1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (c) 2019 Richard Palethorpe <rpalethorpe@suse.com>
4 *
5 * Trivial Extended Berkeley Packet Filter (eBPF) test.
6 *
7 * Sanity check loading and running bytecode.
8 *
9 * Test flow:
10 * 1. Create array map
11 * 2. Load eBPF program
12 * 3. Attach program to socket
13 * 4. Send packet on socket
14 * 5. This should trigger eBPF program which writes to array map
15 * 6. Verify array map was written to
16 */
17/*
18 * If test is executed in a loop and limit for locked memory (ulimit -l) is
19 * too low bpf() call can fail with EPERM due to deffered freeing.
20 */
21
22#include <limits.h>
23#include <string.h>
24#include <stdio.h>
25
26#include "config.h"
27#include "tst_test.h"
28#include "bpf_common.h"
29
30const char MSG[] = "Ahoj!";
31static char *msg;
32
33static char *log;
34static union bpf_attr *attr;
35
36int load_prog(int fd)
37{
38	/*
39	 * The following is a byte code template. We copy it to a guarded buffer and
40	 * substitute the runtime value of our map file descriptor.
41	 *
42	 * r0 - r10 = registers 0 to 10
43	 * r0 = return code
44	 * r1 - r5 = scratch registers, used for function arguments
45	 * r6 - r9 = registers preserved across function calls
46	 * fp/r10 = stack frame pointer
47	 */
48	struct bpf_insn PROG[] = {
49		/* Load the map FD into r1 (place holder) */
50		BPF_LD_MAP_FD(BPF_REG_1, fd),
51		/* Put (key = 0) on stack and key ptr into r2 */
52		BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),   /* r2 = fp */
53		BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),  /* r2 = r2 - 8 */
54		BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),    /* *r2 = 0 */
55		/* r0 = bpf_map_lookup_elem(r1, r2) */
56		BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
57		/* if r0 == 0 goto exit */
58		BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3),
59		/* Set map[0] = 1 */
60		BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),     /* r1 = r0 */
61		BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 1),     /* *r1 = 1 */
62		BPF_MOV64_IMM(BPF_REG_0, 0),             /* r0 = 0 */
63		BPF_EXIT_INSN(),		         /* return r0 */
64	};
65
66	bpf_init_prog_attr(attr, PROG, sizeof(PROG), log, BUFSIZE);
67	return bpf_load_prog(attr, log);
68}
69
70void setup(void)
71{
72	rlimit_bump_memlock();
73
74	memcpy(msg, MSG, sizeof(MSG));
75}
76
77void run(void)
78{
79	int map_fd, prog_fd;
80	uint32_t key = 0;
81	uint64_t val;
82
83	map_fd = bpf_map_array_create(1);
84	prog_fd = load_prog(map_fd);
85
86	bpf_run_prog(prog_fd, msg, sizeof(MSG));
87	SAFE_CLOSE(prog_fd);
88
89	bpf_map_array_get(map_fd, &key, &val);
90	if (val != 1) {
91		tst_res(TFAIL,
92			"val = %lu, but should be val = 1",
93			val);
94        } else {
95	        tst_res(TPASS, "val = 1");
96	}
97
98	SAFE_CLOSE(map_fd);
99}
100
101static struct tst_test test = {
102	.setup = setup,
103	.test_all = run,
104	.min_kver = "3.19",
105	.bufs = (struct tst_buffers []) {
106		{&log, .size = BUFSIZ},
107		{&attr, .size = sizeof(*attr)},
108		{&msg, .size = sizeof(MSG)},
109		{},
110	}
111};
112