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 #ifdef HAVE_OPENSSL_THREAD_STOP /* openssl-1.1 or later */
  64         OPENSSL_thread_stop();
  65 #else /* openssl-1.0 */
  66         ERR_remove_thread_state(NULL);
  67 #endif
  68         EVP_cleanup();
  69 }
  70
  71 /*
  72  * The public key loading functions below were inspired by corresponding code
  73  * of openssh-5.2p1, Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo,
  74  * Finland. However, not much of the original code remains.
  75  */
  76
  77 static int read_bignum(const unsigned char *buf, size_t len, BIGNUM **result)
  78 {
  79         const unsigned char *p = buf, *end = buf + len;
  80         uint32_t bnsize;
  81         BIGNUM *bn;
  82
  83         if (p + 4 < p)
  84                 return -E_BIGNUM;
  85         if (p + 4 > end)
  86                 return -E_BIGNUM;
  87         bnsize = read_u32_be(p);
  88         PARA_DEBUG_LOG("bnsize: %u\n", bnsize);
  89         p += 4;
  90         if (p + bnsize < p)
  91                 return -E_BIGNUM;
  92         if (p + bnsize > end)
  93                 return -E_BIGNUM;
  94         if (bnsize > 8192)
  95                 return -E_BIGNUM;
  96         bn = BN_bin2bn(p, bnsize, NULL);
  97         if (!bn)
  98                 return -E_BIGNUM;
  99         *result = bn;
 100         return bnsize + 4;
 101 }
 102
 103 static int read_rsa_bignums(const unsigned char *blob, int blen, RSA **result)
 104 {
 105         int ret;
 106         RSA *rsa;
 107         BIGNUM *n, *e;
 108         const unsigned char *p = blob, *end = blob + blen;
 109
 110         rsa = RSA_new();
 111         if (!rsa)
 112                 return -E_BIGNUM;
 113         ret = read_bignum(p, end - p, &e);
 114         if (ret < 0)
 115                 goto free_rsa;
 116         p += ret;
 117         ret = read_bignum(p, end - p, &n);
 118         if (ret < 0)
 119                 goto free_e;
 120 #ifdef HAVE_RSA_SET0_KEY
 121         RSA_set0_key(rsa, n, e, NULL);
 122 #else
 123         rsa->n = n;
 124         rsa->e = e;
 125 #endif
 126         *result = rsa;
 127         return 1;
 128 free_e:
 129         BN_free(e);
 130 free_rsa:
 131         RSA_free(rsa);
 132         return ret;
 133 }
 134
 135 static int read_pem_private_key(const char *path, RSA **rsa)
 136 {
 137         EVP_PKEY *pkey;
 138         BIO *bio = BIO_new(BIO_s_file());
 139
 140         *rsa = NULL;
 141         if (!bio)
 142                 return -E_PRIVATE_KEY;
 143         if (BIO_read_filename(bio, path) <= 0)
 144                 goto bio_free;
 145         pkey = PEM_read_bio_PrivateKey(bio, NULL, NULL, NULL);
 146         if (!pkey)
 147                 goto bio_free;
 148         *rsa = EVP_PKEY_get1_RSA(pkey);
 149         EVP_PKEY_free(pkey);
 150 bio_free:
 151         BIO_free(bio);
 152         return *rsa? RSA_size(*rsa) : -E_PRIVATE_KEY;
 153 }
 154
 155 static int read_private_rsa_params(const unsigned char *blob,
 156                 const unsigned char *end, RSA **result)
 157 {
 158         int ret;
 159         RSA *rsa;
 160         BN_CTX *ctx;
 161         BIGNUM *n, *e, *d, *iqmp, *p, *q; /* stored in the key file */
 162         BIGNUM *dmp1, *dmq1; /* these will be computed */
 163         BIGNUM *tmp;
 164         const unsigned char *cp = blob;
 165
 166         rsa = RSA_new();
 167         if (!rsa)
 168                 return -E_BIGNUM;
 169         ret = -E_BIGNUM;
 170         tmp = BN_new();
 171         if (!tmp)
 172                 goto free_rsa;
 173         ctx = BN_CTX_new();
 174         if (!ctx)
 175                 goto free_tmp;
 176         dmp1 = BN_new();
 177         if (!dmp1)
 178                 goto free_ctx;
 179         dmq1 = BN_new();
 180         if (!dmq1)
 181                 goto free_dmp1;
 182         ret = read_bignum(cp, end - cp, &n);
 183         if (ret < 0)
 184                 goto free_dmq1;
 185         cp += ret;
 186         ret = read_bignum(cp, end - cp, &e);
 187         if (ret < 0)
 188                 goto free_n;
 189         cp += ret;
 190         ret = read_bignum(cp, end - cp, &d);
 191         if (ret < 0)
 192                 goto free_e;
 193         cp += ret;
 194         ret = read_bignum(cp, end - cp, &iqmp);
 195         if (ret < 0)
 196                 goto free_d;
 197         cp += ret;
 198         ret = read_bignum(cp, end - cp, &p);
 199         if (ret < 0)
 200                 goto free_iqmp;
 201         cp += ret;
 202         ret = read_bignum(cp, end - cp, &q);
 203         if (ret < 0)
 204                 goto free_p;
 205         ret = -E_BIGNUM;
 206         if (!BN_sub(tmp, q, BN_value_one()))
 207                 goto free_q;
 208         if (!BN_mod(dmp1, d, tmp, ctx))
 209                 goto free_q;
 210         if (!BN_sub(tmp, q, BN_value_one()))
 211                 goto free_q;
 212         if (!BN_mod(dmq1, d, tmp, ctx))
 213                 goto free_q;
 214 #ifdef HAVE_RSA_SET0_KEY
 215         RSA_set0_key(rsa, n, e, d);
 216         RSA_set0_factors(rsa, p, q);
 217         RSA_set0_crt_params(rsa, dmp1, dmq1, iqmp);
 218 #else
 219         rsa->n = n;
 220         rsa->e = e;
 221         rsa->d = d;
 222         rsa->p = p;
 223         rsa->q = q;
 224         rsa->dmp1 = dmp1;
 225         rsa->dmq1 = dmq1;
 226         rsa->iqmp = iqmp;
 227 #endif
 228         *result = rsa;
 229         ret = 1;
 230         goto free_ctx;
 231 free_q:
 232         BN_clear_free(q);
 233 free_p:
 234         BN_clear_free(p);
 235 free_iqmp:
 236         BN_clear_free(iqmp);
 237 free_d:
 238         BN_clear_free(d);
 239 free_e:
 240         BN_free(e);
 241 free_n:
 242         BN_free(n);
 243 free_dmq1:
 244         BN_clear_free(dmq1);
 245 free_dmp1:
 246         BN_clear_free(dmp1);
 247 free_ctx:
 248         BN_CTX_free(ctx);
 249 free_tmp:
 250         BN_clear_free(tmp);
 251 free_rsa:
 252         if (ret < 0)
 253                 RSA_free(rsa);
 254         return ret;
 255 }
 256
 257 static int get_private_key(const char *path, RSA **rsa)
 258 {
 259         int ret;
 260         unsigned char *blob, *end;
 261         size_t blob_size;
 262
 263         *rsa = NULL;
 264         ret = decode_private_key(path, &blob, &blob_size);
 265         if (ret < 0)
 266                 return ret;
 267         end = blob + blob_size;
 268         if (ret == PKT_OPENSSH) {
 269                 ret = find_openssh_bignum_offset(blob, blob_size);
 270                 if (ret < 0)
 271                         goto free_blob;
 272                 PARA_INFO_LOG("reading RSA params at offset %d\n", ret);
 273                 ret = read_private_rsa_params(blob + ret, end, rsa);
 274         } else
 275                 ret = read_pem_private_key(path, rsa);
 276 free_blob:
 277         free(blob);
 278         return ret;
 279 }
 280
 281 int apc_get_pubkey(const char *key_file, struct asymmetric_key **result)
 282 {
 283         unsigned char *blob;
 284         size_t decoded_size;
 285         int ret;
 286         struct asymmetric_key *key = para_malloc(sizeof(*key));
 287
 288         ret = decode_public_key(key_file, &blob, &decoded_size);
 289         if (ret < 0)
 290                 goto out;
 291         ret = read_rsa_bignums(blob + ret, decoded_size - ret, &key->rsa);
 292         if (ret < 0)
 293                 goto free_blob;
 294         ret = RSA_size(key->rsa);
 295         assert(ret > 0);
 296         *result = key;
 297 free_blob:
 298         free(blob);
 299 out:
 300         if (ret < 0) {
 301                 free(key);
 302                 *result = NULL;
 303                 PARA_ERROR_LOG("can not load key %s\n", key_file);
 304         }
 305         return ret;
 306 }
 307
 308 void apc_free_pubkey(struct asymmetric_key *key)
 309 {
 310         if (!key)
 311                 return;
 312         RSA_free(key->rsa);
 313         free(key);
 314 }
 315
 316 int apc_priv_decrypt(const char *key_file, unsigned char *outbuf,
 317                 unsigned char *inbuf, int inlen)
 318 {
 319         struct asymmetric_key *priv;
 320         int ret;
 321
 322         ret = check_private_key_file(key_file);
 323         if (ret < 0)
 324                 return ret;
 325         if (inlen < 0)
 326                 return -E_RSA;
 327         priv = para_malloc(sizeof(*priv));
 328         ret = get_private_key(key_file, &priv->rsa);
 329         if (ret < 0) {
 330                 free(priv);
 331                 return ret;
 332         }
 333         /*
 334          * RSA is vulnerable to timing attacks. Generate a random blinding
 335          * factor to protect against this kind of attack.
 336          */
 337         ret = -E_BLINDING;
 338         if (RSA_blinding_on(priv->rsa, NULL) == 0)
 339                 goto out;
 340         ret = RSA_private_decrypt(inlen, inbuf, outbuf, priv->rsa,
 341                 RSA_PKCS1_OAEP_PADDING);
 342         RSA_blinding_off(priv->rsa);
 343         if (ret <= 0)
 344                 ret = -E_DECRYPT;
 345 out:
 346         RSA_free(priv->rsa);
 347         free(priv);
 348         return ret;
 349 }
 350
 351 int apc_pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
 352                 unsigned len, unsigned char *outbuf)
 353 {
 354         int ret, flen = len; /* RSA_public_encrypt expects a signed int */
 355
 356         if (flen < 0)
 357                 return -E_ENCRYPT;
 358         ret = RSA_public_encrypt(flen, inbuf, outbuf, pub->rsa,
 359                 RSA_PKCS1_OAEP_PADDING);
 360         return ret < 0? -E_ENCRYPT : ret;
 361 }
 362
 363 struct stream_cipher {
 364         EVP_CIPHER_CTX *aes;
 365 };
 366
 367 struct stream_cipher *sc_new(const unsigned char *data, int len)
 368 {
 369         struct stream_cipher *sc = para_malloc(sizeof(*sc));
 370
 371         assert(len >= 2 * AES_CRT128_BLOCK_SIZE);
 372         sc->aes = EVP_CIPHER_CTX_new();
 373         EVP_EncryptInit_ex(sc->aes, EVP_aes_128_ctr(), NULL, data,
 374                 data + AES_CRT128_BLOCK_SIZE);
 375         return sc;
 376 }
 377
 378 void sc_free(struct stream_cipher *sc)
 379 {
 380         if (!sc)
 381                 return;
 382         EVP_CIPHER_CTX_free(sc->aes);
 383         free(sc);
 384 }
 385
 386 static void aes_ctr128_crypt(EVP_CIPHER_CTX *ctx, struct iovec *src,
 387                 struct iovec *dst)
 388 {
 389         int ret, inlen = src->iov_len, outlen, tmplen;
 390
 391         *dst = (typeof(*dst)) {
 392                 /* Add one for the terminating zero byte. */
 393                 .iov_base = para_malloc(inlen + 1),
 394                 .iov_len = inlen
 395         };
 396         ret = EVP_EncryptUpdate(ctx, dst->iov_base, &outlen, src->iov_base, inlen);
 397         assert(ret != 0);
 398         ret = EVP_EncryptFinal_ex(ctx, dst->iov_base + outlen, &tmplen);
 399         assert(ret != 0);
 400         outlen += tmplen;
 401         ((char *)dst->iov_base)[outlen] = '\0';
 402         dst->iov_len = outlen;
 403 }
 404
 405 void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst)
 406 {
 407         return aes_ctr128_crypt(sc->aes, src, dst);
 408 }
 409
 410 void hash_function(const char *data, unsigned long len, unsigned char *hash)
 411 {
 412         SHA_CTX c;
 413         SHA1_Init(&c);
 414         SHA1_Update(&c, data, len);
 415         SHA1_Final(hash, &c);
 416 }