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[03/11] vti6: fix ipv4 pmtu check to honor ip header df

Message ID 20210331081847.3547641-4-steffen.klassert@secunet.com
State New
Headers show
Series None | expand

Commit Message

Steffen Klassert March 31, 2021, 8:18 a.m. UTC 
From: Eyal Birger <eyal.birger@gmail.com>

Frag needed should only be sent if the header enables DF.

This fix allows IPv4 packets larger than MTU to pass the vti6 interface
and be fragmented after encapsulation, aligning behavior with
non-vti6 xfrm.

Fixes: ccd740cbc6e0 ("vti6: Add pmtu handling to vti6_xmit.")
Signed-off-by: Eyal Birger <eyal.birger@gmail.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
 net/ipv6/ip6_vti.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
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Patch

diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
index 0225fd694192..2f0be5ac021c 100644
--- a/net/ipv6/ip6_vti.c
+++ b/net/ipv6/ip6_vti.c
@@ -494,7 +494,7 @@  vti6_xmit(struct sk_buff *skb, struct net_device *dev, struct flowi *fl)
 	}
 
 	if (dst->flags & DST_XFRM_QUEUE)
-		goto queued;
+		goto xmit;
 
 	x = dst->xfrm;
 	if (!vti6_state_check(x, &t->parms.raddr, &t->parms.laddr))
@@ -523,6 +523,8 @@  vti6_xmit(struct sk_buff *skb, struct net_device *dev, struct flowi *fl)
 
 			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
 		} else {
+			if (!(ip_hdr(skb)->frag_off & htons(IP_DF)))
+				goto xmit;
 			icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
 				  htonl(mtu));
 		}
@@ -531,7 +533,7 @@  vti6_xmit(struct sk_buff *skb, struct net_device *dev, struct flowi *fl)
 		goto tx_err_dst_release;
 	}
 
-queued:
+xmit:
 	skb_scrub_packet(skb, !net_eq(t->net, dev_net(dev)));
 	skb_dst_set(skb, dst);
 	skb->dev = skb_dst(skb)->dev;