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