~ubuntu-branches/ubuntu/lucid/openssh/lucid

/* $OpenBSD: authfile.c,v 1.76 2006/08/03 03:34:41 deraadt 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 <sys/param.h>

#include <sys/uio.h>

#include <openssl/err.h>

#include <openssl/evp.h>

#include <openssl/pem.h>

#include <errno.h>

#include <fcntl.h>

#include <stdarg.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include "xmalloc.h"

#include "cipher.h"

#include "buffer.h"

#include "key.h"

#include "ssh.h"

#include "log.h"

#include "authfile.h"

#include "rsa.h"

#include "misc.h"

#include "atomicio.h"

#include "pathnames.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;

}

/* Scan a blacklist of known-vulnerable keys in blacklist_file. */

static int

blacklisted_key_in_file(const Key *key, const char *blacklist_file, char **fp)

{

	int fd = -1;

	char *dgst_hex = NULL;

	char *dgst_packed = NULL, *p;

	int i;

	size_t line_len;

	struct stat st;

	char buf[256];

	off_t start, lower, upper;

	int ret = 0;

	debug("Checking blacklist file %s", blacklist_file);

	fd = open(blacklist_file, O_RDONLY);

	if (fd < 0) {

		ret = -1;

		goto out;

	}

	dgst_hex = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);

	/* Remove all colons */

	dgst_packed = xcalloc(1, strlen(dgst_hex) + 1);

	for (i = 0, p = dgst_packed; dgst_hex[i]; i++)

		if (dgst_hex[i] != ':')

			*p++ = dgst_hex[i];

	/* Only compare least-significant 80 bits (to keep the blacklist

	 * size down)

	 */

	line_len = strlen(dgst_packed + 12);

	if (line_len > 32)

		goto out;

	/* Skip leading comments */

	start = 0;

	for (;;) {

		ssize_t r;

		char *newline;

		r = atomicio(read, fd, buf, sizeof(buf));

		if (r <= 0)

			goto out;

		if (buf[0] != '#')

			break;

		newline = memchr(buf, '\n', sizeof(buf));

		if (!newline)

			goto out;

		start += newline + 1 - buf;

		if (lseek(fd, start, SEEK_SET) < 0)

			goto out;

	}

	/* Initialise binary search record numbers */

	if (fstat(fd, &st) < 0)

		goto out;