1// SPDX-License-Identifier: GPL-2.0
2#include <test_progs.h>
3#include <network_helpers.h>
4
5void 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}
52