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authorFlorian Westphal <fw@strlen.de>2022-06-20 16:17:30 +0200
committerPablo Neira Ayuso <pablo@netfilter.org>2022-06-21 10:50:40 +0200
commit574a5b85dc3b9ab672ff3fba0ee020f927960648 (patch)
tree97357fd42503d008036961aa4a5b11bfed832920 /net
parent5d79d8af8dec58bf709b3124d09d9572edd9c617 (diff)
netfilter: nf_dup_netdev: do not push mac header a second time
Eric reports skb_under_panic when using dup/fwd via bond+egress hook. Before pushing mac header, we should make sure that we're called from ingress to put back what was pulled earlier. In egress case, the MAC header is already there; we should leave skb alone. While at it be more careful here: skb might have been altered and headroom reduced, so add a skb_cow() before so that headroom is increased if necessary. nf_do_netdev_egress() assumes skb ownership (it normally ends with a call to dev_queue_xmit), so we must free the packet on error. Fixes: f87b9464d152 ("netfilter: nft_fwd_netdev: Support egress hook") Reported-by: Eric Garver <eric@garver.life> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/nf_dup_netdev.c14
1 files changed, 10 insertions, 4 deletions
diff --git a/net/netfilter/nf_dup_netdev.c b/net/netfilter/nf_dup_netdev.c
index 7873bd1389c3..13b7f6a66086 100644
--- a/net/netfilter/nf_dup_netdev.c
+++ b/net/netfilter/nf_dup_netdev.c
@@ -13,10 +13,16 @@
#include <net/netfilter/nf_tables_offload.h>
#include <net/netfilter/nf_dup_netdev.h>
-static void nf_do_netdev_egress(struct sk_buff *skb, struct net_device *dev)
+static void nf_do_netdev_egress(struct sk_buff *skb, struct net_device *dev,
+ enum nf_dev_hooks hook)
{
- if (skb_mac_header_was_set(skb))
+ if (hook == NF_NETDEV_INGRESS && skb_mac_header_was_set(skb)) {
+ if (skb_cow_head(skb, skb->mac_len)) {
+ kfree_skb(skb);
+ return;
+ }
skb_push(skb, skb->mac_len);
+ }
skb->dev = dev;
skb_clear_tstamp(skb);
@@ -33,7 +39,7 @@ void nf_fwd_netdev_egress(const struct nft_pktinfo *pkt, int oif)
return;
}
- nf_do_netdev_egress(pkt->skb, dev);
+ nf_do_netdev_egress(pkt->skb, dev, nft_hook(pkt));
}
EXPORT_SYMBOL_GPL(nf_fwd_netdev_egress);
@@ -48,7 +54,7 @@ void nf_dup_netdev_egress(const struct nft_pktinfo *pkt, int oif)
skb = skb_clone(pkt->skb, GFP_ATOMIC);
if (skb)
- nf_do_netdev_egress(skb, dev);
+ nf_do_netdev_egress(skb, dev, nft_hook(pkt));
}
EXPORT_SYMBOL_GPL(nf_dup_netdev_egress);