build: Check also for CRYPTO_cleanup_all_ex_data.
[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 static int get_private_key(const char *path, RSA **rsa)
66 {
67 EVP_PKEY *pkey;
68 BIO *bio = BIO_new(BIO_s_file());
69
70 *rsa = NULL;
71 if (!bio)
72 return -E_PRIVATE_KEY;
73 if (BIO_read_filename(bio, path) <= 0)
74 goto bio_free;
75 pkey = PEM_read_bio_PrivateKey(bio, NULL, NULL, NULL);
76 if (!pkey)
77 goto bio_free;
78 *rsa = EVP_PKEY_get1_RSA(pkey);
79 EVP_PKEY_free(pkey);
80 bio_free:
81 BIO_free(bio);
82 return *rsa? RSA_size(*rsa) : -E_PRIVATE_KEY;
83 }
84
85 /*
86 * The public key loading functions below were inspired by corresponding code
87 * of openssh-5.2p1, Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo,
88 * Finland. However, not much of the original code remains.
89 */
90
91 static int read_bignum(const unsigned char *buf, size_t len, BIGNUM **result)
92 {
93 const unsigned char *p = buf, *end = buf + len;
94 uint32_t bnsize;
95 BIGNUM *bn;
96
97 if (p + 4 < p)
98 return -E_BIGNUM;
99 if (p + 4 > end)
100 return -E_BIGNUM;
101 bnsize = read_u32_be(p);
102 PARA_DEBUG_LOG("bnsize: %u\n", bnsize);
103 p += 4;
104 if (p + bnsize < p)
105 return -E_BIGNUM;
106 if (p + bnsize > end)
107 return -E_BIGNUM;
108 if (bnsize > 8192)
109 return -E_BIGNUM;
110 bn = BN_bin2bn(p, bnsize, NULL);
111 if (!bn)
112 return -E_BIGNUM;
113 *result = bn;
114 return bnsize + 4;
115 }
116
117 static int read_rsa_bignums(const unsigned char *blob, int blen, RSA **result)
118 {
119 int ret;
120 RSA *rsa;
121 BIGNUM *n, *e;
122 const unsigned char *p = blob, *end = blob + blen;
123
124 rsa = RSA_new();
125 if (!rsa)
126 return -E_BIGNUM;
127 ret = read_bignum(p, end - p, &e);
128 if (ret < 0)
129 goto free_rsa;
130 p += ret;
131 ret = read_bignum(p, end - p, &n);
132 if (ret < 0)
133 goto free_e;
134 #ifdef HAVE_RSA_SET0_KEY
135 RSA_set0_key(rsa, n, e, NULL);
136 #else
137 rsa->n = n;
138 rsa->e = e;
139 #endif
140 *result = rsa;
141 return 1;
142 free_e:
143 BN_free(e);
144 free_rsa:
145 RSA_free(rsa);
146 return ret;
147 }
148
149 int apc_get_pubkey(const char *key_file, struct asymmetric_key **result)
150 {
151 unsigned char *blob;
152 size_t decoded_size;
153 int ret;
154 struct asymmetric_key *key = para_malloc(sizeof(*key));
155
156 ret = decode_ssh_key(key_file, &blob, &decoded_size);
157 if (ret < 0)
158 goto out;
159 ret = read_rsa_bignums(blob + ret, decoded_size - ret, &key->rsa);
160 if (ret < 0)
161 goto free_blob;
162 ret = RSA_size(key->rsa);
163 assert(ret > 0);
164 *result = key;
165 free_blob:
166 free(blob);
167 out:
168 if (ret < 0) {
169 free(key);
170 *result = NULL;
171 PARA_ERROR_LOG("can not load key %s\n", key_file);
172 }
173 return ret;
174 }
175
176 void apc_free_pubkey(struct asymmetric_key *key)
177 {
178 if (!key)
179 return;
180 RSA_free(key->rsa);
181 free(key);
182 }
183
184 int apc_priv_decrypt(const char *key_file, unsigned char *outbuf,
185 unsigned char *inbuf, int inlen)
186 {
187 struct asymmetric_key *priv;
188 int ret;
189
190 ret = check_private_key_file(key_file);
191 if (ret < 0)
192 return ret;
193 if (inlen < 0)
194 return -E_RSA;
195 priv = para_malloc(sizeof(*priv));
196 ret = get_private_key(key_file, &priv->rsa);
197 if (ret < 0) {
198 free(priv);
199 return ret;
200 }
201 /*
202 * RSA is vulnerable to timing attacks. Generate a random blinding
203 * factor to protect against this kind of attack.
204 */
205 ret = -E_BLINDING;
206 if (RSA_blinding_on(priv->rsa, NULL) == 0)
207 goto out;
208 ret = RSA_private_decrypt(inlen, inbuf, outbuf, priv->rsa,
209 RSA_PKCS1_OAEP_PADDING);
210 RSA_blinding_off(priv->rsa);
211 if (ret <= 0)
212 ret = -E_DECRYPT;
213 out:
214 RSA_free(priv->rsa);
215 free(priv);
216 return ret;
217 }
218
219 int apc_pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
220 unsigned len, unsigned char *outbuf)
221 {
222 int ret, flen = len; /* RSA_public_encrypt expects a signed int */
223
224 if (flen < 0)
225 return -E_ENCRYPT;
226 ret = RSA_public_encrypt(flen, inbuf, outbuf, pub->rsa,
227 RSA_PKCS1_OAEP_PADDING);
228 return ret < 0? -E_ENCRYPT : ret;
229 }
230
231 struct stream_cipher {
232 EVP_CIPHER_CTX *aes;
233 };
234
235 struct stream_cipher *sc_new(const unsigned char *data, int len)
236 {
237 struct stream_cipher *sc = para_malloc(sizeof(*sc));
238
239 assert(len >= 2 * AES_CRT128_BLOCK_SIZE);
240 sc->aes = EVP_CIPHER_CTX_new();
241 EVP_EncryptInit_ex(sc->aes, EVP_aes_128_ctr(), NULL, data,
242 data + AES_CRT128_BLOCK_SIZE);
243 return sc;
244 }
245
246 void sc_free(struct stream_cipher *sc)
247 {
248 if (!sc)
249 return;
250 EVP_CIPHER_CTX_free(sc->aes);
251 free(sc);
252 }
253
254 static void aes_ctr128_crypt(EVP_CIPHER_CTX *ctx, struct iovec *src,
255 struct iovec *dst)
256 {
257 int ret, inlen = src->iov_len, outlen, tmplen;
258
259 *dst = (typeof(*dst)) {
260 /* Add one for the terminating zero byte. */
261 .iov_base = para_malloc(inlen + 1),
262 .iov_len = inlen
263 };
264 ret = EVP_EncryptUpdate(ctx, dst->iov_base, &outlen, src->iov_base, inlen);
265 assert(ret != 0);
266 ret = EVP_EncryptFinal_ex(ctx, dst->iov_base + outlen, &tmplen);
267 assert(ret != 0);
268 outlen += tmplen;
269 ((char *)dst->iov_base)[outlen] = '\0';
270 dst->iov_len = outlen;
271 }
272
273 void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst)
274 {
275 return aes_ctr128_crypt(sc->aes, src, dst);
276 }
277
278 void hash_function(const char *data, unsigned long len, unsigned char *hash)
279 {
280 SHA_CTX c;
281 SHA1_Init(&c);
282 SHA1_Update(&c, data, len);
283 SHA1_Final(hash, &c);
284 }