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354 lines
9.5 KiB
354 lines
9.5 KiB
From: Pablo Neira Ayuso <pablo@netfilter.org>
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Date: Sun, 7 Jan 2018 01:04:19 +0100
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Subject: [PATCH] netfilter: flow table support for IPv6
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This patch adds the IPv6 flow table type, that implements the datapath
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flow table to forward IPv6 traffic.
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This patch exports ip6_dst_mtu_forward() that is required to check for
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mtu to pass up packets that need PMTUD handling to the classic
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forwarding path.
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Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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---
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create mode 100644 net/ipv6/netfilter/nf_flow_table_ipv6.c
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--- a/include/net/ipv6.h
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+++ b/include/net/ipv6.h
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@@ -911,6 +911,8 @@ static inline struct sk_buff *ip6_finish
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&inet6_sk(sk)->cork);
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}
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+unsigned int ip6_dst_mtu_forward(const struct dst_entry *dst);
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+
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int ip6_dst_lookup(struct net *net, struct sock *sk, struct dst_entry **dst,
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struct flowi6 *fl6);
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struct dst_entry *ip6_dst_lookup_flow(const struct sock *sk, struct flowi6 *fl6,
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--- a/net/ipv6/ip6_output.c
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+++ b/net/ipv6/ip6_output.c
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@@ -383,7 +383,7 @@ static inline int ip6_forward_finish(str
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return dst_output(net, sk, skb);
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}
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-static unsigned int ip6_dst_mtu_forward(const struct dst_entry *dst)
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+unsigned int ip6_dst_mtu_forward(const struct dst_entry *dst)
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{
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unsigned int mtu;
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struct inet6_dev *idev;
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@@ -403,6 +403,7 @@ static unsigned int ip6_dst_mtu_forward(
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return mtu;
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}
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+EXPORT_SYMBOL_GPL(ip6_dst_mtu_forward);
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static bool ip6_pkt_too_big(const struct sk_buff *skb, unsigned int mtu)
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{
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--- a/net/ipv6/netfilter/Kconfig
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+++ b/net/ipv6/netfilter/Kconfig
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@@ -99,6 +99,14 @@ config NFT_FIB_IPV6
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endif # NF_TABLES_IPV6
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endif # NF_TABLES
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+config NF_FLOW_TABLE_IPV6
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+ select NF_FLOW_TABLE
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+ tristate "Netfilter flow table IPv6 module"
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+ help
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+ This option adds the flow table IPv6 support.
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+
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+ To compile it as a module, choose M here.
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+
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config NF_DUP_IPV6
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tristate "Netfilter IPv6 packet duplication to alternate destination"
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depends on !NF_CONNTRACK || NF_CONNTRACK
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--- a/net/ipv6/netfilter/Makefile
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+++ b/net/ipv6/netfilter/Makefile
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@@ -45,6 +45,9 @@ obj-$(CONFIG_NFT_REDIR_IPV6) += nft_redi
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obj-$(CONFIG_NFT_DUP_IPV6) += nft_dup_ipv6.o
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obj-$(CONFIG_NFT_FIB_IPV6) += nft_fib_ipv6.o
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+# flow table support
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+obj-$(CONFIG_NF_FLOW_TABLE_IPV6) += nf_flow_table_ipv6.o
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+
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# matches
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obj-$(CONFIG_IP6_NF_MATCH_AH) += ip6t_ah.o
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obj-$(CONFIG_IP6_NF_MATCH_EUI64) += ip6t_eui64.o
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--- /dev/null
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+++ b/net/ipv6/netfilter/nf_flow_table_ipv6.c
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@@ -0,0 +1,277 @@
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+#include <linux/kernel.h>
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+#include <linux/init.h>
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+#include <linux/module.h>
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+#include <linux/netfilter.h>
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+#include <linux/rhashtable.h>
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+#include <linux/ipv6.h>
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+#include <linux/netdevice.h>
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+#include <linux/ipv6.h>
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+#include <net/ipv6.h>
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+#include <net/ip6_route.h>
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+#include <net/neighbour.h>
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+#include <net/netfilter/nf_flow_table.h>
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+#include <net/netfilter/nf_tables.h>
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+/* For layer 4 checksum field offset. */
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+#include <linux/tcp.h>
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+#include <linux/udp.h>
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+
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+static int nf_flow_nat_ipv6_tcp(struct sk_buff *skb, unsigned int thoff,
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+ struct in6_addr *addr,
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+ struct in6_addr *new_addr)
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+{
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+ struct tcphdr *tcph;
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+
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+ if (!pskb_may_pull(skb, thoff + sizeof(*tcph)) ||
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+ skb_try_make_writable(skb, thoff + sizeof(*tcph)))
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+ return -1;
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+
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+ tcph = (void *)(skb_network_header(skb) + thoff);
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+ inet_proto_csum_replace16(&tcph->check, skb, addr->s6_addr32,
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+ new_addr->s6_addr32, true);
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+
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+ return 0;
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+}
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+
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+static int nf_flow_nat_ipv6_udp(struct sk_buff *skb, unsigned int thoff,
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+ struct in6_addr *addr,
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+ struct in6_addr *new_addr)
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+{
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+ struct udphdr *udph;
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+
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+ if (!pskb_may_pull(skb, thoff + sizeof(*udph)) ||
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+ skb_try_make_writable(skb, thoff + sizeof(*udph)))
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+ return -1;
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+
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+ udph = (void *)(skb_network_header(skb) + thoff);
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+ if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
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+ inet_proto_csum_replace16(&udph->check, skb, addr->s6_addr32,
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+ new_addr->s6_addr32, true);
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+ if (!udph->check)
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+ udph->check = CSUM_MANGLED_0;
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+ }
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+
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+ return 0;
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+}
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+
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+static int nf_flow_nat_ipv6_l4proto(struct sk_buff *skb, struct ipv6hdr *ip6h,
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+ unsigned int thoff, struct in6_addr *addr,
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+ struct in6_addr *new_addr)
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+{
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+ switch (ip6h->nexthdr) {
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+ case IPPROTO_TCP:
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+ if (nf_flow_nat_ipv6_tcp(skb, thoff, addr, new_addr) < 0)
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+ return NF_DROP;
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+ break;
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+ case IPPROTO_UDP:
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+ if (nf_flow_nat_ipv6_udp(skb, thoff, addr, new_addr) < 0)
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+ return NF_DROP;
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+ break;
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+ }
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+
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+ return 0;
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+}
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+
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+static int nf_flow_snat_ipv6(const struct flow_offload *flow,
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+ struct sk_buff *skb, struct ipv6hdr *ip6h,
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+ unsigned int thoff,
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+ enum flow_offload_tuple_dir dir)
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+{
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+ struct in6_addr addr, new_addr;
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+
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+ switch (dir) {
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+ case FLOW_OFFLOAD_DIR_ORIGINAL:
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+ addr = ip6h->saddr;
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+ new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_v6;
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+ ip6h->saddr = new_addr;
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+ break;
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+ case FLOW_OFFLOAD_DIR_REPLY:
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+ addr = ip6h->daddr;
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+ new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_v6;
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+ ip6h->daddr = new_addr;
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+ break;
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+ default:
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+ return -1;
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+ }
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+
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+ return nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
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+}
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+
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+static int nf_flow_dnat_ipv6(const struct flow_offload *flow,
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+ struct sk_buff *skb, struct ipv6hdr *ip6h,
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+ unsigned int thoff,
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+ enum flow_offload_tuple_dir dir)
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+{
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+ struct in6_addr addr, new_addr;
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+
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+ switch (dir) {
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+ case FLOW_OFFLOAD_DIR_ORIGINAL:
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+ addr = ip6h->daddr;
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+ new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_v6;
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+ ip6h->daddr = new_addr;
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+ break;
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+ case FLOW_OFFLOAD_DIR_REPLY:
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+ addr = ip6h->saddr;
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+ new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_v6;
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+ ip6h->saddr = new_addr;
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+ break;
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+ default:
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+ return -1;
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+ }
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+
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+ return nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
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+}
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+
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+static int nf_flow_nat_ipv6(const struct flow_offload *flow,
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+ struct sk_buff *skb,
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+ enum flow_offload_tuple_dir dir)
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+{
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+ struct ipv6hdr *ip6h = ipv6_hdr(skb);
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+ unsigned int thoff = sizeof(*ip6h);
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+
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+ if (flow->flags & FLOW_OFFLOAD_SNAT &&
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+ (nf_flow_snat_port(flow, skb, thoff, ip6h->nexthdr, dir) < 0 ||
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+ nf_flow_snat_ipv6(flow, skb, ip6h, thoff, dir) < 0))
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+ return -1;
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+ if (flow->flags & FLOW_OFFLOAD_DNAT &&
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+ (nf_flow_dnat_port(flow, skb, thoff, ip6h->nexthdr, dir) < 0 ||
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+ nf_flow_dnat_ipv6(flow, skb, ip6h, thoff, dir) < 0))
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+ return -1;
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+
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+ return 0;
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+}
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+
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+static int nf_flow_tuple_ipv6(struct sk_buff *skb, const struct net_device *dev,
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+ struct flow_offload_tuple *tuple)
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+{
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+ struct flow_ports *ports;
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+ struct ipv6hdr *ip6h;
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+ unsigned int thoff;
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+
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+ if (!pskb_may_pull(skb, sizeof(*ip6h)))
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+ return -1;
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+
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+ ip6h = ipv6_hdr(skb);
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+
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+ if (ip6h->nexthdr != IPPROTO_TCP &&
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+ ip6h->nexthdr != IPPROTO_UDP)
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+ return -1;
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+
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+ thoff = sizeof(*ip6h);
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+ if (!pskb_may_pull(skb, thoff + sizeof(*ports)))
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+ return -1;
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+
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+ ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
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+
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+ tuple->src_v6 = ip6h->saddr;
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+ tuple->dst_v6 = ip6h->daddr;
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+ tuple->src_port = ports->source;
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+ tuple->dst_port = ports->dest;
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+ tuple->l3proto = AF_INET6;
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+ tuple->l4proto = ip6h->nexthdr;
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+ tuple->iifidx = dev->ifindex;
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+
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+ return 0;
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+}
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+
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+/* Based on ip_exceeds_mtu(). */
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+static bool __nf_flow_exceeds_mtu(const struct sk_buff *skb, unsigned int mtu)
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+{
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+ if (skb->len <= mtu)
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+ return false;
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+
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+ if (skb_is_gso(skb) && skb_gso_validate_mtu(skb, mtu))
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+ return false;
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+
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+ return true;
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+}
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+
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+static bool nf_flow_exceeds_mtu(struct sk_buff *skb, const struct rt6_info *rt)
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+{
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+ u32 mtu;
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+
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+ mtu = ip6_dst_mtu_forward(&rt->dst);
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+ if (__nf_flow_exceeds_mtu(skb, mtu))
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+ return true;
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+
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+ return false;
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+}
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+
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+static unsigned int
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+nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
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+ const struct nf_hook_state *state)
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+{
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+ struct flow_offload_tuple_rhash *tuplehash;
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+ struct nf_flowtable *flow_table = priv;
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+ struct flow_offload_tuple tuple = {};
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+ enum flow_offload_tuple_dir dir;
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+ struct flow_offload *flow;
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+ struct net_device *outdev;
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+ struct in6_addr *nexthop;
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+ struct ipv6hdr *ip6h;
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+ struct rt6_info *rt;
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+
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+ if (skb->protocol != htons(ETH_P_IPV6))
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+ return NF_ACCEPT;
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+
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+ if (nf_flow_tuple_ipv6(skb, state->in, &tuple) < 0)
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+ return NF_ACCEPT;
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+
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+ tuplehash = flow_offload_lookup(flow_table, &tuple);
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+ if (tuplehash == NULL)
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+ return NF_ACCEPT;
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+
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+ outdev = dev_get_by_index_rcu(state->net, tuplehash->tuple.oifidx);
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+ if (!outdev)
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+ return NF_ACCEPT;
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+
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+ dir = tuplehash->tuple.dir;
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+ flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
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+
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+ rt = (struct rt6_info *)flow->tuplehash[dir].tuple.dst_cache;
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+ if (unlikely(nf_flow_exceeds_mtu(skb, rt)))
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+ return NF_ACCEPT;
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+
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+ if (skb_try_make_writable(skb, sizeof(*ip6h)))
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+ return NF_DROP;
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+
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+ if (flow->flags & (FLOW_OFFLOAD_SNAT | FLOW_OFFLOAD_DNAT) &&
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+ nf_flow_nat_ipv6(flow, skb, dir) < 0)
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+ return NF_DROP;
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+
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+ flow->timeout = (u32)jiffies + NF_FLOW_TIMEOUT;
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+ ip6h = ipv6_hdr(skb);
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+ ip6h->hop_limit--;
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+
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+ skb->dev = outdev;
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+ nexthop = rt6_nexthop(rt, &flow->tuplehash[!dir].tuple.src_v6);
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+ neigh_xmit(NEIGH_ND_TABLE, outdev, nexthop, skb);
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+
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+ return NF_STOLEN;
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+}
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+
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+static struct nf_flowtable_type flowtable_ipv6 = {
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+ .family = NFPROTO_IPV6,
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+ .params = &nf_flow_offload_rhash_params,
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+ .gc = nf_flow_offload_work_gc,
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+ .hook = nf_flow_offload_ipv6_hook,
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+ .owner = THIS_MODULE,
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+};
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+
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+static int __init nf_flow_ipv6_module_init(void)
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+{
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+ nft_register_flowtable_type(&flowtable_ipv6);
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+
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+ return 0;
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+}
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+
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+static void __exit nf_flow_ipv6_module_exit(void)
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+{
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+ nft_unregister_flowtable_type(&flowtable_ipv6);
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+}
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+
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+module_init(nf_flow_ipv6_module_init);
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+module_exit(nf_flow_ipv6_module_exit);
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+
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+MODULE_LICENSE("GPL");
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+MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
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+MODULE_ALIAS_NF_FLOWTABLE(AF_INET6);
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