1/* Licensed to the Apache Software Foundation (ASF) under one or more 2 * contributor license agreements. See the NOTICE file distributed with 3 * this work for additional information regarding copyright ownership. 4 * The ASF licenses this file to You under the Apache License, Version 2.0 5 * (the "License"); you may not use this file except in compliance with 6 * the License. You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17/* 18 * suexec.c -- "Wrapper" support program for suEXEC behaviour for Apache 19 * 20 *********************************************************************** 21 * 22 * NOTE! : DO NOT edit this code!!! Unless you know what you are doing, 23 * editing this code might open up your system in unexpected 24 * ways to would-be crackers. Every precaution has been taken 25 * to make this code as safe as possible; alter it at your own 26 * risk. 27 * 28 *********************************************************************** 29 * 30 * 31 */ 32 33#include "apr.h" 34#include "ap_config.h" 35#include "suexec.h" 36 37#include <sys/param.h> 38#include <sys/stat.h> 39#include <sys/types.h> 40#include <string.h> 41#include <time.h> 42#if APR_HAVE_UNISTD_H 43#include <unistd.h> 44#endif 45 46#include <stdio.h> 47#include <stdarg.h> 48#include <stdlib.h> 49 50#ifdef HAVE_PWD_H 51#include <pwd.h> 52#endif 53 54#ifdef HAVE_GRP_H 55#include <grp.h> 56#endif 57 58/* 59 *********************************************************************** 60 * There is no initgroups() in QNX, so I believe this is safe :-) 61 * Use cc -osuexec -3 -O -mf -DQNX suexec.c to compile. 62 * 63 * May 17, 1997. 64 * Igor N. Kovalenko -- infoh mail.wplus.net 65 *********************************************************************** 66 */ 67 68#if defined(NEED_INITGROUPS) 69int initgroups(const char *name, gid_t basegid) 70{ 71 /* QNX and MPE do not appear to support supplementary groups. */ 72 return 0; 73} 74#endif 75 76#if defined(SUNOS4) 77extern char *sys_errlist[]; 78#define strerror(x) sys_errlist[(x)] 79#endif 80 81#if defined(PATH_MAX) 82#define AP_MAXPATH PATH_MAX 83#elif defined(MAXPATHLEN) 84#define AP_MAXPATH MAXPATHLEN 85#else 86#define AP_MAXPATH 8192 87#endif 88 89#define AP_ENVBUF 256 90 91extern char **environ; 92static FILE *log = NULL; 93 94static const char *const safe_env_lst[] = 95{ 96 /* variable name starts with */ 97 "HTTP_", 98 "SSL_", 99 100 /* variable name is */ 101 "AUTH_TYPE=", 102 "CONTENT_LENGTH=", 103 "CONTENT_TYPE=", 104 "DATE_GMT=", 105 "DATE_LOCAL=", 106 "DOCUMENT_NAME=", 107 "DOCUMENT_PATH_INFO=", 108 "DOCUMENT_ROOT=", 109 "DOCUMENT_URI=", 110 "GATEWAY_INTERFACE=", 111 "HTTPS=", 112 "LAST_MODIFIED=", 113 "PATH_INFO=", 114 "PATH_TRANSLATED=", 115 "QUERY_STRING=", 116 "QUERY_STRING_UNESCAPED=", 117 "REMOTE_ADDR=", 118 "REMOTE_HOST=", 119 "REMOTE_IDENT=", 120 "REMOTE_PORT=", 121 "REMOTE_USER=", 122 "REDIRECT_HANDLER=", 123 "REDIRECT_QUERY_STRING=", 124 "REDIRECT_REMOTE_USER=", 125 "REDIRECT_STATUS=", 126 "REDIRECT_URL=", 127 "REQUEST_METHOD=", 128 "REQUEST_URI=", 129 "SCRIPT_FILENAME=", 130 "SCRIPT_NAME=", 131 "SCRIPT_URI=", 132 "SCRIPT_URL=", 133 "SERVER_ADMIN=", 134 "SERVER_NAME=", 135 "SERVER_ADDR=", 136 "SERVER_PORT=", 137 "SERVER_PROTOCOL=", 138 "SERVER_SIGNATURE=", 139 "SERVER_SOFTWARE=", 140 "UNIQUE_ID=", 141 "USER_NAME=", 142 "TZ=", 143 NULL 144}; 145 146 147static void err_output(int is_error, const char *fmt, va_list ap) 148{ 149#ifdef AP_LOG_EXEC 150 time_t timevar; 151 struct tm *lt; 152 153 if (!log) { 154 if ((log = fopen(AP_LOG_EXEC, "a")) == NULL) { 155 fprintf(stderr, "suexec failure: could not open log file\n"); 156 perror("fopen"); 157 exit(1); 158 } 159 } 160 161 if (is_error) { 162 fprintf(stderr, "suexec policy violation: see suexec log for more " 163 "details\n"); 164 } 165 166 time(&timevar); 167 lt = localtime(&timevar); 168 169 fprintf(log, "[%d-%.2d-%.2d %.2d:%.2d:%.2d]: ", 170 lt->tm_year + 1900, lt->tm_mon + 1, lt->tm_mday, 171 lt->tm_hour, lt->tm_min, lt->tm_sec); 172 173 vfprintf(log, fmt, ap); 174 175 fflush(log); 176#endif /* AP_LOG_EXEC */ 177 return; 178} 179 180static void log_err(const char *fmt,...) 181{ 182#ifdef AP_LOG_EXEC 183 va_list ap; 184 185 va_start(ap, fmt); 186 err_output(1, fmt, ap); /* 1 == is_error */ 187 va_end(ap); 188#endif /* AP_LOG_EXEC */ 189 return; 190} 191 192static void log_no_err(const char *fmt,...) 193{ 194#ifdef AP_LOG_EXEC 195 va_list ap; 196 197 va_start(ap, fmt); 198 err_output(0, fmt, ap); /* 0 == !is_error */ 199 va_end(ap); 200#endif /* AP_LOG_EXEC */ 201 return; 202} 203 204static void clean_env(void) 205{ 206 char pathbuf[512]; 207 char **cleanenv; 208 char **ep; 209 int cidx = 0; 210 int idx; 211 212 /* While cleaning the environment, the environment should be clean. 213 * (e.g. malloc() may get the name of a file for writing debugging info. 214 * Bad news if MALLOC_DEBUG_FILE is set to /etc/passwd. Sprintf() may be 215 * susceptible to bad locale settings....) 216 * (from PR 2790) 217 */ 218 char **envp = environ; 219 char *empty_ptr = NULL; 220 221 environ = &empty_ptr; /* VERY safe environment */ 222 223 if ((cleanenv = (char **) calloc(AP_ENVBUF, sizeof(char *))) == NULL) { 224 log_err("failed to malloc memory for environment\n"); 225 exit(120); 226 } 227 228 sprintf(pathbuf, "PATH=%s", AP_SAFE_PATH); 229 cleanenv[cidx] = strdup(pathbuf); 230 cidx++; 231 232 for (ep = envp; *ep && cidx < AP_ENVBUF-1; ep++) { 233 for (idx = 0; safe_env_lst[idx]; idx++) { 234 if (!strncmp(*ep, safe_env_lst[idx], 235 strlen(safe_env_lst[idx]))) { 236 cleanenv[cidx] = *ep; 237 cidx++; 238 break; 239 } 240 } 241 } 242 243 cleanenv[cidx] = NULL; 244 245 environ = cleanenv; 246} 247 248int main(int argc, char *argv[]) 249{ 250 int userdir = 0; /* ~userdir flag */ 251 uid_t uid; /* user information */ 252 gid_t gid; /* target group placeholder */ 253 char *target_uname; /* target user name */ 254 char *target_gname; /* target group name */ 255 char *target_homedir; /* target home directory */ 256 char *actual_uname; /* actual user name */ 257 char *actual_gname; /* actual group name */ 258 char *prog; /* name of this program */ 259 char *cmd; /* command to be executed */ 260 char cwd[AP_MAXPATH]; /* current working directory */ 261 char dwd[AP_MAXPATH]; /* docroot working directory */ 262 struct passwd *pw; /* password entry holder */ 263 struct group *gr; /* group entry holder */ 264 struct stat dir_info; /* directory info holder */ 265 struct stat prg_info; /* program info holder */ 266 267 /* 268 * Start with a "clean" environment 269 */ 270 clean_env(); 271 272 prog = argv[0]; 273 /* 274 * Check existence/validity of the UID of the user 275 * running this program. Error out if invalid. 276 */ 277 uid = getuid(); 278 if ((pw = getpwuid(uid)) == NULL) { 279 log_err("crit: invalid uid: (%ld)\n", uid); 280 exit(102); 281 } 282 /* 283 * See if this is a 'how were you compiled' request, and 284 * comply if so. 285 */ 286 if ((argc > 1) 287 && (! strcmp(argv[1], "-V")) 288 && ((uid == 0) 289#ifdef _OSD_POSIX 290 /* User name comparisons are case insensitive on BS2000/OSD */ 291 || (! strcasecmp(AP_HTTPD_USER, pw->pw_name))) 292#else /* _OSD_POSIX */ 293 || (! strcmp(AP_HTTPD_USER, pw->pw_name))) 294#endif /* _OSD_POSIX */ 295 ) { 296#ifdef AP_DOC_ROOT 297 fprintf(stderr, " -D AP_DOC_ROOT=\"%s\"\n", AP_DOC_ROOT); 298#endif 299#ifdef AP_GID_MIN 300 fprintf(stderr, " -D AP_GID_MIN=%d\n", AP_GID_MIN); 301#endif 302#ifdef AP_HTTPD_USER 303 fprintf(stderr, " -D AP_HTTPD_USER=\"%s\"\n", AP_HTTPD_USER); 304#endif 305#ifdef AP_LOG_EXEC 306 fprintf(stderr, " -D AP_LOG_EXEC=\"%s\"\n", AP_LOG_EXEC); 307#endif 308#ifdef AP_SAFE_PATH 309 fprintf(stderr, " -D AP_SAFE_PATH=\"%s\"\n", AP_SAFE_PATH); 310#endif 311#ifdef AP_SUEXEC_UMASK 312 fprintf(stderr, " -D AP_SUEXEC_UMASK=%03o\n", AP_SUEXEC_UMASK); 313#endif 314#ifdef AP_UID_MIN 315 fprintf(stderr, " -D AP_UID_MIN=%d\n", AP_UID_MIN); 316#endif 317#ifdef AP_USERDIR_SUFFIX 318 fprintf(stderr, " -D AP_USERDIR_SUFFIX=\"%s\"\n", AP_USERDIR_SUFFIX); 319#endif 320 exit(0); 321 } 322 /* 323 * If there are a proper number of arguments, set 324 * all of them to variables. Otherwise, error out. 325 */ 326 if (argc < 4) { 327 log_err("too few arguments\n"); 328 exit(101); 329 } 330 target_uname = argv[1]; 331 target_gname = argv[2]; 332 cmd = argv[3]; 333 334 /* 335 * Check to see if the user running this program 336 * is the user allowed to do so as defined in 337 * suexec.h. If not the allowed user, error out. 338 */ 339#ifdef _OSD_POSIX 340 /* User name comparisons are case insensitive on BS2000/OSD */ 341 if (strcasecmp(AP_HTTPD_USER, pw->pw_name)) { 342 log_err("user mismatch (%s instead of %s)\n", pw->pw_name, AP_HTTPD_USER); 343 exit(103); 344 } 345#else /*_OSD_POSIX*/ 346 if (strcmp(AP_HTTPD_USER, pw->pw_name)) { 347 log_err("user mismatch (%s instead of %s)\n", pw->pw_name, AP_HTTPD_USER); 348 exit(103); 349 } 350#endif /*_OSD_POSIX*/ 351 352 /* 353 * Check for a leading '/' (absolute path) in the command to be executed, 354 * or attempts to back up out of the current directory, 355 * to protect against attacks. If any are 356 * found, error out. Naughty naughty crackers. 357 */ 358 if ((cmd[0] == '/') || (!strncmp(cmd, "../", 3)) 359 || (strstr(cmd, "/../") != NULL)) { 360 log_err("invalid command (%s)\n", cmd); 361 exit(104); 362 } 363 364 /* 365 * Check to see if this is a ~userdir request. If 366 * so, set the flag, and remove the '~' from the 367 * target username. 368 */ 369 if (!strncmp("~", target_uname, 1)) { 370 target_uname++; 371 userdir = 1; 372 } 373 374 /* 375 * Error out if the target username is invalid. 376 */ 377 if (strspn(target_uname, "1234567890") != strlen(target_uname)) { 378 if ((pw = getpwnam(target_uname)) == NULL) { 379 log_err("invalid target user name: (%s)\n", target_uname); 380 exit(105); 381 } 382 } 383 else { 384 if ((pw = getpwuid(atoi(target_uname))) == NULL) { 385 log_err("invalid target user id: (%s)\n", target_uname); 386 exit(121); 387 } 388 } 389 390 /* 391 * Error out if the target group name is invalid. 392 */ 393 if (strspn(target_gname, "1234567890") != strlen(target_gname)) { 394 if ((gr = getgrnam(target_gname)) == NULL) { 395 log_err("invalid target group name: (%s)\n", target_gname); 396 exit(106); 397 } 398 } 399 else { 400 if ((gr = getgrgid(atoi(target_gname))) == NULL) { 401 log_err("invalid target group id: (%s)\n", target_gname); 402 exit(106); 403 } 404 } 405 gid = gr->gr_gid; 406 actual_gname = strdup(gr->gr_name); 407 408#ifdef _OSD_POSIX 409 /* 410 * Initialize BS2000 user environment 411 */ 412 { 413 pid_t pid; 414 int status; 415 416 switch (pid = ufork(target_uname)) { 417 case -1: /* Error */ 418 log_err("failed to setup bs2000 environment for user %s: %s\n", 419 target_uname, strerror(errno)); 420 exit(150); 421 case 0: /* Child */ 422 break; 423 default: /* Father */ 424 while (pid != waitpid(pid, &status, 0)) 425 ; 426 /* @@@ FIXME: should we deal with STOP signals as well? */ 427 if (WIFSIGNALED(status)) { 428 kill (getpid(), WTERMSIG(status)); 429 } 430 exit(WEXITSTATUS(status)); 431 } 432 } 433#endif /*_OSD_POSIX*/ 434 435 /* 436 * Save these for later since initgroups will hose the struct 437 */ 438 uid = pw->pw_uid; 439 actual_uname = strdup(pw->pw_name); 440 target_homedir = strdup(pw->pw_dir); 441 442 /* 443 * Log the transaction here to be sure we have an open log 444 * before we setuid(). 445 */ 446 log_no_err("uid: (%s/%s) gid: (%s/%s) cmd: %s\n", 447 target_uname, actual_uname, 448 target_gname, actual_gname, 449 cmd); 450 451 /* 452 * Error out if attempt is made to execute as root or as 453 * a UID less than AP_UID_MIN. Tsk tsk. 454 */ 455 if ((uid == 0) || (uid < AP_UID_MIN)) { 456 log_err("cannot run as forbidden uid (%d/%s)\n", uid, cmd); 457 exit(107); 458 } 459 460 /* 461 * Error out if attempt is made to execute as root group 462 * or as a GID less than AP_GID_MIN. Tsk tsk. 463 */ 464 if ((gid == 0) || (gid < AP_GID_MIN)) { 465 log_err("cannot run as forbidden gid (%d/%s)\n", gid, cmd); 466 exit(108); 467 } 468 469 /* 470 * Change UID/GID here so that the following tests work over NFS. 471 * 472 * Initialize the group access list for the target user, 473 * and setgid() to the target group. If unsuccessful, error out. 474 */ 475 if (((setgid(gid)) != 0) || (initgroups(actual_uname, gid) != 0)) { 476 log_err("failed to setgid (%ld: %s)\n", gid, cmd); 477 exit(109); 478 } 479 480 /* 481 * setuid() to the target user. Error out on fail. 482 */ 483 if ((setuid(uid)) != 0) { 484 log_err("failed to setuid (%ld: %s)\n", uid, cmd); 485 exit(110); 486 } 487 488 /* 489 * Get the current working directory, as well as the proper 490 * document root (dependant upon whether or not it is a 491 * ~userdir request). Error out if we cannot get either one, 492 * or if the current working directory is not in the docroot. 493 * Use chdir()s and getcwd()s to avoid problems with symlinked 494 * directories. Yuck. 495 */ 496 if (getcwd(cwd, AP_MAXPATH) == NULL) { 497 log_err("cannot get current working directory\n"); 498 exit(111); 499 } 500 501 if (userdir) { 502 if (((chdir(target_homedir)) != 0) || 503 ((chdir(AP_USERDIR_SUFFIX)) != 0) || 504 ((getcwd(dwd, AP_MAXPATH)) == NULL) || 505 ((chdir(cwd)) != 0)) { 506 log_err("cannot get docroot information (%s)\n", target_homedir); 507 exit(112); 508 } 509 } 510 else { 511 if (((chdir(AP_DOC_ROOT)) != 0) || 512 ((getcwd(dwd, AP_MAXPATH)) == NULL) || 513 ((chdir(cwd)) != 0)) { 514 log_err("cannot get docroot information (%s)\n", AP_DOC_ROOT); 515 exit(113); 516 } 517 } 518 519 if ((strncmp(cwd, dwd, strlen(dwd))) != 0) { 520 log_err("command not in docroot (%s/%s)\n", cwd, cmd); 521 exit(114); 522 } 523 524 /* 525 * Stat the cwd and verify it is a directory, or error out. 526 */ 527 if (((lstat(cwd, &dir_info)) != 0) || !(S_ISDIR(dir_info.st_mode))) { 528 log_err("cannot stat directory: (%s)\n", cwd); 529 exit(115); 530 } 531 532 /* 533 * Error out if cwd is writable by others. 534 */ 535 if ((dir_info.st_mode & S_IWOTH) || (dir_info.st_mode & S_IWGRP)) { 536 log_err("directory is writable by others: (%s)\n", cwd); 537 exit(116); 538 } 539 540 /* 541 * Error out if we cannot stat the program. 542 */ 543 if (((lstat(cmd, &prg_info)) != 0) || (S_ISLNK(prg_info.st_mode))) { 544 log_err("cannot stat program: (%s)\n", cmd); 545 exit(117); 546 } 547 548 /* 549 * Error out if the program is writable by others. 550 */ 551 if ((prg_info.st_mode & S_IWOTH) || (prg_info.st_mode & S_IWGRP)) { 552 log_err("file is writable by others: (%s/%s)\n", cwd, cmd); 553 exit(118); 554 } 555 556 /* 557 * Error out if the file is setuid or setgid. 558 */ 559 if ((prg_info.st_mode & S_ISUID) || (prg_info.st_mode & S_ISGID)) { 560 log_err("file is either setuid or setgid: (%s/%s)\n", cwd, cmd); 561 exit(119); 562 } 563 564 /* 565 * Error out if the target name/group is different from 566 * the name/group of the cwd or the program. 567 */ 568 if ((uid != dir_info.st_uid) || 569 (gid != dir_info.st_gid) || 570 (uid != prg_info.st_uid) || 571 (gid != prg_info.st_gid)) { 572 log_err("target uid/gid (%ld/%ld) mismatch " 573 "with directory (%ld/%ld) or program (%ld/%ld)\n", 574 uid, gid, 575 dir_info.st_uid, dir_info.st_gid, 576 prg_info.st_uid, prg_info.st_gid); 577 exit(120); 578 } 579 /* 580 * Error out if the program is not executable for the user. 581 * Otherwise, she won't find any error in the logs except for 582 * "[error] Premature end of script headers: ..." 583 */ 584 if (!(prg_info.st_mode & S_IXUSR)) { 585 log_err("file has no execute permission: (%s/%s)\n", cwd, cmd); 586 exit(121); 587 } 588 589#ifdef AP_SUEXEC_UMASK 590 /* 591 * umask() uses inverse logic; bits are CLEAR for allowed access. 592 */ 593 if ((~AP_SUEXEC_UMASK) & 0022) { 594 log_err("notice: AP_SUEXEC_UMASK of %03o allows " 595 "write permission to group and/or other\n", AP_SUEXEC_UMASK); 596 } 597 umask(AP_SUEXEC_UMASK); 598#endif /* AP_SUEXEC_UMASK */ 599 600 /* 601 * Be sure to close the log file so the CGI can't 602 * mess with it. If the exec fails, it will be reopened 603 * automatically when log_err is called. Note that the log 604 * might not actually be open if AP_LOG_EXEC isn't defined. 605 * However, the "log" cell isn't ifdef'd so let's be defensive 606 * and assume someone might have done something with it 607 * outside an ifdef'd AP_LOG_EXEC block. 608 */ 609 if (log != NULL) { 610 fclose(log); 611 log = NULL; 612 } 613 614 /* 615 * Execute the command, replacing our image with its own. 616 */ 617#ifdef NEED_HASHBANG_EMUL 618 /* We need the #! emulation when we want to execute scripts */ 619 { 620 extern char **environ; 621 622 ap_execve(cmd, &argv[3], environ); 623 } 624#else /*NEED_HASHBANG_EMUL*/ 625 execv(cmd, &argv[3]); 626#endif /*NEED_HASHBANG_EMUL*/ 627 628 /* 629 * (I can't help myself...sorry.) 630 * 631 * Uh oh. Still here. Where's the kaboom? There was supposed to be an 632 * EARTH-shattering kaboom! 633 * 634 * Oh well, log the failure and error out. 635 */ 636 log_err("(%d)%s: exec failed (%s)\n", errno, strerror(errno), cmd); 637 exit(255); 638} 639