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Remove the pre-standardization cipher rijndael-cbc@lysator.liu.se.
It is an alias for aes256-cbc which was standardized in RFC4253 (2006),
has been deprecated and disabled by default since OpenSSH 7.2 (2016)
and was only briefly documented in ssh.1 in 2001.

This will reduce the amount of work the cipher/kex regression tests need
to do by a little bit.  ok markus@ djm@

/* $OpenBSD: cipher.c,v 1.118 2020/12/21 11:09:32 dtucker 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 <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"

#ifndef WITH_OPENSSL
#define EVP_CIPHER_CTX void
#endif

struct sshcipher_ctx {
	int	plaintext;
	int	encrypt;
	EVP_CIPHER_CTX *evp;
	struct chachapoly_ctx *cp_ctx;
	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
	{ "3des-cbc",		8, 24, 0, 0, CFLAG_CBC, EVP_des_ede3_cbc },
	{ "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 },
	{ "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 },
	{ "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 },
#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;
}

const char *
compression_alg_list(int compression)
{
#ifdef WITH_ZLIB
	return compression ? "zlib@openssh.com,zlib,none" :
	    "none,zlib@openssh.com,zlib";
#else
	return "none";
#endif
}

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) {
		cc->cp_ctx = chachapoly_new(key, keylen);
		ret = cc->cp_ctx != NULL ? 0 : SSH_ERR_INVALID_ARGUMENT;
		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 */
			freezero(cc, sizeof(*cc));
		}
	}
	return ret;
}

/*
 * cipher_crypt() operates as following:
 * Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'.
 * These 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) {
		chachapoly_free(cc->cp_ctx);
		cc->cp_ctx = NULL;
	} 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
	freezero(cc, sizeof(*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, size_t 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 ((size_t)evplen != len)
		return SSH_ERR_INVALID_ARGUMENT;
	if (cipher_authlen(c)) {
		if (!EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_IV_GEN,
		   len, iv))
		       return SSH_ERR_LIBCRYPTO_ERROR;
	} else if (!EVP_CIPHER_CTX_get_iv(cc->evp, iv, len))
	       return SSH_ERR_LIBCRYPTO_ERROR;
#endif
	return 0;
}

int
cipher_set_keyiv(struct sshcipher_ctx *cc, const u_char *iv, size_t len)
{
#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;
	if ((size_t)evplen != len)
		return SSH_ERR_INVALID_ARGUMENT;
	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 if (!EVP_CIPHER_CTX_set_iv(cc->evp, iv, evplen))
		return SSH_ERR_LIBCRYPTO_ERROR;
#endif
	return 0;
}