summaryrefslogtreecommitdiff
path: root/server/util/crypto_sha512crypt.c
blob: 9cd03a1e1925b2958b78379f4dccd5b7b5e99682 (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
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
/* This file is based on nss_sha512crypt.c which is based on the work of
 * Ulrich Drepper (http://people.redhat.com/drepper/SHA-crypt.txt).
 *
 * libcrypto is used to provide SHA512 and random number generation.
 * (http://www.openssl.org/docs/crypto/crypto.html).
 *
 *  Sumit Bose <sbose@redhat.com>
 *  George McCollister <georgem@novatech-llc.com>
 */
/* SHA512-based Unix crypt implementation.
   Released into the Public Domain by Ulrich Drepper <drepper@redhat.com>.  */

#define _GNU_SOURCE
#include <endian.h>
#include <errno.h>
#include <limits.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/param.h>
#include <sys/types.h>

#include "util/util.h"

#include <openssl/evp.h>
#include <openssl/rand.h>

/* Define our magic string to mark salt for SHA512 "encryption" replacement. */
const char sha512_salt_prefix[] = "$6$";
#define SALT_PREF_SIZE (sizeof(sha512_salt_prefix) - 1)

/* Prefix for optional rounds specification. */
const char sha512_rounds_prefix[] = "rounds=";
#define ROUNDS_SIZE (sizeof(sha512_rounds_prefix) - 1)

#define SALT_LEN_MAX 16
#define ROUNDS_DEFAULT 5000
#define ROUNDS_MIN 1000
#define ROUNDS_MAX 999999999

/* Table with characters for base64 transformation.  */
const char b64t[64] =
    "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

/* base64 conversion function */
static inline void b64_from_24bit(char **dest, size_t *len, size_t n,
                                  uint8_t b2, uint8_t b1, uint8_t b0)
{
    uint32_t w;
    size_t i;

    if (*len < n) n = *len;

    w = (b2 << 16) | (b1 << 8) | b0;
    for (i = 0; i < n; i++) {
        (*dest)[i] = b64t[w & 0x3f];
        w >>= 6;
    }

    *len -= i;
    *dest += i;
}

#define PTR_2_INT(x) ((x) - ((__typeof__ (x)) NULL))
#define ALIGN64 __alignof__(uint64_t)

static int sha512_crypt_r(const char *key,
                          const char *salt,
                          char *buffer, size_t buflen)
{
    unsigned char temp_result[64] __attribute__((__aligned__(ALIGN64)));
    unsigned char alt_result[64] __attribute__((__aligned__(ALIGN64)));
    size_t rounds = ROUNDS_DEFAULT;
    bool rounds_custom = false;
    EVP_MD_CTX alt_ctx;
    EVP_MD_CTX ctx;
    size_t salt_len;
    size_t key_len;
    size_t cnt;
    char *copied_salt = NULL;
    char *copied_key = NULL;
    char *p_bytes = NULL;
    char *s_bytes = NULL;
    int p1, p2, p3, pt, n;
    unsigned int part;
    char *cp, *tmp;
    int ret;

    /* Find beginning of salt string. The prefix should normally always be
     * present. Just in case it is not. */
    if (strncmp(salt, sha512_salt_prefix, SALT_PREF_SIZE) == 0) {
        /* Skip salt prefix.  */
        salt += SALT_PREF_SIZE;
    }

    if (strncmp(salt, sha512_rounds_prefix, ROUNDS_SIZE) == 0) {
        unsigned long int srounds;
        const char *num;
        char *endp;

        num = salt + ROUNDS_SIZE;
        srounds = strtoul(num, &endp, 10);
        if (*endp == '$') {
            salt = endp + 1;
            if (srounds < ROUNDS_MIN) srounds = ROUNDS_MIN;
            if (srounds > ROUNDS_MAX) srounds = ROUNDS_MAX;
            rounds = srounds;
            rounds_custom = true;
        }
    }

    salt_len = MIN(strcspn(salt, "$"), SALT_LEN_MAX);
    key_len = strlen(key);

    if ((PTR_2_INT(key) % ALIGN64) != 0) {
        tmp = (char *)alloca(key_len + ALIGN64);
        key = copied_key = memcpy(tmp + ALIGN64 - PTR_2_INT(tmp) % ALIGN64, key, key_len);
    }

    if (PTR_2_INT(salt) % ALIGN64 != 0) {
        tmp = (char *)alloca(salt_len + ALIGN64);
        salt = copied_salt = memcpy(tmp + ALIGN64 - PTR_2_INT(tmp) % ALIGN64, salt, salt_len);
    }

    EVP_MD_CTX_init(&ctx);

    EVP_MD_CTX_init(&alt_ctx);

    /* Prepare for the real work.  */
    if (!EVP_DigestInit_ex(&ctx, EVP_sha512(), NULL)) {
        ret = EIO;
        goto done;
    }

    /* Add the key string.  */
    EVP_DigestUpdate(&ctx, (const unsigned char *)key, key_len);

    /* The last part is the salt string. This must be at most 16
     * characters and it ends at the first `$' character (for
     * compatibility with existing implementations). */
    EVP_DigestUpdate(&ctx, (const unsigned char *)salt, salt_len);


    /* Compute alternate SHA512 sum with input KEY, SALT, and KEY.
     * The final result will be added to the first context. */
    if (!EVP_DigestInit_ex(&alt_ctx, EVP_sha512(), NULL)) {
        ret = EIO;
        goto done;
    }

    /* Add key. */
    EVP_DigestUpdate(&alt_ctx, (const unsigned char *)key, key_len);

    /* Add salt. */
    EVP_DigestUpdate(&alt_ctx, (const unsigned char *)salt, salt_len);

    /* Add key again. */
    EVP_DigestUpdate(&alt_ctx, (const unsigned char *)key, key_len);

    /* Now get result of this (64 bytes) and add it to the other context. */
    EVP_DigestFinal_ex(&alt_ctx, alt_result, &part);

    /* Add for any character in the key one byte of the alternate sum. */
    for (cnt = key_len; cnt > 64; cnt -= 64) {
        EVP_DigestUpdate(&ctx, alt_result, 64);
    }
    EVP_DigestUpdate(&ctx, alt_result, cnt);

    /* Take the binary representation of the length of the key and for every
     * 1 add the alternate sum, for every 0 the key. */
    for (cnt = key_len; cnt > 0; cnt >>= 1) {
        if ((cnt & 1) != 0) {
            EVP_DigestUpdate(&ctx, alt_result, 64);
        } else {
            EVP_DigestUpdate(&ctx, (const unsigned char *)key, key_len);
        }
    }

    /* Create intermediate result. */
    EVP_DigestFinal_ex(&ctx, alt_result, &part);

    /* Start computation of P byte sequence. */
    if (!EVP_DigestInit_ex(&alt_ctx, EVP_sha512(), NULL)) {
        ret = EIO;
        goto done;
    }

    /* For every character in the password add the entire password. */
    for (cnt = 0; cnt < key_len; cnt++) {
        EVP_DigestUpdate(&alt_ctx, (const unsigned char *)key, key_len);
    }

    /* Finish the digest. */
    EVP_DigestFinal_ex(&alt_ctx, temp_result, &part);

    /* Create byte sequence P. */
    cp = p_bytes = alloca(key_len);
    for (cnt = key_len; cnt >= 64; cnt -= 64) {
        cp = mempcpy(cp, temp_result, 64);
    }
    memcpy(cp, temp_result, cnt);

    /* Start computation of S byte sequence. */
    if (!EVP_DigestInit_ex(&alt_ctx, EVP_sha512(), NULL)) {
        ret = EIO;
        goto done;
    }

    /* For every character in the password add the entire salt. */
    for (cnt = 0; cnt < 16 + alt_result[0]; cnt++) {
        EVP_DigestUpdate(&alt_ctx, (const unsigned char *)salt, salt_len);
    }

    /* Finish the digest. */
    EVP_DigestFinal_ex(&alt_ctx, temp_result, &part);

    /* Create byte sequence S.  */
    cp = s_bytes = alloca(salt_len);
    for (cnt = salt_len; cnt >= 64; cnt -= 64) {
        cp = mempcpy(cp, temp_result, 64);
    }
    memcpy(cp, temp_result, cnt);

    /* Repeatedly run the collected hash value through SHA512 to burn CPU cycles. */
    for (cnt = 0; cnt < rounds; cnt++) {

        if (!EVP_DigestInit_ex(&ctx, EVP_sha512(), NULL)) {
            ret = EIO;
            goto done;
        }

        /* Add key or last result. */
        if ((cnt & 1) != 0) {
            EVP_DigestUpdate(&ctx, (const unsigned char *)p_bytes, key_len);
        } else {
            EVP_DigestUpdate(&ctx, alt_result, 64);
        }

        /* Add salt for numbers not divisible by 3. */
        if (cnt % 3 != 0) {
            EVP_DigestUpdate(&ctx, (const unsigned char *)s_bytes, salt_len);
        }

        /* Add key for numbers not divisible by 7. */
        if (cnt % 7 != 0) {
            EVP_DigestUpdate(&ctx, (const unsigned char *)p_bytes, key_len);
        }

        /* Add key or last result. */
        if ((cnt & 1) != 0) {
            EVP_DigestUpdate(&ctx, alt_result, 64);
        } else {
            EVP_DigestUpdate(&ctx, (const unsigned char *)p_bytes, key_len);
        }

        /* Create intermediate result. */
        EVP_DigestFinal_ex(&ctx, alt_result, &part);
    }

    /* Now we can construct the result string.
     * It consists of three parts. */
    if (buflen <= SALT_PREF_SIZE) {
        ret = ERANGE;
        goto done;
    }

    cp = __stpncpy(buffer, sha512_salt_prefix, SALT_PREF_SIZE);
    buflen -= SALT_PREF_SIZE;

    if (rounds_custom) {
        n = snprintf(cp, buflen, "%s%zu$",
                     sha512_rounds_prefix, rounds);
        if (n < 0 || n >= buflen) {
            ret = ERANGE;
            goto done;
        }
        cp += n;
        buflen -= n;
    }

    if (buflen <= salt_len + 1) {
        ret = ERANGE;
        goto done;
    }
    cp = __stpncpy(cp, salt, salt_len);
    *cp++ = '$';
    buflen -= salt_len + 1;

    /* fuzzyfill the base 64 string */
    p1 = 0;
    p2 = 21;
    p3 = 42;
    for (n = 0; n < 21; n++) {
        b64_from_24bit(&cp, &buflen, 4, alt_result[p1], alt_result[p2], alt_result[p3]);
        if (buflen == 0) {
            ret = ERANGE;
            goto done;
        }
        pt = p1;
        p1 = p2 + 1;
        p2 = p3 + 1;
        p3 = pt + 1;
    }
    /* 64th and last byte */
    b64_from_24bit(&cp, &buflen, 2, 0, 0, alt_result[p3]);
    if (buflen == 0) {
        ret = ERANGE;
        goto done;
    }

    *cp = '\0';
    ret = EOK;

done:
    /* Clear the buffer for the intermediate result so that people attaching
     * to processes or reading core dumps cannot get any information. We do it
     * in this way to clear correct_words[] inside the SHA512 implementation
     * as well.  */
    EVP_MD_CTX_cleanup(&ctx);
    EVP_MD_CTX_cleanup(&alt_ctx);
    if (p_bytes) memset(p_bytes, '\0', key_len);
    if (s_bytes) memset(s_bytes, '\0', salt_len);
    if (copied_key) memset(copied_key, '\0', key_len);
    if (copied_salt) memset(copied_salt, '\0', salt_len);
    memset(temp_result, '\0', sizeof(temp_result));

    return ret;
}

int s3crypt_sha512(TALLOC_CTX *memctx,
                   const char *key, const char *salt, char **_hash)
{
    char *hash;
    int hlen = (sizeof (sha512_salt_prefix) - 1
                + sizeof (sha512_rounds_prefix) + 9 + 1
                + strlen (salt) + 1 + 86 + 1);
    int ret;

    hash = talloc_size(memctx, hlen);
    if (!hash) return ENOMEM;

    ret = sha512_crypt_r(key, salt, hash, hlen);
    if (ret) return ret;

    *_hash = hash;
    return ret;
}

#define SALT_RAND_LEN 12

int s3crypt_gen_salt(TALLOC_CTX *memctx, char **_salt)
{
    uint8_t rb[SALT_RAND_LEN];
    char *salt, *cp;
    size_t slen;
    int ret;

    salt = talloc_size(memctx, SALT_LEN_MAX + 1);
    if (!salt) {
        return ENOMEM;
    }

    ret = RAND_bytes(rb, SALT_RAND_LEN);
    if (ret == 0) {
        return EIO;
    }

    slen = SALT_LEN_MAX;
    cp = salt;
    b64_from_24bit(&cp, &slen, 4, rb[0], rb[1], rb[2]);
    b64_from_24bit(&cp, &slen, 4, rb[3], rb[4], rb[5]);
    b64_from_24bit(&cp, &slen, 4, rb[6], rb[7], rb[8]);
    b64_from_24bit(&cp, &slen, 4, rb[9], rb[10], rb[11]);
    *cp = '\0';

    *_salt = salt;

    return EOK;
}