1 // SPDX-License-Identifier: GPL-2.0 2 #include <string.h> 3 4 #include <linux/bpf.h> 5 #include <linux/in.h> 6 #include <linux/in6.h> 7 #include <sys/socket.h> 8 9 #include <bpf/bpf_helpers.h> 10 #include <bpf/bpf_endian.h> 11 12 char _license[] SEC("license") = "GPL"; 13 int _version SEC("version") = 1; 14 15 struct svc_addr { 16 __be32 addr[4]; 17 __be16 port; 18 }; 19 20 struct { 21 __uint(type, BPF_MAP_TYPE_SK_STORAGE); 22 __uint(map_flags, BPF_F_NO_PREALLOC); 23 __type(key, int); 24 __type(value, struct svc_addr); 25 } service_mapping SEC(".maps"); 26 27 SEC("cgroup/connect6") 28 int connect6(struct bpf_sock_addr *ctx) 29 { 30 struct sockaddr_in6 sa = {}; 31 struct svc_addr *orig; 32 33 /* Force local address to [::1]:22223. */ 34 sa.sin6_family = AF_INET6; 35 sa.sin6_port = bpf_htons(22223); 36 sa.sin6_addr.s6_addr32[3] = bpf_htonl(1); 37 38 if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0) 39 return 0; 40 41 /* Rewire service [fc00::1]:60000 to backend [::1]:60124. */ 42 if (ctx->user_port == bpf_htons(60000)) { 43 orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0, 44 BPF_SK_STORAGE_GET_F_CREATE); 45 if (!orig) 46 return 0; 47 48 orig->addr[0] = ctx->user_ip6[0]; 49 orig->addr[1] = ctx->user_ip6[1]; 50 orig->addr[2] = ctx->user_ip6[2]; 51 orig->addr[3] = ctx->user_ip6[3]; 52 orig->port = ctx->user_port; 53 54 ctx->user_ip6[0] = 0; 55 ctx->user_ip6[1] = 0; 56 ctx->user_ip6[2] = 0; 57 ctx->user_ip6[3] = bpf_htonl(1); 58 ctx->user_port = bpf_htons(60124); 59 } 60 return 1; 61 } 62 63 SEC("cgroup/getsockname6") 64 int getsockname6(struct bpf_sock_addr *ctx) 65 { 66 /* Expose local server as [fc00::1]:60000 to client. */ 67 if (ctx->user_port == bpf_htons(60124)) { 68 ctx->user_ip6[0] = bpf_htonl(0xfc000000); 69 ctx->user_ip6[1] = 0; 70 ctx->user_ip6[2] = 0; 71 ctx->user_ip6[3] = bpf_htonl(1); 72 ctx->user_port = bpf_htons(60000); 73 } 74 return 1; 75 } 76 77 SEC("cgroup/getpeername6") 78 int getpeername6(struct bpf_sock_addr *ctx) 79 { 80 struct svc_addr *orig; 81 82 /* Expose service [fc00::1]:60000 as peer instead of backend. */ 83 if (ctx->user_port == bpf_htons(60124)) { 84 orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0, 0); 85 if (orig) { 86 ctx->user_ip6[0] = orig->addr[0]; 87 ctx->user_ip6[1] = orig->addr[1]; 88 ctx->user_ip6[2] = orig->addr[2]; 89 ctx->user_ip6[3] = orig->addr[3]; 90 ctx->user_port = orig->port; 91 } 92 } 93 return 1; 94 } 95