vss: Improve error diagnostics.
[paraslash.git] / openssl.c
1 /* Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
2
3 /** \file openssl.c Openssl-based encryption/decryption routines. */
4
5 #include <regex.h>
6 #include <sys/types.h>
7 #include <sys/socket.h>
8 #include <openssl/rand.h>
9 #include <openssl/err.h>
10 #include <openssl/pem.h>
11 #include <openssl/sha.h>
12 #include <openssl/bn.h>
13 #include <openssl/aes.h>
14
15 #include "para.h"
16 #include "error.h"
17 #include "string.h"
18 #include "crypt.h"
19 #include "crypt_backend.h"
20 #include "portable_io.h"
21
22 struct asymmetric_key {
23 RSA *rsa;
24 };
25
26 void get_random_bytes_or_die(unsigned char *buf, int num)
27 {
28 unsigned long err;
29
30 /* RAND_bytes() returns 1 on success, 0 otherwise. */
31 if (RAND_bytes(buf, num) == 1)
32 return;
33 err = ERR_get_error();
34 PARA_EMERG_LOG("%s\n", ERR_reason_error_string(err));
35 exit(EXIT_FAILURE);
36 }
37
38 /*
39 * Read 64 bytes from /dev/urandom and add them to the SSL PRNG. Seed the PRNG
40 * used by random(3) with a random seed obtained from SSL. If /dev/urandom is
41 * not readable, the function calls exit().
42 *
43 * \sa RAND_load_file(3), \ref get_random_bytes_or_die(), srandom(3),
44 * random(3), \ref para_random().
45 */
46 void crypt_init(void)
47 {
48 int seed, ret = RAND_load_file("/dev/urandom", 64);
49
50 if (ret != 64) {
51 PARA_EMERG_LOG("could not seed PRNG (ret = %d)\n", ret);
52 exit(EXIT_FAILURE);
53 }
54 get_random_bytes_or_die((unsigned char *)&seed, sizeof(seed));
55 srandom(seed);
56 }
57
58 void crypt_shutdown(void)
59 {
60 #ifdef HAVE_CRYPTO_CLEANUP_ALL_EX_DATA
61 CRYPTO_cleanup_all_ex_data();
62 #endif
63 }
64
65 /*
66 * The public key loading functions below were inspired by corresponding code
67 * of openssh-5.2p1, Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo,
68 * Finland. However, not much of the original code remains.
69 */
70
71 static int read_bignum(const unsigned char *buf, size_t len, BIGNUM **result)
72 {
73 const unsigned char *p = buf, *end = buf + len;
74 uint32_t bnsize;
75 BIGNUM *bn;
76
77 if (p + 4 < p)
78 return -E_BIGNUM;
79 if (p + 4 > end)
80 return -E_BIGNUM;
81 bnsize = read_u32_be(p);
82 PARA_DEBUG_LOG("bnsize: %u\n", bnsize);
83 p += 4;
84 if (p + bnsize < p)
85 return -E_BIGNUM;
86 if (p + bnsize > end)
87 return -E_BIGNUM;
88 if (bnsize > 8192)
89 return -E_BIGNUM;
90 bn = BN_bin2bn(p, bnsize, NULL);
91 if (!bn)
92 return -E_BIGNUM;
93 *result = bn;
94 return bnsize + 4;
95 }
96
97 static int read_rsa_bignums(const unsigned char *blob, int blen, RSA **result)
98 {
99 int ret;
100 RSA *rsa;
101 BIGNUM *n, *e;
102 const unsigned char *p = blob, *end = blob + blen;
103
104 rsa = RSA_new();
105 if (!rsa)
106 return -E_BIGNUM;
107 ret = read_bignum(p, end - p, &e);
108 if (ret < 0)
109 goto free_rsa;
110 p += ret;
111 ret = read_bignum(p, end - p, &n);
112 if (ret < 0)
113 goto free_e;
114 #ifdef HAVE_RSA_SET0_KEY
115 RSA_set0_key(rsa, n, e, NULL);
116 #else
117 rsa->n = n;
118 rsa->e = e;
119 #endif
120 *result = rsa;
121 return 1;
122 free_e:
123 BN_free(e);
124 free_rsa:
125 RSA_free(rsa);
126 return ret;
127 }
128
129 static int read_pem_private_key(const char *path, RSA **rsa)
130 {
131 EVP_PKEY *pkey;
132 BIO *bio = BIO_new(BIO_s_file());
133
134 *rsa = NULL;
135 if (!bio)
136 return -E_PRIVATE_KEY;
137 if (BIO_read_filename(bio, path) <= 0)
138 goto bio_free;
139 pkey = PEM_read_bio_PrivateKey(bio, NULL, NULL, NULL);
140 if (!pkey)
141 goto bio_free;
142 *rsa = EVP_PKEY_get1_RSA(pkey);
143 EVP_PKEY_free(pkey);
144 bio_free:
145 BIO_free(bio);
146 return *rsa? RSA_size(*rsa) : -E_PRIVATE_KEY;
147 }
148
149 static int read_private_rsa_params(const unsigned char *blob,
150 const unsigned char *end, RSA **result)
151 {
152 int ret;
153 RSA *rsa;
154 BN_CTX *ctx;
155 BIGNUM *n, *e, *d, *iqmp, *p, *q; /* stored in the key file */
156 BIGNUM *dmp1, *dmq1; /* these will be computed */
157 BIGNUM *tmp;
158 const unsigned char *cp = blob;
159
160 rsa = RSA_new();
161 if (!rsa)
162 return -E_BIGNUM;
163 ret = -E_BIGNUM;
164 tmp = BN_new();
165 if (!tmp)
166 goto free_rsa;
167 ctx = BN_CTX_new();
168 if (!ctx)
169 goto free_tmp;
170 dmp1 = BN_new();
171 if (!dmp1)
172 goto free_ctx;
173 dmq1 = BN_new();
174 if (!dmq1)
175 goto free_dmp1;
176 ret = read_bignum(cp, end - cp, &n);
177 if (ret < 0)
178 goto free_dmq1;
179 cp += ret;
180 ret = read_bignum(cp, end - cp, &e);
181 if (ret < 0)
182 goto free_n;
183 cp += ret;
184 ret = read_bignum(cp, end - cp, &d);
185 if (ret < 0)
186 goto free_e;
187 cp += ret;
188 ret = read_bignum(cp, end - cp, &iqmp);
189 if (ret < 0)
190 goto free_d;
191 cp += ret;
192 ret = read_bignum(cp, end - cp, &p);
193 if (ret < 0)
194 goto free_iqmp;
195 cp += ret;
196 ret = read_bignum(cp, end - cp, &q);
197 if (ret < 0)
198 goto free_p;
199 ret = -E_BIGNUM;
200 if (!BN_sub(tmp, q, BN_value_one()))
201 goto free_q;
202 if (!BN_mod(dmp1, d, tmp, ctx))
203 goto free_q;
204 if (!BN_sub(tmp, q, BN_value_one()))
205 goto free_q;
206 if (!BN_mod(dmq1, d, tmp, ctx))
207 goto free_q;
208 #ifdef HAVE_RSA_SET0_KEY
209 RSA_set0_key(rsa, n, e, d);
210 RSA_set0_factors(rsa, p, q);
211 RSA_set0_crt_params(rsa, dmp1, dmq1, iqmp);
212 #else
213 rsa->n = n;
214 rsa->e = e;
215 rsa->d = d;
216 rsa->p = p;
217 rsa->q = q;
218 rsa->dmp1 = dmp1;
219 rsa->dmq1 = dmq1;
220 rsa->iqmp = iqmp;
221 #endif
222 *result = rsa;
223 ret = 1;
224 goto free_ctx;
225 free_q:
226 BN_clear_free(q);
227 free_p:
228 BN_clear_free(p);
229 free_iqmp:
230 BN_clear_free(iqmp);
231 free_d:
232 BN_clear_free(d);
233 free_e:
234 BN_free(e);
235 free_n:
236 BN_free(n);
237 free_dmq1:
238 BN_clear_free(dmq1);
239 free_dmp1:
240 BN_clear_free(dmp1);
241 free_ctx:
242 BN_CTX_free(ctx);
243 free_tmp:
244 BN_clear_free(tmp);
245 free_rsa:
246 if (ret < 0)
247 RSA_free(rsa);
248 return ret;
249 }
250
251 static int get_private_key(const char *path, RSA **rsa)
252 {
253 int ret;
254 unsigned char *blob, *end;
255 size_t blob_size;
256
257 *rsa = NULL;
258 ret = decode_private_key(path, &blob, &blob_size);
259 if (ret < 0)
260 return ret;
261 end = blob + blob_size;
262 if (ret == PKT_OPENSSH) {
263 ret = find_openssh_bignum_offset(blob, blob_size);
264 if (ret < 0)
265 goto free_blob;
266 PARA_INFO_LOG("reading RSA params at offset %d\n", ret);
267 ret = read_private_rsa_params(blob + ret, end, rsa);
268 } else
269 ret = read_pem_private_key(path, rsa);
270 free_blob:
271 free(blob);
272 return ret;
273 }
274
275 int apc_get_pubkey(const char *key_file, struct asymmetric_key **result)
276 {
277 unsigned char *blob;
278 size_t decoded_size;
279 int ret;
280 struct asymmetric_key *key = para_malloc(sizeof(*key));
281
282 ret = decode_public_key(key_file, &blob, &decoded_size);
283 if (ret < 0)
284 goto out;
285 ret = read_rsa_bignums(blob + ret, decoded_size - ret, &key->rsa);
286 if (ret < 0)
287 goto free_blob;
288 ret = RSA_size(key->rsa);
289 assert(ret > 0);
290 *result = key;
291 free_blob:
292 free(blob);
293 out:
294 if (ret < 0) {
295 free(key);
296 *result = NULL;
297 PARA_ERROR_LOG("can not load key %s\n", key_file);
298 }
299 return ret;
300 }
301
302 void apc_free_pubkey(struct asymmetric_key *key)
303 {
304 if (!key)
305 return;
306 RSA_free(key->rsa);
307 free(key);
308 }
309
310 int apc_priv_decrypt(const char *key_file, unsigned char *outbuf,
311 unsigned char *inbuf, int inlen)
312 {
313 struct asymmetric_key *priv;
314 int ret;
315
316 ret = check_private_key_file(key_file);
317 if (ret < 0)
318 return ret;
319 if (inlen < 0)
320 return -E_RSA;
321 priv = para_malloc(sizeof(*priv));
322 ret = get_private_key(key_file, &priv->rsa);
323 if (ret < 0) {
324 free(priv);
325 return ret;
326 }
327 /*
328 * RSA is vulnerable to timing attacks. Generate a random blinding
329 * factor to protect against this kind of attack.
330 */
331 ret = -E_BLINDING;
332 if (RSA_blinding_on(priv->rsa, NULL) == 0)
333 goto out;
334 ret = RSA_private_decrypt(inlen, inbuf, outbuf, priv->rsa,
335 RSA_PKCS1_OAEP_PADDING);
336 RSA_blinding_off(priv->rsa);
337 if (ret <= 0)
338 ret = -E_DECRYPT;
339 out:
340 RSA_free(priv->rsa);
341 free(priv);
342 return ret;
343 }
344
345 int apc_pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
346 unsigned len, unsigned char *outbuf)
347 {
348 int ret, flen = len; /* RSA_public_encrypt expects a signed int */
349
350 if (flen < 0)
351 return -E_ENCRYPT;
352 ret = RSA_public_encrypt(flen, inbuf, outbuf, pub->rsa,
353 RSA_PKCS1_OAEP_PADDING);
354 return ret < 0? -E_ENCRYPT : ret;
355 }
356
357 struct stream_cipher {
358 EVP_CIPHER_CTX *aes;
359 };
360
361 struct stream_cipher *sc_new(const unsigned char *data, int len)
362 {
363 struct stream_cipher *sc = para_malloc(sizeof(*sc));
364
365 assert(len >= 2 * AES_CRT128_BLOCK_SIZE);
366 sc->aes = EVP_CIPHER_CTX_new();
367 EVP_EncryptInit_ex(sc->aes, EVP_aes_128_ctr(), NULL, data,
368 data + AES_CRT128_BLOCK_SIZE);
369 return sc;
370 }
371
372 void sc_free(struct stream_cipher *sc)
373 {
374 if (!sc)
375 return;
376 EVP_CIPHER_CTX_free(sc->aes);
377 free(sc);
378 }
379
380 static void aes_ctr128_crypt(EVP_CIPHER_CTX *ctx, struct iovec *src,
381 struct iovec *dst)
382 {
383 int ret, inlen = src->iov_len, outlen, tmplen;
384
385 *dst = (typeof(*dst)) {
386 /* Add one for the terminating zero byte. */
387 .iov_base = para_malloc(inlen + 1),
388 .iov_len = inlen
389 };
390 ret = EVP_EncryptUpdate(ctx, dst->iov_base, &outlen, src->iov_base, inlen);
391 assert(ret != 0);
392 ret = EVP_EncryptFinal_ex(ctx, dst->iov_base + outlen, &tmplen);
393 assert(ret != 0);
394 outlen += tmplen;
395 ((char *)dst->iov_base)[outlen] = '\0';
396 dst->iov_len = outlen;
397 }
398
399 void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst)
400 {
401 return aes_ctr128_crypt(sc->aes, src, dst);
402 }
403
404 void hash_function(const char *data, unsigned long len, unsigned char *hash)
405 {
406 SHA_CTX c;
407 SHA1_Init(&c);
408 SHA1_Update(&c, data, len);
409 SHA1_Final(hash, &c);
410 }