tools/testing/selftests/bpf/progs/connect4_prog.c

   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_IP4         0x7f000004U
  16 #define DST_REWRITE_IP4         0x7f000001U
  17 #define DST_REWRITE_PORT4       4444
  18
  19 int _version SEC("version") = 1;
  20
  21 __attribute__ ((noinline))
  22 int do_bind(struct bpf_sock_addr *ctx)
  23 {
  24         struct sockaddr_in sa = {};
  25
  26         sa.sin_family = AF_INET;
  27         sa.sin_port = bpf_htons(0);
  28         sa.sin_addr.s_addr = bpf_htonl(SRC_REWRITE_IP4);
  29
  30         if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
  31                 return 0;
  32
  33         return 1;
  34 }
  35
  36 SEC("cgroup/connect4")
  37 int connect_v4_prog(struct bpf_sock_addr *ctx)
  38 {
  39         struct bpf_sock_tuple tuple = {};
  40         struct bpf_sock *sk;
  41
  42         /* Verify that new destination is available. */
  43         memset(&tuple.ipv4.saddr, 0, sizeof(tuple.ipv4.saddr));
  44         memset(&tuple.ipv4.sport, 0, sizeof(tuple.ipv4.sport));
  45
  46         tuple.ipv4.daddr = bpf_htonl(DST_REWRITE_IP4);
  47         tuple.ipv4.dport = bpf_htons(DST_REWRITE_PORT4);
  48
  49         if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)
  50                 return 0;
  51         else if (ctx->type == SOCK_STREAM)
  52                 sk = bpf_sk_lookup_tcp(ctx, &tuple, sizeof(tuple.ipv4),
  53                                        BPF_F_CURRENT_NETNS, 0);
  54         else
  55                 sk = bpf_sk_lookup_udp(ctx, &tuple, sizeof(tuple.ipv4),
  56                                        BPF_F_CURRENT_NETNS, 0);
  57
  58         if (!sk)
  59                 return 0;
  60
  61         if (sk->src_ip4 != tuple.ipv4.daddr ||
  62             sk->src_port != DST_REWRITE_PORT4) {
  63                 bpf_sk_release(sk);
  64                 return 0;
  65         }
  66
  67         bpf_sk_release(sk);
  68
  69         /* Rewrite destination. */
  70         ctx->user_ip4 = bpf_htonl(DST_REWRITE_IP4);
  71         ctx->user_port = bpf_htons(DST_REWRITE_PORT4);
  72
  73         return do_bind(ctx) ? 1 : 0;
  74 }
  75
  76 char _license[] SEC("license") = "GPL";