[PATCH AUTOSEL 4.19 178/209] net: fix generic XDP to handle if eth header was mangled
From: Sasha Levin <sashal@kernel.org>
Date: 2019-11-13 02:19:06
Also in:
bpf, lkml, stable
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: Jesper Dangaard Brouer <redacted>
[ Upstream commit 2972495699320229b55b8e5065a310be5c81485b ]
XDP can modify (and resize) the Ethernet header in the packet.
There is a bug in generic-XDP, because skb->protocol and skb->pkt_type
are setup before reaching (netif_receive_)generic_xdp.
This bug was hit when XDP were popping VLAN headers (changing
eth->h_proto), as skb->protocol still contains VLAN-indication
(ETH_P_8021Q) causing invocation of skb_vlan_untag(skb), which corrupt
the packet (basically popping the VLAN again).
This patch catch if XDP changed eth header in such a way, that SKB
fields needs to be updated.
V2: on request from Song Liu, use ETH_HLEN instead of mac_len,
in __skb_push() as eth_type_trans() use ETH_HLEN in paired skb_pull_inline().
Fixes: d445516966dc ("net: xdp: support xdp generic on virtual devices")
Signed-off-by: Jesper Dangaard Brouer <redacted>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/core/dev.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/net/core/dev.c b/net/core/dev.c
index ddd8aab20adf2..3e8b468a9f264 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c@@ -4296,6 +4296,9 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, struct netdev_rx_queue *rxqueue; void *orig_data, *orig_data_end; u32 metalen, act = XDP_DROP; + __be16 orig_eth_type; + struct ethhdr *eth; + bool orig_bcast; int hlen, off; u32 mac_len;
@@ -4336,6 +4339,9 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, xdp->data_hard_start = skb->data - skb_headroom(skb); orig_data_end = xdp->data_end; orig_data = xdp->data; + eth = (struct ethhdr *)xdp->data; + orig_bcast = is_multicast_ether_addr_64bits(eth->h_dest); + orig_eth_type = eth->h_proto; rxqueue = netif_get_rxqueue(skb); xdp->rxq = &rxqueue->xdp_rxq;
@@ -4359,6 +4365,14 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, } + /* check if XDP changed eth hdr such SKB needs update */ + eth = (struct ethhdr *)xdp->data; + if ((orig_eth_type != eth->h_proto) || + (orig_bcast != is_multicast_ether_addr_64bits(eth->h_dest))) { + __skb_push(skb, ETH_HLEN); + skb->protocol = eth_type_trans(skb, skb->dev); + } + switch (act) { case XDP_REDIRECT: case XDP_TX:
--
2.20.1