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 #include <bpf_sockopt_helpers.h> 13 14 char _license[] SEC("license") = "GPL"; 15 16 struct svc_addr { 17 __be32 addr[4]; 18 __be16 port; 19 }; 20 21 struct { 22 __uint(type, BPF_MAP_TYPE_SK_STORAGE); 23 __uint(map_flags, BPF_F_NO_PREALLOC); 24 __type(key, int); 25 __type(value, struct svc_addr); 26 } service_mapping SEC(".maps"); 27 28 SEC("cgroup/connect6") 29 int connect6(struct bpf_sock_addr *ctx) 30 { 31 struct sockaddr_in6 sa = {}; 32 struct svc_addr *orig; 33 34 /* Force local address to [::1]:22223. */ 35 sa.sin6_family = AF_INET6; 36 sa.sin6_port = bpf_htons(22223); 37 sa.sin6_addr.s6_addr32[3] = bpf_htonl(1); 38 39 if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0) 40 return 0; 41 42 /* Rewire service [fc00::1]:60000 to backend [::1]:60124. */ 43 if (ctx->user_port == bpf_htons(60000)) { 44 orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0, 45 BPF_SK_STORAGE_GET_F_CREATE); 46 if (!orig) 47 return 0; 48 49 orig->addr[0] = ctx->user_ip6[0]; 50 orig->addr[1] = ctx->user_ip6[1]; 51 orig->addr[2] = ctx->user_ip6[2]; 52 orig->addr[3] = ctx->user_ip6[3]; 53 orig->port = ctx->user_port; 54 55 ctx->user_ip6[0] = 0; 56 ctx->user_ip6[1] = 0; 57 ctx->user_ip6[2] = 0; 58 ctx->user_ip6[3] = bpf_htonl(1); 59 ctx->user_port = bpf_htons(60124); 60 } 61 return 1; 62 } 63 64 SEC("cgroup/getsockname6") 65 int getsockname6(struct bpf_sock_addr *ctx) 66 { 67 if (!get_set_sk_priority(ctx)) 68 return 1; 69 70 /* Expose local server as [fc00::1]:60000 to client. */ 71 if (ctx->user_port == bpf_htons(60124)) { 72 ctx->user_ip6[0] = bpf_htonl(0xfc000000); 73 ctx->user_ip6[1] = 0; 74 ctx->user_ip6[2] = 0; 75 ctx->user_ip6[3] = bpf_htonl(1); 76 ctx->user_port = bpf_htons(60000); 77 } 78 return 1; 79 } 80 81 SEC("cgroup/getpeername6") 82 int getpeername6(struct bpf_sock_addr *ctx) 83 { 84 struct svc_addr *orig; 85 86 if (!get_set_sk_priority(ctx)) 87 return 1; 88 89 /* Expose service [fc00::1]:60000 as peer instead of backend. */ 90 if (ctx->user_port == bpf_htons(60124)) { 91 orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0, 0); 92 if (orig) { 93 ctx->user_ip6[0] = orig->addr[0]; 94 ctx->user_ip6[1] = orig->addr[1]; 95 ctx->user_ip6[2] = orig->addr[2]; 96 ctx->user_ip6[3] = orig->addr[3]; 97 ctx->user_port = orig->port; 98 } 99 } 100 return 1; 101 } 102