Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.6 09/56] bridge: Fix incorrect re-injection of LLDP packets | Date | Sun, 14 Aug 2016 22:37:13 +0200 |
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4.6-stable review patch. If anyone has any objections, please let me know.
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From: Ido Schimmel <idosch@mellanox.com>
[ Upstream commit baedbe55884c003819f5c8c063ec3d2569414296 ]
Commit 8626c56c8279 ("bridge: fix potential use-after-free when hook returns QUEUE or STOLEN verdict") caused LLDP packets arriving through a bridge port to be re-injected to the Rx path with skb->dev set to the bridge device, but this breaks the lldpad daemon.
The lldpad daemon opens a packet socket with protocol set to ETH_P_LLDP for any valid device on the system, which doesn't not include soft devices such as bridge and VLAN.
Since packet sockets (ptype_base) are processed in the Rx path after the Rx handler, LLDP packets with skb->dev set to the bridge device never reach the lldpad daemon.
Fix this by making the bridge's Rx handler re-inject LLDP packets with RX_HANDLER_PASS, which effectively restores the behaviour prior to the mentioned commit.
This means netfilter will never receive LLDP packets coming through a bridge port, as I don't see a way in which we can have okfn() consume the packet without breaking existing behaviour. I've already carried out a similar fix for STP packets in commit 56fae404fb2c ("bridge: Fix incorrect re-injection of STP packets").
Fixes: 8626c56c8279 ("bridge: fix potential use-after-free when hook returns QUEUE or STOLEN verdict") Signed-off-by: Ido Schimmel <idosch@mellanox.com> Reviewed-by: Jiri Pirko <jiri@mellanox.com> Cc: Florian Westphal <fw@strlen.de> Cc: John Fastabend <john.fastabend@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/bridge/br_input.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)
--- a/net/bridge/br_input.c +++ b/net/bridge/br_input.c @@ -213,6 +213,16 @@ drop: } EXPORT_SYMBOL_GPL(br_handle_frame_finish); +static void __br_handle_local_finish(struct sk_buff *skb) +{ + struct net_bridge_port *p = br_port_get_rcu(skb->dev); + u16 vid = 0; + + /* check if vlan is allowed, to avoid spoofing */ + if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid)) + br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false); +} + /* note: already called with rcu_read_lock */ static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb) { @@ -279,6 +289,14 @@ rx_handler_result_t br_handle_frame(stru case 0x01: /* IEEE MAC (Pause) */ goto drop; + case 0x0E: /* 802.1AB LLDP */ + fwd_mask |= p->br->group_fwd_mask; + if (fwd_mask & (1u << dest[5])) + goto forward; + *pskb = skb; + __br_handle_local_finish(skb); + return RX_HANDLER_PASS; + default: /* Allow selective forwarding for most other protocols */ fwd_mask |= p->br->group_fwd_mask;
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