From 040468a0a7b3f9c7966126d98151bc64f1423657 Mon Sep 17 00:00:00 2001 From: David Ward Date: Sun, 27 Jan 2013 13:04:58 +0000 Subject: [PATCH] ip_gre: When TOS is inherited, use configured TOS value for non-IP packets A GRE tunnel can be configured so that outgoing tunnel packets inherit the value of the TOS field from the inner IP header. In doing so, when a non-IP packet is transmitted through the tunnel, the TOS field will always be set to 0. Instead, the user should be able to configure a different TOS value as the fallback to use for non-IP packets. This is helpful when the non-IP packets are all control packets and should be handled by routers outside the tunnel as having Internet Control precedence. One example of this is the NHRP packets that control a DMVPN-compatible mGRE tunnel; they are encapsulated directly by GRE and do not contain an inner IP header. Under the existing behavior, the IFLA_GRE_TOS parameter must be set to '1' for the TOS value to be inherited. Now, only the least significant bit of this parameter must be set to '1', and when a non-IP packet is sent through the tunnel, the upper 6 bits of this same parameter will be copied into the TOS field. (The ECN bits get masked off as before.) This behavior is backwards-compatible with existing configurations and iproute2 versions. Signed-off-by: David Ward Signed-off-by: David S. Miller --- net/ipv4/ip_gre.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index af6be70821c4..801e02355ec4 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -820,8 +820,8 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev ttl = tiph->ttl; tos = tiph->tos; - if (tos == 1) { - tos = 0; + if (tos & 0x1) { + tos &= ~0x1; if (skb->protocol == htons(ETH_P_IP)) tos = old_iph->tos; else if (skb->protocol == htons(ETH_P_IPV6)) -- 2.20.1