lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame^] | 1 | /* One way encryption based on MD5 sum. |
| 2 | Compatible with the behavior of MD5 crypt introduced in FreeBSD 2.0. |
| 3 | Copyright (C) 1996-2015 Free Software Foundation, Inc. |
| 4 | This file is part of the GNU C Library. |
| 5 | Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996. |
| 6 | |
| 7 | The GNU C Library is free software; you can redistribute it and/or |
| 8 | modify it under the terms of the GNU Lesser General Public |
| 9 | License as published by the Free Software Foundation; either |
| 10 | version 2.1 of the License, or (at your option) any later version. |
| 11 | |
| 12 | The GNU C Library is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 15 | Lesser General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU Lesser General Public |
| 18 | License along with the GNU C Library; if not, see |
| 19 | <http://www.gnu.org/licenses/>. */ |
| 20 | |
| 21 | #include <assert.h> |
| 22 | #include <errno.h> |
| 23 | #include <stdlib.h> |
| 24 | #include <string.h> |
| 25 | #include <sys/param.h> |
| 26 | |
| 27 | #include "md5.h" |
| 28 | #include "crypt-private.h" |
| 29 | |
| 30 | |
| 31 | #ifdef USE_NSS |
| 32 | typedef int PRBool; |
| 33 | # include <hasht.h> |
| 34 | # include <nsslowhash.h> |
| 35 | |
| 36 | # define md5_init_ctx(ctxp, nss_ctxp) \ |
| 37 | do \ |
| 38 | { \ |
| 39 | if (((nss_ctxp = NSSLOWHASH_NewContext (nss_ictx, HASH_AlgMD5)) \ |
| 40 | == NULL)) \ |
| 41 | { \ |
| 42 | if (nss_ctx != NULL) \ |
| 43 | NSSLOWHASH_Destroy (nss_ctx); \ |
| 44 | if (nss_alt_ctx != NULL) \ |
| 45 | NSSLOWHASH_Destroy (nss_alt_ctx); \ |
| 46 | return NULL; \ |
| 47 | } \ |
| 48 | NSSLOWHASH_Begin (nss_ctxp); \ |
| 49 | } \ |
| 50 | while (0) |
| 51 | |
| 52 | # define md5_process_bytes(buf, len, ctxp, nss_ctxp) \ |
| 53 | NSSLOWHASH_Update (nss_ctxp, (const unsigned char *) buf, len) |
| 54 | |
| 55 | # define md5_finish_ctx(ctxp, nss_ctxp, result) \ |
| 56 | do \ |
| 57 | { \ |
| 58 | unsigned int ret; \ |
| 59 | NSSLOWHASH_End (nss_ctxp, result, &ret, sizeof (result)); \ |
| 60 | assert (ret == sizeof (result)); \ |
| 61 | NSSLOWHASH_Destroy (nss_ctxp); \ |
| 62 | nss_ctxp = NULL; \ |
| 63 | } \ |
| 64 | while (0) |
| 65 | #else |
| 66 | # define md5_init_ctx(ctxp, nss_ctxp) \ |
| 67 | __md5_init_ctx (ctxp) |
| 68 | |
| 69 | # define md5_process_bytes(buf, len, ctxp, nss_ctxp) \ |
| 70 | __md5_process_bytes(buf, len, ctxp) |
| 71 | |
| 72 | # define md5_finish_ctx(ctxp, nss_ctxp, result) \ |
| 73 | __md5_finish_ctx (ctxp, result) |
| 74 | #endif |
| 75 | |
| 76 | |
| 77 | /* Define our magic string to mark salt for MD5 "encryption" |
| 78 | replacement. This is meant to be the same as for other MD5 based |
| 79 | encryption implementations. */ |
| 80 | static const char md5_salt_prefix[] = "$1$"; |
| 81 | |
| 82 | |
| 83 | /* Prototypes for local functions. */ |
| 84 | extern char *__md5_crypt_r (const char *key, const char *salt, |
| 85 | char *buffer, int buflen); |
| 86 | extern char *__md5_crypt (const char *key, const char *salt); |
| 87 | |
| 88 | |
| 89 | /* This entry point is equivalent to the `crypt' function in Unix |
| 90 | libcs. */ |
| 91 | char * |
| 92 | __md5_crypt_r (key, salt, buffer, buflen) |
| 93 | const char *key; |
| 94 | const char *salt; |
| 95 | char *buffer; |
| 96 | int buflen; |
| 97 | { |
| 98 | unsigned char alt_result[16] |
| 99 | __attribute__ ((__aligned__ (__alignof__ (md5_uint32)))); |
| 100 | size_t salt_len; |
| 101 | size_t key_len; |
| 102 | size_t cnt; |
| 103 | char *cp; |
| 104 | char *copied_key = NULL; |
| 105 | char *copied_salt = NULL; |
| 106 | char *free_key = NULL; |
| 107 | size_t alloca_used = 0; |
| 108 | |
| 109 | /* Find beginning of salt string. The prefix should normally always |
| 110 | be present. Just in case it is not. */ |
| 111 | if (strncmp (md5_salt_prefix, salt, sizeof (md5_salt_prefix) - 1) == 0) |
| 112 | /* Skip salt prefix. */ |
| 113 | salt += sizeof (md5_salt_prefix) - 1; |
| 114 | |
| 115 | salt_len = MIN (strcspn (salt, "$"), 8); |
| 116 | key_len = strlen (key); |
| 117 | |
| 118 | if ((key - (char *) 0) % __alignof__ (md5_uint32) != 0) |
| 119 | { |
| 120 | char *tmp; |
| 121 | |
| 122 | if (__libc_use_alloca (alloca_used + key_len + __alignof__ (md5_uint32))) |
| 123 | tmp = (char *) alloca (key_len + __alignof__ (md5_uint32)); |
| 124 | else |
| 125 | { |
| 126 | free_key = tmp = (char *) malloc (key_len + __alignof__ (md5_uint32)); |
| 127 | if (tmp == NULL) |
| 128 | return NULL; |
| 129 | } |
| 130 | |
| 131 | key = copied_key = |
| 132 | memcpy (tmp + __alignof__ (md5_uint32) |
| 133 | - (tmp - (char *) 0) % __alignof__ (md5_uint32), |
| 134 | key, key_len); |
| 135 | assert ((key - (char *) 0) % __alignof__ (md5_uint32) == 0); |
| 136 | } |
| 137 | |
| 138 | if ((salt - (char *) 0) % __alignof__ (md5_uint32) != 0) |
| 139 | { |
| 140 | char *tmp = (char *) alloca (salt_len + __alignof__ (md5_uint32)); |
| 141 | salt = copied_salt = |
| 142 | memcpy (tmp + __alignof__ (md5_uint32) |
| 143 | - (tmp - (char *) 0) % __alignof__ (md5_uint32), |
| 144 | salt, salt_len); |
| 145 | assert ((salt - (char *) 0) % __alignof__ (md5_uint32) == 0); |
| 146 | } |
| 147 | |
| 148 | #ifdef USE_NSS |
| 149 | /* Initialize libfreebl3. */ |
| 150 | NSSLOWInitContext *nss_ictx = NSSLOW_Init (); |
| 151 | if (nss_ictx == NULL) |
| 152 | { |
| 153 | free (free_key); |
| 154 | return NULL; |
| 155 | } |
| 156 | NSSLOWHASHContext *nss_ctx = NULL; |
| 157 | NSSLOWHASHContext *nss_alt_ctx = NULL; |
| 158 | #else |
| 159 | struct md5_ctx ctx; |
| 160 | struct md5_ctx alt_ctx; |
| 161 | #endif |
| 162 | |
| 163 | /* Prepare for the real work. */ |
| 164 | md5_init_ctx (&ctx, nss_ctx); |
| 165 | |
| 166 | /* Add the key string. */ |
| 167 | md5_process_bytes (key, key_len, &ctx, nss_ctx); |
| 168 | |
| 169 | /* Because the SALT argument need not always have the salt prefix we |
| 170 | add it separately. */ |
| 171 | md5_process_bytes (md5_salt_prefix, sizeof (md5_salt_prefix) - 1, |
| 172 | &ctx, nss_ctx); |
| 173 | |
| 174 | /* The last part is the salt string. This must be at most 8 |
| 175 | characters and it ends at the first `$' character (for |
| 176 | compatibility with existing implementations). */ |
| 177 | md5_process_bytes (salt, salt_len, &ctx, nss_ctx); |
| 178 | |
| 179 | |
| 180 | /* Compute alternate MD5 sum with input KEY, SALT, and KEY. The |
| 181 | final result will be added to the first context. */ |
| 182 | md5_init_ctx (&alt_ctx, nss_alt_ctx); |
| 183 | |
| 184 | /* Add key. */ |
| 185 | md5_process_bytes (key, key_len, &alt_ctx, nss_alt_ctx); |
| 186 | |
| 187 | /* Add salt. */ |
| 188 | md5_process_bytes (salt, salt_len, &alt_ctx, nss_alt_ctx); |
| 189 | |
| 190 | /* Add key again. */ |
| 191 | md5_process_bytes (key, key_len, &alt_ctx, nss_alt_ctx); |
| 192 | |
| 193 | /* Now get result of this (16 bytes) and add it to the other |
| 194 | context. */ |
| 195 | md5_finish_ctx (&alt_ctx, nss_alt_ctx, alt_result); |
| 196 | |
| 197 | /* Add for any character in the key one byte of the alternate sum. */ |
| 198 | for (cnt = key_len; cnt > 16; cnt -= 16) |
| 199 | md5_process_bytes (alt_result, 16, &ctx, nss_ctx); |
| 200 | md5_process_bytes (alt_result, cnt, &ctx, nss_ctx); |
| 201 | |
| 202 | /* For the following code we need a NUL byte. */ |
| 203 | *alt_result = '\0'; |
| 204 | |
| 205 | /* The original implementation now does something weird: for every 1 |
| 206 | bit in the key the first 0 is added to the buffer, for every 0 |
| 207 | bit the first character of the key. This does not seem to be |
| 208 | what was intended but we have to follow this to be compatible. */ |
| 209 | for (cnt = key_len; cnt > 0; cnt >>= 1) |
| 210 | md5_process_bytes ((cnt & 1) != 0 |
| 211 | ? (const void *) alt_result : (const void *) key, 1, |
| 212 | &ctx, nss_ctx); |
| 213 | |
| 214 | /* Create intermediate result. */ |
| 215 | md5_finish_ctx (&ctx, nss_ctx, alt_result); |
| 216 | |
| 217 | /* Now comes another weirdness. In fear of password crackers here |
| 218 | comes a quite long loop which just processes the output of the |
| 219 | previous round again. We cannot ignore this here. */ |
| 220 | for (cnt = 0; cnt < 1000; ++cnt) |
| 221 | { |
| 222 | /* New context. */ |
| 223 | md5_init_ctx (&ctx, nss_ctx); |
| 224 | |
| 225 | /* Add key or last result. */ |
| 226 | if ((cnt & 1) != 0) |
| 227 | md5_process_bytes (key, key_len, &ctx, nss_ctx); |
| 228 | else |
| 229 | md5_process_bytes (alt_result, 16, &ctx, nss_ctx); |
| 230 | |
| 231 | /* Add salt for numbers not divisible by 3. */ |
| 232 | if (cnt % 3 != 0) |
| 233 | md5_process_bytes (salt, salt_len, &ctx, nss_ctx); |
| 234 | |
| 235 | /* Add key for numbers not divisible by 7. */ |
| 236 | if (cnt % 7 != 0) |
| 237 | md5_process_bytes (key, key_len, &ctx, nss_ctx); |
| 238 | |
| 239 | /* Add key or last result. */ |
| 240 | if ((cnt & 1) != 0) |
| 241 | md5_process_bytes (alt_result, 16, &ctx, nss_ctx); |
| 242 | else |
| 243 | md5_process_bytes (key, key_len, &ctx, nss_ctx); |
| 244 | |
| 245 | /* Create intermediate result. */ |
| 246 | md5_finish_ctx (&ctx, nss_ctx, alt_result); |
| 247 | } |
| 248 | |
| 249 | #ifdef USE_NSS |
| 250 | /* Free libfreebl3 resources. */ |
| 251 | NSSLOW_Shutdown (nss_ictx); |
| 252 | #endif |
| 253 | |
| 254 | /* Now we can construct the result string. It consists of three |
| 255 | parts. */ |
| 256 | cp = __stpncpy (buffer, md5_salt_prefix, MAX (0, buflen)); |
| 257 | buflen -= sizeof (md5_salt_prefix) - 1; |
| 258 | |
| 259 | cp = __stpncpy (cp, salt, MIN ((size_t) MAX (0, buflen), salt_len)); |
| 260 | buflen -= MIN ((size_t) MAX (0, buflen), salt_len); |
| 261 | |
| 262 | if (buflen > 0) |
| 263 | { |
| 264 | *cp++ = '$'; |
| 265 | --buflen; |
| 266 | } |
| 267 | |
| 268 | __b64_from_24bit (&cp, &buflen, |
| 269 | alt_result[0], alt_result[6], alt_result[12], 4); |
| 270 | __b64_from_24bit (&cp, &buflen, |
| 271 | alt_result[1], alt_result[7], alt_result[13], 4); |
| 272 | __b64_from_24bit (&cp, &buflen, |
| 273 | alt_result[2], alt_result[8], alt_result[14], 4); |
| 274 | __b64_from_24bit (&cp, &buflen, |
| 275 | alt_result[3], alt_result[9], alt_result[15], 4); |
| 276 | __b64_from_24bit (&cp, &buflen, |
| 277 | alt_result[4], alt_result[10], alt_result[5], 4); |
| 278 | __b64_from_24bit (&cp, &buflen, |
| 279 | 0, 0, alt_result[11], 2); |
| 280 | if (buflen <= 0) |
| 281 | { |
| 282 | __set_errno (ERANGE); |
| 283 | buffer = NULL; |
| 284 | } |
| 285 | else |
| 286 | *cp = '\0'; /* Terminate the string. */ |
| 287 | |
| 288 | /* Clear the buffer for the intermediate result so that people |
| 289 | attaching to processes or reading core dumps cannot get any |
| 290 | information. We do it in this way to clear correct_words[] |
| 291 | inside the MD5 implementation as well. */ |
| 292 | #ifndef USE_NSS |
| 293 | __md5_init_ctx (&ctx); |
| 294 | __md5_finish_ctx (&ctx, alt_result); |
| 295 | memset (&ctx, '\0', sizeof (ctx)); |
| 296 | memset (&alt_ctx, '\0', sizeof (alt_ctx)); |
| 297 | #endif |
| 298 | if (copied_key != NULL) |
| 299 | memset (copied_key, '\0', key_len); |
| 300 | if (copied_salt != NULL) |
| 301 | memset (copied_salt, '\0', salt_len); |
| 302 | |
| 303 | free (free_key); |
| 304 | return buffer; |
| 305 | } |
| 306 | |
| 307 | #ifndef _LIBC |
| 308 | # define libc_freeres_ptr(decl) decl |
| 309 | #endif |
| 310 | libc_freeres_ptr (static char *buffer); |
| 311 | |
| 312 | char * |
| 313 | __md5_crypt (const char *key, const char *salt) |
| 314 | { |
| 315 | /* We don't want to have an arbitrary limit in the size of the |
| 316 | password. We can compute the size of the result in advance and |
| 317 | so we can prepare the buffer we pass to `md5_crypt_r'. */ |
| 318 | static int buflen; |
| 319 | int needed = 3 + strlen (salt) + 1 + 26 + 1; |
| 320 | |
| 321 | if (buflen < needed) |
| 322 | { |
| 323 | char *new_buffer = (char *) realloc (buffer, needed); |
| 324 | if (new_buffer == NULL) |
| 325 | return NULL; |
| 326 | |
| 327 | buffer = new_buffer; |
| 328 | buflen = needed; |
| 329 | } |
| 330 | |
| 331 | return __md5_crypt_r (key, salt, buffer, buflen); |
| 332 | } |
| 333 | |
| 334 | #ifndef _LIBC |
| 335 | static void |
| 336 | __attribute__ ((__destructor__)) |
| 337 | free_mem (void) |
| 338 | { |
| 339 | free (buffer); |
| 340 | } |
| 341 | #endif |