summaryrefslogtreecommitdiff
path: root/libtommath/bn_s_mp_rand_platform.c
blob: 27339bff88659930a9d1e548a65f261c2f51fc67 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
#include "tommath_private.h"
#ifdef BN_S_MP_RAND_PLATFORM_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */

/* First the OS-specific special cases
 * - *BSD
 * - Windows
 */
#if defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__) || defined(__DragonFly__)
#define BN_S_READ_ARC4RANDOM_C
static mp_err s_read_arc4random(void *p, size_t n)
{
   arc4random_buf(p, n);
   return MP_OKAY;
}
#endif

#if defined(_WIN32) || defined(_WIN32_WCE)
#define BN_S_READ_WINCSP_C

#ifndef _WIN32_WINNT
#define _WIN32_WINNT 0x0400
#endif
#ifdef _WIN32_WCE
#define UNDER_CE
#define ARM
#endif

#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <wincrypt.h>

static mp_err s_read_wincsp(void *p, size_t n)
{
   static HCRYPTPROV hProv = 0;
   if (hProv == 0) {
      HCRYPTPROV h = 0;
      if (!CryptAcquireContext(&h, NULL, MS_DEF_PROV, PROV_RSA_FULL,
                               (CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET)) &&
          !CryptAcquireContext(&h, NULL, MS_DEF_PROV, PROV_RSA_FULL,
                               CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET | CRYPT_NEWKEYSET)) {
         return MP_ERR;
      }
      hProv = h;
   }
   return CryptGenRandom(hProv, (DWORD)n, (BYTE *)p) == TRUE ? MP_OKAY : MP_ERR;
}
#endif /* WIN32 */

#if !defined(BN_S_READ_WINCSP_C) && defined(__linux__) && defined(__GLIBC_PREREQ)
#if __GLIBC_PREREQ(2, 25)
#define BN_S_READ_GETRANDOM_C
#include <sys/random.h>
#include <errno.h>

static mp_err s_read_getrandom(void *p, size_t n)
{
   char *q = (char *)p;
   while (n > 0u) {
      ssize_t ret = getrandom(q, n, 0);
      if (ret < 0) {
         if (errno == EINTR) {
            continue;
         }
         return MP_ERR;
      }
      q += ret;
      n -= (size_t)ret;
   }
   return MP_OKAY;
}
#endif
#endif

/* We assume all platforms besides windows provide "/dev/urandom".
 * In case yours doesn't, define MP_NO_DEV_URANDOM at compile-time.
 */
#if !defined(BN_S_READ_WINCSP_C) && !defined(MP_NO_DEV_URANDOM)
#define BN_S_READ_URANDOM_C
#ifndef MP_DEV_URANDOM
#define MP_DEV_URANDOM "/dev/urandom"
#endif
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>

static mp_err s_read_urandom(void *p, size_t n)
{
   int fd;
   char *q = (char *)p;

   do {
      fd = open(MP_DEV_URANDOM, O_RDONLY);
   } while ((fd == -1) && (errno == EINTR));
   if (fd == -1) return MP_ERR;

   while (n > 0u) {
      ssize_t ret = read(fd, p, n);
      if (ret < 0) {
         if (errno == EINTR) {
            continue;
         }
         close(fd);
         return MP_ERR;
      }
      q += ret;
      n -= (size_t)ret;
   }

   close(fd);
   return MP_OKAY;
}
#endif

#if defined(MP_PRNG_ENABLE_LTM_RNG)
#define BN_S_READ_LTM_RNG
unsigned long (*ltm_rng)(unsigned char *out, unsigned long outlen, void (*callback)(void));
void (*ltm_rng_callback)(void);

static mp_err s_read_ltm_rng(void *p, size_t n)
{
   unsigned long res;
   if (ltm_rng == NULL) return MP_ERR;
   res = ltm_rng(p, n, ltm_rng_callback);
   if (res != n) return MP_ERR;
   return MP_OKAY;
}
#endif

mp_err s_read_arc4random(void *p, size_t n);
mp_err s_read_wincsp(void *p, size_t n);
mp_err s_read_getrandom(void *p, size_t n);
mp_err s_read_urandom(void *p, size_t n);
mp_err s_read_ltm_rng(void *p, size_t n);

mp_err s_mp_rand_platform(void *p, size_t n)
{
   mp_err err = MP_ERR;
   if ((err != MP_OKAY) && MP_HAS(S_READ_ARC4RANDOM)) err = s_read_arc4random(p, n);
   if ((err != MP_OKAY) && MP_HAS(S_READ_WINCSP))     err = s_read_wincsp(p, n);
   if ((err != MP_OKAY) && MP_HAS(S_READ_GETRANDOM))  err = s_read_getrandom(p, n);
   if ((err != MP_OKAY) && MP_HAS(S_READ_URANDOM))    err = s_read_urandom(p, n);
   if ((err != MP_OKAY) && MP_HAS(S_READ_LTM_RNG))    err = s_read_ltm_rng(p, n);
   return err;
}

#endif