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/* ====================================================================
* Copyright (c) 1995-1997 The Apache Group. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the Apache Group
* for use in the Apache HTTP server project (http://www.apache.org/)."
*
* 4. The names "Apache Server" and "Apache Group" must not be used to
* endorse or promote products derived from this software without
* prior written permission.
*
* 5. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the Apache Group
* for use in the Apache HTTP server project (http://www.apache.org/)."
*
* THIS SOFTWARE IS PROVIDED BY THE APACHE GROUP ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE APACHE GROUP OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Group and was originally based
* on public domain software written at the National Center for
* Supercomputing Applications, University of Illinois, Urbana-Champaign.
* For more information on the Apache Group and the Apache HTTP server
* project, please see <http://www.apache.org/>.
*
*/
/*
* suexec.c -- "Wrapper" support program for suEXEC behaviour for Apache
*
***********************************************************************
*
* NOTE! : DO NOT edit this code!!! Unless you know what you are doing,
* editing this code might open up your system in unexpected
* ways to would-be crackers. Every precaution has been taken
* to make this code as safe as possible; alter it at your own
* risk.
*
***********************************************************************
*
*
*/
#include "suexec.h"
#include <sys/param.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <pwd.h>
#include <grp.h>
#include <time.h>
#include <sys/stat.h>
/*
***********************************************************************
* There is no initgroups() in QNX, so I believe this is safe :-)
* Use cc -osuexec -3 -O -mf -DQNX suexec.c to compile.
*
* May 17, 1997.
* Igor N. Kovalenko -- infoh@mail.wplus.net
***********************************************************************
*/
#if defined(QNX)
int initgroups(const char *name, gid_t basegid)
{
/* QNX and MPE do not appear to support supplementary groups. */
return 0;
}
#endif
#if defined(PATH_MAX)
#define AP_MAXPATH PATH_MAX
#elif defined(MAXPATHLEN)
#define AP_MAXPATH MAXPATHLEN
#else
#define AP_MAXPATH 8192
#endif
#define AP_ENVBUF 256
extern char **environ;
static FILE *log;
char *safe_env_lst[] =
{
"AUTH_TYPE",
"CONTENT_LENGTH",
"CONTENT_TYPE",
"DATE_GMT",
"DATE_LOCAL",
"DOCUMENT_NAME",
"DOCUMENT_PATH_INFO",
"DOCUMENT_ROOT",
"DOCUMENT_URI",
"FILEPATH_INFO",
"GATEWAY_INTERFACE",
"LAST_MODIFIED",
"PATH_INFO",
"PATH_TRANSLATED",
"QUERY_STRING",
"QUERY_STRING_UNESCAPED",
"REMOTE_ADDR",
"REMOTE_HOST",
"REMOTE_IDENT",
"REMOTE_PORT",
"REMOTE_USER",
"REDIRECT_QUERY_STRING",
"REDIRECT_STATUS",
"REDIRECT_URL",
"REQUEST_METHOD",
"SCRIPT_FILENAME",
"SCRIPT_NAME",
"SCRIPT_URI",
"SCRIPT_URL",
"SERVER_ADMIN",
"SERVER_NAME",
"SERVER_PORT",
"SERVER_PROTOCOL",
"SERVER_SOFTWARE",
"USER_NAME",
"TZ",
NULL
};
static void err_output(const char *fmt, va_list ap)
{
time_t timevar;
struct tm *lt;
if (!log)
if ((log = fopen(LOG_EXEC, "a")) == NULL) {
fprintf(stderr, "failed to open log file\n");
perror("fopen");
exit(1);
}
time(&timevar);
lt = localtime(&timevar);
fprintf(log, "[%.2d:%.2d:%.2d %.2d-%.2d-%.2d]: ", lt->tm_hour, lt->tm_min,
lt->tm_sec, lt->tm_mday, (lt->tm_mon + 1), lt->tm_year);
vfprintf(log, fmt, ap);
fflush(log);
return;
}
void log_err(const char *fmt, ...)
{
#ifdef LOG_EXEC
va_list ap;
va_start(ap, fmt);
err_output(fmt, ap);
va_end(ap);
#endif /* LOG_EXEC */
return;
}
void clean_env()
{
char pathbuf[512];
char **cleanenv;
char **ep;
int cidx = 0;
int idx;
if ((cleanenv = (char **)calloc(AP_ENVBUF, sizeof(char *))) == NULL) {
log_err("failed to malloc env mem\n");
exit(120);
}
for (ep = environ; *ep && cidx < AP_ENVBUF; ep++) {
if (!strncmp(*ep, "HTTP_", 5)) {
cleanenv[cidx] = *ep;
cidx++;
}
else {
for (idx = 0; safe_env_lst[idx]; idx++) {
if (!strncmp(*ep, safe_env_lst[idx], strlen(safe_env_lst[idx]))) {
cleanenv[cidx] = *ep;
cidx++;
break;
}
}
}
}
sprintf(pathbuf, "PATH=%s", SAFE_PATH);
cleanenv[cidx] = strdup(pathbuf);
cleanenv[++cidx] = NULL;
environ = cleanenv;
}
int main(int argc, char *argv[])
{
int userdir = 0; /* ~userdir flag */
uid_t uid; /* user information */
gid_t gid; /* target group placeholder */
char *target_uname; /* target user name */
char *target_gname; /* target group name */
char *target_homedir; /* target home directory */
char *actual_uname; /* actual user name */
char *actual_gname; /* actual group name */
char *prog; /* name of this program */
char *cmd; /* command to be executed */
char cwd[AP_MAXPATH]; /* current working directory */
char dwd[AP_MAXPATH]; /* docroot working directory */
struct passwd *pw; /* password entry holder */
struct group *gr; /* group entry holder */
struct stat dir_info; /* directory info holder */
struct stat prg_info; /* program info holder */
/*
* If there are a proper number of arguments, set
* all of them to variables. Otherwise, error out.
*/
prog = argv[0];
if (argc < 4) {
log_err("too few arguments\n");
exit(101);
}
target_uname = argv[1];
target_gname = argv[2];
cmd = argv[3];
/*
* Check existence/validity of the UID of the user
* running this program. Error out if invalid.
*/
uid = getuid();
if ((pw = getpwuid(uid)) == NULL) {
log_err("invalid uid: (%ld)\n", uid);
exit(102);
}
/*
* Check to see if the user running this program
* is the user allowed to do so as defined in
* suexec.h. If not the allowed user, error out.
*/
if (strcmp(HTTPD_USER, pw->pw_name)) {
log_err("user mismatch (%s)\n", pw->pw_name);
exit(103);
}
/*
* Check for a leading '/' (absolute path) in the command to be executed,
* or attempts to back up out of the current directory,
* to protect against attacks. If any are
* found, error out. Naughty naughty crackers.
*/
if (
(cmd[0] == '/') ||
(! strncmp (cmd, "../", 3)) ||
(strstr (cmd, "/../") != NULL)
) {
log_err("invalid command (%s)\n", cmd);
exit(104);
}
/*
* Check to see if this is a ~userdir request. If
* so, set the flag, and remove the '~' from the
* target username.
*/
if (!strncmp("~", target_uname, 1)) {
target_uname++;
userdir = 1;
}
/*
* Error out if the target username is invalid.
*/
if ((pw = getpwnam(target_uname)) == NULL) {
log_err("invalid target user name: (%s)\n", target_uname);
exit(105);
}
/*
* Error out if the target group name is invalid.
*/
if (strspn(target_gname, "1234567890") != strlen(target_gname)) {
if ((gr = getgrnam(target_gname)) == NULL) {
log_err("invalid target group name: (%s)\n", target_gname);
exit(106);
}
gid = gr->gr_gid;
actual_gname = strdup(gr->gr_name);
}
else {
gid = atoi(target_gname);
actual_gname = strdup(target_gname);
}
/*
* Save these for later since initgroups will hose the struct
*/
uid = pw->pw_uid;
actual_uname = strdup(pw->pw_name);
target_homedir = strdup(pw->pw_dir);
/*
* Log the transaction here to be sure we have an open log
* before we setuid().
*/
log_err("uid: (%s/%s) gid: (%s/%s) %s\n",
target_uname, actual_uname,
target_gname, actual_gname,
cmd);
/*
* Error out if attempt is made to execute as root or as
* a UID less than UID_MIN. Tsk tsk.
*/
if ((uid == 0) ||
(uid < UID_MIN)) {
log_err("cannot run as forbidden uid (%d/%s)\n", uid, cmd);
exit(107);
}
/*
* Error out if attempt is made to execute as root group
* or as a GID less than GID_MIN. Tsk tsk.
*/
if ((gid == 0) ||
(gid < GID_MIN)) {
log_err("cannot run as forbidden gid (%d/%s)\n", gid, cmd);
exit(108);
}
/*
* Change UID/GID here so that the following tests work over NFS.
*
* Initialize the group access list for the target user,
* and setgid() to the target group. If unsuccessful, error out.
*/
if (((setgid(gid)) != 0) || (initgroups(actual_uname,gid) != 0)) {
log_err("failed to setgid (%ld: %s/%s)\n", gid, cwd, cmd);
exit(109);
}
/*
* setuid() to the target user. Error out on fail.
*/
if ((setuid(uid)) != 0) {
log_err("failed to setuid (%ld: %s/%s)\n", uid, cwd, cmd);
exit(110);
}
/*
* Get the current working directory, as well as the proper
* document root (dependant upon whether or not it is a
* ~userdir request). Error out if we cannot get either one,
* or if the current working directory is not in the docroot.
* Use chdir()s and getcwd()s to avoid problems with symlinked
* directories. Yuck.
*/
if (getcwd(cwd, AP_MAXPATH) == NULL) {
log_err("cannot get current working directory\n");
exit(111);
}
if (userdir) {
if (((chdir(target_homedir)) != 0) ||
((chdir(USERDIR_SUFFIX)) != 0) ||
((getcwd(dwd, AP_MAXPATH)) == NULL) ||
((chdir(cwd)) != 0))
{
log_err("cannot get docroot information (%s)\n", target_homedir);
exit(112);
}
}
else {
if (((chdir(DOC_ROOT)) != 0) ||
((getcwd(dwd, AP_MAXPATH)) == NULL) ||
((chdir(cwd)) != 0))
{
log_err("cannot get docroot information (%s)\n", DOC_ROOT);
exit(113);
}
}
if ((strncmp(cwd, dwd, strlen(dwd))) != 0) {
log_err("command not in docroot (%s/%s)\n", cwd, cmd);
exit(114);
}
/*
* Stat the cwd and verify it is a directory, or error out.
*/
if (((lstat(cwd, &dir_info)) != 0) || !(S_ISDIR(dir_info.st_mode))) {
log_err("cannot stat directory: (%s)\n", cwd);
exit(115);
}
/*
* Error out if cwd is writable by others.
*/
if ((dir_info.st_mode & S_IWOTH) || (dir_info.st_mode & S_IWGRP)) {
log_err("directory is writable by others: (%s)\n", cwd);
exit(116);
}
/*
* Error out if we cannot stat the program.
*/
if (((lstat(cmd, &prg_info)) != 0) || (S_ISLNK(prg_info.st_mode))) {
log_err("cannot stat program: (%s)\n", cmd);
exit(117);
}
/*
* Error out if the program is writable by others.
*/
if ((prg_info.st_mode & S_IWOTH) || (prg_info.st_mode & S_IWGRP)) {
log_err("file is writable by others: (%s/%s)\n", cwd, cmd);
exit(118);
}
/*
* Error out if the file is setuid or setgid.
*/
if ((prg_info.st_mode & S_ISUID) || (prg_info.st_mode & S_ISGID)) {
log_err("file is either setuid or setgid: (%s/%s)\n",cwd,cmd);
exit(119);
}
/*
* Error out if the target name/group is different from
* the name/group of the cwd or the program.
*/
if ((uid != dir_info.st_uid) ||
(gid != dir_info.st_gid) ||
(uid != prg_info.st_uid) ||
(gid != prg_info.st_gid))
{
log_err("target uid/gid (%ld/%ld) mismatch with directory (%ld/%ld) or program (%ld/%ld)\n",
uid, gid,
dir_info.st_uid, dir_info.st_gid,
prg_info.st_uid, prg_info.st_gid);
exit(120);
}
clean_env();
/*
* Be sure to close the log file so the CGI can't
* mess with it. If the exec fails, it will be reopened
* automatically when log_err is called.
*/
fclose(log);
log = NULL;
/*
* Execute the command, replacing our image with its own.
*/
execv(cmd, &argv[3]);
/*
* (I can't help myself...sorry.)
*
* Uh oh. Still here. Where's the kaboom? There was supposed to be an
* EARTH-shattering kaboom!
*
* Oh well, log the failure and error out.
*/
log_err("exec failed (%s)\n", cmd);
exit(255);
}
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