// SPDX-License-Identifier: GPL-2.0
/* In-place tunneling */
#include <stdbool.h>
#include <string.h>
#include <linux/stddef.h>
#include <linux/bpf.h>
#include <linux/if_ether.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/mpls.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/pkt_cls.h>
#include <linux/types.h>
#include <bpf/bpf_endian.h>
#include <bpf/bpf_helpers.h>
static const int cfg_port = 8000;
static const int cfg_udp_src = 20000;
#define L2_PAD_SZ (sizeof(struct vxlanhdr) + ETH_HLEN)
#define UDP_PORT 5555
#define MPLS_OVER_UDP_PORT 6635
#define ETH_OVER_UDP_PORT 7777
#define VXLAN_UDP_PORT 8472
#define EXTPROTO_VXLAN 0x1
#define VXLAN_N_VID (1u << 24)
#define VXLAN_VNI_MASK bpf_htonl((VXLAN_N_VID - 1) << 8)
#define VXLAN_FLAGS 0x8
#define VXLAN_VNI 1
#ifndef NEXTHDR_DEST
#define NEXTHDR_DEST 60
#endif
/* MPLS label 1000 with S bit (last label) set and ttl of 255. */
static const __u32 mpls_label = __bpf_constant_htonl(1000 << 12 |
MPLS_LS_S_MASK | 0xff);
struct vxlanhdr {
__be32 vx_flags;
__be32 vx_vni;
} __attribute__((packed));
struct gre_hdr {
__be16 flags;
__be16 protocol;
} __attribute__((packed));
union l4hdr {
struct udphdr udp;
struct gre_hdr gre;
};
struct v4hdr {
struct iphdr ip;
union l4hdr l4hdr;
__u8 pad[L2_PAD_SZ]; /* space for L2 header / vxlan header ... */
} __attribute__((packed));
struct v6hdr {
struct ipv6hdr ip;
union l4hdr l4hdr;
__u8 pad[L2_PAD_SZ]; /* space for L2 header / vxlan header ... */
} __attribute__((packed));
static __always_inline void set_ipv4_csum(struct iphdr *iph)
{
__u16 *iph16 = (__u16 *)iph;
__u32 csum;
int i;
iph->check = 0;
#pragma clang loop unroll(full)
for (i = 0, csum = 0; i < sizeof(*iph) >> 1; i++)
csum += *iph16++;
iph->check = ~((csum & 0xffff) + (csum >> 16));
}
static __always_inline int __encap_ipv4(struct __sk_buff *skb, __u8 encap_proto,
__u16 l2_proto, __u16 ext_proto)
{
__u16 udp_dst = UDP_PORT;
struct iphdr iph_inner;
struct v4hdr h_outer;
struct tcphdr tcph;
int olen, l2_len;
__u8 *l2_hdr = NULL;
int tcp_off;
__u64 flags;
/* Most tests encapsulate a packet into a tunnel with the same
* network protocol, and derive the outer header fields from
* the inner header.
*
* The 6in4 case tests different inner and outer protocols. As
* the inner is ipv6, but the outer expects an ipv4 header as
* input, manually build a struct iphdr based on the ipv6hdr.
*/
if (encap_proto == IPPROTO_IPV6) {
const __u32 saddr = (192 << 24) | (168 << 16) | (1 << 8) | 1;
const __u32 daddr = (192 << 24) | (168 << 16) | (1 << 8) | 2;
struct ipv6hdr iph6_inner;
/* Read the IPv6 header */
if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph6_inner,
sizeof(iph6_inner)) < 0)
return TC_ACT_OK;
/* Derive the IPv4 header fields from the IPv6 header */
memset(&iph_inner, 0, sizeof(iph_inner));
iph_inner.version = 4;
iph_inner.ihl = 5;
iph_inner.tot_len = bpf_htons(sizeof(iph6_inner) +
bpf_ntohs(iph6_inner.payload_len));
iph_inner.ttl = iph6_inner.hop_limit - 1;
iph_inner.protocol = iph6_inner.nexthdr;
iph_inner.saddr = __bpf_constant_htonl(saddr);
iph_inner.daddr = __bpf_constant_htonl(daddr);
tcp_off = sizeof(iph6_inner);
} else {
if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_inner,
sizeof(iph_inner)) < 0)
return TC_ACT_OK;
tcp_off = sizeof(iph_inner);
}
/* filter only packets we want */
if (iph_inner.ihl != 5 || iph_inner.protocol != IPPROTO_TCP)
return TC_ACT_OK;
if (bpf_skb_load_bytes(skb, ETH_HLEN + tcp_off,
&tcph, sizeof(tcph)) < 0)
return TC_ACT_OK;
if (tcph.dest != __bpf_constant_htons(cfg_port))
return TC_ACT_OK;
olen = sizeof(h_outer.ip);
l2_len = 0;
flags = BPF_F_ADJ_ROOM_FIXED_GSO | BPF_F_ADJ_ROOM_ENCAP_L3_IPV4;
switch (l2_proto) {
case ETH_P_MPLS_UC:
l2_len = sizeof(mpls_label);
udp_dst = MPLS_OVER_UDP_PORT;
break;
case ETH_P_TEB:
l2_len = ETH_HLEN;
if (ext_proto & EXTPROTO_VXLAN) {
udp_dst = VXLAN_UDP_PORT;
l2_len += sizeof(struct vxlanhdr);
} else
udp_dst = ETH_OVER_UDP_PORT;
break;
}
flags |= BPF_F_ADJ_ROOM_ENCAP_L2(l2_len);
switch (encap_proto) {
case IPPROTO_GRE:
flags |= BPF_F_ADJ_ROOM_ENCAP_L4_GRE;
olen += sizeof(h_outer.l4hdr.gre);
h_outer.l4hdr.gre.protocol = bpf_htons(l2_proto);
h_outer.l4hdr.gre.flags = 0;
break;
case IPPROTO_UDP:
flags |= BPF_F_ADJ_ROOM_ENCAP_L4_UDP;
olen += sizeof(h_outer.l4hdr.udp);
h_outer.l4hdr.udp.source = __bpf_constant_htons(cfg_udp_src);
h_outer.l4hdr.udp.dest = bpf_htons(udp_dst);
h_outer.l4hdr.udp.check = 0;
h_outer.l4hdr.udp.len = bpf_htons(bpf_ntohs(iph_inner.tot_len) +
sizeof(h_outer.l4hdr.udp) +
l2_len);
break;
case IPPROTO_IPIP:
case IPPROTO_IPV6:
break;
default:
return TC_ACT_OK;
}
/* add L2 encap (if specified) */
l2_hdr = (__u8 *)&h_outer + olen;
switch (l2_proto) {
case ETH_P_MPLS_UC:
*(__u32 *)l2_hdr = mpls_label;
break;
case ETH_P_TEB:
flags |= BPF_F_ADJ_ROOM_ENCAP_L2_ETH;
if (ext_proto & EXTPROTO_VXLAN) {
struct vxlanhdr *vxlan_hdr = (struct vxlanhdr *)l2_hdr;
vxlan_hdr->vx_flags = VXLAN_FLAGS;
vxlan_hdr->vx_vni = bpf_htonl((VXLAN_VNI & VXLAN_VNI_MASK) << 8);
l2_hdr += sizeof(struct vxlanhdr);
}
if (bpf_skb_load_bytes(skb, 0, l2_hdr, ETH_HLEN))
return TC_ACT_SHOT;
break;
}
olen += l2_len;
/* add room between mac and network header */
if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, flags))
return TC_ACT_SHOT;
/* prepare new outer network header */
h_outer.ip = iph_inner;
h_outer.ip.tot_len = bpf_htons(olen +
bpf_ntohs(h_outer.ip.tot_len));
h_outer.ip.protocol = encap_proto;
set_ipv4_csum((void *)&h_outer.ip);
/* store new outer network header */
if (bpf_skb_store_bytes(skb, ETH_HLEN, &h_outer, olen,
BPF_F_INVALIDATE_HASH) < 0)
return TC_ACT_SHOT;
/* if changing outer proto type, update eth->h_proto */
if (encap_proto == IPPROTO_IPV6) {
struct ethhdr eth;
if (bpf_skb_load_bytes(skb, 0, ð, sizeof(eth)) < 0)
return TC_ACT_SHOT;
eth.h_proto = bpf_htons(ETH_P_IP);
if (bpf_skb_store_bytes(skb, 0, ð, sizeof(eth), 0) < 0)
return TC_ACT_SHOT;
}
return TC_ACT_OK;
}
static __always_inline int encap_ipv4(struct __sk_buff *skb, __u8 encap_proto,
__u16 l2_proto)
{
return __encap_ipv4(skb, encap_proto, l2_proto, 0);
}
static __always_inline int __encap_ipv6(struct __sk_buff *skb, __u8 encap_proto,
__u16 l2_proto, __u16 ext_proto)
{
__u16 udp_dst = UDP_PORT;
struct ipv6hdr iph_inner;
struct v6hdr h_outer;
struct tcphdr tcph;
int olen, l2_len;
__u8 *l2_hdr = NULL;
__u16 tot_len;
__u64 flags;
if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_inner,
sizeof(iph_inner)) < 0)
return TC_ACT_OK;
/* filter only packets we want */
if (bpf_skb_load_bytes(skb, ETH_HLEN + sizeof(iph_inner),
&tcph, sizeof(tcph)) < 0)
return TC_ACT_OK;
if (tcph.dest != __bpf_constant_htons(cfg_port))
return TC_ACT_OK;
olen = sizeof(h_outer.ip);
l2_len = 0;
flags = BPF_F_ADJ_ROOM_FIXED_GSO | BPF_F_ADJ_ROOM_ENCAP_L3_IPV6;
switch (l2_proto) {
case ETH_P_MPLS_UC:
l2_len = sizeof(mpls_label);
udp_dst = MPLS_OVER_UDP_PORT;
break;
case ETH_P_TEB:
l2_len = ETH_HLEN;
if (ext_proto & EXTPROTO_VXLAN) {
udp_dst = VXLAN_UDP_PORT;
l2_len += sizeof(struct vxlanhdr);
} else
udp_dst = ETH_OVER_UDP_PORT;
break;
}
flags |= BPF_F_ADJ_ROOM_ENCAP_L2(l2_len);
switch (encap_proto) {
case IPPROTO_GRE:
flags |= BPF_F_ADJ_ROOM_ENCAP_L4_GRE;
olen += sizeof(h_outer.l4hdr.gre);
h_outer.l4hdr.gre.protocol = bpf_htons(l2_proto);
h_outer.l4hdr.gre.flags = 0;
break;
case IPPROTO_UDP:
flags |= BPF_F_ADJ_ROOM_ENCAP_L4_UDP;
olen += sizeof(h_outer.l4hdr.udp);
h_outer.l4hdr.udp.source = __bpf_constant_htons(cfg_udp_src);
h_outer.l4hdr.udp.dest = bpf_htons(udp_dst);
tot_len = bpf_ntohs(iph_inner.payload_len) + sizeof(iph_inner) +
sizeof(h_outer.l4hdr.udp) + l2_len;
h_outer.l4hdr.udp.check = 0;
h_outer.l4hdr.udp.len = bpf_htons(tot_len);
break;
case IPPROTO_IPV6:
break;
default:
return TC_ACT_OK;
}
/* add L2 encap (if specified) */
l2_hdr = (__u8 *)&h_outer + olen;
switch (l2_proto) {
case ETH_P_MPLS_UC:
*(__u32 *)l2_hdr = mpls_label;
break;
case ETH_P_TEB:
flags |= BPF_F_ADJ_ROOM_ENCAP_L2_ETH;
if (ext_proto & EXTPROTO_VXLAN) {
struct vxlanhdr *vxlan_hdr = (struct vxlanhdr *)l2_hdr;
vxlan_hdr->vx_flags = VXLAN_FLAGS;
vxlan_hdr->vx_vni = bpf_htonl((VXLAN_VNI & VXLAN_VNI_MASK) << 8);
l2_hdr += sizeof(struct vxlanhdr);
}
if (bpf_skb_load_bytes(skb, 0, l2_hdr, ETH_HLEN))
return TC_ACT_SHOT;
break;
}
olen += l2_len;
/* add room between mac and network header */
if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, flags))
return TC_ACT_SHOT;
/* prepare new outer network header */
h_outer.ip = iph_inner;
h_outer.ip.payload_len = bpf_htons(olen +
bpf_ntohs(h_outer.ip.payload_len));
h_outer.ip.nexthdr = encap_proto;
/* store new outer network header */
if (bpf_skb_store_bytes(skb, ETH_HLEN, &h_outer, olen,
BPF_F_INVALIDATE_HASH) < 0)
return TC_ACT_SHOT;
return TC_ACT_OK;
}
static int encap_ipv6_ipip6(struct __sk_buff *skb)
{
struct iphdr iph_inner;
struct v6hdr h_outer;
struct tcphdr tcph;
struct ethhdr eth;
__u64 flags;
int olen;
if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_inner,
sizeof(iph_inner)) < 0)
return TC_ACT_OK;
/* filter only packets we want */
if (bpf_skb_load_bytes(skb, ETH_HLEN + (iph_inner.ihl << 2),
&tcph, sizeof(tcph)) < 0)
return TC_ACT_OK;
if (tcph.dest != __bpf_constant_htons(cfg_port))
return TC_ACT_OK;
olen = sizeof(h_outer.ip);
flags = BPF_F_ADJ_ROOM_FIXED_GSO | BPF_F_ADJ_ROOM_ENCAP_L3_IPV6;
/* add room between mac and network header */
if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, flags))
return TC_ACT_SHOT;
/* prepare new outer network header */
memset(&h_outer.ip, 0, sizeof(h_outer.ip));
h_outer.ip.version = 6;
h_outer.ip.hop_limit = iph_inner.ttl;
h_outer.ip.saddr.s6_addr[1] = 0xfd;
h_outer.ip.saddr.s6_addr[15] = 1;
h_outer.ip.daddr.s6_addr[1] = 0xfd;
h_outer.ip.daddr.s6_addr[15] = 2;
h_outer.ip.payload_len = iph_inner.tot_len;
h_outer.ip.nexthdr = IPPROTO_IPIP;
/* store new outer network header */
if (bpf_skb_store_bytes(skb, ETH_HLEN, &h_outer, olen,
BPF_F_INVALIDATE_HASH) < 0)
return TC_ACT_SHOT;
/* update eth->h_proto */
if (bpf_skb_load_bytes(skb, 0, ð, sizeof(eth)) < 0)
return TC_ACT_SHOT;
eth.h_proto = bpf_htons(ETH_P_IPV6);
if (bpf_skb_store_bytes(skb, 0, ð, sizeof(eth), 0) < 0)
return TC_ACT_SHOT;
return TC_ACT_OK;
}
static __always_inline int encap_ipv6(struct __sk_buff *skb, __u8 encap_proto,
__u16 l2_proto)
{
return __encap_ipv6(skb, encap_proto, l2_proto, 0);
}
SEC("encap_ipip_none")
int __encap_ipip_none(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
return encap_ipv4(skb, IPPROTO_IPIP, ETH_P_IP);
else
return TC_ACT_OK;
}
SEC("encap_gre_none")
int __encap_gre_none(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
return encap_ipv4(skb, IPPROTO_GRE, ETH_P_IP);
else
return TC_ACT_OK;
}
SEC("encap_gre_mpls")
int __encap_gre_mpls(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
return encap_ipv4(skb, IPPROTO_GRE, ETH_P_MPLS_UC);
else
return TC_ACT_OK;
}
SEC("encap_gre_eth")
int __encap_gre_eth(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
return encap_ipv4(skb, IPPROTO_GRE, ETH_P_TEB);
else
return TC_ACT_OK;
}
SEC("encap_udp_none")
int __encap_udp_none(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
return encap_ipv4(skb, IPPROTO_UDP, ETH_P_IP);
else
return TC_ACT_OK;
}
SEC("encap_udp_mpls")
int __encap_udp_mpls(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
return encap_ipv4(skb, IPPROTO_UDP, ETH_P_MPLS_UC);
else
return TC_ACT_OK;
}
SEC("encap_udp_eth")
int __encap_udp_eth(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
return encap_ipv4(skb, IPPROTO_UDP, ETH_P_TEB);
else
return TC_ACT_OK;
}
SEC("encap_vxlan_eth")
int __encap_vxlan_eth(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
return __encap_ipv4(skb, IPPROTO_UDP,
ETH_P_TEB,
EXTPROTO_VXLAN);
else
return TC_ACT_OK;
}
SEC("encap_sit_none")
int __encap_sit_none(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
return encap_ipv4(skb, IPPROTO_IPV6, ETH_P_IP);
else
return TC_ACT_OK;
}
SEC("encap_ip6tnl_none")
int __encap_ip6tnl_none(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
return encap_ipv6(skb, IPPROTO_IPV6, ETH_P_IPV6);
else
return TC_ACT_OK;
}
SEC("encap_ipip6_none")
int __encap_ipip6_none(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
return encap_ipv6_ipip6(skb);
else
return TC_ACT_OK;
}
SEC("encap_ip6gre_none")
int __encap_ip6gre_none(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
return encap_ipv6(skb, IPPROTO_GRE, ETH_P_IPV6);
else
return TC_ACT_OK;
}
SEC("encap_ip6gre_mpls")
int __encap_ip6gre_mpls(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
return encap_ipv6(skb, IPPROTO_GRE, ETH_P_MPLS_UC);
else
return TC_ACT_OK;
}
SEC("encap_ip6gre_eth")
int __encap_ip6gre_eth(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
return encap_ipv6(skb, IPPROTO_GRE, ETH_P_TEB);
else
return TC_ACT_OK;
}
SEC("encap_ip6udp_none")
int __encap_ip6udp_none(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
return encap_ipv6(skb, IPPROTO_UDP, ETH_P_IPV6);
else
return TC_ACT_OK;
}
SEC("encap_ip6udp_mpls")
int __encap_ip6udp_mpls(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
return encap_ipv6(skb, IPPROTO_UDP, ETH_P_MPLS_UC);
else
return TC_ACT_OK;
}
SEC("encap_ip6udp_eth")
int __encap_ip6udp_eth(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
return encap_ipv6(skb, IPPROTO_UDP, ETH_P_TEB);
else
return TC_ACT_OK;
}
SEC("encap_ip6vxlan_eth")
int __encap_ip6vxlan_eth(struct __sk_buff *skb)
{
if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
return __encap_ipv6(skb, IPPROTO_UDP,
ETH_P_TEB,
EXTPROTO_VXLAN);
else
return TC_ACT_OK;
}
static int decap_internal(struct __sk_buff *skb, int off, int len, char proto)
{
__u64 flags = BPF_F_ADJ_ROOM_FIXED_GSO;
struct ipv6_opt_hdr ip6_opt_hdr;
struct gre_hdr greh;
struct udphdr udph;
int olen = len;
switch (proto) {
case IPPROTO_IPIP:
flags |= BPF_F_ADJ_ROOM_DECAP_L3_IPV4;
break;
case IPPROTO_IPV6:
flags |= BPF_F_ADJ_ROOM_DECAP_L3_IPV6;
break;
case NEXTHDR_DEST:
if (bpf_skb_load_bytes(skb, off + len, &ip6_opt_hdr,
sizeof(ip6_opt_hdr)) < 0)
return TC_ACT_OK;
switch (ip6_opt_hdr.nexthdr) {
case IPPROTO_IPIP:
flags |= BPF_F_ADJ_ROOM_DECAP_L3_IPV4;
break;
case IPPROTO_IPV6:
flags |= BPF_F_ADJ_ROOM_DECAP_L3_IPV6;
break;
default:
return TC_ACT_OK;
}
break;
case IPPROTO_GRE:
olen += sizeof(struct gre_hdr);
if (bpf_skb_load_bytes(skb, off + len, &greh, sizeof(greh)) < 0)
return TC_ACT_OK;
switch (bpf_ntohs(greh.protocol)) {
case ETH_P_MPLS_UC:
olen += sizeof(mpls_label);
break;
case ETH_P_TEB:
olen += ETH_HLEN;
break;
}
break;
case IPPROTO_UDP:
olen += sizeof(struct udphdr);
if (bpf_skb_load_bytes(skb, off + len, &udph, sizeof(udph)) < 0)
return TC_ACT_OK;
switch (bpf_ntohs(udph.dest)) {
case MPLS_OVER_UDP_PORT:
olen += sizeof(mpls_label);
break;
case ETH_OVER_UDP_PORT:
olen += ETH_HLEN;
break;
case VXLAN_UDP_PORT:
olen += ETH_HLEN + sizeof(struct vxlanhdr);
break;
}
break;
default:
return TC_ACT_OK;
}
if (bpf_skb_adjust_room(skb, -olen, BPF_ADJ_ROOM_MAC, flags))
return TC_ACT_SHOT;
return TC_ACT_OK;
}
static int decap_ipv4(struct __sk_buff *skb)
{
struct iphdr iph_outer;
if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_outer,
sizeof(iph_outer)) < 0)
return TC_ACT_OK;
if (iph_outer.ihl != 5)
return TC_ACT_OK;
return decap_internal(skb, ETH_HLEN, sizeof(iph_outer),
iph_outer.protocol);
}
static int decap_ipv6(struct __sk_buff *skb)
{
struct ipv6hdr iph_outer;
if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_outer,
sizeof(iph_outer)) < 0)
return TC_ACT_OK;
return decap_internal(skb, ETH_HLEN, sizeof(iph_outer),
iph_outer.nexthdr);
}
SEC("decap")
int decap_f(struct __sk_buff *skb)
{
switch (skb->protocol) {
case __bpf_constant_htons(ETH_P_IP):
return decap_ipv4(skb);
case __bpf_constant_htons(ETH_P_IPV6):
return decap_ipv6(skb);
default:
/* does not match, ignore */
return TC_ACT_OK;
}
}
char __license[] SEC("license") = "GPL";
