/*
- * Copyright (C) 2005-2006 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2005-2011 Andre Noll <maan@systemlinux.org>
*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
+ * Licensed under the GPL v2. For licencing details see COPYING.
*/
-/** \file crypt.c openssl-based RSA encryption/decryption routines */
+/** \file crypt.c Openssl-based encryption/decryption routines. */
+
+#include <regex.h>
+#include <dirent.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <openssl/rand.h>
+#include <openssl/err.h>
+#include <openssl/rc4.h>
+#include <openssl/pem.h>
#include "para.h"
#include "error.h"
#include "string.h"
#include "crypt.h"
+#include "fd.h"
+
+struct asymmetric_key {
+ RSA *rsa;
+};
+
+/**
+ * Fill a buffer with random content.
+ *
+ * \param buf The buffer to fill.
+ * \param num The size of \a buf in bytes.
+ *
+ * This function puts \a num cryptographically strong pseudo-random bytes into
+ * buf. If libssl can not guarantee an unpredictable byte sequence (for example
+ * because the PRNG has not been seeded with enough randomness) the function
+ * logs an error message and calls exit().
+ */
+void get_random_bytes_or_die(unsigned char *buf, int num)
+{
+ unsigned long err;
+
+ /* RAND_bytes() returns 1 on success, 0 otherwise. */
+ if (RAND_bytes(buf, num) == 1)
+ return;
+ err = ERR_get_error();
+ PARA_EMERG_LOG("%s\n", ERR_reason_error_string(err));
+ exit(EXIT_FAILURE);
+}
+
+/**
+ * Seed pseudo random number generators.
+ *
+ * This function reads 64 bytes from /dev/urandom and adds them to the SSL
+ * PRNG. It also seeds the PRNG used by random() with a random seed obtained
+ * from SSL. If /dev/random could not be read, an error message is logged and
+ * the function calls exit().
+ *
+ * \sa RAND_load_file(3), \ref get_random_bytes_or_die(), srandom(3),
+ * random(3), \ref para_random().
+ */
+void init_random_seed_or_die(void)
+{
+ int seed, ret = RAND_load_file("/dev/urandom", 64);
+
+ if (ret != 64) {
+ PARA_EMERG_LOG("could not seed PRNG (ret = %d)\n", ret);
+ exit(EXIT_FAILURE);
+ }
+ get_random_bytes_or_die((unsigned char *)&seed, sizeof(seed));
+ srandom(seed);
+}
+
+static int check_key_file(const char *file, int private)
+{
+ struct stat st;
+
+ if (stat(file, &st) != 0)
+ return -ERRNO_TO_PARA_ERROR(errno);
+ if (private != LOAD_PRIVATE_KEY)
+ return 0;
+ if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0)
+ return -E_KEY_PERM;
+ return 1;
+}
static EVP_PKEY *load_key(const char *file, int private)
{
BIO *key;
EVP_PKEY *pkey = NULL;
+ int ret = check_key_file(file, private);
+ if (ret < 0) {
+ PARA_ERROR_LOG("%s\n", para_strerror(-ret));
+ return NULL;
+ }
key = BIO_new(BIO_s_file());
if (!key)
return NULL;
return pkey;
}
-
-int get_rsa_key(char *key_file, RSA **rsa, int private)
+/**
+ * Read an asymmetric key from a file.
+ *
+ * \param key_file The file containing the key.
+ * \param private if non-zero, read the private key, otherwise the public key.
+ * \param result The key structure is returned here.
+ *
+ * \return The size of the key on success, negative on errors.
+ *
+ * \sa openssl(1), rsa(1).
+ */
+int get_asymmetric_key(const char *key_file, int private,
+ struct asymmetric_key **result)
{
- EVP_PKEY *key = load_key(key_file, private);
+ struct asymmetric_key *key;
+ RSA *rsa;
+ EVP_PKEY *pkey = load_key(key_file, private);
- if (!key)
- return (private == LOAD_PRIVATE_KEY)? -E_PRIVATE_KEY : -E_PUBLIC_KEY;
- *rsa = EVP_PKEY_get1_RSA(key);
- EVP_PKEY_free(key);
- if (!*rsa)
+ if (!pkey)
+ return (private == LOAD_PRIVATE_KEY)? -E_PRIVATE_KEY
+ : -E_PUBLIC_KEY;
+ rsa = EVP_PKEY_get1_RSA(pkey);
+ EVP_PKEY_free(pkey);
+ if (!rsa)
return -E_RSA;
- return RSA_size(*rsa);
+ key = para_malloc(sizeof(*key));
+ key->rsa = rsa;
+ *result = key;
+ return RSA_size(rsa);
}
/**
- * decrypt a buffer using an RSA key
+ * Deallocate an asymmetric key structure.
*
- * \param key_file full path of the rsa key
- * \param outbuf the output buffer
- * \param inbuf the encrypted input buffer
- * \param rsa_inlen the length of \a inbuf
+ * \param key Pointer to the key structure to free.
+ *
+ * This must be called for any key obtained by get_asymmetric_key().
+ */
+void free_asymmetric_key(struct asymmetric_key *key)
+{
+ if (!key)
+ return;
+ RSA_free(key->rsa);
+ free(key);
+}
+
+/**
+ * Decrypt a buffer using a private key.
+ *
+ * \param key_file Full path of the key.
+ * \param outbuf The output buffer.
+ * \param inbuf The encrypted input buffer.
+ * \param inlen The length of \a inbuf in bytes.
*
* The \a outbuf must be large enough to hold at least \a rsa_inlen bytes.
*
*
* \sa RSA_private_decrypt(3)
**/
-int para_decrypt_buffer(char *key_file, unsigned char *outbuf, unsigned char *inbuf,
- int rsa_inlen)
+int priv_decrypt(const char *key_file, unsigned char *outbuf,
+ unsigned char *inbuf, int inlen)
{
- RSA *rsa;
- int ret = get_rsa_key(key_file, &rsa, LOAD_PRIVATE_KEY);
+ struct asymmetric_key *priv;
+ int ret;
+ if (inlen < 0)
+ return -E_RSA;
+ ret = get_asymmetric_key(key_file, LOAD_PRIVATE_KEY, &priv);
if (ret < 0)
return ret;
- ret = RSA_private_decrypt(rsa_inlen, inbuf, outbuf, rsa, RSA_PKCS1_PADDING);
- return (ret > 0)? ret : -E_DECRYPT;
+ /*
+ * RSA is vulnerable to timing attacks. Generate a random blinding
+ * factor to protect against this kind of attack.
+ */
+ ret = -E_BLINDING;
+ if (RSA_blinding_on(priv->rsa, NULL) == 0)
+ goto out;
+ ret = RSA_private_decrypt(inlen, inbuf, outbuf, priv->rsa,
+ RSA_PKCS1_OAEP_PADDING);
+ RSA_blinding_off(priv->rsa);
+ if (ret <= 0)
+ ret = -E_DECRYPT;
+out:
+ free_asymmetric_key(priv);
+ return ret;
+}
+
+/**
+ * Encrypt a buffer using an RSA key
+ *
+ * \param pub: The public key.
+ * \param inbuf The input buffer.
+ * \param len The length of \a inbuf.
+ * \param outbuf The output buffer.
+ *
+ * \return The size of the encrypted data on success, negative on errors.
+ *
+ * \sa RSA_public_encrypt(3)
+ */
+int pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
+ unsigned len, unsigned char *outbuf)
+{
+ int ret, flen = len; /* RSA_public_encrypt expects a signed int */
+
+ if (flen < 0)
+ return -E_ENCRYPT;
+ ret = RSA_public_encrypt(flen, inbuf, outbuf, pub->rsa,
+ RSA_PKCS1_OAEP_PADDING);
+ return ret < 0? -E_ENCRYPT : ret;
+}
+
+#define RC4_ALIGN 8
+struct stream_cipher {
+ RC4_KEY key;
+};
+
+/**
+ * Allocate and initialize a stream cipher structure.
+ *
+ * \param data The key.
+ * \param len The size of the key.
+ *
+ * \return A new stream cipher structure.
+ */
+struct stream_cipher *stream_cipher_new(const unsigned char *data, int len)
+{
+ struct stream_cipher *sc = para_malloc(sizeof(*sc));
+ RC4_set_key(&sc->key, len, data);
+ return sc;
+}
+
+/**
+ * Deallocate a stream cipher structure.
+ *
+ * \param sc A stream cipher previously obtained by stream_cipher_new().
+ */
+void stream_cipher_free(struct stream_cipher *sc)
+{
+ free(sc);
}
/**
- * decrypt the challenge number sent by para_server
+ * Encrypt and send a buffer.
*
- * \param key_file full path of the rsa key
- * \param challenge_nr result is stored here
- * \param inbuf the input buffer
- * \param rsa_inlen the length of \a inbuf
+ * \param rc4c The rc4 crypt context.
+ * \param buf The buffer to send.
+ * \param len The size of \a buf in bytes.
*
- * \return positive on success, negative on errors
+ * \return The return value of the underyling call to write_all().
*
- * \sa para_decrypt_buffer()
+ * \sa \ref write_all(), RC4(3).
*/
-int para_decrypt_challenge(char *key_file, long unsigned *challenge_nr,
- unsigned char *inbuf, int rsa_inlen)
+int rc4_send_bin_buffer(struct rc4_context *rc4c, const char *buf, size_t len)
{
- unsigned char *rsa_out = OPENSSL_malloc(rsa_inlen + 1);
- int ret = para_decrypt_buffer(key_file, rsa_out, inbuf, rsa_inlen);
+ int ret;
+ unsigned char *tmp;
+ static unsigned char remainder[RC4_ALIGN];
+ size_t l1 = ROUND_DOWN(len, RC4_ALIGN), l2 = ROUND_UP(len, RC4_ALIGN);
- if (ret >= 0) {
- rsa_out[ret] = '\0';
- ret = sscanf((char *)rsa_out, "%lu", challenge_nr) == 1?
- 1 : -E_CHALLENGE;
+ assert(len);
+ tmp = para_malloc(l2);
+ RC4(&rc4c->send->key, l1, (const unsigned char *)buf, tmp);
+ if (len > l1) {
+ memcpy(remainder, buf + l1, len - l1);
+ RC4(&rc4c->send->key, len - l1, remainder, tmp + l1);
}
- OPENSSL_free(rsa_out);
+ ret = write_all(rc4c->fd, (char *)tmp, &len);
+ free(tmp);
return ret;
}
/**
- * encrypt a buffer using an RSA key
- *
- * \param rsa: public rsa key
- * \param inbuf the input buffer
- * \param len the length of \a inbuf
- * \param outbuf the output buffer
+ * Encrypt and send a \p NULL-terminated buffer.
*
- * \return The size of the encrypted data on success, negative on errors
+ * \param rc4c The rc4 crypt context.
+ * \param buf The buffer to send.
*
- * \sa RSA_public_encrypt(3)
+ * \return The return value of the underyling call to rc4_send_bin_buffer().
*/
-int para_encrypt_buffer(RSA *rsa, unsigned char *inbuf,
- const unsigned len, unsigned char *outbuf)
+int rc4_send_buffer(struct rc4_context *rc4c, const char *buf)
{
- int ret = RSA_public_encrypt(len, inbuf, outbuf, rsa,
- RSA_PKCS1_PADDING);
- return ret < 0? -E_ENCRYPT : ret;
+ return rc4_send_bin_buffer(rc4c, buf, strlen(buf));
}
/**
- * encrypt the given challenge number
+ * Format, encrypt and send a buffer.
*
- * \param rsa: public rsa key
- * \param challenge_nr the number to be encrypted
- * \param outbuf the output buffer
+ * \param rc4c The rc4 crypt context.
+ * \param fmt A format string.
*
- * \a outbuf must be at least 64 bytes long
+ * \return The return value of the underyling call to rc4_send_buffer().
+ */
+__printf_2_3 int rc4_send_va_buffer(struct rc4_context *rc4c, const char *fmt, ...)
+{
+ char *msg;
+ int ret;
+
+ PARA_VSPRINTF(fmt, msg);
+ ret = rc4_send_buffer(rc4c, msg);
+ free(msg);
+ return ret;
+}
+
+/**
+ * Receive a buffer and decrypt it.
*
- * \return The size of the encrypted data on success, negative on errors
+ * \param rc4c The rc4 crypt context.
+ * \param buf The buffer to write the decrypted data to.
+ * \param size The size of \a buf.
*
- * \sa para_encrypt_buffer()
+ * \return The number of bytes received on success, negative on errors, zero if
+ * the peer has performed an orderly shutdown.
*
+ * \sa recv(2), RC4(3).
*/
-int para_encrypt_challenge(RSA* rsa, long unsigned challenge_nr,
- unsigned char *outbuf)
+int rc4_recv_bin_buffer(struct rc4_context *rc4c, char *buf, size_t size)
{
- unsigned char *inbuf = (unsigned char*) make_message("%lu", challenge_nr);
- int ret = para_encrypt_buffer(rsa, inbuf, strlen((char *)inbuf), outbuf);
- free(inbuf);
+ unsigned char *tmp = para_malloc(size);
+ ssize_t ret = recv(rc4c->fd, tmp, size, 0);
+
+ if (ret > 0)
+ RC4(&rc4c->recv->key, ret, tmp, (unsigned char *)buf);
+ else if (ret < 0)
+ ret = -ERRNO_TO_PARA_ERROR(errno);
+ free(tmp);
return ret;
}
+/**
+ * Receive a buffer, decrypt it and write terminating NULL byte.
+ *
+ * \param rc4c The rc4 crypt context.
+ * \param buf The buffer to write the decrypted data to.
+ * \param size The size of \a buf.
+ *
+ * Read at most \a size - 1 bytes from file descriptor given by \a rc4c,
+ * decrypt the received data and write a NULL byte at the end of the decrypted
+ * data.
+ *
+ * \return The return value of the underlying call to \ref
+ * rc4_recv_bin_buffer().
+ */
+int rc4_recv_buffer(struct rc4_context *rc4c, char *buf, size_t size)
+{
+ int n;
+
+ assert(size);
+ n = rc4_recv_bin_buffer(rc4c, buf, size - 1);
+ if (n >= 0)
+ buf[n] = '\0';
+ else
+ *buf = '\0';
+ return n;
+}
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