openssl: RSA fixes for openssl-1.1.
[paraslash.git] / crypt.c
1 /*
2 * Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file crypt.c Openssl-based encryption/decryption routines. */
8
9 #include <regex.h>
10 #include <sys/types.h>
11 #include <sys/socket.h>
12 #include <openssl/rand.h>
13 #include <openssl/err.h>
14 #include <openssl/rc4.h>
15 #include <openssl/pem.h>
16 #include <openssl/sha.h>
17 #include <openssl/bn.h>
18 #include <openssl/aes.h>
19
20 #include "para.h"
21 #include "error.h"
22 #include "string.h"
23 #include "crypt.h"
24 #include "fd.h"
25 #include "crypt_backend.h"
26
27 struct asymmetric_key {
28 RSA *rsa;
29 };
30
31 void get_random_bytes_or_die(unsigned char *buf, int num)
32 {
33 unsigned long err;
34
35 /* RAND_bytes() returns 1 on success, 0 otherwise. */
36 if (RAND_bytes(buf, num) == 1)
37 return;
38 err = ERR_get_error();
39 PARA_EMERG_LOG("%s\n", ERR_reason_error_string(err));
40 exit(EXIT_FAILURE);
41 }
42
43 /*
44 * Read 64 bytes from /dev/urandom and adds them to the SSL PRNG. Seed the PRNG
45 * used by random() with a random seed obtained from SSL. If /dev/random is not
46 * readable the function calls exit().
47 *
48 * \sa RAND_load_file(3), \ref get_random_bytes_or_die(), srandom(3),
49 * random(3), \ref para_random().
50 */
51 void init_random_seed_or_die(void)
52 {
53 int seed, ret = RAND_load_file("/dev/urandom", 64);
54
55 if (ret != 64) {
56 PARA_EMERG_LOG("could not seed PRNG (ret = %d)\n", ret);
57 exit(EXIT_FAILURE);
58 }
59 get_random_bytes_or_die((unsigned char *)&seed, sizeof(seed));
60 srandom(seed);
61 }
62
63 static EVP_PKEY *load_key(const char *file, int private)
64 {
65 BIO *key;
66 EVP_PKEY *pkey = NULL;
67 int ret = check_key_file(file, private);
68
69 if (ret < 0) {
70 PARA_ERROR_LOG("%s\n", para_strerror(-ret));
71 return NULL;
72 }
73 key = BIO_new(BIO_s_file());
74 if (!key)
75 return NULL;
76 if (BIO_read_filename(key, file) > 0) {
77 if (private == LOAD_PRIVATE_KEY)
78 pkey = PEM_read_bio_PrivateKey(key, NULL, NULL, NULL);
79 else
80 pkey = PEM_read_bio_PUBKEY(key, NULL, NULL, NULL);
81 }
82 BIO_free(key);
83 return pkey;
84 }
85
86 static int get_openssl_key(const char *key_file, RSA **rsa, int private)
87 {
88 EVP_PKEY *key = load_key(key_file, private);
89
90 if (!key)
91 return (private == LOAD_PRIVATE_KEY)? -E_PRIVATE_KEY
92 : -E_PUBLIC_KEY;
93 *rsa = EVP_PKEY_get1_RSA(key);
94 EVP_PKEY_free(key);
95 if (!*rsa)
96 return -E_RSA;
97 return RSA_size(*rsa);
98 }
99
100 /*
101 * The public key loading functions below were inspired by corresponding code
102 * of openssh-5.2p1, Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo,
103 * Finland. However, not much of the original code remains.
104 */
105
106 static int read_bignum(const unsigned char *buf, size_t len, BIGNUM **result)
107 {
108 const unsigned char *p = buf, *end = buf + len;
109 uint32_t bnsize;
110 BIGNUM *bn;
111
112 if (p + 4 < p)
113 return -E_BIGNUM;
114 if (p + 4 > end)
115 return -E_BIGNUM;
116 bnsize = read_ssh_u32(p);
117 PARA_DEBUG_LOG("bnsize: %u\n", bnsize);
118 p += 4;
119 if (p + bnsize < p)
120 return -E_BIGNUM;
121 if (p + bnsize > end)
122 return -E_BIGNUM;
123 if (bnsize > 8192)
124 return -E_BIGNUM;
125 bn = BN_bin2bn(p, bnsize, NULL);
126 if (!bn)
127 return -E_BIGNUM;
128 *result = bn;
129 return bnsize + 4;
130 }
131
132 static int read_rsa_bignums(const unsigned char *blob, int blen, RSA **result)
133 {
134 int ret;
135 RSA *rsa;
136 BIGNUM *n, *e;
137 const unsigned char *p = blob, *end = blob + blen;
138
139 rsa = RSA_new();
140 if (!rsa)
141 return -E_BIGNUM;
142 ret = read_bignum(p, end - p, &e);
143 if (ret < 0)
144 goto fail;
145 p += ret;
146 ret = read_bignum(p, end - p, &n);
147 if (ret < 0)
148 goto fail;
149 #ifdef HAVE_RSA_SET0_KEY
150 RSA_set0_key(rsa, n, e, NULL);
151 #else
152 rsa->n = n;
153 rsa->e = e;
154 #endif
155 *result = rsa;
156 return 1;
157 fail:
158 RSA_free(rsa);
159 return ret;
160 }
161
162 int get_asymmetric_key(const char *key_file, int private,
163 struct asymmetric_key **result)
164 {
165 struct asymmetric_key *key = NULL;
166 void *map = NULL;
167 unsigned char *blob = NULL;
168 size_t map_size, blob_size, decoded_size;
169 int ret, ret2;
170 char *cp;
171
172 key = para_malloc(sizeof(*key));
173 if (private) {
174 ret = get_openssl_key(key_file, &key->rsa, LOAD_PRIVATE_KEY);
175 goto out;
176 }
177 ret = mmap_full_file(key_file, O_RDONLY, &map, &map_size, NULL);
178 if (ret < 0)
179 goto out;
180 ret = is_ssh_rsa_key(map, map_size);
181 if (!ret) {
182 ret = para_munmap(map, map_size);
183 map = NULL;
184 if (ret < 0)
185 goto out;
186 ret = get_openssl_key(key_file, &key->rsa, LOAD_PUBLIC_KEY);
187 goto out;
188 }
189 cp = map + ret;
190 PARA_INFO_LOG("decoding public rsa-ssh key %s\n", key_file);
191 ret = -ERRNO_TO_PARA_ERROR(EOVERFLOW);
192 if (map_size > INT_MAX / 4)
193 goto out_unmap;
194 blob_size = 2 * map_size;
195 blob = para_malloc(blob_size);
196 ret = uudecode(cp, blob, blob_size);
197 if (ret < 0)
198 goto out_unmap;
199 decoded_size = ret;
200 ret = check_ssh_key_header(blob, decoded_size);
201 if (ret < 0)
202 goto out_unmap;
203 ret = read_rsa_bignums(blob + ret, decoded_size - ret, &key->rsa);
204 if (ret < 0)
205 goto out_unmap;
206 ret = RSA_size(key->rsa);
207 out_unmap:
208 ret2 = para_munmap(map, map_size);
209 if (ret >= 0 && ret2 < 0)
210 ret = ret2;
211 out:
212 if (ret < 0) {
213 free(key);
214 *result = NULL;
215 PARA_ERROR_LOG("key %s: %s\n", key_file, para_strerror(-ret));
216 } else
217 *result = key;
218 free(blob);
219 return ret;
220 }
221
222 void free_asymmetric_key(struct asymmetric_key *key)
223 {
224 if (!key)
225 return;
226 RSA_free(key->rsa);
227 free(key);
228 }
229
230 int priv_decrypt(const char *key_file, unsigned char *outbuf,
231 unsigned char *inbuf, int inlen)
232 {
233 struct asymmetric_key *priv;
234 int ret;
235
236 if (inlen < 0)
237 return -E_RSA;
238 ret = get_asymmetric_key(key_file, LOAD_PRIVATE_KEY, &priv);
239 if (ret < 0)
240 return ret;
241 /*
242 * RSA is vulnerable to timing attacks. Generate a random blinding
243 * factor to protect against this kind of attack.
244 */
245 ret = -E_BLINDING;
246 if (RSA_blinding_on(priv->rsa, NULL) == 0)
247 goto out;
248 ret = RSA_private_decrypt(inlen, inbuf, outbuf, priv->rsa,
249 RSA_PKCS1_OAEP_PADDING);
250 RSA_blinding_off(priv->rsa);
251 if (ret <= 0)
252 ret = -E_DECRYPT;
253 out:
254 free_asymmetric_key(priv);
255 return ret;
256 }
257
258 int pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
259 unsigned len, unsigned char *outbuf)
260 {
261 int ret, flen = len; /* RSA_public_encrypt expects a signed int */
262
263 if (flen < 0)
264 return -E_ENCRYPT;
265 ret = RSA_public_encrypt(flen, inbuf, outbuf, pub->rsa,
266 RSA_PKCS1_OAEP_PADDING);
267 return ret < 0? -E_ENCRYPT : ret;
268 }
269
270 struct stream_cipher {
271 bool use_aes;
272 union {
273 RC4_KEY rc4_key;
274 EVP_CIPHER_CTX *aes;
275 } context;
276 };
277
278 struct stream_cipher *sc_new(const unsigned char *data, int len,
279 bool use_aes)
280 {
281 struct stream_cipher *sc = para_malloc(sizeof(*sc));
282
283 sc->use_aes = use_aes;
284 if (!use_aes) {
285 RC4_set_key(&sc->context.rc4_key, len, data);
286 return sc;
287 }
288 assert(len >= 2 * AES_CRT128_BLOCK_SIZE);
289 sc->context.aes = EVP_CIPHER_CTX_new();
290 EVP_EncryptInit_ex(sc->context.aes, EVP_aes_128_ctr(), NULL, data,
291 data + AES_CRT128_BLOCK_SIZE);
292 return sc;
293 }
294
295 void sc_free(struct stream_cipher *sc)
296 {
297 if (!sc)
298 return;
299 EVP_CIPHER_CTX_free(sc->context.aes);
300 free(sc);
301 }
302
303 /**
304 * The RC4() implementation of openssl apparently reads and writes data in
305 * blocks of 8 bytes. So we have to make sure our buffer sizes are a multiple
306 * of this.
307 */
308 #define RC4_ALIGN 8
309
310 static void rc4_crypt(RC4_KEY *key, struct iovec *src, struct iovec *dst)
311 {
312 size_t len = src->iov_len, l1, l2;
313
314 assert(len > 0);
315 assert(len < ((typeof(src->iov_len))-1) / 2);
316 l1 = ROUND_DOWN(len, RC4_ALIGN);
317 l2 = ROUND_UP(len, RC4_ALIGN);
318
319 *dst = (typeof(*dst)) {
320 /* Add one for the terminating zero byte. */
321 .iov_base = para_malloc(l2 + 1),
322 .iov_len = len
323 };
324 RC4(key, l1, src->iov_base, dst->iov_base);
325 if (len > l1) {
326 unsigned char remainder[RC4_ALIGN] = "";
327 memcpy(remainder, src->iov_base + l1, len - l1);
328 RC4(key, len - l1, remainder, dst->iov_base + l1);
329 }
330 ((char *)dst->iov_base)[len] = '\0';
331 }
332
333 static void aes_ctr128_crypt(EVP_CIPHER_CTX *ctx, struct iovec *src,
334 struct iovec *dst)
335 {
336 int ret, inlen = src->iov_len, outlen, tmplen;
337
338 *dst = (typeof(*dst)) {
339 /* Add one for the terminating zero byte. */
340 .iov_base = para_malloc(inlen + 1),
341 .iov_len = inlen
342 };
343 ret = EVP_EncryptUpdate(ctx, dst->iov_base, &outlen, src->iov_base, inlen);
344 assert(ret != 0);
345 ret = EVP_EncryptFinal_ex(ctx, dst->iov_base + outlen, &tmplen);
346 assert(ret != 0);
347 outlen += tmplen;
348 ((char *)dst->iov_base)[outlen] = '\0';
349 dst->iov_len = outlen;
350 }
351
352 void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst)
353 {
354 if (sc->use_aes)
355 return aes_ctr128_crypt(sc->context.aes, src, dst);
356 return rc4_crypt(&sc->context.rc4_key, src, dst);
357 }
358
359 void hash_function(const char *data, unsigned long len, unsigned char *hash)
360 {
361 SHA_CTX c;
362 SHA1_Init(&c);
363 SHA1_Update(&c, data, len);
364 SHA1_Final(hash, &c);
365 }