authfile.c - platform/external/openssh - Gitiles

 /*
  *
  * authfile.c
  *
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  *
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
  *
  * Created: Mon Mar 27 03:52:05 1995 ylo
  *
  * This file contains functions for reading and writing identity files, and
  * for reading the passphrase from the user.
  *
  */

 #include "includes.h"
 RCSID("$Id: authfile.c,v 1.11 2000/04/16 02:31:49 damien Exp $");

 #include <openssl/bn.h>
 #include "xmalloc.h"
 #include "buffer.h"
 #include "bufaux.h"
 #include "cipher.h"
 #include "ssh.h"

 /* Version identification string for identity files. */
 #define 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.
  */

 int
 save_private_key(const char *filename, const char *passphrase,
 		 RSA *key, const char *comment)
 {
 	Buffer buffer, encrypted;
 	char buf[100], *cp;
 	int fd, i;
 	CipherContext cipher;
 	int cipher_type;
 	u_int32_t rand;

 	/*
 	 * If the passphrase is empty, use SSH_CIPHER_NONE to ease converting
 	 * to another cipher; otherwise use SSH_AUTHFILE_CIPHER.
 	 */
 	if (strcmp(passphrase, "") == 0)
 		cipher_type = SSH_CIPHER_NONE;
 	else
 		cipher_type = SSH_AUTHFILE_CIPHER;

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

 	/* Put checkbytes for checking passphrase validity. */
 	rand = arc4random();
 	buf[0] = rand & 0xff;
 	buf[1] = (rand >> 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->d);
 	buffer_put_bignum(&buffer, key->iqmp);
 	buffer_put_bignum(&buffer, key->q);	/* reverse from SSL p */
 	buffer_put_bignum(&buffer, key->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. */
 	cp = AUTHFILE_ID_STRING;
 	for (i = 0; cp[i]; i++)
 		buffer_put_char(&encrypted, cp[i]);
 	buffer_put_char(&encrypted, 0);

 	/* Store cipher type. */
 	buffer_put_char(&encrypted, cipher_type);
 	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->n));
 	buffer_put_bignum(&encrypted, key->n);
 	buffer_put_bignum(&encrypted, key->e);
 	buffer_put_string(&encrypted, comment, strlen(comment));

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

 	cipher_set_key_string(&cipher, cipher_type, passphrase);
 	cipher_encrypt(&cipher, (unsigned char *) cp,
 		       (unsigned char *) buffer_ptr(&buffer),
 		       buffer_len(&buffer));
 	memset(&cipher, 0, sizeof(cipher));

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

 	fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600);
 	if (fd < 0)
 		return 0;
 	if (write(fd, buffer_ptr(&encrypted), buffer_len(&encrypted)) !=
 	    buffer_len(&encrypted)) {
 		debug("Write to key file %.200s failed: %.100s", filename,
 		      strerror(errno));
 		buffer_free(&encrypted);
 		close(fd);
 		remove(filename);
 		return 0;
 	}
 	close(fd);
 	buffer_free(&encrypted);
 	return 1;
 }

 /*
  * Loads the public part of the key file.  Returns 0 if an error was
  * encountered (the file does not exist or is not readable), and non-zero
  * otherwise.
  */

 int
 load_public_key(const char *filename, RSA * pub,
 		char **comment_return)
 {
 	int fd, i;
 	off_t len;
 	Buffer buffer;
 	char *cp;

 	fd = open(filename, O_RDONLY);
 	if (fd < 0)
 		return 0;
 	len = lseek(fd, (off_t) 0, SEEK_END);
 	lseek(fd, (off_t) 0, SEEK_SET);

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

 	if (read(fd, cp, (size_t) len) != (size_t) len) {
 		debug("Read from key file %.200s failed: %.100s", filename,
 		      strerror(errno));
 		buffer_free(&buffer);
 		close(fd);
 		return 0;
 	}
 	close(fd);

 	/* Check that it is at least big enought to contain the ID string. */
 	if (len < strlen(AUTHFILE_ID_STRING) + 1) {
 		debug("Bad key file %.200s.", filename);
 		buffer_free(&buffer);
 		return 0;
 	}
 	/*
 	 * Make sure it begins with the id string.  Consume the id string
 	 * from the buffer.
 	 */
 	for (i = 0; i < (unsigned int) strlen(AUTHFILE_ID_STRING) + 1; i++)
 		if (buffer_get_char(&buffer) != (u_char) AUTHFILE_ID_STRING[i]) {
 			debug("Bad key file %.200s.", filename);
 			buffer_free(&buffer);
 			return 0;
 		}
 	/* 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. */
 	buffer_get_int(&buffer);
 	pub->n = BN_new();
 	buffer_get_bignum(&buffer, pub->n);
 	pub->e = BN_new();
 	buffer_get_bignum(&buffer, pub->e);
 	if (comment_return)
 		*comment_return = buffer_get_string(&buffer, NULL);
 	/* The encrypted private part is not parsed by this function. */

 	buffer_free(&buffer);

 	return 1;
 }

 /*
  * 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.
  */

 int
 load_private_key(const char *filename, const char *passphrase,
 		 RSA * prv, char **comment_return)
 {
 	int fd, i, check1, check2, cipher_type;
 	off_t len;
 	Buffer buffer, decrypted;
 	char *cp;
 	CipherContext cipher;
 	BN_CTX *ctx;
 	BIGNUM *aux;
 	struct stat st;

 	fd = open(filename, O_RDONLY);
 	if (fd < 0)
 		return 0;

 	/* check owner and modes */
 	if (fstat(fd, &st) < 0 ||
 	    (st.st_uid != 0 && getuid() != 0 && st.st_uid != getuid()) ||
 	    (st.st_mode & 077) != 0) {
 		close(fd);
 		error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
 		error("@         WARNING: UNPROTECTED PRIVATE KEY FILE!          @");
 		error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
 		error("Bad ownership or mode(0%3.3o) for '%s'.",
 		      st.st_mode & 0777, filename);
 		error("It is recommended that your private key files are NOT accessible by others.");
 		return 0;
 	}
 	len = lseek(fd, (off_t) 0, SEEK_END);
 	lseek(fd, (off_t) 0, SEEK_SET);

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

 	if (read(fd, cp, (size_t) len) != (size_t) len) {
 		debug("Read from key file %.200s failed: %.100s", filename,
 		      strerror(errno));
 		buffer_free(&buffer);
 		close(fd);
 		return 0;
 	}
 	close(fd);

 	/* Check that it is at least big enought to contain the ID string. */
 	if (len < strlen(AUTHFILE_ID_STRING) + 1) {
 		debug("Bad key file %.200s.", filename);
 		buffer_free(&buffer);
 		return 0;
 	}
 	/*
 	 * Make sure it begins with the id string.  Consume the id string
 	 * from the buffer.
 	 */
 	for (i = 0; i < (unsigned int) strlen(AUTHFILE_ID_STRING) + 1; i++)
 		if (buffer_get_char(&buffer) != (unsigned char) AUTHFILE_ID_STRING[i]) {
 			debug("Bad key file %.200s.", filename);
 			buffer_free(&buffer);
 			return 0;
 		}
 	/* Read cipher type. */
 	cipher_type = buffer_get_char(&buffer);
 	(void) buffer_get_int(&buffer);	/* Reserved data. */

 	/* Read the public key from the buffer. */
 	buffer_get_int(&buffer);
 	prv->n = BN_new();
 	buffer_get_bignum(&buffer, prv->n);
 	prv->e = BN_new();
 	buffer_get_bignum(&buffer, prv->e);
 	if (comment_return)
 		*comment_return = buffer_get_string(&buffer, NULL);
 	else
 		xfree(buffer_get_string(&buffer, NULL));

 	/* Check that it is a supported cipher. */
 	if (((cipher_mask1() | SSH_CIPHER_NONE | SSH_AUTHFILE_CIPHER) &
 	     (1 << cipher_type)) == 0) {
 		debug("Unsupported cipher %.100s used in key file %.200s.",
 		      cipher_name(cipher_type), filename);
 		buffer_free(&buffer);
 		goto fail;
 	}
 	/* Initialize space for decrypted data. */
 	buffer_init(&decrypted);
 	buffer_append_space(&decrypted, &cp, buffer_len(&buffer));

 	/* Rest of the buffer is encrypted.  Decrypt it using the passphrase. */
 	cipher_set_key_string(&cipher, cipher_type, passphrase);
 	cipher_decrypt(&cipher, (unsigned char *) cp,
 		       (unsigned char *) buffer_ptr(&buffer),
 		       buffer_len(&buffer));

 	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);
 fail:
 		BN_clear_free(prv->n);
 		BN_clear_free(prv->e);
 		if (comment_return)
 			xfree(*comment_return);
 		return 0;
 	}
 	/* Read the rest of the private key. */
 	prv->d = BN_new();
 	buffer_get_bignum(&decrypted, prv->d);
 	prv->iqmp = BN_new();
 	buffer_get_bignum(&decrypted, prv->iqmp);	/* u */
 	/* in SSL and SSH p and q are exchanged */
 	prv->q = BN_new();
 	buffer_get_bignum(&decrypted, prv->q);		/* p */
 	prv->p = BN_new();
 	buffer_get_bignum(&decrypted, prv->p);		/* q */

 	ctx = BN_CTX_new();
 	aux = BN_new();

 	BN_sub(aux, prv->q, BN_value_one());
 	prv->dmq1 = BN_new();
 	BN_mod(prv->dmq1, prv->d, aux, ctx);

 	BN_sub(aux, prv->p, BN_value_one());
 	prv->dmp1 = BN_new();
 	BN_mod(prv->dmp1, prv->d, aux, ctx);

 	BN_clear_free(aux);
 	BN_CTX_free(ctx);

 	buffer_free(&decrypted);

 	return 1;
 }
	/*
	*
	* authfile.c
	*
	* Author: Tatu Ylonen <ylo@cs.hut.fi>
	*
	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	* All rights reserved
	*
	* Created: Mon Mar 27 03:52:05 1995 ylo
	*
	* This file contains functions for reading and writing identity files, and
	* for reading the passphrase from the user.
	*
	*/

	#include "includes.h"
	RCSID("$Id: authfile.c,v 1.11 2000/04/16 02:31:49 damien Exp $");

	#include <openssl/bn.h>
	#include "xmalloc.h"
	#include "buffer.h"
	#include "bufaux.h"
	#include "cipher.h"
	#include "ssh.h"

	/* Version identification string for identity files. */
	#define 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.
	*/

	int
	save_private_key(const char filename, const char passphrase,
	RSA key, const char comment)
	{
	Buffer buffer, encrypted;
	char buf[100], *cp;
	int fd, i;
	CipherContext cipher;
	int cipher_type;
	u_int32_t rand;

	/*
	* If the passphrase is empty, use SSH_CIPHER_NONE to ease converting
	* to another cipher; otherwise use SSH_AUTHFILE_CIPHER.
	*/
	if (strcmp(passphrase, "") == 0)
	cipher_type = SSH_CIPHER_NONE;
	else
	cipher_type = SSH_AUTHFILE_CIPHER;

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

	/* Put checkbytes for checking passphrase validity. */
	rand = arc4random();
	buf[0] = rand & 0xff;
	buf[1] = (rand >> 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->d);
	buffer_put_bignum(&buffer, key->iqmp);
	buffer_put_bignum(&buffer, key->q); /* reverse from SSL p */
	buffer_put_bignum(&buffer, key->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. */
	cp = AUTHFILE_ID_STRING;
	for (i = 0; cp[i]; i++)
	buffer_put_char(&encrypted, cp[i]);
	buffer_put_char(&encrypted, 0);

	/* Store cipher type. */
	buffer_put_char(&encrypted, cipher_type);
	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->n));
	buffer_put_bignum(&encrypted, key->n);
	buffer_put_bignum(&encrypted, key->e);
	buffer_put_string(&encrypted, comment, strlen(comment));

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

	cipher_set_key_string(&cipher, cipher_type, passphrase);
	cipher_encrypt(&cipher, (unsigned char *) cp,
	(unsigned char *) buffer_ptr(&buffer),
	buffer_len(&buffer));
	memset(&cipher, 0, sizeof(cipher));

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

	fd = open(filename, O_WRONLY \| O_CREAT \| O_TRUNC, 0600);
	if (fd < 0)
	return 0;
	if (write(fd, buffer_ptr(&encrypted), buffer_len(&encrypted)) !=
	buffer_len(&encrypted)) {
	debug("Write to key file %.200s failed: %.100s", filename,
	strerror(errno));
	buffer_free(&encrypted);
	close(fd);
	remove(filename);
	return 0;
	}
	close(fd);
	buffer_free(&encrypted);
	return 1;
	}

	/*
	* Loads the public part of the key file. Returns 0 if an error was
	* encountered (the file does not exist or is not readable), and non-zero
	* otherwise.
	*/

	int
	load_public_key(const char filename, RSA pub,
	char **comment_return)
	{
	int fd, i;
	off_t len;
	Buffer buffer;
	char *cp;

	fd = open(filename, O_RDONLY);
	if (fd < 0)
	return 0;
	len = lseek(fd, (off_t) 0, SEEK_END);
	lseek(fd, (off_t) 0, SEEK_SET);

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

	if (read(fd, cp, (size_t) len) != (size_t) len) {
	debug("Read from key file %.200s failed: %.100s", filename,
	strerror(errno));
	buffer_free(&buffer);
	close(fd);
	return 0;
	}
	close(fd);

	/* Check that it is at least big enought to contain the ID string. */
	if (len < strlen(AUTHFILE_ID_STRING) + 1) {
	debug("Bad key file %.200s.", filename);
	buffer_free(&buffer);
	return 0;
	}
	/*
	* Make sure it begins with the id string. Consume the id string
	* from the buffer.
	*/
	for (i = 0; i < (unsigned int) strlen(AUTHFILE_ID_STRING) + 1; i++)
	if (buffer_get_char(&buffer) != (u_char) AUTHFILE_ID_STRING[i]) {
	debug("Bad key file %.200s.", filename);
	buffer_free(&buffer);
	return 0;
	}
	/* 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. */
	buffer_get_int(&buffer);
	pub->n = BN_new();
	buffer_get_bignum(&buffer, pub->n);
	pub->e = BN_new();
	buffer_get_bignum(&buffer, pub->e);
	if (comment_return)
	*comment_return = buffer_get_string(&buffer, NULL);
	/* The encrypted private part is not parsed by this function. */

	buffer_free(&buffer);

	return 1;
	}

	/*
	* 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.
	*/

	int
	load_private_key(const char filename, const char passphrase,
	RSA * prv, char **comment_return)
	{
	int fd, i, check1, check2, cipher_type;
	off_t len;
	Buffer buffer, decrypted;
	char *cp;
	CipherContext cipher;
	BN_CTX *ctx;
	BIGNUM *aux;
	struct stat st;

	fd = open(filename, O_RDONLY);
	if (fd < 0)
	return 0;

	/* check owner and modes */
	if (fstat(fd, &st) < 0 \|\|
	(st.st_uid != 0 && getuid() != 0 && st.st_uid != getuid()) \|\|
	(st.st_mode & 077) != 0) {
	close(fd);
	error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
	error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @");
	error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
	error("Bad ownership or mode(0%3.3o) for '%s'.",
	st.st_mode & 0777, filename);
	error("It is recommended that your private key files are NOT accessible by others.");
	return 0;
	}
	len = lseek(fd, (off_t) 0, SEEK_END);
	lseek(fd, (off_t) 0, SEEK_SET);

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

	if (read(fd, cp, (size_t) len) != (size_t) len) {
	debug("Read from key file %.200s failed: %.100s", filename,
	strerror(errno));
	buffer_free(&buffer);
	close(fd);
	return 0;
	}
	close(fd);

	/* Check that it is at least big enought to contain the ID string. */
	if (len < strlen(AUTHFILE_ID_STRING) + 1) {
	debug("Bad key file %.200s.", filename);
	buffer_free(&buffer);
	return 0;
	}
	/*
	* Make sure it begins with the id string. Consume the id string
	* from the buffer.
	*/
	for (i = 0; i < (unsigned int) strlen(AUTHFILE_ID_STRING) + 1; i++)
	if (buffer_get_char(&buffer) != (unsigned char) AUTHFILE_ID_STRING[i]) {
	debug("Bad key file %.200s.", filename);
	buffer_free(&buffer);
	return 0;
	}
	/* Read cipher type. */
	cipher_type = buffer_get_char(&buffer);
	(void) buffer_get_int(&buffer); /* Reserved data. */

	/* Read the public key from the buffer. */
	buffer_get_int(&buffer);
	prv->n = BN_new();
	buffer_get_bignum(&buffer, prv->n);
	prv->e = BN_new();
	buffer_get_bignum(&buffer, prv->e);
	if (comment_return)
	*comment_return = buffer_get_string(&buffer, NULL);
	else
	xfree(buffer_get_string(&buffer, NULL));

	/* Check that it is a supported cipher. */
	if (((cipher_mask1() \| SSH_CIPHER_NONE \| SSH_AUTHFILE_CIPHER) &
	(1 << cipher_type)) == 0) {
	debug("Unsupported cipher %.100s used in key file %.200s.",
	cipher_name(cipher_type), filename);
	buffer_free(&buffer);
	goto fail;
	}
	/* Initialize space for decrypted data. */
	buffer_init(&decrypted);
	buffer_append_space(&decrypted, &cp, buffer_len(&buffer));

	/* Rest of the buffer is encrypted. Decrypt it using the passphrase. */
	cipher_set_key_string(&cipher, cipher_type, passphrase);
	cipher_decrypt(&cipher, (unsigned char *) cp,
	(unsigned char *) buffer_ptr(&buffer),
	buffer_len(&buffer));

	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);
	fail:
	BN_clear_free(prv->n);
	BN_clear_free(prv->e);
	if (comment_return)
	xfree(*comment_return);
	return 0;
	}
	/* Read the rest of the private key. */
	prv->d = BN_new();
	buffer_get_bignum(&decrypted, prv->d);
	prv->iqmp = BN_new();
	buffer_get_bignum(&decrypted, prv->iqmp); /* u */
	/* in SSL and SSH p and q are exchanged */
	prv->q = BN_new();
	buffer_get_bignum(&decrypted, prv->q); /* p */
	prv->p = BN_new();
	buffer_get_bignum(&decrypted, prv->p); /* q */

	ctx = BN_CTX_new();
	aux = BN_new();

	BN_sub(aux, prv->q, BN_value_one());
	prv->dmq1 = BN_new();
	BN_mod(prv->dmq1, prv->d, aux, ctx);

	BN_sub(aux, prv->p, BN_value_one());
	prv->dmp1 = BN_new();
	BN_mod(prv->dmp1, prv->d, aux, ctx);

	BN_clear_free(aux);
	BN_CTX_free(ctx);

	buffer_free(&decrypted);

	return 1;
	}