[openssh.git] / 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 1.7 2002/07/03 14:21:05 markus 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"

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

#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;
	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.hostbased_authentication != 1)
		fatal("Hostbased authentication 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 && keys[i]->type == KEY_RSA) {
			if (RSA_blinding_on(keys[i]->rsa, NULL) != 1) {
				error("RSA_blinding_on failed");
				key_free(keys[i]);
				keys[i] = NULL;
			}
		}
		if (keys[i] != NULL)
			found = 1;
	}
	if (!found)
		fatal("no hostkey found");

	buffer_init(&b);
	if (msg_recv(STDIN_FILENO, &b) < 0)
		fatal("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);
	msg_send(STDOUT_FILENO, version, &b);

	return (0);
}
Commit	Line	Data
39c00dc2	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"
60cd0a97	25	RCSID("$OpenBSD: ssh-keysign.c,v 1.7 2002/07/03 14:21:05 markus Exp $");
39c00dc2	26
39c00dc2	27	#include <openssl/evp.h>
261189cc	28	#include <openssl/rand.h>
261189cc	29	#include <openssl/rsa.h>
39c00dc2	30
	31	#include "log.h"
	32	#include "key.h"
60cd0a97	33	#include "ssh.h"
39c00dc2	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"
60cd0a97	43	#include "readconf.h"
	44
	45	uid_t original_real_uid; /* XXX readconf.c needs this */
39c00dc2	46
95d5ebf7	47	#ifdef HAVE___PROGNAME
	48	extern char *__progname;
	49	#else
	50	char *__progname;
	51	#endif
	52
39c00dc2	53	static int
	54	valid_request(struct passwd pw, char host, Key *ret, u_char data,
	55	u_int datalen)
	56	{
	57	Buffer b;
	58	Key *key;
	59	u_char *pkblob;
	60	u_int blen, len;
	61	char pkalg, p;
	62	int pktype, fail;
	63
	64	fail = 0;
	65
	66	buffer_init(&b);
	67	buffer_append(&b, data, datalen);
7203d6bb	68
1f143cf2	69	/* session id, currently limited to SHA1 (20 bytes) */
	70	p = buffer_get_string(&b, &len);
	71	if (len != 20)
	72	fail++;
	73	xfree(p);
	74
39c00dc2	75	if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
	76	fail++;
	77
	78	/* server user */
	79	buffer_skip_string(&b);
	80
	81	/* service */
	82	p = buffer_get_string(&b, NULL);
	83	if (strcmp("ssh-connection", p) != 0)
	84	fail++;
	85	xfree(p);
	86
	87	/* method */
	88	p = buffer_get_string(&b, NULL);
	89	if (strcmp("hostbased", p) != 0)
	90	fail++;
	91	xfree(p);
	92
	93	/* pubkey */
	94	pkalg = buffer_get_string(&b, NULL);
	95	pkblob = buffer_get_string(&b, &blen);
	96
	97	pktype = key_type_from_name(pkalg);
	98	if (pktype == KEY_UNSPEC)
	99	fail++;
	100	else if ((key = key_from_blob(pkblob, blen)) == NULL)
	101	fail++;
	102	else if (key->type != pktype)
	103	fail++;
	104	xfree(pkalg);
	105	xfree(pkblob);
	106
	107	/* client host name, handle trailing dot */
	108	p = buffer_get_string(&b, &len);
	109	debug2("valid_request: check expect chost %s got %s", host, p);
	110	if (strlen(host) != len - 1)
	111	fail++;
	112	else if (p[len - 1] != '.')
7203d6bb	113	fail++;
39c00dc2	114	else if (strncasecmp(host, p, len - 1) != 0)
7203d6bb	115	fail++;
39c00dc2	116	xfree(p);
	117
	118	/* local user */
	119	p = buffer_get_string(&b, NULL);
	120
	121	if (strcmp(pw->pw_name, p) != 0)
	122	fail++;
	123	xfree(p);
	124
	125	/* end of message */
	126	if (buffer_len(&b) != 0)
	127	fail++;
	128
	129	debug3("valid_request: fail %d", fail);
	130
	131	if (fail && key != NULL)
	132	key_free(key);
	133	else
	134	*ret = key;
	135
	136	return (fail ? -1 : 0);
	137	}
	138
	139	int
	140	main(int argc, char **argv)
	141	{
	142	Buffer b;
60cd0a97	143	Options options;
39c00dc2	144	Key keys[2], key;
	145	struct passwd *pw;
	146	int key_fd[2], i, found, version = 2, fd;
	147	u_char signature, data;
	148	char *host;
	149	u_int slen, dlen;
261189cc	150	u_int32_t rnd[256];
39c00dc2	151
	152	key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
	153	key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
	154
	155	seteuid(getuid());
	156	setuid(getuid());
	157
875ec275	158	init_rng();
	159	seed_rng();
	160	arc4random_stir();
04eb391d	161
39c00dc2	162	#ifdef DEBUG_SSH_KEYSIGN
39c00dc2	163	log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
7203d6bb	164	#endif
39c00dc2	165
60cd0a97	166	/* verify that ssh-keysign is enabled by the admin */
	167	original_real_uid = getuid(); /* XXX readconf.c needs this */
	168	initialize_options(&options);
	169	(void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options);
	170	fill_default_options(&options);
	171	if (options.hostbased_authentication != 1)
	172	fatal("Hostbased authentication not enabled in %s",
	173	_PATH_HOST_CONFIG_FILE);
	174
39c00dc2	175	if (key_fd[0] == -1 && key_fd[1] == -1)
	176	fatal("could not open any host key");
	177
	178	if ((pw = getpwuid(getuid())) == NULL)
	179	fatal("getpwuid failed");
7203d6bb	180	pw = pwcopy(pw);
39c00dc2	181
39c00dc2	182	SSLeay_add_all_algorithms();
261189cc	183	for (i = 0; i < 256; i++)
	184	rnd[i] = arc4random();
	185	RAND_seed(rnd, sizeof(rnd));
39c00dc2	186
	187	found = 0;
	188	for (i = 0; i < 2; i++) {
	189	keys[i] = NULL;
	190	if (key_fd[i] == -1)
	191	continue;
	192	keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
	193	NULL, NULL);
	194	close(key_fd[i]);
261189cc	195	if (keys[i] != NULL && keys[i]->type == KEY_RSA) {
	196	if (RSA_blinding_on(keys[i]->rsa, NULL) != 1) {
	197	error("RSA_blinding_on failed");
	198	key_free(keys[i]);
	199	keys[i] = NULL;
	200	}
	201	}
39c00dc2	202	if (keys[i] != NULL)
	203	found = 1;
	204	}
	205	if (!found)
	206	fatal("no hostkey found");
	207
	208	buffer_init(&b);
	209	if (msg_recv(STDIN_FILENO, &b) < 0)
	210	fatal("msg_recv failed");
	211	if (buffer_get_char(&b) != version)
	212	fatal("bad version");
	213	fd = buffer_get_int(&b);
	214	if ((fd == STDIN_FILENO) \|\| (fd == STDOUT_FILENO))
	215	fatal("bad fd");
	216	if ((host = get_local_name(fd)) == NULL)
	217	fatal("cannot get sockname for fd");
7203d6bb	218
39c00dc2	219	data = buffer_get_string(&b, &dlen);
	220	if (valid_request(pw, host, &key, data, dlen) < 0)
	221	fatal("not a valid request");
39c00dc2	222	xfree(host);
	223
	224	found = 0;
	225	for (i = 0; i < 2; i++) {
	226	if (keys[i] != NULL &&
	227	key_equal(key, keys[i])) {
	228	found = 1;
	229	break;
	230	}
	231	}
	232	if (!found)
	233	fatal("no matching hostkey found");
	234
	235	if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
	236	fatal("key_sign failed");
20e79e98	237	xfree(data);
7203d6bb	238
39c00dc2	239	/* send reply */
	240	buffer_clear(&b);
	241	buffer_put_string(&b, signature, slen);
	242	msg_send(STDOUT_FILENO, version, &b);
	243
	244	return (0);
	245	}