authfile.c - security/openssh-library - Rivoreo Source Code Repositories

 /* $OpenBSD: authfile.c,v 1.71 2006/07/22 20:48:22 stevesk Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
  * This file contains functions for reading and writing identity files, and
  * for reading the passphrase from the user.
  *
  * 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) 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 <sys/stat.h>

 #include <openssl/err.h>
 #include <openssl/evp.h>
 #include <openssl/pem.h>

 #include <errno.h>
 #include <fcntl.h>
 #include <string.h>
 #include <unistd.h>

 #include "cipher.h"
 #include "xmalloc.h"
 #include "buffer.h"
 #include "bufaux.h"
 #include "key.h"
 #include "ssh.h"
 #include "log.h"
 #include "authfile.h"
 #include "rsa.h"
 #include "misc.h"
 #include "atomicio.h"

 /* Version identification string for SSH v1 identity files. */
 static const char authfile_id_string[] =
     "SSH PRIVATE KEY FILE FORMAT 1.1\n";

 /*
  * Saves the authentication (private) key in a file, encrypting it with
  * passphrase.  The identification of the file (lowest 64 bits of n) will
  * precede the key to provide identification of the key without needing a
  * passphrase.
  */

 static int
 key_save_private_rsa1(Key *key, const char *filename, const char *passphrase,
     const char *comment)
 {
 	Buffer buffer, encrypted;
 	u_char buf[100], *cp;
 	int fd, i, cipher_num;
 	CipherContext ciphercontext;
 	Cipher *cipher;
 	u_int32_t rnd;

 	/*
 	 * If the passphrase is empty, use SSH_CIPHER_NONE to ease converting
 	 * to another cipher; otherwise use SSH_AUTHFILE_CIPHER.
 	 */
 	cipher_num = (strcmp(passphrase, "") == 0) ?
 	    SSH_CIPHER_NONE : SSH_AUTHFILE_CIPHER;
 	if ((cipher = cipher_by_number(cipher_num)) == NULL)
 		fatal("save_private_key_rsa: bad cipher");

 	/* This buffer is used to built the secret part of the private key. */
 	buffer_init(&buffer);

 	/* Put checkbytes for checking passphrase validity. */
 	rnd = arc4random();
 	buf[0] = rnd & 0xff;
 	buf[1] = (rnd >> 8) & 0xff;
 	buf[2] = buf[0];
 	buf[3] = buf[1];
 	buffer_append(&buffer, buf, 4);

 	/*
 	 * Store the private key (n and e will not be stored because they
 	 * will be stored in plain text, and storing them also in encrypted
 	 * format would just give known plaintext).
 	 */
 	buffer_put_bignum(&buffer, key->rsa->d);
 	buffer_put_bignum(&buffer, key->rsa->iqmp);
 	buffer_put_bignum(&buffer, key->rsa->q);	/* reverse from SSL p */
 	buffer_put_bignum(&buffer, key->rsa->p);	/* reverse from SSL q */

 	/* Pad the part to be encrypted until its size is a multiple of 8. */
 	while (buffer_len(&buffer) % 8 != 0)
 		buffer_put_char(&buffer, 0);

 	/* This buffer will be used to contain the data in the file. */
 	buffer_init(&encrypted);

 	/* First store keyfile id string. */
 	for (i = 0; authfile_id_string[i]; i++)
 		buffer_put_char(&encrypted, authfile_id_string[i]);
 	buffer_put_char(&encrypted, 0);

 	/* Store cipher type. */
 	buffer_put_char(&encrypted, cipher_num);
 	buffer_put_int(&encrypted, 0);	/* For future extension */

 	/* Store public key.  This will be in plain text. */
 	buffer_put_int(&encrypted, BN_num_bits(key->rsa->n));
 	buffer_put_bignum(&encrypted, key->rsa->n);
 	buffer_put_bignum(&encrypted, key->rsa->e);
 	buffer_put_cstring(&encrypted, comment);

 	/* Allocate space for the private part of the key in the buffer. */
 	cp = buffer_append_space(&encrypted, buffer_len(&buffer));

 	cipher_set_key_string(&ciphercontext, cipher, passphrase,
 	    CIPHER_ENCRYPT);
 	cipher_crypt(&ciphercontext, cp,
 	    buffer_ptr(&buffer), buffer_len(&buffer));
 	cipher_cleanup(&ciphercontext);
 	memset(&ciphercontext, 0, sizeof(ciphercontext));

 	/* Destroy temporary data. */
 	memset(buf, 0, sizeof(buf));
 	buffer_free(&buffer);

 	fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600);
 	if (fd < 0) {
 		error("open %s failed: %s.", filename, strerror(errno));
 		buffer_free(&encrypted);
 		return 0;
 	}
 	if (atomicio(vwrite, fd, buffer_ptr(&encrypted),
 	    buffer_len(&encrypted)) != buffer_len(&encrypted)) {
 		error("write to key file %s failed: %s", filename,
 		    strerror(errno));
 		buffer_free(&encrypted);
 		close(fd);
 		unlink(filename);
 		return 0;
 	}
 	close(fd);
 	buffer_free(&encrypted);
 	return 1;
 }

 /* save SSH v2 key in OpenSSL PEM format */
 static int
 key_save_private_pem(Key *key, const char *filename, const char *_passphrase,
     const char *comment)
 {
 	FILE *fp;
 	int fd;
 	int success = 0;
 	int len = strlen(_passphrase);
 	u_char *passphrase = (len > 0) ? (u_char *)_passphrase : NULL;
 	const EVP_CIPHER *cipher = (len > 0) ? EVP_des_ede3_cbc() : NULL;

 	if (len > 0 && len <= 4) {
 		error("passphrase too short: have %d bytes, need > 4", len);
 		return 0;
 	}
 	fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600);
 	if (fd < 0) {
 		error("open %s failed: %s.", filename, strerror(errno));
 		return 0;
 	}
 	fp = fdopen(fd, "w");
 	if (fp == NULL ) {
 		error("fdopen %s failed: %s.", filename, strerror(errno));
 		close(fd);
 		return 0;
 	}
 	switch (key->type) {
 	case KEY_DSA:
 		success = PEM_write_DSAPrivateKey(fp, key->dsa,
 		    cipher, passphrase, len, NULL, NULL);
 		break;
 	case KEY_RSA:
 		success = PEM_write_RSAPrivateKey(fp, key->rsa,
 		    cipher, passphrase, len, NULL, NULL);
 		break;
 	}
 	fclose(fp);
 	return success;
 }

 int
 key_save_private(Key *key, const char *filename, const char *passphrase,
     const char *comment)
 {
 	switch (key->type) {
 	case KEY_RSA1:
 		return key_save_private_rsa1(key, filename, passphrase,
 		    comment);
 	case KEY_DSA:
 	case KEY_RSA:
 		return key_save_private_pem(key, filename, passphrase,
 		    comment);
 	default:
 		break;
 	}
 	error("key_save_private: cannot save key type %d", key->type);
 	return 0;
 }

 /*
  * Loads the public part of the ssh v1 key file.  Returns NULL if an error was
  * encountered (the file does not exist or is not readable), and the key
  * otherwise.
  */

 static Key *
 key_load_public_rsa1(int fd, const char *filename, char **commentp)
 {
 	Buffer buffer;
 	Key *pub;
 	struct stat st;
 	char *cp;
 	u_int i;
 	size_t len;

 	if (fstat(fd, &st) < 0) {
 		error("fstat for key file %.200s failed: %.100s",
 		    filename, strerror(errno));
 		return NULL;
 	}
 	if (st.st_size > 1*1024*1024) {
 		error("key file %.200s too large", filename);
 		return NULL;
 	}
 	len = (size_t)st.st_size;		/* truncated */

 	buffer_init(&buffer);
 	cp = buffer_append_space(&buffer, len);

 	if (atomicio(read, fd, cp, len) != len) {
 		debug("Read from key file %.200s failed: %.100s", filename,
 		    strerror(errno));
 		buffer_free(&buffer);
 		return NULL;
 	}

 	/* Check that it is at least big enough to contain the ID string. */
 	if (len < sizeof(authfile_id_string)) {
 		debug3("Not a RSA1 key file %.200s.", filename);
 		buffer_free(&buffer);
 		return NULL;
 	}
 	/*
 	 * Make sure it begins with the id string.  Consume the id string
 	 * from the buffer.
 	 */
 	for (i = 0; i < sizeof(authfile_id_string); i++)
 		if (buffer_get_char(&buffer) != authfile_id_string[i]) {
 			debug3("Not a RSA1 key file %.200s.", filename);
 			buffer_free(&buffer);
 			return NULL;
 		}
 	/* Skip cipher type and reserved data. */
 	(void) buffer_get_char(&buffer);	/* cipher type */
 	(void) buffer_get_int(&buffer);		/* reserved */

 	/* Read the public key from the buffer. */
 	(void) buffer_get_int(&buffer);
 	pub = key_new(KEY_RSA1);
 	buffer_get_bignum(&buffer, pub->rsa->n);
 	buffer_get_bignum(&buffer, pub->rsa->e);
 	if (commentp)
 		*commentp = buffer_get_string(&buffer, NULL);
 	/* The encrypted private part is not parsed by this function. */

 	buffer_free(&buffer);
 	return pub;
 }

 /* load public key from private-key file, works only for SSH v1 */
 Key *
 key_load_public_type(int type, const char *filename, char **commentp)
 {
 	Key *pub;
 	int fd;

 	if (type == KEY_RSA1) {
 		fd = open(filename, O_RDONLY);
 		if (fd < 0)
 			return NULL;
 		pub = key_load_public_rsa1(fd, filename, commentp);
 		close(fd);
 		return pub;
 	}
 	return NULL;
 }

 /*
  * Loads the private key from the file.  Returns 0 if an error is encountered
  * (file does not exist or is not readable, or passphrase is bad). This
  * initializes the private key.
  * Assumes we are called under uid of the owner of the file.
  */

 static Key *
 key_load_private_rsa1(int fd, const char *filename, const char *passphrase,
     char **commentp)
 {
 	u_int i;
 	int check1, check2, cipher_type;
 	size_t len;
 	Buffer buffer, decrypted;
 	u_char *cp;
 	CipherContext ciphercontext;
 	Cipher *cipher;
 	Key *prv = NULL;
 	struct stat st;

 	if (fstat(fd, &st) < 0) {
 		error("fstat for key file %.200s failed: %.100s",
 		    filename, strerror(errno));
 		close(fd);
 		return NULL;
 	}
 	if (st.st_size > 1*1024*1024) {
 		error("key file %.200s too large", filename);
 		close(fd);
 		return (NULL);
 	}
 	len = (size_t)st.st_size;		/* truncated */

 	buffer_init(&buffer);
 	cp = buffer_append_space(&buffer, len);

 	if (atomicio(read, fd, cp, len) != len) {
 		debug("Read from key file %.200s failed: %.100s", filename,
 		    strerror(errno));
 		buffer_free(&buffer);
 		close(fd);
 		return NULL;
 	}

 	/* Check that it is at least big enough to contain the ID string. */
 	if (len < sizeof(authfile_id_string)) {
 		debug3("Not a RSA1 key file %.200s.", filename);
 		buffer_free(&buffer);
 		close(fd);
 		return NULL;
 	}
 	/*
 	 * Make sure it begins with the id string.  Consume the id string
 	 * from the buffer.
 	 */
 	for (i = 0; i < sizeof(authfile_id_string); i++)
 		if (buffer_get_char(&buffer) != authfile_id_string[i]) {
 			debug3("Not a RSA1 key file %.200s.", filename);
 			buffer_free(&buffer);
 			close(fd);
 			return NULL;
 		}

 	/* Read cipher type. */
 	cipher_type = buffer_get_char(&buffer);
 	(void) buffer_get_int(&buffer);	/* Reserved data. */

 	/* Read the public key from the buffer. */
 	(void) buffer_get_int(&buffer);
 	prv = key_new_private(KEY_RSA1);

 	buffer_get_bignum(&buffer, prv->rsa->n);
 	buffer_get_bignum(&buffer, prv->rsa->e);
 	if (commentp)
 		*commentp = buffer_get_string(&buffer, NULL);
 	else
 		xfree(buffer_get_string(&buffer, NULL));

 	/* Check that it is a supported cipher. */
 	cipher = cipher_by_number(cipher_type);
 	if (cipher == NULL) {
 		debug("Unsupported cipher %d used in key file %.200s.",
 		    cipher_type, filename);
 		buffer_free(&buffer);
 		goto fail;
 	}
 	/* Initialize space for decrypted data. */
 	buffer_init(&decrypted);
 	cp = buffer_append_space(&decrypted, buffer_len(&buffer));

 	/* Rest of the buffer is encrypted.  Decrypt it using the passphrase. */
 	cipher_set_key_string(&ciphercontext, cipher, passphrase,
 	    CIPHER_DECRYPT);
 	cipher_crypt(&ciphercontext, cp,
 	    buffer_ptr(&buffer), buffer_len(&buffer));
 	cipher_cleanup(&ciphercontext);
 	memset(&ciphercontext, 0, sizeof(ciphercontext));
 	buffer_free(&buffer);

 	check1 = buffer_get_char(&decrypted);
 	check2 = buffer_get_char(&decrypted);
 	if (check1 != buffer_get_char(&decrypted) ||
 	    check2 != buffer_get_char(&decrypted)) {
 		if (strcmp(passphrase, "") != 0)
 			debug("Bad passphrase supplied for key file %.200s.",
 			    filename);
 		/* Bad passphrase. */
 		buffer_free(&decrypted);
 		goto fail;
 	}
 	/* Read the rest of the private key. */
 	buffer_get_bignum(&decrypted, prv->rsa->d);
 	buffer_get_bignum(&decrypted, prv->rsa->iqmp);		/* u */
 	/* in SSL and SSH v1 p and q are exchanged */
 	buffer_get_bignum(&decrypted, prv->rsa->q);		/* p */
 	buffer_get_bignum(&decrypted, prv->rsa->p);		/* q */

 	/* calculate p-1 and q-1 */
 	rsa_generate_additional_parameters(prv->rsa);

 	buffer_free(&decrypted);

 	/* enable blinding */
 	if (RSA_blinding_on(prv->rsa, NULL) != 1) {
 		error("key_load_private_rsa1: RSA_blinding_on failed");
 		goto fail;
 	}
 	close(fd);
 	return prv;

 fail:
 	if (commentp)
 		xfree(*commentp);
 	close(fd);
 	key_free(prv);
 	return NULL;
 }

 Key *
 key_load_private_pem(int fd, int type, const char *passphrase,
     char **commentp)
 {
 	FILE *fp;
 	EVP_PKEY *pk = NULL;
 	Key *prv = NULL;
 	char *name = "<no key>";

 	fp = fdopen(fd, "r");
 	if (fp == NULL) {
 		error("fdopen failed: %s", strerror(errno));
 		close(fd);
 		return NULL;
 	}
 	pk = PEM_read_PrivateKey(fp, NULL, NULL, (char *)passphrase);
 	if (pk == NULL) {
 		debug("PEM_read_PrivateKey failed");
 		(void)ERR_get_error();
 	} else if (pk->type == EVP_PKEY_RSA &&
 	    (type == KEY_UNSPEC||type==KEY_RSA)) {
 		prv = key_new(KEY_UNSPEC);
 		prv->rsa = EVP_PKEY_get1_RSA(pk);
 		prv->type = KEY_RSA;
 		name = "rsa w/o comment";
 #ifdef DEBUG_PK
 		RSA_print_fp(stderr, prv->rsa, 8);
 #endif
 		if (RSA_blinding_on(prv->rsa, NULL) != 1) {
 			error("key_load_private_pem: RSA_blinding_on failed");
 			key_free(prv);
 			prv = NULL;
 		}
 	} else if (pk->type == EVP_PKEY_DSA &&
 	    (type == KEY_UNSPEC||type==KEY_DSA)) {
 		prv = key_new(KEY_UNSPEC);
 		prv->dsa = EVP_PKEY_get1_DSA(pk);
 		prv->type = KEY_DSA;
 		name = "dsa w/o comment";
 #ifdef DEBUG_PK
 		DSA_print_fp(stderr, prv->dsa, 8);
 #endif
 	} else {
 		error("PEM_read_PrivateKey: mismatch or "
 		    "unknown EVP_PKEY save_type %d", pk->save_type);
 	}
 	fclose(fp);
 	if (pk != NULL)
 		EVP_PKEY_free(pk);
 	if (prv != NULL && commentp)
 		*commentp = xstrdup(name);
 	debug("read PEM private key done: type %s",
 	    prv ? key_type(prv) : "<unknown>");
 	return prv;
 }

 int
 key_perm_ok(int fd, const char *filename)
 {
 	struct stat st;

 	if (fstat(fd, &st) < 0)
 		return 0;
 	/*
 	 * if a key owned by the user is accessed, then we check the
 	 * permissions of the file. if the key owned by a different user,
 	 * then we don't care.
 	 */
 #ifdef HAVE_CYGWIN
 	if (check_ntsec(filename))
 #endif
 	if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0) {
 		error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
 		error("@         WARNING: UNPROTECTED PRIVATE KEY FILE!          @");
 		error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
 		error("Permissions 0%3.3o for '%s' are too open.",
 		    (u_int)st.st_mode & 0777, filename);
 		error("It is recommended that your private key files are NOT accessible by others.");
 		error("This private key will be ignored.");
 		return 0;
 	}
 	return 1;
 }

 Key *
 key_load_private_type(int type, const char *filename, const char *passphrase,
     char **commentp, int *perm_ok)
 {
 	int fd;

 	fd = open(filename, O_RDONLY);
 	if (fd < 0)
 		return NULL;
 	if (!key_perm_ok(fd, filename)) {
 		if (perm_ok != NULL)
 			*perm_ok = 0;
 		error("bad permissions: ignore key: %s", filename);
 		close(fd);
 		return NULL;
 	}
 	if (perm_ok != NULL)
 		*perm_ok = 1;
 	switch (type) {
 	case KEY_RSA1:
 		return key_load_private_rsa1(fd, filename, passphrase,
 		    commentp);
 		/* closes fd */
 	case KEY_DSA:
 	case KEY_RSA:
 	case KEY_UNSPEC:
 		return key_load_private_pem(fd, type, passphrase, commentp);
 		/* closes fd */
 	default:
 		close(fd);
 		break;
 	}
 	return NULL;
 }

 Key *
 key_load_private(const char *filename, const char *passphrase,
     char **commentp)
 {
 	Key *pub, *prv;
 	int fd;

 	fd = open(filename, O_RDONLY);
 	if (fd < 0)
 		return NULL;
 	if (!key_perm_ok(fd, filename)) {
 		error("bad permissions: ignore key: %s", filename);
 		close(fd);
 		return NULL;
 	}
 	pub = key_load_public_rsa1(fd, filename, commentp);
 	lseek(fd, (off_t) 0, SEEK_SET);		/* rewind */
 	if (pub == NULL) {
 		/* closes fd */
 		prv = key_load_private_pem(fd, KEY_UNSPEC, passphrase, NULL);
 		/* use the filename as a comment for PEM */
 		if (commentp && prv)
 			*commentp = xstrdup(filename);
 	} else {
 		/* it's a SSH v1 key if the public key part is readable */
 		key_free(pub);
 		/* closes fd */
 		prv = key_load_private_rsa1(fd, filename, passphrase, NULL);
 	}
 	return prv;
 }

 static int
 key_try_load_public(Key *k, const char *filename, char **commentp)
 {
 	FILE *f;
 	char line[SSH_MAX_PUBKEY_BYTES];
 	char *cp;
 	u_long linenum = 0;

 	f = fopen(filename, "r");
 	if (f != NULL) {
 		while (read_keyfile_line(f, filename, line, sizeof(line),
 			    &linenum) != -1) {
 			cp = line;
 			switch (*cp) {
 			case '#':
 			case '\n':
 			case '\0':
 				continue;
 			}
 			/* Skip leading whitespace. */
 			for (; *cp && (*cp == ' ' || *cp == '\t'); cp++)
 				;
 			if (*cp) {
 				if (key_read(k, &cp) == 1) {
 					if (commentp)
 						*commentp=xstrdup(filename);
 					fclose(f);
 					return 1;
 				}
 			}
 		}
 		fclose(f);
 	}
 	return 0;
 }

 /* load public key from ssh v1 private or any pubkey file */
 Key *
 key_load_public(const char *filename, char **commentp)
 {
 	Key *pub;
 	char file[MAXPATHLEN];

 	/* try rsa1 private key */
 	pub = key_load_public_type(KEY_RSA1, filename, commentp);
 	if (pub != NULL)
 		return pub;

 	/* try rsa1 public key */
 	pub = key_new(KEY_RSA1);
 	if (key_try_load_public(pub, filename, commentp) == 1)
 		return pub;
 	key_free(pub);

 	/* try ssh2 public key */
 	pub = key_new(KEY_UNSPEC);
 	if (key_try_load_public(pub, filename, commentp) == 1)
 		return pub;
 	if ((strlcpy(file, filename, sizeof file) < sizeof(file)) &&
 	    (strlcat(file, ".pub", sizeof file) < sizeof(file)) &&
 	    (key_try_load_public(pub, file, commentp) == 1))
 		return pub;
 	key_free(pub);
 	return NULL;
 }
	/* $OpenBSD: authfile.c,v 1.71 2006/07/22 20:48:22 stevesk Exp $ */
	/*
	* Author: Tatu Ylonen <ylo@cs.hut.fi>
	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	* All rights reserved
	* This file contains functions for reading and writing identity files, and
	* for reading the passphrase from the user.
	*
	* 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) 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 <sys/stat.h>

	#include <openssl/err.h>
	#include <openssl/evp.h>
	#include <openssl/pem.h>

	#include <errno.h>
	#include <fcntl.h>
	#include <string.h>
	#include <unistd.h>

	#include "cipher.h"
	#include "xmalloc.h"
	#include "buffer.h"
	#include "bufaux.h"
	#include "key.h"
	#include "ssh.h"
	#include "log.h"
	#include "authfile.h"
	#include "rsa.h"
	#include "misc.h"
	#include "atomicio.h"

	/* Version identification string for SSH v1 identity files. */
	static const char authfile_id_string[] =
	"SSH PRIVATE KEY FILE FORMAT 1.1\n";

	/*
	* Saves the authentication (private) key in a file, encrypting it with
	* passphrase. The identification of the file (lowest 64 bits of n) will
	* precede the key to provide identification of the key without needing a
	* passphrase.
	*/

	static int
	key_save_private_rsa1(Key key, const char filename, const char *passphrase,
	const char *comment)
	{
	Buffer buffer, encrypted;
	u_char buf[100], *cp;
	int fd, i, cipher_num;
	CipherContext ciphercontext;
	Cipher *cipher;
	u_int32_t rnd;

	/*
	* If the passphrase is empty, use SSH_CIPHER_NONE to ease converting
	* to another cipher; otherwise use SSH_AUTHFILE_CIPHER.
	*/
	cipher_num = (strcmp(passphrase, "") == 0) ?
	SSH_CIPHER_NONE : SSH_AUTHFILE_CIPHER;
	if ((cipher = cipher_by_number(cipher_num)) == NULL)
	fatal("save_private_key_rsa: bad cipher");

	/* This buffer is used to built the secret part of the private key. */
	buffer_init(&buffer);

	/* Put checkbytes for checking passphrase validity. */
	rnd = arc4random();
	buf[0] = rnd & 0xff;
	buf[1] = (rnd >> 8) & 0xff;
	buf[2] = buf[0];
	buf[3] = buf[1];
	buffer_append(&buffer, buf, 4);

	/*
	* Store the private key (n and e will not be stored because they
	* will be stored in plain text, and storing them also in encrypted
	* format would just give known plaintext).
	*/
	buffer_put_bignum(&buffer, key->rsa->d);
	buffer_put_bignum(&buffer, key->rsa->iqmp);
	buffer_put_bignum(&buffer, key->rsa->q); /* reverse from SSL p */
	buffer_put_bignum(&buffer, key->rsa->p); /* reverse from SSL q */

	/* Pad the part to be encrypted until its size is a multiple of 8. */
	while (buffer_len(&buffer) % 8 != 0)
	buffer_put_char(&buffer, 0);

	/* This buffer will be used to contain the data in the file. */
	buffer_init(&encrypted);

	/* First store keyfile id string. */
	for (i = 0; authfile_id_string[i]; i++)
	buffer_put_char(&encrypted, authfile_id_string[i]);
	buffer_put_char(&encrypted, 0);

	/* Store cipher type. */
	buffer_put_char(&encrypted, cipher_num);
	buffer_put_int(&encrypted, 0); /* For future extension */

	/* Store public key. This will be in plain text. */
	buffer_put_int(&encrypted, BN_num_bits(key->rsa->n));
	buffer_put_bignum(&encrypted, key->rsa->n);
	buffer_put_bignum(&encrypted, key->rsa->e);
	buffer_put_cstring(&encrypted, comment);

	/* Allocate space for the private part of the key in the buffer. */
	cp = buffer_append_space(&encrypted, buffer_len(&buffer));

	cipher_set_key_string(&ciphercontext, cipher, passphrase,
	CIPHER_ENCRYPT);
	cipher_crypt(&ciphercontext, cp,
	buffer_ptr(&buffer), buffer_len(&buffer));
	cipher_cleanup(&ciphercontext);
	memset(&ciphercontext, 0, sizeof(ciphercontext));

	/* Destroy temporary data. */
	memset(buf, 0, sizeof(buf));
	buffer_free(&buffer);

	fd = open(filename, O_WRONLY \| O_CREAT \| O_TRUNC, 0600);
	if (fd < 0) {
	error("open %s failed: %s.", filename, strerror(errno));
	buffer_free(&encrypted);
	return 0;
	}
	if (atomicio(vwrite, fd, buffer_ptr(&encrypted),
	buffer_len(&encrypted)) != buffer_len(&encrypted)) {
	error("write to key file %s failed: %s", filename,
	strerror(errno));
	buffer_free(&encrypted);
	close(fd);
	unlink(filename);
	return 0;
	}
	close(fd);
	buffer_free(&encrypted);
	return 1;
	}

	/* save SSH v2 key in OpenSSL PEM format */
	static int
	key_save_private_pem(Key key, const char filename, const char *_passphrase,
	const char *comment)
	{
	FILE *fp;
	int fd;
	int success = 0;
	int len = strlen(_passphrase);
	u_char passphrase = (len > 0) ? (u_char )_passphrase : NULL;
	const EVP_CIPHER *cipher = (len > 0) ? EVP_des_ede3_cbc() : NULL;

	if (len > 0 && len <= 4) {
	error("passphrase too short: have %d bytes, need > 4", len);
	return 0;
	}
	fd = open(filename, O_WRONLY \| O_CREAT \| O_TRUNC, 0600);
	if (fd < 0) {
	error("open %s failed: %s.", filename, strerror(errno));
	return 0;
	}
	fp = fdopen(fd, "w");
	if (fp == NULL ) {
	error("fdopen %s failed: %s.", filename, strerror(errno));
	close(fd);
	return 0;
	}
	switch (key->type) {
	case KEY_DSA:
	success = PEM_write_DSAPrivateKey(fp, key->dsa,
	cipher, passphrase, len, NULL, NULL);
	break;
	case KEY_RSA:
	success = PEM_write_RSAPrivateKey(fp, key->rsa,
	cipher, passphrase, len, NULL, NULL);
	break;
	}
	fclose(fp);
	return success;
	}

	int
	key_save_private(Key key, const char filename, const char *passphrase,
	const char *comment)
	{
	switch (key->type) {
	case KEY_RSA1:
	return key_save_private_rsa1(key, filename, passphrase,
	comment);
	case KEY_DSA:
	case KEY_RSA:
	return key_save_private_pem(key, filename, passphrase,
	comment);
	default:
	break;
	}
	error("key_save_private: cannot save key type %d", key->type);
	return 0;
	}

	/*
	* Loads the public part of the ssh v1 key file. Returns NULL if an error was
	* encountered (the file does not exist or is not readable), and the key
	* otherwise.
	*/

	static Key *
	key_load_public_rsa1(int fd, const char filename, char *commentp)
	{
	Buffer buffer;
	Key *pub;
	struct stat st;
	char *cp;
	u_int i;
	size_t len;

	if (fstat(fd, &st) < 0) {
	error("fstat for key file %.200s failed: %.100s",
	filename, strerror(errno));
	return NULL;
	}
	if (st.st_size > 110241024) {
	error("key file %.200s too large", filename);
	return NULL;
	}
	len = (size_t)st.st_size; /* truncated */

	buffer_init(&buffer);
	cp = buffer_append_space(&buffer, len);

	if (atomicio(read, fd, cp, len) != len) {
	debug("Read from key file %.200s failed: %.100s", filename,
	strerror(errno));
	buffer_free(&buffer);
	return NULL;
	}

	/* Check that it is at least big enough to contain the ID string. */
	if (len < sizeof(authfile_id_string)) {
	debug3("Not a RSA1 key file %.200s.", filename);
	buffer_free(&buffer);
	return NULL;
	}
	/*
	* Make sure it begins with the id string. Consume the id string
	* from the buffer.
	*/
	for (i = 0; i < sizeof(authfile_id_string); i++)
	if (buffer_get_char(&buffer) != authfile_id_string[i]) {
	debug3("Not a RSA1 key file %.200s.", filename);
	buffer_free(&buffer);
	return NULL;
	}
	/* Skip cipher type and reserved data. */
	(void) buffer_get_char(&buffer); /* cipher type */
	(void) buffer_get_int(&buffer); /* reserved */

	/* Read the public key from the buffer. */
	(void) buffer_get_int(&buffer);
	pub = key_new(KEY_RSA1);
	buffer_get_bignum(&buffer, pub->rsa->n);
	buffer_get_bignum(&buffer, pub->rsa->e);
	if (commentp)
	*commentp = buffer_get_string(&buffer, NULL);
	/* The encrypted private part is not parsed by this function. */

	buffer_free(&buffer);
	return pub;
	}

	/* load public key from private-key file, works only for SSH v1 */
	Key *
	key_load_public_type(int type, const char filename, char *commentp)
	{
	Key *pub;
	int fd;

	if (type == KEY_RSA1) {
	fd = open(filename, O_RDONLY);
	if (fd < 0)
	return NULL;
	pub = key_load_public_rsa1(fd, filename, commentp);
	close(fd);
	return pub;
	}
	return NULL;
	}

	/*
	* Loads the private key from the file. Returns 0 if an error is encountered
	* (file does not exist or is not readable, or passphrase is bad). This
	* initializes the private key.
	* Assumes we are called under uid of the owner of the file.
	*/

	static Key *
	key_load_private_rsa1(int fd, const char filename, const char passphrase,
	char **commentp)
	{
	u_int i;
	int check1, check2, cipher_type;
	size_t len;
	Buffer buffer, decrypted;
	u_char *cp;
	CipherContext ciphercontext;
	Cipher *cipher;
	Key *prv = NULL;
	struct stat st;

	if (fstat(fd, &st) < 0) {
	error("fstat for key file %.200s failed: %.100s",
	filename, strerror(errno));
	close(fd);
	return NULL;
	}
	if (st.st_size > 110241024) {
	error("key file %.200s too large", filename);
	close(fd);
	return (NULL);
	}
	len = (size_t)st.st_size; /* truncated */

	buffer_init(&buffer);
	cp = buffer_append_space(&buffer, len);

	if (atomicio(read, fd, cp, len) != len) {
	debug("Read from key file %.200s failed: %.100s", filename,
	strerror(errno));
	buffer_free(&buffer);
	close(fd);
	return NULL;
	}

	/* Check that it is at least big enough to contain the ID string. */
	if (len < sizeof(authfile_id_string)) {
	debug3("Not a RSA1 key file %.200s.", filename);
	buffer_free(&buffer);
	close(fd);
	return NULL;
	}
	/*
	* Make sure it begins with the id string. Consume the id string
	* from the buffer.
	*/
	for (i = 0; i < sizeof(authfile_id_string); i++)
	if (buffer_get_char(&buffer) != authfile_id_string[i]) {
	debug3("Not a RSA1 key file %.200s.", filename);
	buffer_free(&buffer);
	close(fd);
	return NULL;
	}

	/* Read cipher type. */
	cipher_type = buffer_get_char(&buffer);
	(void) buffer_get_int(&buffer); /* Reserved data. */

	/* Read the public key from the buffer. */
	(void) buffer_get_int(&buffer);
	prv = key_new_private(KEY_RSA1);

	buffer_get_bignum(&buffer, prv->rsa->n);
	buffer_get_bignum(&buffer, prv->rsa->e);
	if (commentp)
	*commentp = buffer_get_string(&buffer, NULL);
	else
	xfree(buffer_get_string(&buffer, NULL));

	/* Check that it is a supported cipher. */
	cipher = cipher_by_number(cipher_type);
	if (cipher == NULL) {
	debug("Unsupported cipher %d used in key file %.200s.",
	cipher_type, filename);
	buffer_free(&buffer);
	goto fail;
	}
	/* Initialize space for decrypted data. */
	buffer_init(&decrypted);
	cp = buffer_append_space(&decrypted, buffer_len(&buffer));

	/* Rest of the buffer is encrypted. Decrypt it using the passphrase. */
	cipher_set_key_string(&ciphercontext, cipher, passphrase,
	CIPHER_DECRYPT);
	cipher_crypt(&ciphercontext, cp,
	buffer_ptr(&buffer), buffer_len(&buffer));
	cipher_cleanup(&ciphercontext);
	memset(&ciphercontext, 0, sizeof(ciphercontext));
	buffer_free(&buffer);

	check1 = buffer_get_char(&decrypted);
	check2 = buffer_get_char(&decrypted);
	if (check1 != buffer_get_char(&decrypted) \|\|
	check2 != buffer_get_char(&decrypted)) {
	if (strcmp(passphrase, "") != 0)
	debug("Bad passphrase supplied for key file %.200s.",
	filename);
	/* Bad passphrase. */
	buffer_free(&decrypted);
	goto fail;
	}
	/* Read the rest of the private key. */
	buffer_get_bignum(&decrypted, prv->rsa->d);
	buffer_get_bignum(&decrypted, prv->rsa->iqmp); /* u */
	/* in SSL and SSH v1 p and q are exchanged */
	buffer_get_bignum(&decrypted, prv->rsa->q); /* p */
	buffer_get_bignum(&decrypted, prv->rsa->p); /* q */

	/* calculate p-1 and q-1 */
	rsa_generate_additional_parameters(prv->rsa);

	buffer_free(&decrypted);

	/* enable blinding */
	if (RSA_blinding_on(prv->rsa, NULL) != 1) {
	error("key_load_private_rsa1: RSA_blinding_on failed");
	goto fail;
	}
	close(fd);
	return prv;

	fail:
	if (commentp)
	xfree(*commentp);
	close(fd);
	key_free(prv);
	return NULL;
	}

	Key *
	key_load_private_pem(int fd, int type, const char *passphrase,
	char **commentp)
	{
	FILE *fp;
	EVP_PKEY *pk = NULL;
	Key *prv = NULL;
	char *name = "<no key>";

	fp = fdopen(fd, "r");
	if (fp == NULL) {
	error("fdopen failed: %s", strerror(errno));
	close(fd);
	return NULL;
	}
	pk = PEM_read_PrivateKey(fp, NULL, NULL, (char *)passphrase);
	if (pk == NULL) {
	debug("PEM_read_PrivateKey failed");
	(void)ERR_get_error();
	} else if (pk->type == EVP_PKEY_RSA &&
	(type == KEY_UNSPEC\|\|type==KEY_RSA)) {
	prv = key_new(KEY_UNSPEC);
	prv->rsa = EVP_PKEY_get1_RSA(pk);
	prv->type = KEY_RSA;
	name = "rsa w/o comment";
	#ifdef DEBUG_PK
	RSA_print_fp(stderr, prv->rsa, 8);
	#endif
	if (RSA_blinding_on(prv->rsa, NULL) != 1) {
	error("key_load_private_pem: RSA_blinding_on failed");
	key_free(prv);
	prv = NULL;
	}
	} else if (pk->type == EVP_PKEY_DSA &&
	(type == KEY_UNSPEC\|\|type==KEY_DSA)) {
	prv = key_new(KEY_UNSPEC);
	prv->dsa = EVP_PKEY_get1_DSA(pk);
	prv->type = KEY_DSA;
	name = "dsa w/o comment";
	#ifdef DEBUG_PK
	DSA_print_fp(stderr, prv->dsa, 8);
	#endif
	} else {
	error("PEM_read_PrivateKey: mismatch or "
	"unknown EVP_PKEY save_type %d", pk->save_type);
	}
	fclose(fp);
	if (pk != NULL)
	EVP_PKEY_free(pk);
	if (prv != NULL && commentp)
	*commentp = xstrdup(name);
	debug("read PEM private key done: type %s",
	prv ? key_type(prv) : "<unknown>");
	return prv;
	}

	int
	key_perm_ok(int fd, const char *filename)
	{
	struct stat st;

	if (fstat(fd, &st) < 0)
	return 0;
	/*
	* if a key owned by the user is accessed, then we check the
	* permissions of the file. if the key owned by a different user,
	* then we don't care.
	*/
	#ifdef HAVE_CYGWIN
	if (check_ntsec(filename))
	#endif
	if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0) {
	error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
	error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @");
	error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
	error("Permissions 0%3.3o for '%s' are too open.",
	(u_int)st.st_mode & 0777, filename);
	error("It is recommended that your private key files are NOT accessible by others.");
	error("This private key will be ignored.");
	return 0;
	}
	return 1;
	}

	Key *
	key_load_private_type(int type, const char filename, const char passphrase,
	char *commentp, int perm_ok)
	{
	int fd;

	fd = open(filename, O_RDONLY);
	if (fd < 0)
	return NULL;
	if (!key_perm_ok(fd, filename)) {
	if (perm_ok != NULL)
	*perm_ok = 0;
	error("bad permissions: ignore key: %s", filename);
	close(fd);
	return NULL;
	}
	if (perm_ok != NULL)
	*perm_ok = 1;
	switch (type) {
	case KEY_RSA1:
	return key_load_private_rsa1(fd, filename, passphrase,
	commentp);
	/* closes fd */
	case KEY_DSA:
	case KEY_RSA:
	case KEY_UNSPEC:
	return key_load_private_pem(fd, type, passphrase, commentp);
	/* closes fd */
	default:
	close(fd);
	break;
	}
	return NULL;
	}

	Key *
	key_load_private(const char filename, const char passphrase,
	char **commentp)
	{
	Key pub, prv;
	int fd;

	fd = open(filename, O_RDONLY);
	if (fd < 0)
	return NULL;
	if (!key_perm_ok(fd, filename)) {
	error("bad permissions: ignore key: %s", filename);
	close(fd);
	return NULL;
	}
	pub = key_load_public_rsa1(fd, filename, commentp);
	lseek(fd, (off_t) 0, SEEK_SET); /* rewind */
	if (pub == NULL) {
	/* closes fd */
	prv = key_load_private_pem(fd, KEY_UNSPEC, passphrase, NULL);
	/* use the filename as a comment for PEM */
	if (commentp && prv)
	*commentp = xstrdup(filename);
	} else {
	/* it's a SSH v1 key if the public key part is readable */
	key_free(pub);
	/* closes fd */
	prv = key_load_private_rsa1(fd, filename, passphrase, NULL);
	}
	return prv;
	}

	static int
	key_try_load_public(Key k, const char filename, char **commentp)
	{
	FILE *f;
	char line[SSH_MAX_PUBKEY_BYTES];
	char *cp;
	u_long linenum = 0;

	f = fopen(filename, "r");
	if (f != NULL) {
	while (read_keyfile_line(f, filename, line, sizeof(line),
	&linenum) != -1) {
	cp = line;
	switch (*cp) {
	case '#':
	case '\n':
	case '\0':
	continue;
	}
	/* Skip leading whitespace. */
	for (; cp && (cp == ' ' \|\| *cp == '\t'); cp++)
	;
	if (*cp) {
	if (key_read(k, &cp) == 1) {
	if (commentp)
	*commentp=xstrdup(filename);
	fclose(f);
	return 1;
	}
	}
	}
	fclose(f);
	}
	return 0;
	}

	/* load public key from ssh v1 private or any pubkey file */
	Key *
	key_load_public(const char filename, char *commentp)
	{
	Key *pub;
	char file[MAXPATHLEN];

	/* try rsa1 private key */
	pub = key_load_public_type(KEY_RSA1, filename, commentp);
	if (pub != NULL)
	return pub;

	/* try rsa1 public key */
	pub = key_new(KEY_RSA1);
	if (key_try_load_public(pub, filename, commentp) == 1)
	return pub;
	key_free(pub);

	/* try ssh2 public key */
	pub = key_new(KEY_UNSPEC);
	if (key_try_load_public(pub, filename, commentp) == 1)
	return pub;
	if ((strlcpy(file, filename, sizeof file) < sizeof(file)) &&
	(strlcat(file, ".pub", sizeof file) < sizeof(file)) &&
	(key_try_load_public(pub, file, commentp) == 1))
	return pub;
	key_free(pub);
	return NULL;
	}