tools/testing/selftests/bpf/progs/sendmsg6_prog.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (c) 2018 Facebook
   3
   4 #include <linux/stddef.h>
   5 #include <linux/bpf.h>
   6 #include <sys/socket.h>
   7
   8 #include "bpf_helpers.h"
   9 #include "bpf_endian.h"
  10
  11 #define SRC_REWRITE_IP6_0       0
  12 #define SRC_REWRITE_IP6_1       0
  13 #define SRC_REWRITE_IP6_2       0
  14 #define SRC_REWRITE_IP6_3       6
  15
  16 #define DST_REWRITE_IP6_0       0
  17 #define DST_REWRITE_IP6_1       0
  18 #define DST_REWRITE_IP6_2       0
  19 #define DST_REWRITE_IP6_3       1
  20
  21 #define DST_REWRITE_PORT6       6666
  22
  23 int _version SEC("version") = 1;
  24
  25 SEC("cgroup/sendmsg6")
  26 int sendmsg_v6_prog(struct bpf_sock_addr *ctx)
  27 {
  28         if (ctx->type != SOCK_DGRAM)
  29                 return 0;
  30
  31         /* Rewrite source. */
  32         if (ctx->msg_src_ip6[3] == bpf_htonl(1) ||
  33             ctx->msg_src_ip6[3] == bpf_htonl(0)) {
  34                 ctx->msg_src_ip6[0] = bpf_htonl(SRC_REWRITE_IP6_0);
  35                 ctx->msg_src_ip6[1] = bpf_htonl(SRC_REWRITE_IP6_1);
  36                 ctx->msg_src_ip6[2] = bpf_htonl(SRC_REWRITE_IP6_2);
  37                 ctx->msg_src_ip6[3] = bpf_htonl(SRC_REWRITE_IP6_3);
  38         } else {
  39                 /* Unexpected source. Reject sendmsg. */
  40                 return 0;
  41         }
  42
  43         /* Rewrite destination. */
  44         if ((ctx->user_ip6[0] & 0xFFFF) == bpf_htons(0xFACE) &&
  45              ctx->user_ip6[0] >> 16 == bpf_htons(0xB00C)) {
  46                 ctx->user_ip6[0] = bpf_htonl(DST_REWRITE_IP6_0);
  47                 ctx->user_ip6[1] = bpf_htonl(DST_REWRITE_IP6_1);
  48                 ctx->user_ip6[2] = bpf_htonl(DST_REWRITE_IP6_2);
  49                 ctx->user_ip6[3] = bpf_htonl(DST_REWRITE_IP6_3);
  50
  51                 ctx->user_port = bpf_htons(DST_REWRITE_PORT6);
  52         } else {
  53                 /* Unexpected destination. Reject sendmsg. */
  54                 return 0;
  55         }
  56
  57         return 1;
  58 }
  59
  60 char _license[] SEC("license") = "GPL";