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 __u16 port = 0; 17 18 struct svc_addr { 19 __be32 addr[4]; 20 __be16 port; 21 }; 22 23 struct { 24 __uint(type, BPF_MAP_TYPE_SK_STORAGE); 25 __uint(map_flags, BPF_F_NO_PREALLOC); 26 __type(key, int); 27 __type(value, struct svc_addr); 28 } service_mapping SEC(".maps"); 29 30 SEC("cgroup/connect6") 31 int connect6(struct bpf_sock_addr *ctx) 32 { 33 struct sockaddr_in6 sa = {}; 34 struct svc_addr *orig; 35 36 /* Force local address to [::1]:22223. */ 37 sa.sin6_family = AF_INET6; 38 sa.sin6_port = bpf_htons(22223); 39 sa.sin6_addr.s6_addr32[3] = bpf_htonl(1); 40 41 if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0) 42 return 0; 43 44 /* Rewire service [fc00::1]:60000 to backend [::1]:port. */ 45 if (ctx->user_port == bpf_htons(60000)) { 46 orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0, 47 BPF_SK_STORAGE_GET_F_CREATE); 48 if (!orig) 49 return 0; 50 51 orig->addr[0] = ctx->user_ip6[0]; 52 orig->addr[1] = ctx->user_ip6[1]; 53 orig->addr[2] = ctx->user_ip6[2]; 54 orig->addr[3] = ctx->user_ip6[3]; 55 orig->port = ctx->user_port; 56 57 ctx->user_ip6[0] = 0; 58 ctx->user_ip6[1] = 0; 59 ctx->user_ip6[2] = 0; 60 ctx->user_ip6[3] = bpf_htonl(1); 61 ctx->user_port = bpf_htons(port); 62 } 63 return 1; 64 } 65 66 SEC("cgroup/getsockname6") 67 int getsockname6(struct bpf_sock_addr *ctx) 68 { 69 if (!get_set_sk_priority(ctx)) 70 return 1; 71 72 /* Expose local server as [fc00::1]:60000 to client. */ 73 if (ctx->user_port == bpf_htons(port)) { 74 ctx->user_ip6[0] = bpf_htonl(0xfc000000); 75 ctx->user_ip6[1] = 0; 76 ctx->user_ip6[2] = 0; 77 ctx->user_ip6[3] = bpf_htonl(1); 78 ctx->user_port = bpf_htons(60000); 79 } 80 return 1; 81 } 82 83 SEC("cgroup/getpeername6") 84 int getpeername6(struct bpf_sock_addr *ctx) 85 { 86 struct svc_addr *orig; 87 88 if (!get_set_sk_priority(ctx)) 89 return 1; 90 91 /* Expose service [fc00::1]:60000 as peer instead of backend. */ 92 if (ctx->user_port == bpf_htons(port)) { 93 orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0, 0); 94 if (orig) { 95 ctx->user_ip6[0] = orig->addr[0]; 96 ctx->user_ip6[1] = orig->addr[1]; 97 ctx->user_ip6[2] = orig->addr[2]; 98 ctx->user_ip6[3] = orig->addr[3]; 99 ctx->user_port = orig->port; 100 } 101 } 102 return 1; 103 } 104