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         CRYPTO_cleanup_all_ex_data();
  61 }
  62
  63 static int get_private_key(const char *path, RSA **rsa)
  64 {
  65         EVP_PKEY *pkey;
  66         BIO *bio = BIO_new(BIO_s_file());
  67
  68         *rsa = NULL;
  69         if (!bio)
  70                 return -E_PRIVATE_KEY;
  71         if (BIO_read_filename(bio, path) <= 0)
  72                 goto bio_free;
  73         pkey = PEM_read_bio_PrivateKey(bio, NULL, NULL, NULL);
  74         if (!pkey)
  75                 goto bio_free;
  76         *rsa = EVP_PKEY_get1_RSA(pkey);
  77         EVP_PKEY_free(pkey);
  78 bio_free:
  79         BIO_free(bio);
  80         return *rsa? RSA_size(*rsa) : -E_PRIVATE_KEY;
  81 }
  82
  83 /*
  84  * The public key loading functions below were inspired by corresponding code
  85  * of openssh-5.2p1, Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo,
  86  * Finland. However, not much of the original code remains.
  87  */
  88
  89 static int read_bignum(const unsigned char *buf, size_t len, BIGNUM **result)
  90 {
  91         const unsigned char *p = buf, *end = buf + len;
  92         uint32_t bnsize;
  93         BIGNUM *bn;
  94
  95         if (p + 4 < p)
  96                 return -E_BIGNUM;
  97         if (p + 4 > end)
  98                 return -E_BIGNUM;
  99         bnsize = read_u32_be(p);
 100         PARA_DEBUG_LOG("bnsize: %u\n", bnsize);
 101         p += 4;
 102         if (p + bnsize < p)
 103                 return -E_BIGNUM;
 104         if (p + bnsize > end)
 105                 return -E_BIGNUM;
 106         if (bnsize > 8192)
 107                 return -E_BIGNUM;
 108         bn = BN_bin2bn(p, bnsize, NULL);
 109         if (!bn)
 110                 return -E_BIGNUM;
 111         *result = bn;
 112         return bnsize + 4;
 113 }
 114
 115 static int read_rsa_bignums(const unsigned char *blob, int blen, RSA **result)
 116 {
 117         int ret;
 118         RSA *rsa;
 119         BIGNUM *n, *e;
 120         const unsigned char *p = blob, *end = blob + blen;
 121
 122         rsa = RSA_new();
 123         if (!rsa)
 124                 return -E_BIGNUM;
 125         ret = read_bignum(p, end - p, &e);
 126         if (ret < 0)
 127                 goto free_rsa;
 128         p += ret;
 129         ret = read_bignum(p, end - p, &n);
 130         if (ret < 0)
 131                 goto free_e;
 132 #ifdef HAVE_RSA_SET0_KEY
 133         RSA_set0_key(rsa, n, e, NULL);
 134 #else
 135         rsa->n = n;
 136         rsa->e = e;
 137 #endif
 138         *result = rsa;
 139         return 1;
 140 free_e:
 141         BN_free(e);
 142 free_rsa:
 143         RSA_free(rsa);
 144         return ret;
 145 }
 146
 147 int apc_get_pubkey(const char *key_file, struct asymmetric_key **result)
 148 {
 149         unsigned char *blob;
 150         size_t decoded_size;
 151         int ret;
 152         struct asymmetric_key *key = para_malloc(sizeof(*key));
 153
 154         ret = decode_ssh_key(key_file, &blob, &decoded_size);
 155         if (ret < 0)
 156                 goto out;
 157         ret = read_rsa_bignums(blob + ret, decoded_size - ret, &key->rsa);
 158         if (ret < 0)
 159                 goto free_blob;
 160         ret = RSA_size(key->rsa);
 161         assert(ret > 0);
 162         *result = key;
 163 free_blob:
 164         free(blob);
 165 out:
 166         if (ret < 0) {
 167                 free(key);
 168                 *result = NULL;
 169                 PARA_ERROR_LOG("can not load key %s\n", key_file);
 170         }
 171         return ret;
 172 }
 173
 174 void apc_free_pubkey(struct asymmetric_key *key)
 175 {
 176         if (!key)
 177                 return;
 178         RSA_free(key->rsa);
 179         free(key);
 180 }
 181
 182 int apc_priv_decrypt(const char *key_file, unsigned char *outbuf,
 183                 unsigned char *inbuf, int inlen)
 184 {
 185         struct asymmetric_key *priv;
 186         int ret;
 187
 188         ret = check_private_key_file(key_file);
 189         if (ret < 0)
 190                 return ret;
 191         if (inlen < 0)
 192                 return -E_RSA;
 193         priv = para_malloc(sizeof(*priv));
 194         ret = get_private_key(key_file, &priv->rsa);
 195         if (ret < 0) {
 196                 free(priv);
 197                 return ret;
 198         }
 199         /*
 200          * RSA is vulnerable to timing attacks. Generate a random blinding
 201          * factor to protect against this kind of attack.
 202          */
 203         ret = -E_BLINDING;
 204         if (RSA_blinding_on(priv->rsa, NULL) == 0)
 205                 goto out;
 206         ret = RSA_private_decrypt(inlen, inbuf, outbuf, priv->rsa,
 207                 RSA_PKCS1_OAEP_PADDING);
 208         RSA_blinding_off(priv->rsa);
 209         if (ret <= 0)
 210                 ret = -E_DECRYPT;
 211 out:
 212         RSA_free(priv->rsa);
 213         free(priv);
 214         return ret;
 215 }
 216
 217 int apc_pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
 218                 unsigned len, unsigned char *outbuf)
 219 {
 220         int ret, flen = len; /* RSA_public_encrypt expects a signed int */
 221
 222         if (flen < 0)
 223                 return -E_ENCRYPT;
 224         ret = RSA_public_encrypt(flen, inbuf, outbuf, pub->rsa,
 225                 RSA_PKCS1_OAEP_PADDING);
 226         return ret < 0? -E_ENCRYPT : ret;
 227 }
 228
 229 struct stream_cipher {
 230         EVP_CIPHER_CTX *aes;
 231 };
 232
 233 struct stream_cipher *sc_new(const unsigned char *data, int len)
 234 {
 235         struct stream_cipher *sc = para_malloc(sizeof(*sc));
 236
 237         assert(len >= 2 * AES_CRT128_BLOCK_SIZE);
 238         sc->aes = EVP_CIPHER_CTX_new();
 239         EVP_EncryptInit_ex(sc->aes, EVP_aes_128_ctr(), NULL, data,
 240                 data + AES_CRT128_BLOCK_SIZE);
 241         return sc;
 242 }
 243
 244 void sc_free(struct stream_cipher *sc)
 245 {
 246         if (!sc)
 247                 return;
 248         EVP_CIPHER_CTX_free(sc->aes);
 249         free(sc);
 250 }
 251
 252 static void aes_ctr128_crypt(EVP_CIPHER_CTX *ctx, struct iovec *src,
 253                 struct iovec *dst)
 254 {
 255         int ret, inlen = src->iov_len, outlen, tmplen;
 256
 257         *dst = (typeof(*dst)) {
 258                 /* Add one for the terminating zero byte. */
 259                 .iov_base = para_malloc(inlen + 1),
 260                 .iov_len = inlen
 261         };
 262         ret = EVP_EncryptUpdate(ctx, dst->iov_base, &outlen, src->iov_base, inlen);
 263         assert(ret != 0);
 264         ret = EVP_EncryptFinal_ex(ctx, dst->iov_base + outlen, &tmplen);
 265         assert(ret != 0);
 266         outlen += tmplen;
 267         ((char *)dst->iov_base)[outlen] = '\0';
 268         dst->iov_len = outlen;
 269 }
 270
 271 void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst)
 272 {
 273         return aes_ctr128_crypt(sc->aes, src, dst);
 274 }
 275
 276 void hash_function(const char *data, unsigned long len, unsigned char *hash)
 277 {
 278         SHA_CTX c;
 279         SHA1_Init(&c);
 280         SHA1_Update(&c, data, len);
 281         SHA1_Final(hash, &c);
 282 }