text: // SPDX-License-Identifier: GPL-2.0
  // Copyright (c) 2018 Facebook
  
  #include "vmlinux.h"
  
  #include <bpf/bpf_helpers.h>
  #include <bpf/bpf_endian.h>
  #include <bpf/bpf_tracing.h>
  
  #define AF_INET6 10
  
  struct socket_cookie {
  	__u64 cookie_key;
  	__u32 cookie_value;
  };
  
  struct {
  	__uint(type, BPF_MAP_TYPE_SK_STORAGE);
  	__uint(map_flags, BPF_F_NO_PREALLOC);
  	__type(key, int);
  	__type(value, struct socket_cookie);
  } socket_cookies SEC(".maps");
  
  /*
   * These three programs get executed in a row on connect() syscalls. The
   * userspace side of the test creates a client socket, issues a connect() on it
   * and then checks that the local storage associated with this socket has:
   * cookie_value == local_port << 8 | 0xFF
   * The different parts of this cookie_value are appended by those hooks if they
   * all agree on the output of bpf_get_socket_cookie().
   */
  SEC("cgroup/connect6")
  int set_cookie(struct bpf_sock_addr *ctx)
  {
  	struct socket_cookie *p;
  
  	if (ctx->family != AF_INET6 || ctx->user_family != AF_INET6)
  		return 1;
  
  	p = bpf_sk_storage_get(&socket_cookies, ctx->sk, 0,
  			       BPF_SK_STORAGE_GET_F_CREATE);
  	if (!p)
  		return 1;
  
  	p->cookie_value = 0xF;
  	p->cookie_key = bpf_get_socket_cookie(ctx);
  
  	return 1;
  }
  
  SEC("sockops")
  int update_cookie_sockops(struct bpf_sock_ops *ctx)
  {
  	struct bpf_sock *sk = ctx->sk;
  	struct socket_cookie *p;
  
  	if (ctx->family != AF_INET6)
  		return 1;
  
  	if (ctx->op != BPF_SOCK_OPS_TCP_CONNECT_CB)
  		return 1;
  
  	if (!sk)
  		return 1;
  
  	p = bpf_sk_storage_get(&socket_cookies, sk, 0, 0);
  	if (!p)
  		return 1;
  
  	if (p->cookie_key != bpf_get_socket_cookie(ctx))
  		return 1;
  
  	p->cookie_value |= (ctx->local_port << 8);
  
  	return 1;
  }
  
  SEC("fexit/inet_stream_connect")
  int BPF_PROG(update_cookie_tracing, struct socket *sock,
  	     struct sockaddr *uaddr, int addr_len, int flags)
  {
  	struct socket_cookie *p;
  
  	if (uaddr->sa_family != AF_INET6)
  		return 0;
  
  	p = bpf_sk_storage_get(&socket_cookies, sock->sk, 0, 0);
  	if (!p)
  		return 0;
  
  	if (p->cookie_key != bpf_get_socket_cookie(sock->sk))
  		return 0;
  
  	p->cookie_value |= 0xF0;
  
  	return 0;
  }
  
  char _license[] SEC("license") = "GPL";
  