1 /*
2 * This file and its contents are supplied under the terms of the
3 * Common Development and Distribution License ("CDDL"), version 1.0.
4 * You may only use this file in accordance with the terms of version
5 * 1.0 of the CDDL.
6 *
7 * A full copy of the text of the CDDL should have accompanied this
8 * source. A copy of the CDDL is also available via the Internet at
9 * http://www.illumos.org/license/CDDL.
10 */
11
12 /*
13 * Copyright (c) 2018, Joyent, Inc.
14 */
15
16 /*
17 * getrandom system call implementation
18 */
19
20 #include <sys/types.h>
21 #include <sys/errno.h>
22 #include <sys/systm.h>
23 #include <sys/random.h>
24 #include <sys/ddi.h>
25 #include <sys/sunddi.h>
26 #include <sys/sysmacros.h>
27
28 #include <sys/random.h>
29
30 /*
31 * Impose a maximum upper bound on the number of bytes that we'll read in one
32 * go, ala a read of /dev/random. For /dev/urandom, we clamp it based on our
33 * return value, because the system call returns an int, we can't handle more
34 * than INT_MAX.
35 */
36 #define MAXRANDBYTES 1024
37 #define MAXURANDBYTES INT_MAX
38
39 ssize_t
getrandom(void * bufp,size_t buflen,unsigned int flags)40 getrandom(void *bufp, size_t buflen, unsigned int flags)
41 {
42 int out = 0;
43 uint8_t rbytes[128];
44 uint8_t *buf = bufp;
45
46 if (flags & ~(GRND_NONBLOCK | GRND_RANDOM))
47 return (set_errno(EINVAL));
48
49 if ((flags & GRND_RANDOM) && buflen > MAXRANDBYTES) {
50 buflen = MAXRANDBYTES;
51 } else if (buflen > MAXURANDBYTES) {
52 buflen = MAXURANDBYTES;
53 }
54
55 while (out < buflen) {
56 int err;
57 size_t len = MIN(sizeof (rbytes), buflen - out);
58
59 if (flags & GRND_RANDOM) {
60 if (flags & GRND_NONBLOCK)
61 err = random_get_bytes(rbytes, len);
62 else
63 err = random_get_blocking_bytes(rbytes, len);
64 } else {
65 err = random_get_pseudo_bytes(rbytes, len);
66 }
67
68 if (err == 0) {
69 if (ddi_copyout(rbytes, buf + out, len, 0) != 0)
70 return (set_errno(EFAULT));
71 out += len;
72 } else if (err == EAGAIN && out > 0) {
73 break;
74 } else {
75 return (set_errno(err));
76 }
77 }
78
79 return (out);
80 }
81