File: [local] / src / usr.bin / ssh / authfile.c (download)
Revision 1.101, Sun Dec 29 04:35:50 2013 UTC (10 years, 5 months ago) by djm
Branch: MAIN
Changes since 1.100: +2 -1 lines
don't refuse to load Ed25519 certificates
|
/* $OpenBSD: authfile.c,v 1.101 2013/12/29 04:35:50 djm 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, 2013 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 <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 "crypto_api.h"
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <util.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 "uuencode.h"
/* openssh private key file format */
#define MARK_BEGIN "-----BEGIN OPENSSH PRIVATE KEY-----\n"
#define MARK_END "-----END OPENSSH PRIVATE KEY-----\n"
#define KDFNAME "bcrypt"
#define AUTH_MAGIC "openssh-key-v1"
#define SALT_LEN 16
#define DEFAULT_CIPHERNAME "aes256-cbc"
#define DEFAULT_ROUNDS 16
#define MAX_KEY_FILE_SIZE (1024 * 1024)
/* Version identification string for SSH v1 identity files. */
static const char authfile_id_string[] =
"SSH PRIVATE KEY FILE FORMAT 1.1\n";
static int
key_private_to_blob2(Key *prv, Buffer *blob, const char *passphrase,
const char *comment, const char *ciphername, int rounds)
{
u_char *key, *cp, salt[SALT_LEN];
size_t keylen, ivlen, blocksize, authlen;
u_int len, check;
int i, n;
const Cipher *c;
Buffer encoded, b, kdf;
CipherContext ctx;
const char *kdfname = KDFNAME;
if (rounds <= 0)
rounds = DEFAULT_ROUNDS;
if (passphrase == NULL || !strlen(passphrase)) {
ciphername = "none";
kdfname = "none";
} else if (ciphername == NULL)
ciphername = DEFAULT_CIPHERNAME;
else if (cipher_number(ciphername) != SSH_CIPHER_SSH2)
fatal("invalid cipher");
if ((c = cipher_by_name(ciphername)) == NULL)
fatal("unknown cipher name");
buffer_init(&kdf);
blocksize = cipher_blocksize(c);
keylen = cipher_keylen(c);
ivlen = cipher_ivlen(c);
authlen = cipher_authlen(c);
key = xcalloc(1, keylen + ivlen);
if (strcmp(kdfname, "none") != 0) {
arc4random_buf(salt, SALT_LEN);
if (bcrypt_pbkdf(passphrase, strlen(passphrase),
salt, SALT_LEN, key, keylen + ivlen, rounds) < 0)
fatal("bcrypt_pbkdf failed");
buffer_put_string(&kdf, salt, SALT_LEN);
buffer_put_int(&kdf, rounds);
}
cipher_init(&ctx, c, key, keylen, key + keylen , ivlen, 1);
memset(key, 0, keylen + ivlen);
free(key);
buffer_init(&encoded);
buffer_append(&encoded, AUTH_MAGIC, sizeof(AUTH_MAGIC));
buffer_put_cstring(&encoded, ciphername);
buffer_put_cstring(&encoded, kdfname);
buffer_put_string(&encoded, buffer_ptr(&kdf), buffer_len(&kdf));
buffer_put_int(&encoded, 1); /* number of keys */
key_to_blob(prv, &cp, &len); /* public key */
buffer_put_string(&encoded, cp, len);
memset(cp, 0, len);
free(cp);
buffer_free(&kdf);
/* set up the buffer that will be encrypted */
buffer_init(&b);
/* Random check bytes */
check = arc4random();
buffer_put_int(&b, check);
buffer_put_int(&b, check);
/* append private key and comment*/
key_private_serialize(prv, &b);
buffer_put_cstring(&b, comment);
/* padding */
i = 0;
while (buffer_len(&b) % blocksize)
buffer_put_char(&b, ++i & 0xff);
/* length */
buffer_put_int(&encoded, buffer_len(&b));
/* encrypt */
cp = buffer_append_space(&encoded, buffer_len(&b) + authlen);
if (cipher_crypt(&ctx, 0, cp, buffer_ptr(&b), buffer_len(&b), 0,
authlen) != 0)
fatal("%s: cipher_crypt failed", __func__);
buffer_free(&b);
cipher_cleanup(&ctx);
/* uuencode */
len = 2 * buffer_len(&encoded);
cp = xmalloc(len);
n = uuencode(buffer_ptr(&encoded), buffer_len(&encoded),
(char *)cp, len);
if (n < 0)
fatal("%s: uuencode", __func__);
buffer_clear(blob);
buffer_append(blob, MARK_BEGIN, sizeof(MARK_BEGIN) - 1);
for (i = 0; i < n; i++) {
buffer_put_char(blob, cp[i]);
if (i % 70 == 69)
buffer_put_char(blob, '\n');
}
if (i % 70 != 69)
buffer_put_char(blob, '\n');
buffer_append(blob, MARK_END, sizeof(MARK_END) - 1);
free(cp);
return buffer_len(blob);
}
static Key *
key_parse_private2(Buffer *blob, int type, const char *passphrase,
char **commentp)
{
u_char *key = NULL, *cp, *salt = NULL, pad, last;
char *comment = NULL, *ciphername = NULL, *kdfname = NULL, *kdfp;
u_int keylen = 0, ivlen, blocksize, slen, klen, len, rounds, nkeys;
u_int check1, check2, m1len, m2len;
size_t authlen;
const Cipher *c;
Buffer b, encoded, copy, kdf;
CipherContext ctx;
Key *k = NULL;
int dlen, ret, i;
buffer_init(&b);
buffer_init(&kdf);
buffer_init(&encoded);
buffer_init(©);
/* uudecode */
m1len = sizeof(MARK_BEGIN) - 1;
m2len = sizeof(MARK_END) - 1;
cp = buffer_ptr(blob);
len = buffer_len(blob);
if (len < m1len || memcmp(cp, MARK_BEGIN, m1len)) {
debug("%s: missing begin marker", __func__);
goto out;
}
cp += m1len;
len -= m1len;
while (len) {
if (*cp != '\n' && *cp != '\r')
buffer_put_char(&encoded, *cp);
last = *cp;
len--;
cp++;
if (last == '\n') {
if (len >= m2len && !memcmp(cp, MARK_END, m2len)) {
buffer_put_char(&encoded, '\0');
break;
}
}
}
if (!len) {
debug("%s: no end marker", __func__);
goto out;
}
len = buffer_len(&encoded);
if ((cp = buffer_append_space(©, len)) == NULL) {
error("%s: buffer_append_space", __func__);
goto out;
}
if ((dlen = uudecode(buffer_ptr(&encoded), cp, len)) < 0) {
error("%s: uudecode failed", __func__);
goto out;
}
if ((u_int)dlen > len) {
error("%s: crazy uudecode length %d > %u", __func__, dlen, len);
goto out;
}
buffer_consume_end(©, len - dlen);
if (buffer_len(©) < sizeof(AUTH_MAGIC) ||
memcmp(buffer_ptr(©), AUTH_MAGIC, sizeof(AUTH_MAGIC))) {
error("%s: bad magic", __func__);
goto out;
}
buffer_consume(©, sizeof(AUTH_MAGIC));
ciphername = buffer_get_cstring_ret(©, NULL);
if (ciphername == NULL ||
(c = cipher_by_name(ciphername)) == NULL) {
error("%s: unknown cipher name", __func__);
goto out;
}
if ((passphrase == NULL || !strlen(passphrase)) &&
strcmp(ciphername, "none") != 0) {
/* passphrase required */
goto out;
}
kdfname = buffer_get_cstring_ret(©, NULL);
if (kdfname == NULL ||
(!strcmp(kdfname, "none") && !strcmp(kdfname, "bcrypt"))) {
error("%s: unknown kdf name", __func__);
goto out;
}
if (!strcmp(kdfname, "none") && strcmp(ciphername, "none") != 0) {
error("%s: cipher %s requires kdf", __func__, ciphername);
goto out;
}
/* kdf options */
kdfp = buffer_get_string_ptr_ret(©, &klen);
if (kdfp == NULL) {
error("%s: kdf options not set", __func__);
goto out;
}
if (klen > 0) {
if ((cp = buffer_append_space(&kdf, klen)) == NULL) {
error("%s: kdf alloc failed", __func__);
goto out;
}
memcpy(cp, kdfp, klen);
}
/* number of keys */
if (buffer_get_int_ret(&nkeys, ©) < 0) {
error("%s: key counter missing", __func__);
goto out;
}
if (nkeys != 1) {
error("%s: only one key supported", __func__);
goto out;
}
/* pubkey */
if ((cp = buffer_get_string_ret(©, &len)) == NULL) {
error("%s: pubkey not found", __func__);
goto out;
}
free(cp); /* XXX check pubkey against decrypted private key */
/* size of encrypted key blob */
len = buffer_get_int(©);
blocksize = cipher_blocksize(c);
authlen = cipher_authlen(c);
if (len < blocksize) {
error("%s: encrypted data too small", __func__);
goto out;
}
if (len % blocksize) {
error("%s: length not multiple of blocksize", __func__);
goto out;
}
/* setup key */
keylen = cipher_keylen(c);
ivlen = cipher_ivlen(c);
key = xcalloc(1, keylen + ivlen);
if (!strcmp(kdfname, "bcrypt")) {
if ((salt = buffer_get_string_ret(&kdf, &slen)) == NULL) {
error("%s: salt not set", __func__);
goto out;
}
if (buffer_get_int_ret(&rounds, &kdf) < 0) {
error("%s: rounds not set", __func__);
goto out;
}
if (bcrypt_pbkdf(passphrase, strlen(passphrase), salt, slen,
key, keylen + ivlen, rounds) < 0) {
error("%s: bcrypt_pbkdf failed", __func__);
goto out;
}
}
cp = buffer_append_space(&b, len);
cipher_init(&ctx, c, key, keylen, key + keylen, ivlen, 0);
ret = cipher_crypt(&ctx, 0, cp, buffer_ptr(©), len, 0, authlen);
cipher_cleanup(&ctx);
buffer_consume(©, len);
/* fail silently on decryption errors */
if (ret != 0) {
debug("%s: decrypt failed", __func__);
goto out;
}
if (buffer_len(©) != 0) {
error("%s: key blob has trailing data (len = %u)", __func__,
buffer_len(©));
goto out;
}
/* check bytes */
if (buffer_get_int_ret(&check1, &b) < 0 ||
buffer_get_int_ret(&check2, &b) < 0) {
error("check bytes missing");
goto out;
}
if (check1 != check2) {
debug("%s: decrypt failed: 0x%08x != 0x%08x", __func__,
check1, check2);
goto out;
}
k = key_private_deserialize(&b);
/* comment */
comment = buffer_get_cstring_ret(&b, NULL);
i = 0;
while (buffer_len(&b)) {
if (buffer_get_char_ret(&pad, &b) == -1 ||
pad != (++i & 0xff)) {
error("%s: bad padding", __func__);
key_free(k);
k = NULL;
goto out;
}
}
if (k && commentp) {
*commentp = comment;
comment = NULL;
}
/* XXX decode pubkey and check against private */
out:
free(ciphername);
free(kdfname);
free(salt);
free(comment);
if (key)
memset(key, 0, keylen + ivlen);
free(key);
buffer_free(&encoded);
buffer_free(©);
buffer_free(&kdf);
buffer_free(&b);
return k;
}
/*
* Serialises the authentication (private) key to a blob, encrypting it with
* passphrase. The identification of the blob (lowest 64 bits of n) will
* precede the key to provide identification of the key without needing a
* passphrase.
*/
static int
key_private_rsa1_to_blob(Key *key, Buffer *blob, const char *passphrase,
const char *comment)
{
Buffer buffer, encrypted;
u_char buf[100], *cp;
int i, cipher_num;
CipherContext ciphercontext;
const 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);
if (cipher_crypt(&ciphercontext, 0, cp,
buffer_ptr(&buffer), buffer_len(&buffer), 0, 0) != 0)
fatal("%s: cipher_crypt failed", __func__);
cipher_cleanup(&ciphercontext);
memset(&ciphercontext, 0, sizeof(ciphercontext));
/* Destroy temporary data. */
memset(buf, 0, sizeof(buf));
buffer_free(&buffer);
buffer_append(blob, buffer_ptr(&encrypted), buffer_len(&encrypted));
buffer_free(&encrypted);
return 1;
}
/* convert SSH v2 key in OpenSSL PEM format */
static int
key_private_pem_to_blob(Key *key, Buffer *blob, const char *_passphrase,
const char *comment)
{
int success = 0;
int blen, len = strlen(_passphrase);
u_char *passphrase = (len > 0) ? (u_char *)_passphrase : NULL;
const EVP_CIPHER *cipher = (len > 0) ? EVP_aes_128_cbc() : NULL;
const u_char *bptr;
BIO *bio;
if (len > 0 && len <= 4) {
error("passphrase too short: have %d bytes, need > 4", len);
return 0;
}
if ((bio = BIO_new(BIO_s_mem())) == NULL) {
error("%s: BIO_new failed", __func__);
return 0;
}
switch (key->type) {
case KEY_DSA:
success = PEM_write_bio_DSAPrivateKey(bio, key->dsa,
cipher, passphrase, len, NULL, NULL);
break;
case KEY_ECDSA:
success = PEM_write_bio_ECPrivateKey(bio, key->ecdsa,
cipher, passphrase, len, NULL, NULL);
break;
case KEY_RSA:
success = PEM_write_bio_RSAPrivateKey(bio, key->rsa,
cipher, passphrase, len, NULL, NULL);
break;
}
if (success) {
if ((blen = BIO_get_mem_data(bio, &bptr)) <= 0)
success = 0;
else
buffer_append(blob, bptr, blen);
}
BIO_free(bio);
return success;
}
/* Save a key blob to a file */
static int
key_save_private_blob(Buffer *keybuf, const char *filename)
{
int fd;
if ((fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600)) < 0) {
error("open %s failed: %s.", filename, strerror(errno));
return 0;
}
if (atomicio(vwrite, fd, buffer_ptr(keybuf),
buffer_len(keybuf)) != buffer_len(keybuf)) {
error("write to key file %s failed: %s", filename,
strerror(errno));
close(fd);
unlink(filename);
return 0;
}
close(fd);
return 1;
}
/* Serialise "key" to buffer "blob" */
static int
key_private_to_blob(Key *key, Buffer *blob, const char *passphrase,
const char *comment, int force_new_format, const char *new_format_cipher,
int new_format_rounds)
{
switch (key->type) {
case KEY_RSA1:
return key_private_rsa1_to_blob(key, blob, passphrase, comment);
case KEY_DSA:
case KEY_ECDSA:
case KEY_RSA:
if (force_new_format) {
return key_private_to_blob2(key, blob, passphrase,
comment, new_format_cipher, new_format_rounds);
}
return key_private_pem_to_blob(key, blob, passphrase, comment);
case KEY_ED25519:
return key_private_to_blob2(key, blob, passphrase,
comment, new_format_cipher, new_format_rounds);
default:
error("%s: cannot save key type %d", __func__, key->type);
return 0;
}
}
int
key_save_private(Key *key, const char *filename, const char *passphrase,
const char *comment, int force_new_format, const char *new_format_cipher,
int new_format_rounds)
{
Buffer keyblob;
int success = 0;
buffer_init(&keyblob);
if (!key_private_to_blob(key, &keyblob, passphrase, comment,
force_new_format, new_format_cipher, new_format_rounds))
goto out;
if (!key_save_private_blob(&keyblob, filename))
goto out;
success = 1;
out:
buffer_free(&keyblob);
return success;
}
/*
* Parse the public, unencrypted portion of a RSA1 key.
*/
static Key *
key_parse_public_rsa1(Buffer *blob, char **commentp)
{
Key *pub;
Buffer copy;
/* Check that it is at least big enough to contain the ID string. */
if (buffer_len(blob) < sizeof(authfile_id_string)) {
debug3("Truncated RSA1 identifier");
return NULL;
}
/*
* Make sure it begins with the id string. Consume the id string
* from the buffer.
*/
if (memcmp(buffer_ptr(blob), authfile_id_string,
sizeof(authfile_id_string)) != 0) {
debug3("Incorrect RSA1 identifier");
return NULL;
}
buffer_init(©);
buffer_append(©, buffer_ptr(blob), buffer_len(blob));
buffer_consume(©, sizeof(authfile_id_string));
/* Skip cipher type and reserved data. */
(void) buffer_get_char(©); /* cipher type */
(void) buffer_get_int(©); /* reserved */
/* Read the public key from the buffer. */
(void) buffer_get_int(©);
pub = key_new(KEY_RSA1);
buffer_get_bignum(©, pub->rsa->n);
buffer_get_bignum(©, pub->rsa->e);
if (commentp)
*commentp = buffer_get_string(©, NULL);
/* The encrypted private part is not parsed by this function. */
buffer_free(©);
return pub;
}
/* Load a key from a fd into a buffer */
int
key_load_file(int fd, const char *filename, Buffer *blob)
{
u_char buf[1024];
size_t len;
struct stat st;
if (fstat(fd, &st) < 0) {
error("%s: fstat of key file %.200s%sfailed: %.100s", __func__,
filename == NULL ? "" : filename,
filename == NULL ? "" : " ",
strerror(errno));
return 0;
}
if ((st.st_mode & (S_IFSOCK|S_IFCHR|S_IFIFO)) == 0 &&
st.st_size > MAX_KEY_FILE_SIZE) {
toobig:
error("%s: key file %.200s%stoo large", __func__,
filename == NULL ? "" : filename,
filename == NULL ? "" : " ");
return 0;
}
buffer_clear(blob);
for (;;) {
if ((len = atomicio(read, fd, buf, sizeof(buf))) == 0) {
if (errno == EPIPE)
break;
debug("%s: read from key file %.200s%sfailed: %.100s",
__func__, filename == NULL ? "" : filename,
filename == NULL ? "" : " ", strerror(errno));
buffer_clear(blob);
bzero(buf, sizeof(buf));
return 0;
}
buffer_append(blob, buf, len);
if (buffer_len(blob) > MAX_KEY_FILE_SIZE) {
buffer_clear(blob);
bzero(buf, sizeof(buf));
goto toobig;
}
}
bzero(buf, sizeof(buf));
if ((st.st_mode & (S_IFSOCK|S_IFCHR|S_IFIFO)) == 0 &&
st.st_size != buffer_len(blob)) {
debug("%s: key file %.200s%schanged size while reading",
__func__, filename == NULL ? "" : filename,
filename == NULL ? "" : " ");
buffer_clear(blob);
return 0;
}
return 1;
}
/*
* 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;
buffer_init(&buffer);
if (!key_load_file(fd, filename, &buffer)) {
buffer_free(&buffer);
return NULL;
}
pub = key_parse_public_rsa1(&buffer, commentp);
if (pub == NULL)
debug3("Could not load \"%s\" as a RSA1 public key", filename);
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;
}
static Key *
key_parse_private_rsa1(Buffer *blob, const char *passphrase, char **commentp)
{
int check1, check2, cipher_type;
Buffer decrypted;
u_char *cp;
CipherContext ciphercontext;
const Cipher *cipher;
Key *prv = NULL;
Buffer copy;
/* Check that it is at least big enough to contain the ID string. */
if (buffer_len(blob) < sizeof(authfile_id_string)) {
debug3("Truncated RSA1 identifier");
return NULL;
}
/*
* Make sure it begins with the id string. Consume the id string
* from the buffer.
*/
if (memcmp(buffer_ptr(blob), authfile_id_string,
sizeof(authfile_id_string)) != 0) {
debug3("Incorrect RSA1 identifier");
return NULL;
}
buffer_init(©);
buffer_append(©, buffer_ptr(blob), buffer_len(blob));
buffer_consume(©, sizeof(authfile_id_string));
/* Read cipher type. */
cipher_type = buffer_get_char(©);
(void) buffer_get_int(©); /* Reserved data. */
/* Read the public key from the buffer. */
(void) buffer_get_int(©);
prv = key_new_private(KEY_RSA1);
buffer_get_bignum(©, prv->rsa->n);
buffer_get_bignum(©, prv->rsa->e);
if (commentp)
*commentp = buffer_get_string(©, NULL);
else
(void)buffer_get_string_ptr(©, NULL);
/* Check that it is a supported cipher. */
cipher = cipher_by_number(cipher_type);
if (cipher == NULL) {
debug("Unsupported RSA1 cipher %d", cipher_type);
buffer_free(©);
goto fail;
}
/* Initialize space for decrypted data. */
buffer_init(&decrypted);
cp = buffer_append_space(&decrypted, buffer_len(©));
/* Rest of the buffer is encrypted. Decrypt it using the passphrase. */
cipher_set_key_string(&ciphercontext, cipher, passphrase,
CIPHER_DECRYPT);
if (cipher_crypt(&ciphercontext, 0, cp,
buffer_ptr(©), buffer_len(©), 0, 0) != 0)
fatal("%s: cipher_crypt failed", __func__);
cipher_cleanup(&ciphercontext);
memset(&ciphercontext, 0, sizeof(ciphercontext));
buffer_free(©);
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 RSA1 key");
/* 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("%s: RSA_blinding_on failed", __func__);
goto fail;
}
return prv;
fail:
if (commentp != NULL)
free(*commentp);
key_free(prv);
return NULL;
}
static Key *
key_parse_private_pem(Buffer *blob, int type, const char *passphrase,
char **commentp)
{
EVP_PKEY *pk = NULL;
Key *prv = NULL;
char *name = "<no key>";
BIO *bio;
if ((bio = BIO_new_mem_buf(buffer_ptr(blob),
buffer_len(blob))) == NULL) {
error("%s: BIO_new_mem_buf failed", __func__);
return NULL;
}
pk = PEM_read_bio_PrivateKey(bio, NULL, NULL, (char *)passphrase);
BIO_free(bio);
if (pk == NULL) {
debug("%s: PEM_read_PrivateKey failed", __func__);
(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("%s: RSA_blinding_on failed", __func__);
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 if (pk->type == EVP_PKEY_EC &&
(type == KEY_UNSPEC||type==KEY_ECDSA)) {
prv = key_new(KEY_UNSPEC);
prv->ecdsa = EVP_PKEY_get1_EC_KEY(pk);
prv->type = KEY_ECDSA;
if ((prv->ecdsa_nid = key_ecdsa_key_to_nid(prv->ecdsa)) == -1 ||
key_curve_nid_to_name(prv->ecdsa_nid) == NULL ||
key_ec_validate_public(EC_KEY_get0_group(prv->ecdsa),
EC_KEY_get0_public_key(prv->ecdsa)) != 0 ||
key_ec_validate_private(prv->ecdsa) != 0) {
error("%s: bad ECDSA key", __func__);
key_free(prv);
prv = NULL;
}
name = "ecdsa w/o comment";
#ifdef DEBUG_PK
if (prv != NULL && prv->ecdsa != NULL)
key_dump_ec_key(prv->ecdsa);
#endif
} else {
error("%s: PEM_read_PrivateKey: mismatch or "
"unknown EVP_PKEY save_type %d", __func__, pk->save_type);
}
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;
}
Key *
key_load_private_pem(int fd, int type, const char *passphrase,
char **commentp)
{
Buffer buffer;
Key *prv;
buffer_init(&buffer);
if (!key_load_file(fd, NULL, &buffer)) {
buffer_free(&buffer);
return NULL;
}
prv = key_parse_private_pem(&buffer, type, passphrase, commentp);
buffer_free(&buffer);
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.
*/
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;
}
static Key *
key_parse_private_type(Buffer *blob, int type, const char *passphrase,
char **commentp)
{
Key *k;
switch (type) {
case KEY_RSA1:
return key_parse_private_rsa1(blob, passphrase, commentp);
case KEY_DSA:
case KEY_ECDSA:
case KEY_RSA:
return key_parse_private_pem(blob, type, passphrase, commentp);
case KEY_ED25519:
return key_parse_private2(blob, type, passphrase, commentp);
case KEY_UNSPEC:
if ((k = key_parse_private2(blob, type, passphrase, commentp)))
return k;
return key_parse_private_pem(blob, type, passphrase, commentp);
default:
error("%s: cannot parse key type %d", __func__, type);
break;
}
return NULL;
}
Key *
key_load_private_type(int type, const char *filename, const char *passphrase,
char **commentp, int *perm_ok)
{
int fd;
Key *ret;
Buffer buffer;
fd = open(filename, O_RDONLY);
if (fd < 0) {
debug("could not open key file '%s': %s", filename,
strerror(errno));
if (perm_ok != NULL)
*perm_ok = 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;
buffer_init(&buffer);
if (!key_load_file(fd, filename, &buffer)) {
buffer_free(&buffer);
close(fd);
return NULL;
}
close(fd);
ret = key_parse_private_type(&buffer, type, passphrase, commentp);
buffer_free(&buffer);
return ret;
}
Key *
key_parse_private(Buffer *buffer, const char *filename,
const char *passphrase, char **commentp)
{
Key *pub, *prv;
/* it's a SSH v1 key if the public key part is readable */
pub = key_parse_public_rsa1(buffer, commentp);
if (pub == NULL) {
prv = key_parse_private_type(buffer, KEY_UNSPEC,
passphrase, NULL);
/* use the filename as a comment for PEM */
if (commentp && prv)
*commentp = xstrdup(filename);
} else {
key_free(pub);
/* key_parse_public_rsa1() has already loaded the comment */
prv = key_parse_private_type(buffer, KEY_RSA1, passphrase,
NULL);
}
return prv;
}
Key *
key_load_private(const char *filename, const char *passphrase,
char **commentp)
{
Key *prv;
Buffer buffer;
int fd;
fd = open(filename, O_RDONLY);
if (fd < 0) {
debug("could not open key file '%s': %s", filename,
strerror(errno));
return NULL;
}
if (!key_perm_ok(fd, filename)) {
error("bad permissions: ignore key: %s", filename);
close(fd);
return NULL;
}
buffer_init(&buffer);
if (!key_load_file(fd, filename, &buffer)) {
buffer_free(&buffer);
close(fd);
return NULL;
}
close(fd);
prv = key_parse_private(&buffer, filename, passphrase, commentp);
buffer_free(&buffer);
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;
}
/* Abort loading if this looks like a private key */
if (strncmp(cp, "-----BEGIN", 10) == 0)
break;
/* Skip leading whitespace. */
for (; *cp && (*cp == ' ' || *cp == '\t'); cp++)
;
if (*cp) {
if (key_read(k, &cp) == 1) {
cp[strcspn(cp, "\r\n")] = '\0';
if (commentp) {
*commentp = xstrdup(*cp ?
cp : 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;
}
/* Load the certificate associated with the named private key */
Key *
key_load_cert(const char *filename)
{
Key *pub;
char *file;
pub = key_new(KEY_UNSPEC);
xasprintf(&file, "%s-cert.pub", filename);
if (key_try_load_public(pub, file, NULL) == 1) {
free(file);
return pub;
}
free(file);
key_free(pub);
return NULL;
}
/* Load private key and certificate */
Key *
key_load_private_cert(int type, const char *filename, const char *passphrase,
int *perm_ok)
{
Key *key, *pub;
switch (type) {
case KEY_RSA:
case KEY_DSA:
case KEY_ECDSA:
case KEY_ED25519:
break;
default:
error("%s: unsupported key type", __func__);
return NULL;
}
if ((key = key_load_private_type(type, filename,
passphrase, NULL, perm_ok)) == NULL)
return NULL;
if ((pub = key_load_cert(filename)) == NULL) {
key_free(key);
return NULL;
}
/* Make sure the private key matches the certificate */
if (key_equal_public(key, pub) == 0) {
error("%s: certificate does not match private key %s",
__func__, filename);
} else if (key_to_certified(key, key_cert_is_legacy(pub)) != 0) {
error("%s: key_to_certified failed", __func__);
} else {
key_cert_copy(pub, key);
key_free(pub);
return key;
}
key_free(key);
key_free(pub);
return NULL;
}
/*
* Returns 1 if the specified "key" is listed in the file "filename",
* 0 if the key is not listed or -1 on error.
* If strict_type is set then the key type must match exactly,
* otherwise a comparison that ignores certficiate data is performed.
*/
int
key_in_file(Key *key, const char *filename, int strict_type)
{
FILE *f;
char line[SSH_MAX_PUBKEY_BYTES];
char *cp;
u_long linenum = 0;
int ret = 0;
Key *pub;
int (*key_compare)(const Key *, const Key *) = strict_type ?
key_equal : key_equal_public;
if ((f = fopen(filename, "r")) == NULL) {
if (errno == ENOENT) {
debug("%s: keyfile \"%s\" missing", __func__, filename);
return 0;
} else {
error("%s: could not open keyfile \"%s\": %s", __func__,
filename, strerror(errno));
return -1;
}
}
while (read_keyfile_line(f, filename, line, sizeof(line),
&linenum) != -1) {
cp = line;
/* Skip leading whitespace. */
for (; *cp && (*cp == ' ' || *cp == '\t'); cp++)
;
/* Skip comments and empty lines */
switch (*cp) {
case '#':
case '\n':
case '\0':
continue;
}
pub = key_new(KEY_UNSPEC);
if (key_read(pub, &cp) != 1) {
key_free(pub);
continue;
}
if (key_compare(key, pub)) {
ret = 1;
key_free(pub);
break;
}
key_free(pub);
}
fclose(f);
return ret;
}
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