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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 | // 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 UDP_PORT 5555 #define MPLS_OVER_UDP_PORT 6635 #define ETH_OVER_UDP_PORT 7777 /* 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 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[16]; /* enough space for L2 header */ } __attribute__((packed)); struct v6hdr { struct ipv6hdr ip; union l4hdr l4hdr; __u8 pad[16]; /* enough space for L2 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 udp_dst = UDP_PORT; struct iphdr iph_inner; struct v4hdr h_outer; struct tcphdr tcph; int olen, l2_len; 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; 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) */ switch (l2_proto) { case ETH_P_MPLS_UC: *((__u32 *)((__u8 *)&h_outer + olen)) = mpls_label; break; case ETH_P_TEB: if (bpf_skb_load_bytes(skb, 0, (__u8 *)&h_outer + olen, 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_ipv6(struct __sk_buff *skb, __u8 encap_proto, __u16 l2_proto) { __u16 udp_dst = UDP_PORT; struct ipv6hdr iph_inner; struct v6hdr h_outer; struct tcphdr tcph; int olen, l2_len; __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; 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); 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) */ switch (l2_proto) { case ETH_P_MPLS_UC: *((__u32 *)((__u8 *)&h_outer + olen)) = mpls_label; break; case ETH_P_TEB: if (bpf_skb_load_bytes(skb, 0, (__u8 *)&h_outer + olen, 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; } 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_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_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; } static int decap_internal(struct __sk_buff *skb, int off, int len, char proto) { char buf[sizeof(struct v6hdr)]; struct gre_hdr greh; struct udphdr udph; int olen = len; switch (proto) { case IPPROTO_IPIP: case IPPROTO_IPV6: 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; } 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"; |