[RFC] mac80211: avoid reflecting frames back to the client

Commit Message

Johannes Berg Sept. 26, 2018, 5:28 p.m. UTC

From: Johannes Berg <[e-mail]>

I'm not really sure exactly _why_ I've been carrying a note
for what's probably _years_ to check that we don't do this,
but we clearly do reflect frames back to the station itself
if it sends such.

One way or the other, it's useless since the station doesn't
really need the AP to talk to itself, so suppress it.

While at it, clarify some of the logic by removing skb->data
references in favour of the destination address (pointer) we
already have separately.

Signed-off-by: Johannes Berg <[e-mail]>
---
Jouni, maybe you remember why?
---
 net/mac80211/rx.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

Patch

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 96611d5dfadb..9d93d60d0635 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2425,8 +2425,9 @@  ieee80211_deliver_skb(struct ieee80211_rx_data *rx)
 			if (!xmit_skb)
 				net_info_ratelimited("%s: failed to clone multicast frame\n",
 						    dev->name);
-		} else if (!is_multicast_ether_addr(ehdr->h_dest)) {
-			dsta = sta_info_get(sdata, skb->data);
+		} else if (!is_multicast_ether_addr(ehdr->h_dest) &&
+			   !ether_addr_equal(ehdr->h_dest, ehdr->h_source)) {
+			dsta = sta_info_get(sdata, ehdr->h_dest);
 			if (dsta) {
 				/*
 				 * The destination station is associated to
@@ -4207,11 +4208,10 @@  static bool ieee80211_invoke_fast_rx(struct ieee80211_rx_data *rx,
 
 	if (fast_rx->internal_forward) {
 		struct sk_buff *xmit_skb = NULL;
-		bool multicast = is_multicast_ether_addr(skb->data);
-
-		if (multicast) {
+		if (is_multicast_ether_addr(addrs.da)) {
 			xmit_skb = skb_copy(skb, GFP_ATOMIC);
-		} else if (sta_info_get(rx->sdata, skb->data)) {
+		} else if (!ether_addr_equal(addrs.da, addrs.sa) &&
+			   sta_info_get(rx->sdata, addrs.da)) {
 			xmit_skb = skb;
 			skb = NULL;
 		}