1 /***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
9 *
10 * This software is licensed as described in the file COPYING, which
11 * you should have received as part of this distribution. The terms
12 * are also available at https://curl.se/docs/copyright.html.
13 *
14 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
15 * copies of the Software, and permit persons to whom the Software is
16 * furnished to do so, under the terms of the COPYING file.
17 *
18 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
19 * KIND, either express or implied.
20 *
21 * SPDX-License-Identifier: curl
22 *
23 ***************************************************************************/
24
25 #include "curl_setup.h"
26
27 #include <limits.h>
28
29 #ifdef HAVE_FCNTL_H
30 #include <fcntl.h>
31 #endif
32 #ifdef HAVE_ARPA_INET_H
33 #include <arpa/inet.h>
34 #endif
35
36 #include <curl/curl.h>
37 #include "urldata.h"
38 #include "vtls/vtls.h"
39 #include "sendf.h"
40 #include "timeval.h"
41 #include "rand.h"
42 #include "escape.h"
43
44 /* The last 3 #include files should be in this order */
45 #include "curl_printf.h"
46 #include "curl_memory.h"
47 #include "memdebug.h"
48
49 #ifdef _WIN32
50
51 #if defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x600 && \
52 !defined(CURL_WINDOWS_UWP)
53 # define HAVE_WIN_BCRYPTGENRANDOM
54 # include <bcrypt.h>
55 # ifdef _MSC_VER
56 # pragma comment(lib, "bcrypt.lib")
57 # endif
58 # ifndef BCRYPT_USE_SYSTEM_PREFERRED_RNG
59 # define BCRYPT_USE_SYSTEM_PREFERRED_RNG 0x00000002
60 # endif
61 # ifndef STATUS_SUCCESS
62 # define STATUS_SUCCESS ((NTSTATUS)0x00000000L)
63 # endif
64 #elif defined(USE_WIN32_CRYPTO)
65 # include <wincrypt.h>
66 # ifdef _MSC_VER
67 # pragma comment(lib, "advapi32.lib")
68 # endif
69 #endif
70
Curl_win32_random(unsigned char * entropy,size_t length)71 CURLcode Curl_win32_random(unsigned char *entropy, size_t length)
72 {
73 memset(entropy, 0, length);
74
75 #if defined(HAVE_WIN_BCRYPTGENRANDOM)
76 if(BCryptGenRandom(NULL, entropy, (ULONG)length,
77 BCRYPT_USE_SYSTEM_PREFERRED_RNG) != STATUS_SUCCESS)
78 return CURLE_FAILED_INIT;
79
80 return CURLE_OK;
81 #elif defined(USE_WIN32_CRYPTO)
82 {
83 HCRYPTPROV hCryptProv = 0;
84
85 if(!CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL,
86 CRYPT_VERIFYCONTEXT | CRYPT_SILENT))
87 return CURLE_FAILED_INIT;
88
89 if(!CryptGenRandom(hCryptProv, (DWORD)length, entropy)) {
90 CryptReleaseContext(hCryptProv, 0UL);
91 return CURLE_FAILED_INIT;
92 }
93
94 CryptReleaseContext(hCryptProv, 0UL);
95 }
96 return CURLE_OK;
97 #else
98 return CURLE_NOT_BUILT_IN;
99 #endif
100 }
101 #endif
102
103 #if !defined(USE_SSL)
104 /* ---- possibly non-cryptographic version following ---- */
weak_random(struct Curl_easy * data,unsigned char * entropy,size_t length)105 static CURLcode weak_random(struct Curl_easy *data,
106 unsigned char *entropy,
107 size_t length) /* always 4, size of int */
108 {
109 unsigned int r;
110 DEBUGASSERT(length == sizeof(int));
111
112 /* Trying cryptographically secure functions first */
113 #ifdef _WIN32
114 (void)data;
115 {
116 CURLcode result = Curl_win32_random(entropy, length);
117 if(result != CURLE_NOT_BUILT_IN)
118 return result;
119 }
120 #endif
121
122 #if defined(HAVE_ARC4RANDOM)
123 (void)data;
124 r = (unsigned int)arc4random();
125 memcpy(entropy, &r, length);
126 #else
127 infof(data, "WARNING: using weak random seed");
128 {
129 static unsigned int randseed;
130 static bool seeded = FALSE;
131 unsigned int rnd;
132 if(!seeded) {
133 struct curltime now = Curl_now();
134 randseed += (unsigned int)now.tv_usec + (unsigned int)now.tv_sec;
135 randseed = randseed * 1103515245 + 12345;
136 randseed = randseed * 1103515245 + 12345;
137 randseed = randseed * 1103515245 + 12345;
138 seeded = TRUE;
139 }
140
141 /* Return an unsigned 32-bit pseudo-random number. */
142 r = randseed = randseed * 1103515245 + 12345;
143 rnd = (r << 16) | ((r >> 16) & 0xFFFF);
144 memcpy(entropy, &rnd, length);
145 }
146 #endif
147 return CURLE_OK;
148 }
149 #endif
150
151 #ifdef USE_SSL
152 #define _random(x,y,z) Curl_ssl_random(x,y,z)
153 #else
154 #define _random(x,y,z) weak_random(x,y,z)
155 #endif
156
randit(struct Curl_easy * data,unsigned int * rnd,bool env_override)157 static CURLcode randit(struct Curl_easy *data, unsigned int *rnd,
158 bool env_override)
159 {
160 #ifdef DEBUGBUILD
161 if(env_override) {
162 char *force_entropy = getenv("CURL_ENTROPY");
163 if(force_entropy) {
164 static unsigned int randseed;
165 static bool seeded = FALSE;
166
167 if(!seeded) {
168 unsigned int seed = 0;
169 size_t elen = strlen(force_entropy);
170 size_t clen = sizeof(seed);
171 size_t min = elen < clen ? elen : clen;
172 memcpy((char *)&seed, force_entropy, min);
173 randseed = ntohl(seed);
174 seeded = TRUE;
175 }
176 else
177 randseed++;
178 *rnd = randseed;
179 return CURLE_OK;
180 }
181 }
182 #else
183 (void)env_override;
184 #endif
185
186 /* data may be NULL! */
187 return _random(data, (unsigned char *)rnd, sizeof(*rnd));
188 }
189
190 /*
191 * Curl_rand() stores 'num' number of random unsigned characters in the buffer
192 * 'rnd' points to.
193 *
194 * If libcurl is built without TLS support or with a TLS backend that lacks a
195 * proper random API (Rustls or mbedTLS), this function will use "weak"
196 * random.
197 *
198 * When built *with* TLS support and a backend that offers strong random, it
199 * will return error if it cannot provide strong random values.
200 *
201 * NOTE: 'data' may be passed in as NULL when coming from external API without
202 * easy handle!
203 *
204 */
205
Curl_rand_bytes(struct Curl_easy * data,bool env_override,unsigned char * rnd,size_t num)206 CURLcode Curl_rand_bytes(struct Curl_easy *data,
207 #ifdef DEBUGBUILD
208 bool env_override,
209 #endif
210 unsigned char *rnd, size_t num)
211 {
212 CURLcode result = CURLE_BAD_FUNCTION_ARGUMENT;
213 #ifndef DEBUGBUILD
214 const bool env_override = FALSE;
215 #endif
216
217 DEBUGASSERT(num);
218
219 while(num) {
220 unsigned int r;
221 size_t left = num < sizeof(unsigned int) ? num : sizeof(unsigned int);
222
223 result = randit(data, &r, env_override);
224 if(result)
225 return result;
226
227 while(left) {
228 *rnd++ = (unsigned char)(r & 0xFF);
229 r >>= 8;
230 --num;
231 --left;
232 }
233 }
234
235 return result;
236 }
237
238 /*
239 * Curl_rand_hex() fills the 'rnd' buffer with a given 'num' size with random
240 * hexadecimal digits PLUS a null-terminating byte. It must be an odd number
241 * size.
242 */
243
Curl_rand_hex(struct Curl_easy * data,unsigned char * rnd,size_t num)244 CURLcode Curl_rand_hex(struct Curl_easy *data, unsigned char *rnd,
245 size_t num)
246 {
247 CURLcode result = CURLE_BAD_FUNCTION_ARGUMENT;
248 unsigned char buffer[128];
249 DEBUGASSERT(num > 1);
250
251 #ifdef __clang_analyzer__
252 /* This silences a scan-build warning about accessing this buffer with
253 uninitialized memory. */
254 memset(buffer, 0, sizeof(buffer));
255 #endif
256
257 if((num/2 >= sizeof(buffer)) || !(num&1)) {
258 /* make sure it fits in the local buffer and that it is an odd number! */
259 DEBUGF(infof(data, "invalid buffer size with Curl_rand_hex"));
260 return CURLE_BAD_FUNCTION_ARGUMENT;
261 }
262
263 num--; /* save one for null-termination */
264
265 result = Curl_rand(data, buffer, num/2);
266 if(result)
267 return result;
268
269 Curl_hexencode(buffer, num/2, rnd, num + 1);
270 return result;
271 }
272
273 /*
274 * Curl_rand_alnum() fills the 'rnd' buffer with a given 'num' size with random
275 * alphanumerical chars PLUS a null-terminating byte.
276 */
277
278 static const char alnum[] =
279 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
280
Curl_rand_alnum(struct Curl_easy * data,unsigned char * rnd,size_t num)281 CURLcode Curl_rand_alnum(struct Curl_easy *data, unsigned char *rnd,
282 size_t num)
283 {
284 CURLcode result = CURLE_OK;
285 const unsigned int alnumspace = sizeof(alnum) - 1;
286 unsigned int r;
287 DEBUGASSERT(num > 1);
288
289 num--; /* save one for null-termination */
290
291 while(num) {
292 do {
293 result = randit(data, &r, TRUE);
294 if(result)
295 return result;
296 } while(r >= (UINT_MAX - UINT_MAX % alnumspace));
297
298 *rnd++ = (unsigned char)alnum[r % alnumspace];
299 num--;
300 }
301 *rnd = 0;
302
303 return result;
304 }
305
