1 files changed, 90 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/connect_force_port4.c b/tools/testing/selftests/bpf/progs/connect_force_port4.c
new file mode 100644
index 000000000000..27a632dd382e
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/connect_force_port4.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <string.h>
+#include <stdbool.h>
+
+#include <linux/bpf.h>
+#include <linux/in.h>
+#include <linux/in6.h>
+#include <sys/socket.h>
+
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
+
+#include <bpf_sockopt_helpers.h>
+
+char _license[] SEC("license") = "GPL";
+
+struct svc_addr {
+	__be32 addr;
+	__be16 port;
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_SK_STORAGE);
+	__uint(map_flags, BPF_F_NO_PREALLOC);
+	__type(key, int);
+	__type(value, struct svc_addr);
+} service_mapping SEC(".maps");
+
+SEC("cgroup/connect4")
+int connect4(struct bpf_sock_addr *ctx)
+{
+	struct sockaddr_in sa = {};
+	struct svc_addr *orig;
+
+	/* Force local address to 127.0.0.1:22222. */
+	sa.sin_family = AF_INET;
+	sa.sin_port = bpf_htons(22222);
+	sa.sin_addr.s_addr = bpf_htonl(0x7f000001);
+
+	if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
+		return 0;
+
+	/* Rewire service 1.2.3.4:60000 to backend 127.0.0.1:60123. */
+	if (ctx->user_port == bpf_htons(60000)) {
+		orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0,
+					  BPF_SK_STORAGE_GET_F_CREATE);
+		if (!orig)
+			return 0;
+
+		orig->addr = ctx->user_ip4;
+		orig->port = ctx->user_port;
+
+		ctx->user_ip4 = bpf_htonl(0x7f000001);
+		ctx->user_port = bpf_htons(60123);
+	}
+	return 1;
+}
+
+SEC("cgroup/getsockname4")
+int getsockname4(struct bpf_sock_addr *ctx)
+{
+	if (!get_set_sk_priority(ctx))
+		return 1;
+
+	/* Expose local server as 1.2.3.4:60000 to client. */
+	if (ctx->user_port == bpf_htons(60123)) {
+		ctx->user_ip4 = bpf_htonl(0x01020304);
+		ctx->user_port = bpf_htons(60000);
+	}
+	return 1;
+}
+
+SEC("cgroup/getpeername4")
+int getpeername4(struct bpf_sock_addr *ctx)
+{
+	struct svc_addr *orig;
+
+	if (!get_set_sk_priority(ctx))
+		return 1;
+
+	/* Expose service 1.2.3.4:60000 as peer instead of backend. */
+	if (ctx->user_port == bpf_htons(60123)) {
+		orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0, 0);
+		if (orig) {
+			ctx->user_ip4 = orig->addr;
+			ctx->user_port = orig->port;
+		}
+	}
+	return 1;
+}