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| author |   Jesper Dangaard Brouer <brouer@redhat.com> | 2018-10-09 12:04:43 +0200 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2018-10-09 21:59:09 -0700 |
| commit | 2972495699320229b55b8e5065a310be5c81485b (patch) | |
| tree | 817a6d59427a927677f69f6efe97d5f98e6f1267 /net/core/dev.c | |
| parent | Merge branch 'unsupported-map-lookup' (diff) | |
| download | linux-dev-2972495699320229b55b8e5065a310be5c81485b.tar.xz linux-dev-2972495699320229b55b8e5065a310be5c81485b.zip | |
net: fix generic XDP to handle if eth header was mangled
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 <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'net/core/dev.c')
| -rw-r--r-- | net/core/dev.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 0b2d777e5b9e..ec96f50b0782 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4258,6 +4258,9 @@ 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; @@ -4298,6 +4301,9 @@ 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; @@ -4321,6 +4327,14 @@ 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: |