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kernel: add netfilter-actual-sk patch
Backport of linux kernel commit 46d6c5a to 4.14 kernel. netfilter: use actual socket sk rather than skb sk when routing harder Signed-off-by: Aaron Goodman <aaronjg@stanford.edu>
This commit is contained in:
Aaron Goodman
Petr Štetiar
parent
a448ad7490
commit
c9c7b4b394
234
target/linux/generic/backport-4.14/373-netfilter_actual_sk.patch
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234
target/linux/generic/backport-4.14/373-netfilter_actual_sk.patch
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@ -0,0 +1,234 @@
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From: "Jason A. Donenfeld" <Jason@zx2c4.com>
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To: Pablo Neira Ayuso <pablo@netfilter.org>,
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netfilter-devel@vger.kernel.org, netdev@vger.kernel.org
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Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
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Subject: [PATCH nf 2/2] netfilter: use actual socket sk rather than skb sk when routing harder
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Date: Thu, 29 Oct 2020 03:56:06 +0100
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Message-ID: <20201029025606.3523771-3-Jason@zx2c4.com> (raw)
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In-Reply-To: <20201029025606.3523771-1-Jason@zx2c4.com>
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If netfilter changes the packet mark when mangling, the packet is
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rerouted using the route_me_harder set of functions. Prior to this
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commit, there's one big difference between route_me_harder and the
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ordinary initial routing functions, described in the comment above
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__ip_queue_xmit():
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/* Note: skb->sk can be different from sk, in case of tunnels */
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int __ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
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That function goes on to correctly make use of sk->sk_bound_dev_if,
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rather than skb->sk->sk_bound_dev_if. And indeed the comment is true: a
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tunnel will receive a packet in ndo_start_xmit with an initial skb->sk.
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It will make some transformations to that packet, and then it will send
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the encapsulated packet out of a *new* socket. That new socket will
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basically always have a different sk_bound_dev_if (otherwise there'd be
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a routing loop). So for the purposes of routing the encapsulated packet,
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the routing information as it pertains to the socket should come from
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that socket's sk, rather than the packet's original skb->sk. For that
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reason __ip_queue_xmit() and related functions all do the right thing.
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One might argue that all tunnels should just call skb_orphan(skb) before
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transmitting the encapsulated packet into the new socket. But tunnels do
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*not* do this -- and this is wisely avoided in skb_scrub_packet() too --
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because features like TSQ rely on skb->destructor() being called when
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that buffer space is truely available again. Calling skb_orphan(skb) too
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early would result in buffers filling up unnecessarily and accounting
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info being all wrong. Instead, additional routing must take into account
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the new sk, just as __ip_queue_xmit() notes.
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So, this commit addresses the problem by fishing the correct sk out of
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state->sk -- it's already set properly in the call to nf_hook() in
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__ip_local_out(), which receives the sk as part of its normal
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functionality. So we make sure to plumb state->sk through the various
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route_me_harder functions, and then make correct use of it following the
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example of __ip_queue_xmit().
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Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
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Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
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[aaronjg@stanford.edu: backported to 4.14]
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Signed-off-by: Aaron Goodman <aaronjg@stanford.edu>
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--- a/include/linux/netfilter_ipv4.h
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+++ b/include/linux/netfilter_ipv4.h
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@@ -16,7 +16,7 @@ struct ip_rt_info {
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u_int32_t mark;
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};
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-int ip_route_me_harder(struct net *net, struct sk_buff *skb, unsigned addr_type);
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+int ip_route_me_harder(struct net *net, struct sock *sk, struct sk_buff *skb, unsigned addr_type);
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struct nf_queue_entry;
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--- a/include/linux/netfilter_ipv6.h
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+++ b/include/linux/netfilter_ipv6.h
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@@ -41,7 +41,7 @@ struct nf_ipv6_ops {
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};
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#ifdef CONFIG_NETFILTER
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-int ip6_route_me_harder(struct net *net, struct sk_buff *skb);
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+int ip6_route_me_harder(struct net *net, struct sock *sk, struct sk_buff *skb);
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__sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
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unsigned int dataoff, u_int8_t protocol);
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--- a/net/ipv4/netfilter.c
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+++ b/net/ipv4/netfilter.c
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@@ -17,17 +17,19 @@
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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 sk_buff *skb, unsigned int addr_type)
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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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- const struct sock *sk = skb_to_full_sk(skb);
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- __u8 flags = sk ? inet_sk_flowi_flags(sk) : 0;
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+ __u8 flags;
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struct net_device *dev = skb_dst(skb)->dev;
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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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+
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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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@@ -91,7 +93,7 @@ int nf_ip_reroute(struct sk_buff *skb, c
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skb->mark == rt_info->mark &&
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iph->daddr == rt_info->daddr &&
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iph->saddr == rt_info->saddr))
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- return ip_route_me_harder(entry->state.net, skb,
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+ return ip_route_me_harder(entry->state.net, entry->state.sk, skb,
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RTN_UNSPEC);
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}
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return 0;
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--- a/net/ipv4/netfilter/ipt_SYNPROXY.c
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+++ b/net/ipv4/netfilter/ipt_SYNPROXY.c
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@@ -53,7 +53,7 @@ synproxy_send_tcp(struct net *net,
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skb_dst_set_noref(nskb, skb_dst(skb));
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nskb->protocol = htons(ETH_P_IP);
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- if (ip_route_me_harder(net, nskb, RTN_UNSPEC))
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+ if (ip_route_me_harder(net, nskb->sk, nskb, RTN_UNSPEC))
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goto free_nskb;
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if (nfct) {
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--- a/net/ipv4/netfilter/iptable_mangle.c
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+++ b/net/ipv4/netfilter/iptable_mangle.c
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@@ -65,7 +65,7 @@ ipt_mangle_out(struct sk_buff *skb, cons
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iph->daddr != daddr ||
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skb->mark != mark ||
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iph->tos != tos) {
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- err = ip_route_me_harder(state->net, skb, RTN_UNSPEC);
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+ err = ip_route_me_harder(state->net, state->sk, skb, RTN_UNSPEC);
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if (err < 0)
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ret = NF_DROP_ERR(err);
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}
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--- a/net/ipv4/netfilter/nf_nat_l3proto_ipv4.c
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+++ b/net/ipv4/netfilter/nf_nat_l3proto_ipv4.c
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@@ -397,7 +397,7 @@ nf_nat_ipv4_local_fn(void *priv, struct
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if (ct->tuplehash[dir].tuple.dst.u3.ip !=
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ct->tuplehash[!dir].tuple.src.u3.ip) {
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- err = ip_route_me_harder(state->net, skb, RTN_UNSPEC);
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+ err = ip_route_me_harder(state->net, state->sk, skb, RTN_UNSPEC);
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if (err < 0)
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ret = NF_DROP_ERR(err);
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}
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--- a/net/ipv4/netfilter/nf_reject_ipv4.c
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+++ b/net/ipv4/netfilter/nf_reject_ipv4.c
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@@ -129,7 +129,7 @@ void nf_send_reset(struct net *net, stru
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ip4_dst_hoplimit(skb_dst(nskb)));
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nf_reject_ip_tcphdr_put(nskb, oldskb, oth);
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- if (ip_route_me_harder(net, nskb, RTN_UNSPEC))
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+ if (ip_route_me_harder(net, nskb->sk, nskb, RTN_UNSPEC))
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goto free_nskb;
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niph = ip_hdr(nskb);
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--- a/net/ipv4/netfilter/nft_chain_route_ipv4.c
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+++ b/net/ipv4/netfilter/nft_chain_route_ipv4.c
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@@ -50,7 +50,7 @@ static unsigned int nf_route_table_hook(
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iph->daddr != daddr ||
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skb->mark != mark ||
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iph->tos != tos) {
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- err = ip_route_me_harder(state->net, skb, RTN_UNSPEC);
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+ err = ip_route_me_harder(state->net, state->sk, skb, RTN_UNSPEC);
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if (err < 0)
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ret = NF_DROP_ERR(err);
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}
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--- a/net/ipv6/netfilter.c
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+++ b/net/ipv6/netfilter.c
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@@ -18,10 +18,10 @@
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#include <net/ip6_checksum.h>
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#include <net/netfilter/nf_queue.h>
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-int ip6_route_me_harder(struct net *net, struct sk_buff *skb)
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+int ip6_route_me_harder(struct net *net, struct sock *sk_partial, struct sk_buff *skb)
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{
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const struct ipv6hdr *iph = ipv6_hdr(skb);
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- struct sock *sk = sk_to_full_sk(skb->sk);
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+ struct sock *sk = sk_to_full_sk(sk_partial);
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unsigned int hh_len;
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struct dst_entry *dst;
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int strict = (ipv6_addr_type(&iph->daddr) &
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@@ -82,7 +82,7 @@ static int nf_ip6_reroute(struct sk_buff
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if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
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!ipv6_addr_equal(&iph->saddr, &rt_info->saddr) ||
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skb->mark != rt_info->mark)
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- return ip6_route_me_harder(entry->state.net, skb);
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+ return ip6_route_me_harder(entry->state.net, entry->state.sk, skb);
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}
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return 0;
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}
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--- a/net/ipv6/netfilter/ip6table_mangle.c
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+++ b/net/ipv6/netfilter/ip6table_mangle.c
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@@ -60,7 +60,7 @@ ip6t_mangle_out(struct sk_buff *skb, con
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skb->mark != mark ||
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ipv6_hdr(skb)->hop_limit != hop_limit ||
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flowlabel != *((u_int32_t *)ipv6_hdr(skb)))) {
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- err = ip6_route_me_harder(state->net, skb);
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+ err = ip6_route_me_harder(state->net, state->sk, skb);
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if (err < 0)
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ret = NF_DROP_ERR(err);
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}
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--- a/net/ipv6/netfilter/nf_nat_l3proto_ipv6.c
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+++ b/net/ipv6/netfilter/nf_nat_l3proto_ipv6.c
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@@ -414,7 +414,7 @@ nf_nat_ipv6_local_fn(void *priv, struct
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if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3,
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&ct->tuplehash[!dir].tuple.src.u3)) {
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- err = ip6_route_me_harder(state->net, skb);
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+ err = ip6_route_me_harder(state->net, state->sk, skb);
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if (err < 0)
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ret = NF_DROP_ERR(err);
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}
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--- a/net/ipv6/netfilter/nft_chain_route_ipv6.c
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+++ b/net/ipv6/netfilter/nft_chain_route_ipv6.c
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@@ -52,7 +52,7 @@ static unsigned int nf_route_table_hook(
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skb->mark != mark ||
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ipv6_hdr(skb)->hop_limit != hop_limit ||
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flowlabel != *((u_int32_t *)ipv6_hdr(skb)))) {
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- err = ip6_route_me_harder(state->net, skb);
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+ err = ip6_route_me_harder(state->net, state->sk, skb);
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if (err < 0)
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ret = NF_DROP_ERR(err);
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}
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--- a/net/netfilter/ipvs/ip_vs_core.c
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+++ b/net/netfilter/ipvs/ip_vs_core.c
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@@ -713,12 +713,12 @@ static int ip_vs_route_me_harder(struct
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struct dst_entry *dst = skb_dst(skb);
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if (dst->dev && !(dst->dev->flags & IFF_LOOPBACK) &&
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- ip6_route_me_harder(ipvs->net, skb) != 0)
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+ ip6_route_me_harder(ipvs->net, skb->sk, skb) != 0)
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return 1;
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} else
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#endif
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if (!(skb_rtable(skb)->rt_flags & RTCF_LOCAL) &&
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- ip_route_me_harder(ipvs->net, skb, RTN_LOCAL) != 0)
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+ ip_route_me_harder(ipvs->net, skb->sk, skb, RTN_LOCAL) != 0)
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return 1;
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return 0;
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