b54c312497
2 known bugs: . Build doesn't copy libssh* to the destination directory. + workaround is to copy them from the lib directory to destination and recreate links . ssh_config and sshd_config don't install + workaround is to copy them manually Note the software doesn't build to completion until you do the workarounds. Still trying to sort this out, but wanted to get these changes up for more visibility and collaboration.
298 lines
8.0 KiB
C
298 lines
8.0 KiB
C
/* $OpenBSD: ssh-keysign.c,v 1.49 2015/07/03 03:56:25 djm Exp $ */
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/*
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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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#include <fcntl.h>
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#ifdef HAVE_PATHS_H
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#include <paths.h>
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#endif
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#include <pwd.h>
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#include <stdarg.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#ifdef WITH_OPENSSL
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#include <openssl/evp.h>
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#include <openssl/rand.h>
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#include <openssl/rsa.h>
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#endif
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#include "xmalloc.h"
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#include "log.h"
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#include "sshkey.h"
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#include "ssh.h"
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#include "ssh2.h"
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#include "misc.h"
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#include "sshbuf.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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#include "readconf.h"
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#include "uidswap.h"
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#include "sshkey.h"
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#include "ssherr.h"
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struct ssh *active_state = NULL; /* XXX needed for linking */
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/* XXX readconf.c needs these */
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uid_t original_real_uid;
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extern char *__progname;
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static int
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valid_request(struct passwd *pw, char *host, struct sshkey **ret,
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u_char *data, size_t datalen)
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{
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struct sshbuf *b;
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struct sshkey *key = NULL;
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u_char type, *pkblob;
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char *p;
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size_t blen, len;
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char *pkalg, *luser;
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int r, pktype, fail;
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if (ret != NULL)
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*ret = NULL;
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fail = 0;
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if ((b = sshbuf_from(data, datalen)) == NULL)
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fatal("%s: sshbuf_from failed", __func__);
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/* session id, currently limited to SHA1 (20 bytes) or SHA256 (32) */
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if ((r = sshbuf_get_string(b, NULL, &len)) != 0)
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fatal("%s: buffer error: %s", __func__, ssh_err(r));
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if (len != 20 && len != 32)
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fail++;
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if ((r = sshbuf_get_u8(b, &type)) != 0)
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fatal("%s: buffer error: %s", __func__, ssh_err(r));
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if (type != SSH2_MSG_USERAUTH_REQUEST)
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fail++;
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/* server user */
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if ((r = sshbuf_skip_string(b)) != 0)
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fatal("%s: buffer error: %s", __func__, ssh_err(r));
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/* service */
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if ((r = sshbuf_get_cstring(b, &p, NULL)) != 0)
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fatal("%s: buffer error: %s", __func__, ssh_err(r));
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if (strcmp("ssh-connection", p) != 0)
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fail++;
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free(p);
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/* method */
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if ((r = sshbuf_get_cstring(b, &p, NULL)) != 0)
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fatal("%s: buffer error: %s", __func__, ssh_err(r));
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if (strcmp("hostbased", p) != 0)
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fail++;
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free(p);
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/* pubkey */
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if ((r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 ||
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(r = sshbuf_get_string(b, &pkblob, &blen)) != 0)
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fatal("%s: buffer error: %s", __func__, ssh_err(r));
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pktype = sshkey_type_from_name(pkalg);
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if (pktype == KEY_UNSPEC)
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fail++;
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else if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
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error("%s: bad key blob: %s", __func__, ssh_err(r));
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fail++;
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} else if (key->type != pktype)
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fail++;
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free(pkalg);
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free(pkblob);
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/* client host name, handle trailing dot */
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if ((r = sshbuf_get_cstring(b, &p, &len)) != 0)
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fatal("%s: buffer error: %s", __func__, ssh_err(r));
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debug2("%s: check expect chost %s got %s", __func__, 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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free(p);
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/* local user */
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if ((r = sshbuf_get_cstring(b, &luser, NULL)) != 0)
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fatal("%s: buffer error: %s", __func__, ssh_err(r));
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if (strcmp(pw->pw_name, luser) != 0)
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fail++;
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free(luser);
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/* end of message */
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if (sshbuf_len(b) != 0)
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fail++;
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sshbuf_free(b);
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debug3("%s: fail %d", __func__, fail);
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if (fail && key != NULL)
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sshkey_free(key);
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else if (ret != NULL)
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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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struct sshbuf *b;
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Options options;
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#define NUM_KEYTYPES 4
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struct sshkey *keys[NUM_KEYTYPES], *key = NULL;
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struct passwd *pw;
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int r, key_fd[NUM_KEYTYPES], i, found, version = 2, fd;
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u_char *signature, *data, rver;
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char *host, *fp;
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size_t slen, dlen;
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#ifdef WITH_OPENSSL
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u_int32_t rnd[256];
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#endif
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/* Ensure that stdin and stdout are connected */
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if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2)
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exit(1);
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/* Leave /dev/null fd iff it is attached to stderr */
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if (fd > 2)
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close(fd);
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i = 0;
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/* XXX This really needs to read sshd_config for the paths */
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key_fd[i++] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
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key_fd[i++] = open(_PATH_HOST_ECDSA_KEY_FILE, O_RDONLY);
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key_fd[i++] = open(_PATH_HOST_ED25519_KEY_FILE, O_RDONLY);
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key_fd[i++] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
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original_real_uid = getuid(); /* XXX readconf.c needs this */
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if ((pw = getpwuid(original_real_uid)) == NULL)
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fatal("getpwuid failed");
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pw = pwcopy(pw);
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permanently_set_uid(pw);
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seed_rng();
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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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/* verify that ssh-keysign is enabled by the admin */
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initialize_options(&options);
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(void)read_config_file(_PATH_HOST_CONFIG_FILE, pw, "", "", &options, 0);
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fill_default_options(&options);
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if (options.enable_ssh_keysign != 1)
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fatal("ssh-keysign not enabled in %s",
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_PATH_HOST_CONFIG_FILE);
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for (i = found = 0; i < NUM_KEYTYPES; i++) {
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if (key_fd[i] != -1)
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found = 1;
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}
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if (found == 0)
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fatal("could not open any host key");
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#ifdef WITH_OPENSSL
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OpenSSL_add_all_algorithms();
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arc4random_buf(rnd, sizeof(rnd));
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RAND_seed(rnd, sizeof(rnd));
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#endif
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found = 0;
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for (i = 0; i < NUM_KEYTYPES; 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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r = sshkey_load_private_type_fd(key_fd[i], KEY_UNSPEC,
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NULL, &key, NULL);
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close(key_fd[i]);
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if (r != 0)
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debug("parse key %d: %s", i, ssh_err(r));
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else if (key != NULL) {
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keys[i] = key;
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found = 1;
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}
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}
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if (!found)
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fatal("no hostkey found");
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if ((b = sshbuf_new()) == NULL)
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fatal("%s: sshbuf_new failed", __func__);
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if (ssh_msg_recv(STDIN_FILENO, b) < 0)
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fatal("ssh_msg_recv failed");
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if ((r = sshbuf_get_u8(b, &rver)) != 0)
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fatal("%s: buffer error: %s", __func__, ssh_err(r));
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if (rver != version)
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fatal("bad version: received %d, expected %d", rver, version);
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if ((r = sshbuf_get_u32(b, (u_int *)&fd)) != 0)
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fatal("%s: buffer error: %s", __func__, ssh_err(r));
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if (fd < 0 || 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 local name for fd");
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if ((r = sshbuf_get_string(b, &data, &dlen)) != 0)
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fatal("%s: buffer error: %s", __func__, ssh_err(r));
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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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free(host);
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found = 0;
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for (i = 0; i < NUM_KEYTYPES; i++) {
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if (keys[i] != NULL &&
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sshkey_equal_public(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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if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
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SSH_FP_DEFAULT)) == NULL)
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fatal("%s: sshkey_fingerprint failed", __func__);
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fatal("no matching hostkey found for key %s %s",
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sshkey_type(key), fp ? fp : "");
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}
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if ((r = sshkey_sign(keys[i], &signature, &slen, data, dlen, 0)) != 0)
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fatal("sshkey_sign failed: %s", ssh_err(r));
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free(data);
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/* send reply */
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sshbuf_reset(b);
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if ((r = sshbuf_put_string(b, signature, slen)) != 0)
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fatal("%s: buffer error: %s", __func__, ssh_err(r));
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if (ssh_msg_send(STDOUT_FILENO, version, b) == -1)
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fatal("ssh_msg_send failed");
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return (0);
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}
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