1 /* $OpenBSD: gss-serv-krb5.c,v 1.9 2018/07/09 21:37:55 markus 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 <sys/types.h> 33 34 #include <stdarg.h> 35 #include <string.h> 36 37 #include "xmalloc.h" 38 #include "sshkey.h" 39 #include "hostfile.h" 40 #include "auth.h" 41 #include "log.h" 42 #include "misc.h" 43 #include "servconf.h" 44 45 #include "ssh-gss.h" 46 47 extern ServerOptions options; 48 49 #ifdef HEIMDAL 50 # include <krb5.h> 51 #endif 52 #ifdef HAVE_GSSAPI_KRB5_H 53 # include <gssapi_krb5.h> 54 #elif HAVE_GSSAPI_GSSAPI_KRB5_H 55 # include <gssapi/gssapi_krb5.h> 56 #endif 57 58 static krb5_context krb_context = NULL; 59 60 /* Initialise the krb5 library, for the stuff that GSSAPI won't do */ 61 62 static int 63 ssh_gssapi_krb5_init(void) 64 { 65 krb5_error_code problem; 66 67 if (krb_context != NULL) 68 return 1; 69 70 problem = krb5_init_context(&krb_context); 71 if (problem) { 72 logit("Cannot initialize krb5 context"); 73 return 0; 74 } 75 76 return 1; 77 } 78 79 /* Check if this user is OK to login. This only works with krb5 - other 80 * GSSAPI mechanisms will need their own. 81 * Returns true if the user is OK to log in, otherwise returns 0 82 */ 83 84 static int 85 ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name) 86 { 87 krb5_principal princ; 88 int retval; 89 const char *errmsg; 90 91 if (ssh_gssapi_krb5_init() == 0) 92 return 0; 93 94 if ((retval = krb5_parse_name(krb_context, client->exportedname.value, 95 &princ))) { 96 errmsg = krb5_get_error_message(krb_context, retval); 97 logit("krb5_parse_name(): %.100s", errmsg); 98 krb5_free_error_message(krb_context, errmsg); 99 return 0; 100 } 101 if (krb5_kuserok(krb_context, princ, name)) { 102 retval = 1; 103 logit("Authorized to %s, krb5 principal %s (krb5_kuserok)", 104 name, (char *)client->displayname.value); 105 } else 106 retval = 0; 107 108 krb5_free_principal(krb_context, princ); 109 return retval; 110 } 111 112 113 /* This writes out any forwarded credentials from the structure populated 114 * during userauth. Called after we have setuid to the user */ 115 116 static void 117 ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client) 118 { 119 krb5_ccache ccache; 120 krb5_error_code problem; 121 krb5_principal princ; 122 OM_uint32 maj_status, min_status; 123 int len; 124 const char *errmsg; 125 126 if (client->creds == NULL) { 127 debug("No credentials stored"); 128 return; 129 } 130 131 if (ssh_gssapi_krb5_init() == 0) 132 return; 133 134 #ifdef HEIMDAL 135 # ifdef HAVE_KRB5_CC_NEW_UNIQUE 136 if ((problem = krb5_cc_new_unique(krb_context, krb5_fcc_ops.prefix, 137 NULL, &ccache)) != 0) { 138 errmsg = krb5_get_error_message(krb_context, problem); 139 logit("krb5_cc_new_unique(): %.100s", errmsg); 140 # else 141 if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) { 142 logit("krb5_cc_gen_new(): %.100s", 143 krb5_get_err_text(krb_context, problem)); 144 # endif 145 krb5_free_error_message(krb_context, errmsg); 146 return; 147 } 148 #else 149 if ((problem = ssh_krb5_cc_gen(krb_context, &ccache))) { 150 errmsg = krb5_get_error_message(krb_context, problem); 151 logit("ssh_krb5_cc_gen(): %.100s", errmsg); 152 krb5_free_error_message(krb_context, errmsg); 153 return; 154 } 155 #endif /* #ifdef HEIMDAL */ 156 157 if ((problem = krb5_parse_name(krb_context, 158 client->exportedname.value, &princ))) { 159 errmsg = krb5_get_error_message(krb_context, problem); 160 logit("krb5_parse_name(): %.100s", errmsg); 161 krb5_free_error_message(krb_context, errmsg); 162 return; 163 } 164 165 if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) { 166 errmsg = krb5_get_error_message(krb_context, problem); 167 logit("krb5_cc_initialize(): %.100s", errmsg); 168 krb5_free_error_message(krb_context, errmsg); 169 krb5_free_principal(krb_context, princ); 170 krb5_cc_destroy(krb_context, ccache); 171 return; 172 } 173 174 krb5_free_principal(krb_context, princ); 175 176 if ((maj_status = gss_krb5_copy_ccache(&min_status, 177 client->creds, ccache))) { 178 logit("gss_krb5_copy_ccache() failed"); 179 krb5_cc_destroy(krb_context, ccache); 180 return; 181 } 182 183 client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache)); 184 client->store.envvar = "KRB5CCNAME"; 185 len = strlen(client->store.filename) + 6; 186 client->store.envval = xmalloc(len); 187 snprintf(client->store.envval, len, "FILE:%s", client->store.filename); 188 189 #ifdef USE_PAM 190 if (options.use_pam) 191 do_pam_putenv(client->store.envvar, client->store.envval); 192 #endif 193 194 krb5_cc_close(krb_context, ccache); 195 196 return; 197 } 198 199 ssh_gssapi_mech gssapi_kerberos_mech = { 200 "toWM5Slw5Ew8Mqkay+al2g==", 201 "Kerberos", 202 {9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"}, 203 NULL, 204 &ssh_gssapi_krb5_userok, 205 NULL, 206 &ssh_gssapi_krb5_storecreds 207 }; 208 209 #endif /* KRB5 */ 210 211 #endif /* GSSAPI */ 212