/*
- * Copyright (C) 2005-2009 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2005-2011 Andre Noll <maan@systemlinux.org>
*
* 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 <stdbool.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 <openssl/sha.h>
+#include <openssl/bn.h>
#include "para.h"
#include "error.h"
#include "string.h"
#include "crypt.h"
#include "fd.h"
+#include "crypt_backend.h"
+
+struct asymmetric_key {
+ RSA *rsa;
+};
+
/**
* Fill a buffer with random content.
*
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;
return pkey;
}
-/**
- * read an RSA key from a file
- *
- * \param key_file the file containing the key
- * \param rsa RSA structure is returned here
- * \param private if non-zero, read the private key, otherwise the public key
- *
- * \return The size of the RSA key on success, negative on errors.
- *
- * \sa openssl(1), rsa(1).
- */
-int get_rsa_key(char *key_file, RSA **rsa, int private)
+static int get_openssl_key(const char *key_file, RSA **rsa, int private)
{
EVP_PKEY *key = load_key(key_file, private);
return RSA_size(*rsa);
}
+/*
+ * The public key loading functions below were inspired by corresponding code
+ * of openssh-5.2p1, Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo,
+ * Finland. However, not much of the original code remains.
+ */
+
+static int read_bignum(const unsigned char *buf, size_t len, BIGNUM **result)
+{
+ const unsigned char *p = buf, *end = buf + len;
+ uint32_t bnsize;
+ BIGNUM *bn;
+
+ if (p + 4 < p)
+ return -E_BIGNUM;
+ if (p + 4 > end)
+ return -E_BIGNUM;
+ bnsize = read_ssh_u32(p);
+ PARA_DEBUG_LOG("bnsize: %u\n", bnsize);
+ p += 4;
+ if (p + bnsize < p)
+ return -E_BIGNUM;
+ if (p + bnsize > end)
+ return -E_BIGNUM;
+ if (bnsize > 8192)
+ return -E_BIGNUM;
+ bn = BN_bin2bn(p, bnsize, NULL);
+ if (!bn)
+ return -E_BIGNUM;
+ *result = bn;
+ return bnsize + 4;
+}
+
+static int read_rsa_bignums(const unsigned char *blob, int blen, RSA **result)
+{
+ int ret;
+ RSA *rsa;
+ const unsigned char *p = blob, *end = blob + blen;
+
+ rsa = RSA_new();
+ if (!rsa)
+ return -E_BIGNUM;
+ ret = read_bignum(p, end - p, &rsa->e);
+ if (ret < 0)
+ goto fail;
+ p += ret;
+ ret = read_bignum(p, end - p, &rsa->n);
+ if (ret < 0)
+ goto fail;
+ *result = rsa;
+ return 1;
+fail:
+ if (rsa)
+ RSA_free(rsa);
+ return ret;
+}
+
/**
- * free an RSA structure
+ * 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.
*
- * \param rsa pointer to the RSA struct to free
+ * \return The size of the key on success, negative on errors.
*
- * This must be called for any key obtained by get_rsa_key().
+ * \sa openssl(1), rsa(1).
*/
-void rsa_free(RSA *rsa)
+int get_asymmetric_key(const char *key_file, int private,
+ struct asymmetric_key **result)
{
- if (rsa)
- RSA_free(rsa);
+ struct asymmetric_key *key = NULL;
+ void *map = NULL;
+ unsigned char *blob = NULL;
+ size_t map_size, blob_size, decoded_size;
+ int ret, ret2;
+ char *cp;
+
+ key = para_malloc(sizeof(*key));
+ if (private) {
+ ret = get_openssl_key(key_file, &key->rsa, LOAD_PRIVATE_KEY);
+ goto out;
+ }
+ ret = mmap_full_file(key_file, O_RDONLY, &map, &map_size, NULL);
+ if (ret < 0)
+ goto out;
+ ret = is_ssh_rsa_key(map, map_size);
+ if (!ret) {
+ ret = para_munmap(map, map_size);
+ map = NULL;
+ if (ret < 0)
+ goto out;
+ ret = get_openssl_key(key_file, &key->rsa, LOAD_PUBLIC_KEY);
+ goto out;
+ }
+ cp = map + ret;
+ PARA_INFO_LOG("decoding public rsa-ssh key %s\n", key_file);
+ ret = -ERRNO_TO_PARA_ERROR(EOVERFLOW);
+ if (map_size > INT_MAX / 4)
+ goto out;
+ blob_size = 2 * map_size;
+ blob = para_malloc(blob_size);
+ ret = uudecode(cp, blob, blob_size);
+ if (ret < 0)
+ goto out;
+ decoded_size = ret;
+ ret = check_ssh_key_header(blob, decoded_size);
+ if (ret < 0)
+ goto out;
+ ret = read_rsa_bignums(blob + ret, decoded_size - ret, &key->rsa);
+ if (ret < 0)
+ goto out;
+ ret = RSA_size(key->rsa);
+out:
+ ret2 = para_munmap(map, map_size);
+ if (ret >= 0 && ret2 < 0)
+ ret = ret2;
+ if (ret < 0) {
+ free(key);
+ result = NULL;
+ PARA_ERROR_LOG("key %s: %s\n", key_file, para_strerror(-ret));
+ } else
+ *result = key;
+ free(blob);
+ return ret;
+}
+
+/**
+ * Deallocate an asymmetric key structure.
+ *
+ * \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 an RSA key
+ * Decrypt a buffer using a private key.
*
- * \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_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,
- unsigned rsa_inlen)
+int priv_decrypt(const char *key_file, unsigned char *outbuf,
+ unsigned char *inbuf, int inlen)
{
- RSA *rsa;
- int ret, inlen = rsa_inlen;
+ struct asymmetric_key *priv;
+ int ret;
if (inlen < 0)
return -E_RSA;
- ret = get_rsa_key(key_file, &rsa, LOAD_PRIVATE_KEY);
+ ret = get_asymmetric_key(key_file, LOAD_PRIVATE_KEY, &priv);
if (ret < 0)
return ret;
/*
* factor to protect against this kind of attack.
*/
ret = -E_BLINDING;
- if (RSA_blinding_on(rsa, NULL) == 0)
+ if (RSA_blinding_on(priv->rsa, NULL) == 0)
goto out;
- ret = RSA_private_decrypt(inlen, inbuf, outbuf, rsa, RSA_PKCS1_OAEP_PADDING);
- RSA_blinding_off(rsa);
+ 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:
- rsa_free(rsa);
+ free_asymmetric_key(priv);
return ret;
}
/**
- * encrypt a buffer using an RSA key
+ * 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
+ * \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
+ * \return The size of the encrypted data on success, negative on errors.
*
* \sa RSA_public_encrypt(3)
*/
-int para_encrypt_buffer(RSA *rsa, unsigned char *inbuf,
+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, rsa, RSA_PKCS1_OAEP_PADDING);
+ ret = RSA_public_encrypt(flen, inbuf, outbuf, pub->rsa,
+ RSA_PKCS1_OAEP_PADDING);
return ret < 0? -E_ENCRYPT : ret;
}
+struct stream_cipher {
+ RC4_KEY key;
+};
+
/**
- * Encrypt and send a buffer.
+ * Allocate and initialize a stream cipher structure.
*
- * \param rc4c The rc4 crypt context.
- * \param buf The buffer to send.
- * \param len The size of \a buf in bytes.
- *
- * \return The return value of the underyling call to write_all().
+ * \param data The key.
+ * \param len The size of the key.
*
- * \sa \ref write_all(), RC4(3).
+ * \return A new stream cipher structure.
*/
-int rc4_send_bin_buffer(struct rc4_context *rc4c, const char *buf, size_t len)
+struct stream_cipher *sc_new(const unsigned char *data, int len)
{
- int ret;
- unsigned char *tmp;
-
- assert(len);
- tmp = para_malloc(len);
- RC4(&rc4c->send_key, len, (const unsigned char *)buf, tmp);
- ret = write_all(rc4c->fd, (char *)tmp, &len);
- free(tmp);
- return ret;
+ struct stream_cipher *sc = para_malloc(sizeof(*sc));
+ RC4_set_key(&sc->key, len, data);
+ return sc;
}
/**
- * Encrypt and send a \p NULL-terminated buffer.
- *
- * \param rc4c The rc4 crypt context.
- * \param buf The buffer to send.
+ * Deallocate a stream cipher structure.
*
- * \return The return value of the underyling call to rc4_send_bin_buffer().
+ * \param sc A stream cipher previously obtained by sc_new().
*/
-int rc4_send_buffer(struct rc4_context *rc4c, const char *buf)
+void sc_free(struct stream_cipher *sc)
{
- return rc4_send_bin_buffer(rc4c, buf, strlen(buf));
+ free(sc);
}
/**
- * Format, encrypt and send a buffer.
+ * The RC4() implementation of openssl apparently reads and writes data in
+ * blocks of 8 bytes. So we have to make sure our buffer sizes are a multiple
+ * of this.
+ */
+#define RC4_ALIGN 8
+
+/**
+ * Encrypt and send a buffer.
*
- * \param rc4c The rc4 crypt context.
- * \param fmt A format string.
+ * \param scc The context.
+ * \param buf The buffer to send.
+ * \param len The size of \a buf in bytes.
+ *
+ * \return The return value of the underyling call to write_all().
*
- * \return The return value of the underyling call to rc4_send_buffer().
+ * \sa \ref write_all(), RC4(3).
*/
-__printf_2_3 int rc4_send_va_buffer(struct rc4_context *rc4c, const char *fmt, ...)
+int sc_send_bin_buffer(struct stream_cipher_context *scc, const char *buf,
+ size_t len)
{
- char *msg;
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);
- PARA_VSPRINTF(fmt, msg);
- ret = rc4_send_buffer(rc4c, msg);
- free(msg);
+ assert(len);
+ tmp = para_malloc(l2);
+ RC4(&scc->send->key, l1, (const unsigned char *)buf, tmp);
+ if (len > l1) {
+ memcpy(remainder, buf + l1, len - l1);
+ RC4(&scc->send->key, len - l1, remainder, tmp + l1);
+ }
+ ret = write_all(scc->fd, (char *)tmp, &len);
+ free(tmp);
return ret;
}
/**
* Receive a buffer and decrypt it.
*
- * \param rc4c The rc4 crypt context.
+ * \param scc The context.
* \param buf The buffer to write the decrypted data to.
* \param size The size of \a buf.
*
*
* \sa recv(2), RC4(3).
*/
-int rc4_recv_bin_buffer(struct rc4_context *rc4c, char *buf, size_t size)
+int sc_recv_bin_buffer(struct stream_cipher_context *scc, char *buf,
+ size_t size)
{
unsigned char *tmp = para_malloc(size);
- ssize_t ret = recv(rc4c->fd, tmp, size, 0);
+ ssize_t ret = recv(scc->fd, tmp, size, 0);
if (ret > 0)
- RC4(&rc4c->recv_key, ret, tmp, (unsigned char *)buf);
+ RC4(&scc->recv->key, ret, tmp, (unsigned char *)buf);
else if (ret < 0)
ret = -ERRNO_TO_PARA_ERROR(errno);
free(tmp);
}
/**
- * Receive a buffer, decrypt it and write terminating NULL byte.
+ * Compute the hash of the given input data.
*
- * \param rc4c The rc4 crypt context.
- * \param buf The buffer to write the decrypted data to.
- * \param size The size of \a buf.
+ * \param data Pointer to the data to compute the hash value from.
+ * \param len The length of \a data in bytes.
+ * \param hash Result pointer.
*
- * 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.
+ * \a hash must point to an area at least \p HASH_SIZE bytes large.
*
- * \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)
+ * \sa sha(3), openssl(1).
+ * */
+void hash_function(const char *data, unsigned long len, unsigned char *hash)
{
- int n;
-
- assert(size);
- n = rc4_recv_bin_buffer(rc4c, buf, size - 1);
- if (n >= 0)
- buf[n] = '\0';
- else
- *buf = '\0';
- return n;
+ SHA_CTX c;
+ SHA1_Init(&c);
+ SHA1_Update(&c, data, len);
+ SHA1_Final(hash, &c);
}
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