1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2015 Cedric Hnyda <ced.hnyda@gmail.com>
4 *
5 * Calls getrandom(2), checks that the buffer is filled with random bytes
6 * and expects success.
7 */
8
9 #include "lapi/getrandom.h"
10 #include "lapi/syscalls.h"
11 #include "tst_test.h"
12
13 #define PROC_ENTROPY_AVAIL "/proc/sys/kernel/random/entropy_avail"
14
15 static int modes[] = { 0, GRND_RANDOM, GRND_NONBLOCK,
16 GRND_RANDOM | GRND_NONBLOCK };
17
check_content(unsigned char * buf,int nb)18 static int check_content(unsigned char *buf, int nb)
19 {
20 int table[256];
21 int i, index, max;
22
23 memset(table, 0, sizeof(table));
24
25 max = 6 + nb * 0.2;
26
27 for (i = 0; i < nb; i++) {
28 index = buf[i];
29 table[index]++;
30 }
31
32 for (i = 0; i < nb; i++) {
33 if (max > 0 && table[i] > max)
34 return 0;
35 }
36 return 1;
37 }
38
verify_getrandom(unsigned int n)39 static void verify_getrandom(unsigned int n)
40 {
41 unsigned char buf[256];
42 int bufsize = 64, entropy_avail;
43
44 if (access(PROC_ENTROPY_AVAIL, F_OK) == 0) {
45 SAFE_FILE_SCANF(PROC_ENTROPY_AVAIL, "%d", &entropy_avail);
46 if (entropy_avail > 256)
47 bufsize = sizeof(buf);
48 }
49
50 memset(buf, 0, sizeof(buf));
51 do {
52 TEST(tst_syscall(__NR_getrandom, buf, bufsize, modes[n]));
53 } while ((modes[n] & GRND_NONBLOCK) && TST_RET == -1
54 && TST_ERR == EAGAIN);
55
56 if (!check_content(buf, TST_RET))
57 tst_res(TFAIL | TTERRNO, "getrandom failed");
58 else
59 tst_res(TPASS, "getrandom returned %ld", TST_RET);
60 }
61
62 static struct tst_test test = {
63 .tcnt = ARRAY_SIZE(modes),
64 .test = verify_getrandom,
65 };
66