GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: usr.bin/ssh/ssh-keysign/../ssh-keysign.c Lines: 0 149 0.0 %
Date: 2017-11-13 Branches: 0 112 0.0 %

Line Branch Exec Source
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/* $OpenBSD: ssh-keysign.c,v 1.52 2016/02/15 09:47:49 dtucker 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 <sys/types.h>
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#include <openssl/evp.h>
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#include <openssl/rsa.h>
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#include <fcntl.h>
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#include <paths.h>
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#include <pwd.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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#include <errno.h>
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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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extern char *__progname;
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/* XXX readconf.c needs these */
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uid_t original_real_uid;
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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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	ssh_malloc_init();	/* must be called before any mallocs */
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	if (pledge("stdio rpath getpw dns id flock cpath wpath", NULL) != 0)
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		fatal("%s: pledge: %s", __progname, strerror(errno));
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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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#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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	OpenSSL_add_all_algorithms();
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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 (pledge("stdio dns flock rpath cpath wpath", NULL) != 0)
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		fatal("%s: pledge: %s", __progname, strerror(errno));
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	if ((b = sshbuf_new()) == NULL)
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		fatal("%s: sshbuf_new failed", __progname);
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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", __progname, 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", __progname, 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", __progname, 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", __progname);
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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, NULL, 0))
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	    != 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", __progname, 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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}