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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
18 * suexec.c -- "Wrapper" support program for suEXEC behaviour for Apache
20 ***********************************************************************
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
28 ***********************************************************************
34 #include "ap_config.h"
37 #include <sys/param.h>
39 #include <sys/types.h>
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.
64 * Igor N. Kovalenko -- infoh@mail.wplus.net
65 ***********************************************************************
68 #if defined(NEED_INITGROUPS)
69 int initgroups(const char *name, gid_t basegid)
71 /* QNX and MPE do not appear to support supplementary groups. */
77 extern char *sys_errlist[];
78 #define strerror(x) sys_errlist[(x)]
82 #define AP_MAXPATH PATH_MAX
83 #elif defined(MAXPATHLEN)
84 #define AP_MAXPATH MAXPATHLEN
86 #define AP_MAXPATH 8192
91 extern char **environ;
92 static FILE *log = NULL;
94 char *safe_env_lst[] =
96 /* variable name starts with */
100 /* variable name is */
107 "DOCUMENT_PATH_INFO=",
111 "GATEWAY_INTERFACE=",
117 "QUERY_STRING_UNESCAPED=",
123 "REDIRECT_QUERY_STRING=",
124 "REDIRECT_REMOTE_USER=",
147 static void err_output(const char *fmt, va_list ap)
154 if ((log = fopen(AP_LOG_EXEC, "a")) == NULL) {
155 fprintf(stderr, "failed to open log file\n");
162 lt = localtime(&timevar);
164 fprintf(log, "[%d-%.2d-%.2d %.2d:%.2d:%.2d]: ",
165 lt->tm_year + 1900, lt->tm_mon + 1, lt->tm_mday,
166 lt->tm_hour, lt->tm_min, lt->tm_sec);
168 vfprintf(log, fmt, ap);
171 #endif /* AP_LOG_EXEC */
175 static void log_err(const char *fmt,...)
183 #endif /* AP_LOG_EXEC */
187 static void clean_env(void)
195 /* While cleaning the environment, the environment should be clean.
196 * (e.g. malloc() may get the name of a file for writing debugging info.
197 * Bad news if MALLOC_DEBUG_FILE is set to /etc/passwd. Sprintf() may be
198 * susceptible to bad locale settings....)
201 char **envp = environ;
202 char *empty_ptr = NULL;
204 environ = &empty_ptr; /* VERY safe environment */
206 if ((cleanenv = (char **) calloc(AP_ENVBUF, sizeof(char *))) == NULL) {
207 log_err("failed to malloc memory for environment\n");
211 sprintf(pathbuf, "PATH=%s", AP_SAFE_PATH);
212 cleanenv[cidx] = strdup(pathbuf);
215 for (ep = envp; *ep && cidx < AP_ENVBUF-1; ep++) {
216 for (idx = 0; safe_env_lst[idx]; idx++) {
217 if (!strncmp(*ep, safe_env_lst[idx],
218 strlen(safe_env_lst[idx]))) {
219 cleanenv[cidx] = *ep;
226 cleanenv[cidx] = NULL;
231 int main(int argc, char *argv[])
233 int userdir = 0; /* ~userdir flag */
234 uid_t uid; /* user information */
235 gid_t gid; /* target group placeholder */
236 char *target_uname; /* target user name */
237 char *target_gname; /* target group name */
238 char *target_homedir; /* target home directory */
239 char *actual_uname; /* actual user name */
240 char *actual_gname; /* actual group name */
241 char *prog; /* name of this program */
242 char *cmd; /* command to be executed */
243 char cwd[AP_MAXPATH]; /* current working directory */
244 char dwd[AP_MAXPATH]; /* docroot working directory */
245 struct passwd *pw; /* password entry holder */
246 struct group *gr; /* group entry holder */
247 struct stat dir_info; /* directory info holder */
248 struct stat prg_info; /* program info holder */
251 * Start with a "clean" environment
257 * Check existence/validity of the UID of the user
258 * running this program. Error out if invalid.
261 if ((pw = getpwuid(uid)) == NULL) {
262 log_err("crit: invalid uid: (%ld)\n", uid);
266 * See if this is a 'how were you compiled' request, and
270 && (! strcmp(argv[1], "-V"))
273 /* User name comparisons are case insensitive on BS2000/OSD */
274 || (! strcasecmp(AP_HTTPD_USER, pw->pw_name)))
275 #else /* _OSD_POSIX */
276 || (! strcmp(AP_HTTPD_USER, pw->pw_name)))
277 #endif /* _OSD_POSIX */
280 fprintf(stderr, " -D AP_DOC_ROOT=\"%s\"\n", AP_DOC_ROOT);
283 fprintf(stderr, " -D AP_GID_MIN=%d\n", AP_GID_MIN);
286 fprintf(stderr, " -D AP_HTTPD_USER=\"%s\"\n", AP_HTTPD_USER);
289 fprintf(stderr, " -D AP_LOG_EXEC=\"%s\"\n", AP_LOG_EXEC);
292 fprintf(stderr, " -D AP_SAFE_PATH=\"%s\"\n", AP_SAFE_PATH);
294 #ifdef AP_SUEXEC_UMASK
295 fprintf(stderr, " -D AP_SUEXEC_UMASK=%03o\n", AP_SUEXEC_UMASK);
298 fprintf(stderr, " -D AP_UID_MIN=%d\n", AP_UID_MIN);
300 #ifdef AP_USERDIR_SUFFIX
301 fprintf(stderr, " -D AP_USERDIR_SUFFIX=\"%s\"\n", AP_USERDIR_SUFFIX);
306 * If there are a proper number of arguments, set
307 * all of them to variables. Otherwise, error out.
310 log_err("too few arguments\n");
313 target_uname = argv[1];
314 target_gname = argv[2];
318 * Check to see if the user running this program
319 * is the user allowed to do so as defined in
320 * suexec.h. If not the allowed user, error out.
323 /* User name comparisons are case insensitive on BS2000/OSD */
324 if (strcasecmp(AP_HTTPD_USER, pw->pw_name)) {
325 log_err("user mismatch (%s instead of %s)\n", pw->pw_name, AP_HTTPD_USER);
329 if (strcmp(AP_HTTPD_USER, pw->pw_name)) {
330 log_err("user mismatch (%s instead of %s)\n", pw->pw_name, AP_HTTPD_USER);
333 #endif /*_OSD_POSIX*/
336 * Check for a leading '/' (absolute path) in the command to be executed,
337 * or attempts to back up out of the current directory,
338 * to protect against attacks. If any are
339 * found, error out. Naughty naughty crackers.
341 if ((cmd[0] == '/') || (!strncmp(cmd, "../", 3))
342 || (strstr(cmd, "/../") != NULL)) {
343 log_err("invalid command (%s)\n", cmd);
348 * Check to see if this is a ~userdir request. If
349 * so, set the flag, and remove the '~' from the
352 if (!strncmp("~", target_uname, 1)) {
358 * Error out if the target username is invalid.
360 if (strspn(target_uname, "1234567890") != strlen(target_uname)) {
361 if ((pw = getpwnam(target_uname)) == NULL) {
362 log_err("invalid target user name: (%s)\n", target_uname);
367 if ((pw = getpwuid(atoi(target_uname))) == NULL) {
368 log_err("invalid target user id: (%s)\n", target_uname);
374 * Error out if the target group name is invalid.
376 if (strspn(target_gname, "1234567890") != strlen(target_gname)) {
377 if ((gr = getgrnam(target_gname)) == NULL) {
378 log_err("invalid target group name: (%s)\n", target_gname);
382 actual_gname = strdup(gr->gr_name);
385 gid = atoi(target_gname);
386 actual_gname = strdup(target_gname);
391 * Initialize BS2000 user environment
397 switch (pid = ufork(target_uname)) {
399 log_err("failed to setup bs2000 environment for user %s: %s\n",
400 target_uname, strerror(errno));
404 default: /* Father */
405 while (pid != waitpid(pid, &status, 0))
407 /* @@@ FIXME: should we deal with STOP signals as well? */
408 if (WIFSIGNALED(status)) {
409 kill (getpid(), WTERMSIG(status));
411 exit(WEXITSTATUS(status));
414 #endif /*_OSD_POSIX*/
417 * Save these for later since initgroups will hose the struct
420 actual_uname = strdup(pw->pw_name);
421 target_homedir = strdup(pw->pw_dir);
424 * Log the transaction here to be sure we have an open log
425 * before we setuid().
427 log_err("uid: (%s/%s) gid: (%s/%s) cmd: %s\n",
428 target_uname, actual_uname,
429 target_gname, actual_gname,
433 * Error out if attempt is made to execute as root or as
434 * a UID less than AP_UID_MIN. Tsk tsk.
436 if ((uid == 0) || (uid < AP_UID_MIN)) {
437 log_err("cannot run as forbidden uid (%d/%s)\n", uid, cmd);
442 * Error out if attempt is made to execute as root group
443 * or as a GID less than AP_GID_MIN. Tsk tsk.
445 if ((gid == 0) || (gid < AP_GID_MIN)) {
446 log_err("cannot run as forbidden gid (%d/%s)\n", gid, cmd);
451 * Change UID/GID here so that the following tests work over NFS.
453 * Initialize the group access list for the target user,
454 * and setgid() to the target group. If unsuccessful, error out.
456 if (((setgid(gid)) != 0) || (initgroups(actual_uname, gid) != 0)) {
457 log_err("failed to setgid (%ld: %s)\n", gid, cmd);
462 * setuid() to the target user. Error out on fail.
464 if ((setuid(uid)) != 0) {
465 log_err("failed to setuid (%ld: %s)\n", uid, cmd);
470 * Get the current working directory, as well as the proper
471 * document root (dependant upon whether or not it is a
472 * ~userdir request). Error out if we cannot get either one,
473 * or if the current working directory is not in the docroot.
474 * Use chdir()s and getcwd()s to avoid problems with symlinked
477 if (getcwd(cwd, AP_MAXPATH) == NULL) {
478 log_err("cannot get current working directory\n");
483 if (((chdir(target_homedir)) != 0) ||
484 ((chdir(AP_USERDIR_SUFFIX)) != 0) ||
485 ((getcwd(dwd, AP_MAXPATH)) == NULL) ||
486 ((chdir(cwd)) != 0)) {
487 log_err("cannot get docroot information (%s)\n", target_homedir);
492 if (((chdir(AP_DOC_ROOT)) != 0) ||
493 ((getcwd(dwd, AP_MAXPATH)) == NULL) ||
494 ((chdir(cwd)) != 0)) {
495 log_err("cannot get docroot information (%s)\n", AP_DOC_ROOT);
500 if ((strncmp(cwd, dwd, strlen(dwd))) != 0) {
501 log_err("command not in docroot (%s/%s)\n", cwd, cmd);
506 * Stat the cwd and verify it is a directory, or error out.
508 if (((lstat(cwd, &dir_info)) != 0) || !(S_ISDIR(dir_info.st_mode))) {
509 log_err("cannot stat directory: (%s)\n", cwd);
514 * Error out if cwd is writable by others.
516 if ((dir_info.st_mode & S_IWOTH) || (dir_info.st_mode & S_IWGRP)) {
517 log_err("directory is writable by others: (%s)\n", cwd);
522 * Error out if we cannot stat the program.
524 if (((lstat(cmd, &prg_info)) != 0) || (S_ISLNK(prg_info.st_mode))) {
525 log_err("cannot stat program: (%s)\n", cmd);
530 * Error out if the program is writable by others.
532 if ((prg_info.st_mode & S_IWOTH) || (prg_info.st_mode & S_IWGRP)) {
533 log_err("file is writable by others: (%s/%s)\n", cwd, cmd);
538 * Error out if the file is setuid or setgid.
540 if ((prg_info.st_mode & S_ISUID) || (prg_info.st_mode & S_ISGID)) {
541 log_err("file is either setuid or setgid: (%s/%s)\n", cwd, cmd);
546 * Error out if the target name/group is different from
547 * the name/group of the cwd or the program.
549 if ((uid != dir_info.st_uid) ||
550 (gid != dir_info.st_gid) ||
551 (uid != prg_info.st_uid) ||
552 (gid != prg_info.st_gid)) {
553 log_err("target uid/gid (%ld/%ld) mismatch "
554 "with directory (%ld/%ld) or program (%ld/%ld)\n",
556 dir_info.st_uid, dir_info.st_gid,
557 prg_info.st_uid, prg_info.st_gid);
561 * Error out if the program is not executable for the user.
562 * Otherwise, she won't find any error in the logs except for
563 * "[error] Premature end of script headers: ..."
565 if (!(prg_info.st_mode & S_IXUSR)) {
566 log_err("file has no execute permission: (%s/%s)\n", cwd, cmd);
570 #ifdef AP_SUEXEC_UMASK
572 * umask() uses inverse logic; bits are CLEAR for allowed access.
574 if ((~AP_SUEXEC_UMASK) & 0022) {
575 log_err("notice: AP_SUEXEC_UMASK of %03o allows "
576 "write permission to group and/or other\n", AP_SUEXEC_UMASK);
578 umask(AP_SUEXEC_UMASK);
579 #endif /* AP_SUEXEC_UMASK */
582 * Be sure to close the log file so the CGI can't
583 * mess with it. If the exec fails, it will be reopened
584 * automatically when log_err is called. Note that the log
585 * might not actually be open if AP_LOG_EXEC isn't defined.
586 * However, the "log" cell isn't ifdef'd so let's be defensive
587 * and assume someone might have done something with it
588 * outside an ifdef'd AP_LOG_EXEC block.
596 * Execute the command, replacing our image with its own.
598 #ifdef NEED_HASHBANG_EMUL
599 /* We need the #! emulation when we want to execute scripts */
601 extern char **environ;
603 ap_execve(cmd, &argv[3], environ);
605 #else /*NEED_HASHBANG_EMUL*/
606 execv(cmd, &argv[3]);
607 #endif /*NEED_HASHBANG_EMUL*/
610 * (I can't help myself...sorry.)
612 * Uh oh. Still here. Where's the kaboom? There was supposed to be an
613 * EARTH-shattering kaboom!
615 * Oh well, log the failure and error out.
617 log_err("(%d)%s: exec failed (%s)\n", errno, strerror(errno), cmd);