Rafał Miłecki
2018-Feb-27 10:14 UTC
[Bridge] Problem with bridge (mcast-to-ucast + hairpin) and Broadcom's 802.11f in their FullMAC fw
Sending with a fixed linux-wireless ML address. Please kindly send your replies using linux-wireless@ On 02/27/2018 11:08 AM, Rafa? Mi?ecki wrote:> I've problem when using OpenWrt/LEDE on a home router with Broadcom's > FullMAC WiFi chipset. > > > First of all OpenWrt/LEDE uses bridge interface for LAN network with: > 1) IFLA_BRPORT_MCAST_TO_UCAST > 2) Clients isolation in hostapd > 3) Hairpin mode enabled > > For more details please see Linus's patch description: > https://patchwork.kernel.org/patch/9530669/ > and maybe hairpin mode patch: > https://lwn.net/Articles/347344/ > > Short version: in that setup packets received from a bridged wireless > interface can be handled back to it for transmission. > > > Now, Broadcom's firmware for their FullMAC chipsets in AP mode > supports an obsoleted 802.11f AKA IAPP standard. It's a roaming > standard that was replaced by 802.11r. > > Whenever a new station associates, firmware generates a packet like: > ff ff ff ff ff ff ec 10 7b 5f ?? ?? 00 06 00 01 af 81 01 00 > (just masked 2 bytes of my MAC) > > For mode details you can see discussion in my brcmfmac patch thread: > https://patchwork.kernel.org/patch/10191451/ > > > The problem is that bridge (in setup as above) handles such a packet > back to the device. > > That makes Broadcom's FullMAC firmware believe that a given station > just connected to another AP in a network (which doesn't even exist). > As a result firmware immediately disassociates that station. It's > simply impossible to connect to the router. Every association is > followed by immediate disassociation. > > > Can you see any solution for this problem? Is that an option to stop > multicast-to-unicast from touching 802.11f packets? Some other ideas? > Obviously I can't modify Broadcom's firmware and drop that obsoleted > standard.
Arend van Spriel
2018-Feb-28 11:31 UTC
[Bridge] Problem with bridge (mcast-to-ucast + hairpin) and Broadcom's 802.11f in their FullMAC fw
On 2/27/2018 11:14 AM, Rafa? Mi?ecki wrote:> Sending with a fixed linux-wireless ML address. Please kindly send your > replies using linux-wireless@ > > On 02/27/2018 11:08 AM, Rafa? Mi?ecki wrote: >> I've problem when using OpenWrt/LEDE on a home router with Broadcom's >> FullMAC WiFi chipset. >> >> >> First of all OpenWrt/LEDE uses bridge interface for LAN network with: >> 1) IFLA_BRPORT_MCAST_TO_UCAST >> 2) Clients isolation in hostapd >> 3) Hairpin mode enabled >> >> For more details please see Linus's patch description: >> https://patchwork.kernel.org/patch/9530669/ >> and maybe hairpin mode patch: >> https://lwn.net/Articles/347344/ >> >> Short version: in that setup packets received from a bridged wireless >> interface can be handled back to it for transmission. >> >> >> Now, Broadcom's firmware for their FullMAC chipsets in AP mode >> supports an obsoleted 802.11f AKA IAPP standard. It's a roaming >> standard that was replaced by 802.11r. >> >> Whenever a new station associates, firmware generates a packet like: >> ff ff ff ff ff ff ec 10 7b 5f ?? ?? 00 06 00 01 af 81 01 00 >> (just masked 2 bytes of my MAC) >> >> For mode details you can see discussion in my brcmfmac patch thread: >> https://patchwork.kernel.org/patch/10191451/ >> >> >> The problem is that bridge (in setup as above) handles such a packet >> back to the device.From reading the referenced links I understand the hairpin mode is causing the packet to be sent back to the device, and the hairpin mode is required for MCAST_TO_UCAST, right?>> That makes Broadcom's FullMAC firmware believe that a given station >> just connected to another AP in a network (which doesn't even exist). >> As a result firmware immediately disassociates that station. It's >> simply impossible to connect to the router. Every association is >> followed by immediate disassociation. >> >> >> Can you see any solution for this problem? Is that an option to stop >> multicast-to-unicast from touching 802.11f packets? Some other ideas? >> Obviously I can't modify Broadcom's firmware and drop that obsoleted >> standard.As far as I can tell you are correct that the 802.11f amendment was never adopted into the 802.11 standard. I will ask internally if we still have a reason for carrying it in our firmware. Regards, Arend