1 /* $OpenBSD: gss-serv-krb5.c,v 1.8 2013/07/20 01:55:13 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 #ifdef GSSAPI 28 #ifdef KRB5 29 30 #include <sys/types.h> 31 32 #include "xmalloc.h" 33 #include "key.h" 34 #include "hostfile.h" 35 #include "auth.h" 36 #include "log.h" 37 38 #include "buffer.h" 39 #include "ssh-gss.h" 40 41 #include <krb5.h> 42 #include <gssapi/gssapi_krb5.h> 43 44 static krb5_context krb_context = NULL; 45 46 /* Initialise the krb5 library, for the stuff that GSSAPI won't do */ 47 48 static int 49 ssh_gssapi_krb5_init(void) 50 { 51 krb5_error_code problem; 52 53 if (krb_context != NULL) 54 return 1; 55 56 problem = krb5_init_context(&krb_context); 57 if (problem) { 58 logit("Cannot initialize krb5 context"); 59 return 0; 60 } 61 krb5_init_ets(krb_context); 62 63 return 1; 64 } 65 66 /* Check if this user is OK to login. This only works with krb5 - other 67 * GSSAPI mechanisms will need their own. 68 * Returns true if the user is OK to log in, otherwise returns 0 69 */ 70 71 static int 72 ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name) 73 { 74 krb5_principal princ; 75 int retval; 76 const char *errmsg; 77 78 if (ssh_gssapi_krb5_init() == 0) 79 return 0; 80 81 if ((retval = krb5_parse_name(krb_context, client->exportedname.value, 82 &princ))) { 83 errmsg = krb5_get_error_message(krb_context, retval); 84 logit("krb5_parse_name(): %.100s", errmsg); 85 krb5_free_error_message(krb_context, errmsg); 86 return 0; 87 } 88 if (krb5_kuserok(krb_context, princ, name)) { 89 retval = 1; 90 logit("Authorized to %s, krb5 principal %s (krb5_kuserok)", 91 name, (char *)client->displayname.value); 92 } else 93 retval = 0; 94 95 krb5_free_principal(krb_context, princ); 96 return retval; 97 } 98 99 100 /* This writes out any forwarded credentials from the structure populated 101 * during userauth. Called after we have setuid to the user */ 102 103 static void 104 ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client) 105 { 106 krb5_ccache ccache; 107 krb5_error_code problem; 108 krb5_principal princ; 109 OM_uint32 maj_status, min_status; 110 const char *errmsg; 111 112 if (client->creds == NULL) { 113 debug("No credentials stored"); 114 return; 115 } 116 117 if (ssh_gssapi_krb5_init() == 0) 118 return; 119 120 if ((problem = krb5_cc_new_unique(krb_context, krb5_fcc_ops.prefix, 121 NULL, &ccache)) != 0) { 122 errmsg = krb5_get_error_message(krb_context, problem); 123 logit("krb5_cc_new_unique(): %.100s", errmsg); 124 krb5_free_error_message(krb_context, errmsg); 125 return; 126 } 127 128 if ((problem = krb5_parse_name(krb_context, 129 client->exportedname.value, &princ))) { 130 errmsg = krb5_get_error_message(krb_context, problem); 131 logit("krb5_parse_name(): %.100s", errmsg); 132 krb5_free_error_message(krb_context, errmsg); 133 krb5_cc_destroy(krb_context, ccache); 134 return; 135 } 136 137 if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) { 138 errmsg = krb5_get_error_message(krb_context, problem); 139 logit("krb5_cc_initialize(): %.100s", errmsg); 140 krb5_free_error_message(krb_context, errmsg); 141 krb5_free_principal(krb_context, princ); 142 krb5_cc_destroy(krb_context, ccache); 143 return; 144 } 145 146 krb5_free_principal(krb_context, princ); 147 148 if ((maj_status = gss_krb5_copy_ccache(&min_status, 149 client->creds, ccache))) { 150 logit("gss_krb5_copy_ccache() failed"); 151 krb5_cc_destroy(krb_context, ccache); 152 return; 153 } 154 155 client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache)); 156 client->store.envvar = "KRB5CCNAME"; 157 client->store.envval = xstrdup(client->store.filename); 158 159 krb5_cc_close(krb_context, ccache); 160 161 return; 162 } 163 164 ssh_gssapi_mech gssapi_kerberos_mech = { 165 "toWM5Slw5Ew8Mqkay+al2g==", 166 "Kerberos", 167 {9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"}, 168 NULL, 169 &ssh_gssapi_krb5_userok, 170 NULL, 171 &ssh_gssapi_krb5_storecreds 172 }; 173 174 #endif /* KRB5 */ 175 176 #endif /* GSSAPI */ 177