1 // SPDX-License-Identifier: GPL-2.0 2 /* Copyright (c) 2022 Meta */ 3 #include <stddef.h> 4 #include <string.h> 5 #include <stdbool.h> 6 #include <linux/bpf.h> 7 #include <linux/if_ether.h> 8 #include <linux/if_packet.h> 9 #include <linux/ip.h> 10 #include <linux/ipv6.h> 11 #include <linux/in.h> 12 #include <linux/udp.h> 13 #include <linux/tcp.h> 14 #include <linux/pkt_cls.h> 15 #include <sys/socket.h> 16 #include <bpf/bpf_helpers.h> 17 #include <bpf/bpf_endian.h> 18 #include "test_iptunnel_common.h" 19 #include "bpf_kfuncs.h" 20 21 const size_t tcphdr_sz = sizeof(struct tcphdr); 22 const size_t udphdr_sz = sizeof(struct udphdr); 23 const size_t ethhdr_sz = sizeof(struct ethhdr); 24 const size_t iphdr_sz = sizeof(struct iphdr); 25 const size_t ipv6hdr_sz = sizeof(struct ipv6hdr); 26 27 struct { 28 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); 29 __uint(max_entries, 256); 30 __type(key, __u32); 31 __type(value, __u64); 32 } rxcnt SEC(".maps"); 33 34 struct { 35 __uint(type, BPF_MAP_TYPE_HASH); 36 __uint(max_entries, MAX_IPTNL_ENTRIES); 37 __type(key, struct vip); 38 __type(value, struct iptnl_info); 39 } vip2tnl SEC(".maps"); 40 41 static __always_inline void count_tx(__u32 protocol) 42 { 43 __u64 *rxcnt_count; 44 45 rxcnt_count = bpf_map_lookup_elem(&rxcnt, &protocol); 46 if (rxcnt_count) 47 *rxcnt_count += 1; 48 } 49 50 static __always_inline int get_dport(void *trans_data, __u8 protocol) 51 { 52 struct tcphdr *th; 53 struct udphdr *uh; 54 55 switch (protocol) { 56 case IPPROTO_TCP: 57 th = (struct tcphdr *)trans_data; 58 return th->dest; 59 case IPPROTO_UDP: 60 uh = (struct udphdr *)trans_data; 61 return uh->dest; 62 default: 63 return 0; 64 } 65 } 66 67 static __always_inline void set_ethhdr(struct ethhdr *new_eth, 68 const struct ethhdr *old_eth, 69 const struct iptnl_info *tnl, 70 __be16 h_proto) 71 { 72 memcpy(new_eth->h_source, old_eth->h_dest, sizeof(new_eth->h_source)); 73 memcpy(new_eth->h_dest, tnl->dmac, sizeof(new_eth->h_dest)); 74 new_eth->h_proto = h_proto; 75 } 76 77 static __always_inline int handle_ipv4(struct xdp_md *xdp, struct bpf_dynptr *xdp_ptr) 78 { 79 __u8 eth_buffer[ethhdr_sz + iphdr_sz + ethhdr_sz]; 80 __u8 iph_buffer_tcp[iphdr_sz + tcphdr_sz]; 81 __u8 iph_buffer_udp[iphdr_sz + udphdr_sz]; 82 struct bpf_dynptr new_xdp_ptr; 83 struct iptnl_info *tnl; 84 struct ethhdr *new_eth; 85 struct ethhdr *old_eth; 86 struct iphdr *iph; 87 __u16 *next_iph; 88 __u16 payload_len; 89 struct vip vip = {}; 90 int dport; 91 __u32 csum = 0; 92 int i; 93 94 __builtin_memset(eth_buffer, 0, sizeof(eth_buffer)); 95 __builtin_memset(iph_buffer_tcp, 0, sizeof(iph_buffer_tcp)); 96 __builtin_memset(iph_buffer_udp, 0, sizeof(iph_buffer_udp)); 97 98 if (ethhdr_sz + iphdr_sz + tcphdr_sz > xdp->data_end - xdp->data) 99 iph = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, iph_buffer_udp, sizeof(iph_buffer_udp)); 100 else 101 iph = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, iph_buffer_tcp, sizeof(iph_buffer_tcp)); 102 103 if (!iph) 104 return XDP_DROP; 105 106 dport = get_dport(iph + 1, iph->protocol); 107 if (dport == -1) 108 return XDP_DROP; 109 110 vip.protocol = iph->protocol; 111 vip.family = AF_INET; 112 vip.daddr.v4 = iph->daddr; 113 vip.dport = dport; 114 payload_len = bpf_ntohs(iph->tot_len); 115 116 tnl = bpf_map_lookup_elem(&vip2tnl, &vip); 117 /* It only does v4-in-v4 */ 118 if (!tnl || tnl->family != AF_INET) 119 return XDP_PASS; 120 121 if (bpf_xdp_adjust_head(xdp, 0 - (int)iphdr_sz)) 122 return XDP_DROP; 123 124 bpf_dynptr_from_xdp(xdp, 0, &new_xdp_ptr); 125 new_eth = bpf_dynptr_slice_rdwr(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer)); 126 if (!new_eth) 127 return XDP_DROP; 128 129 iph = (struct iphdr *)(new_eth + 1); 130 old_eth = (struct ethhdr *)(iph + 1); 131 132 set_ethhdr(new_eth, old_eth, tnl, bpf_htons(ETH_P_IP)); 133 134 if (new_eth == eth_buffer) 135 bpf_dynptr_write(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer), 0); 136 137 iph->version = 4; 138 iph->ihl = iphdr_sz >> 2; 139 iph->frag_off = 0; 140 iph->protocol = IPPROTO_IPIP; 141 iph->check = 0; 142 iph->tos = 0; 143 iph->tot_len = bpf_htons(payload_len + iphdr_sz); 144 iph->daddr = tnl->daddr.v4; 145 iph->saddr = tnl->saddr.v4; 146 iph->ttl = 8; 147 148 next_iph = (__u16 *)iph; 149 for (i = 0; i < iphdr_sz >> 1; i++) 150 csum += *next_iph++; 151 152 iph->check = ~((csum & 0xffff) + (csum >> 16)); 153 154 count_tx(vip.protocol); 155 156 return XDP_TX; 157 } 158 159 static __always_inline int handle_ipv6(struct xdp_md *xdp, struct bpf_dynptr *xdp_ptr) 160 { 161 __u8 eth_buffer[ethhdr_sz + ipv6hdr_sz + ethhdr_sz]; 162 __u8 ip6h_buffer_tcp[ipv6hdr_sz + tcphdr_sz]; 163 __u8 ip6h_buffer_udp[ipv6hdr_sz + udphdr_sz]; 164 struct bpf_dynptr new_xdp_ptr; 165 struct iptnl_info *tnl; 166 struct ethhdr *new_eth; 167 struct ethhdr *old_eth; 168 struct ipv6hdr *ip6h; 169 __u16 payload_len; 170 struct vip vip = {}; 171 int dport; 172 173 __builtin_memset(eth_buffer, 0, sizeof(eth_buffer)); 174 __builtin_memset(ip6h_buffer_tcp, 0, sizeof(ip6h_buffer_tcp)); 175 __builtin_memset(ip6h_buffer_udp, 0, sizeof(ip6h_buffer_udp)); 176 177 if (ethhdr_sz + iphdr_sz + tcphdr_sz > xdp->data_end - xdp->data) 178 ip6h = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, ip6h_buffer_udp, sizeof(ip6h_buffer_udp)); 179 else 180 ip6h = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, ip6h_buffer_tcp, sizeof(ip6h_buffer_tcp)); 181 182 if (!ip6h) 183 return XDP_DROP; 184 185 dport = get_dport(ip6h + 1, ip6h->nexthdr); 186 if (dport == -1) 187 return XDP_DROP; 188 189 vip.protocol = ip6h->nexthdr; 190 vip.family = AF_INET6; 191 memcpy(vip.daddr.v6, ip6h->daddr.s6_addr32, sizeof(vip.daddr)); 192 vip.dport = dport; 193 payload_len = ip6h->payload_len; 194 195 tnl = bpf_map_lookup_elem(&vip2tnl, &vip); 196 /* It only does v6-in-v6 */ 197 if (!tnl || tnl->family != AF_INET6) 198 return XDP_PASS; 199 200 if (bpf_xdp_adjust_head(xdp, 0 - (int)ipv6hdr_sz)) 201 return XDP_DROP; 202 203 bpf_dynptr_from_xdp(xdp, 0, &new_xdp_ptr); 204 new_eth = bpf_dynptr_slice_rdwr(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer)); 205 if (!new_eth) 206 return XDP_DROP; 207 208 ip6h = (struct ipv6hdr *)(new_eth + 1); 209 old_eth = (struct ethhdr *)(ip6h + 1); 210 211 set_ethhdr(new_eth, old_eth, tnl, bpf_htons(ETH_P_IPV6)); 212 213 if (new_eth == eth_buffer) 214 bpf_dynptr_write(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer), 0); 215 216 ip6h->version = 6; 217 ip6h->priority = 0; 218 memset(ip6h->flow_lbl, 0, sizeof(ip6h->flow_lbl)); 219 ip6h->payload_len = bpf_htons(bpf_ntohs(payload_len) + ipv6hdr_sz); 220 ip6h->nexthdr = IPPROTO_IPV6; 221 ip6h->hop_limit = 8; 222 memcpy(ip6h->saddr.s6_addr32, tnl->saddr.v6, sizeof(tnl->saddr.v6)); 223 memcpy(ip6h->daddr.s6_addr32, tnl->daddr.v6, sizeof(tnl->daddr.v6)); 224 225 count_tx(vip.protocol); 226 227 return XDP_TX; 228 } 229 230 SEC("xdp") 231 int _xdp_tx_iptunnel(struct xdp_md *xdp) 232 { 233 __u8 buffer[ethhdr_sz]; 234 struct bpf_dynptr ptr; 235 struct ethhdr *eth; 236 __u16 h_proto; 237 238 __builtin_memset(buffer, 0, sizeof(buffer)); 239 240 bpf_dynptr_from_xdp(xdp, 0, &ptr); 241 eth = bpf_dynptr_slice(&ptr, 0, buffer, sizeof(buffer)); 242 if (!eth) 243 return XDP_DROP; 244 245 h_proto = eth->h_proto; 246 247 if (h_proto == bpf_htons(ETH_P_IP)) 248 return handle_ipv4(xdp, &ptr); 249 else if (h_proto == bpf_htons(ETH_P_IPV6)) 250 251 return handle_ipv6(xdp, &ptr); 252 else 253 return XDP_DROP; 254 } 255 256 char _license[] SEC("license") = "GPL"; 257