[ath9k-devel] Dropped frames (unauthorized port) in AP mode

Mihai Moldovan ionic at ionic.de
Thu Jun 20 23:12:55 EDT 2013


* On 18.06.2013 11:25 PM, Mihai Moldovan wrote:
> [...]
> Looking at the kernel source (net/mac80211/tx.c), this condition is being triggered:
>
> if (unlikely(!ieee80211_vif_is_mesh(&sdata->vif) &&
>                      !is_multicast_ether_addr(hdr.addr1) && !authorized &&
>                      (cpu_to_be16(ethertype) != sdata->control_port_protocol ||
>                       !ether_addr_equal(sdata->vif.addr, skb->data + ETH_ALEN))))

Fugly print-debugged this statement, and I'm heavily confused.

The subcondition "cpu_to_be16(ethertype) != sdata->control_port_protocol" is
true for me!

Thus, I checked "sdata->control_port_protocol", which is ETH_P_PAE (0x888E)...
i.e., 802.1X. Great for WiFi authentication.

"ethertype", on the other hand, is ETH_P_DDCMP (0x0006) which left me totally
confused! How is this possible? ethertype should ideally also be ETH_P_PAE,
definitely not some only internally used DECnet port protocol.

Yes, CONFIG_DECNET is turned on in my kernel config, but I'm not (actively) even
using DECnet.

ethertype is set from the socket buffer's data (ethertype = (skb->data[12] << 8)
| skb->data[13]), but what is generating this packet? If the ethertype fetching
is actually correct in net/mac80211/tx.c, what would ever set it to 0x0006?

CCing Johannes Berg, as git is "blaming" him for those line(s) (originally Jiri
Benc, but I haven't seen list posts in a while, assuming he's not maintaining
anymore.)

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