gss-serv-krb5.c revision 1.13
1 /* $NetBSD: gss-serv-krb5.c,v 1.13 2026/04/08 18:58:40 christos Exp $ */ 2 /* $OpenBSD: gss-serv-krb5.c,v 1.10 2026/02/08 15:28:01 dtucker Exp $ */ 3 4 /* 5 * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include "includes.h" 29 __RCSID("$NetBSD: gss-serv-krb5.c,v 1.13 2026/04/08 18:58:40 christos Exp $"); 30 #ifdef GSSAPI 31 #ifdef KRB5 32 33 #include <sys/types.h> 34 35 #include <stdarg.h> 36 #include <string.h> 37 38 #include "xmalloc.h" 39 #include "sshkey.h" 40 #include "hostfile.h" 41 #include "auth.h" 42 #include "log.h" 43 #include "misc.h" 44 #include "servconf.h" 45 46 #include "ssh-gss.h" 47 48 extern ServerOptions options; 49 50 #include <krb5.h> 51 #include <gssapi/gssapi_krb5.h> 52 53 static krb5_context krb_context = NULL; 54 55 /* Initialise the krb5 library, for the stuff that GSSAPI won't do */ 56 57 static int 58 ssh_gssapi_krb5_init(void) 59 { 60 krb5_error_code problem; 61 62 if (krb_context != NULL) 63 return 1; 64 65 problem = krb5_init_context(&krb_context); 66 if (problem) { 67 logit("Cannot initialize krb5 context"); 68 return 0; 69 } 70 #ifdef isneeded 71 krb5_init_ets(krb_context); 72 #endif 73 74 return 1; 75 } 76 77 /* Check if this user is OK to login. This only works with krb5 - other 78 * GSSAPI mechanisms will need their own. 79 * Returns true if the user is OK to log in, otherwise returns 0 80 */ 81 82 static int 83 ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name) 84 { 85 krb5_principal princ; 86 int retval; 87 const char *errmsg; 88 89 if (ssh_gssapi_krb5_init() == 0) 90 return 0; 91 92 if ((retval = krb5_parse_name(krb_context, client->exportedname.value, 93 &princ))) { 94 errmsg = krb5_get_error_message(krb_context, retval); 95 logit("krb5_parse_name(): %.100s", errmsg); 96 krb5_free_error_message(krb_context, errmsg); 97 return 0; 98 } 99 if (krb5_kuserok(krb_context, princ, name)) { 100 retval = 1; 101 logit("Authorized to %s, krb5 principal %s (krb5_kuserok)", 102 name, (char *)client->displayname.value); 103 } else 104 retval = 0; 105 106 krb5_free_principal(krb_context, princ); 107 return retval; 108 } 109 110 111 /* This writes out any forwarded credentials from the structure populated 112 * during userauth. Called after we have setuid to the user */ 113 114 static void 115 ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client) 116 { 117 krb5_ccache ccache; 118 krb5_error_code problem; 119 krb5_principal princ; 120 OM_uint32 maj_status, min_status; 121 size_t len; 122 const char *errmsg; 123 124 if (client->creds == NULL) { 125 debug("No credentials stored"); 126 return; 127 } 128 129 if (ssh_gssapi_krb5_init() == 0) 130 return; 131 132 if ((problem = krb5_cc_new_unique(krb_context, krb5_fcc_ops.prefix, 133 NULL, &ccache)) != 0) { 134 errmsg = krb5_get_error_message(krb_context, problem); 135 logit("krb5_cc_new_unique(): %.100s", errmsg); 136 krb5_free_error_message(krb_context, errmsg); 137 return; 138 } 139 140 if ((problem = krb5_parse_name(krb_context, 141 client->exportedname.value, &princ))) { 142 errmsg = krb5_get_error_message(krb_context, problem); 143 logit("krb5_parse_name(): %.100s", errmsg); 144 krb5_free_error_message(krb_context, errmsg); 145 krb5_cc_destroy(krb_context, ccache); 146 return; 147 } 148 149 if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) { 150 errmsg = krb5_get_error_message(krb_context, problem); 151 logit("krb5_cc_initialize(): %.100s", errmsg); 152 krb5_free_error_message(krb_context, errmsg); 153 krb5_free_principal(krb_context, princ); 154 krb5_cc_destroy(krb_context, ccache); 155 return; 156 } 157 158 krb5_free_principal(krb_context, princ); 159 160 if ((maj_status = gss_krb5_copy_ccache(&min_status, 161 client->creds, ccache))) { 162 logit("gss_krb5_copy_ccache() failed"); 163 krb5_cc_destroy(krb_context, ccache); 164 return; 165 } 166 167 client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache)); 168 client->store.envvar = __UNCONST("KRB5CCNAME"); 169 len = strlen(client->store.filename) + 6; 170 client->store.envval = xmalloc(len); 171 snprintf(client->store.envval, len, "FILE:%s", client->store.filename); 172 173 #ifdef USE_PAM 174 if (options.use_pam) 175 do_pam_putenv(client->store.envvar, client->store.envval); 176 #endif 177 178 krb5_cc_close(krb_context, ccache); 179 180 return; 181 } 182 183 ssh_gssapi_mech gssapi_kerberos_mech = { 184 "toWM5Slw5Ew8Mqkay+al2g==", 185 "Kerberos", 186 {9, __UNCONST("\x2A\x86\x48\x86\xF7\x12\x01\x02\x02")}, 187 NULL, 188 &ssh_gssapi_krb5_userok, 189 NULL, 190 &ssh_gssapi_krb5_storecreds 191 }; 192 193 #endif /* KRB5 */ 194 195 #endif /* GSSAPI */ 196
Indexes created Wed Aug 05 00:25:39 UTC 2026