| /* |
| * 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 1.6 2002/07/03 09:55:38 markus Exp $"); |
| |
| #include <openssl/evp.h> |
| #include <openssl/rand.h> |
| #include <openssl/rsa.h> |
| |
| #include "log.h" |
| #include "key.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" |
| |
| #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; |
| 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 |
| |
| 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); |
| } |