209 lines
4.9 KiB
C
209 lines
4.9 KiB
C
/*
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* Copyright (c) 2002 Markus Friedl. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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RCSID("$OpenBSD: ssh-keysign.c,v 1.4 2002/06/19 00:27:55 deraadt Exp $");
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#include <openssl/evp.h>
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#include "log.h"
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#include "key.h"
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#include "ssh2.h"
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#include "misc.h"
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#include "xmalloc.h"
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#include "buffer.h"
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#include "bufaux.h"
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#include "authfile.h"
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#include "msg.h"
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#include "canohost.h"
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#include "pathnames.h"
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static int
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valid_request(struct passwd *pw, char *host, Key **ret, u_char *data,
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u_int datalen)
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{
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Buffer b;
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Key *key;
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u_char *pkblob;
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u_int blen, len;
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char *pkalg, *p;
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int pktype, fail;
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fail = 0;
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buffer_init(&b);
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buffer_append(&b, data, datalen);
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/* session id, currently limited to SHA1 (20 bytes) */
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p = buffer_get_string(&b, &len);
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if (len != 20)
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fail++;
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xfree(p);
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if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
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fail++;
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/* server user */
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buffer_skip_string(&b);
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/* service */
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p = buffer_get_string(&b, NULL);
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if (strcmp("ssh-connection", p) != 0)
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fail++;
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xfree(p);
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/* method */
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p = buffer_get_string(&b, NULL);
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if (strcmp("hostbased", p) != 0)
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fail++;
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xfree(p);
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/* pubkey */
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pkalg = buffer_get_string(&b, NULL);
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pkblob = buffer_get_string(&b, &blen);
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pktype = key_type_from_name(pkalg);
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if (pktype == KEY_UNSPEC)
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fail++;
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else if ((key = key_from_blob(pkblob, blen)) == NULL)
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fail++;
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else if (key->type != pktype)
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fail++;
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xfree(pkalg);
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xfree(pkblob);
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/* client host name, handle trailing dot */
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p = buffer_get_string(&b, &len);
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debug2("valid_request: check expect chost %s got %s", host, p);
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if (strlen(host) != len - 1)
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fail++;
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else if (p[len - 1] != '.')
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fail++;
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else if (strncasecmp(host, p, len - 1) != 0)
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fail++;
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xfree(p);
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/* local user */
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p = buffer_get_string(&b, NULL);
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if (strcmp(pw->pw_name, p) != 0)
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fail++;
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xfree(p);
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/* end of message */
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if (buffer_len(&b) != 0)
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fail++;
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debug3("valid_request: fail %d", fail);
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if (fail && key != NULL)
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key_free(key);
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else
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*ret = key;
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return (fail ? -1 : 0);
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}
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int
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main(int argc, char **argv)
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{
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Buffer b;
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Key *keys[2], *key;
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struct passwd *pw;
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int key_fd[2], i, found, version = 2, fd;
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u_char *signature, *data;
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char *host;
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u_int slen, dlen;
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key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
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key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
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seteuid(getuid());
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setuid(getuid());
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#ifdef DEBUG_SSH_KEYSIGN
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log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
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#endif
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if (key_fd[0] == -1 && key_fd[1] == -1)
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fatal("could not open any host key");
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if ((pw = getpwuid(getuid())) == NULL)
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fatal("getpwuid failed");
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pw = pwcopy(pw);
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SSLeay_add_all_algorithms();
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found = 0;
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for (i = 0; i < 2; i++) {
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keys[i] = NULL;
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if (key_fd[i] == -1)
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continue;
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keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
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NULL, NULL);
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close(key_fd[i]);
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if (keys[i] != NULL)
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found = 1;
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}
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if (!found)
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fatal("no hostkey found");
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buffer_init(&b);
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if (msg_recv(STDIN_FILENO, &b) < 0)
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fatal("msg_recv failed");
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if (buffer_get_char(&b) != version)
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fatal("bad version");
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fd = buffer_get_int(&b);
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if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO))
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fatal("bad fd");
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if ((host = get_local_name(fd)) == NULL)
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fatal("cannot get sockname for fd");
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data = buffer_get_string(&b, &dlen);
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if (valid_request(pw, host, &key, data, dlen) < 0)
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fatal("not a valid request");
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xfree(data);
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xfree(host);
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found = 0;
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for (i = 0; i < 2; i++) {
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if (keys[i] != NULL &&
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key_equal(key, keys[i])) {
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found = 1;
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break;
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}
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}
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if (!found)
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fatal("no matching hostkey found");
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if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
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fatal("key_sign failed");
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/* send reply */
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buffer_clear(&b);
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buffer_put_string(&b, signature, slen);
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msg_send(STDOUT_FILENO, version, &b);
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return (0);
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}
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