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Commit | Line | Data |
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8efc0c15 | 1 | /* |
5260325f | 2 | * |
3 | * authfile.c | |
4 | * | |
5 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
6 | * | |
7 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
8 | * All rights reserved | |
9 | * | |
10 | * Created: Mon Mar 27 03:52:05 1995 ylo | |
11 | * | |
12 | * This file contains functions for reading and writing identity files, and | |
13 | * for reading the passphrase from the user. | |
14 | * | |
15 | */ | |
8efc0c15 | 16 | |
17 | #include "includes.h" | |
18 | RCSID("$Id$"); | |
19 | ||
5881cd60 | 20 | #ifdef HAVE_OPENSSL |
8efc0c15 | 21 | #include <openssl/bn.h> |
5881cd60 | 22 | #endif |
23 | #ifdef HAVE_SSL | |
24 | #include <ssl/bn.h> | |
25 | #endif | |
26 | ||
8efc0c15 | 27 | #include "xmalloc.h" |
28 | #include "buffer.h" | |
29 | #include "bufaux.h" | |
30 | #include "cipher.h" | |
31 | #include "ssh.h" | |
32 | ||
33 | /* Version identification string for identity files. */ | |
34 | #define AUTHFILE_ID_STRING "SSH PRIVATE KEY FILE FORMAT 1.1\n" | |
35 | ||
aa3378df | 36 | /* |
37 | * Saves the authentication (private) key in a file, encrypting it with | |
38 | * passphrase. The identification of the file (lowest 64 bits of n) will | |
39 | * precede the key to provide identification of the key without needing a | |
40 | * passphrase. | |
41 | */ | |
8efc0c15 | 42 | |
43 | int | |
44 | save_private_key(const char *filename, const char *passphrase, | |
45 | RSA *key, const char *comment) | |
46 | { | |
5260325f | 47 | Buffer buffer, encrypted; |
48 | char buf[100], *cp; | |
a408af76 | 49 | int fd, i; |
5260325f | 50 | CipherContext cipher; |
51 | int cipher_type; | |
52 | u_int32_t rand; | |
53 | ||
aa3378df | 54 | /* |
55 | * If the passphrase is empty, use SSH_CIPHER_NONE to ease converting | |
56 | * to another cipher; otherwise use SSH_AUTHFILE_CIPHER. | |
57 | */ | |
5260325f | 58 | if (strcmp(passphrase, "") == 0) |
59 | cipher_type = SSH_CIPHER_NONE; | |
60 | else | |
61 | cipher_type = SSH_AUTHFILE_CIPHER; | |
62 | ||
63 | /* This buffer is used to built the secret part of the private key. */ | |
64 | buffer_init(&buffer); | |
65 | ||
66 | /* Put checkbytes for checking passphrase validity. */ | |
67 | rand = arc4random(); | |
68 | buf[0] = rand & 0xff; | |
69 | buf[1] = (rand >> 8) & 0xff; | |
70 | buf[2] = buf[0]; | |
71 | buf[3] = buf[1]; | |
72 | buffer_append(&buffer, buf, 4); | |
73 | ||
aa3378df | 74 | /* |
75 | * Store the private key (n and e will not be stored because they | |
76 | * will be stored in plain text, and storing them also in encrypted | |
77 | * format would just give known plaintext). | |
78 | */ | |
5260325f | 79 | buffer_put_bignum(&buffer, key->d); |
80 | buffer_put_bignum(&buffer, key->iqmp); | |
81 | buffer_put_bignum(&buffer, key->q); /* reverse from SSL p */ | |
82 | buffer_put_bignum(&buffer, key->p); /* reverse from SSL q */ | |
83 | ||
84 | /* Pad the part to be encrypted until its size is a multiple of 8. */ | |
85 | while (buffer_len(&buffer) % 8 != 0) | |
86 | buffer_put_char(&buffer, 0); | |
87 | ||
88 | /* This buffer will be used to contain the data in the file. */ | |
89 | buffer_init(&encrypted); | |
90 | ||
91 | /* First store keyfile id string. */ | |
92 | cp = AUTHFILE_ID_STRING; | |
93 | for (i = 0; cp[i]; i++) | |
94 | buffer_put_char(&encrypted, cp[i]); | |
95 | buffer_put_char(&encrypted, 0); | |
96 | ||
97 | /* Store cipher type. */ | |
98 | buffer_put_char(&encrypted, cipher_type); | |
99 | buffer_put_int(&encrypted, 0); /* For future extension */ | |
100 | ||
101 | /* Store public key. This will be in plain text. */ | |
102 | buffer_put_int(&encrypted, BN_num_bits(key->n)); | |
103 | buffer_put_bignum(&encrypted, key->n); | |
104 | buffer_put_bignum(&encrypted, key->e); | |
105 | buffer_put_string(&encrypted, comment, strlen(comment)); | |
106 | ||
107 | /* Allocate space for the private part of the key in the buffer. */ | |
108 | buffer_append_space(&encrypted, &cp, buffer_len(&buffer)); | |
109 | ||
110 | cipher_set_key_string(&cipher, cipher_type, passphrase, 1); | |
111 | cipher_encrypt(&cipher, (unsigned char *) cp, | |
112 | (unsigned char *) buffer_ptr(&buffer), | |
113 | buffer_len(&buffer)); | |
114 | memset(&cipher, 0, sizeof(cipher)); | |
115 | ||
116 | /* Destroy temporary data. */ | |
117 | memset(buf, 0, sizeof(buf)); | |
118 | buffer_free(&buffer); | |
119 | ||
a408af76 | 120 | fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600); |
121 | if (fd < 0) | |
5260325f | 122 | return 0; |
a408af76 | 123 | if (write(fd, buffer_ptr(&encrypted), buffer_len(&encrypted)) != |
5260325f | 124 | buffer_len(&encrypted)) { |
125 | debug("Write to key file %.200s failed: %.100s", filename, | |
126 | strerror(errno)); | |
127 | buffer_free(&encrypted); | |
a408af76 | 128 | close(fd); |
5260325f | 129 | remove(filename); |
130 | return 0; | |
131 | } | |
a408af76 | 132 | close(fd); |
5260325f | 133 | buffer_free(&encrypted); |
134 | return 1; | |
8efc0c15 | 135 | } |
136 | ||
aa3378df | 137 | /* |
138 | * Loads the public part of the key file. Returns 0 if an error was | |
139 | * encountered (the file does not exist or is not readable), and non-zero | |
140 | * otherwise. | |
141 | */ | |
8efc0c15 | 142 | |
143 | int | |
5260325f | 144 | load_public_key(const char *filename, RSA * pub, |
8efc0c15 | 145 | char **comment_return) |
146 | { | |
a408af76 | 147 | int fd, i; |
5260325f | 148 | off_t len; |
149 | Buffer buffer; | |
150 | char *cp; | |
151 | ||
a408af76 | 152 | fd = open(filename, O_RDONLY); |
153 | if (fd < 0) | |
5260325f | 154 | return 0; |
a408af76 | 155 | len = lseek(fd, (off_t) 0, SEEK_END); |
156 | lseek(fd, (off_t) 0, SEEK_SET); | |
5260325f | 157 | |
158 | buffer_init(&buffer); | |
159 | buffer_append_space(&buffer, &cp, len); | |
160 | ||
a408af76 | 161 | if (read(fd, cp, (size_t) len) != (size_t) len) { |
5260325f | 162 | debug("Read from key file %.200s failed: %.100s", filename, |
163 | strerror(errno)); | |
164 | buffer_free(&buffer); | |
a408af76 | 165 | close(fd); |
5260325f | 166 | return 0; |
167 | } | |
a408af76 | 168 | close(fd); |
5260325f | 169 | |
170 | /* Check that it is at least big enought to contain the ID string. */ | |
171 | if (len < strlen(AUTHFILE_ID_STRING) + 1) { | |
172 | debug("Bad key file %.200s.", filename); | |
173 | buffer_free(&buffer); | |
174 | return 0; | |
175 | } | |
aa3378df | 176 | /* |
177 | * Make sure it begins with the id string. Consume the id string | |
178 | * from the buffer. | |
179 | */ | |
5260325f | 180 | for (i = 0; i < (unsigned int) strlen(AUTHFILE_ID_STRING) + 1; i++) |
a408af76 | 181 | if (buffer_get_char(&buffer) != (u_char) AUTHFILE_ID_STRING[i]) { |
5260325f | 182 | debug("Bad key file %.200s.", filename); |
183 | buffer_free(&buffer); | |
184 | return 0; | |
185 | } | |
186 | /* Skip cipher type and reserved data. */ | |
187 | (void) buffer_get_char(&buffer); /* cipher type */ | |
188 | (void) buffer_get_int(&buffer); /* reserved */ | |
189 | ||
190 | /* Read the public key from the buffer. */ | |
191 | buffer_get_int(&buffer); | |
192 | pub->n = BN_new(); | |
193 | buffer_get_bignum(&buffer, pub->n); | |
194 | pub->e = BN_new(); | |
195 | buffer_get_bignum(&buffer, pub->e); | |
196 | if (comment_return) | |
197 | *comment_return = buffer_get_string(&buffer, NULL); | |
198 | /* The encrypted private part is not parsed by this function. */ | |
199 | ||
8efc0c15 | 200 | buffer_free(&buffer); |
5260325f | 201 | |
202 | return 1; | |
8efc0c15 | 203 | } |
204 | ||
aa3378df | 205 | /* |
206 | * Loads the private key from the file. Returns 0 if an error is encountered | |
207 | * (file does not exist or is not readable, or passphrase is bad). This | |
208 | * initializes the private key. | |
209 | * Assumes we are called under uid of the owner of the file. | |
210 | */ | |
8efc0c15 | 211 | |
212 | int | |
213 | load_private_key(const char *filename, const char *passphrase, | |
5260325f | 214 | RSA * prv, char **comment_return) |
8efc0c15 | 215 | { |
a408af76 | 216 | int fd, i, check1, check2, cipher_type; |
5260325f | 217 | off_t len; |
218 | Buffer buffer, decrypted; | |
219 | char *cp; | |
220 | CipherContext cipher; | |
221 | BN_CTX *ctx; | |
222 | BIGNUM *aux; | |
223 | struct stat st; | |
224 | ||
a408af76 | 225 | fd = open(filename, O_RDONLY); |
226 | if (fd < 0) | |
5260325f | 227 | return 0; |
228 | ||
aa3378df | 229 | /* check owner and modes */ |
a408af76 | 230 | if (fstat(fd, &st) < 0 || |
5260325f | 231 | (st.st_uid != 0 && st.st_uid != getuid()) || |
232 | (st.st_mode & 077) != 0) { | |
a408af76 | 233 | close(fd); |
5260325f | 234 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
235 | error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @"); | |
236 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
237 | error("Bad ownership or mode(0%3.3o) for '%s'.", | |
238 | st.st_mode & 0777, filename); | |
239 | error("It is recommended that your private key files are NOT accessible by others."); | |
240 | return 0; | |
241 | } | |
a408af76 | 242 | len = lseek(fd, (off_t) 0, SEEK_END); |
243 | lseek(fd, (off_t) 0, SEEK_SET); | |
5260325f | 244 | |
245 | buffer_init(&buffer); | |
246 | buffer_append_space(&buffer, &cp, len); | |
247 | ||
a408af76 | 248 | if (read(fd, cp, (size_t) len) != (size_t) len) { |
5260325f | 249 | debug("Read from key file %.200s failed: %.100s", filename, |
250 | strerror(errno)); | |
251 | buffer_free(&buffer); | |
a408af76 | 252 | close(fd); |
5260325f | 253 | return 0; |
254 | } | |
a408af76 | 255 | close(fd); |
5260325f | 256 | |
257 | /* Check that it is at least big enought to contain the ID string. */ | |
258 | if (len < strlen(AUTHFILE_ID_STRING) + 1) { | |
259 | debug("Bad key file %.200s.", filename); | |
260 | buffer_free(&buffer); | |
261 | return 0; | |
262 | } | |
aa3378df | 263 | /* |
264 | * Make sure it begins with the id string. Consume the id string | |
265 | * from the buffer. | |
266 | */ | |
5260325f | 267 | for (i = 0; i < (unsigned int) strlen(AUTHFILE_ID_STRING) + 1; i++) |
268 | if (buffer_get_char(&buffer) != (unsigned char) AUTHFILE_ID_STRING[i]) { | |
269 | debug("Bad key file %.200s.", filename); | |
270 | buffer_free(&buffer); | |
271 | return 0; | |
272 | } | |
273 | /* Read cipher type. */ | |
274 | cipher_type = buffer_get_char(&buffer); | |
275 | (void) buffer_get_int(&buffer); /* Reserved data. */ | |
276 | ||
277 | /* Read the public key from the buffer. */ | |
278 | buffer_get_int(&buffer); | |
279 | prv->n = BN_new(); | |
280 | buffer_get_bignum(&buffer, prv->n); | |
281 | prv->e = BN_new(); | |
282 | buffer_get_bignum(&buffer, prv->e); | |
283 | if (comment_return) | |
284 | *comment_return = buffer_get_string(&buffer, NULL); | |
285 | else | |
286 | xfree(buffer_get_string(&buffer, NULL)); | |
287 | ||
288 | /* Check that it is a supported cipher. */ | |
289 | if (((cipher_mask() | SSH_CIPHER_NONE | SSH_AUTHFILE_CIPHER) & | |
290 | (1 << cipher_type)) == 0) { | |
291 | debug("Unsupported cipher %.100s used in key file %.200s.", | |
292 | cipher_name(cipher_type), filename); | |
293 | buffer_free(&buffer); | |
294 | goto fail; | |
295 | } | |
296 | /* Initialize space for decrypted data. */ | |
297 | buffer_init(&decrypted); | |
298 | buffer_append_space(&decrypted, &cp, buffer_len(&buffer)); | |
299 | ||
300 | /* Rest of the buffer is encrypted. Decrypt it using the passphrase. */ | |
301 | cipher_set_key_string(&cipher, cipher_type, passphrase, 0); | |
302 | cipher_decrypt(&cipher, (unsigned char *) cp, | |
303 | (unsigned char *) buffer_ptr(&buffer), | |
304 | buffer_len(&buffer)); | |
305 | ||
8efc0c15 | 306 | buffer_free(&buffer); |
5260325f | 307 | |
308 | check1 = buffer_get_char(&decrypted); | |
309 | check2 = buffer_get_char(&decrypted); | |
310 | if (check1 != buffer_get_char(&decrypted) || | |
311 | check2 != buffer_get_char(&decrypted)) { | |
312 | if (strcmp(passphrase, "") != 0) | |
313 | debug("Bad passphrase supplied for key file %.200s.", filename); | |
314 | /* Bad passphrase. */ | |
315 | buffer_free(&decrypted); | |
316 | fail: | |
317 | BN_clear_free(prv->n); | |
318 | BN_clear_free(prv->e); | |
319 | if (comment_return) | |
320 | xfree(*comment_return); | |
321 | return 0; | |
322 | } | |
323 | /* Read the rest of the private key. */ | |
324 | prv->d = BN_new(); | |
325 | buffer_get_bignum(&decrypted, prv->d); | |
326 | prv->iqmp = BN_new(); | |
327 | buffer_get_bignum(&decrypted, prv->iqmp); /* u */ | |
328 | /* in SSL and SSH p and q are exchanged */ | |
329 | prv->q = BN_new(); | |
330 | buffer_get_bignum(&decrypted, prv->q); /* p */ | |
331 | prv->p = BN_new(); | |
332 | buffer_get_bignum(&decrypted, prv->p); /* q */ | |
333 | ||
334 | ctx = BN_CTX_new(); | |
335 | aux = BN_new(); | |
336 | ||
337 | BN_sub(aux, prv->q, BN_value_one()); | |
338 | prv->dmq1 = BN_new(); | |
339 | BN_mod(prv->dmq1, prv->d, aux, ctx); | |
340 | ||
341 | BN_sub(aux, prv->p, BN_value_one()); | |
342 | prv->dmp1 = BN_new(); | |
343 | BN_mod(prv->dmp1, prv->d, aux, ctx); | |
344 | ||
345 | BN_clear_free(aux); | |
346 | BN_CTX_free(ctx); | |
347 | ||
348 | buffer_free(&decrypted); | |
349 | ||
350 | return 1; | |
8efc0c15 | 351 | } |