/* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* 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.
*
***********************************************************************
*
*
* Error messages in the suexec logfile are prefixed with severity values
* similar to those used by the main server:
*
* Sev Meaning
* emerg: Failure of some basic system function
* alert: Bug in the way Apache is communicating with suexec
* crit: Basic information is missing, invalid, or incorrect
* error: Script permission/configuration error
* warn:
* notice: Some issue of which the sysadmin/webmaster ought to be aware
* info: Normal activity message
* debug: Self-explanatory
*/
#include "ap_config.h"
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <stdarg.h>
#include "suexec.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(NEED_INITGROUPS)
int initgroups(const char *name, gid_t basegid)
{
/* QNX and MPE do not appear to support supplementary groups. */
return 0;
}
#endif
#if defined(NEED_STRERROR)
extern char *sys_errlist[];
#define strerror(x) sys_errlist[(x)]
#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 = NULL;
char *safe_env_lst[] =
{
/* variable name starts with */
"HTTP_",
"HTTPS",
"SSL_",
/* variable name is */
"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=",
"REQUEST_URI=",
"SCRIPT_FILENAME=",
"SCRIPT_NAME=",
"SCRIPT_URI=",
"SCRIPT_URL=",
"SERVER_ADMIN=",
"SERVER_NAME=",
"SERVER_ADDR=",
"SERVER_PORT=",
"SERVER_PROTOCOL=",
"SERVER_SOFTWARE=",
"UNIQUE_ID=",
"USER_NAME=",
"TZ=",
NULL
};
static void err_output(const char *fmt, va_list ap)
{
#ifdef LOG_EXEC
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, "[%d-%.2d-%.2d %.2d:%.2d:%.2d]: ",
lt->tm_year + 1900, lt->tm_mon + 1, lt->tm_mday,
lt->tm_hour, lt->tm_min, lt->tm_sec);
vfprintf(log, fmt, ap);
fflush(log);
#endif /* LOG_EXEC */
return;
}
static 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;
}
static void clean_env(void)
{
char pathbuf[512];
char **cleanenv;
char **ep;
int cidx = 0;
int idx;
/* While cleaning the environment, the environment should be clean.
* (e.g. malloc() may get the name of a file for writing debugging info.
* Bad news if MALLOC_DEBUG_FILE is set to /etc/passwd. Sprintf() may be
* susceptible to bad locale settings....)
* (from PR 2790)
*/
char **envp = environ;
char *empty_ptr = NULL;
environ = &empty_ptr; /* VERY safe environment */
if ((cleanenv = (char **) calloc(AP_ENVBUF, sizeof(char *))) == NULL) {
log_err("emerg: failed to malloc memory for environment\n");
exit(120);
}
sprintf(pathbuf, "PATH=%s", SAFE_PATH);
cleanenv[cidx] = strdup(pathbuf);
cidx++;
for (ep = envp; *ep && cidx < AP_ENVBUF-1; ep++) {
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;
}
}
}
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 */
/*
* Start with a "clean" environment
*/
clean_env();
prog = argv[0];
/*
* 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("crit: invalid uid: (%ld)\n", uid);
exit(102);
}
/*
* See if this is a 'how were you compiled' request, and
* comply if so.
*/
if ((argc > 1)
&& (! strcmp(argv[1], "-V"))
&& ((uid == 0)
#ifdef _OSD_POSIX
/* User name comparisons are case insensitive on BS2000/OSD */
|| (! strcasecmp(HTTPD_USER, pw->pw_name)))
#else /* _OSD_POSIX */
|| (! strcmp(HTTPD_USER, pw->pw_name)))
#endif /* _OSD_POSIX */
) {
#ifdef DOC_ROOT
fprintf(stderr, " -D DOC_ROOT=\"%s\"\n", DOC_ROOT);
#endif
#ifdef GID_MIN
fprintf(stderr, " -D GID_MIN=%d\n", GID_MIN);
#endif
#ifdef HTTPD_USER
fprintf(stderr, " -D HTTPD_USER=\"%s\"\n", HTTPD_USER);
#endif
#ifdef LOG_EXEC
fprintf(stderr, " -D LOG_EXEC=\"%s\"\n", LOG_EXEC);
#endif
#ifdef SAFE_PATH
fprintf(stderr, " -D SAFE_PATH=\"%s\"\n", SAFE_PATH);
#endif
#ifdef SUEXEC_UMASK
fprintf(stderr, " -D SUEXEC_UMASK=%03o\n", SUEXEC_UMASK);
#endif
#ifdef UID_MIN
fprintf(stderr, " -D UID_MIN=%d\n", UID_MIN);
#endif
#ifdef USERDIR_SUFFIX
fprintf(stderr, " -D USERDIR_SUFFIX=\"%s\"\n", USERDIR_SUFFIX);
#endif
exit(0);
}
/*
* If there are a proper number of arguments, set
* all of them to variables. Otherwise, error out.
*/
if (argc < 4) {
log_err("alert: too few arguments\n");
exit(101);
}
target_uname = argv[1];
target_gname = argv[2];
cmd = argv[3];
/*
* 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.
*/
#ifdef _OSD_POSIX
/* User name comparisons are case insensitive on BS2000/OSD */
if (strcasecmp(HTTPD_USER, pw->pw_name)) {
log_err("crit: calling user mismatch (%s instead of %s)\n",
pw->pw_name, HTTPD_USER);
exit(103);
}
#else /* _OSD_POSIX */
if (strcmp(HTTPD_USER, pw->pw_name)) {
log_err("crit: calling user mismatch (%s instead of %s)\n",
pw->pw_name, HTTPD_USER);
exit(103);
}
#endif /* _OSD_POSIX */
/*
* 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("error: 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("crit: 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("crit: 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);
}
#ifdef _OSD_POSIX
/*
* Initialize BS2000 user environment
*/
{
pid_t pid, reaped;
int status;
switch (pid = ufork(target_uname))
{
case -1: /* Error */
log_err("emerg: failed to setup bs2000 environment for user "
"%s: %s\n",
target_uname, strerror(errno));
exit(150);
case 0: /* Child */
break;
default: /* Father */
while (pid != (reaped = waitpid(pid, &status, 0))
&& (reaped != -1 || errno != ECHILD))
;
/* @@@ FIXME: should we deal with STOP signals as well? */
if (WIFSIGNALED(status)) {
kill (getpid(), WTERMSIG(status));
}
exit(WEXITSTATUS(status));
}
}
#endif /* _OSD_POSIX */
/*
* 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("info: (target/actual) uid: (%s/%s) gid: (%s/%s) cmd: %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("crit: 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("crit: 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("emerg: failed to setgid (%ld: %s)\n", gid, cmd);
exit(109);
}
/*
* setuid() to the target user. Error out on fail.
*/
if ((setuid(uid)) != 0) {
log_err("emerg: failed to setuid (%ld: %s)\n", uid, 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("emerg: 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("emerg: 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("emerg: cannot get docroot information (%s)\n", DOC_ROOT);
exit(113);
}
}
if ((strncmp(cwd, dwd, strlen(dwd))) != 0) {
log_err("error: 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("error: 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("error: 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("error: 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("error: 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("error: 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("error: 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);
}
/*
* Error out if the program is not executable for the user.
* Otherwise, she won't find any error in the logs except for
* "[error] Premature end of script headers: ..."
*/
if (!(prg_info.st_mode & S_IXUSR)) {
log_err("error: file has no execute permission: (%s/%s)\n", cwd, cmd);
exit(121);
}
#ifdef SUEXEC_UMASK
/*
* umask() uses inverse logic; bits are CLEAR for allowed access.
*/
if ((~SUEXEC_UMASK) & 0022) {
log_err("notice: SUEXEC_UMASK of %03o allows "
"write permission to group and/or other\n", SUEXEC_UMASK);
}
umask(SUEXEC_UMASK);
#endif /* SUEXEC_UMASK */
/*
* 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. Note that the log
* might not actually be open if LOG_EXEC isn't defined.
* However, the "log" cell isn't ifdef'd so let's be defensive
* and assume someone might have done something with it
* outside an ifdef'd LOG_EXEC block.
*/
if (log != NULL) {
fclose(log);
log = NULL;
}
/*
* Execute the command, replacing our image with its own.
*/
#ifdef NEED_HASHBANG_EMUL
/* We need the #! emulation when we want to execute scripts */
{
extern char **environ;
ap_execve(cmd, &argv[3], environ);
}
#else /*NEED_HASHBANG_EMUL*/
execv(cmd, &argv[3]);
#endif /*NEED_HASHBANG_EMUL*/
/*
* (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("emerg: (%d)%s: exec failed (%s)\n", errno, strerror(errno), cmd);
exit(255);
}
