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Paul Bakker6083fd22011-12-03 21:45:14 +00001/*
2 * Platform-specific and custom entropy polling functions
3 *
Bence Szépkúti1e148272020-08-07 13:07:28 +02004 * Copyright The Mbed TLS Contributors
Manuel Pégourié-Gonnard37ff1402015-09-04 14:21:07 +02005 * SPDX-License-Identifier: Apache-2.0
6 *
7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
8 * not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
Paul Bakker6083fd22011-12-03 21:45:14 +000018 */
19
Gilles Peskinea1f9ef02020-09-30 22:18:13 +020020#if defined(__linux__) && !defined(_GNU_SOURCE)
Nicholas Wilson2682edf2017-12-05 12:08:15 +000021/* Ensure that syscall() is available even when compiling with -std=c99 */
22#define _GNU_SOURCE
23#endif
24
Gilles Peskinedb09ef62020-06-03 01:43:33 +020025#include "common.h"
Paul Bakker6083fd22011-12-03 21:45:14 +000026
Gilles Peskine02b93292018-06-01 14:38:45 +020027#include <string.h>
28
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +020029#if defined(MBEDTLS_ENTROPY_C)
Paul Bakker6083fd22011-12-03 21:45:14 +000030
Manuel Pégourié-Gonnard7f809972015-03-09 17:05:11 +000031#include "mbedtls/entropy.h"
Chris Jonesea0a8652021-03-09 19:11:19 +000032#include "entropy_poll.h"
Janos Follath24eed8d2019-11-22 13:21:35 +000033#include "mbedtls/error.h"
Paul Bakker6083fd22011-12-03 21:45:14 +000034
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +020035#if defined(MBEDTLS_TIMING_C)
Manuel Pégourié-Gonnard7f809972015-03-09 17:05:11 +000036#include "mbedtls/timing.h"
Paul Bakker6083fd22011-12-03 21:45:14 +000037#endif
Paul Bakker9988d6b2016-06-01 11:29:42 +010038#include "mbedtls/platform.h"
Paul Bakker6083fd22011-12-03 21:45:14 +000039
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +020040#if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)
Manuel Pégourié-Gonnard325ce092016-02-22 10:33:34 +010041
42#if !defined(unix) && !defined(__unix__) && !defined(__unix) && \
Augustin Cavalier60bc47d2018-04-11 20:27:32 -040043 !defined(__APPLE__) && !defined(_WIN32) && !defined(__QNXNTO__) && \
Ørjan Malde479d8de2020-05-20 09:32:39 +000044 !defined(__HAIKU__) && !defined(__midipix__)
Gilles Peskine449bd832023-01-11 14:50:10 +010045#error \
46 "Platform entropy sources only work on Unix and Windows, see MBEDTLS_NO_PLATFORM_ENTROPY in mbedtls_config.h"
Manuel Pégourié-Gonnard325ce092016-02-22 10:33:34 +010047#endif
48
Paul Bakkerfa6a6202013-10-28 18:48:30 +010049#if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
Paul Bakker6083fd22011-12-03 21:45:14 +000050
Paul Bakker6083fd22011-12-03 21:45:14 +000051#if !defined(_WIN32_WINNT)
52#define _WIN32_WINNT 0x0400
53#endif
Paul Bakker4a2bd0d2012-11-02 11:06:08 +000054#include <windows.h>
Steve Lhomme954553f2023-06-16 13:41:48 +020055#if _WIN32_WINNT >= 0x0501 /* _WIN32_WINNT_WINXP */
Paul Bakker6083fd22011-12-03 21:45:14 +000056#include <wincrypt.h>
57
Gilles Peskine449bd832023-01-11 14:50:10 +010058int mbedtls_platform_entropy_poll(void *data, unsigned char *output, size_t len,
59 size_t *olen)
Paul Bakker6083fd22011-12-03 21:45:14 +000060{
61 HCRYPTPROV provider;
Paul Bakker6bcfc672011-12-05 13:54:00 +000062 ((void) data);
Paul Bakker6083fd22011-12-03 21:45:14 +000063 *olen = 0;
64
Gilles Peskine449bd832023-01-11 14:50:10 +010065 if (CryptAcquireContext(&provider, NULL, NULL,
66 PROV_RSA_FULL, CRYPT_VERIFYCONTEXT) == FALSE) {
67 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
Paul Bakker6083fd22011-12-03 21:45:14 +000068 }
69
Gilles Peskine449bd832023-01-11 14:50:10 +010070 if (CryptGenRandom(provider, (DWORD) len, output) == FALSE) {
71 CryptReleaseContext(provider, 0);
72 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
Attila Molnar2791ba12016-01-26 11:39:26 +010073 }
Paul Bakker6083fd22011-12-03 21:45:14 +000074
Gilles Peskine449bd832023-01-11 14:50:10 +010075 CryptReleaseContext(provider, 0);
Paul Bakker6083fd22011-12-03 21:45:14 +000076 *olen = len;
77
Gilles Peskine449bd832023-01-11 14:50:10 +010078 return 0;
Paul Bakker6083fd22011-12-03 21:45:14 +000079}
Steve Lhomme954553f2023-06-16 13:41:48 +020080#else /* !_WIN32_WINNT_WINXP */
81#error Entropy not available before Windows XP, use MBEDTLS_NO_PLATFORM_ENTROPY
82#endif /* !_WIN32_WINNT_WINXP */
Paul Bakker9af723c2014-05-01 13:03:14 +020083#else /* _WIN32 && !EFIX64 && !EFI32 */
Paul Bakker6083fd22011-12-03 21:45:14 +000084
Manuel Pégourié-Gonnard18292452015-01-09 14:34:13 +010085/*
86 * Test for Linux getrandom() support.
Gilles Peskinec6468ee2020-09-30 22:11:13 +020087 * Since there is no wrapper in the libc yet, use the generic syscall wrapper
Manuel Pégourié-Gonnard18292452015-01-09 14:34:13 +010088 * available in GNU libc and compatible libc's (eg uClibc).
89 */
Gilles Peskinec6468ee2020-09-30 22:11:13 +020090#if ((defined(__linux__) && defined(__GLIBC__)) || defined(__midipix__))
Manuel Pégourié-Gonnard18292452015-01-09 14:34:13 +010091#include <unistd.h>
92#include <sys/syscall.h>
93#if defined(SYS_getrandom)
94#define HAVE_GETRANDOM
Hanno Becker27516972018-10-18 11:49:25 +010095#include <errno.h>
Manuel Pégourié-Gonnardbcf13ba2015-06-22 18:06:17 +020096
Gilles Peskine449bd832023-01-11 14:50:10 +010097static int getrandom_wrapper(void *buf, size_t buflen, unsigned int flags)
Manuel Pégourié-Gonnard18292452015-01-09 14:34:13 +010098{
Manuel Pégourié-Gonnardbcf13ba2015-06-22 18:06:17 +020099 /* MemSan cannot understand that the syscall writes to the buffer */
100#if defined(__has_feature)
101#if __has_feature(memory_sanitizer)
Gilles Peskine449bd832023-01-11 14:50:10 +0100102 memset(buf, 0, buflen);
Manuel Pégourié-Gonnardbcf13ba2015-06-22 18:06:17 +0200103#endif
104#endif
Gilles Peskine449bd832023-01-11 14:50:10 +0100105 return syscall(SYS_getrandom, buf, buflen, flags);
Manuel Pégourié-Gonnard18292452015-01-09 14:34:13 +0100106}
Manuel Pégourié-Gonnardd97828e2015-04-29 14:03:28 +0200107#endif /* SYS_getrandom */
Ørjan Malde479d8de2020-05-20 09:32:39 +0000108#endif /* __linux__ || __midipix__ */
Manuel Pégourié-Gonnard18292452015-01-09 14:34:13 +0100109
David Carlier2b8c2652020-12-28 15:51:14 +0000110#if defined(__FreeBSD__) || defined(__DragonFly__)
111#include <sys/param.h>
112#if (defined(__FreeBSD__) && __FreeBSD_version >= 1200000) || \
113 (defined(__DragonFly__) && __DragonFly_version >= 500700)
114#include <errno.h>
115#include <sys/random.h>
116#define HAVE_GETRANDOM
Gilles Peskine449bd832023-01-11 14:50:10 +0100117static int getrandom_wrapper(void *buf, size_t buflen, unsigned int flags)
David Carlier2b8c2652020-12-28 15:51:14 +0000118{
Gilles Peskine449bd832023-01-11 14:50:10 +0100119 return getrandom(buf, buflen, flags);
David Carlier2b8c2652020-12-28 15:51:14 +0000120}
121#endif /* (__FreeBSD__ && __FreeBSD_version >= 1200000) ||
122 (__DragonFly__ && __DragonFly_version >= 500700) */
123#endif /* __FreeBSD__ || __DragonFly__ */
124
nia9f5312c2020-06-11 13:32:13 +0100125/*
126 * Some BSD systems provide KERN_ARND.
127 * This is equivalent to reading from /dev/urandom, only it doesn't require an
128 * open file descriptor, and provides up to 256 bytes per call (basically the
129 * same as getentropy(), but with a longer history).
130 *
131 * Documentation: https://netbsd.gw.com/cgi-bin/man-cgi?sysctl+7
132 */
133#if (defined(__FreeBSD__) || defined(__NetBSD__)) && !defined(HAVE_GETRANDOM)
134#include <sys/param.h>
135#include <sys/sysctl.h>
136#if defined(KERN_ARND)
137#define HAVE_SYSCTL_ARND
138
Gilles Peskine449bd832023-01-11 14:50:10 +0100139static int sysctl_arnd_wrapper(unsigned char *buf, size_t buflen)
nia9f5312c2020-06-11 13:32:13 +0100140{
141 int name[2];
142 size_t len;
143
144 name[0] = CTL_KERN;
145 name[1] = KERN_ARND;
146
Gilles Peskine449bd832023-01-11 14:50:10 +0100147 while (buflen > 0) {
nia9f5312c2020-06-11 13:32:13 +0100148 len = buflen > 256 ? 256 : buflen;
Gilles Peskine449bd832023-01-11 14:50:10 +0100149 if (sysctl(name, 2, buf, &len, NULL, 0) == -1) {
150 return -1;
151 }
nia9f5312c2020-06-11 13:32:13 +0100152 buflen -= len;
nia8373c862020-06-24 17:15:02 +0100153 buf += len;
nia9f5312c2020-06-11 13:32:13 +0100154 }
Gilles Peskine449bd832023-01-11 14:50:10 +0100155 return 0;
nia9f5312c2020-06-11 13:32:13 +0100156}
157#endif /* KERN_ARND */
158#endif /* __FreeBSD__ || __NetBSD__ */
159
Paul Bakker6083fd22011-12-03 21:45:14 +0000160#include <stdio.h>
161
Gilles Peskine449bd832023-01-11 14:50:10 +0100162int mbedtls_platform_entropy_poll(void *data,
163 unsigned char *output, size_t len, size_t *olen)
Paul Bakker6083fd22011-12-03 21:45:14 +0000164{
165 FILE *file;
Manuel Pégourié-Gonnardea356662015-08-27 12:02:40 +0200166 size_t read_len;
Janos Follath24eed8d2019-11-22 13:21:35 +0000167 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
Paul Bakker6083fd22011-12-03 21:45:14 +0000168 ((void) data);
169
Manuel Pégourié-Gonnardd97828e2015-04-29 14:03:28 +0200170#if defined(HAVE_GETRANDOM)
Gilles Peskine449bd832023-01-11 14:50:10 +0100171 ret = getrandom_wrapper(output, len, 0);
172 if (ret >= 0) {
Manuel Pégourié-Gonnardd97828e2015-04-29 14:03:28 +0200173 *olen = ret;
Gilles Peskine449bd832023-01-11 14:50:10 +0100174 return 0;
175 } else if (errno != ENOSYS) {
176 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
Manuel Pégourié-Gonnardd97828e2015-04-29 14:03:28 +0200177 }
Hanno Becker27516972018-10-18 11:49:25 +0100178 /* Fall through if the system call isn't known. */
179#else
Hanno Becker9772da82018-11-05 11:43:07 +0000180 ((void) ret);
Manuel Pégourié-Gonnardd97828e2015-04-29 14:03:28 +0200181#endif /* HAVE_GETRANDOM */
182
nia9f5312c2020-06-11 13:32:13 +0100183#if defined(HAVE_SYSCTL_ARND)
184 ((void) file);
185 ((void) read_len);
Gilles Peskine449bd832023-01-11 14:50:10 +0100186 if (sysctl_arnd_wrapper(output, len) == -1) {
187 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
188 }
nia9f5312c2020-06-11 13:32:13 +0100189 *olen = len;
Gilles Peskine449bd832023-01-11 14:50:10 +0100190 return 0;
nia9f5312c2020-06-11 13:32:13 +0100191#else
192
Paul Bakker6083fd22011-12-03 21:45:14 +0000193 *olen = 0;
194
Gilles Peskine449bd832023-01-11 14:50:10 +0100195 file = fopen("/dev/urandom", "rb");
196 if (file == NULL) {
197 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
Paul Bakker6083fd22011-12-03 21:45:14 +0000198 }
199
Gilles Peskine449bd832023-01-11 14:50:10 +0100200 /* Ensure no stdio buffering of secrets, as such buffers cannot be wiped. */
201 mbedtls_setbuf(file, NULL);
202
203 read_len = fread(output, 1, len, file);
204 if (read_len != len) {
205 fclose(file);
206 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
207 }
208
209 fclose(file);
Paul Bakker6083fd22011-12-03 21:45:14 +0000210 *olen = len;
211
Gilles Peskine449bd832023-01-11 14:50:10 +0100212 return 0;
nia9f5312c2020-06-11 13:32:13 +0100213#endif /* HAVE_SYSCTL_ARND */
Paul Bakker6083fd22011-12-03 21:45:14 +0000214}
Paul Bakker9af723c2014-05-01 13:03:14 +0200215#endif /* _WIN32 && !EFIX64 && !EFI32 */
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200216#endif /* !MBEDTLS_NO_PLATFORM_ENTROPY */
Paul Bakker6083fd22011-12-03 21:45:14 +0000217
Paul Bakker9988d6b2016-06-01 11:29:42 +0100218#if defined(MBEDTLS_ENTROPY_NV_SEED)
Gilles Peskine449bd832023-01-11 14:50:10 +0100219int mbedtls_nv_seed_poll(void *data,
220 unsigned char *output, size_t len, size_t *olen)
Paul Bakker9988d6b2016-06-01 11:29:42 +0100221{
222 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
223 size_t use_len = MBEDTLS_ENTROPY_BLOCK_SIZE;
224 ((void) data);
225
Gilles Peskine449bd832023-01-11 14:50:10 +0100226 memset(buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE);
Paul Bakker9988d6b2016-06-01 11:29:42 +0100227
Gilles Peskine449bd832023-01-11 14:50:10 +0100228 if (mbedtls_nv_seed_read(buf, MBEDTLS_ENTROPY_BLOCK_SIZE) < 0) {
229 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
230 }
Paul Bakker9988d6b2016-06-01 11:29:42 +0100231
Gilles Peskine449bd832023-01-11 14:50:10 +0100232 if (len < use_len) {
233 use_len = len;
234 }
Paul Bakker9988d6b2016-06-01 11:29:42 +0100235
Gilles Peskine449bd832023-01-11 14:50:10 +0100236 memcpy(output, buf, use_len);
Paul Bakker9988d6b2016-06-01 11:29:42 +0100237 *olen = use_len;
238
Gilles Peskine449bd832023-01-11 14:50:10 +0100239 return 0;
Paul Bakker9988d6b2016-06-01 11:29:42 +0100240}
241#endif /* MBEDTLS_ENTROPY_NV_SEED */
242
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200243#endif /* MBEDTLS_ENTROPY_C */