From 3576fd794b38306e196498ac54bb3b21c32e1ae4 Mon Sep 17 00:00:00 2001 From: Glenn Griffin Date: Mon, 3 Aug 2015 09:56:54 -0700 Subject: [PATCH] openvswitch: Fix L4 checksum handling when dealing with IP fragments openvswitch modifies the L4 checksum of a packet when modifying the ip address. When an IP packet is fragmented only the first fragment contains an L4 header and checksum. Prior to this change openvswitch would modify all fragments, modifying application data in non-first fragments, causing checksum failures in the reassembled packet. Signed-off-by: Glenn Griffin Acked-by: Pravin B Shelar Signed-off-by: David S. Miller --- net/openvswitch/actions.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c index 8a8c0b8b4f63..ee34f474ad14 100644 --- a/net/openvswitch/actions.c +++ b/net/openvswitch/actions.c @@ -273,28 +273,36 @@ static int set_eth_addr(struct sk_buff *skb, struct sw_flow_key *flow_key, return 0; } -static void set_ip_addr(struct sk_buff *skb, struct iphdr *nh, - __be32 *addr, __be32 new_addr) +static void update_ip_l4_checksum(struct sk_buff *skb, struct iphdr *nh, + __be32 addr, __be32 new_addr) { int transport_len = skb->len - skb_transport_offset(skb); + if (nh->frag_off & htons(IP_OFFSET)) + return; + if (nh->protocol == IPPROTO_TCP) { if (likely(transport_len >= sizeof(struct tcphdr))) inet_proto_csum_replace4(&tcp_hdr(skb)->check, skb, - *addr, new_addr, 1); + addr, new_addr, 1); } else if (nh->protocol == IPPROTO_UDP) { if (likely(transport_len >= sizeof(struct udphdr))) { struct udphdr *uh = udp_hdr(skb); if (uh->check || skb->ip_summed == CHECKSUM_PARTIAL) { inet_proto_csum_replace4(&uh->check, skb, - *addr, new_addr, 1); + addr, new_addr, 1); if (!uh->check) uh->check = CSUM_MANGLED_0; } } } +} +static void set_ip_addr(struct sk_buff *skb, struct iphdr *nh, + __be32 *addr, __be32 new_addr) +{ + update_ip_l4_checksum(skb, nh, *addr, new_addr); csum_replace4(&nh->check, *addr, new_addr); skb_clear_hash(skb); *addr = new_addr; -- 2.20.1