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ipvs: Decrement ttl
We decrement the IP ttl in all the modes in order to prevent infinite route loops. The changes were done based on Julian Anastasov's suggestions in a prior thread. The ttl based check/discard and the actual decrement are done in __ip_vs_get_out_rt() and in __ip_vs_get_out_rt_v6(), for the IPv6 case. decrement_ttl() implements the actual functionality for the two cases. Signed-off-by: Dwip Banerjee <dwip@linux.vnet.ibm.com> Acked-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: Simon Horman <horms@verge.net.au>
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1 changed files with 54 additions and 0 deletions
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@ -254,6 +254,54 @@ static inline bool ensure_mtu_is_adequate(struct netns_ipvs *ipvs, int skb_af,
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return true;
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}
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static inline bool decrement_ttl(struct netns_ipvs *ipvs,
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int skb_af,
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struct sk_buff *skb)
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{
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struct net *net = ipvs->net;
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#ifdef CONFIG_IP_VS_IPV6
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if (skb_af == AF_INET6) {
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struct dst_entry *dst = skb_dst(skb);
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/* check and decrement ttl */
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if (ipv6_hdr(skb)->hop_limit <= 1) {
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/* Force OUTPUT device used as source address */
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skb->dev = dst->dev;
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icmpv6_send(skb, ICMPV6_TIME_EXCEED,
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ICMPV6_EXC_HOPLIMIT, 0);
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__IP6_INC_STATS(net, ip6_dst_idev(dst),
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IPSTATS_MIB_INHDRERRORS);
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return false;
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}
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/* don't propagate ttl change to cloned packets */
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if (!skb_make_writable(skb, sizeof(struct ipv6hdr)))
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return false;
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ipv6_hdr(skb)->hop_limit--;
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} else
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#endif
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{
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if (ip_hdr(skb)->ttl <= 1) {
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/* Tell the sender its packet died... */
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__IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS);
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icmp_send(skb, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL, 0);
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return false;
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}
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/* don't propagate ttl change to cloned packets */
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if (!skb_make_writable(skb, sizeof(struct iphdr)))
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return false;
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/* Decrease ttl */
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ip_decrease_ttl(ip_hdr(skb));
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}
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return true;
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}
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/* Get route to destination or remote server */
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static int
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__ip_vs_get_out_rt(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
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@ -326,6 +374,9 @@ __ip_vs_get_out_rt(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
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return local;
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}
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if (!decrement_ttl(ipvs, skb_af, skb))
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goto err_put;
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if (likely(!(rt_mode & IP_VS_RT_MODE_TUNNEL))) {
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mtu = dst_mtu(&rt->dst);
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} else {
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@ -473,6 +524,9 @@ __ip_vs_get_out_rt_v6(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
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return local;
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}
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if (!decrement_ttl(ipvs, skb_af, skb))
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goto err_put;
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/* MTU checking */
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if (likely(!(rt_mode & IP_VS_RT_MODE_TUNNEL)))
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mtu = dst_mtu(&rt->dst);
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