diff options
Diffstat (limited to 'crypto/openssh/ssh-keysign.c')
| -rw-r--r-- | crypto/openssh/ssh-keysign.c | 254 |
1 files changed, 254 insertions, 0 deletions
diff --git a/crypto/openssh/ssh-keysign.c b/crypto/openssh/ssh-keysign.c new file mode 100644 index 0000000..c4bc7e5 --- /dev/null +++ b/crypto/openssh/ssh-keysign.c @@ -0,0 +1,254 @@ +/* $OpenBSD: ssh-keysign.c,v 1.29 2006/08/03 03:34:42 deraadt 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. + */ + +#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> + +#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++; + 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 = NULL; + 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]; + + /* 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); + + key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY); + key_fd[1] = open(_PATH_HOST_DSA_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); + + 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 */ + initialize_options(&options); + (void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options, 0); + 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"); + + 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); +} |
