gss-serv-krb5.c revision 128456
1/* $OpenBSD: gss-serv-krb5.c,v 1.2 2003/11/21 11:57:03 djm Exp $ */ 2 3/* 4 * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27#include "includes.h" 28 29#ifdef GSSAPI 30#ifdef KRB5 31 32#include "auth.h" 33#include "xmalloc.h" 34#include "log.h" 35#include "servconf.h" 36 37#include "ssh-gss.h" 38 39extern ServerOptions options; 40 41#ifdef HEIMDAL 42# include <krb5.h> 43#else 44# ifdef HAVE_GSSAPI_KRB5 45# include <gssapi_krb5.h> 46# elif HAVE_GSSAPI_GSSAPI_KRB5 47# include <gssapi/gssapi_krb5.h> 48# endif 49#endif 50 51static krb5_context krb_context = NULL; 52 53/* Initialise the krb5 library, for the stuff that GSSAPI won't do */ 54 55static int 56ssh_gssapi_krb5_init() 57{ 58 krb5_error_code problem; 59 60 if (krb_context != NULL) 61 return 1; 62 63 problem = krb5_init_context(&krb_context); 64 if (problem) { 65 logit("Cannot initialize krb5 context"); 66 return 0; 67 } 68#ifdef KRB5_INIT_ETS 69 krb5_init_ets(krb_context); 70#endif 71 72 return 1; 73} 74 75/* Check if this user is OK to login. This only works with krb5 - other 76 * GSSAPI mechanisms will need their own. 77 * Returns true if the user is OK to log in, otherwise returns 0 78 */ 79 80static int 81ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name) 82{ 83 krb5_principal princ; 84 int retval; 85 86 if (ssh_gssapi_krb5_init() == 0) 87 return 0; 88 89 if ((retval = krb5_parse_name(krb_context, client->exportedname.value, 90 &princ))) { 91 logit("krb5_parse_name(): %.100s", 92 krb5_get_err_text(krb_context, retval)); 93 return 0; 94 } 95 if (krb5_kuserok(krb_context, princ, name)) { 96 retval = 1; 97 logit("Authorized to %s, krb5 principal %s (krb5_kuserok)", 98 name, (char *)client->displayname.value); 99 } else 100 retval = 0; 101 102 krb5_free_principal(krb_context, princ); 103 return retval; 104} 105 106 107/* This writes out any forwarded credentials from the structure populated 108 * during userauth. Called after we have setuid to the user */ 109 110static void 111ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client) 112{ 113 krb5_ccache ccache; 114 krb5_error_code problem; 115 krb5_principal princ; 116 OM_uint32 maj_status, min_status; 117 int len; 118 119 if (client->creds == NULL) { 120 debug("No credentials stored"); 121 return; 122 } 123 124 if (ssh_gssapi_krb5_init() == 0) 125 return; 126 127#ifdef HEIMDAL 128 if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) { 129 logit("krb5_cc_gen_new(): %.100s", 130 krb5_get_err_text(krb_context, problem)); 131 return; 132 } 133#else 134 { 135 int tmpfd; 136 char ccname[40]; 137 138 snprintf(ccname, sizeof(ccname), 139 "FILE:/tmp/krb5cc_%d_XXXXXX", geteuid()); 140 141 if ((tmpfd = mkstemp(ccname + strlen("FILE:"))) == -1) { 142 logit("mkstemp(): %.100s", strerror(errno)); 143 problem = errno; 144 return; 145 } 146 if (fchmod(tmpfd, S_IRUSR | S_IWUSR) == -1) { 147 logit("fchmod(): %.100s", strerror(errno)); 148 close(tmpfd); 149 problem = errno; 150 return; 151 } 152 close(tmpfd); 153 if ((problem = krb5_cc_resolve(krb_context, ccname, &ccache))) { 154 logit("krb5_cc_resolve(): %.100s", 155 krb5_get_err_text(krb_context, problem)); 156 return; 157 } 158 } 159#endif /* #ifdef HEIMDAL */ 160 161 if ((problem = krb5_parse_name(krb_context, 162 client->exportedname.value, &princ))) { 163 logit("krb5_parse_name(): %.100s", 164 krb5_get_err_text(krb_context, problem)); 165 krb5_cc_destroy(krb_context, ccache); 166 return; 167 } 168 169 if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) { 170 logit("krb5_cc_initialize(): %.100s", 171 krb5_get_err_text(krb_context, problem)); 172 krb5_free_principal(krb_context, princ); 173 krb5_cc_destroy(krb_context, ccache); 174 return; 175 } 176 177 krb5_free_principal(krb_context, princ); 178 179 if ((maj_status = gss_krb5_copy_ccache(&min_status, 180 client->creds, ccache))) { 181 logit("gss_krb5_copy_ccache() failed"); 182 krb5_cc_destroy(krb_context, ccache); 183 return; 184 } 185 186 client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache)); 187 client->store.envvar = "KRB5CCNAME"; 188 len = strlen(client->store.filename) + 6; 189 client->store.envval = xmalloc(len); 190 snprintf(client->store.envval, len, "FILE:%s", client->store.filename); 191 192#ifdef USE_PAM 193 if (options.use_pam) 194 do_pam_putenv(client->store.envvar, client->store.envval); 195#endif 196 197 krb5_cc_close(krb_context, ccache); 198 199 return; 200} 201 202ssh_gssapi_mech gssapi_kerberos_mech = { 203 "toWM5Slw5Ew8Mqkay+al2g==", 204 "Kerberos", 205 {9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"}, 206 NULL, 207 &ssh_gssapi_krb5_userok, 208 NULL, 209 &ssh_gssapi_krb5_storecreds 210}; 211 212#endif /* KRB5 */ 213 214#endif /* GSSAPI */ 215