1 /* $OpenBSD: auth-krb5.c,v 1.22 2016/05/04 14:22:33 markus Exp $ */ 2 /* 3 * Kerberos v5 authentication and ticket-passing routines. 4 * 5 * From: FreeBSD: src/crypto/openssh/auth-krb5.c,v 1.6 2001/02/13 16:58:04 assar 6 */ 7 /* 8 * Copyright (c) 2002 Daniel Kouril. All rights reserved. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 #include "includes.h" 32 33 #include <sys/types.h> 34 #include <pwd.h> 35 #include <stdarg.h> 36 37 #include "xmalloc.h" 38 #include "ssh.h" 39 #include "packet.h" 40 #include "log.h" 41 #include "buffer.h" 42 #include "misc.h" 43 #include "servconf.h" 44 #include "uidswap.h" 45 #include "key.h" 46 #include "hostfile.h" 47 #include "auth.h" 48 49 #ifdef KRB5 50 #include <errno.h> 51 #include <unistd.h> 52 #include <string.h> 53 #include <krb5.h> 54 55 extern ServerOptions options; 56 57 static int 58 krb5_init(void *context) 59 { 60 Authctxt *authctxt = (Authctxt *)context; 61 krb5_error_code problem; 62 63 if (authctxt->krb5_ctx == NULL) { 64 problem = krb5_init_context(&authctxt->krb5_ctx); 65 if (problem) 66 return (problem); 67 } 68 return (0); 69 } 70 71 int 72 auth_krb5_password(Authctxt *authctxt, const char *password) 73 { 74 #ifndef HEIMDAL 75 krb5_creds creds; 76 krb5_principal server; 77 #endif 78 krb5_error_code problem; 79 krb5_ccache ccache = NULL; 80 int len; 81 char *client, *platform_client; 82 const char *errmsg; 83 84 /* get platform-specific kerberos client principal name (if it exists) */ 85 platform_client = platform_krb5_get_principal_name(authctxt->pw->pw_name); 86 client = platform_client ? platform_client : authctxt->pw->pw_name; 87 88 temporarily_use_uid(authctxt->pw); 89 90 problem = krb5_init(authctxt); 91 if (problem) 92 goto out; 93 94 problem = krb5_parse_name(authctxt->krb5_ctx, client, 95 &authctxt->krb5_user); 96 if (problem) 97 goto out; 98 99 #ifdef HEIMDAL 100 # ifdef HAVE_KRB5_CC_NEW_UNIQUE 101 problem = krb5_cc_new_unique(authctxt->krb5_ctx, 102 krb5_mcc_ops.prefix, NULL, &ccache); 103 # else 104 problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops, &ccache); 105 # endif 106 if (problem) 107 goto out; 108 109 problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache, 110 authctxt->krb5_user); 111 if (problem) 112 goto out; 113 114 restore_uid(); 115 116 problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user, 117 ccache, password, 1, NULL); 118 119 temporarily_use_uid(authctxt->pw); 120 121 if (problem) 122 goto out; 123 124 # ifdef HAVE_KRB5_CC_NEW_UNIQUE 125 problem = krb5_cc_new_unique(authctxt->krb5_ctx, 126 krb5_fcc_ops.prefix, NULL, &authctxt->krb5_fwd_ccache); 127 # else 128 problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops, 129 &authctxt->krb5_fwd_ccache); 130 # endif 131 if (problem) 132 goto out; 133 134 problem = krb5_cc_copy_cache(authctxt->krb5_ctx, ccache, 135 authctxt->krb5_fwd_ccache); 136 krb5_cc_destroy(authctxt->krb5_ctx, ccache); 137 ccache = NULL; 138 if (problem) 139 goto out; 140 141 #else 142 problem = krb5_get_init_creds_password(authctxt->krb5_ctx, &creds, 143 authctxt->krb5_user, (char *)password, NULL, NULL, 0, NULL, NULL); 144 if (problem) 145 goto out; 146 147 problem = krb5_sname_to_principal(authctxt->krb5_ctx, NULL, NULL, 148 KRB5_NT_SRV_HST, &server); 149 if (problem) 150 goto out; 151 152 restore_uid(); 153 problem = krb5_verify_init_creds(authctxt->krb5_ctx, &creds, server, 154 NULL, NULL, NULL); 155 krb5_free_principal(authctxt->krb5_ctx, server); 156 temporarily_use_uid(authctxt->pw); 157 if (problem) 158 goto out; 159 160 if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user, 161 authctxt->pw->pw_name)) { 162 problem = -1; 163 goto out; 164 } 165 166 problem = ssh_krb5_cc_gen(authctxt->krb5_ctx, &authctxt->krb5_fwd_ccache); 167 if (problem) 168 goto out; 169 170 problem = krb5_cc_initialize(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache, 171 authctxt->krb5_user); 172 if (problem) 173 goto out; 174 175 problem= krb5_cc_store_cred(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache, 176 &creds); 177 if (problem) 178 goto out; 179 #endif 180 181 authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache); 182 183 len = strlen(authctxt->krb5_ticket_file) + 6; 184 authctxt->krb5_ccname = xmalloc(len); 185 snprintf(authctxt->krb5_ccname, len, "FILE:%s", 186 authctxt->krb5_ticket_file); 187 188 #ifdef USE_PAM 189 if (options.use_pam) 190 do_pam_putenv("KRB5CCNAME", authctxt->krb5_ccname); 191 #endif 192 193 out: 194 restore_uid(); 195 196 free(platform_client); 197 198 if (problem) { 199 if (ccache) 200 krb5_cc_destroy(authctxt->krb5_ctx, ccache); 201 202 if (authctxt->krb5_ctx != NULL && problem!=-1) { 203 errmsg = krb5_get_error_message(authctxt->krb5_ctx, 204 problem); 205 debug("Kerberos password authentication failed: %s", 206 errmsg); 207 krb5_free_error_message(authctxt->krb5_ctx, errmsg); 208 } else 209 debug("Kerberos password authentication failed: %d", 210 problem); 211 212 krb5_cleanup_proc(authctxt); 213 214 if (options.kerberos_or_local_passwd) 215 return (-1); 216 else 217 return (0); 218 } 219 return (authctxt->valid ? 1 : 0); 220 } 221 222 void 223 krb5_cleanup_proc(Authctxt *authctxt) 224 { 225 debug("krb5_cleanup_proc called"); 226 if (authctxt->krb5_fwd_ccache) { 227 krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache); 228 authctxt->krb5_fwd_ccache = NULL; 229 } 230 if (authctxt->krb5_user) { 231 krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user); 232 authctxt->krb5_user = NULL; 233 } 234 if (authctxt->krb5_ctx) { 235 krb5_free_context(authctxt->krb5_ctx); 236 authctxt->krb5_ctx = NULL; 237 } 238 } 239 240 #ifndef HEIMDAL 241 krb5_error_code 242 ssh_krb5_cc_gen(krb5_context ctx, krb5_ccache *ccache) { 243 int tmpfd, ret, oerrno; 244 char ccname[40]; 245 mode_t old_umask; 246 247 ret = snprintf(ccname, sizeof(ccname), 248 "FILE:/tmp/krb5cc_%d_XXXXXXXXXX", geteuid()); 249 if (ret < 0 || (size_t)ret >= sizeof(ccname)) 250 return ENOMEM; 251 252 old_umask = umask(0177); 253 tmpfd = mkstemp(ccname + strlen("FILE:")); 254 oerrno = errno; 255 umask(old_umask); 256 if (tmpfd == -1) { 257 logit("mkstemp(): %.100s", strerror(oerrno)); 258 return oerrno; 259 } 260 261 if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) { 262 oerrno = errno; 263 logit("fchmod(): %.100s", strerror(oerrno)); 264 close(tmpfd); 265 return oerrno; 266 } 267 close(tmpfd); 268 269 return (krb5_cc_resolve(ctx, ccname, ccache)); 270 } 271 #endif /* !HEIMDAL */ 272 #endif /* KRB5 */ 273