[gssapi-openssh.git] / openssh / authfile.c

/*
 * 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"
RCSID("$OpenBSD: authfile.c,v 1.61 2005/06/17 02:44:32 djm Exp $");

#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/pem.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);
		break;
	case KEY_DSA:
	case KEY_RSA:
		return key_save_private_pem(key, filename, passphrase,
		    comment);
		break;
	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;
}

static 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 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;
	}
	switch (type) {
	case KEY_RSA1:
		return key_load_private_rsa1(fd, filename, passphrase,
		    commentp);
		/* closes fd */
		break;
	case KEY_DSA:
	case KEY_RSA:
	case KEY_UNSPEC:
		return key_load_private_pem(fd, type, passphrase, commentp);
		/* closes fd */
		break;
	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;
}
Commit	Line	Data
3c0ef626	1	/*
	2	* Author: Tatu Ylonen <ylo@cs.hut.fi>
	3	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	4	* All rights reserved
	5	* This file contains functions for reading and writing identity files, and
	6	* for reading the passphrase from the user.
	7	*
	8	* As far as I am concerned, the code I have written for this software
	9	* can be used freely for any purpose. Any derived versions of this
	10	* software must be clearly marked as such, and if the derived work is
	11	* incompatible with the protocol description in the RFC file, it must be
	12	* called by a name other than "ssh" or "Secure Shell".
	13	*
	14	*
	15	* Copyright (c) 2000 Markus Friedl. All rights reserved.
	16	*
	17	* Redistribution and use in source and binary forms, with or without
	18	* modification, are permitted provided that the following conditions
	19	* are met:
	20	* 1. Redistributions of source code must retain the above copyright
	21	* notice, this list of conditions and the following disclaimer.
	22	* 2. Redistributions in binary form must reproduce the above copyright
	23	* notice, this list of conditions and the following disclaimer in the
	24	* documentation and/or other materials provided with the distribution.
	25	*
	26	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	27	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	28	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	29	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	30	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	31	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	32	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	33	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	34	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	35	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	36	*/
	37
	38	#include "includes.h"
665a873d	39	RCSID("$OpenBSD: authfile.c,v 1.61 2005/06/17 02:44:32 djm Exp $");
3c0ef626	40
	41	#include <openssl/err.h>
	42	#include <openssl/evp.h>
	43	#include <openssl/pem.h>
	44
	45	#include "cipher.h"
	46	#include "xmalloc.h"
	47	#include "buffer.h"
	48	#include "bufaux.h"
	49	#include "key.h"
	50	#include "ssh.h"
	51	#include "log.h"
	52	#include "authfile.h"
e9a17296	53	#include "rsa.h"
996d5e62	54	#include "misc.h"
665a873d	55	#include "atomicio.h"
3c0ef626	56
	57	/* Version identification string for SSH v1 identity files. */
	58	static const char authfile_id_string[] =
	59	"SSH PRIVATE KEY FILE FORMAT 1.1\n";
	60
	61	/*
	62	* Saves the authentication (private) key in a file, encrypting it with
	63	* passphrase. The identification of the file (lowest 64 bits of n) will
	64	* precede the key to provide identification of the key without needing a
	65	* passphrase.
	66	*/
	67
	68	static int
	69	key_save_private_rsa1(Key key, const char filename, const char *passphrase,
	70	const char *comment)
	71	{
	72	Buffer buffer, encrypted;
e9a17296	73	u_char buf[100], *cp;
e9a17296	74	int fd, i, cipher_num;
3c0ef626	75	CipherContext ciphercontext;
3c0ef626	76	Cipher *cipher;
c9f39d2c	77	u_int32_t rnd;
3c0ef626	78
	79	/*
	80	* If the passphrase is empty, use SSH_CIPHER_NONE to ease converting
	81	* to another cipher; otherwise use SSH_AUTHFILE_CIPHER.
	82	*/
e9a17296	83	cipher_num = (strcmp(passphrase, "") == 0) ?
	84	SSH_CIPHER_NONE : SSH_AUTHFILE_CIPHER;
	85	if ((cipher = cipher_by_number(cipher_num)) == NULL)
3c0ef626	86	fatal("save_private_key_rsa: bad cipher");
	87
	88	/* This buffer is used to built the secret part of the private key. */
	89	buffer_init(&buffer);
	90
	91	/* Put checkbytes for checking passphrase validity. */
c9f39d2c	92	rnd = arc4random();
	93	buf[0] = rnd & 0xff;
	94	buf[1] = (rnd >> 8) & 0xff;
3c0ef626	95	buf[2] = buf[0];
	96	buf[3] = buf[1];
	97	buffer_append(&buffer, buf, 4);
	98
	99	/*
	100	* Store the private key (n and e will not be stored because they
	101	* will be stored in plain text, and storing them also in encrypted
	102	* format would just give known plaintext).
	103	*/
	104	buffer_put_bignum(&buffer, key->rsa->d);
	105	buffer_put_bignum(&buffer, key->rsa->iqmp);
	106	buffer_put_bignum(&buffer, key->rsa->q); /* reverse from SSL p */
	107	buffer_put_bignum(&buffer, key->rsa->p); /* reverse from SSL q */
	108
	109	/* Pad the part to be encrypted until its size is a multiple of 8. */
	110	while (buffer_len(&buffer) % 8 != 0)
	111	buffer_put_char(&buffer, 0);
	112
	113	/* This buffer will be used to contain the data in the file. */
	114	buffer_init(&encrypted);
	115
	116	/* First store keyfile id string. */
	117	for (i = 0; authfile_id_string[i]; i++)
	118	buffer_put_char(&encrypted, authfile_id_string[i]);
	119	buffer_put_char(&encrypted, 0);
	120
	121	/* Store cipher type. */
e9a17296	122	buffer_put_char(&encrypted, cipher_num);
3c0ef626	123	buffer_put_int(&encrypted, 0); /* For future extension */
	124
	125	/* Store public key. This will be in plain text. */
	126	buffer_put_int(&encrypted, BN_num_bits(key->rsa->n));
	127	buffer_put_bignum(&encrypted, key->rsa->n);
	128	buffer_put_bignum(&encrypted, key->rsa->e);
	129	buffer_put_cstring(&encrypted, comment);
	130
	131	/* Allocate space for the private part of the key in the buffer. */
e9a17296	132	cp = buffer_append_space(&encrypted, buffer_len(&buffer));
3c0ef626	133
e9a17296	134	cipher_set_key_string(&ciphercontext, cipher, passphrase,
	135	CIPHER_ENCRYPT);
	136	cipher_crypt(&ciphercontext, cp,
	137	buffer_ptr(&buffer), buffer_len(&buffer));
	138	cipher_cleanup(&ciphercontext);
3c0ef626	139	memset(&ciphercontext, 0, sizeof(ciphercontext));
	140
	141	/* Destroy temporary data. */
	142	memset(buf, 0, sizeof(buf));
	143	buffer_free(&buffer);
	144
	145	fd = open(filename, O_WRONLY \| O_CREAT \| O_TRUNC, 0600);
	146	if (fd < 0) {
	147	error("open %s failed: %s.", filename, strerror(errno));
cdd66111	148	buffer_free(&encrypted);
3c0ef626	149	return 0;
3c0ef626	150	}
665a873d	151	if (atomicio(vwrite, fd, buffer_ptr(&encrypted),
665a873d	152	buffer_len(&encrypted)) != buffer_len(&encrypted)) {
3c0ef626	153	error("write to key file %s failed: %s", filename,
e9a17296	154	strerror(errno));
3c0ef626	155	buffer_free(&encrypted);
	156	close(fd);
	157	unlink(filename);
	158	return 0;
	159	}
	160	close(fd);
	161	buffer_free(&encrypted);
	162	return 1;
	163	}
	164
	165	/* save SSH v2 key in OpenSSL PEM format */
	166	static int
	167	key_save_private_pem(Key key, const char filename, const char *_passphrase,
	168	const char *comment)
	169	{
	170	FILE *fp;
	171	int fd;
	172	int success = 0;
	173	int len = strlen(_passphrase);
e9a17296	174	u_char passphrase = (len > 0) ? (u_char )_passphrase : NULL;
e9a17296	175	const EVP_CIPHER *cipher = (len > 0) ? EVP_des_ede3_cbc() : NULL;
3c0ef626	176
	177	if (len > 0 && len <= 4) {
	178	error("passphrase too short: have %d bytes, need > 4", len);
	179	return 0;
	180	}
	181	fd = open(filename, O_WRONLY \| O_CREAT \| O_TRUNC, 0600);
	182	if (fd < 0) {
	183	error("open %s failed: %s.", filename, strerror(errno));
	184	return 0;
	185	}
	186	fp = fdopen(fd, "w");
	187	if (fp == NULL ) {
	188	error("fdopen %s failed: %s.", filename, strerror(errno));
	189	close(fd);
	190	return 0;
	191	}
	192	switch (key->type) {
	193	case KEY_DSA:
	194	success = PEM_write_DSAPrivateKey(fp, key->dsa,
	195	cipher, passphrase, len, NULL, NULL);
	196	break;
	197	case KEY_RSA:
	198	success = PEM_write_RSAPrivateKey(fp, key->rsa,
	199	cipher, passphrase, len, NULL, NULL);
	200	break;
	201	}
	202	fclose(fp);
	203	return success;
	204	}
	205
	206	int
	207	key_save_private(Key key, const char filename, const char *passphrase,
	208	const char *comment)
	209	{
	210	switch (key->type) {
	211	case KEY_RSA1:
	212	return key_save_private_rsa1(key, filename, passphrase,
	213	comment);
	214	break;
	215	case KEY_DSA:
	216	case KEY_RSA:
	217	return key_save_private_pem(key, filename, passphrase,
	218	comment);
	219	break;
	220	default:
	221	break;
	222	}
	223	error("key_save_private: cannot save key type %d", key->type);
	224	return 0;
	225	}
	226
	227	/*
	228	* Loads the public part of the ssh v1 key file. Returns NULL if an error was
	229	* encountered (the file does not exist or is not readable), and the key
	230	* otherwise.
	231	*/
	232
	233	static Key *
	234	key_load_public_rsa1(int fd, const char filename, char *commentp)
	235	{
	236	Buffer buffer;
	237	Key *pub;
6a9b3198	238	struct stat st;
3c0ef626	239	char *cp;
665a873d	240	u_int i;
c9f39d2c	241	size_t len;
3c0ef626	242
6a9b3198	243	if (fstat(fd, &st) < 0) {
	244	error("fstat for key file %.200s failed: %.100s",
	245	filename, strerror(errno));
	246	return NULL;
	247	}
996d5e62	248	if (st.st_size > 110241024) {
	249	error("key file %.200s too large", filename);
	250	return NULL;
	251	}
c9f39d2c	252	len = (size_t)st.st_size; /* truncated */
3c0ef626	253
3c0ef626	254	buffer_init(&buffer);
e9a17296	255	cp = buffer_append_space(&buffer, len);
3c0ef626	256
665a873d	257	if (atomicio(read, fd, cp, len) != len) {
3c0ef626	258	debug("Read from key file %.200s failed: %.100s", filename,
	259	strerror(errno));
	260	buffer_free(&buffer);
	261	return NULL;
	262	}
	263
	264	/* Check that it is at least big enough to contain the ID string. */
	265	if (len < sizeof(authfile_id_string)) {
	266	debug3("Not a RSA1 key file %.200s.", filename);
	267	buffer_free(&buffer);
	268	return NULL;
	269	}
	270	/*
	271	* Make sure it begins with the id string. Consume the id string
	272	* from the buffer.
	273	*/
	274	for (i = 0; i < sizeof(authfile_id_string); i++)
	275	if (buffer_get_char(&buffer) != authfile_id_string[i]) {
	276	debug3("Not a RSA1 key file %.200s.", filename);
	277	buffer_free(&buffer);
	278	return NULL;
	279	}
	280	/* Skip cipher type and reserved data. */
	281	(void) buffer_get_char(&buffer); /* cipher type */
	282	(void) buffer_get_int(&buffer); /* reserved */
	283
	284	/* Read the public key from the buffer. */
680cee3b	285	(void) buffer_get_int(&buffer);
3c0ef626	286	pub = key_new(KEY_RSA1);
	287	buffer_get_bignum(&buffer, pub->rsa->n);
	288	buffer_get_bignum(&buffer, pub->rsa->e);
	289	if (commentp)
	290	*commentp = buffer_get_string(&buffer, NULL);
	291	/* The encrypted private part is not parsed by this function. */
	292
	293	buffer_free(&buffer);
	294	return pub;
	295	}
	296
	297	/* load public key from private-key file, works only for SSH v1 */
	298	Key *
	299	key_load_public_type(int type, const char filename, char *commentp)
	300	{
	301	Key *pub;
	302	int fd;
	303
	304	if (type == KEY_RSA1) {
	305	fd = open(filename, O_RDONLY);
	306	if (fd < 0)
	307	return NULL;
	308	pub = key_load_public_rsa1(fd, filename, commentp);
	309	close(fd);
	310	return pub;
	311	}
	312	return NULL;
	313	}
	314
	315	/*
	316	* Loads the private key from the file. Returns 0 if an error is encountered
	317	* (file does not exist or is not readable, or passphrase is bad). This
	318	* initializes the private key.
	319	* Assumes we are called under uid of the owner of the file.
	320	*/
	321
	322	static Key *
	323	key_load_private_rsa1(int fd, const char filename, const char passphrase,
	324	char **commentp)
	325	{
665a873d	326	u_int i;
665a873d	327	int check1, check2, cipher_type;
c9f39d2c	328	size_t len;
3c0ef626	329	Buffer buffer, decrypted;
e9a17296	330	u_char *cp;
3c0ef626	331	CipherContext ciphercontext;
3c0ef626	332	Cipher *cipher;
3c0ef626	333	Key *prv = NULL;
6a9b3198	334	struct stat st;
3c0ef626	335
6a9b3198	336	if (fstat(fd, &st) < 0) {
	337	error("fstat for key file %.200s failed: %.100s",
	338	filename, strerror(errno));
	339	close(fd);
	340	return NULL;
	341	}
c9f39d2c	342	if (st.st_size > 110241024) {
996d5e62	343	error("key file %.200s too large", filename);
c9f39d2c	344	close(fd);
	345	return (NULL);
	346	}
	347	len = (size_t)st.st_size; /* truncated */
3c0ef626	348
3c0ef626	349	buffer_init(&buffer);
e9a17296	350	cp = buffer_append_space(&buffer, len);
3c0ef626	351
665a873d	352	if (atomicio(read, fd, cp, len) != len) {
3c0ef626	353	debug("Read from key file %.200s failed: %.100s", filename,
	354	strerror(errno));
	355	buffer_free(&buffer);
	356	close(fd);
	357	return NULL;
	358	}
	359
	360	/* Check that it is at least big enough to contain the ID string. */
	361	if (len < sizeof(authfile_id_string)) {
	362	debug3("Not a RSA1 key file %.200s.", filename);
	363	buffer_free(&buffer);
	364	close(fd);
	365	return NULL;
	366	}
	367	/*
	368	* Make sure it begins with the id string. Consume the id string
	369	* from the buffer.
	370	*/
	371	for (i = 0; i < sizeof(authfile_id_string); i++)
	372	if (buffer_get_char(&buffer) != authfile_id_string[i]) {
	373	debug3("Not a RSA1 key file %.200s.", filename);
	374	buffer_free(&buffer);
	375	close(fd);
	376	return NULL;
	377	}
	378
	379	/* Read cipher type. */
	380	cipher_type = buffer_get_char(&buffer);
	381	(void) buffer_get_int(&buffer); /* Reserved data. */
	382
	383	/* Read the public key from the buffer. */
680cee3b	384	(void) buffer_get_int(&buffer);
3c0ef626	385	prv = key_new_private(KEY_RSA1);
	386
	387	buffer_get_bignum(&buffer, prv->rsa->n);
	388	buffer_get_bignum(&buffer, prv->rsa->e);
	389	if (commentp)
	390	*commentp = buffer_get_string(&buffer, NULL);
	391	else
	392	xfree(buffer_get_string(&buffer, NULL));
	393
	394	/* Check that it is a supported cipher. */
	395	cipher = cipher_by_number(cipher_type);
	396	if (cipher == NULL) {
	397	debug("Unsupported cipher %d used in key file %.200s.",
	398	cipher_type, filename);
	399	buffer_free(&buffer);
	400	goto fail;
	401	}
	402	/* Initialize space for decrypted data. */
	403	buffer_init(&decrypted);
e9a17296	404	cp = buffer_append_space(&decrypted, buffer_len(&buffer));
3c0ef626	405
3c0ef626	406	/* Rest of the buffer is encrypted. Decrypt it using the passphrase. */
e9a17296	407	cipher_set_key_string(&ciphercontext, cipher, passphrase,
	408	CIPHER_DECRYPT);
	409	cipher_crypt(&ciphercontext, cp,
	410	buffer_ptr(&buffer), buffer_len(&buffer));
	411	cipher_cleanup(&ciphercontext);
3c0ef626	412	memset(&ciphercontext, 0, sizeof(ciphercontext));
	413	buffer_free(&buffer);
	414
	415	check1 = buffer_get_char(&decrypted);
	416	check2 = buffer_get_char(&decrypted);
	417	if (check1 != buffer_get_char(&decrypted) \|\|
	418	check2 != buffer_get_char(&decrypted)) {
	419	if (strcmp(passphrase, "") != 0)
	420	debug("Bad passphrase supplied for key file %.200s.",
	421	filename);
	422	/* Bad passphrase. */
	423	buffer_free(&decrypted);
	424	goto fail;
	425	}
	426	/* Read the rest of the private key. */
	427	buffer_get_bignum(&decrypted, prv->rsa->d);
	428	buffer_get_bignum(&decrypted, prv->rsa->iqmp); /* u */
	429	/* in SSL and SSH v1 p and q are exchanged */
	430	buffer_get_bignum(&decrypted, prv->rsa->q); /* p */
	431	buffer_get_bignum(&decrypted, prv->rsa->p); /* q */
	432
	433	/* calculate p-1 and q-1 */
e9a17296	434	rsa_generate_additional_parameters(prv->rsa);
3c0ef626	435
3c0ef626	436	buffer_free(&decrypted);
6a9b3198	437
	438	/* enable blinding */
	439	if (RSA_blinding_on(prv->rsa, NULL) != 1) {
	440	error("key_load_private_rsa1: RSA_blinding_on failed");
	441	goto fail;
	442	}
3c0ef626	443	close(fd);
	444	return prv;
	445
	446	fail:
	447	if (commentp)
	448	xfree(*commentp);
	449	close(fd);
	450	key_free(prv);
	451	return NULL;
	452	}
	453
f5799ae1	454	Key *
3c0ef626	455	key_load_private_pem(int fd, int type, const char *passphrase,
	456	char **commentp)
	457	{
	458	FILE *fp;
	459	EVP_PKEY *pk = NULL;
	460	Key *prv = NULL;
	461	char *name = "<no key>";
	462
	463	fp = fdopen(fd, "r");
	464	if (fp == NULL) {
	465	error("fdopen failed: %s", strerror(errno));
	466	close(fd);
	467	return NULL;
	468	}
	469	pk = PEM_read_PrivateKey(fp, NULL, NULL, (char *)passphrase);
	470	if (pk == NULL) {
	471	debug("PEM_read_PrivateKey failed");
	472	(void)ERR_get_error();
	473	} else if (pk->type == EVP_PKEY_RSA &&
e9a17296	474	(type == KEY_UNSPEC\|\|type==KEY_RSA)) {
3c0ef626	475	prv = key_new(KEY_UNSPEC);
	476	prv->rsa = EVP_PKEY_get1_RSA(pk);
	477	prv->type = KEY_RSA;
	478	name = "rsa w/o comment";
	479	#ifdef DEBUG_PK
	480	RSA_print_fp(stderr, prv->rsa, 8);
	481	#endif
6a9b3198	482	if (RSA_blinding_on(prv->rsa, NULL) != 1) {
	483	error("key_load_private_pem: RSA_blinding_on failed");
	484	key_free(prv);
	485	prv = NULL;
	486	}
3c0ef626	487	} else if (pk->type == EVP_PKEY_DSA &&
e9a17296	488	(type == KEY_UNSPEC\|\|type==KEY_DSA)) {
3c0ef626	489	prv = key_new(KEY_UNSPEC);
	490	prv->dsa = EVP_PKEY_get1_DSA(pk);
	491	prv->type = KEY_DSA;
	492	name = "dsa w/o comment";
	493	#ifdef DEBUG_PK
	494	DSA_print_fp(stderr, prv->dsa, 8);
	495	#endif
	496	} else {
	497	error("PEM_read_PrivateKey: mismatch or "
	498	"unknown EVP_PKEY save_type %d", pk->save_type);
	499	}
	500	fclose(fp);
	501	if (pk != NULL)
	502	EVP_PKEY_free(pk);
	503	if (prv != NULL && commentp)
	504	*commentp = xstrdup(name);
	505	debug("read PEM private key done: type %s",
	506	prv ? key_type(prv) : "<unknown>");
	507	return prv;
	508	}
	509
	510	static int
	511	key_perm_ok(int fd, const char *filename)
	512	{
	513	struct stat st;
	514
	515	if (fstat(fd, &st) < 0)
	516	return 0;
	517	/*
	518	* if a key owned by the user is accessed, then we check the
	519	* permissions of the file. if the key owned by a different user,
	520	* then we don't care.
	521	*/
	522	#ifdef HAVE_CYGWIN
	523	if (check_ntsec(filename))
	524	#endif
	525	if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0) {
	526	error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
	527	error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @");
	528	error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
	529	error("Permissions 0%3.3o for '%s' are too open.",
0fff78ff	530	(u_int)st.st_mode & 0777, filename);
3c0ef626	531	error("It is recommended that your private key files are NOT accessible by others.");
	532	error("This private key will be ignored.");
	533	return 0;
	534	}
	535	return 1;
	536	}
	537
	538	Key *
	539	key_load_private_type(int type, const char filename, const char passphrase,
	540	char **commentp)
	541	{
	542	int fd;
	543
	544	fd = open(filename, O_RDONLY);
	545	if (fd < 0)
	546	return NULL;
	547	if (!key_perm_ok(fd, filename)) {
	548	error("bad permissions: ignore key: %s", filename);
	549	close(fd);
	550	return NULL;
	551	}
	552	switch (type) {
	553	case KEY_RSA1:
	554	return key_load_private_rsa1(fd, filename, passphrase,
	555	commentp);
	556	/* closes fd */
	557	break;
	558	case KEY_DSA:
	559	case KEY_RSA:
	560	case KEY_UNSPEC:
	561	return key_load_private_pem(fd, type, passphrase, commentp);
	562	/* closes fd */
	563	break;
	564	default:
	565	close(fd);
	566	break;
	567	}
	568	return NULL;
	569	}
	570
	571	Key *
	572	key_load_private(const char filename, const char passphrase,
	573	char **commentp)
	574	{
	575	Key pub, prv;
	576	int fd;
	577
	578	fd = open(filename, O_RDONLY);
	579	if (fd < 0)
	580	return NULL;
	581	if (!key_perm_ok(fd, filename)) {
	582	error("bad permissions: ignore key: %s", filename);
	583	close(fd);
	584	return NULL;
	585	}
	586	pub = key_load_public_rsa1(fd, filename, commentp);
	587	lseek(fd, (off_t) 0, SEEK_SET); /* rewind */
	588	if (pub == NULL) {
	589	/* closes fd */
	590	prv = key_load_private_pem(fd, KEY_UNSPEC, passphrase, NULL);
	591	/* use the filename as a comment for PEM */
	592	if (commentp && prv)
	593	*commentp = xstrdup(filename);
	594	} else {
595	/* it's a SSH v1 key if the public key part is readable */
596	key_free(pub);
597	/* closes fd */
598	prv = key_load_private_rsa1(fd, filename, passphrase, NULL);
599	}
600	return prv;
601	}
602
603	static int
604	key_try_load_public(Key k, const char filename, char **commentp)
605	{
606	FILE *f;
996d5e62	607	char line[SSH_MAX_PUBKEY_BYTES];
3c0ef626	608	char *cp;
996d5e62	609	u_long linenum = 0;
3c0ef626	610
	611	f = fopen(filename, "r");
	612	if (f != NULL) {
996d5e62	613	while (read_keyfile_line(f, filename, line, sizeof(line),
996d5e62	614	&linenum) != -1) {
3c0ef626	615	cp = line;
e9a17296	616	switch (*cp) {
3c0ef626	617	case '#':
	618	case '\n':
	619	case '\0':
	620	continue;
	621	}
	622	/* Skip leading whitespace. */
	623	for (; cp && (cp == ' ' \|\| *cp == '\t'); cp++)
	624	;
	625	if (*cp) {
	626	if (key_read(k, &cp) == 1) {
	627	if (commentp)
	628	*commentp=xstrdup(filename);
	629	fclose(f);
	630	return 1;
	631	}
	632	}
	633	}
	634	fclose(f);
	635	}
	636	return 0;
	637	}
	638
	639	/* load public key from ssh v1 private or any pubkey file */
	640	Key *
	641	key_load_public(const char filename, char *commentp)
	642	{
	643	Key *pub;
	644	char file[MAXPATHLEN];
	645
0fff78ff	646	/* try rsa1 private key */
3c0ef626	647	pub = key_load_public_type(KEY_RSA1, filename, commentp);
	648	if (pub != NULL)
	649	return pub;
0fff78ff	650
	651	/* try rsa1 public key */
	652	pub = key_new(KEY_RSA1);
	653	if (key_try_load_public(pub, filename, commentp) == 1)
	654	return pub;
	655	key_free(pub);
	656
	657	/* try ssh2 public key */
3c0ef626	658	pub = key_new(KEY_UNSPEC);
	659	if (key_try_load_public(pub, filename, commentp) == 1)
	660	return pub;
	661	if ((strlcpy(file, filename, sizeof file) < sizeof(file)) &&
	662	(strlcat(file, ".pub", sizeof file) < sizeof(file)) &&
	663	(key_try_load_public(pub, file, commentp) == 1))
	664	return pub;
	665	key_free(pub);
	666	return NULL;
	667	}