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