1 /* $OpenBSD: auth-krb5.c,v 1.24 2021/04/03 06:18:40 djm 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 "sshbuf.h" 42 #include "sshkey.h" 43 #include "misc.h" 44 #include "servconf.h" 45 #include "uidswap.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, 167 &authctxt->krb5_fwd_ccache); 168 if (problem) 169 goto out; 170 171 problem = krb5_cc_initialize(authctxt->krb5_ctx, 172 authctxt->krb5_fwd_ccache, authctxt->krb5_user); 173 if (problem) 174 goto out; 175 176 problem = krb5_cc_store_cred(authctxt->krb5_ctx, 177 authctxt->krb5_fwd_ccache, &creds); 178 if (problem) 179 goto out; 180 #endif 181 182 authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache); 183 184 len = strlen(authctxt->krb5_ticket_file) + 6; 185 authctxt->krb5_ccname = xmalloc(len); 186 snprintf(authctxt->krb5_ccname, len, "FILE:%s", 187 authctxt->krb5_ticket_file); 188 189 #ifdef USE_PAM 190 if (options.use_pam) 191 do_pam_putenv("KRB5CCNAME", authctxt->krb5_ccname); 192 #endif 193 194 out: 195 restore_uid(); 196 197 free(platform_client); 198 199 if (problem) { 200 if (ccache) 201 krb5_cc_destroy(authctxt->krb5_ctx, ccache); 202 203 if (authctxt->krb5_ctx != NULL && problem!=-1) { 204 errmsg = krb5_get_error_message(authctxt->krb5_ctx, 205 problem); 206 debug("Kerberos password authentication failed: %s", 207 errmsg); 208 krb5_free_error_message(authctxt->krb5_ctx, errmsg); 209 } else 210 debug("Kerberos password authentication failed: %d", 211 problem); 212 213 krb5_cleanup_proc(authctxt); 214 215 if (options.kerberos_or_local_passwd) 216 return (-1); 217 else 218 return (0); 219 } 220 return (authctxt->valid ? 1 : 0); 221 } 222 223 void 224 krb5_cleanup_proc(Authctxt *authctxt) 225 { 226 debug("krb5_cleanup_proc called"); 227 if (authctxt->krb5_fwd_ccache) { 228 krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache); 229 authctxt->krb5_fwd_ccache = NULL; 230 } 231 if (authctxt->krb5_user) { 232 krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user); 233 authctxt->krb5_user = NULL; 234 } 235 if (authctxt->krb5_ctx) { 236 krb5_free_context(authctxt->krb5_ctx); 237 authctxt->krb5_ctx = NULL; 238 } 239 } 240 241 #ifndef HEIMDAL 242 krb5_error_code 243 ssh_krb5_cc_gen(krb5_context ctx, krb5_ccache *ccache) { 244 int tmpfd, ret, oerrno; 245 char ccname[40]; 246 mode_t old_umask; 247 248 ret = snprintf(ccname, sizeof(ccname), 249 "FILE:/tmp/krb5cc_%d_XXXXXXXXXX", geteuid()); 250 if (ret < 0 || (size_t)ret >= sizeof(ccname)) 251 return ENOMEM; 252 253 old_umask = umask(0177); 254 tmpfd = mkstemp(ccname + strlen("FILE:")); 255 oerrno = errno; 256 umask(old_umask); 257 if (tmpfd == -1) { 258 logit("mkstemp(): %.100s", strerror(oerrno)); 259 return oerrno; 260 } 261 262 if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) { 263 oerrno = errno; 264 logit("fchmod(): %.100s", strerror(oerrno)); 265 close(tmpfd); 266 return oerrno; 267 } 268 close(tmpfd); 269 270 return (krb5_cc_resolve(ctx, ccname, ccache)); 271 } 272 #endif /* !HEIMDAL */ 273 #endif /* KRB5 */ 274