SEC("cgroup/connect4")
int connect_v4_prog(struct bpf_sock_addr *ctx)
{
+ struct bpf_sock_tuple tuple = {};
struct sockaddr_in sa;
+ struct bpf_sock *sk;
+
+ /* Verify that new destination is available. */
+ memset(&tuple.ipv4.saddr, 0, sizeof(tuple.ipv4.saddr));
+ memset(&tuple.ipv4.sport, 0, sizeof(tuple.ipv4.sport));
+
+ tuple.ipv4.daddr = bpf_htonl(DST_REWRITE_IP4);
+ tuple.ipv4.dport = bpf_htons(DST_REWRITE_PORT4);
+
+ if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)
+ return 0;
+ else if (ctx->type == SOCK_STREAM)
+ sk = bpf_sk_lookup_tcp(ctx, &tuple, sizeof(tuple.ipv4), 0, 0);
+ else
+ sk = bpf_sk_lookup_udp(ctx, &tuple, sizeof(tuple.ipv4), 0, 0);
+
+ if (!sk)
+ return 0;
+
+ if (sk->src_ip4 != tuple.ipv4.daddr ||
+ sk->src_port != DST_REWRITE_PORT4) {
+ bpf_sk_release(sk);
+ return 0;
+ }
+
+ bpf_sk_release(sk);
/* Rewrite destination. */
ctx->user_ip4 = bpf_htonl(DST_REWRITE_IP4);
ctx->user_port = bpf_htons(DST_REWRITE_PORT4);
- if (ctx->type == SOCK_DGRAM || ctx->type == SOCK_STREAM) {
- ///* Rewrite source. */
- memset(&sa, 0, sizeof(sa));
+ /* Rewrite source. */
+ memset(&sa, 0, sizeof(sa));
- sa.sin_family = AF_INET;
- sa.sin_port = bpf_htons(0);
- sa.sin_addr.s_addr = bpf_htonl(SRC_REWRITE_IP4);
+ sa.sin_family = AF_INET;
+ sa.sin_port = bpf_htons(0);
+ sa.sin_addr.s_addr = bpf_htonl(SRC_REWRITE_IP4);
- if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
- return 0;
- }
+ if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
+ return 0;
return 1;
}
SEC("cgroup/connect6")
int connect_v6_prog(struct bpf_sock_addr *ctx)
{
+ struct bpf_sock_tuple tuple = {};
struct sockaddr_in6 sa;
+ struct bpf_sock *sk;
+
+ /* Verify that new destination is available. */
+ memset(&tuple.ipv6.saddr, 0, sizeof(tuple.ipv6.saddr));
+ memset(&tuple.ipv6.sport, 0, sizeof(tuple.ipv6.sport));
+
+ tuple.ipv6.daddr[0] = bpf_htonl(DST_REWRITE_IP6_0);
+ tuple.ipv6.daddr[1] = bpf_htonl(DST_REWRITE_IP6_1);
+ tuple.ipv6.daddr[2] = bpf_htonl(DST_REWRITE_IP6_2);
+ tuple.ipv6.daddr[3] = bpf_htonl(DST_REWRITE_IP6_3);
+
+ tuple.ipv6.dport = bpf_htons(DST_REWRITE_PORT6);
+
+ if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)
+ return 0;
+ else if (ctx->type == SOCK_STREAM)
+ sk = bpf_sk_lookup_tcp(ctx, &tuple, sizeof(tuple.ipv6), 0, 0);
+ else
+ sk = bpf_sk_lookup_udp(ctx, &tuple, sizeof(tuple.ipv6), 0, 0);
+
+ if (!sk)
+ return 0;
+
+ if (sk->src_ip6[0] != tuple.ipv6.daddr[0] ||
+ sk->src_ip6[1] != tuple.ipv6.daddr[1] ||
+ sk->src_ip6[2] != tuple.ipv6.daddr[2] ||
+ sk->src_ip6[3] != tuple.ipv6.daddr[3] ||
+ sk->src_port != DST_REWRITE_PORT6) {
+ bpf_sk_release(sk);
+ return 0;
+ }
+
+ bpf_sk_release(sk);
/* Rewrite destination. */
ctx->user_ip6[0] = bpf_htonl(DST_REWRITE_IP6_0);
ctx->user_port = bpf_htons(DST_REWRITE_PORT6);
- if (ctx->type == SOCK_DGRAM || ctx->type == SOCK_STREAM) {
- /* Rewrite source. */
- memset(&sa, 0, sizeof(sa));
+ /* Rewrite source. */
+ memset(&sa, 0, sizeof(sa));
- sa.sin6_family = AF_INET6;
- sa.sin6_port = bpf_htons(0);
+ sa.sin6_family = AF_INET6;
+ sa.sin6_port = bpf_htons(0);
- sa.sin6_addr.s6_addr32[0] = bpf_htonl(SRC_REWRITE_IP6_0);
- sa.sin6_addr.s6_addr32[1] = bpf_htonl(SRC_REWRITE_IP6_1);
- sa.sin6_addr.s6_addr32[2] = bpf_htonl(SRC_REWRITE_IP6_2);
- sa.sin6_addr.s6_addr32[3] = bpf_htonl(SRC_REWRITE_IP6_3);
+ sa.sin6_addr.s6_addr32[0] = bpf_htonl(SRC_REWRITE_IP6_0);
+ sa.sin6_addr.s6_addr32[1] = bpf_htonl(SRC_REWRITE_IP6_1);
+ sa.sin6_addr.s6_addr32[2] = bpf_htonl(SRC_REWRITE_IP6_2);
+ sa.sin6_addr.s6_addr32[3] = bpf_htonl(SRC_REWRITE_IP6_3);
- if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
- return 0;
- }
+ if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
+ return 0;
return 1;
}