/*
- * Copyright (C) 2005-2011 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>
*
* Licensed under the GPL v2. For licencing details see COPYING.
*/
#include <openssl/rc4.h>
#include <openssl/pem.h>
#include <openssl/sha.h>
+#include <openssl/bn.h>
+#include <openssl/aes.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.
- *
- * \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;
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().
+/*
+ * Read 64 bytes from /dev/urandom and adds them to the SSL PRNG. Seed the PRNG
+ * used by random() with a random seed obtained from SSL. If /dev/random is not
+ * readable the function calls exit().
*
* \sa RAND_load_file(3), \ref get_random_bytes_or_die(), srandom(3),
* random(3), \ref para_random().
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 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)
+static int get_openssl_key(const char *key_file, RSA **rsa, int private)
{
- struct asymmetric_key *key;
- RSA *rsa;
- EVP_PKEY *pkey = load_key(key_file, private);
+ EVP_PKEY *key = load_key(key_file, private);
- if (!pkey)
+ if (!key)
return (private == LOAD_PRIVATE_KEY)? -E_PRIVATE_KEY
: -E_PUBLIC_KEY;
- rsa = EVP_PKEY_get1_RSA(pkey);
- EVP_PKEY_free(pkey);
- if (!rsa)
+ *rsa = EVP_PKEY_get1_RSA(key);
+ EVP_PKEY_free(key);
+ if (!*rsa)
return -E_RSA;
- key = para_malloc(sizeof(*key));
- key->rsa = rsa;
- *result = key;
- return RSA_size(rsa);
+ return RSA_size(*rsa);
}
-/**
- * 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().
+/*
+ * 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:
+ RSA_free(rsa);
+ return ret;
+}
+
+int get_asymmetric_key(const char *key_file, int private,
+ struct asymmetric_key **result)
+{
+ 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_unmap;
+ blob_size = 2 * map_size;
+ blob = para_malloc(blob_size);
+ ret = uudecode(cp, blob, blob_size);
+ if (ret < 0)
+ goto out_unmap;
+ decoded_size = ret;
+ ret = check_ssh_key_header(blob, decoded_size);
+ if (ret < 0)
+ goto out_unmap;
+ ret = read_rsa_bignums(blob + ret, decoded_size - ret, &key->rsa);
+ if (ret < 0)
+ goto out_unmap;
+ ret = RSA_size(key->rsa);
+out_unmap:
+ ret2 = para_munmap(map, map_size);
+ if (ret >= 0 && ret2 < 0)
+ ret = ret2;
+out:
+ 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;
+}
+
void free_asymmetric_key(struct asymmetric_key *key)
{
if (!key)
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.
- *
- * \return The size of the recovered plaintext on success, negative on errors.
- *
- * \sa RSA_private_decrypt(3)
- **/
int priv_decrypt(const char *key_file, unsigned char *outbuf,
unsigned char *inbuf, int inlen)
{
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)
{
return ret < 0? -E_ENCRYPT : ret;
}
-#define RC4_ALIGN 8
+struct aes_ctr_128_context {
+ AES_KEY key;
+ unsigned char ivec[AES_CRT128_BLOCK_SIZE];
+ unsigned char ecount[AES_CRT128_BLOCK_SIZE];
+ unsigned int num;
+};
+
struct stream_cipher {
- RC4_KEY key;
+ bool use_aes;
+ union {
+ RC4_KEY rc4_key;
+ struct aes_ctr_128_context aes;
+ } context;
};
-/**
- * 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 *sc_new(const unsigned char *data, int len)
+struct stream_cipher *sc_new(const unsigned char *data, int len,
+ bool use_aes)
{
+ int ret;
struct stream_cipher *sc = para_malloc(sizeof(*sc));
- RC4_set_key(&sc->key, len, data);
+ struct aes_ctr_128_context *aes;
+
+ sc->use_aes = use_aes;
+ if (!use_aes) {
+ RC4_set_key(&sc->context.rc4_key, len, data);
+ return sc;
+ }
+ assert(len >= 2 * AES_CRT128_BLOCK_SIZE);
+ aes = &sc->context.aes;
+ ret = AES_set_encrypt_key(data, AES_CRT128_BLOCK_SIZE * 8 /* bits */,
+ &aes->key);
+ assert(ret == 0);
+ memcpy(aes->ivec, data + AES_CRT128_BLOCK_SIZE, AES_CRT128_BLOCK_SIZE);
+ aes->num = 0;
return sc;
}
-/**
- * Deallocate a stream cipher structure.
- *
- * \param sc A stream cipher previously obtained by sc_new().
- */
void sc_free(struct stream_cipher *sc)
{
free(sc);
}
/**
- * Encrypt and send a buffer.
- *
- * \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().
- *
- * \sa \ref write_all(), RC4(3).
+ * 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.
*/
-int sc_send_bin_buffer(struct stream_cipher_context *scc, const char *buf,
- size_t len)
-{
- 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);
+#define RC4_ALIGN 8
- assert(len);
- tmp = para_malloc(l2);
- RC4(&scc->send->key, l1, (const unsigned char *)buf, tmp);
+static void rc4_crypt(RC4_KEY *key, struct iovec *src, struct iovec *dst)
+{
+ size_t len = src->iov_len, l1, l2;
+
+ assert(len > 0);
+ assert(len < ((typeof(src->iov_len))-1) / 2);
+ l1 = ROUND_DOWN(len, RC4_ALIGN);
+ l2 = ROUND_UP(len, RC4_ALIGN);
+
+ *dst = (typeof(*dst)) {
+ /* Add one for the terminating zero byte. */
+ .iov_base = para_malloc(l2 + 1),
+ .iov_len = len
+ };
+ RC4(key, l1, src->iov_base, dst->iov_base);
if (len > l1) {
- memcpy(remainder, buf + l1, len - l1);
- RC4(&scc->send->key, len - l1, remainder, tmp + l1);
+ unsigned char remainder[RC4_ALIGN] = "";
+ memcpy(remainder, src->iov_base + l1, len - l1);
+ RC4(key, len - l1, remainder, dst->iov_base + l1);
}
- ret = write_all(scc->fd, (char *)tmp, &len);
- free(tmp);
- return ret;
+ ((char *)dst->iov_base)[len] = '\0';
}
-/**
- * Encrypt and send a \p NULL-terminated buffer.
- *
- * \param scc The context.
- * \param buf The buffer to send.
- *
- * \return The return value of the underyling call to sc_send_bin_buffer().
- */
-int sc_send_buffer(struct stream_cipher_context *scc, const char *buf)
-{
- return sc_send_bin_buffer(scc, buf, strlen(buf));
-}
-
-/**
- * Format, encrypt and send a buffer.
- *
- * \param scc The context.
- * \param fmt A format string.
- *
- * \return The return value of the underyling call to sc_send_buffer().
- */
-__printf_2_3 int sc_send_va_buffer(struct stream_cipher_context *scc,
- const char *fmt, ...)
-{
- char *msg;
- int ret;
-
- PARA_VSPRINTF(fmt, msg);
- ret = sc_send_buffer(scc, msg);
- free(msg);
- return ret;
-}
-
-/**
- * Receive a buffer and decrypt it.
- *
- * \param scc The context.
- * \param buf The buffer to write the decrypted data to.
- * \param size The size of \a buf.
- *
- * \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 sc_recv_bin_buffer(struct stream_cipher_context *scc, char *buf,
- size_t size)
+static void aes_ctr128_crypt(struct aes_ctr_128_context *aes, struct iovec *src,
+ struct iovec *dst)
{
- unsigned char *tmp = para_malloc(size);
- ssize_t ret = recv(scc->fd, tmp, size, 0);
-
- if (ret > 0)
- RC4(&scc->recv->key, ret, tmp, (unsigned char *)buf);
- else if (ret < 0)
- ret = -ERRNO_TO_PARA_ERROR(errno);
- free(tmp);
- return ret;
+ size_t len = src->iov_len;
+
+ *dst = (typeof(*dst)) {
+ /* Add one for the terminating zero byte. */
+ .iov_base = para_malloc(len + 1),
+ .iov_len = len
+ };
+ AES_ctr128_encrypt(src->iov_base, dst->iov_base, len,
+ &aes->key, aes->ivec, aes->ecount, &aes->num);
+ ((char *)dst->iov_base)[len] = '\0';
}
-/**
- * Receive a buffer, decrypt it and write terminating NULL byte.
- *
- * \param scc The 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 scc, 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
- * sc_recv_bin_buffer().
- */
-int sc_recv_buffer(struct stream_cipher_context *scc, char *buf, size_t size)
+void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst)
{
- int n;
-
- assert(size);
- n = sc_recv_bin_buffer(scc, buf, size - 1);
- if (n >= 0)
- buf[n] = '\0';
- else
- *buf = '\0';
- return n;
+ if (sc->use_aes)
+ return aes_ctr128_crypt(&sc->context.aes, src, dst);
+ return rc4_crypt(&sc->context.rc4_key, src, dst);
}
-/**
- * Compute the hash of the given input data.
- *
- * \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.
- *
- * \a hash must point to an area at least \p HASH_SIZE bytes large.
- *
- * \sa sha(3), openssl(1).
- * */
void hash_function(const char *data, unsigned long len, unsigned char *hash)
{
SHA_CTX c;
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