// SPDX-License-Identifier: GPL-2.0-only
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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/ip.h>
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#include <linux/ipv6.h>
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#include <linux/netdevice.h>
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#include <net/ip.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_conntrack_acct.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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static int nf_flow_state_check(struct flow_offload *flow, int proto,
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struct sk_buff *skb, unsigned int thoff)
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{
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struct tcphdr *tcph;
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if (proto != IPPROTO_TCP)
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return 0;
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tcph = (void *)(skb_network_header(skb) + thoff);
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if (unlikely(tcph->fin || tcph->rst)) {
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flow_offload_teardown(flow);
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return -1;
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}
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return 0;
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}
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static int nf_flow_nat_ip_tcp(struct sk_buff *skb, unsigned int thoff,
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__be32 addr, __be32 new_addr)
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{
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struct tcphdr *tcph;
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if (skb_try_make_writable(skb, thoff + sizeof(*tcph)))
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return -1;
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tcph = (void *)(skb_network_header(skb) + thoff);
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inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, true);
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return 0;
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}
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static int nf_flow_nat_ip_udp(struct sk_buff *skb, unsigned int thoff,
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__be32 addr, __be32 new_addr)
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{
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struct udphdr *udph;
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if (skb_try_make_writable(skb, thoff + sizeof(*udph)))
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return -1;
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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_replace4(&udph->check, skb, addr,
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new_addr, 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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return 0;
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}
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static int nf_flow_nat_ip_l4proto(struct sk_buff *skb, struct iphdr *iph,
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unsigned int thoff, __be32 addr,
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__be32 new_addr)
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{
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switch (iph->protocol) {
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case IPPROTO_TCP:
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if (nf_flow_nat_ip_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_ip_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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return 0;
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}
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static int nf_flow_snat_ip(const struct flow_offload *flow, struct sk_buff *skb,
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struct iphdr *iph, unsigned int thoff,
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enum flow_offload_tuple_dir dir)
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{
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__be32 addr, new_addr;
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switch (dir) {
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case FLOW_OFFLOAD_DIR_ORIGINAL:
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addr = iph->saddr;
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new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_v4.s_addr;
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iph->saddr = new_addr;
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break;
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case FLOW_OFFLOAD_DIR_REPLY:
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addr = iph->daddr;
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new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_v4.s_addr;
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iph->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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csum_replace4(&iph->check, addr, new_addr);
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return nf_flow_nat_ip_l4proto(skb, iph, thoff, addr, new_addr);
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}
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static int nf_flow_dnat_ip(const struct flow_offload *flow, struct sk_buff *skb,
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struct iphdr *iph, unsigned int thoff,
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enum flow_offload_tuple_dir dir)
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{
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__be32 addr, new_addr;
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switch (dir) {
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case FLOW_OFFLOAD_DIR_ORIGINAL:
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addr = iph->daddr;
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new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_v4.s_addr;
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iph->daddr = new_addr;
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break;
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case FLOW_OFFLOAD_DIR_REPLY:
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addr = iph->saddr;
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new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_v4.s_addr;
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iph->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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csum_replace4(&iph->check, addr, new_addr);
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return nf_flow_nat_ip_l4proto(skb, iph, thoff, addr, new_addr);
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}
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static int nf_flow_nat_ip(const struct flow_offload *flow, struct sk_buff *skb,
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unsigned int thoff, enum flow_offload_tuple_dir dir)
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{
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struct iphdr *iph = ip_hdr(skb);
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if (test_bit(NF_FLOW_SNAT, &flow->flags) &&
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(nf_flow_snat_port(flow, skb, thoff, iph->protocol, dir) < 0 ||
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nf_flow_snat_ip(flow, skb, ip_hdr(skb), thoff, dir) < 0))
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return -1;
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iph = ip_hdr(skb);
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if (test_bit(NF_FLOW_DNAT, &flow->flags) &&
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(nf_flow_dnat_port(flow, skb, thoff, iph->protocol, dir) < 0 ||
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nf_flow_dnat_ip(flow, skb, ip_hdr(skb), thoff, dir) < 0))
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return -1;
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return 0;
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}
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static bool ip_has_options(unsigned int thoff)
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{
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return thoff != sizeof(struct iphdr);
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}
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static int nf_flow_tuple_ip(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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unsigned int thoff, hdrsize;
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struct flow_ports *ports;
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struct iphdr *iph;
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if (!pskb_may_pull(skb, sizeof(*iph)))
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return -1;
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iph = ip_hdr(skb);
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thoff = iph->ihl * 4;
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if (ip_is_fragment(iph) ||
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unlikely(ip_has_options(thoff)))
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return -1;
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switch (iph->protocol) {
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case IPPROTO_TCP:
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hdrsize = sizeof(struct tcphdr);
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break;
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case IPPROTO_UDP:
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hdrsize = sizeof(struct udphdr);
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break;
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default:
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return -1;
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}
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if (iph->ttl <= 1)
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return -1;
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thoff = iph->ihl * 4;
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if (!pskb_may_pull(skb, thoff + hdrsize))
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return -1;
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iph = ip_hdr(skb);
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ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
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tuple->src_v4.s_addr = iph->saddr;
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tuple->dst_v4.s_addr = iph->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_INET;
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tuple->l4proto = iph->protocol;
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tuple->iifidx = dev->ifindex;
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return 0;
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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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if (skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu))
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return false;
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return true;
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}
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static int nf_flow_offload_dst_check(struct dst_entry *dst)
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{
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if (unlikely(dst_xfrm(dst)))
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return dst_check(dst, 0) ? 0 : -1;
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return 0;
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}
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static unsigned int nf_flow_xmit_xfrm(struct sk_buff *skb,
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const struct nf_hook_state *state,
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struct dst_entry *dst)
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{
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skb_orphan(skb);
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skb_dst_set_noref(skb, dst);
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dst_output(state->net, state->sk, skb);
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return NF_STOLEN;
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}
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unsigned int
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nf_flow_offload_ip_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 rtable *rt;
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unsigned int thoff;
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struct iphdr *iph;
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__be32 nexthop;
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if (skb->protocol != htons(ETH_P_IP))
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return NF_ACCEPT;
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if (nf_flow_tuple_ip(skb, state->in, &tuple) < 0)
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return NF_ACCEPT;
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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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dir = tuplehash->tuple.dir;
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flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
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rt = (struct rtable *)flow->tuplehash[dir].tuple.dst_cache;
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outdev = rt->dst.dev;
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if (unlikely(nf_flow_exceeds_mtu(skb, flow->tuplehash[dir].tuple.mtu)))
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return NF_ACCEPT;
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if (skb_try_make_writable(skb, sizeof(*iph)))
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return NF_DROP;
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thoff = ip_hdr(skb)->ihl * 4;
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if (nf_flow_state_check(flow, ip_hdr(skb)->protocol, skb, thoff))
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return NF_ACCEPT;
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flow_offload_refresh(flow_table, flow);
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if (nf_flow_offload_dst_check(&rt->dst)) {
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flow_offload_teardown(flow);
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return NF_ACCEPT;
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}
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if (nf_flow_nat_ip(flow, skb, thoff, dir) < 0)
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return NF_DROP;
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iph = ip_hdr(skb);
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ip_decrease_ttl(iph);
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skb->tstamp = 0;
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if (flow_table->flags & NF_FLOWTABLE_COUNTER)
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nf_ct_acct_update(flow->ct, tuplehash->tuple.dir, skb->len);
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if (unlikely(dst_xfrm(&rt->dst))) {
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memset(skb->cb, 0, sizeof(struct inet_skb_parm));
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IPCB(skb)->iif = skb->dev->ifindex;
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IPCB(skb)->flags = IPSKB_FORWARDED;
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return nf_flow_xmit_xfrm(skb, state, &rt->dst);
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}
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skb->dev = outdev;
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nexthop = rt_nexthop(rt, flow->tuplehash[!dir].tuple.src_v4.s_addr);
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skb_dst_set_noref(skb, &rt->dst);
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neigh_xmit(NEIGH_ARP_TABLE, outdev, &nexthop, skb);
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return NF_STOLEN;
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}
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EXPORT_SYMBOL_GPL(nf_flow_offload_ip_hook);
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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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if (skb_try_make_writable(skb, thoff + sizeof(*tcph)))
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return -1;
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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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return 0;
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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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if (skb_try_make_writable(skb, thoff + sizeof(*udph)))
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return -1;
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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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return 0;
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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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return 0;
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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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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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return nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
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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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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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return nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
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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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if (test_bit(NF_FLOW_SNAT, &flow->flags) &&
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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, ipv6_hdr(skb), thoff, dir) < 0))
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return -1;
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ip6h = ipv6_hdr(skb);
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if (test_bit(NF_FLOW_DNAT, &flow->flags) &&
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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, ipv6_hdr(skb), thoff, dir) < 0))
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return -1;
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return 0;
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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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unsigned int thoff, hdrsize;
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struct flow_ports *ports;
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struct ipv6hdr *ip6h;
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if (!pskb_may_pull(skb, sizeof(*ip6h)))
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return -1;
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ip6h = ipv6_hdr(skb);
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switch (ip6h->nexthdr) {
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case IPPROTO_TCP:
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hdrsize = sizeof(struct tcphdr);
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break;
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case IPPROTO_UDP:
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hdrsize = sizeof(struct udphdr);
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break;
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default:
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return -1;
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}
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if (ip6h->hop_limit <= 1)
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return -1;
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thoff = sizeof(*ip6h);
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if (!pskb_may_pull(skb, thoff + hdrsize))
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return -1;
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ip6h = ipv6_hdr(skb);
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ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
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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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return 0;
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}
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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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const struct in6_addr *nexthop;
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struct flow_offload *flow;
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struct net_device *outdev;
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struct ipv6hdr *ip6h;
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struct rt6_info *rt;
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if (skb->protocol != htons(ETH_P_IPV6))
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return NF_ACCEPT;
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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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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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dir = tuplehash->tuple.dir;
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flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
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rt = (struct rt6_info *)flow->tuplehash[dir].tuple.dst_cache;
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outdev = rt->dst.dev;
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if (unlikely(nf_flow_exceeds_mtu(skb, flow->tuplehash[dir].tuple.mtu)))
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return NF_ACCEPT;
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if (nf_flow_state_check(flow, ipv6_hdr(skb)->nexthdr, skb,
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sizeof(*ip6h)))
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return NF_ACCEPT;
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flow_offload_refresh(flow_table, flow);
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if (nf_flow_offload_dst_check(&rt->dst)) {
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flow_offload_teardown(flow);
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return NF_ACCEPT;
|
}
|
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if (skb_try_make_writable(skb, sizeof(*ip6h)))
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return NF_DROP;
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if (nf_flow_nat_ipv6(flow, skb, dir) < 0)
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return NF_DROP;
|
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ip6h = ipv6_hdr(skb);
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ip6h->hop_limit--;
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skb->tstamp = 0;
|
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if (flow_table->flags & NF_FLOWTABLE_COUNTER)
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nf_ct_acct_update(flow->ct, tuplehash->tuple.dir, skb->len);
|
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if (unlikely(dst_xfrm(&rt->dst))) {
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memset(skb->cb, 0, sizeof(struct inet6_skb_parm));
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IP6CB(skb)->iif = skb->dev->ifindex;
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IP6CB(skb)->flags = IP6SKB_FORWARDED;
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return nf_flow_xmit_xfrm(skb, state, &rt->dst);
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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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skb_dst_set_noref(skb, &rt->dst);
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neigh_xmit(NEIGH_ND_TABLE, outdev, nexthop, skb);
|
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return NF_STOLEN;
|
}
|
EXPORT_SYMBOL_GPL(nf_flow_offload_ipv6_hook);
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