openssh-portable/ssh-keysign.c

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/* $OpenBSD: ssh-keysign.c,v 1.42 2014/04/29 18:01:49 markus Exp $ */
/*
* 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.
*/
- deraadt@cvs.openbsd.org 2006/08/03 03:34:42 [OVERVIEW atomicio.c atomicio.h auth-bsdauth.c auth-chall.c auth-krb5.c] [auth-options.c auth-options.h auth-passwd.c auth-rh-rsa.c auth-rhosts.c] [auth-rsa.c auth-skey.c auth.c auth.h auth1.c auth2-chall.c auth2-gss.c] [auth2-hostbased.c auth2-kbdint.c auth2-none.c auth2-passwd.c ] [auth2-pubkey.c auth2.c authfd.c authfd.h authfile.c bufaux.c bufbn.c] [buffer.c buffer.h canohost.c channels.c channels.h cipher-3des1.c] [cipher-bf1.c cipher-ctr.c cipher.c cleanup.c clientloop.c compat.c] [compress.c deattack.c dh.c dispatch.c dns.c dns.h fatal.c groupaccess.c] [groupaccess.h gss-genr.c gss-serv-krb5.c gss-serv.c hostfile.c kex.c] [kex.h kexdh.c kexdhc.c kexdhs.c kexgex.c kexgexc.c kexgexs.c key.c] [key.h log.c log.h mac.c match.c md-sha256.c misc.c misc.h moduli.c] [monitor.c monitor_fdpass.c monitor_mm.c monitor_mm.h monitor_wrap.c] [monitor_wrap.h msg.c nchan.c packet.c progressmeter.c readconf.c] [readconf.h readpass.c rsa.c scard.c scard.h scp.c servconf.c servconf.h] [serverloop.c session.c session.h sftp-client.c sftp-common.c] [sftp-common.h sftp-glob.c sftp-server.c sftp.c ssh-add.c ssh-agent.c] [ssh-dss.c ssh-gss.h ssh-keygen.c ssh-keyscan.c ssh-keysign.c ssh-rsa.c] [ssh.c ssh.h sshconnect.c sshconnect.h sshconnect1.c sshconnect2.c] [sshd.c sshlogin.c sshlogin.h sshpty.c sshpty.h sshtty.c ttymodes.c] [uidswap.c uidswap.h uuencode.c uuencode.h xmalloc.c xmalloc.h] [loginrec.c loginrec.h openbsd-compat/port-aix.c openbsd-compat/port-tun.h] almost entirely get rid of the culture of ".h files that include .h files" ok djm, sort of ok stevesk makes the pain stop in one easy step NB. portable commit contains everything *except* removing includes.h, as that will take a fair bit more work as we move headers that are required for portability workarounds to defines.h. (also, this step wasn't "easy")
2006-08-05 04:39:39 +02:00
#include "includes.h"
#include <fcntl.h>
#ifdef HAVE_PATHS_H
#include <paths.h>
#endif
#include <pwd.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <openssl/evp.h>
#include <openssl/rand.h>
#include <openssl/rsa.h>
- deraadt@cvs.openbsd.org 2006/08/03 03:34:42 [OVERVIEW atomicio.c atomicio.h auth-bsdauth.c auth-chall.c auth-krb5.c] [auth-options.c auth-options.h auth-passwd.c auth-rh-rsa.c auth-rhosts.c] [auth-rsa.c auth-skey.c auth.c auth.h auth1.c auth2-chall.c auth2-gss.c] [auth2-hostbased.c auth2-kbdint.c auth2-none.c auth2-passwd.c ] [auth2-pubkey.c auth2.c authfd.c authfd.h authfile.c bufaux.c bufbn.c] [buffer.c buffer.h canohost.c channels.c channels.h cipher-3des1.c] [cipher-bf1.c cipher-ctr.c cipher.c cleanup.c clientloop.c compat.c] [compress.c deattack.c dh.c dispatch.c dns.c dns.h fatal.c groupaccess.c] [groupaccess.h gss-genr.c gss-serv-krb5.c gss-serv.c hostfile.c kex.c] [kex.h kexdh.c kexdhc.c kexdhs.c kexgex.c kexgexc.c kexgexs.c key.c] [key.h log.c log.h mac.c match.c md-sha256.c misc.c misc.h moduli.c] [monitor.c monitor_fdpass.c monitor_mm.c monitor_mm.h monitor_wrap.c] [monitor_wrap.h msg.c nchan.c packet.c progressmeter.c readconf.c] [readconf.h readpass.c rsa.c scard.c scard.h scp.c servconf.c servconf.h] [serverloop.c session.c session.h sftp-client.c sftp-common.c] [sftp-common.h sftp-glob.c sftp-server.c sftp.c ssh-add.c ssh-agent.c] [ssh-dss.c ssh-gss.h ssh-keygen.c ssh-keyscan.c ssh-keysign.c ssh-rsa.c] [ssh.c ssh.h sshconnect.c sshconnect.h sshconnect1.c sshconnect2.c] [sshd.c sshlogin.c sshlogin.h sshpty.c sshpty.h sshtty.c ttymodes.c] [uidswap.c uidswap.h uuencode.c uuencode.h xmalloc.c xmalloc.h] [loginrec.c loginrec.h openbsd-compat/port-aix.c openbsd-compat/port-tun.h] almost entirely get rid of the culture of ".h files that include .h files" ok djm, sort of ok stevesk makes the pain stop in one easy step NB. portable commit contains everything *except* removing includes.h, as that will take a fair bit more work as we move headers that are required for portability workarounds to defines.h. (also, this step wasn't "easy")
2006-08-05 04:39:39 +02:00
#include "xmalloc.h"
#include "log.h"
#include "key.h"
#include "ssh.h"
#include "ssh2.h"
#include "misc.h"
#include "buffer.h"
#include "authfile.h"
#include "msg.h"
#include "canohost.h"
#include "pathnames.h"
#include "readconf.h"
#include "uidswap.h"
/* XXX readconf.c needs these */
uid_t original_real_uid;
extern char *__progname;
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) or SHA256 (32) */
p = buffer_get_string(&b, &len);
if (len != 20 && len != 32)
fail++;
free(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++;
free(p);
/* method */
p = buffer_get_string(&b, NULL);
if (strcmp("hostbased", p) != 0)
fail++;
free(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++;
free(pkalg);
free(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++;
free(p);
/* local user */
p = buffer_get_string(&b, NULL);
if (strcmp(pw->pw_name, p) != 0)
fail++;
free(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;
#define NUM_KEYTYPES 4
Key *keys[NUM_KEYTYPES], *key = NULL;
struct passwd *pw;
int key_fd[NUM_KEYTYPES], i, found, version = 2, fd;
u_char *signature, *data;
char *host, *fp;
u_int slen, dlen;
u_int32_t rnd[256];
/* Ensure that stdin and stdout are connected */
if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2)
exit(1);
/* Leave /dev/null fd iff it is attached to stderr */
if (fd > 2)
close(fd);
i = 0;
key_fd[i++] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
key_fd[i++] = open(_PATH_HOST_ECDSA_KEY_FILE, O_RDONLY);
key_fd[i++] = open(_PATH_HOST_ED25519_KEY_FILE, O_RDONLY);
key_fd[i++] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
original_real_uid = getuid(); /* XXX readconf.c needs this */
if ((pw = getpwuid(original_real_uid)) == NULL)
fatal("getpwuid failed");
pw = pwcopy(pw);
permanently_set_uid(pw);
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seed_rng();
#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 */
initialize_options(&options);
(void)read_config_file(_PATH_HOST_CONFIG_FILE, pw, "", &options, 0);
fill_default_options(&options);
if (options.enable_ssh_keysign != 1)
fatal("ssh-keysign not enabled in %s",
_PATH_HOST_CONFIG_FILE);
for (i = found = 0; i < NUM_KEYTYPES; i++) {
if (key_fd[i] != -1)
found = 1;
}
if (found == 0)
fatal("could not open any host key");
OpenSSL_add_all_algorithms();
arc4random_buf(rnd, sizeof(rnd));
RAND_seed(rnd, sizeof(rnd));
found = 0;
for (i = 0; i < NUM_KEYTYPES; i++) {
keys[i] = NULL;
if (key_fd[i] == -1)
continue;
#ifdef WITH_OPENSSL
/* XXX wrong api */
keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
NULL, NULL);
#endif
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 local name for fd");
data = buffer_get_string(&b, &dlen);
if (valid_request(pw, host, &key, data, dlen) < 0)
fatal("not a valid request");
free(host);
found = 0;
for (i = 0; i < NUM_KEYTYPES; i++) {
if (keys[i] != NULL &&
key_equal_public(key, keys[i])) {
found = 1;
break;
}
}
if (!found) {
fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
fatal("no matching hostkey found for key %s %s",
key_type(key), fp);
}
if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
fatal("key_sign failed");
free(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);
}