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 SEC("cgroup/connect6") 28 int connect_v6_prog(struct bpf_sock_addr *ctx) 29 { 30 struct bpf_sock_tuple tuple = {}; 31 struct sockaddr_in6 sa; 32 struct bpf_sock *sk; 33 34 /* Verify that new destination is available. */ 35 memset(&tuple.ipv6.saddr, 0, sizeof(tuple.ipv6.saddr)); 36 memset(&tuple.ipv6.sport, 0, sizeof(tuple.ipv6.sport)); 37 38 tuple.ipv6.daddr[0] = bpf_htonl(DST_REWRITE_IP6_0); 39 tuple.ipv6.daddr[1] = bpf_htonl(DST_REWRITE_IP6_1); 40 tuple.ipv6.daddr[2] = bpf_htonl(DST_REWRITE_IP6_2); 41 tuple.ipv6.daddr[3] = bpf_htonl(DST_REWRITE_IP6_3); 42 43 tuple.ipv6.dport = bpf_htons(DST_REWRITE_PORT6); 44 45 if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM) 46 return 0; 47 else if (ctx->type == SOCK_STREAM) 48 sk = bpf_sk_lookup_tcp(ctx, &tuple, sizeof(tuple.ipv6), 49 BPF_F_CURRENT_NETNS, 0); 50 else 51 sk = bpf_sk_lookup_udp(ctx, &tuple, sizeof(tuple.ipv6), 52 BPF_F_CURRENT_NETNS, 0); 53 54 if (!sk) 55 return 0; 56 57 if (sk->src_ip6[0] != tuple.ipv6.daddr[0] || 58 sk->src_ip6[1] != tuple.ipv6.daddr[1] || 59 sk->src_ip6[2] != tuple.ipv6.daddr[2] || 60 sk->src_ip6[3] != tuple.ipv6.daddr[3] || 61 sk->src_port != DST_REWRITE_PORT6) { 62 bpf_sk_release(sk); 63 return 0; 64 } 65 66 bpf_sk_release(sk); 67 68 /* Rewrite destination. */ 69 ctx->user_ip6[0] = bpf_htonl(DST_REWRITE_IP6_0); 70 ctx->user_ip6[1] = bpf_htonl(DST_REWRITE_IP6_1); 71 ctx->user_ip6[2] = bpf_htonl(DST_REWRITE_IP6_2); 72 ctx->user_ip6[3] = bpf_htonl(DST_REWRITE_IP6_3); 73 74 ctx->user_port = bpf_htons(DST_REWRITE_PORT6); 75 76 /* Rewrite source. */ 77 memset(&sa, 0, sizeof(sa)); 78 79 sa.sin6_family = AF_INET6; 80 sa.sin6_port = bpf_htons(0); 81 82 sa.sin6_addr.s6_addr32[0] = bpf_htonl(SRC_REWRITE_IP6_0); 83 sa.sin6_addr.s6_addr32[1] = bpf_htonl(SRC_REWRITE_IP6_1); 84 sa.sin6_addr.s6_addr32[2] = bpf_htonl(SRC_REWRITE_IP6_2); 85 sa.sin6_addr.s6_addr32[3] = bpf_htonl(SRC_REWRITE_IP6_3); 86 87 if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0) 88 return 0; 89 90 return 1; 91 } 92 93 char _license[] SEC("license") = "GPL"; 94