tools/testing/selftests/bpf/prog_tests/flow_dissector_load_bytes.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <test_progs.h>
   3 #include <network_helpers.h>
   4
   5 void serial_test_flow_dissector_load_bytes(void)
   6 {
   7         struct bpf_flow_keys flow_keys;
   8         struct bpf_insn prog[] = {
   9                 // BPF_REG_1 - 1st argument: context
  10                 // BPF_REG_2 - 2nd argument: offset, start at first byte
  11                 BPF_MOV64_IMM(BPF_REG_2, 0),
  12                 // BPF_REG_3 - 3rd argument: destination, reserve byte on stack
  13                 BPF_ALU64_REG(BPF_MOV, BPF_REG_3, BPF_REG_10),
  14                 BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, -1),
  15                 // BPF_REG_4 - 4th argument: copy one byte
  16                 BPF_MOV64_IMM(BPF_REG_4, 1),
  17                 // bpf_skb_load_bytes(ctx, sizeof(pkt_v4), ptr, 1)
  18                 BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
  19                              BPF_FUNC_skb_load_bytes),
  20                 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 2),
  21                 // if (ret == 0) return BPF_DROP (2)
  22                 BPF_MOV64_IMM(BPF_REG_0, BPF_DROP),
  23                 BPF_EXIT_INSN(),
  24                 // if (ret != 0) return BPF_OK (0)
  25                 BPF_MOV64_IMM(BPF_REG_0, BPF_OK),
  26                 BPF_EXIT_INSN(),
  27         };
  28         int fd, err;
  29         LIBBPF_OPTS(bpf_test_run_opts, topts,
  30                 .data_in = &pkt_v4,
  31                 .data_size_in = sizeof(pkt_v4),
  32                 .data_out = &flow_keys,
  33                 .data_size_out = sizeof(flow_keys),
  34                 .repeat = 1,
  35         );
  36
  37         /* make sure bpf_skb_load_bytes is not allowed from skb-less context
  38          */
  39         fd = bpf_test_load_program(BPF_PROG_TYPE_FLOW_DISSECTOR, prog,
  40                               ARRAY_SIZE(prog), "GPL", 0, NULL, 0);
  41         ASSERT_GE(fd, 0, "bpf_test_load_program good fd");
  42
  43         err = bpf_prog_test_run_opts(fd, &topts);
  44         ASSERT_OK(err, "test_run");
  45         ASSERT_EQ(topts.data_size_out, sizeof(flow_keys),
  46                   "test_run data_size_out");
  47         ASSERT_EQ(topts.retval, BPF_OK, "test_run retval");
  48
  49         if (fd >= -1)
  50                 close(fd);
  51 }