/* $OpenBSD: gss-serv-krb5.c,v 1.7 2006/08/03 03:34:42 deraadt Exp $ */ /* * Copyright (c) 2001-2007 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 #include #include #include "xmalloc.h" #include "key.h" #include "hostfile.h" #include "auth.h" #include "log.h" #include "servconf.h" #include "buffer.h" #include "ssh-gss.h" extern ServerOptions options; #ifdef HEIMDAL # include #elif !defined(MECHGLUE) # ifdef HAVE_GSSAPI_KRB5_H # include # elif HAVE_GSSAPI_GSSAPI_KRB5_H # include # endif #endif static krb5_context krb_context = NULL; static int ssh_gssapi_krb5_init(); static int ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name); static int ssh_gssapi_krb5_localname(ssh_gssapi_client *client, char **user); static void ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client); static int ssh_gssapi_krb5_updatecreds(ssh_gssapi_ccache *store, ssh_gssapi_client *client); ssh_gssapi_mech gssapi_kerberos_mech = { "toWM5Slw5Ew8Mqkay+al2g==", "Kerberos", {9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"}, NULL, &ssh_gssapi_krb5_userok, &ssh_gssapi_krb5_localname, &ssh_gssapi_krb5_storecreds, &ssh_gssapi_krb5_updatecreds }; /* 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; if (ssh_gssapi_krb5_init() == 0) return 0; if ((retval = krb5_parse_name(krb_context, client->exportedname.value, &princ))) { logit("krb5_parse_name(): %.100s", krb5_get_err_text(krb_context, retval)); 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; } /* Retrieve the local username associated with a set of Kerberos * credentials. Hopefully we can use this for the 'empty' username * logins discussed in the draft */ static int ssh_gssapi_krb5_localname(ssh_gssapi_client *client, char **user) { krb5_principal princ; int retval; if (ssh_gssapi_krb5_init() == 0) return 0; if ((retval=krb5_parse_name(krb_context, client->displayname.value, &princ))) { logit("krb5_parse_name(): %.100s", krb5_get_err_text(krb_context,retval)); return 0; } /* We've got to return a malloc'd string */ *user = (char *)xmalloc(256); if (krb5_aname_to_localname(krb_context, princ, 256, *user)) { xfree(*user); *user = NULL; return(0); } return(1); } /* 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; gss_cred_id_t krb5_cred_handle; int len; const char *new_ccname; if (client->creds == NULL) { debug("No credentials stored"); return; } if (ssh_gssapi_krb5_init() == 0) return; #ifdef HEIMDAL 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)); return; } #else if ((problem = ssh_krb5_cc_gen(krb_context, &ccache))) { logit("ssh_krb5_cc_gen(): %.100s", krb5_get_err_text(krb_context, problem)); return; } #endif /* #ifdef HEIMDAL */ if ((problem = krb5_parse_name(krb_context, client->exportedname.value, &princ))) { logit("krb5_parse_name(): %.100s", krb5_get_err_text(krb_context, problem)); krb5_cc_destroy(krb_context, ccache); return; } if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) { logit("krb5_cc_initialize(): %.100s", krb5_get_err_text(krb_context, problem)); krb5_free_principal(krb_context, princ); krb5_cc_destroy(krb_context, ccache); return; } krb5_free_principal(krb_context, princ); #ifdef MECHGLUE krb5_cred_handle = __gss_get_mechanism_cred(client->creds, &(gssapi_kerberos_mech.oid)); #else krb5_cred_handle = client->creds; #endif if ((maj_status = gss_krb5_copy_ccache(&min_status, krb5_cred_handle, ccache))) { logit("gss_krb5_copy_ccache() failed"); krb5_cc_destroy(krb_context, ccache); return; } new_ccname = krb5_cc_get_name(krb_context, ccache); client->store.envvar = "KRB5CCNAME"; #ifdef USE_CCAPI xasprintf(&client->store.envval, "API:%s", new_ccname); client->store.filename = NULL; #else xasprintf(&client->store.envval, "FILE:%s", new_ccname); client->store.filename = xstrdup(new_ccname); #endif #ifdef USE_PAM if (options.use_pam) do_pam_putenv(client->store.envvar, client->store.envval); #endif krb5_cc_close(krb_context, ccache); return; } static int ssh_gssapi_krb5_updatecreds(ssh_gssapi_ccache *store, ssh_gssapi_client *client) { krb5_ccache ccache = NULL; krb5_principal principal = NULL; char *name = NULL; krb5_error_code problem; OM_uint32 maj_status, min_status; if ((problem = krb5_cc_resolve(krb_context, store->envval, &ccache))) { logit("krb5_cc_resolve(): %.100s", krb5_get_err_text(krb_context, problem)); return 0; } /* Find out who the principal in this cache is */ if ((problem = krb5_cc_get_principal(krb_context, ccache, &principal))) { logit("krb5_cc_get_principal(): %.100s", krb5_get_err_text(krb_context, problem)); krb5_cc_close(krb_context, ccache); return 0; } if ((problem = krb5_unparse_name(krb_context, principal, &name))) { logit("krb5_unparse_name(): %.100s", krb5_get_err_text(krb_context, problem)); krb5_free_principal(krb_context, principal); krb5_cc_close(krb_context, ccache); return 0; } if (strcmp(name,client->exportedname.value)!=0) { debug("Name in local credentials cache differs. Not storing"); krb5_free_principal(krb_context, principal); krb5_cc_close(krb_context, ccache); krb5_free_unparsed_name(krb_context, name); return 0; } krb5_free_unparsed_name(krb_context, name); /* Name matches, so lets get on with it! */ if ((problem = krb5_cc_initialize(krb_context, ccache, principal))) { logit("krb5_cc_initialize(): %.100s", krb5_get_err_text(krb_context, problem)); krb5_free_principal(krb_context, principal); krb5_cc_close(krb_context, ccache); return 0; } krb5_free_principal(krb_context, principal); if ((maj_status = gss_krb5_copy_ccache(&min_status, client->creds, ccache))) { logit("gss_krb5_copy_ccache() failed. Sorry!"); krb5_cc_close(krb_context, ccache); return 0; } return 1; } #endif /* KRB5 */ #endif /* GSSAPI */