812fa71f0d
Netfilter tries to reroute mangled packets as a different route might need to be used following the mangling. When this happens, netfilter does not populate the IP protocol, the source port and the destination port in the flow key. Therefore, FIB rules that match on these fields are ignored and packets can be misrouted. Solve this by dissecting the outer flow and populating the flow key before rerouting the packet. Note that flow dissection only happens when FIB rules that match on these fields are installed, so in the common case there should not be a penalty. Reported-by: Michal Soltys <msoltyspl@yandex.pl> Signed-off-by: Ido Schimmel <idosch@nvidia.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
97 lines
2.6 KiB
C
97 lines
2.6 KiB
C
/*
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* IPv4 specific functions of netfilter core
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*
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* Rusty Russell (C) 2000 -- This code is GPL.
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* Patrick McHardy (C) 2006-2012
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*/
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#include <linux/kernel.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/ip.h>
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#include <linux/skbuff.h>
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#include <linux/gfp.h>
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#include <linux/export.h>
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#include <net/route.h>
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#include <net/xfrm.h>
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#include <net/ip.h>
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#include <net/netfilter/nf_queue.h>
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/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
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int ip_route_me_harder(struct net *net, struct sock *sk, struct sk_buff *skb, unsigned int addr_type)
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{
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const struct iphdr *iph = ip_hdr(skb);
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struct rtable *rt;
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struct flowi4 fl4 = {};
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__be32 saddr = iph->saddr;
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__u8 flags;
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struct net_device *dev = skb_dst(skb)->dev;
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struct flow_keys flkeys;
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unsigned int hh_len;
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sk = sk_to_full_sk(sk);
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flags = sk ? inet_sk_flowi_flags(sk) : 0;
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if (addr_type == RTN_UNSPEC)
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addr_type = inet_addr_type_dev_table(net, dev, saddr);
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if (addr_type == RTN_LOCAL || addr_type == RTN_UNICAST)
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flags |= FLOWI_FLAG_ANYSRC;
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else
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saddr = 0;
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/* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
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* packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.
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*/
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fl4.daddr = iph->daddr;
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fl4.saddr = saddr;
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fl4.flowi4_tos = RT_TOS(iph->tos);
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fl4.flowi4_oif = sk ? sk->sk_bound_dev_if : 0;
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if (!fl4.flowi4_oif)
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fl4.flowi4_oif = l3mdev_master_ifindex(dev);
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fl4.flowi4_mark = skb->mark;
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fl4.flowi4_flags = flags;
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fib4_rules_early_flow_dissect(net, skb, &fl4, &flkeys);
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rt = ip_route_output_key(net, &fl4);
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if (IS_ERR(rt))
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return PTR_ERR(rt);
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/* Drop old route. */
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skb_dst_drop(skb);
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skb_dst_set(skb, &rt->dst);
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if (skb_dst(skb)->error)
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return skb_dst(skb)->error;
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#ifdef CONFIG_XFRM
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if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
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xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {
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struct dst_entry *dst = skb_dst(skb);
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skb_dst_set(skb, NULL);
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dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), sk, 0);
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if (IS_ERR(dst))
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return PTR_ERR(dst);
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skb_dst_set(skb, dst);
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}
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#endif
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/* Change in oif may mean change in hh_len. */
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hh_len = skb_dst(skb)->dev->hard_header_len;
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if (skb_headroom(skb) < hh_len &&
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pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
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0, GFP_ATOMIC))
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return -ENOMEM;
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return 0;
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}
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EXPORT_SYMBOL(ip_route_me_harder);
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int nf_ip_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
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bool strict __always_unused)
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{
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struct rtable *rt = ip_route_output_key(net, &fl->u.ip4);
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if (IS_ERR(rt))
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return PTR_ERR(rt);
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*dst = &rt->dst;
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return 0;
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}
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EXPORT_SYMBOL_GPL(nf_ip_route);
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