use 4-address format
ii) When DA==RA of backhaul STA, shall use either 3-address
or 4-address format with RA updated with STA MAC

(mac80211 support 4-address format via AP/VLAN interface)

2. Backhaul STA
i) When SA!=TA of backhaul STA, must use 4-address format
ii) When SA==TA of backhaul STA, shall use either 3-address
or 4-address format with RA updated with AP MAC

(mac80211 support 4-address format via use_4addr)

Receiver requirements
---------------------
1. Fronthaul AP
i) When SA!=TA of backhaul STA, must support receiving 4-address
format frames
ii) When SA==TA of backhaul STA, must support receiving both
3-address and 4-address format frames

(mac80211 support both 3-addr & 4-addr via AP/VLAN interface)

2. Backhaul STA
i) When DA!=RA of backhaul STA, must support receiving 4-address
format frames
ii) When DA==RA of backhaul STA, must support receiving both
3-address and 4-address format frames

(mac80211 support only receiving 4-address format via
use_4addr)

This patch addresses the above Rx requirement (ii) for backhaul STA to receive
unicast (DA==RA) 3-address frames in addition to 4-address frames.

The current design doesn't accept 3-address frames when configured in 4-address
mode (use_4addr). Hence add a check to allow 3-address frames when DA==RA of
backhaul STA (adhering to Table 9-26 of IEEE Std 802.11™-2016).

This case was tested with a bridged station interface when associated with
a non-mac80211 based vendor AP implementation using 3-address frames for WDS.

STA was able to support the Multi-AP Rx requirement when DA==RA. No issues,
no loops seen when tested with mac80211 based AP as well.

Verified and confirmed all other Tx and Rx requirements of AP and STA for
Multi-AP respectively. They all work using the current mac80211-WDS design.

Signed-off-by: Sathishkumar Muruganandam <[email protected]>
---
Changes in v2:
* Changed subject title
* Cleaned up commit log
---
net/mac80211/rx.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 64742f2765c4..134bbbc9cd6e 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2313,7 +2313,7 @@ __ieee80211_data_to_8023(struct ieee80211_rx_data *rx, bool *port_control)

if (!sdata->u.mgd.use_4addr)
return -1;
- else
+ else if (!ether_addr_equal(hdr->addr1, sdata->vif.addr))
check_port_control = true;
}

--
2.17.1