[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 1.15 2004/01/19 21:25:15 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"

/* 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++;
	buffer_free(&b);

	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);
	if (ssh_msg_send(STDOUT_FILENO, version, &b) == -1)
		fatal("ssh_msg_send failed");

	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"
43f7a4b8	25	RCSID("$OpenBSD: ssh-keysign.c,v 1.15 2004/01/19 21:25:15 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"
60cd0a97	44
f811e52a	45	/* XXX readconf.c needs these */
f811e52a	46	uid_t original_real_uid;
39c00dc2	47
95d5ebf7	48	#ifdef HAVE___PROGNAME
	49	extern char *__progname;
	50	#else
	51	char *__progname;
	52	#endif
	53
39c00dc2	54	static int
	55	valid_request(struct passwd pw, char host, Key *ret, u_char data,
	56	u_int datalen)
	57	{
	58	Buffer b;
16f1b5ca	59	Key *key = NULL;
39c00dc2	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);
7203d6bb	69
1f143cf2	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
39c00dc2	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] != '.')
7203d6bb	114	fail++;
39c00dc2	115	else if (strncasecmp(host, p, len - 1) != 0)
7203d6bb	116	fail++;
39c00dc2	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++;
43f7a4b8	129	buffer_free(&b);
39c00dc2	130
	131	debug3("valid_request: fail %d", fail);
	132
	133	if (fail && key != NULL)
	134	key_free(key);
	135	else
	136	*ret = key;
	137
	138	return (fail ? -1 : 0);
	139	}
	140
	141	int
	142	main(int argc, char **argv)
	143	{
	144	Buffer b;
60cd0a97	145	Options options;
39c00dc2	146	Key keys[2], key;
	147	struct passwd *pw;
	148	int key_fd[2], i, found, version = 2, fd;
	149	u_char signature, data;
	150	char *host;
	151	u_int slen, dlen;
261189cc	152	u_int32_t rnd[256];
39c00dc2	153
	154	key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
	155	key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
	156
	157	seteuid(getuid());
	158	setuid(getuid());
	159
875ec275	160	init_rng();
	161	seed_rng();
	162	arc4random_stir();
04eb391d	163
39c00dc2	164	#ifdef DEBUG_SSH_KEYSIGN
39c00dc2	165	log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
7203d6bb	166	#endif
39c00dc2	167
60cd0a97	168	/* verify that ssh-keysign is enabled by the admin */
	169	original_real_uid = getuid(); /* XXX readconf.c needs this */
	170	initialize_options(&options);
	171	(void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options);
	172	fill_default_options(&options);
cc46e2ee	173	if (options.enable_ssh_keysign != 1)
cc46e2ee	174	fatal("ssh-keysign not enabled in %s",
60cd0a97	175	_PATH_HOST_CONFIG_FILE);
60cd0a97	176
39c00dc2	177	if (key_fd[0] == -1 && key_fd[1] == -1)
	178	fatal("could not open any host key");
	179
	180	if ((pw = getpwuid(getuid())) == NULL)
	181	fatal("getpwuid failed");
7203d6bb	182	pw = pwcopy(pw);
39c00dc2	183
39c00dc2	184	SSLeay_add_all_algorithms();
261189cc	185	for (i = 0; i < 256; i++)
	186	rnd[i] = arc4random();
	187	RAND_seed(rnd, sizeof(rnd));
39c00dc2	188
	189	found = 0;
	190	for (i = 0; i < 2; i++) {
	191	keys[i] = NULL;
	192	if (key_fd[i] == -1)
	193	continue;
	194	keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
	195	NULL, NULL);
	196	close(key_fd[i]);
	197	if (keys[i] != NULL)
	198	found = 1;
	199	}
	200	if (!found)
	201	fatal("no hostkey found");
	202
	203	buffer_init(&b);
e987fdbe	204	if (ssh_msg_recv(STDIN_FILENO, &b) < 0)
e987fdbe	205	fatal("ssh_msg_recv failed");
39c00dc2	206	if (buffer_get_char(&b) != version)
	207	fatal("bad version");
	208	fd = buffer_get_int(&b);
	209	if ((fd == STDIN_FILENO) \|\| (fd == STDOUT_FILENO))
	210	fatal("bad fd");
	211	if ((host = get_local_name(fd)) == NULL)
	212	fatal("cannot get sockname for fd");
7203d6bb	213
39c00dc2	214	data = buffer_get_string(&b, &dlen);
	215	if (valid_request(pw, host, &key, data, dlen) < 0)
	216	fatal("not a valid request");
39c00dc2	217	xfree(host);
	218
	219	found = 0;
	220	for (i = 0; i < 2; i++) {
	221	if (keys[i] != NULL &&
	222	key_equal(key, keys[i])) {
	223	found = 1;
	224	break;
	225	}
	226	}
	227	if (!found)
	228	fatal("no matching hostkey found");
	229
	230	if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
	231	fatal("key_sign failed");
20e79e98	232	xfree(data);
7203d6bb	233
39c00dc2	234	/* send reply */
	235	buffer_clear(&b);
	236	buffer_put_string(&b, signature, slen);
d3cbe6f8	237	if (ssh_msg_send(STDOUT_FILENO, version, &b) == -1)
d3cbe6f8	238	fatal("ssh_msg_send failed");
39c00dc2	239
	240	return (0);
	241	}