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>
62 #define AP_MAXPATH PATH_MAX
63 #elif defined(MAXPATHLEN)
64 #define AP_MAXPATH MAXPATHLEN
66 #define AP_MAXPATH 8192
71 extern char **environ;
72 static FILE *log = NULL;
74 static const char *const safe_env_lst[] =
76 /* variable name starts with */
80 /* variable name is */
84 "CONTEXT_DOCUMENT_ROOT=",
89 "DOCUMENT_PATH_INFO=",
98 "QUERY_STRING_UNESCAPED=",
104 "REDIRECT_ERROR_NOTES=",
106 "REDIRECT_QUERY_STRING=",
107 "REDIRECT_REMOTE_USER=",
108 "REDIRECT_SCRIPT_FILENAME=",
131 static void log_err(const char *fmt,...)
132 __attribute__((format(printf,1,2)));
133 static void log_no_err(const char *fmt,...)
134 __attribute__((format(printf,1,2)));
135 static void err_output(int is_error, const char *fmt, va_list ap)
136 __attribute__((format(printf,2,0)));
138 static void err_output(int is_error, const char *fmt, va_list ap)
145 #if defined(_LARGEFILE64_SOURCE) && HAVE_FOPEN64
146 if ((log = fopen64(AP_LOG_EXEC, "a")) == NULL) {
148 if ((log = fopen(AP_LOG_EXEC, "a")) == NULL) {
150 fprintf(stderr, "suexec failure: could not open log file\n");
157 fprintf(stderr, "suexec policy violation: see suexec log for more "
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,...)
181 err_output(1, fmt, ap); /* 1 == is_error */
183 #endif /* AP_LOG_EXEC */
187 static void log_no_err(const char *fmt,...)
193 err_output(0, fmt, ap); /* 0 == !is_error */
195 #endif /* AP_LOG_EXEC */
199 static void clean_env(void)
207 /* While cleaning the environment, the environment should be clean.
208 * (e.g. malloc() may get the name of a file for writing debugging info.
209 * Bad news if MALLOC_DEBUG_FILE is set to /etc/passwd. Sprintf() may be
210 * susceptible to bad locale settings....)
213 char **envp = environ;
214 char *empty_ptr = NULL;
216 environ = &empty_ptr; /* VERY safe environment */
218 if ((cleanenv = (char **) calloc(AP_ENVBUF, sizeof(char *))) == NULL) {
219 log_err("failed to malloc memory for environment\n");
223 sprintf(pathbuf, "PATH=%s", AP_SAFE_PATH);
224 cleanenv[cidx] = strdup(pathbuf);
225 if (cleanenv[cidx] == NULL) {
226 log_err("failed to malloc memory for environment\n");
231 for (ep = envp; *ep && cidx < AP_ENVBUF-1; ep++) {
232 for (idx = 0; safe_env_lst[idx]; idx++) {
233 if (!strncmp(*ep, safe_env_lst[idx],
234 strlen(safe_env_lst[idx]))) {
235 cleanenv[cidx] = *ep;
242 cleanenv[cidx] = NULL;
247 int main(int argc, char *argv[])
249 int userdir = 0; /* ~userdir flag */
250 uid_t uid; /* user information */
251 gid_t gid; /* target group placeholder */
252 char *target_uname; /* target user name */
253 char *target_gname; /* target group name */
254 char *target_homedir; /* target home directory */
255 char *actual_uname; /* actual user name */
256 char *actual_gname; /* actual group name */
257 char *cmd; /* command to be executed */
258 char cwd[AP_MAXPATH]; /* current working directory */
259 char dwd[AP_MAXPATH]; /* docroot working directory */
260 struct passwd *pw; /* password entry holder */
261 struct group *gr; /* group entry holder */
262 struct stat dir_info; /* directory info holder */
263 struct stat prg_info; /* program info holder */
266 * Start with a "clean" environment
271 * Check existence/validity of the UID of the user
272 * running this program. Error out if invalid.
275 if ((pw = getpwuid(uid)) == NULL) {
276 log_err("crit: invalid uid: (%lu)\n", (unsigned long)uid);
280 * See if this is a 'how were you compiled' request, and
284 && (! strcmp(argv[1], "-V"))
287 /* User name comparisons are case insensitive on BS2000/OSD */
288 || (! strcasecmp(AP_HTTPD_USER, pw->pw_name)))
289 #else /* _OSD_POSIX */
290 || (! strcmp(AP_HTTPD_USER, pw->pw_name)))
291 #endif /* _OSD_POSIX */
294 fprintf(stderr, " -D AP_DOC_ROOT=\"%s\"\n", AP_DOC_ROOT);
297 fprintf(stderr, " -D AP_GID_MIN=%d\n", AP_GID_MIN);
300 fprintf(stderr, " -D AP_HTTPD_USER=\"%s\"\n", AP_HTTPD_USER);
303 fprintf(stderr, " -D AP_LOG_EXEC=\"%s\"\n", AP_LOG_EXEC);
306 fprintf(stderr, " -D AP_SAFE_PATH=\"%s\"\n", AP_SAFE_PATH);
308 #ifdef AP_SUEXEC_UMASK
309 fprintf(stderr, " -D AP_SUEXEC_UMASK=%03o\n", AP_SUEXEC_UMASK);
312 fprintf(stderr, " -D AP_UID_MIN=%d\n", AP_UID_MIN);
314 #ifdef AP_USERDIR_SUFFIX
315 fprintf(stderr, " -D AP_USERDIR_SUFFIX=\"%s\"\n", AP_USERDIR_SUFFIX);
320 * If there are a proper number of arguments, set
321 * all of them to variables. Otherwise, error out.
324 log_err("too few arguments\n");
327 target_uname = argv[1];
328 target_gname = argv[2];
332 * Check to see if the user running this program
333 * is the user allowed to do so as defined in
334 * suexec.h. If not the allowed user, error out.
337 /* User name comparisons are case insensitive on BS2000/OSD */
338 if (strcasecmp(AP_HTTPD_USER, pw->pw_name)) {
339 log_err("user mismatch (%s instead of %s)\n", pw->pw_name, AP_HTTPD_USER);
343 if (strcmp(AP_HTTPD_USER, pw->pw_name)) {
344 log_err("user mismatch (%s instead of %s)\n", pw->pw_name, AP_HTTPD_USER);
347 #endif /*_OSD_POSIX*/
350 * Check for a leading '/' (absolute path) in the command to be executed,
351 * or attempts to back up out of the current directory,
352 * to protect against attacks. If any are
353 * found, error out. Naughty naughty crackers.
355 if ((cmd[0] == '/') || (!strncmp(cmd, "../", 3))
356 || (strstr(cmd, "/../") != NULL)) {
357 log_err("invalid command (%s)\n", cmd);
362 * Check to see if this is a ~userdir request. If
363 * so, set the flag, and remove the '~' from the
366 if (!strncmp("~", target_uname, 1)) {
372 * Error out if the target username is invalid.
374 if (strspn(target_uname, "1234567890") != strlen(target_uname)) {
375 if ((pw = getpwnam(target_uname)) == NULL) {
376 log_err("invalid target user name: (%s)\n", target_uname);
381 if ((pw = getpwuid(atoi(target_uname))) == NULL) {
382 log_err("invalid target user id: (%s)\n", target_uname);
388 * Error out if the target group name is invalid.
390 if (strspn(target_gname, "1234567890") != strlen(target_gname)) {
391 if ((gr = getgrnam(target_gname)) == NULL) {
392 log_err("invalid target group name: (%s)\n", target_gname);
397 if ((gr = getgrgid(atoi(target_gname))) == NULL) {
398 log_err("invalid target group id: (%s)\n", target_gname);
403 if ((actual_gname = strdup(gr->gr_name)) == NULL) {
404 log_err("failed to alloc memory\n");
410 * Initialize BS2000 user environment
416 switch (pid = ufork(target_uname)) {
418 log_err("failed to setup bs2000 environment for user %s: %s\n",
419 target_uname, strerror(errno));
423 default: /* Father */
424 while (pid != waitpid(pid, &status, 0))
426 /* @@@ FIXME: should we deal with STOP signals as well? */
427 if (WIFSIGNALED(status)) {
428 kill (getpid(), WTERMSIG(status));
430 exit(WEXITSTATUS(status));
433 #endif /*_OSD_POSIX*/
436 * Save these for later since initgroups will hose the struct
439 actual_uname = strdup(pw->pw_name);
440 target_homedir = strdup(pw->pw_dir);
441 if (actual_uname == NULL || target_homedir == NULL) {
442 log_err("failed to alloc memory\n");
447 * Log the transaction here to be sure we have an open log
448 * before we setuid().
450 log_no_err("uid: (%s/%s) gid: (%s/%s) cmd: %s\n",
451 target_uname, actual_uname,
452 target_gname, actual_gname,
456 * Error out if attempt is made to execute as root or as
457 * a UID less than AP_UID_MIN. Tsk tsk.
459 if ((uid == 0) || (uid < AP_UID_MIN)) {
460 log_err("cannot run as forbidden uid (%lu/%s)\n", (unsigned long)uid, cmd);
465 * Error out if attempt is made to execute as root group
466 * or as a GID less than AP_GID_MIN. Tsk tsk.
468 if ((gid == 0) || (gid < AP_GID_MIN)) {
469 log_err("cannot run as forbidden gid (%lu/%s)\n", (unsigned long)gid, cmd);
474 * Change UID/GID here so that the following tests work over NFS.
476 * Initialize the group access list for the target user,
477 * and setgid() to the target group. If unsuccessful, error out.
479 if (((setgid(gid)) != 0) || (initgroups(actual_uname, gid) != 0)) {
480 log_err("failed to setgid (%lu: %s)\n", (unsigned long)gid, cmd);
485 * setuid() to the target user. Error out on fail.
487 if ((setuid(uid)) != 0) {
488 log_err("failed to setuid (%lu: %s)\n", (unsigned long)uid, cmd);
493 * Get the current working directory, as well as the proper
494 * document root (dependant upon whether or not it is a
495 * ~userdir request). Error out if we cannot get either one,
496 * or if the current working directory is not in the docroot.
497 * Use chdir()s and getcwd()s to avoid problems with symlinked
500 if (getcwd(cwd, AP_MAXPATH) == NULL) {
501 log_err("cannot get current working directory\n");
506 if (((chdir(target_homedir)) != 0) ||
507 ((chdir(AP_USERDIR_SUFFIX)) != 0) ||
508 ((getcwd(dwd, AP_MAXPATH)) == NULL) ||
509 ((chdir(cwd)) != 0)) {
510 log_err("cannot get docroot information (%s)\n", target_homedir);
515 if (((chdir(AP_DOC_ROOT)) != 0) ||
516 ((getcwd(dwd, AP_MAXPATH)) == NULL) ||
517 ((chdir(cwd)) != 0)) {
518 log_err("cannot get docroot information (%s)\n", AP_DOC_ROOT);
523 if ((strncmp(cwd, dwd, strlen(dwd))) != 0) {
524 log_err("command not in docroot (%s/%s)\n", cwd, cmd);
529 * Stat the cwd and verify it is a directory, or error out.
531 if (((lstat(cwd, &dir_info)) != 0) || !(S_ISDIR(dir_info.st_mode))) {
532 log_err("cannot stat directory: (%s)\n", cwd);
537 * Error out if cwd is writable by others.
539 if ((dir_info.st_mode & S_IWOTH) || (dir_info.st_mode & S_IWGRP)) {
540 log_err("directory is writable by others: (%s)\n", cwd);
545 * Error out if we cannot stat the program.
547 if (((lstat(cmd, &prg_info)) != 0) || (S_ISLNK(prg_info.st_mode))) {
548 log_err("cannot stat program: (%s)\n", cmd);
553 * Error out if the program is writable by others.
555 if ((prg_info.st_mode & S_IWOTH) || (prg_info.st_mode & S_IWGRP)) {
556 log_err("file is writable by others: (%s/%s)\n", cwd, cmd);
561 * Error out if the file is setuid or setgid.
563 if ((prg_info.st_mode & S_ISUID) || (prg_info.st_mode & S_ISGID)) {
564 log_err("file is either setuid or setgid: (%s/%s)\n", cwd, cmd);
569 * Error out if the target name/group is different from
570 * the name/group of the cwd or the program.
572 if ((uid != dir_info.st_uid) ||
573 (gid != dir_info.st_gid) ||
574 (uid != prg_info.st_uid) ||
575 (gid != prg_info.st_gid)) {
576 log_err("target uid/gid (%lu/%lu) mismatch "
577 "with directory (%lu/%lu) or program (%lu/%lu)\n",
578 (unsigned long)uid, (unsigned long)gid,
579 (unsigned long)dir_info.st_uid, (unsigned long)dir_info.st_gid,
580 (unsigned long)prg_info.st_uid, (unsigned long)prg_info.st_gid);
584 * Error out if the program is not executable for the user.
585 * Otherwise, she won't find any error in the logs except for
586 * "[error] Premature end of script headers: ..."
588 if (!(prg_info.st_mode & S_IXUSR)) {
589 log_err("file has no execute permission: (%s/%s)\n", cwd, cmd);
593 #ifdef AP_SUEXEC_UMASK
595 * umask() uses inverse logic; bits are CLEAR for allowed access.
597 if ((~AP_SUEXEC_UMASK) & 0022) {
598 log_err("notice: AP_SUEXEC_UMASK of %03o allows "
599 "write permission to group and/or other\n", AP_SUEXEC_UMASK);
601 umask(AP_SUEXEC_UMASK);
602 #endif /* AP_SUEXEC_UMASK */
604 /* Be sure to close the log file so the CGI can't mess with it. */
608 * ask fcntl(2) to set the FD_CLOEXEC flag on the log file,
609 * so it'll be automagically closed if the exec() call succeeds.
613 if ((fcntl(fileno(log), F_SETFD, FD_CLOEXEC) == -1)) {
614 log_err("error: can't set close-on-exec flag");
619 * In this case, exec() errors won't be logged because we have already
620 * dropped privileges and won't be able to reopen the log file.
628 * Execute the command, replacing our image with its own.
630 #ifdef NEED_HASHBANG_EMUL
631 /* We need the #! emulation when we want to execute scripts */
633 extern char **environ;
635 ap_execve(cmd, &argv[3], environ);
637 #else /*NEED_HASHBANG_EMUL*/
638 execv(cmd, &argv[3]);
639 #endif /*NEED_HASHBANG_EMUL*/
642 * (I can't help myself...sorry.)
644 * Uh oh. Still here. Where's the kaboom? There was supposed to be an
645 * EARTH-shattering kaboom!
647 * Oh well, log the failure and error out.
649 log_err("(%d)%s: exec failed (%s)\n", errno, strerror(errno), cmd);