1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (c) 2018 Facebook 3 4 #include <string.h> 5 6 #include <linux/stddef.h> 7 #include <linux/bpf.h> 8 #include <linux/in.h> 9 #include <linux/in6.h> 10 #include <sys/socket.h> 11 12 #include <bpf/bpf_helpers.h> 13 #include <bpf/bpf_endian.h> 14 15 #define SRC_REWRITE_IP6_0 0 16 #define SRC_REWRITE_IP6_1 0 17 #define SRC_REWRITE_IP6_2 0 18 #define SRC_REWRITE_IP6_3 6 19 20 #define DST_REWRITE_IP6_0 0 21 #define DST_REWRITE_IP6_1 0 22 #define DST_REWRITE_IP6_2 0 23 #define DST_REWRITE_IP6_3 1 24 25 #define DST_REWRITE_PORT6 6666 26 27 int _version SEC("version") = 1; 28 29 SEC("cgroup/connect6") 30 int connect_v6_prog(struct bpf_sock_addr *ctx) 31 { 32 struct bpf_sock_tuple tuple = {}; 33 struct sockaddr_in6 sa; 34 struct bpf_sock *sk; 35 36 /* Verify that new destination is available. */ 37 memset(&tuple.ipv6.saddr, 0, sizeof(tuple.ipv6.saddr)); 38 memset(&tuple.ipv6.sport, 0, sizeof(tuple.ipv6.sport)); 39 40 tuple.ipv6.daddr[0] = bpf_htonl(DST_REWRITE_IP6_0); 41 tuple.ipv6.daddr[1] = bpf_htonl(DST_REWRITE_IP6_1); 42 tuple.ipv6.daddr[2] = bpf_htonl(DST_REWRITE_IP6_2); 43 tuple.ipv6.daddr[3] = bpf_htonl(DST_REWRITE_IP6_3); 44 45 tuple.ipv6.dport = bpf_htons(DST_REWRITE_PORT6); 46 47 if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM) 48 return 0; 49 else if (ctx->type == SOCK_STREAM) 50 sk = bpf_sk_lookup_tcp(ctx, &tuple, sizeof(tuple.ipv6), 51 BPF_F_CURRENT_NETNS, 0); 52 else 53 sk = bpf_sk_lookup_udp(ctx, &tuple, sizeof(tuple.ipv6), 54 BPF_F_CURRENT_NETNS, 0); 55 56 if (!sk) 57 return 0; 58 59 if (sk->src_ip6[0] != tuple.ipv6.daddr[0] || 60 sk->src_ip6[1] != tuple.ipv6.daddr[1] || 61 sk->src_ip6[2] != tuple.ipv6.daddr[2] || 62 sk->src_ip6[3] != tuple.ipv6.daddr[3] || 63 sk->src_port != DST_REWRITE_PORT6) { 64 bpf_sk_release(sk); 65 return 0; 66 } 67 68 bpf_sk_release(sk); 69 70 /* Rewrite destination. */ 71 ctx->user_ip6[0] = bpf_htonl(DST_REWRITE_IP6_0); 72 ctx->user_ip6[1] = bpf_htonl(DST_REWRITE_IP6_1); 73 ctx->user_ip6[2] = bpf_htonl(DST_REWRITE_IP6_2); 74 ctx->user_ip6[3] = bpf_htonl(DST_REWRITE_IP6_3); 75 76 ctx->user_port = bpf_htons(DST_REWRITE_PORT6); 77 78 /* Rewrite source. */ 79 memset(&sa, 0, sizeof(sa)); 80 81 sa.sin6_family = AF_INET6; 82 sa.sin6_port = bpf_htons(0); 83 84 sa.sin6_addr.s6_addr32[0] = bpf_htonl(SRC_REWRITE_IP6_0); 85 sa.sin6_addr.s6_addr32[1] = bpf_htonl(SRC_REWRITE_IP6_1); 86 sa.sin6_addr.s6_addr32[2] = bpf_htonl(SRC_REWRITE_IP6_2); 87 sa.sin6_addr.s6_addr32[3] = bpf_htonl(SRC_REWRITE_IP6_3); 88 89 if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0) 90 return 0; 91 92 return 1; 93 } 94 95 char _license[] SEC("license") = "GPL"; 96