Put ssh back into the repository
Change-Id: I23324372188fa6ed3f93a32b84365f5df6367590
diff --git a/ssh-keysign.c b/ssh-keysign.c
new file mode 100644
index 0000000..1deb7e1
--- /dev/null
+++ b/ssh-keysign.c
@@ -0,0 +1,260 @@
+/* $OpenBSD: ssh-keysign.c,v 1.36 2011/02/16 00:31:14 djm 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;
+#define NUM_KEYTYPES 3
+ 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;
+ 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_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);
+
+ 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);
+
+ 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();
+ for (i = 0; i < 256; i++)
+ rnd[i] = arc4random();
+ RAND_seed(rnd, sizeof(rnd));
+
+ found = 0;
+ for (i = 0; i < NUM_KEYTYPES; 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 local name 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 < NUM_KEYTYPES; i++) {
+ if (keys[i] != NULL &&
+ key_equal_public(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);
+}