1 files changed, 211 insertions, 0 deletions
diff --git a/gss-serv-krb5.c b/gss-serv-krb5.c
new file mode 100644
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+/* $OpenBSD: gss-serv-krb5.c,v 1.9 2018/07/09 21:37:55 markus Exp $ */
+
+/*
+ * Copyright (c) 2001-2003 Simon Wilkinson. 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"
+
+#ifdef GSSAPI
+#ifdef KRB5
+
+#include <sys/types.h>
+
+#include <stdarg.h>
+#include <string.h>
+
+#include "xmalloc.h"
+#include "sshkey.h"
+#include "hostfile.h"
+#include "auth.h"
+#include "log.h"
+#include "misc.h"
+#include "servconf.h"
+
+#include "ssh-gss.h"
+
+extern ServerOptions options;
+
+#ifdef HEIMDAL
+# include <krb5.h>
+#endif
+#ifdef HAVE_GSSAPI_KRB5_H
+# include <gssapi_krb5.h>
+#elif HAVE_GSSAPI_GSSAPI_KRB5_H
+# include <gssapi/gssapi_krb5.h>
+#endif
+
+static krb5_context krb_context = NULL;
+
+/* Initialise the krb5 library, for the stuff that GSSAPI won't do */
+
+static int
+ssh_gssapi_krb5_init(void)
+{
+	krb5_error_code problem;
+
+	if (krb_context != NULL)
+		return 1;
+
+	problem = krb5_init_context(&krb_context);
+	if (problem) {
+		logit("Cannot initialize krb5 context");
+		return 0;
+	}
+
+	return 1;
+}
+
+/* Check if this user is OK to login. This only works with krb5 - other
+ * GSSAPI mechanisms will need their own.
+ * Returns true if the user is OK to log in, otherwise returns 0
+ */
+
+static int
+ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name)
+{
+	krb5_principal princ;
+	int retval;
+	const char *errmsg;
+
+	if (ssh_gssapi_krb5_init() == 0)
+		return 0;
+
+	if ((retval = krb5_parse_name(krb_context, client->exportedname.value,
+	    &princ))) {
+		errmsg = krb5_get_error_message(krb_context, retval);
+		logit("krb5_parse_name(): %.100s", errmsg);
+		krb5_free_error_message(krb_context, errmsg);
+		return 0;
+	}
+	if (krb5_kuserok(krb_context, princ, name)) {
+		retval = 1;
+		logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",
+		    name, (char *)client->displayname.value);
+	} else
+		retval = 0;
+
+	krb5_free_principal(krb_context, princ);
+	return retval;
+}
+
+
+/* This writes out any forwarded credentials from the structure populated
+ * during userauth. Called after we have setuid to the user */
+
+static void
+ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
+{
+	krb5_ccache ccache;
+	krb5_error_code problem;
+	krb5_principal princ;
+	OM_uint32 maj_status, min_status;
+	int len;
+	const char *errmsg;
+
+	if (client->creds == NULL) {
+		debug("No credentials stored");
+		return;
+	}
+
+	if (ssh_gssapi_krb5_init() == 0)
+		return;
+
+#ifdef HEIMDAL
+# ifdef HAVE_KRB5_CC_NEW_UNIQUE
+	if ((problem = krb5_cc_new_unique(krb_context, krb5_fcc_ops.prefix,
+	    NULL, &ccache)) != 0) {
+		errmsg = krb5_get_error_message(krb_context, problem);
+		logit("krb5_cc_new_unique(): %.100s", errmsg);
+# else
+	if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) {
+	    logit("krb5_cc_gen_new(): %.100s",
+		krb5_get_err_text(krb_context, problem));
+# endif
+		krb5_free_error_message(krb_context, errmsg);
+		return;
+	}
+#else
+	if ((problem = ssh_krb5_cc_gen(krb_context, &ccache))) {
+		errmsg = krb5_get_error_message(krb_context, problem);
+		logit("ssh_krb5_cc_gen(): %.100s", errmsg);
+		krb5_free_error_message(krb_context, errmsg);
+		return;
+	}
+#endif	/* #ifdef HEIMDAL */
+
+	if ((problem = krb5_parse_name(krb_context,
+	    client->exportedname.value, &princ))) {
+		errmsg = krb5_get_error_message(krb_context, problem);
+		logit("krb5_parse_name(): %.100s", errmsg);
+		krb5_free_error_message(krb_context, errmsg);
+		return;
+	}
+
+	if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) {
+		errmsg = krb5_get_error_message(krb_context, problem);
+		logit("krb5_cc_initialize(): %.100s", errmsg);
+		krb5_free_error_message(krb_context, errmsg);
+		krb5_free_principal(krb_context, princ);
+		krb5_cc_destroy(krb_context, ccache);
+		return;
+	}
+
+	krb5_free_principal(krb_context, princ);
+
+	if ((maj_status = gss_krb5_copy_ccache(&min_status,
+	    client->creds, ccache))) {
+		logit("gss_krb5_copy_ccache() failed");
+		krb5_cc_destroy(krb_context, ccache);
+		return;
+	}
+
+	client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache));
+	client->store.envvar = "KRB5CCNAME";
+	len = strlen(client->store.filename) + 6;
+	client->store.envval = xmalloc(len);
+	snprintf(client->store.envval, len, "FILE:%s", client->store.filename);
+
+#ifdef USE_PAM
+	if (options.use_pam)
+		do_pam_putenv(client->store.envvar, client->store.envval);
+#endif
+
+	krb5_cc_close(krb_context, ccache);
+
+	return;
+}
+
+ssh_gssapi_mech gssapi_kerberos_mech = {
+	"toWM5Slw5Ew8Mqkay+al2g==",
+	"Kerberos",
+	{9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
+	NULL,
+	&ssh_gssapi_krb5_userok,
+	NULL,
+	&ssh_gssapi_krb5_storecreds
+};
+
+#endif /* KRB5 */
+
+#endif /* GSSAPI */