On Tue, 2015-03-10 at 14:27 +0100, Pablo Neira Ayuso wrote:
> From: Julian Anastasov <ja@xxxxxx>
>
> [ backport from upstream commit 579eb62ac35845686a7c4286c0a820b4eb1f96aa ]
>
> commit f5a41847acc5 ("ipvs: move ip_route_me_harder for ICMP")
> from 2.6.37 introduced ip_route_me_harder() call for responses to
> local clients, so that we can provide valid rt_src after SNAT.
> It was used by TCP to provide valid daddr for ip_send_reply().
> After commit 0a5ebb8000c5 ("ipv4: Pass explicit daddr arg to
> ip_send_reply()." from 3.0 this rerouting is not needed anymore
> and should be avoided, especially in LOCAL_IN.
>
> Fixes 3.12.33 crash in xfrm reported by Florian Wiessner:
> "3.12.33 - BUG xfrm_selector_match+0x25/0x2f6"
>
> Cc: stable@xxxxxxxxxxxxxxx # 3.2.x
> Signed-off-by: Julian Anastasov <ja@xxxxxx>
> Acked-by: Simon Horman <horms@xxxxxxxxxxxx>
Queued up for 3.2, thanks.
Ben.
> ---
>
> net/netfilter/ipvs/ip_vs_core.c | 32 +++++++++++++++++++++-----------
> 1 file changed, 21 insertions(+), 11 deletions(-)
>
> diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
> index 6dc7d7d..d864aaf 100644
> --- a/net/netfilter/ipvs/ip_vs_core.c
> +++ b/net/netfilter/ipvs/ip_vs_core.c
> @@ -662,16 +662,24 @@ static inline int ip_vs_gather_frags_v6(struct sk_buff *skb, u_int32_t user)
> }
> #endif
>
> -static int ip_vs_route_me_harder(int af, struct sk_buff *skb)
> +static int ip_vs_route_me_harder(int af, struct sk_buff *skb,
> + unsigned int hooknum)
> {
> + if (!sysctl_snat_reroute(skb))
> + return 0;
> + /* Reroute replies only to remote clients (FORWARD and LOCAL_OUT) */
> + if (NF_INET_LOCAL_IN == hooknum)
> + return 0;
> #ifdef CONFIG_IP_VS_IPV6
> if (af == AF_INET6) {
> - if (sysctl_snat_reroute(skb) && ip6_route_me_harder(skb) != 0)
> + struct dst_entry *dst = skb_dst(skb);
> +
> + if (dst->dev && !(dst->dev->flags & IFF_LOOPBACK) &&
> + ip6_route_me_harder(skb) != 0)
> return 1;
> } else
> #endif
> - if ((sysctl_snat_reroute(skb) ||
> - skb_rtable(skb)->rt_flags & RTCF_LOCAL) &&
> + if (!(skb_rtable(skb)->rt_flags & RTCF_LOCAL) &&
> ip_route_me_harder(skb, RTN_LOCAL) != 0)
> return 1;
>
> @@ -782,7 +790,8 @@ static int handle_response_icmp(int af, struct sk_buff *skb,
> union nf_inet_addr *snet,
> __u8 protocol, struct ip_vs_conn *cp,
> struct ip_vs_protocol *pp,
> - unsigned int offset, unsigned int ihl)
> + unsigned int offset, unsigned int ihl,
> + unsigned int hooknum)
> {
> unsigned int verdict = NF_DROP;
>
> @@ -812,7 +821,7 @@ static int handle_response_icmp(int af, struct sk_buff *skb,
> #endif
> ip_vs_nat_icmp(skb, pp, cp, 1);
>
> - if (ip_vs_route_me_harder(af, skb))
> + if (ip_vs_route_me_harder(af, skb, hooknum))
> goto out;
>
> /* do the statistics and put it back */
> @@ -908,7 +917,7 @@ static int ip_vs_out_icmp(struct sk_buff *skb, int *related,
>
> snet.ip = iph->saddr;
> return handle_response_icmp(AF_INET, skb, &snet, cih->protocol, cp,
> - pp, offset, ihl);
> + pp, offset, ihl, hooknum);
> }
>
> #ifdef CONFIG_IP_VS_IPV6
> @@ -985,7 +994,8 @@ static int ip_vs_out_icmp_v6(struct sk_buff *skb, int *related,
>
> ipv6_addr_copy(&snet.in6, &iph->saddr);
> return handle_response_icmp(AF_INET6, skb, &snet, cih->nexthdr, cp,
> - pp, offset, sizeof(struct ipv6hdr));
> + pp, offset, sizeof(struct ipv6hdr),
> + hooknum);
> }
> #endif
>
> @@ -1018,7 +1028,7 @@ static inline int is_tcp_reset(const struct sk_buff *skb, int nh_len)
> */
> static unsigned int
> handle_response(int af, struct sk_buff *skb, struct ip_vs_proto_data *pd,
> - struct ip_vs_conn *cp, int ihl)
> + struct ip_vs_conn *cp, int ihl, unsigned int hooknum)
> {
> struct ip_vs_protocol *pp = pd->pp;
>
> @@ -1056,7 +1066,7 @@ handle_response(int af, struct sk_buff *skb, struct ip_vs_proto_data *pd,
> * if it came from this machine itself. So re-compute
> * the routing information.
> */
> - if (ip_vs_route_me_harder(af, skb))
> + if (ip_vs_route_me_harder(af, skb, hooknum))
> goto drop;
>
> IP_VS_DBG_PKT(10, af, pp, skb, 0, "After SNAT");
> @@ -1169,7 +1179,7 @@ ip_vs_out(unsigned int hooknum, struct sk_buff *skb, int af)
> cp = pp->conn_out_get(af, skb, &iph, iph.len, 0);
>
> if (likely(cp))
> - return handle_response(af, skb, pd, cp, iph.len);
> + return handle_response(af, skb, pd, cp, iph.len, hooknum);
> if (sysctl_nat_icmp_send(net) &&
> (pp->protocol == IPPROTO_TCP ||
> pp->protocol == IPPROTO_UDP ||
--
Ben Hutchings
Once a job is fouled up, anything done to improve it makes it worse.
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