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 int _version SEC("version") = 1; 16 17 struct svc_addr { 18 __be32 addr[4]; 19 __be16 port; 20 }; 21 22 struct { 23 __uint(type, BPF_MAP_TYPE_SK_STORAGE); 24 __uint(map_flags, BPF_F_NO_PREALLOC); 25 __type(key, int); 26 __type(value, struct svc_addr); 27 } service_mapping SEC(".maps"); 28 29 SEC("cgroup/connect6") 30 int connect6(struct bpf_sock_addr *ctx) 31 { 32 struct sockaddr_in6 sa = {}; 33 struct svc_addr *orig; 34 35 /* Force local address to [::1]:22223. */ 36 sa.sin6_family = AF_INET6; 37 sa.sin6_port = bpf_htons(22223); 38 sa.sin6_addr.s6_addr32[3] = bpf_htonl(1); 39 40 if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0) 41 return 0; 42 43 /* Rewire service [fc00::1]:60000 to backend [::1]:60124. */ 44 if (ctx->user_port == bpf_htons(60000)) { 45 orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0, 46 BPF_SK_STORAGE_GET_F_CREATE); 47 if (!orig) 48 return 0; 49 50 orig->addr[0] = ctx->user_ip6[0]; 51 orig->addr[1] = ctx->user_ip6[1]; 52 orig->addr[2] = ctx->user_ip6[2]; 53 orig->addr[3] = ctx->user_ip6[3]; 54 orig->port = ctx->user_port; 55 56 ctx->user_ip6[0] = 0; 57 ctx->user_ip6[1] = 0; 58 ctx->user_ip6[2] = 0; 59 ctx->user_ip6[3] = bpf_htonl(1); 60 ctx->user_port = bpf_htons(60124); 61 } 62 return 1; 63 } 64 65 SEC("cgroup/getsockname6") 66 int getsockname6(struct bpf_sock_addr *ctx) 67 { 68 if (!get_set_sk_priority(ctx)) 69 return 1; 70 71 /* Expose local server as [fc00::1]:60000 to client. */ 72 if (ctx->user_port == bpf_htons(60124)) { 73 ctx->user_ip6[0] = bpf_htonl(0xfc000000); 74 ctx->user_ip6[1] = 0; 75 ctx->user_ip6[2] = 0; 76 ctx->user_ip6[3] = bpf_htonl(1); 77 ctx->user_port = bpf_htons(60000); 78 } 79 return 1; 80 } 81 82 SEC("cgroup/getpeername6") 83 int getpeername6(struct bpf_sock_addr *ctx) 84 { 85 struct svc_addr *orig; 86 87 if (!get_set_sk_priority(ctx)) 88 return 1; 89 90 /* Expose service [fc00::1]:60000 as peer instead of backend. */ 91 if (ctx->user_port == bpf_htons(60124)) { 92 orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0, 0); 93 if (orig) { 94 ctx->user_ip6[0] = orig->addr[0]; 95 ctx->user_ip6[1] = orig->addr[1]; 96 ctx->user_ip6[2] = orig->addr[2]; 97 ctx->user_ip6[3] = orig->addr[3]; 98 ctx->user_port = orig->port; 99 } 100 } 101 return 1; 102 } 103