[gssapi-openssh.git] / openssh / ssh-keysign.c

/*
 * Copyright (c) 2002 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 "includes.h"
RCSID("$OpenBSD: ssh-keysign.c,v 1.13 2003/07/03 08:09:06 djm Exp $");

#include <openssl/evp.h>
#include <openssl/rand.h>
#include <openssl/rsa.h>

#include "log.h"
#include "key.h"
#include "ssh.h"
#include "ssh2.h"
#include "misc.h"
#include "xmalloc.h"
#include "buffer.h"
#include "bufaux.h"
#include "authfile.h"
#include "msg.h"
#include "canohost.h"
#include "pathnames.h"
#include "readconf.h"

/* XXX readconf.c needs these */
uid_t original_real_uid;

#ifdef HAVE___PROGNAME
extern char *__progname;
#else
char *__progname;
#endif

static int
valid_request(struct passwd *pw, char *host, Key **ret, u_char *data,
    u_int datalen)
{
	Buffer b;
	Key *key = NULL;
	u_char *pkblob;
	u_int blen, len;
	char *pkalg, *p;
	int pktype, fail;

	fail = 0;

	buffer_init(&b);
	buffer_append(&b, data, datalen);

	/* session id, currently limited to SHA1 (20 bytes) */
	p = buffer_get_string(&b, &len);
	if (len != 20)
		fail++;
	xfree(p);

	if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
		fail++;

	/* server user */
	buffer_skip_string(&b);

	/* service */
	p = buffer_get_string(&b, NULL);
	if (strcmp("ssh-connection", p) != 0)
		fail++;
	xfree(p);

	/* method */
	p = buffer_get_string(&b, NULL);
	if (strcmp("hostbased", p) != 0)
		fail++;
	xfree(p);

	/* pubkey */
	pkalg = buffer_get_string(&b, NULL);
	pkblob = buffer_get_string(&b, &blen);

	pktype = key_type_from_name(pkalg);
	if (pktype == KEY_UNSPEC)
		fail++;
	else if ((key = key_from_blob(pkblob, blen)) == NULL)
		fail++;
	else if (key->type != pktype)
		fail++;
	xfree(pkalg);
	xfree(pkblob);

	/* client host name, handle trailing dot */
	p = buffer_get_string(&b, &len);
	debug2("valid_request: check expect chost %s got %s", host, p);
	if (strlen(host) != len - 1)
		fail++;
	else if (p[len - 1] != '.')
		fail++;
	else if (strncasecmp(host, p, len - 1) != 0)
		fail++;
	xfree(p);

	/* local user */
	p = buffer_get_string(&b, NULL);

	if (strcmp(pw->pw_name, p) != 0)
		fail++;
	xfree(p);

	/* end of message */
	if (buffer_len(&b) != 0)
		fail++;

	debug3("valid_request: fail %d", fail);

	if (fail && key != NULL)
		key_free(key);
	else
		*ret = key;

	return (fail ? -1 : 0);
}

int
main(int argc, char **argv)
{
	Buffer b;
	Options options;
	Key *keys[2], *key;
	struct passwd *pw;
	int key_fd[2], i, found, version = 2, fd;
	u_char *signature, *data;
	char *host;
	u_int slen, dlen;
	u_int32_t rnd[256];

	key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
	key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);

	seteuid(getuid());
	setuid(getuid());

	init_rng();
	seed_rng();
	arc4random_stir();

#ifdef DEBUG_SSH_KEYSIGN
	log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
#endif

	/* verify that ssh-keysign is enabled by the admin */
	original_real_uid = getuid();	/* XXX readconf.c needs this */
	initialize_options(&options);
	(void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options);
	fill_default_options(&options);
	if (options.enable_ssh_keysign != 1)
		fatal("ssh-keysign not enabled in %s",
		    _PATH_HOST_CONFIG_FILE);

	if (key_fd[0] == -1 && key_fd[1] == -1)
		fatal("could not open any host key");

	if ((pw = getpwuid(getuid())) == NULL)
		fatal("getpwuid failed");
	pw = pwcopy(pw);

	SSLeay_add_all_algorithms();
	for (i = 0; i < 256; i++)
		rnd[i] = arc4random();
	RAND_seed(rnd, sizeof(rnd));

	found = 0;
	for (i = 0; i < 2; i++) {
		keys[i] = NULL;
		if (key_fd[i] == -1)
			continue;
		keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
		    NULL, NULL);
		close(key_fd[i]);
		if (keys[i] != NULL)
			found = 1;
	}
	if (!found)
		fatal("no hostkey found");

	buffer_init(&b);
	if (ssh_msg_recv(STDIN_FILENO, &b) < 0)
		fatal("ssh_msg_recv failed");
	if (buffer_get_char(&b) != version)
		fatal("bad version");
	fd = buffer_get_int(&b);
	if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO))
		fatal("bad fd");
	if ((host = get_local_name(fd)) == NULL)
		fatal("cannot get sockname for fd");

	data = buffer_get_string(&b, &dlen);
	if (valid_request(pw, host, &key, data, dlen) < 0)
		fatal("not a valid request");
	xfree(host);

	found = 0;
	for (i = 0; i < 2; i++) {
		if (keys[i] != NULL &&
		    key_equal(key, keys[i])) {
			found = 1;
			break;
		}
	}
	if (!found)
		fatal("no matching hostkey found");

	if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
		fatal("key_sign failed");
	xfree(data);

	/* send reply */
	buffer_clear(&b);
	buffer_put_string(&b, signature, slen);
	ssh_msg_send(STDOUT_FILENO, version, &b);

	return (0);
}
Commit	Line	Data
f5799ae1	1	/*
	2	* Copyright (c) 2002 Markus Friedl. All rights reserved.
	3	*
	4	* Redistribution and use in source and binary forms, with or without
	5	* modification, are permitted provided that the following conditions
	6	* are met:
	7	* 1. Redistributions of source code must retain the above copyright
	8	* notice, this list of conditions and the following disclaimer.
	9	* 2. Redistributions in binary form must reproduce the above copyright
	10	* notice, this list of conditions and the following disclaimer in the
	11	* documentation and/or other materials provided with the distribution.
	12	*
	13	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	14	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	15	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	16	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	17	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	18	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	19	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	20	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	21	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	22	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	23	*/
	24	#include "includes.h"
0fff78ff	25	RCSID("$OpenBSD: ssh-keysign.c,v 1.13 2003/07/03 08:09:06 djm Exp $");
f5799ae1	26
f5799ae1	27	#include <openssl/evp.h>
41b2f314	28	#include <openssl/rand.h>
41b2f314	29	#include <openssl/rsa.h>
f5799ae1	30
	31	#include "log.h"
	32	#include "key.h"
41b2f314	33	#include "ssh.h"
f5799ae1	34	#include "ssh2.h"
	35	#include "misc.h"
	36	#include "xmalloc.h"
	37	#include "buffer.h"
	38	#include "bufaux.h"
	39	#include "authfile.h"
	40	#include "msg.h"
	41	#include "canohost.h"
	42	#include "pathnames.h"
41b2f314	43	#include "readconf.h"
41b2f314	44
0fff78ff	45	/* XXX readconf.c needs these */
0fff78ff	46	uid_t original_real_uid;
f5799ae1	47
	48	#ifdef HAVE___PROGNAME
	49	extern char *__progname;
	50	#else
	51	char *__progname;
	52	#endif
	53
	54	static int
	55	valid_request(struct passwd pw, char host, Key *ret, u_char data,
	56	u_int datalen)
	57	{
	58	Buffer b;
0fff78ff	59	Key *key = NULL;
f5799ae1	60	u_char *pkblob;
	61	u_int blen, len;
	62	char pkalg, p;
	63	int pktype, fail;
	64
	65	fail = 0;
	66
	67	buffer_init(&b);
	68	buffer_append(&b, data, datalen);
	69
	70	/* session id, currently limited to SHA1 (20 bytes) */
	71	p = buffer_get_string(&b, &len);
	72	if (len != 20)
	73	fail++;
	74	xfree(p);
	75
	76	if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
	77	fail++;
	78
	79	/* server user */
	80	buffer_skip_string(&b);
	81
	82	/* service */
	83	p = buffer_get_string(&b, NULL);
	84	if (strcmp("ssh-connection", p) != 0)
	85	fail++;
	86	xfree(p);
	87
	88	/* method */
	89	p = buffer_get_string(&b, NULL);
	90	if (strcmp("hostbased", p) != 0)
	91	fail++;
	92	xfree(p);
	93
	94	/* pubkey */
	95	pkalg = buffer_get_string(&b, NULL);
	96	pkblob = buffer_get_string(&b, &blen);
	97
	98	pktype = key_type_from_name(pkalg);
	99	if (pktype == KEY_UNSPEC)
	100	fail++;
	101	else if ((key = key_from_blob(pkblob, blen)) == NULL)
	102	fail++;
	103	else if (key->type != pktype)
	104	fail++;
	105	xfree(pkalg);
	106	xfree(pkblob);
	107
	108	/* client host name, handle trailing dot */
	109	p = buffer_get_string(&b, &len);
	110	debug2("valid_request: check expect chost %s got %s", host, p);
	111	if (strlen(host) != len - 1)
	112	fail++;
	113	else if (p[len - 1] != '.')
	114	fail++;
	115	else if (strncasecmp(host, p, len - 1) != 0)
	116	fail++;
	117	xfree(p);
	118
	119	/* local user */
	120	p = buffer_get_string(&b, NULL);
	121
	122	if (strcmp(pw->pw_name, p) != 0)
	123	fail++;
124	xfree(p);
125
126	/* end of message */
127	if (buffer_len(&b) != 0)
128	fail++;
129
130	debug3("valid_request: fail %d", fail);
131
132	if (fail && key != NULL)
133	key_free(key);
134	else
135	*ret = key;
136
137	return (fail ? -1 : 0);
138	}
139
140	int
141	main(int argc, char **argv)
142	{
143	Buffer b;
41b2f314	144	Options options;
f5799ae1	145	Key keys[2], key;
	146	struct passwd *pw;
	147	int key_fd[2], i, found, version = 2, fd;
	148	u_char signature, data;
	149	char *host;
	150	u_int slen, dlen;
41b2f314	151	u_int32_t rnd[256];
f5799ae1	152
	153	key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
	154	key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
	155
	156	seteuid(getuid());
	157	setuid(getuid());
	158
	159	init_rng();
	160	seed_rng();
	161	arc4random_stir();
	162
	163	#ifdef DEBUG_SSH_KEYSIGN
	164	log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
	165	#endif
	166
41b2f314	167	/* verify that ssh-keysign is enabled by the admin */
	168	original_real_uid = getuid(); /* XXX readconf.c needs this */
	169	initialize_options(&options);
	170	(void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options);
	171	fill_default_options(&options);
6a9b3198	172	if (options.enable_ssh_keysign != 1)
6a9b3198	173	fatal("ssh-keysign not enabled in %s",
41b2f314	174	_PATH_HOST_CONFIG_FILE);
41b2f314	175
f5799ae1	176	if (key_fd[0] == -1 && key_fd[1] == -1)
	177	fatal("could not open any host key");
	178
	179	if ((pw = getpwuid(getuid())) == NULL)
	180	fatal("getpwuid failed");
	181	pw = pwcopy(pw);
	182
	183	SSLeay_add_all_algorithms();
41b2f314	184	for (i = 0; i < 256; i++)
	185	rnd[i] = arc4random();
	186	RAND_seed(rnd, sizeof(rnd));
f5799ae1	187
	188	found = 0;
	189	for (i = 0; i < 2; i++) {
	190	keys[i] = NULL;
	191	if (key_fd[i] == -1)
	192	continue;
	193	keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
	194	NULL, NULL);
	195	close(key_fd[i]);
	196	if (keys[i] != NULL)
	197	found = 1;
	198	}
	199	if (!found)
	200	fatal("no hostkey found");
	201
	202	buffer_init(&b);
41b2f314	203	if (ssh_msg_recv(STDIN_FILENO, &b) < 0)
41b2f314	204	fatal("ssh_msg_recv failed");
f5799ae1	205	if (buffer_get_char(&b) != version)
	206	fatal("bad version");
	207	fd = buffer_get_int(&b);
	208	if ((fd == STDIN_FILENO) \|\| (fd == STDOUT_FILENO))
	209	fatal("bad fd");
	210	if ((host = get_local_name(fd)) == NULL)
	211	fatal("cannot get sockname for fd");
	212
	213	data = buffer_get_string(&b, &dlen);
	214	if (valid_request(pw, host, &key, data, dlen) < 0)
	215	fatal("not a valid request");
f5799ae1	216	xfree(host);
	217
	218	found = 0;
	219	for (i = 0; i < 2; i++) {
	220	if (keys[i] != NULL &&
	221	key_equal(key, keys[i])) {
	222	found = 1;
	223	break;
	224	}
	225	}
	226	if (!found)
	227	fatal("no matching hostkey found");
	228
	229	if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
	230	fatal("key_sign failed");
41b2f314	231	xfree(data);
f5799ae1	232
	233	/* send reply */
	234	buffer_clear(&b);
	235	buffer_put_string(&b, signature, slen);
41b2f314	236	ssh_msg_send(STDOUT_FILENO, version, &b);
f5799ae1	237
	238	return (0);
	239	}