1 /* 2 * Copyright (c) 1999 - 2001 Kungliga Tekniska H�gskolan 3 * (Royal Institute of Technology, Stockholm, Sweden). 4 * 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 * 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * 3. Neither the name of KTH nor the names of its contributors may be 18 * used to endorse or promote products derived from this software without 19 * specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY KTH AND ITS CONTRIBUTORS ``AS IS'' AND ANY 22 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 24 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL KTH OR ITS CONTRIBUTORS BE 25 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 26 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 27 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR 28 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 29 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 30 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 31 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ 32 33 #include <config.h> 34 35 RCSID("$Id: su.c,v 1.20 2001/02/20 01:44:48 assar Exp $"); 36 37 #include <stdio.h> 38 #include <stdlib.h> 39 #include <string.h> 40 41 #include <syslog.h> 42 43 #ifdef HAVE_PATHS_H 44 #include <paths.h> 45 #endif 46 47 #ifdef HAVE_SHADOW_H 48 #include <shadow.h> 49 #endif 50 51 #include <pwd.h> 52 53 #ifdef HAVE_OPENSSL_DES_H 54 #include <openssl/des.h> 55 #else 56 #include <des.h> 57 #endif 58 #include <krb5.h> 59 #include <kafs.h> 60 #include <err.h> 61 #include <roken.h> 62 #include <getarg.h> 63 #include <kafs.h> 64 65 #ifndef _PATH_DEFPATH 66 #define _PATH_DEFPATH "/usr/bin:/bin" 67 #endif 68 69 #ifndef _PATH_BSHELL 70 #define _PATH_BSHELL "/bin/sh" 71 #endif 72 73 int kerberos_flag = 1; 74 int csh_f_flag; 75 int full_login; 76 int env_flag; 77 char *kerberos_instance = "root"; 78 int help_flag; 79 int version_flag; 80 char *cmd; 81 82 struct getargs args[] = { 83 { "kerberos", 'K', arg_negative_flag, &kerberos_flag, 84 "don't use kerberos" }, 85 { NULL, 'f', arg_flag, &csh_f_flag, 86 "don't read .cshrc" }, 87 { "full", 'l', arg_flag, &full_login, 88 "simulate full login" }, 89 { NULL, 'm', arg_flag, &env_flag, 90 "leave environment unmodified" }, 91 { "instance", 'i', arg_string, &kerberos_instance, 92 "root instance to use" }, 93 { "command", 'c', arg_string, &cmd, 94 "command to execute" }, 95 { "help", 'h', arg_flag, &help_flag }, 96 { "version", 0, arg_flag, &version_flag }, 97 }; 98 99 100 static void 101 usage (int ret) 102 { 103 arg_printusage (args, 104 sizeof(args)/sizeof(*args), 105 NULL, 106 "[login [shell arguments]]"); 107 exit (ret); 108 } 109 110 static struct passwd* 111 make_info(struct passwd *pwd) 112 { 113 struct passwd *info; 114 info = malloc(sizeof(*info)); 115 if(info == NULL) 116 return NULL; 117 info->pw_name = strdup(pwd->pw_name); 118 info->pw_passwd = strdup(pwd->pw_passwd); 119 info->pw_uid = pwd->pw_uid; 120 info->pw_gid = pwd->pw_gid; 121 info->pw_dir = strdup(pwd->pw_dir); 122 info->pw_shell = strdup(pwd->pw_shell); 123 if(info->pw_name == NULL || info->pw_passwd == NULL || 124 info->pw_dir == NULL || info->pw_shell == NULL) 125 return NULL; 126 return info; 127 } 128 129 #ifdef KRB5 130 static krb5_context context; 131 static krb5_ccache ccache; 132 #endif 133 134 static int 135 krb5_verify(struct passwd *login_info, struct passwd *su_info, 136 const char *kerberos_instance) 137 { 138 #ifdef KRB5 139 krb5_error_code ret; 140 krb5_principal p; 141 142 ret = krb5_init_context (&context); 143 if (ret) { 144 #if 0 145 warnx("krb5_init_context failed: %d", ret); 146 #endif 147 return 1; 148 } 149 150 if (strcmp (su_info->pw_name, "root") == 0) 151 ret = krb5_make_principal(context, &p, NULL, 152 login_info->pw_name, 153 kerberos_instance, 154 NULL); 155 else 156 ret = krb5_make_principal(context, &p, NULL, 157 su_info->pw_name, 158 NULL); 159 if(ret) 160 return 1; 161 162 if(su_info->pw_uid != 0 || krb5_kuserok(context, p, su_info->pw_name)) { 163 ret = krb5_cc_gen_new(context, &krb5_mcc_ops, &ccache); 164 if(ret) { 165 #if 1 166 krb5_warn(context, ret, "krb5_cc_gen_new"); 167 #endif 168 krb5_free_principal (context, p); 169 return 1; 170 } 171 ret = krb5_verify_user_lrealm(context, p, ccache, NULL, TRUE, NULL); 172 krb5_free_principal (context, p); 173 if(ret) { 174 krb5_cc_destroy(context, ccache); 175 switch (ret) { 176 case KRB5_LIBOS_PWDINTR : 177 break; 178 case KRB5KRB_AP_ERR_BAD_INTEGRITY: 179 case KRB5KRB_AP_ERR_MODIFIED: 180 krb5_warnx(context, "Password incorrect"); 181 break; 182 default : 183 krb5_warn(context, ret, "krb5_verify_user"); 184 break; 185 } 186 return 1; 187 } 188 return 0; 189 } 190 krb5_free_principal (context, p); 191 #endif 192 return 1; 193 } 194 195 #ifdef KRB5 196 static int 197 krb5_start_session(void) 198 { 199 krb5_ccache ccache2; 200 char *cc_name; 201 int ret; 202 203 ret = krb5_cc_gen_new(context, &krb5_fcc_ops, &ccache2); 204 if (ret) { 205 krb5_cc_destroy(context, ccache); 206 return 1; 207 } 208 209 ret = krb5_cc_copy_cache(context, ccache, ccache2); 210 211 asprintf(&cc_name, "%s:%s", krb5_cc_get_type(context, ccache2), 212 krb5_cc_get_name(context, ccache2)); 213 esetenv("KRB5CCNAME", cc_name, 1); 214 215 /* we want to export this even if we don't directly support KRB4 */ 216 { 217 #ifndef TKT_ROOT 218 #define TKT_ROOT "/tmp/tkt" 219 #endif 220 int fd; 221 char tkfile[256]; 222 strlcpy(tkfile, TKT_ROOT, sizeof(tkfile)); 223 strlcat(tkfile, "_XXXXXX", sizeof(tkfile)); 224 fd = mkstemp(tkfile); 225 if(fd >= 0) { 226 close(fd); 227 esetenv("KRBTKFILE", tkfile, 1); 228 } 229 } 230 231 #ifdef KRB4 232 /* convert creds? */ 233 if(k_hasafs()) { 234 if (k_setpag() == 0) 235 krb5_afslog(context, ccache2, NULL, NULL); 236 } 237 #endif 238 239 krb5_cc_close(context, ccache2); 240 krb5_cc_destroy(context, ccache); 241 return 0; 242 } 243 #endif 244 245 static int 246 verify_unix(struct passwd *su) 247 { 248 char prompt[128]; 249 char pw_buf[1024]; 250 char *pw; 251 int r; 252 if(su->pw_passwd != NULL && *su->pw_passwd != '\0') { 253 snprintf(prompt, sizeof(prompt), "%s's password: ", su->pw_name); 254 r = des_read_pw_string(pw_buf, sizeof(pw_buf), prompt, 0); 255 if(r != 0) 256 exit(0); 257 pw = crypt(pw_buf, su->pw_passwd); 258 memset(pw_buf, 0, sizeof(pw_buf)); 259 if(strcmp(pw, su->pw_passwd) != 0) 260 return 1; 261 } 262 return 0; 263 } 264 265 int 266 main(int argc, char **argv) 267 { 268 int i, optind = 0; 269 char *su_user; 270 struct passwd *su_info; 271 char *login_user = NULL; 272 struct passwd *login_info; 273 274 struct passwd *pwd; 275 276 char *shell; 277 278 int ok = 0; 279 int kerberos_error=1; 280 281 setprogname (argv[0]); 282 283 if(getarg(args, sizeof(args) / sizeof(args[0]), argc, argv, &optind)) 284 usage(1); 285 286 for (i=0; i < optind; i++) 287 if (strcmp(argv[i], "-") == 0) { 288 full_login = 1; 289 break; 290 } 291 292 if(help_flag) 293 usage(0); 294 if(version_flag) { 295 print_version(NULL); 296 exit(0); 297 } 298 if(optind >= argc) 299 su_user = "root"; 300 else 301 su_user = argv[optind++]; 302 303 pwd = k_getpwnam(su_user); 304 if(pwd == NULL) 305 errx (1, "unknown login %s", su_user); 306 if (pwd->pw_uid == 0 && strcmp ("root", su_user) != 0) { 307 syslog (LOG_ALERT, "NIS attack, user %s has uid 0", su_user); 308 errx (1, "unknown login %s", su_user); 309 } 310 su_info = make_info(pwd); 311 312 #if defined(HAVE_GETLOGIN) && !defined(POSIX_GETLOGIN) 313 login_user = getlogin(); 314 #endif 315 if(login_user == NULL || (pwd = getpwnam(login_user)) == NULL) 316 pwd = getpwuid(getuid()); 317 if(pwd == NULL) 318 errx(1, "who are you?"); 319 login_info = make_info(pwd); 320 if(env_flag) 321 shell = login_info->pw_shell; 322 else 323 shell = su_info->pw_shell; 324 if(shell == NULL || *shell == '\0') 325 shell = _PATH_BSHELL; 326 327 if(kerberos_flag && ok == 0 && 328 (kerberos_error=krb5_verify(login_info, su_info, kerberos_instance)) == 0) 329 ok++; 330 331 if(ok == 0 && login_info->pw_uid && verify_unix(su_info) != 0) { 332 printf("Sorry!\n"); 333 exit(1); 334 } 335 336 #ifdef HAVE_GETSPNAM 337 { struct spwd *sp; 338 long today; 339 340 sp = getspnam(su_info->pw_name); 341 if (sp != NULL) { 342 today = time(0)/(24L * 60 * 60); 343 if (sp->sp_expire > 0) { 344 if (today >= sp->sp_expire) { 345 if (login_info->pw_uid) 346 errx(1,"Your account has expired."); 347 else 348 printf("Your account has expired."); 349 } 350 else if (sp->sp_expire - today < 14) 351 printf("Your account will expire in %d days.\n", 352 (int)(sp->sp_expire - today)); 353 } 354 if (sp->sp_max > 0) { 355 if (today >= sp->sp_lstchg + sp->sp_max) { 356 if (login_info->pw_uid) 357 errx(1,"Your password has expired. Choose a new one."); 358 else 359 printf("Your password has expired. Choose a new one."); 360 } 361 else if (today >= sp->sp_lstchg + sp->sp_max - sp->sp_warn) 362 printf("Your account will expire in %d days.\n", 363 (int)(sp->sp_lstchg + sp->sp_max -today)); 364 } 365 } 366 } 367 #endif 368 { 369 char *tty = ttyname (STDERR_FILENO); 370 syslog (LOG_NOTICE | LOG_AUTH, tty ? "%s to %s" : "%s to %s on %s", 371 login_info->pw_name, su_info->pw_name, tty); 372 } 373 374 375 if(!env_flag) { 376 if(full_login) { 377 char *t = getenv ("TERM"); 378 379 environ = malloc (10 * sizeof (char *)); 380 if (environ == NULL) 381 err (1, "malloc"); 382 environ[0] = NULL; 383 esetenv ("PATH", _PATH_DEFPATH, 1); 384 if (t) 385 esetenv ("TERM", t, 1); 386 if (chdir (su_info->pw_dir) < 0) 387 errx (1, "no directory"); 388 } 389 if (full_login || su_info->pw_uid) 390 esetenv ("USER", su_info->pw_name, 1); 391 esetenv("HOME", su_info->pw_dir, 1); 392 esetenv("SHELL", shell, 1); 393 } 394 395 { 396 int i; 397 char **args; 398 char *p; 399 400 p = strrchr(shell, '/'); 401 if(p) 402 p++; 403 else 404 p = shell; 405 406 if (strcmp(p, "csh") != 0) 407 csh_f_flag = 0; 408 409 args = malloc(((cmd ? 2 : 0) + 1 + argc - optind + 1 + csh_f_flag) * sizeof(*args)); 410 if (args == NULL) 411 err (1, "malloc"); 412 i = 0; 413 if(full_login) 414 asprintf(&args[i++], "-%s", p); 415 else 416 args[i++] = p; 417 if (cmd) { 418 args[i++] = "-c"; 419 args[i++] = cmd; 420 } 421 422 if (csh_f_flag) 423 args[i++] = "-f"; 424 425 for (argv += optind; *argv; ++argv) 426 args[i++] = *argv; 427 args[i] = NULL; 428 429 if(setgid(su_info->pw_gid) < 0) 430 err(1, "setgid"); 431 if (initgroups (su_info->pw_name, su_info->pw_gid) < 0) 432 err (1, "initgroups"); 433 if(setuid(su_info->pw_uid) < 0 434 || (su_info->pw_uid != 0 && setuid(0) == 0)) 435 err(1, "setuid"); 436 437 #ifdef KRB5 438 if (!kerberos_error) 439 krb5_start_session(); 440 #endif 441 execv(shell, args); 442 } 443 444 exit(1); 445 } 446