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authorHerbert Xu <herbert@gondor.apana.org.au>2005-06-20 13:21:43 -0700
committerDavid S. Miller <davem@davemloft.net>2005-06-20 13:21:43 -0700
commitdd87147eed934eaff92869f3d158697c7239d1d2 (patch)
tree5a5d59c2678767530c2a3299a70ccfc14062b347 /net/ipv4/xfrm4_output.c
parentd094cd83c06e06e01d8edb540555f3f64e4081c2 (diff)
[IPSEC]: Add XFRM_STATE_NOPMTUDISC flag
This patch adds the flag XFRM_STATE_NOPMTUDISC for xfrm states. It is similar to the nopmtudisc on IPIP/GRE tunnels. It only has an effect on IPv4 tunnel mode states. For these states, it will ensure that the DF flag is always cleared. This is primarily useful to work around ICMP blackholes. In future this flag could also allow a larger MTU to be set within the tunnel just like IPIP/GRE tunnels. This could be useful for short haul tunnels where temporary fragmentation outside the tunnel is desired over smaller fragments inside the tunnel. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: James Morris <jmorris@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/xfrm4_output.c')
-rw-r--r--net/ipv4/xfrm4_output.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/net/ipv4/xfrm4_output.c b/net/ipv4/xfrm4_output.c
index af2392ae5769..66620a95942a 100644
--- a/net/ipv4/xfrm4_output.c
+++ b/net/ipv4/xfrm4_output.c
@@ -33,6 +33,7 @@ static void xfrm4_encap(struct sk_buff *skb)
struct dst_entry *dst = skb->dst;
struct xfrm_state *x = dst->xfrm;
struct iphdr *iph, *top_iph;
+ int flags;
iph = skb->nh.iph;
skb->h.ipiph = iph;
@@ -51,10 +52,13 @@ static void xfrm4_encap(struct sk_buff *skb)
/* DS disclosed */
top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos);
- if (x->props.flags & XFRM_STATE_NOECN)
+
+ flags = x->props.flags;
+ if (flags & XFRM_STATE_NOECN)
IP_ECN_clear(top_iph);
- top_iph->frag_off = iph->frag_off & htons(IP_DF);
+ top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
+ 0 : (iph->frag_off & htons(IP_DF));
if (!top_iph->frag_off)
__ip_select_ident(top_iph, dst, 0);