Commit d2f0c961 authored by Shmulik Ladkani's avatar Shmulik Ladkani Committed by David S. Miller

ipv4: ip_do_fragment: Preserve skb_iif during fragmentation

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: default avatarShmulik Ladkani <shmulik.ladkani@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2dcb0033
...@@ -519,6 +519,7 @@ static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) ...@@ -519,6 +519,7 @@ static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
to->pkt_type = from->pkt_type; to->pkt_type = from->pkt_type;
to->priority = from->priority; to->priority = from->priority;
to->protocol = from->protocol; to->protocol = from->protocol;
to->skb_iif = from->skb_iif;
skb_dst_drop(to); skb_dst_drop(to);
skb_dst_copy(to, from); skb_dst_copy(to, from);
to->dev = from->dev; to->dev = from->dev;
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment