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authorJohannes Berg <johannes@sipsolutions.net>2009-11-19 00:56:30 +0100
committerJohn W. Linville <linville@tuxdriver.com>2009-11-19 11:08:54 -0500
commitad4bb6f8883a13bb0f65b194dae36c62a02ac779 (patch)
treeb395936203ac891b9a537c26b4602f727c4387d0 /include/linux/if.h
parent9bc383de37090ba7ca3ff32a12c9d809dc5867f0 (diff)
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cfg80211: disallow bridging managed/adhoc interfaces
A number of people have tried to add a wireless interface (in managed mode) to a bridge and then complained that it doesn't work. It cannot work, however, because in 802.11 networks all packets need to be acknowledged and as such need to be sent to the right address. Promiscuous doesn't help here. The wireless address format used for these links has only space for three addresses, the * transmitter, which must be equal to the sender (origin) * receiver (on the wireless medium), which is the AP in the case of managed mode * the recipient (destination), which is on the APs local network segment In an IBSS, it is similar, but the receiver and recipient must match and the third address is used as the BSSID. To avoid such mistakes in the future, disallow adding a wireless interface to a bridge. Felix has recently added a four-address mode to the AP and client side that can be used (after negotiating that it is possible, which must happen out-of-band by setting up both sides) for bridging, so allow that case. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Acked-by: Stephen Hemminger <shemminger@vyatta.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'include/linux/if.h')
-rw-r--r--include/linux/if.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/if.h b/include/linux/if.h
index 3b2a46bf8f8..3a9f410a296 100644
--- a/include/linux/if.h
+++ b/include/linux/if.h
@@ -70,6 +70,7 @@
#define IFF_XMIT_DST_RELEASE 0x400 /* dev_hard_start_xmit() is allowed to
* release skb->dst
*/
+#define IFF_DONT_BRIDGE 0x800 /* disallow bridging this ether dev */
#define IF_GET_IFACE 0x0001 /* for querying only */
#define IF_GET_PROTO 0x0002