| Message ID | 20190429133930.6287-1-shmulik.ladkani@gmail.com |
|---|---|
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net] ipv4: ip_do_fragment: Preserve skb_iif during fragmentation | expand |
From: Shmulik Ladkani <shmulik@metanetworks.com> Date: Mon, 29 Apr 2019 16:39:30 +0300 > Previously, during fragmentation after forwarding, skb->skb_iif isn't > preserved, i.e. 'ip_copy_metadata' does not copy skb_iif from given > 'from' skb. > > As a result, ip_do_fragment's creates fragments with zero skb_iif, > leading to inconsistent behavior. > > Assume for example an eBPF program attached at tc egress (post > forwarding) that examines __sk_buff->ingress_ifindex: > - the correct iif is observed if forwarding path does not involve > fragmentation/refragmentation > - a bogus iif is observed if forwarding path involves > fragmentation/refragmentatiom > > Fix, by preserving skb_iif during 'ip_copy_metadata'. > > Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com> Applied and queued up for -stable.
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 4e42c1974ba2..ac880beda8a7 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -516,6 +516,7 @@ static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) to->pkt_type = from->pkt_type; to->priority = from->priority; to->protocol = from->protocol; + to->skb_iif = from->skb_iif; skb_dst_drop(to); skb_dst_copy(to, from); to->dev = from->dev;
Previously, during fragmentation after forwarding, skb->skb_iif isn't preserved, i.e. 'ip_copy_metadata' does not copy skb_iif from given 'from' skb. As a result, ip_do_fragment's creates fragments with zero skb_iif, leading to inconsistent behavior. Assume for example an eBPF program attached at tc egress (post forwarding) that examines __sk_buff->ingress_ifindex: - the correct iif is observed if forwarding path does not involve fragmentation/refragmentation - a bogus iif is observed if forwarding path involves fragmentation/refragmentatiom Fix, by preserving skb_iif during 'ip_copy_metadata'. Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com> --- net/ipv4/ip_output.c | 1 + 1 file changed, 1 insertion(+)