X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=crypt.c;h=1678977a4502a008a695843b5e56a0e9a4bc6a79;hp=cdcb6149d04254a0def3bcc903823f71ae3a89e5;hb=3a6b996d8b39fdc067df352d1eee757ef2a8f49b;hpb=92e4a0579a320372d2e94efc7c2a0d9f419e3ffe

diff --git a/crypt.c b/crypt.c
index cdcb6149..1678977a 100644
--- a/crypt.c
+++ b/crypt.c
@@ -1,35 +1,33 @@
 /*
- * Copyright (C) 2005-2011 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2005-2014 Andre Noll <maan@tuebingen.mpg.de>
  *
  * 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 <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"
-/**
- * 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().
- */
+#include "crypt_backend.h"
+
+struct asymmetric_key {
+	RSA *rsa;
+};
+
 void get_random_bytes_or_die(unsigned char *buf, int num)
 {
 	unsigned long err;
@@ -42,13 +40,10 @@ void get_random_bytes_or_die(unsigned char *buf, int num)
 	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().
@@ -65,19 +60,6 @@ void init_random_seed_or_die(void)
 	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;
@@ -101,18 +83,7 @@ static EVP_PKEY *load_key(const char *file, int private)
 	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);
 
@@ -126,42 +97,138 @@ int get_rsa_key(char *key_file, RSA **rsa, int private)
 	return RSA_size(*rsa);
 }
 
-/**
- * free an RSA structure
- *
- * \param rsa pointer to the RSA struct to free
- *
- * This must be called for any key obtained by get_rsa_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.
  */
-void rsa_free(RSA *rsa)
+
+static int read_bignum(const unsigned char *buf, size_t len, BIGNUM **result)
 {
-	if (rsa)
-		RSA_free(rsa);
+	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;
 }
 
-/**
- * decrypt a buffer using an RSA 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
- *
- * 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 para_decrypt_buffer(char *key_file, unsigned char *outbuf, unsigned char *inbuf,
-			unsigned rsa_inlen)
+static int read_rsa_bignums(const unsigned char *blob, int blen, RSA **result)
 {
+	int ret;
 	RSA *rsa;
-	int ret, inlen = rsa_inlen;
+	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)
+		return;
+	RSA_free(key->rsa);
+	free(key);
+}
+
+int priv_decrypt(const char *key_file, unsigned char *outbuf,
+		unsigned char *inbuf, int 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;
 	/*
@@ -169,152 +236,128 @@ int para_decrypt_buffer(char *key_file, unsigned char *outbuf, unsigned char *in
 	 * 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
- *
- * \param rsa: public rsa 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 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;
 }
 
-#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;
+};
 
-/**
- * Encrypt and send a buffer.
- *
- * \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().
- *
- * \sa \ref write_all(), RC4(3).
- */
-int rc4_send_bin_buffer(struct rc4_context *rc4c, const char *buf, size_t len)
+struct stream_cipher {
+	bool use_aes;
+	union {
+		RC4_KEY rc4_key;
+		struct aes_ctr_128_context aes;
+	} context;
+};
+
+struct stream_cipher *sc_new(const unsigned char *data, int len,
+		bool use_aes)
 {
 	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);
+	struct stream_cipher *sc = para_malloc(sizeof(*sc));
+	struct aes_ctr_128_context *aes;
 
-	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);
+	sc->use_aes = use_aes;
+	if (!use_aes) {
+		RC4_set_key(&sc->context.rc4_key, len, data);
+		return sc;
 	}
-	ret = write_all(rc4c->fd, (char *)tmp, &len);
-	free(tmp);
-	return ret;
+	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;
 }
 
-/**
- * Encrypt and send a \p NULL-terminated buffer.
- *
- * \param rc4c The rc4 crypt context.
- * \param buf The buffer to send.
- *
- * \return The return value of the underyling call to rc4_send_bin_buffer().
- */
-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.
- *
- * \param rc4c The rc4 crypt context.
- * \param fmt A format string.
- *
- * \return The return value of the underyling call to rc4_send_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.
  */
-__printf_2_3 int rc4_send_va_buffer(struct rc4_context *rc4c, const char *fmt, ...)
+#define RC4_ALIGN 8
+
+static void rc4_crypt(RC4_KEY *key, struct iovec *src, struct iovec *dst)
 {
-	char *msg;
-	int ret;
+	size_t len = src->iov_len, l1, l2;
 
-	PARA_VSPRINTF(fmt, msg);
-	ret = rc4_send_buffer(rc4c, msg);
-	free(msg);
-	return ret;
+	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) {
+		unsigned char remainder[RC4_ALIGN] = "";
+		memcpy(remainder, src->iov_base + l1, len - l1);
+		RC4(key, len - l1, remainder, dst->iov_base + l1);
+	}
+	((char *)dst->iov_base)[len] = '\0';
 }
 
-/**
- * Receive a buffer and decrypt it.
- *
- * \param rc4c The rc4 crypt 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 rc4_recv_bin_buffer(struct rc4_context *rc4c, 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(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;
+	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 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)
+void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst)
+{
+	if (sc->use_aes)
+		return aes_ctr128_crypt(&sc->context.aes, src, dst);
+	return rc4_crypt(&sc->context.rc4_key, src, dst);
+}
+
+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);
 }