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9425cb9e | 1 | /* One way encryption based on SHA256 sum. |
2b778ceb | 2 | Copyright (C) 2007-2021 Free Software Foundation, Inc. |
9425cb9e UD |
3 | This file is part of the GNU C Library. |
4 | Contributed by Ulrich Drepper <drepper@redhat.com>, 2007. | |
5 | ||
6 | The GNU C Library is free software; you can redistribute it and/or | |
7 | modify it under the terms of the GNU Lesser General Public | |
8 | License as published by the Free Software Foundation; either | |
9 | version 2.1 of the License, or (at your option) any later version. | |
10 | ||
11 | The GNU C Library is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | Lesser General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Lesser General Public | |
59ba27a6 | 17 | License along with the GNU C Library; if not, see |
5a82c748 | 18 | <https://www.gnu.org/licenses/>. */ |
9425cb9e UD |
19 | |
20 | #include <assert.h> | |
21 | #include <errno.h> | |
22 | #include <stdbool.h> | |
23 | #include <stdlib.h> | |
24 | #include <string.h> | |
e054f494 | 25 | #include <stdint.h> |
9425cb9e UD |
26 | #include <sys/param.h> |
27 | ||
28 | #include "sha256.h" | |
8747cd03 | 29 | #include "crypt-private.h" |
9425cb9e UD |
30 | |
31 | ||
ff886b82 UD |
32 | #ifdef USE_NSS |
33 | typedef int PRBool; | |
34 | # include <hasht.h> | |
35 | # include <nsslowhash.h> | |
36 | ||
37 | # define sha256_init_ctx(ctxp, nss_ctxp) \ | |
38 | do \ | |
39 | { \ | |
40 | if (((nss_ctxp = NSSLOWHASH_NewContext (nss_ictx, HASH_AlgSHA256)) \ | |
41 | == NULL)) \ | |
42 | { \ | |
43 | if (nss_ctx != NULL) \ | |
44 | NSSLOWHASH_Destroy (nss_ctx); \ | |
45 | if (nss_alt_ctx != NULL) \ | |
46 | NSSLOWHASH_Destroy (nss_alt_ctx); \ | |
47 | return NULL; \ | |
48 | } \ | |
49 | NSSLOWHASH_Begin (nss_ctxp); \ | |
50 | } \ | |
51 | while (0) | |
52 | ||
53 | # define sha256_process_bytes(buf, len, ctxp, nss_ctxp) \ | |
54 | NSSLOWHASH_Update (nss_ctxp, (const unsigned char *) buf, len) | |
55 | ||
56 | # define sha256_finish_ctx(ctxp, nss_ctxp, result) \ | |
57 | do \ | |
58 | { \ | |
59 | unsigned int ret; \ | |
60 | NSSLOWHASH_End (nss_ctxp, result, &ret, sizeof (result)); \ | |
61 | assert (ret == sizeof (result)); \ | |
62 | NSSLOWHASH_Destroy (nss_ctxp); \ | |
63 | nss_ctxp = NULL; \ | |
64 | } \ | |
65 | while (0) | |
66 | #else | |
67 | # define sha256_init_ctx(ctxp, nss_ctxp) \ | |
68 | __sha256_init_ctx (ctxp) | |
69 | ||
70 | # define sha256_process_bytes(buf, len, ctxp, nss_ctxp) \ | |
71 | __sha256_process_bytes(buf, len, ctxp) | |
72 | ||
73 | # define sha256_finish_ctx(ctxp, nss_ctxp, result) \ | |
74 | __sha256_finish_ctx (ctxp, result) | |
75 | #endif | |
76 | ||
77 | ||
9425cb9e UD |
78 | /* Define our magic string to mark salt for SHA256 "encryption" |
79 | replacement. */ | |
80 | static const char sha256_salt_prefix[] = "$5$"; | |
81 | ||
82 | /* Prefix for optional rounds specification. */ | |
83 | static const char sha256_rounds_prefix[] = "rounds="; | |
84 | ||
85 | /* Maximum salt string length. */ | |
86 | #define SALT_LEN_MAX 16 | |
87 | /* Default number of rounds if not explicitly specified. */ | |
88 | #define ROUNDS_DEFAULT 5000 | |
89 | /* Minimum number of rounds. */ | |
90 | #define ROUNDS_MIN 1000 | |
91 | /* Maximum number of rounds. */ | |
92 | #define ROUNDS_MAX 999999999 | |
93 | ||
9425cb9e UD |
94 | |
95 | /* Prototypes for local functions. */ | |
96 | extern char *__sha256_crypt_r (const char *key, const char *salt, | |
97 | char *buffer, int buflen); | |
98 | extern char *__sha256_crypt (const char *key, const char *salt); | |
99 | ||
100 | ||
101 | char * | |
9dd346ff | 102 | __sha256_crypt_r (const char *key, const char *salt, char *buffer, int buflen) |
9425cb9e UD |
103 | { |
104 | unsigned char alt_result[32] | |
105 | __attribute__ ((__aligned__ (__alignof__ (uint32_t)))); | |
106 | unsigned char temp_result[32] | |
107 | __attribute__ ((__aligned__ (__alignof__ (uint32_t)))); | |
9425cb9e UD |
108 | size_t salt_len; |
109 | size_t key_len; | |
110 | size_t cnt; | |
111 | char *cp; | |
112 | char *copied_key = NULL; | |
113 | char *copied_salt = NULL; | |
114 | char *p_bytes; | |
115 | char *s_bytes; | |
116 | /* Default number of rounds. */ | |
117 | size_t rounds = ROUNDS_DEFAULT; | |
118 | bool rounds_custom = false; | |
b8dc394d JL |
119 | size_t alloca_used = 0; |
120 | char *free_key = NULL; | |
121 | char *free_pbytes = NULL; | |
9425cb9e UD |
122 | |
123 | /* Find beginning of salt string. The prefix should normally always | |
124 | be present. Just in case it is not. */ | |
125 | if (strncmp (sha256_salt_prefix, salt, sizeof (sha256_salt_prefix) - 1) == 0) | |
126 | /* Skip salt prefix. */ | |
127 | salt += sizeof (sha256_salt_prefix) - 1; | |
128 | ||
129 | if (strncmp (salt, sha256_rounds_prefix, sizeof (sha256_rounds_prefix) - 1) | |
130 | == 0) | |
131 | { | |
132 | const char *num = salt + sizeof (sha256_rounds_prefix) - 1; | |
133 | char *endp; | |
134 | unsigned long int srounds = strtoul (num, &endp, 10); | |
135 | if (*endp == '$') | |
136 | { | |
137 | salt = endp + 1; | |
138 | rounds = MAX (ROUNDS_MIN, MIN (srounds, ROUNDS_MAX)); | |
139 | rounds_custom = true; | |
140 | } | |
141 | } | |
142 | ||
143 | salt_len = MIN (strcspn (salt, "$"), SALT_LEN_MAX); | |
144 | key_len = strlen (key); | |
145 | ||
146 | if ((key - (char *) 0) % __alignof__ (uint32_t) != 0) | |
147 | { | |
b8dc394d JL |
148 | char *tmp; |
149 | ||
150 | if (__libc_use_alloca (alloca_used + key_len + __alignof__ (uint32_t))) | |
151 | tmp = alloca_account (key_len + __alignof__ (uint32_t), alloca_used); | |
152 | else | |
153 | { | |
154 | free_key = tmp = (char *) malloc (key_len + __alignof__ (uint32_t)); | |
155 | if (tmp == NULL) | |
156 | return NULL; | |
157 | } | |
158 | ||
9425cb9e UD |
159 | key = copied_key = |
160 | memcpy (tmp + __alignof__ (uint32_t) | |
161 | - (tmp - (char *) 0) % __alignof__ (uint32_t), | |
162 | key, key_len); | |
163 | assert ((key - (char *) 0) % __alignof__ (uint32_t) == 0); | |
164 | } | |
165 | ||
166 | if ((salt - (char *) 0) % __alignof__ (uint32_t) != 0) | |
167 | { | |
168 | char *tmp = (char *) alloca (salt_len + __alignof__ (uint32_t)); | |
b8dc394d | 169 | alloca_used += salt_len + __alignof__ (uint32_t); |
9425cb9e UD |
170 | salt = copied_salt = |
171 | memcpy (tmp + __alignof__ (uint32_t) | |
172 | - (tmp - (char *) 0) % __alignof__ (uint32_t), | |
173 | salt, salt_len); | |
174 | assert ((salt - (char *) 0) % __alignof__ (uint32_t) == 0); | |
175 | } | |
176 | ||
ff886b82 UD |
177 | #ifdef USE_NSS |
178 | /* Initialize libfreebl3. */ | |
179 | NSSLOWInitContext *nss_ictx = NSSLOW_Init (); | |
180 | if (nss_ictx == NULL) | |
b8dc394d JL |
181 | { |
182 | free (free_key); | |
183 | return NULL; | |
184 | } | |
ff886b82 UD |
185 | NSSLOWHASHContext *nss_ctx = NULL; |
186 | NSSLOWHASHContext *nss_alt_ctx = NULL; | |
187 | #else | |
188 | struct sha256_ctx ctx; | |
189 | struct sha256_ctx alt_ctx; | |
190 | #endif | |
191 | ||
9425cb9e | 192 | /* Prepare for the real work. */ |
ff886b82 | 193 | sha256_init_ctx (&ctx, nss_ctx); |
9425cb9e UD |
194 | |
195 | /* Add the key string. */ | |
ff886b82 | 196 | sha256_process_bytes (key, key_len, &ctx, nss_ctx); |
9425cb9e | 197 | |
7f745396 UD |
198 | /* The last part is the salt string. This must be at most 16 |
199 | characters and it ends at the first `$' character. */ | |
ff886b82 | 200 | sha256_process_bytes (salt, salt_len, &ctx, nss_ctx); |
9425cb9e UD |
201 | |
202 | ||
203 | /* Compute alternate SHA256 sum with input KEY, SALT, and KEY. The | |
204 | final result will be added to the first context. */ | |
ff886b82 | 205 | sha256_init_ctx (&alt_ctx, nss_alt_ctx); |
9425cb9e UD |
206 | |
207 | /* Add key. */ | |
ff886b82 | 208 | sha256_process_bytes (key, key_len, &alt_ctx, nss_alt_ctx); |
9425cb9e UD |
209 | |
210 | /* Add salt. */ | |
ff886b82 | 211 | sha256_process_bytes (salt, salt_len, &alt_ctx, nss_alt_ctx); |
9425cb9e UD |
212 | |
213 | /* Add key again. */ | |
ff886b82 | 214 | sha256_process_bytes (key, key_len, &alt_ctx, nss_alt_ctx); |
9425cb9e UD |
215 | |
216 | /* Now get result of this (32 bytes) and add it to the other | |
217 | context. */ | |
ff886b82 | 218 | sha256_finish_ctx (&alt_ctx, nss_alt_ctx, alt_result); |
9425cb9e UD |
219 | |
220 | /* Add for any character in the key one byte of the alternate sum. */ | |
221 | for (cnt = key_len; cnt > 32; cnt -= 32) | |
ff886b82 UD |
222 | sha256_process_bytes (alt_result, 32, &ctx, nss_ctx); |
223 | sha256_process_bytes (alt_result, cnt, &ctx, nss_ctx); | |
9425cb9e UD |
224 | |
225 | /* Take the binary representation of the length of the key and for every | |
226 | 1 add the alternate sum, for every 0 the key. */ | |
227 | for (cnt = key_len; cnt > 0; cnt >>= 1) | |
228 | if ((cnt & 1) != 0) | |
ff886b82 | 229 | sha256_process_bytes (alt_result, 32, &ctx, nss_ctx); |
9425cb9e | 230 | else |
ff886b82 | 231 | sha256_process_bytes (key, key_len, &ctx, nss_ctx); |
9425cb9e UD |
232 | |
233 | /* Create intermediate result. */ | |
ff886b82 | 234 | sha256_finish_ctx (&ctx, nss_ctx, alt_result); |
9425cb9e UD |
235 | |
236 | /* Start computation of P byte sequence. */ | |
ff886b82 | 237 | sha256_init_ctx (&alt_ctx, nss_alt_ctx); |
9425cb9e UD |
238 | |
239 | /* For every character in the password add the entire password. */ | |
240 | for (cnt = 0; cnt < key_len; ++cnt) | |
ff886b82 | 241 | sha256_process_bytes (key, key_len, &alt_ctx, nss_alt_ctx); |
9425cb9e UD |
242 | |
243 | /* Finish the digest. */ | |
ff886b82 | 244 | sha256_finish_ctx (&alt_ctx, nss_alt_ctx, temp_result); |
9425cb9e UD |
245 | |
246 | /* Create byte sequence P. */ | |
b8dc394d JL |
247 | if (__libc_use_alloca (alloca_used + key_len)) |
248 | cp = p_bytes = (char *) alloca (key_len); | |
249 | else | |
250 | { | |
251 | free_pbytes = cp = p_bytes = (char *)malloc (key_len); | |
252 | if (free_pbytes == NULL) | |
253 | { | |
254 | free (free_key); | |
255 | return NULL; | |
256 | } | |
257 | } | |
258 | ||
9425cb9e UD |
259 | for (cnt = key_len; cnt >= 32; cnt -= 32) |
260 | cp = mempcpy (cp, temp_result, 32); | |
261 | memcpy (cp, temp_result, cnt); | |
262 | ||
263 | /* Start computation of S byte sequence. */ | |
ff886b82 | 264 | sha256_init_ctx (&alt_ctx, nss_alt_ctx); |
9425cb9e UD |
265 | |
266 | /* For every character in the password add the entire password. */ | |
267 | for (cnt = 0; cnt < 16 + alt_result[0]; ++cnt) | |
ff886b82 | 268 | sha256_process_bytes (salt, salt_len, &alt_ctx, nss_alt_ctx); |
9425cb9e UD |
269 | |
270 | /* Finish the digest. */ | |
ff886b82 | 271 | sha256_finish_ctx (&alt_ctx, nss_alt_ctx, temp_result); |
9425cb9e UD |
272 | |
273 | /* Create byte sequence S. */ | |
274 | cp = s_bytes = alloca (salt_len); | |
275 | for (cnt = salt_len; cnt >= 32; cnt -= 32) | |
276 | cp = mempcpy (cp, temp_result, 32); | |
277 | memcpy (cp, temp_result, cnt); | |
278 | ||
279 | /* Repeatedly run the collected hash value through SHA256 to burn | |
280 | CPU cycles. */ | |
281 | for (cnt = 0; cnt < rounds; ++cnt) | |
282 | { | |
283 | /* New context. */ | |
ff886b82 | 284 | sha256_init_ctx (&ctx, nss_ctx); |
9425cb9e UD |
285 | |
286 | /* Add key or last result. */ | |
287 | if ((cnt & 1) != 0) | |
ff886b82 | 288 | sha256_process_bytes (p_bytes, key_len, &ctx, nss_ctx); |
9425cb9e | 289 | else |
ff886b82 | 290 | sha256_process_bytes (alt_result, 32, &ctx, nss_ctx); |
9425cb9e UD |
291 | |
292 | /* Add salt for numbers not divisible by 3. */ | |
293 | if (cnt % 3 != 0) | |
ff886b82 | 294 | sha256_process_bytes (s_bytes, salt_len, &ctx, nss_ctx); |
9425cb9e UD |
295 | |
296 | /* Add key for numbers not divisible by 7. */ | |
297 | if (cnt % 7 != 0) | |
ff886b82 | 298 | sha256_process_bytes (p_bytes, key_len, &ctx, nss_ctx); |
9425cb9e UD |
299 | |
300 | /* Add key or last result. */ | |
301 | if ((cnt & 1) != 0) | |
ff886b82 | 302 | sha256_process_bytes (alt_result, 32, &ctx, nss_ctx); |
9425cb9e | 303 | else |
ff886b82 | 304 | sha256_process_bytes (p_bytes, key_len, &ctx, nss_ctx); |
9425cb9e UD |
305 | |
306 | /* Create intermediate result. */ | |
ff886b82 | 307 | sha256_finish_ctx (&ctx, nss_ctx, alt_result); |
9425cb9e UD |
308 | } |
309 | ||
ff886b82 UD |
310 | #ifdef USE_NSS |
311 | /* Free libfreebl3 resources. */ | |
312 | NSSLOW_Shutdown (nss_ictx); | |
313 | #endif | |
314 | ||
9425cb9e UD |
315 | /* Now we can construct the result string. It consists of three |
316 | parts. */ | |
317 | cp = __stpncpy (buffer, sha256_salt_prefix, MAX (0, buflen)); | |
318 | buflen -= sizeof (sha256_salt_prefix) - 1; | |
319 | ||
320 | if (rounds_custom) | |
321 | { | |
61158ffa JM |
322 | int n = __snprintf (cp, MAX (0, buflen), "%s%zu$", |
323 | sha256_rounds_prefix, rounds); | |
9425cb9e UD |
324 | cp += n; |
325 | buflen -= n; | |
326 | } | |
327 | ||
328 | cp = __stpncpy (cp, salt, MIN ((size_t) MAX (0, buflen), salt_len)); | |
329 | buflen -= MIN ((size_t) MAX (0, buflen), salt_len); | |
330 | ||
331 | if (buflen > 0) | |
332 | { | |
333 | *cp++ = '$'; | |
334 | --buflen; | |
335 | } | |
336 | ||
8747cd03 KS |
337 | __b64_from_24bit (&cp, &buflen, |
338 | alt_result[0], alt_result[10], alt_result[20], 4); | |
339 | __b64_from_24bit (&cp, &buflen, | |
340 | alt_result[21], alt_result[1], alt_result[11], 4); | |
341 | __b64_from_24bit (&cp, &buflen, | |
342 | alt_result[12], alt_result[22], alt_result[2], 4); | |
343 | __b64_from_24bit (&cp, &buflen, | |
344 | alt_result[3], alt_result[13], alt_result[23], 4); | |
345 | __b64_from_24bit (&cp, &buflen, | |
346 | alt_result[24], alt_result[4], alt_result[14], 4); | |
347 | __b64_from_24bit (&cp, &buflen, | |
348 | alt_result[15], alt_result[25], alt_result[5], 4); | |
349 | __b64_from_24bit (&cp, &buflen, | |
350 | alt_result[6], alt_result[16], alt_result[26], 4); | |
351 | __b64_from_24bit (&cp, &buflen, | |
352 | alt_result[27], alt_result[7], alt_result[17], 4); | |
353 | __b64_from_24bit (&cp, &buflen, | |
354 | alt_result[18], alt_result[28], alt_result[8], 4); | |
355 | __b64_from_24bit (&cp, &buflen, | |
356 | alt_result[9], alt_result[19], alt_result[29], 4); | |
357 | __b64_from_24bit (&cp, &buflen, | |
358 | 0, alt_result[31], alt_result[30], 3); | |
9425cb9e UD |
359 | if (buflen <= 0) |
360 | { | |
361 | __set_errno (ERANGE); | |
362 | buffer = NULL; | |
363 | } | |
364 | else | |
365 | *cp = '\0'; /* Terminate the string. */ | |
366 | ||
367 | /* Clear the buffer for the intermediate result so that people | |
368 | attaching to processes or reading core dumps cannot get any | |
369 | information. We do it in this way to clear correct_words[] | |
370 | inside the SHA256 implementation as well. */ | |
ff886b82 | 371 | #ifndef USE_NSS |
9425cb9e UD |
372 | __sha256_init_ctx (&ctx); |
373 | __sha256_finish_ctx (&ctx, alt_result); | |
ea1bd74d ZW |
374 | explicit_bzero (&ctx, sizeof (ctx)); |
375 | explicit_bzero (&alt_ctx, sizeof (alt_ctx)); | |
ff886b82 | 376 | #endif |
ea1bd74d ZW |
377 | explicit_bzero (temp_result, sizeof (temp_result)); |
378 | explicit_bzero (p_bytes, key_len); | |
379 | explicit_bzero (s_bytes, salt_len); | |
9425cb9e | 380 | if (copied_key != NULL) |
ea1bd74d | 381 | explicit_bzero (copied_key, key_len); |
9425cb9e | 382 | if (copied_salt != NULL) |
ea1bd74d | 383 | explicit_bzero (copied_salt, salt_len); |
9425cb9e | 384 | |
b8dc394d JL |
385 | free (free_key); |
386 | free (free_pbytes); | |
9425cb9e UD |
387 | return buffer; |
388 | } | |
389 | ||
390 | #ifndef _LIBC | |
391 | # define libc_freeres_ptr(decl) decl | |
392 | #endif | |
393 | libc_freeres_ptr (static char *buffer); | |
394 | ||
395 | /* This entry point is equivalent to the `crypt' function in Unix | |
396 | libcs. */ | |
397 | char * | |
398 | __sha256_crypt (const char *key, const char *salt) | |
399 | { | |
400 | /* We don't want to have an arbitrary limit in the size of the | |
401 | password. We can compute an upper bound for the size of the | |
402 | result in advance and so we can prepare the buffer we pass to | |
403 | `sha256_crypt_r'. */ | |
404 | static int buflen; | |
405 | int needed = (sizeof (sha256_salt_prefix) - 1 | |
406 | + sizeof (sha256_rounds_prefix) + 9 + 1 | |
407 | + strlen (salt) + 1 + 43 + 1); | |
408 | ||
409 | if (buflen < needed) | |
410 | { | |
411 | char *new_buffer = (char *) realloc (buffer, needed); | |
412 | if (new_buffer == NULL) | |
413 | return NULL; | |
414 | ||
415 | buffer = new_buffer; | |
416 | buflen = needed; | |
417 | } | |
418 | ||
419 | return __sha256_crypt_r (key, salt, buffer, buflen); | |
420 | } | |
421 | ||
422 | #ifndef _LIBC | |
423 | static void | |
424 | __attribute__ ((__destructor__)) | |
425 | free_mem (void) | |
426 | { | |
427 | free (buffer); | |
428 | } | |
429 | #endif |