bpf/progs/test_tc_tunnel.c

0001 // SPDX-License-Identifier: GPL-2.0
0002
0003 /* In-place tunneling */
0004
0005 #include <stdbool.h>
0006 #include <string.h>
0007
0008 #include <linux/stddef.h>
0009 #include <linux/bpf.h>
0010 #include <linux/if_ether.h>
0011 #include <linux/in.h>
0012 #include <linux/ip.h>
0013 #include <linux/ipv6.h>
0014 #include <linux/mpls.h>
0015 #include <linux/tcp.h>
0016 #include <linux/udp.h>
0017 #include <linux/pkt_cls.h>
0018 #include <linux/types.h>
0019
0020 #include <bpf/bpf_endian.h>
0021 #include <bpf/bpf_helpers.h>
0022
0023 static const int cfg_port = 8000;
0024
0025 static const int cfg_udp_src = 20000;
0026
0027 #define L2_PAD_SZ   (sizeof(struct vxlanhdr) + ETH_HLEN)
0028
0029 #define UDP_PORT        5555
0030 #define MPLS_OVER_UDP_PORT  6635
0031 #define ETH_OVER_UDP_PORT   7777
0032 #define VXLAN_UDP_PORT      8472
0033
0034 #define EXTPROTO_VXLAN  0x1
0035
0036 #define VXLAN_N_VID     (1u << 24)
0037 #define VXLAN_VNI_MASK  bpf_htonl((VXLAN_N_VID - 1) << 8)
0038 #define VXLAN_FLAGS     0x8
0039 #define VXLAN_VNI       1
0040
0041 /* MPLS label 1000 with S bit (last label) set and ttl of 255. */
0042 static const __u32 mpls_label = __bpf_constant_htonl(1000 << 12 |
0043                              MPLS_LS_S_MASK | 0xff);
0044
0045 struct vxlanhdr {
0046     __be32 vx_flags;
0047     __be32 vx_vni;
0048 } __attribute__((packed));
0049
0050 struct gre_hdr {
0051     __be16 flags;
0052     __be16 protocol;
0053 } __attribute__((packed));
0054
0055 union l4hdr {
0056     struct udphdr udp;
0057     struct gre_hdr gre;
0058 };
0059
0060 struct v4hdr {
0061     struct iphdr ip;
0062     union l4hdr l4hdr;
0063     __u8 pad[L2_PAD_SZ];        /* space for L2 header / vxlan header ... */
0064 } __attribute__((packed));
0065
0066 struct v6hdr {
0067     struct ipv6hdr ip;
0068     union l4hdr l4hdr;
0069     __u8 pad[L2_PAD_SZ];        /* space for L2 header / vxlan header ... */
0070 } __attribute__((packed));
0071
0072 static __always_inline void set_ipv4_csum(struct iphdr *iph)
0073 {
0074     __u16 *iph16 = (__u16 *)iph;
0075     __u32 csum;
0076     int i;
0077
0078     iph->check = 0;
0079
0080 #pragma clang loop unroll(full)
0081     for (i = 0, csum = 0; i < sizeof(*iph) >> 1; i++)
0082         csum += *iph16++;
0083
0084     iph->check = ~((csum & 0xffff) + (csum >> 16));
0085 }
0086
0087 static __always_inline int __encap_ipv4(struct __sk_buff *skb, __u8 encap_proto,
0088                     __u16 l2_proto, __u16 ext_proto)
0089 {
0090     __u16 udp_dst = UDP_PORT;
0091     struct iphdr iph_inner;
0092     struct v4hdr h_outer;
0093     struct tcphdr tcph;
0094     int olen, l2_len;
0095     __u8 *l2_hdr = NULL;
0096     int tcp_off;
0097     __u64 flags;
0098
0099     /* Most tests encapsulate a packet into a tunnel with the same
0100      * network protocol, and derive the outer header fields from
0101      * the inner header.
0102      *
0103      * The 6in4 case tests different inner and outer protocols. As
0104      * the inner is ipv6, but the outer expects an ipv4 header as
0105      * input, manually build a struct iphdr based on the ipv6hdr.
0106      */
0107     if (encap_proto == IPPROTO_IPV6) {
0108         const __u32 saddr = (192 << 24) | (168 << 16) | (1 << 8) | 1;
0109         const __u32 daddr = (192 << 24) | (168 << 16) | (1 << 8) | 2;
0110         struct ipv6hdr iph6_inner;
0111
0112         /* Read the IPv6 header */
0113         if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph6_inner,
0114                        sizeof(iph6_inner)) < 0)
0115             return TC_ACT_OK;
0116
0117         /* Derive the IPv4 header fields from the IPv6 header */
0118         memset(&iph_inner, 0, sizeof(iph_inner));
0119         iph_inner.version = 4;
0120         iph_inner.ihl = 5;
0121         iph_inner.tot_len = bpf_htons(sizeof(iph6_inner) +
0122                     bpf_ntohs(iph6_inner.payload_len));
0123         iph_inner.ttl = iph6_inner.hop_limit - 1;
0124         iph_inner.protocol = iph6_inner.nexthdr;
0125         iph_inner.saddr = __bpf_constant_htonl(saddr);
0126         iph_inner.daddr = __bpf_constant_htonl(daddr);
0127
0128         tcp_off = sizeof(iph6_inner);
0129     } else {
0130         if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_inner,
0131                        sizeof(iph_inner)) < 0)
0132             return TC_ACT_OK;
0133
0134         tcp_off = sizeof(iph_inner);
0135     }
0136
0137     /* filter only packets we want */
0138     if (iph_inner.ihl != 5 || iph_inner.protocol != IPPROTO_TCP)
0139         return TC_ACT_OK;
0140
0141     if (bpf_skb_load_bytes(skb, ETH_HLEN + tcp_off,
0142                    &tcph, sizeof(tcph)) < 0)
0143         return TC_ACT_OK;
0144
0145     if (tcph.dest != __bpf_constant_htons(cfg_port))
0146         return TC_ACT_OK;
0147
0148     olen = sizeof(h_outer.ip);
0149     l2_len = 0;
0150
0151     flags = BPF_F_ADJ_ROOM_FIXED_GSO | BPF_F_ADJ_ROOM_ENCAP_L3_IPV4;
0152
0153     switch (l2_proto) {
0154     case ETH_P_MPLS_UC:
0155         l2_len = sizeof(mpls_label);
0156         udp_dst = MPLS_OVER_UDP_PORT;
0157         break;
0158     case ETH_P_TEB:
0159         l2_len = ETH_HLEN;
0160         if (ext_proto & EXTPROTO_VXLAN) {
0161             udp_dst = VXLAN_UDP_PORT;
0162             l2_len += sizeof(struct vxlanhdr);
0163         } else
0164             udp_dst = ETH_OVER_UDP_PORT;
0165         break;
0166     }
0167     flags |= BPF_F_ADJ_ROOM_ENCAP_L2(l2_len);
0168
0169     switch (encap_proto) {
0170     case IPPROTO_GRE:
0171         flags |= BPF_F_ADJ_ROOM_ENCAP_L4_GRE;
0172         olen += sizeof(h_outer.l4hdr.gre);
0173         h_outer.l4hdr.gre.protocol = bpf_htons(l2_proto);
0174         h_outer.l4hdr.gre.flags = 0;
0175         break;
0176     case IPPROTO_UDP:
0177         flags |= BPF_F_ADJ_ROOM_ENCAP_L4_UDP;
0178         olen += sizeof(h_outer.l4hdr.udp);
0179         h_outer.l4hdr.udp.source = __bpf_constant_htons(cfg_udp_src);
0180         h_outer.l4hdr.udp.dest = bpf_htons(udp_dst);
0181         h_outer.l4hdr.udp.check = 0;
0182         h_outer.l4hdr.udp.len = bpf_htons(bpf_ntohs(iph_inner.tot_len) +
0183                           sizeof(h_outer.l4hdr.udp) +
0184                           l2_len);
0185         break;
0186     case IPPROTO_IPIP:
0187     case IPPROTO_IPV6:
0188         break;
0189     default:
0190         return TC_ACT_OK;
0191     }
0192
0193     /* add L2 encap (if specified) */
0194     l2_hdr = (__u8 *)&h_outer + olen;
0195     switch (l2_proto) {
0196     case ETH_P_MPLS_UC:
0197         *(__u32 *)l2_hdr = mpls_label;
0198         break;
0199     case ETH_P_TEB:
0200         flags |= BPF_F_ADJ_ROOM_ENCAP_L2_ETH;
0201
0202         if (ext_proto & EXTPROTO_VXLAN) {
0203             struct vxlanhdr *vxlan_hdr = (struct vxlanhdr *)l2_hdr;
0204
0205             vxlan_hdr->vx_flags = VXLAN_FLAGS;
0206             vxlan_hdr->vx_vni = bpf_htonl((VXLAN_VNI & VXLAN_VNI_MASK) << 8);
0207
0208             l2_hdr += sizeof(struct vxlanhdr);
0209         }
0210
0211         if (bpf_skb_load_bytes(skb, 0, l2_hdr, ETH_HLEN))
0212             return TC_ACT_SHOT;
0213
0214         break;
0215     }
0216     olen += l2_len;
0217
0218     /* add room between mac and network header */
0219     if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, flags))
0220         return TC_ACT_SHOT;
0221
0222     /* prepare new outer network header */
0223     h_outer.ip = iph_inner;
0224     h_outer.ip.tot_len = bpf_htons(olen +
0225                        bpf_ntohs(h_outer.ip.tot_len));
0226     h_outer.ip.protocol = encap_proto;
0227
0228     set_ipv4_csum((void *)&h_outer.ip);
0229
0230     /* store new outer network header */
0231     if (bpf_skb_store_bytes(skb, ETH_HLEN, &h_outer, olen,
0232                 BPF_F_INVALIDATE_HASH) < 0)
0233         return TC_ACT_SHOT;
0234
0235     /* if changing outer proto type, update eth->h_proto */
0236     if (encap_proto == IPPROTO_IPV6) {
0237         struct ethhdr eth;
0238
0239         if (bpf_skb_load_bytes(skb, 0, &eth, sizeof(eth)) < 0)
0240             return TC_ACT_SHOT;
0241         eth.h_proto = bpf_htons(ETH_P_IP);
0242         if (bpf_skb_store_bytes(skb, 0, &eth, sizeof(eth), 0) < 0)
0243             return TC_ACT_SHOT;
0244     }
0245
0246     return TC_ACT_OK;
0247 }
0248
0249 static __always_inline int encap_ipv4(struct __sk_buff *skb, __u8 encap_proto,
0250                       __u16 l2_proto)
0251 {
0252     return __encap_ipv4(skb, encap_proto, l2_proto, 0);
0253 }
0254
0255 static __always_inline int __encap_ipv6(struct __sk_buff *skb, __u8 encap_proto,
0256                     __u16 l2_proto, __u16 ext_proto)
0257 {
0258     __u16 udp_dst = UDP_PORT;
0259     struct ipv6hdr iph_inner;
0260     struct v6hdr h_outer;
0261     struct tcphdr tcph;
0262     int olen, l2_len;
0263     __u8 *l2_hdr = NULL;
0264     __u16 tot_len;
0265     __u64 flags;
0266
0267     if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_inner,
0268                    sizeof(iph_inner)) < 0)
0269         return TC_ACT_OK;
0270
0271     /* filter only packets we want */
0272     if (bpf_skb_load_bytes(skb, ETH_HLEN + sizeof(iph_inner),
0273                    &tcph, sizeof(tcph)) < 0)
0274         return TC_ACT_OK;
0275
0276     if (tcph.dest != __bpf_constant_htons(cfg_port))
0277         return TC_ACT_OK;
0278
0279     olen = sizeof(h_outer.ip);
0280     l2_len = 0;
0281
0282     flags = BPF_F_ADJ_ROOM_FIXED_GSO | BPF_F_ADJ_ROOM_ENCAP_L3_IPV6;
0283
0284     switch (l2_proto) {
0285     case ETH_P_MPLS_UC:
0286         l2_len = sizeof(mpls_label);
0287         udp_dst = MPLS_OVER_UDP_PORT;
0288         break;
0289     case ETH_P_TEB:
0290         l2_len = ETH_HLEN;
0291         if (ext_proto & EXTPROTO_VXLAN) {
0292             udp_dst = VXLAN_UDP_PORT;
0293             l2_len += sizeof(struct vxlanhdr);
0294         } else
0295             udp_dst = ETH_OVER_UDP_PORT;
0296         break;
0297     }
0298     flags |= BPF_F_ADJ_ROOM_ENCAP_L2(l2_len);
0299
0300     switch (encap_proto) {
0301     case IPPROTO_GRE:
0302         flags |= BPF_F_ADJ_ROOM_ENCAP_L4_GRE;
0303         olen += sizeof(h_outer.l4hdr.gre);
0304         h_outer.l4hdr.gre.protocol = bpf_htons(l2_proto);
0305         h_outer.l4hdr.gre.flags = 0;
0306         break;
0307     case IPPROTO_UDP:
0308         flags |= BPF_F_ADJ_ROOM_ENCAP_L4_UDP;
0309         olen += sizeof(h_outer.l4hdr.udp);
0310         h_outer.l4hdr.udp.source = __bpf_constant_htons(cfg_udp_src);
0311         h_outer.l4hdr.udp.dest = bpf_htons(udp_dst);
0312         tot_len = bpf_ntohs(iph_inner.payload_len) + sizeof(iph_inner) +
0313               sizeof(h_outer.l4hdr.udp) + l2_len;
0314         h_outer.l4hdr.udp.check = 0;
0315         h_outer.l4hdr.udp.len = bpf_htons(tot_len);
0316         break;
0317     case IPPROTO_IPV6:
0318         break;
0319     default:
0320         return TC_ACT_OK;
0321     }
0322
0323     /* add L2 encap (if specified) */
0324     l2_hdr = (__u8 *)&h_outer + olen;
0325     switch (l2_proto) {
0326     case ETH_P_MPLS_UC:
0327         *(__u32 *)l2_hdr = mpls_label;
0328         break;
0329     case ETH_P_TEB:
0330         flags |= BPF_F_ADJ_ROOM_ENCAP_L2_ETH;
0331
0332         if (ext_proto & EXTPROTO_VXLAN) {
0333             struct vxlanhdr *vxlan_hdr = (struct vxlanhdr *)l2_hdr;
0334
0335             vxlan_hdr->vx_flags = VXLAN_FLAGS;
0336             vxlan_hdr->vx_vni = bpf_htonl((VXLAN_VNI & VXLAN_VNI_MASK) << 8);
0337
0338             l2_hdr += sizeof(struct vxlanhdr);
0339         }
0340
0341         if (bpf_skb_load_bytes(skb, 0, l2_hdr, ETH_HLEN))
0342             return TC_ACT_SHOT;
0343         break;
0344     }
0345     olen += l2_len;
0346
0347     /* add room between mac and network header */
0348     if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, flags))
0349         return TC_ACT_SHOT;
0350
0351     /* prepare new outer network header */
0352     h_outer.ip = iph_inner;
0353     h_outer.ip.payload_len = bpf_htons(olen +
0354                        bpf_ntohs(h_outer.ip.payload_len));
0355
0356     h_outer.ip.nexthdr = encap_proto;
0357
0358     /* store new outer network header */
0359     if (bpf_skb_store_bytes(skb, ETH_HLEN, &h_outer, olen,
0360                 BPF_F_INVALIDATE_HASH) < 0)
0361         return TC_ACT_SHOT;
0362
0363     return TC_ACT_OK;
0364 }
0365
0366 static __always_inline int encap_ipv6(struct __sk_buff *skb, __u8 encap_proto,
0367                       __u16 l2_proto)
0368 {
0369     return __encap_ipv6(skb, encap_proto, l2_proto, 0);
0370 }
0371
0372 SEC("encap_ipip_none")
0373 int __encap_ipip_none(struct __sk_buff *skb)
0374 {
0375     if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
0376         return encap_ipv4(skb, IPPROTO_IPIP, ETH_P_IP);
0377     else
0378         return TC_ACT_OK;
0379 }
0380
0381 SEC("encap_gre_none")
0382 int __encap_gre_none(struct __sk_buff *skb)
0383 {
0384     if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
0385         return encap_ipv4(skb, IPPROTO_GRE, ETH_P_IP);
0386     else
0387         return TC_ACT_OK;
0388 }
0389
0390 SEC("encap_gre_mpls")
0391 int __encap_gre_mpls(struct __sk_buff *skb)
0392 {
0393     if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
0394         return encap_ipv4(skb, IPPROTO_GRE, ETH_P_MPLS_UC);
0395     else
0396         return TC_ACT_OK;
0397 }
0398
0399 SEC("encap_gre_eth")
0400 int __encap_gre_eth(struct __sk_buff *skb)
0401 {
0402     if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
0403         return encap_ipv4(skb, IPPROTO_GRE, ETH_P_TEB);
0404     else
0405         return TC_ACT_OK;
0406 }
0407
0408 SEC("encap_udp_none")
0409 int __encap_udp_none(struct __sk_buff *skb)
0410 {
0411     if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
0412         return encap_ipv4(skb, IPPROTO_UDP, ETH_P_IP);
0413     else
0414         return TC_ACT_OK;
0415 }
0416
0417 SEC("encap_udp_mpls")
0418 int __encap_udp_mpls(struct __sk_buff *skb)
0419 {
0420     if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
0421         return encap_ipv4(skb, IPPROTO_UDP, ETH_P_MPLS_UC);
0422     else
0423         return TC_ACT_OK;
0424 }
0425
0426 SEC("encap_udp_eth")
0427 int __encap_udp_eth(struct __sk_buff *skb)
0428 {
0429     if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
0430         return encap_ipv4(skb, IPPROTO_UDP, ETH_P_TEB);
0431     else
0432         return TC_ACT_OK;
0433 }
0434
0435 SEC("encap_vxlan_eth")
0436 int __encap_vxlan_eth(struct __sk_buff *skb)
0437 {
0438     if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
0439         return __encap_ipv4(skb, IPPROTO_UDP,
0440                     ETH_P_TEB,
0441                     EXTPROTO_VXLAN);
0442     else
0443         return TC_ACT_OK;
0444 }
0445
0446 SEC("encap_sit_none")
0447 int __encap_sit_none(struct __sk_buff *skb)
0448 {
0449     if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
0450         return encap_ipv4(skb, IPPROTO_IPV6, ETH_P_IP);
0451     else
0452         return TC_ACT_OK;
0453 }
0454
0455 SEC("encap_ip6tnl_none")
0456 int __encap_ip6tnl_none(struct __sk_buff *skb)
0457 {
0458     if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
0459         return encap_ipv6(skb, IPPROTO_IPV6, ETH_P_IPV6);
0460     else
0461         return TC_ACT_OK;
0462 }
0463
0464 SEC("encap_ip6gre_none")
0465 int __encap_ip6gre_none(struct __sk_buff *skb)
0466 {
0467     if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
0468         return encap_ipv6(skb, IPPROTO_GRE, ETH_P_IPV6);
0469     else
0470         return TC_ACT_OK;
0471 }
0472
0473 SEC("encap_ip6gre_mpls")
0474 int __encap_ip6gre_mpls(struct __sk_buff *skb)
0475 {
0476     if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
0477         return encap_ipv6(skb, IPPROTO_GRE, ETH_P_MPLS_UC);
0478     else
0479         return TC_ACT_OK;
0480 }
0481
0482 SEC("encap_ip6gre_eth")
0483 int __encap_ip6gre_eth(struct __sk_buff *skb)
0484 {
0485     if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
0486         return encap_ipv6(skb, IPPROTO_GRE, ETH_P_TEB);
0487     else
0488         return TC_ACT_OK;
0489 }
0490
0491 SEC("encap_ip6udp_none")
0492 int __encap_ip6udp_none(struct __sk_buff *skb)
0493 {
0494     if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
0495         return encap_ipv6(skb, IPPROTO_UDP, ETH_P_IPV6);
0496     else
0497         return TC_ACT_OK;
0498 }
0499
0500 SEC("encap_ip6udp_mpls")
0501 int __encap_ip6udp_mpls(struct __sk_buff *skb)
0502 {
0503     if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
0504         return encap_ipv6(skb, IPPROTO_UDP, ETH_P_MPLS_UC);
0505     else
0506         return TC_ACT_OK;
0507 }
0508
0509 SEC("encap_ip6udp_eth")
0510 int __encap_ip6udp_eth(struct __sk_buff *skb)
0511 {
0512     if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
0513         return encap_ipv6(skb, IPPROTO_UDP, ETH_P_TEB);
0514     else
0515         return TC_ACT_OK;
0516 }
0517
0518 SEC("encap_ip6vxlan_eth")
0519 int __encap_ip6vxlan_eth(struct __sk_buff *skb)
0520 {
0521     if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
0522         return __encap_ipv6(skb, IPPROTO_UDP,
0523                     ETH_P_TEB,
0524                     EXTPROTO_VXLAN);
0525     else
0526         return TC_ACT_OK;
0527 }
0528
0529 static int decap_internal(struct __sk_buff *skb, int off, int len, char proto)
0530 {
0531     struct gre_hdr greh;
0532     struct udphdr udph;
0533     int olen = len;
0534
0535     switch (proto) {
0536     case IPPROTO_IPIP:
0537     case IPPROTO_IPV6:
0538         break;
0539     case IPPROTO_GRE:
0540         olen += sizeof(struct gre_hdr);
0541         if (bpf_skb_load_bytes(skb, off + len, &greh, sizeof(greh)) < 0)
0542             return TC_ACT_OK;
0543         switch (bpf_ntohs(greh.protocol)) {
0544         case ETH_P_MPLS_UC:
0545             olen += sizeof(mpls_label);
0546             break;
0547         case ETH_P_TEB:
0548             olen += ETH_HLEN;
0549             break;
0550         }
0551         break;
0552     case IPPROTO_UDP:
0553         olen += sizeof(struct udphdr);
0554         if (bpf_skb_load_bytes(skb, off + len, &udph, sizeof(udph)) < 0)
0555             return TC_ACT_OK;
0556         switch (bpf_ntohs(udph.dest)) {
0557         case MPLS_OVER_UDP_PORT:
0558             olen += sizeof(mpls_label);
0559             break;
0560         case ETH_OVER_UDP_PORT:
0561             olen += ETH_HLEN;
0562             break;
0563         case VXLAN_UDP_PORT:
0564             olen += ETH_HLEN + sizeof(struct vxlanhdr);
0565             break;
0566         }
0567         break;
0568     default:
0569         return TC_ACT_OK;
0570     }
0571
0572     if (bpf_skb_adjust_room(skb, -olen, BPF_ADJ_ROOM_MAC,
0573                 BPF_F_ADJ_ROOM_FIXED_GSO))
0574         return TC_ACT_SHOT;
0575
0576     return TC_ACT_OK;
0577 }
0578
0579 static int decap_ipv4(struct __sk_buff *skb)
0580 {
0581     struct iphdr iph_outer;
0582
0583     if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_outer,
0584                    sizeof(iph_outer)) < 0)
0585         return TC_ACT_OK;
0586
0587     if (iph_outer.ihl != 5)
0588         return TC_ACT_OK;
0589
0590     return decap_internal(skb, ETH_HLEN, sizeof(iph_outer),
0591                   iph_outer.protocol);
0592 }
0593
0594 static int decap_ipv6(struct __sk_buff *skb)
0595 {
0596     struct ipv6hdr iph_outer;
0597
0598     if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_outer,
0599                    sizeof(iph_outer)) < 0)
0600         return TC_ACT_OK;
0601
0602     return decap_internal(skb, ETH_HLEN, sizeof(iph_outer),
0603                   iph_outer.nexthdr);
0604 }
0605
0606 SEC("decap")
0607 int decap_f(struct __sk_buff *skb)
0608 {
0609     switch (skb->protocol) {
0610     case __bpf_constant_htons(ETH_P_IP):
0611         return decap_ipv4(skb);
0612     case __bpf_constant_htons(ETH_P_IPV6):
0613         return decap_ipv6(skb);
0614     default:
0615         /* does not match, ignore */
0616         return TC_ACT_OK;
0617     }
0618 }
0619
0620 char __license[] SEC("license") = "GPL";