cipher.c - third_party/openssh-portable - Git at Google

 /* $OpenBSD: cipher.c,v 1.111 2018/02/23 15:58:37 markus Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
  *
  * As far as I am concerned, the code I have written for this software
  * can be used freely for any purpose.  Any derived versions of this
  * software must be clearly marked as such, and if the derived work is
  * incompatible with the protocol description in the RFC file, it must be
  * called by a name other than "ssh" or "Secure Shell".
  *
  *
  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  * Copyright (c) 1999, 2000 Markus Friedl.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "includes.h"

 #include <sys/types.h>

 #include <string.h>
 #include <stdarg.h>
 #include <stdio.h>

 #include "cipher.h"
 #include "misc.h"
 #include "sshbuf.h"
 #include "ssherr.h"
 #include "digest.h"

 #include "openbsd-compat/openssl-compat.h"


 struct sshcipher_ctx {
 	int	plaintext;
 	int	encrypt;
 	EVP_CIPHER_CTX *evp;
 	struct chachapoly_ctx cp_ctx; /* XXX union with evp? */
 	struct aesctr_ctx ac_ctx; /* XXX union with evp? */
 	const struct sshcipher *cipher;
 };

 struct sshcipher {
 	char	*name;
 	u_int	block_size;
 	u_int	key_len;
 	u_int	iv_len;		/* defaults to block_size */
 	u_int	auth_len;
 	u_int	flags;
 #define CFLAG_CBC		(1<<0)
 #define CFLAG_CHACHAPOLY	(1<<1)
 #define CFLAG_AESCTR		(1<<2)
 #define CFLAG_NONE		(1<<3)
 #define CFLAG_INTERNAL		CFLAG_NONE /* Don't use "none" for packets */
 #ifdef WITH_OPENSSL
 	const EVP_CIPHER	*(*evptype)(void);
 #else
 	void	*ignored;
 #endif
 };

 static const struct sshcipher ciphers[] = {
 #ifdef WITH_OPENSSL
 #ifndef OPENSSL_NO_DES
 	{ "3des-cbc",		8, 24, 0, 0, CFLAG_CBC, EVP_des_ede3_cbc },
 #endif
 	{ "aes128-cbc",		16, 16, 0, 0, CFLAG_CBC, EVP_aes_128_cbc },
 	{ "aes192-cbc",		16, 24, 0, 0, CFLAG_CBC, EVP_aes_192_cbc },
 	{ "aes256-cbc",		16, 32, 0, 0, CFLAG_CBC, EVP_aes_256_cbc },
 	{ "rijndael-cbc@lysator.liu.se",
 				16, 32, 0, 0, CFLAG_CBC, EVP_aes_256_cbc },
 	{ "aes128-ctr",		16, 16, 0, 0, 0, EVP_aes_128_ctr },
 	{ "aes192-ctr",		16, 24, 0, 0, 0, EVP_aes_192_ctr },
 	{ "aes256-ctr",		16, 32, 0, 0, 0, EVP_aes_256_ctr },
 # ifdef OPENSSL_HAVE_EVPGCM
 	{ "aes128-gcm@openssh.com",
 				16, 16, 12, 16, 0, EVP_aes_128_gcm },
 	{ "aes256-gcm@openssh.com",
 				16, 32, 12, 16, 0, EVP_aes_256_gcm },
 # endif /* OPENSSL_HAVE_EVPGCM */
 #else
 	{ "aes128-ctr",		16, 16, 0, 0, CFLAG_AESCTR, NULL },
 	{ "aes192-ctr",		16, 24, 0, 0, CFLAG_AESCTR, NULL },
 	{ "aes256-ctr",		16, 32, 0, 0, CFLAG_AESCTR, NULL },
 #endif
 	{ "chacha20-poly1305@openssh.com",
 				8, 64, 0, 16, CFLAG_CHACHAPOLY, NULL },
 	{ "none",		8, 0, 0, 0, CFLAG_NONE, NULL },

 	{ NULL,			0, 0, 0, 0, 0, NULL }
 };

 /*--*/

 /* Returns a comma-separated list of supported ciphers. */
 char *
 cipher_alg_list(char sep, int auth_only)
 {
 	char *tmp, *ret = NULL;
 	size_t nlen, rlen = 0;
 	const struct sshcipher *c;

 	for (c = ciphers; c->name != NULL; c++) {
 		if ((c->flags & CFLAG_INTERNAL) != 0)
 			continue;
 		if (auth_only && c->auth_len == 0)
 			continue;
 		if (ret != NULL)
 			ret[rlen++] = sep;
 		nlen = strlen(c->name);
 		if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
 			free(ret);
 			return NULL;
 		}
 		ret = tmp;
 		memcpy(ret + rlen, c->name, nlen + 1);
 		rlen += nlen;
 	}
 	return ret;
 }

 u_int
 cipher_blocksize(const struct sshcipher *c)
 {
 	return (c->block_size);
 }

 u_int
 cipher_keylen(const struct sshcipher *c)
 {
 	return (c->key_len);
 }

 u_int
 cipher_seclen(const struct sshcipher *c)
 {
 	if (strcmp("3des-cbc", c->name) == 0)
 		return 14;
 	return cipher_keylen(c);
 }

 u_int
 cipher_authlen(const struct sshcipher *c)
 {
 	return (c->auth_len);
 }

 u_int
 cipher_ivlen(const struct sshcipher *c)
 {
 	/*
 	 * Default is cipher block size, except for chacha20+poly1305 that
 	 * needs no IV. XXX make iv_len == -1 default?
 	 */
 	return (c->iv_len != 0 || (c->flags & CFLAG_CHACHAPOLY) != 0) ?
 	    c->iv_len : c->block_size;
 }

 u_int
 cipher_is_cbc(const struct sshcipher *c)
 {
 	return (c->flags & CFLAG_CBC) != 0;
 }

 u_int
 cipher_ctx_is_plaintext(struct sshcipher_ctx *cc)
 {
 	return cc->plaintext;
 }

 const struct sshcipher *
 cipher_by_name(const char *name)
 {
 	const struct sshcipher *c;
 	for (c = ciphers; c->name != NULL; c++)
 		if (strcmp(c->name, name) == 0)
 			return c;
 	return NULL;
 }

 #define	CIPHER_SEP	","
 int
 ciphers_valid(const char *names)
 {
 	const struct sshcipher *c;
 	char *cipher_list, *cp;
 	char *p;

 	if (names == NULL || strcmp(names, "") == 0)
 		return 0;
 	if ((cipher_list = cp = strdup(names)) == NULL)
 		return 0;
 	for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
 	    (p = strsep(&cp, CIPHER_SEP))) {
 		c = cipher_by_name(p);
 		if (c == NULL || (c->flags & CFLAG_INTERNAL) != 0) {
 			free(cipher_list);
 			return 0;
 		}
 	}
 	free(cipher_list);
 	return 1;
 }

 const char *
 cipher_warning_message(const struct sshcipher_ctx *cc)
 {
 	if (cc == NULL || cc->cipher == NULL)
 		return NULL;
 	/* XXX repurpose for CBC warning */
 	return NULL;
 }

 int
 cipher_init(struct sshcipher_ctx **ccp, const struct sshcipher *cipher,
     const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
     int do_encrypt)
 {
 	struct sshcipher_ctx *cc = NULL;
 	int ret = SSH_ERR_INTERNAL_ERROR;
 #ifdef WITH_OPENSSL
 	const EVP_CIPHER *type;
 	int klen;
 #endif

 	*ccp = NULL;
 	if ((cc = calloc(sizeof(*cc), 1)) == NULL)
 		return SSH_ERR_ALLOC_FAIL;

 	cc->plaintext = (cipher->flags & CFLAG_NONE) != 0;
 	cc->encrypt = do_encrypt;

 	if (keylen < cipher->key_len ||
 	    (iv != NULL && ivlen < cipher_ivlen(cipher))) {
 		ret = SSH_ERR_INVALID_ARGUMENT;
 		goto out;
 	}

 	cc->cipher = cipher;
 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
 		ret = chachapoly_init(&cc->cp_ctx, key, keylen);
 		goto out;
 	}
 	if ((cc->cipher->flags & CFLAG_NONE) != 0) {
 		ret = 0;
 		goto out;
 	}
 #ifndef WITH_OPENSSL
 	if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
 		aesctr_keysetup(&cc->ac_ctx, key, 8 * keylen, 8 * ivlen);
 		aesctr_ivsetup(&cc->ac_ctx, iv);
 		ret = 0;
 		goto out;
 	}
 	ret = SSH_ERR_INVALID_ARGUMENT;
 	goto out;
 #else /* WITH_OPENSSL */
 	type = (*cipher->evptype)();
 	if ((cc->evp = EVP_CIPHER_CTX_new()) == NULL) {
 		ret = SSH_ERR_ALLOC_FAIL;
 		goto out;
 	}
 	if (EVP_CipherInit(cc->evp, type, NULL, (u_char *)iv,
 	    (do_encrypt == CIPHER_ENCRYPT)) == 0) {
 		ret = SSH_ERR_LIBCRYPTO_ERROR;
 		goto out;
 	}
 	if (cipher_authlen(cipher) &&
 	    !EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_SET_IV_FIXED,
 	    -1, (u_char *)iv)) {
 		ret = SSH_ERR_LIBCRYPTO_ERROR;
 		goto out;
 	}
 	klen = EVP_CIPHER_CTX_key_length(cc->evp);
 	if (klen > 0 && keylen != (u_int)klen) {
 		if (EVP_CIPHER_CTX_set_key_length(cc->evp, keylen) == 0) {
 			ret = SSH_ERR_LIBCRYPTO_ERROR;
 			goto out;
 		}
 	}
 	if (EVP_CipherInit(cc->evp, NULL, (u_char *)key, NULL, -1) == 0) {
 		ret = SSH_ERR_LIBCRYPTO_ERROR;
 		goto out;
 	}
 	ret = 0;
 #endif /* WITH_OPENSSL */
  out:
 	if (ret == 0) {
 		/* success */
 		*ccp = cc;
 	} else {
 		if (cc != NULL) {
 #ifdef WITH_OPENSSL
 			EVP_CIPHER_CTX_free(cc->evp);
 #endif /* WITH_OPENSSL */
 			explicit_bzero(cc, sizeof(*cc));
 			free(cc);
 		}
 	}
 	return ret;
 }

 /*
  * cipher_crypt() operates as following:
  * Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'.
  * Theses bytes are treated as additional authenticated data for
  * authenticated encryption modes.
  * En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'.
  * Use 'authlen' bytes at offset 'len'+'aadlen' as the authentication tag.
  * This tag is written on encryption and verified on decryption.
  * Both 'aadlen' and 'authlen' can be set to 0.
  */
 int
 cipher_crypt(struct sshcipher_ctx *cc, u_int seqnr, u_char *dest,
    const u_char *src, u_int len, u_int aadlen, u_int authlen)
 {
 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
 		return chachapoly_crypt(&cc->cp_ctx, seqnr, dest, src,
 		    len, aadlen, authlen, cc->encrypt);
 	}
 	if ((cc->cipher->flags & CFLAG_NONE) != 0) {
 		memcpy(dest, src, aadlen + len);
 		return 0;
 	}
 #ifndef WITH_OPENSSL
 	if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
 		if (aadlen)
 			memcpy(dest, src, aadlen);
 		aesctr_encrypt_bytes(&cc->ac_ctx, src + aadlen,
 		    dest + aadlen, len);
 		return 0;
 	}
 	return SSH_ERR_INVALID_ARGUMENT;
 #else
 	if (authlen) {
 		u_char lastiv[1];

 		if (authlen != cipher_authlen(cc->cipher))
 			return SSH_ERR_INVALID_ARGUMENT;
 		/* increment IV */
 		if (!EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_IV_GEN,
 		    1, lastiv))
 			return SSH_ERR_LIBCRYPTO_ERROR;
 		/* set tag on decyption */
 		if (!cc->encrypt &&
 		    !EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_SET_TAG,
 		    authlen, (u_char *)src + aadlen + len))
 			return SSH_ERR_LIBCRYPTO_ERROR;
 	}
 	if (aadlen) {
 		if (authlen &&
 		    EVP_Cipher(cc->evp, NULL, (u_char *)src, aadlen) < 0)
 			return SSH_ERR_LIBCRYPTO_ERROR;
 		memcpy(dest, src, aadlen);
 	}
 	if (len % cc->cipher->block_size)
 		return SSH_ERR_INVALID_ARGUMENT;
 	if (EVP_Cipher(cc->evp, dest + aadlen, (u_char *)src + aadlen,
 	    len) < 0)
 		return SSH_ERR_LIBCRYPTO_ERROR;
 	if (authlen) {
 		/* compute tag (on encrypt) or verify tag (on decrypt) */
 		if (EVP_Cipher(cc->evp, NULL, NULL, 0) < 0)
 			return cc->encrypt ?
 			    SSH_ERR_LIBCRYPTO_ERROR : SSH_ERR_MAC_INVALID;
 		if (cc->encrypt &&
 		    !EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_GET_TAG,
 		    authlen, dest + aadlen + len))
 			return SSH_ERR_LIBCRYPTO_ERROR;
 	}
 	return 0;
 #endif
 }

 /* Extract the packet length, including any decryption necessary beforehand */
 int
 cipher_get_length(struct sshcipher_ctx *cc, u_int *plenp, u_int seqnr,
     const u_char *cp, u_int len)
 {
 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
 		return chachapoly_get_length(&cc->cp_ctx, plenp, seqnr,
 		    cp, len);
 	if (len < 4)
 		return SSH_ERR_MESSAGE_INCOMPLETE;
 	*plenp = PEEK_U32(cp);
 	return 0;
 }

 void
 cipher_free(struct sshcipher_ctx *cc)
 {
 	if (cc == NULL)
 		return;
 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
 		explicit_bzero(&cc->cp_ctx, sizeof(cc->cp_ctx));
 	else if ((cc->cipher->flags & CFLAG_AESCTR) != 0)
 		explicit_bzero(&cc->ac_ctx, sizeof(cc->ac_ctx));
 #ifdef WITH_OPENSSL
 	EVP_CIPHER_CTX_free(cc->evp);
 	cc->evp = NULL;
 #endif
 	explicit_bzero(cc, sizeof(*cc));
 	free(cc);
 }

 /*
  * Exports an IV from the sshcipher_ctx required to export the key
  * state back from the unprivileged child to the privileged parent
  * process.
  */
 int
 cipher_get_keyiv_len(const struct sshcipher_ctx *cc)
 {
 	const struct sshcipher *c = cc->cipher;

 	if ((c->flags & CFLAG_CHACHAPOLY) != 0)
 		return 0;
 	else if ((c->flags & CFLAG_AESCTR) != 0)
 		return sizeof(cc->ac_ctx.ctr);
 #ifdef WITH_OPENSSL
 	return EVP_CIPHER_CTX_iv_length(cc->evp);
 #else
 	return 0;
 #endif
 }

 int
 cipher_get_keyiv(struct sshcipher_ctx *cc, u_char *iv, u_int len)
 {
 #ifdef WITH_OPENSSL
 	const struct sshcipher *c = cc->cipher;
 	int evplen;
 #endif

 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
 		if (len != 0)
 			return SSH_ERR_INVALID_ARGUMENT;
 		return 0;
 	}
 	if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
 		if (len != sizeof(cc->ac_ctx.ctr))
 			return SSH_ERR_INVALID_ARGUMENT;
 		memcpy(iv, cc->ac_ctx.ctr, len);
 		return 0;
 	}
 	if ((cc->cipher->flags & CFLAG_NONE) != 0)
 		return 0;

 #ifdef WITH_OPENSSL
 	evplen = EVP_CIPHER_CTX_iv_length(cc->evp);
 	if (evplen == 0)
 		return 0;
 	else if (evplen < 0)
 		return SSH_ERR_LIBCRYPTO_ERROR;
 	if ((u_int)evplen != len)
 		return SSH_ERR_INVALID_ARGUMENT;
 #ifndef OPENSSL_HAVE_EVPCTR
 	if (c->evptype == evp_aes_128_ctr)
 		ssh_aes_ctr_iv(cc->evp, 0, iv, len);
 	else
 #endif
 	if (cipher_authlen(c)) {
 		if (!EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_IV_GEN,
 		   len, iv))
 		       return SSH_ERR_LIBCRYPTO_ERROR;
 	} else
 		memcpy(iv, cc->evp->iv, len);
 #endif
 	return 0;
 }

 int
 cipher_set_keyiv(struct sshcipher_ctx *cc, const u_char *iv)
 {
 #ifdef WITH_OPENSSL
 	const struct sshcipher *c = cc->cipher;
 	int evplen = 0;
 #endif

 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
 		return 0;
 	if ((cc->cipher->flags & CFLAG_NONE) != 0)
 		return 0;

 #ifdef WITH_OPENSSL
 	evplen = EVP_CIPHER_CTX_iv_length(cc->evp);
 	if (evplen <= 0)
 		return SSH_ERR_LIBCRYPTO_ERROR;
 #ifndef OPENSSL_HAVE_EVPCTR
 	/* XXX iv arg is const, but ssh_aes_ctr_iv isn't */
 	if (c->evptype == evp_aes_128_ctr)
 		ssh_aes_ctr_iv(cc->evp, 1, (u_char *)iv, evplen);
 	else
 #endif
 	if (cipher_authlen(c)) {
 		/* XXX iv arg is const, but EVP_CIPHER_CTX_ctrl isn't */
 		if (!EVP_CIPHER_CTX_ctrl(cc->evp,
 		    EVP_CTRL_GCM_SET_IV_FIXED, -1, (void *)iv))
 			return SSH_ERR_LIBCRYPTO_ERROR;
 	} else
 		memcpy(cc->evp->iv, iv, evplen);
 #endif
 	return 0;
 }

 #ifdef WITH_OPENSSL
 #define EVP_X_STATE(evp)	(evp)->cipher_data
 #define EVP_X_STATE_LEN(evp)	(evp)->cipher->ctx_size
 #endif

 int
 cipher_get_keycontext(const struct sshcipher_ctx *cc, u_char *dat)
 {
 #if defined(WITH_OPENSSL) && !defined(OPENSSL_NO_RC4)
 	const struct sshcipher *c = cc->cipher;
 	int plen = 0;

 	if (c->evptype == EVP_rc4) {
 		plen = EVP_X_STATE_LEN(cc->evp);
 		if (dat == NULL)
 			return (plen);
 		memcpy(dat, EVP_X_STATE(cc->evp), plen);
 	}
 	return (plen);
 #else
 	return 0;
 #endif
 }

 void
 cipher_set_keycontext(struct sshcipher_ctx *cc, const u_char *dat)
 {
 #if defined(WITH_OPENSSL) && !defined(OPENSSL_NO_RC4)
 	const struct sshcipher *c = cc->cipher;
 	int plen;

 	if (c->evptype == EVP_rc4) {
 		plen = EVP_X_STATE_LEN(cc->evp);
 		memcpy(EVP_X_STATE(cc->evp), dat, plen);
 	}
 #endif
 }
	/* $OpenBSD: cipher.c,v 1.111 2018/02/23 15:58:37 markus Exp $ */
	/*
	* Author: Tatu Ylonen <ylo@cs.hut.fi>
	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	* All rights reserved
	*
	* As far as I am concerned, the code I have written for this software
	* can be used freely for any purpose. Any derived versions of this
	* software must be clearly marked as such, and if the derived work is
	* incompatible with the protocol description in the RFC file, it must be
	* called by a name other than "ssh" or "Secure Shell".
	*
	*
	* Copyright (c) 1999 Niels Provos. All rights reserved.
	* Copyright (c) 1999, 2000 Markus Friedl. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "includes.h"

	#include <sys/types.h>

	#include <string.h>
	#include <stdarg.h>
	#include <stdio.h>

	#include "cipher.h"
	#include "misc.h"
	#include "sshbuf.h"
	#include "ssherr.h"
	#include "digest.h"

	#include "openbsd-compat/openssl-compat.h"


	struct sshcipher_ctx {
	int plaintext;
	int encrypt;
	EVP_CIPHER_CTX *evp;
	struct chachapoly_ctx cp_ctx; /* XXX union with evp? */
	struct aesctr_ctx ac_ctx; /* XXX union with evp? */
	const struct sshcipher *cipher;
	};

	struct sshcipher {
	char *name;
	u_int block_size;
	u_int key_len;
	u_int iv_len; /* defaults to block_size */
	u_int auth_len;
	u_int flags;
	#define CFLAG_CBC (1<<0)
	#define CFLAG_CHACHAPOLY (1<<1)
	#define CFLAG_AESCTR (1<<2)
	#define CFLAG_NONE (1<<3)
	#define CFLAG_INTERNAL CFLAG_NONE /* Don't use "none" for packets */
	#ifdef WITH_OPENSSL
	const EVP_CIPHER (evptype)(void);
	#else
	void *ignored;
	#endif
	};

	static const struct sshcipher ciphers[] = {
	#ifdef WITH_OPENSSL
	#ifndef OPENSSL_NO_DES
	{ "3des-cbc", 8, 24, 0, 0, CFLAG_CBC, EVP_des_ede3_cbc },
	#endif
	{ "aes128-cbc", 16, 16, 0, 0, CFLAG_CBC, EVP_aes_128_cbc },
	{ "aes192-cbc", 16, 24, 0, 0, CFLAG_CBC, EVP_aes_192_cbc },
	{ "aes256-cbc", 16, 32, 0, 0, CFLAG_CBC, EVP_aes_256_cbc },
	{ "rijndael-cbc@lysator.liu.se",
	16, 32, 0, 0, CFLAG_CBC, EVP_aes_256_cbc },
	{ "aes128-ctr", 16, 16, 0, 0, 0, EVP_aes_128_ctr },
	{ "aes192-ctr", 16, 24, 0, 0, 0, EVP_aes_192_ctr },
	{ "aes256-ctr", 16, 32, 0, 0, 0, EVP_aes_256_ctr },
	# ifdef OPENSSL_HAVE_EVPGCM
	{ "aes128-gcm@openssh.com",
	16, 16, 12, 16, 0, EVP_aes_128_gcm },
	{ "aes256-gcm@openssh.com",
	16, 32, 12, 16, 0, EVP_aes_256_gcm },
	# endif /* OPENSSL_HAVE_EVPGCM */
	#else
	{ "aes128-ctr", 16, 16, 0, 0, CFLAG_AESCTR, NULL },
	{ "aes192-ctr", 16, 24, 0, 0, CFLAG_AESCTR, NULL },
	{ "aes256-ctr", 16, 32, 0, 0, CFLAG_AESCTR, NULL },
	#endif
	{ "chacha20-poly1305@openssh.com",
	8, 64, 0, 16, CFLAG_CHACHAPOLY, NULL },
	{ "none", 8, 0, 0, 0, CFLAG_NONE, NULL },

	{ NULL, 0, 0, 0, 0, 0, NULL }
	};

	/--/

	/* Returns a comma-separated list of supported ciphers. */
	char *
	cipher_alg_list(char sep, int auth_only)
	{
	char tmp, ret = NULL;
	size_t nlen, rlen = 0;
	const struct sshcipher *c;

	for (c = ciphers; c->name != NULL; c++) {
	if ((c->flags & CFLAG_INTERNAL) != 0)
	continue;
	if (auth_only && c->auth_len == 0)
	continue;
	if (ret != NULL)
	ret[rlen++] = sep;
	nlen = strlen(c->name);
	if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
	free(ret);
	return NULL;
	}
	ret = tmp;
	memcpy(ret + rlen, c->name, nlen + 1);
	rlen += nlen;
	}
	return ret;
	}

	u_int
	cipher_blocksize(const struct sshcipher *c)
	{
	return (c->block_size);
	}

	u_int
	cipher_keylen(const struct sshcipher *c)
	{
	return (c->key_len);
	}

	u_int
	cipher_seclen(const struct sshcipher *c)
	{
	if (strcmp("3des-cbc", c->name) == 0)
	return 14;
	return cipher_keylen(c);
	}

	u_int
	cipher_authlen(const struct sshcipher *c)
	{
	return (c->auth_len);
	}

	u_int
	cipher_ivlen(const struct sshcipher *c)
	{
	/*
	* Default is cipher block size, except for chacha20+poly1305 that
	* needs no IV. XXX make iv_len == -1 default?
	*/
	return (c->iv_len != 0 \|\| (c->flags & CFLAG_CHACHAPOLY) != 0) ?
	c->iv_len : c->block_size;
	}

	u_int
	cipher_is_cbc(const struct sshcipher *c)
	{
	return (c->flags & CFLAG_CBC) != 0;
	}

	u_int
	cipher_ctx_is_plaintext(struct sshcipher_ctx *cc)
	{
	return cc->plaintext;
	}

	const struct sshcipher *
	cipher_by_name(const char *name)
	{
	const struct sshcipher *c;
	for (c = ciphers; c->name != NULL; c++)
	if (strcmp(c->name, name) == 0)
	return c;
	return NULL;
	}

	#define CIPHER_SEP ","
	int
	ciphers_valid(const char *names)
	{
	const struct sshcipher *c;
	char cipher_list, cp;
	char *p;

	if (names == NULL \|\| strcmp(names, "") == 0)
	return 0;
	if ((cipher_list = cp = strdup(names)) == NULL)
	return 0;
	for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
	(p = strsep(&cp, CIPHER_SEP))) {
	c = cipher_by_name(p);
	if (c == NULL \|\| (c->flags & CFLAG_INTERNAL) != 0) {
	free(cipher_list);
	return 0;
	}
	}
	free(cipher_list);
	return 1;
	}

	const char *
	cipher_warning_message(const struct sshcipher_ctx *cc)
	{
	if (cc == NULL \|\| cc->cipher == NULL)
	return NULL;
	/* XXX repurpose for CBC warning */
	return NULL;
	}

	int
	cipher_init(struct sshcipher_ctx *ccp, const struct sshcipher cipher,
	const u_char key, u_int keylen, const u_char iv, u_int ivlen,
	int do_encrypt)
	{
	struct sshcipher_ctx *cc = NULL;
	int ret = SSH_ERR_INTERNAL_ERROR;
	#ifdef WITH_OPENSSL
	const EVP_CIPHER *type;
	int klen;
	#endif

	*ccp = NULL;
	if ((cc = calloc(sizeof(*cc), 1)) == NULL)
	return SSH_ERR_ALLOC_FAIL;

	cc->plaintext = (cipher->flags & CFLAG_NONE) != 0;
	cc->encrypt = do_encrypt;

	if (keylen < cipher->key_len \|\|
	(iv != NULL && ivlen < cipher_ivlen(cipher))) {
	ret = SSH_ERR_INVALID_ARGUMENT;
	goto out;
	}

	cc->cipher = cipher;
	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
	ret = chachapoly_init(&cc->cp_ctx, key, keylen);
	goto out;
	}
	if ((cc->cipher->flags & CFLAG_NONE) != 0) {
	ret = 0;
	goto out;
	}
	#ifndef WITH_OPENSSL
	if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
	aesctr_keysetup(&cc->ac_ctx, key, 8 * keylen, 8 * ivlen);
	aesctr_ivsetup(&cc->ac_ctx, iv);
	ret = 0;
	goto out;
	}
	ret = SSH_ERR_INVALID_ARGUMENT;
	goto out;
	#else /* WITH_OPENSSL */
	type = (*cipher->evptype)();
	if ((cc->evp = EVP_CIPHER_CTX_new()) == NULL) {
	ret = SSH_ERR_ALLOC_FAIL;
	goto out;
	}
	if (EVP_CipherInit(cc->evp, type, NULL, (u_char *)iv,
	(do_encrypt == CIPHER_ENCRYPT)) == 0) {
	ret = SSH_ERR_LIBCRYPTO_ERROR;
	goto out;
	}
	if (cipher_authlen(cipher) &&
	!EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_SET_IV_FIXED,
	-1, (u_char *)iv)) {
	ret = SSH_ERR_LIBCRYPTO_ERROR;
	goto out;
	}
	klen = EVP_CIPHER_CTX_key_length(cc->evp);
	if (klen > 0 && keylen != (u_int)klen) {
	if (EVP_CIPHER_CTX_set_key_length(cc->evp, keylen) == 0) {
	ret = SSH_ERR_LIBCRYPTO_ERROR;
	goto out;
	}
	}
	if (EVP_CipherInit(cc->evp, NULL, (u_char *)key, NULL, -1) == 0) {
	ret = SSH_ERR_LIBCRYPTO_ERROR;
	goto out;
	}
	ret = 0;
	#endif /* WITH_OPENSSL */
	out:
	if (ret == 0) {
	/* success */
	*ccp = cc;
	} else {
	if (cc != NULL) {
	#ifdef WITH_OPENSSL
	EVP_CIPHER_CTX_free(cc->evp);
	#endif /* WITH_OPENSSL */
	explicit_bzero(cc, sizeof(*cc));
	free(cc);
	}
	}
	return ret;
	}

	/*
	* cipher_crypt() operates as following:
	* Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'.
	* Theses bytes are treated as additional authenticated data for
	* authenticated encryption modes.
	* En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'.
	* Use 'authlen' bytes at offset 'len'+'aadlen' as the authentication tag.
	* This tag is written on encryption and verified on decryption.
	* Both 'aadlen' and 'authlen' can be set to 0.
	*/
	int
	cipher_crypt(struct sshcipher_ctx cc, u_int seqnr, u_char dest,
	const u_char *src, u_int len, u_int aadlen, u_int authlen)
	{
	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
	return chachapoly_crypt(&cc->cp_ctx, seqnr, dest, src,
	len, aadlen, authlen, cc->encrypt);
	}
	if ((cc->cipher->flags & CFLAG_NONE) != 0) {
	memcpy(dest, src, aadlen + len);
	return 0;
	}
	#ifndef WITH_OPENSSL
	if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
	if (aadlen)
	memcpy(dest, src, aadlen);
	aesctr_encrypt_bytes(&cc->ac_ctx, src + aadlen,
	dest + aadlen, len);
	return 0;
	}
	return SSH_ERR_INVALID_ARGUMENT;
	#else
	if (authlen) {
	u_char lastiv[1];

	if (authlen != cipher_authlen(cc->cipher))
	return SSH_ERR_INVALID_ARGUMENT;
	/* increment IV */
	if (!EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_IV_GEN,
	1, lastiv))
	return SSH_ERR_LIBCRYPTO_ERROR;
	/* set tag on decyption */
	if (!cc->encrypt &&
	!EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_SET_TAG,
	authlen, (u_char *)src + aadlen + len))
	return SSH_ERR_LIBCRYPTO_ERROR;
	}
	if (aadlen) {
	if (authlen &&
	EVP_Cipher(cc->evp, NULL, (u_char *)src, aadlen) < 0)
	return SSH_ERR_LIBCRYPTO_ERROR;
	memcpy(dest, src, aadlen);
	}
	if (len % cc->cipher->block_size)
	return SSH_ERR_INVALID_ARGUMENT;
	if (EVP_Cipher(cc->evp, dest + aadlen, (u_char *)src + aadlen,
	len) < 0)
	return SSH_ERR_LIBCRYPTO_ERROR;
	if (authlen) {
	/* compute tag (on encrypt) or verify tag (on decrypt) */
	if (EVP_Cipher(cc->evp, NULL, NULL, 0) < 0)
	return cc->encrypt ?
	SSH_ERR_LIBCRYPTO_ERROR : SSH_ERR_MAC_INVALID;
	if (cc->encrypt &&
	!EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_GET_TAG,
	authlen, dest + aadlen + len))
	return SSH_ERR_LIBCRYPTO_ERROR;
	}
	return 0;
	#endif
	}

	/* Extract the packet length, including any decryption necessary beforehand */
	int
	cipher_get_length(struct sshcipher_ctx cc, u_int plenp, u_int seqnr,
	const u_char *cp, u_int len)
	{
	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
	return chachapoly_get_length(&cc->cp_ctx, plenp, seqnr,
	cp, len);
	if (len < 4)
	return SSH_ERR_MESSAGE_INCOMPLETE;
	*plenp = PEEK_U32(cp);
	return 0;
	}

	void
	cipher_free(struct sshcipher_ctx *cc)
	{
	if (cc == NULL)
	return;
	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
	explicit_bzero(&cc->cp_ctx, sizeof(cc->cp_ctx));
	else if ((cc->cipher->flags & CFLAG_AESCTR) != 0)
	explicit_bzero(&cc->ac_ctx, sizeof(cc->ac_ctx));
	#ifdef WITH_OPENSSL
	EVP_CIPHER_CTX_free(cc->evp);
	cc->evp = NULL;
	#endif
	explicit_bzero(cc, sizeof(*cc));
	free(cc);
	}

	/*
	* Exports an IV from the sshcipher_ctx required to export the key
	* state back from the unprivileged child to the privileged parent
	* process.
	*/
	int
	cipher_get_keyiv_len(const struct sshcipher_ctx *cc)
	{
	const struct sshcipher *c = cc->cipher;

	if ((c->flags & CFLAG_CHACHAPOLY) != 0)
	return 0;
	else if ((c->flags & CFLAG_AESCTR) != 0)
	return sizeof(cc->ac_ctx.ctr);
	#ifdef WITH_OPENSSL
	return EVP_CIPHER_CTX_iv_length(cc->evp);
	#else
	return 0;
	#endif
	}

	int
	cipher_get_keyiv(struct sshcipher_ctx cc, u_char iv, u_int len)
	{
	#ifdef WITH_OPENSSL
	const struct sshcipher *c = cc->cipher;
	int evplen;
	#endif

	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
	if (len != 0)
	return SSH_ERR_INVALID_ARGUMENT;
	return 0;
	}
	if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
	if (len != sizeof(cc->ac_ctx.ctr))
	return SSH_ERR_INVALID_ARGUMENT;
	memcpy(iv, cc->ac_ctx.ctr, len);
	return 0;
	}
	if ((cc->cipher->flags & CFLAG_NONE) != 0)
	return 0;

	#ifdef WITH_OPENSSL
	evplen = EVP_CIPHER_CTX_iv_length(cc->evp);
	if (evplen == 0)
	return 0;
	else if (evplen < 0)
	return SSH_ERR_LIBCRYPTO_ERROR;
	if ((u_int)evplen != len)
	return SSH_ERR_INVALID_ARGUMENT;
	#ifndef OPENSSL_HAVE_EVPCTR
	if (c->evptype == evp_aes_128_ctr)
	ssh_aes_ctr_iv(cc->evp, 0, iv, len);
	else
	#endif
	if (cipher_authlen(c)) {
	if (!EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_IV_GEN,
	len, iv))
	return SSH_ERR_LIBCRYPTO_ERROR;
	} else
	memcpy(iv, cc->evp->iv, len);
	#endif
	return 0;
	}

	int
	cipher_set_keyiv(struct sshcipher_ctx cc, const u_char iv)
	{
	#ifdef WITH_OPENSSL
	const struct sshcipher *c = cc->cipher;
	int evplen = 0;
	#endif

	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
	return 0;
	if ((cc->cipher->flags & CFLAG_NONE) != 0)
	return 0;

	#ifdef WITH_OPENSSL
	evplen = EVP_CIPHER_CTX_iv_length(cc->evp);
	if (evplen <= 0)
	return SSH_ERR_LIBCRYPTO_ERROR;
	#ifndef OPENSSL_HAVE_EVPCTR
	/* XXX iv arg is const, but ssh_aes_ctr_iv isn't */
	if (c->evptype == evp_aes_128_ctr)
	ssh_aes_ctr_iv(cc->evp, 1, (u_char *)iv, evplen);
	else
	#endif
	if (cipher_authlen(c)) {
	/* XXX iv arg is const, but EVP_CIPHER_CTX_ctrl isn't */
	if (!EVP_CIPHER_CTX_ctrl(cc->evp,
	EVP_CTRL_GCM_SET_IV_FIXED, -1, (void *)iv))
	return SSH_ERR_LIBCRYPTO_ERROR;
	} else
	memcpy(cc->evp->iv, iv, evplen);
	#endif
	return 0;
	}

	#ifdef WITH_OPENSSL
	#define EVP_X_STATE(evp) (evp)->cipher_data
	#define EVP_X_STATE_LEN(evp) (evp)->cipher->ctx_size
	#endif

	int
	cipher_get_keycontext(const struct sshcipher_ctx cc, u_char dat)
	{
	#if defined(WITH_OPENSSL) && !defined(OPENSSL_NO_RC4)
	const struct sshcipher *c = cc->cipher;
	int plen = 0;

	if (c->evptype == EVP_rc4) {
	plen = EVP_X_STATE_LEN(cc->evp);
	if (dat == NULL)
	return (plen);
	memcpy(dat, EVP_X_STATE(cc->evp), plen);
	}
	return (plen);
	#else
	return 0;
	#endif
	}

	void
	cipher_set_keycontext(struct sshcipher_ctx cc, const u_char dat)
	{
	#if defined(WITH_OPENSSL) && !defined(OPENSSL_NO_RC4)
	const struct sshcipher *c = cc->cipher;
	int plen;

	if (c->evptype == EVP_rc4) {
	plen = EVP_X_STATE_LEN(cc->evp);
	memcpy(EVP_X_STATE(cc->evp), dat, plen);
	}
	#endif
	}