NetBSD/crypto/dist/ssh/authfile.c

605 lines
16 KiB
C

/* $NetBSD: authfile.c,v 1.1.1.2 2001/01/14 04:50:04 itojun 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.
*/
/* from OpenBSD: authfile.c,v 1.24 2000/12/20 19:26:56 markus Exp */
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: authfile.c,v 1.1.1.2 2001/01/14 04:50:04 itojun Exp $");
#endif
#include "includes.h"
#include <openssl/bn.h>
#include <openssl/dsa.h>
#include <openssl/rsa.h>
#include <openssl/err.h>
#include <openssl/pem.h>
#include <openssl/evp.h>
#include <openssl/rand.h>
#include "xmalloc.h"
#include "buffer.h"
#include "bufaux.h"
#include "ssh.h"
#include "key.h"
#include "authfile.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.
*/
static int
save_private_key_rsa1(const char *filename, const char *passphrase,
RSA *key, const char *comment)
{
Buffer buffer, encrypted;
char buf[100], *cp;
int fd, i;
CipherContext ciphercontext;
Cipher *cipher;
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 = cipher_by_number(SSH_CIPHER_NONE);
else
cipher = cipher_by_number(SSH_AUTHFILE_CIPHER);
if (cipher == 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. */
/* XXXthorpej */
RAND_pseudo_bytes((u_char *)&rand, sizeof(rand));
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->number);
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(&ciphercontext, cipher, passphrase);
cipher_encrypt(&ciphercontext, (u_char *) cp,
(u_char *) buffer_ptr(&buffer), buffer_len(&buffer));
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)
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);
unlink(filename);
return 0;
}
close(fd);
buffer_free(&encrypted);
return 1;
}
/* save SSH2 key in OpenSSL PEM format */
static int
save_private_key_ssh2(const char *filename, const char *_passphrase,
Key *key, const char *comment)
{
FILE *fp;
int fd;
int success = 0;
int len = strlen(_passphrase);
char *passphrase = (len > 0) ? (char *)_passphrase : NULL;
EVP_CIPHER *cipher = (len > 0) ? EVP_des_ede3_cbc() : NULL;
if (len > 0 && len <= 4) {
error("passphrase too short: %d bytes", len);
errno = 0;
return 0;
}
fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600);
if (fd < 0) {
debug("open %s failed", filename);
return 0;
}
fp = fdopen(fd, "w");
if (fp == NULL ) {
debug("fdopen %s failed", filename);
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
save_private_key(const char *filename, const char *passphrase, Key *key,
const char *comment)
{
switch (key->type) {
case KEY_RSA1:
return save_private_key_rsa1(filename, passphrase, key->rsa, comment);
break;
case KEY_DSA:
case KEY_RSA:
return save_private_key_ssh2(filename, passphrase, key, comment);
break;
default:
break;
}
return 0;
}
/*
* 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.
*/
static int
load_public_key_rsa(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) {
debug3("Bad RSA1 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 < (u_int) strlen(AUTHFILE_ID_STRING) + 1; i++)
if (buffer_get_char(&buffer) != (u_char) AUTHFILE_ID_STRING[i]) {
debug3("Bad RSA1 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);
/* XXX alloc */
if (pub->n == NULL)
pub->n = BN_new();
buffer_get_bignum(&buffer, pub->n);
/* XXX alloc */
if (pub->e == NULL)
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;
}
/* load public key from private-key file */
int
load_public_key(const char *filename, Key * key, char **comment_return)
{
switch (key->type) {
case KEY_RSA1:
return load_public_key_rsa(filename, key->rsa, comment_return);
break;
case KEY_DSA:
case KEY_RSA:
default:
break;
}
return 0;
}
/*
* 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 int
load_private_key_rsa1(int fd, const char *filename,
const char *passphrase, RSA * prv, char **comment_return)
{
int i, check1, check2, cipher_type;
off_t len;
Buffer buffer, decrypted;
char *cp;
CipherContext ciphercontext;
Cipher *cipher;
BN_CTX *ctx;
BIGNUM *aux;
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) {
debug3("Bad RSA1 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 < (u_int) strlen(AUTHFILE_ID_STRING) + 1; i++)
if (buffer_get_char(&buffer) != (u_char) AUTHFILE_ID_STRING[i]) {
debug3("Bad RSA1 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. */
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);
buffer_append_space(&decrypted, &cp, buffer_len(&buffer));
/* Rest of the buffer is encrypted. Decrypt it using the passphrase. */
cipher_set_key_string(&ciphercontext, cipher, passphrase);
cipher_decrypt(&ciphercontext, (u_char *) cp,
(u_char *) buffer_ptr(&buffer), buffer_len(&buffer));
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);
fail:
BN_clear_free(prv->n);
prv->n = NULL;
BN_clear_free(prv->e);
prv->e = NULL;
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;
}
static int
load_private_key_ssh2(int fd, const char *passphrase, Key *k, char **comment_return)
{
FILE *fp;
int success = 0;
EVP_PKEY *pk = NULL;
char *name = "<no key>";
fp = fdopen(fd, "r");
if (fp == NULL) {
error("fdopen failed");
return 0;
}
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) {
/* replace k->rsa with loaded key */
if (k->type == KEY_RSA || k->type == KEY_UNSPEC) {
if (k->rsa != NULL)
RSA_free(k->rsa);
k->rsa = EVP_PKEY_get1_RSA(pk);
k->type = KEY_RSA;
name = "rsa w/o comment";
success = 1;
#ifdef DEBUG_PK
RSA_print_fp(stderr, k->rsa, 8);
#endif
}
} else if (pk->type == EVP_PKEY_DSA) {
/* replace k->dsa with loaded key */
if (k->type == KEY_DSA || k->type == KEY_UNSPEC) {
if (k->dsa != NULL)
DSA_free(k->dsa);
k->dsa = EVP_PKEY_get1_DSA(pk);
k->type = KEY_DSA;
name = "dsa w/o comment";
#ifdef DEBUG_PK
DSA_print_fp(stderr, k->dsa, 8);
#endif
success = 1;
}
} 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 (success && comment_return)
*comment_return = xstrdup(name);
debug("read SSH2 private key done: name %s success %d", name, success);
return success;
}
int
load_private_key(const char *filename, const char *passphrase, Key *key,
char **comment_return)
{
int fd;
int ret = 0;
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;
}
switch (key->type) {
case KEY_RSA1:
if (key->rsa->e != NULL) {
BN_clear_free(key->rsa->e);
key->rsa->e = NULL;
}
if (key->rsa->n != NULL) {
BN_clear_free(key->rsa->n);
key->rsa->n = NULL;
}
ret = load_private_key_rsa1(fd, filename, passphrase,
key->rsa, comment_return);
break;
case KEY_DSA:
case KEY_RSA:
case KEY_UNSPEC:
ret = load_private_key_ssh2(fd, passphrase, key, comment_return);
default:
break;
}
close(fd);
return ret;
}
static int
do_load_public_key(const char *filename, Key *k, char **commentp)
{
FILE *f;
char line[1024];
char *cp;
f = fopen(filename, "r");
if (f != NULL) {
while (fgets(line, sizeof(line), f)) {
line[sizeof(line)-1] = '\0';
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 pubkey file */
int
try_load_public_key(const char *filename, Key *k, char **commentp)
{
char pub[MAXPATHLEN];
if (do_load_public_key(filename, k, commentp) == 1)
return 1;
if (strlcpy(pub, filename, sizeof pub) >= MAXPATHLEN)
return 0;
if (strlcat(pub, ".pub", sizeof pub) >= MAXPATHLEN)
return 0;
if (do_load_public_key(pub, k, commentp) == 1)
return 1;
return 0;
}