bpf/prog_tests/flow_dissector_load_bytes.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 #include <test_progs.h>
0003 #include <network_helpers.h>
0004
0005 void serial_test_flow_dissector_load_bytes(void)
0006 {
0007     struct bpf_flow_keys flow_keys;
0008     struct bpf_insn prog[] = {
0009         // BPF_REG_1 - 1st argument: context
0010         // BPF_REG_2 - 2nd argument: offset, start at first byte
0011         BPF_MOV64_IMM(BPF_REG_2, 0),
0012         // BPF_REG_3 - 3rd argument: destination, reserve byte on stack
0013         BPF_ALU64_REG(BPF_MOV, BPF_REG_3, BPF_REG_10),
0014         BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, -1),
0015         // BPF_REG_4 - 4th argument: copy one byte
0016         BPF_MOV64_IMM(BPF_REG_4, 1),
0017         // bpf_skb_load_bytes(ctx, sizeof(pkt_v4), ptr, 1)
0018         BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
0019                  BPF_FUNC_skb_load_bytes),
0020         BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 2),
0021         // if (ret == 0) return BPF_DROP (2)
0022         BPF_MOV64_IMM(BPF_REG_0, BPF_DROP),
0023         BPF_EXIT_INSN(),
0024         // if (ret != 0) return BPF_OK (0)
0025         BPF_MOV64_IMM(BPF_REG_0, BPF_OK),
0026         BPF_EXIT_INSN(),
0027     };
0028     int fd, err;
0029     LIBBPF_OPTS(bpf_test_run_opts, topts,
0030         .data_in = &pkt_v4,
0031         .data_size_in = sizeof(pkt_v4),
0032         .data_out = &flow_keys,
0033         .data_size_out = sizeof(flow_keys),
0034         .repeat = 1,
0035     );
0036
0037     /* make sure bpf_skb_load_bytes is not allowed from skb-less context
0038      */
0039     fd = bpf_test_load_program(BPF_PROG_TYPE_FLOW_DISSECTOR, prog,
0040                   ARRAY_SIZE(prog), "GPL", 0, NULL, 0);
0041     ASSERT_GE(fd, 0, "bpf_test_load_program good fd");
0042
0043     err = bpf_prog_test_run_opts(fd, &topts);
0044     ASSERT_OK(err, "test_run");
0045     ASSERT_EQ(topts.data_size_out, sizeof(flow_keys),
0046           "test_run data_size_out");
0047     ASSERT_EQ(topts.retval, 1, "test_run retval");
0048
0049     if (fd >= -1)
0050         close(fd);
0051 }