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/* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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* suexec.c -- "Wrapper" support program for suEXEC behaviour for Apache
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***********************************************************************
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* NOTE! : DO NOT edit this code!!! Unless you know what you are doing,
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* editing this code might open up your system in unexpected
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* ways to would-be crackers. Every precaution has been taken
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* to make this code as safe as possible; alter it at your own
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***********************************************************************
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#include "ap_config.h"
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#include <sys/param.h>
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#include <sys/types.h>
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***********************************************************************
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* There is no initgroups() in QNX, so I believe this is safe :-)
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* Use cc -osuexec -3 -O -mf -DQNX suexec.c to compile.
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* Igor N. Kovalenko -- infoh mail.wplus.net
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***********************************************************************
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#if defined(NEED_INITGROUPS)
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int initgroups(const char *name, gid_t basegid)
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/* QNX and MPE do not appear to support supplementary groups. */
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extern char *sys_errlist[];
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#define strerror(x) sys_errlist[(x)]
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#define AP_MAXPATH PATH_MAX
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#elif defined(MAXPATHLEN)
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#define AP_MAXPATH MAXPATHLEN
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#define AP_MAXPATH 8192
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extern char **environ;
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static FILE *log = NULL;
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static const char *const safe_env_lst[] =
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/* variable name starts with */
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/* variable name is */
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"DOCUMENT_PATH_INFO=",
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"GATEWAY_INTERFACE=",
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"QUERY_STRING_UNESCAPED=",
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"REDIRECT_QUERY_STRING=",
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"REDIRECT_REMOTE_USER=",
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static void err_output(int is_error, const char *fmt, va_list ap)
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if ((log = fopen(AP_LOG_EXEC, "a")) == NULL) {
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fprintf(stderr, "suexec failure: could not open log file\n");
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fprintf(stderr, "suexec policy violation: see suexec log for more "
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lt = localtime(&timevar);
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fprintf(log, "[%d-%.2d-%.2d %.2d:%.2d:%.2d]: ",
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lt->tm_year + 1900, lt->tm_mon + 1, lt->tm_mday,
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lt->tm_hour, lt->tm_min, lt->tm_sec);
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vfprintf(log, fmt, ap);
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#endif /* AP_LOG_EXEC */
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static void log_err(const char *fmt,...)
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err_output(1, fmt, ap); /* 1 == is_error */
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#endif /* AP_LOG_EXEC */
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static void log_no_err(const char *fmt,...)
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err_output(0, fmt, ap); /* 0 == !is_error */
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#endif /* AP_LOG_EXEC */
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static void clean_env(void)
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/* While cleaning the environment, the environment should be clean.
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* (e.g. malloc() may get the name of a file for writing debugging info.
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* Bad news if MALLOC_DEBUG_FILE is set to /etc/passwd. Sprintf() may be
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* susceptible to bad locale settings....)
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char **envp = environ;
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char *empty_ptr = NULL;
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environ = &empty_ptr; /* VERY safe environment */
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if ((cleanenv = (char **) calloc(AP_ENVBUF, sizeof(char *))) == NULL) {
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log_err("failed to malloc memory for environment\n");
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sprintf(pathbuf, "PATH=%s", AP_SAFE_PATH);
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cleanenv[cidx] = strdup(pathbuf);
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for (ep = envp; *ep && cidx < AP_ENVBUF-1; ep++) {
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for (idx = 0; safe_env_lst[idx]; idx++) {
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if (!strncmp(*ep, safe_env_lst[idx],
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strlen(safe_env_lst[idx]))) {
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cleanenv[cidx] = *ep;
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cleanenv[cidx] = NULL;
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int main(int argc, char *argv[])
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int userdir = 0; /* ~userdir flag */
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uid_t uid; /* user information */
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gid_t gid; /* target group placeholder */
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char *target_uname; /* target user name */
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char *target_gname; /* target group name */
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char *target_homedir; /* target home directory */
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char *actual_uname; /* actual user name */
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char *actual_gname; /* actual group name */
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char *prog; /* name of this program */
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char *cmd; /* command to be executed */
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char cwd[AP_MAXPATH]; /* current working directory */
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char dwd[AP_MAXPATH]; /* docroot working directory */
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struct passwd *pw; /* password entry holder */
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struct group *gr; /* group entry holder */
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struct stat dir_info; /* directory info holder */
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struct stat prg_info; /* program info holder */
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* Start with a "clean" environment
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* Check existence/validity of the UID of the user
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* running this program. Error out if invalid.
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if ((pw = getpwuid(uid)) == NULL) {
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log_err("crit: invalid uid: (%ld)\n", uid);
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* See if this is a 'how were you compiled' request, and
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&& (! strcmp(argv[1], "-V"))
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/* User name comparisons are case insensitive on BS2000/OSD */
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|| (! strcasecmp(AP_HTTPD_USER, pw->pw_name)))
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#else /* _OSD_POSIX */
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|| (! strcmp(AP_HTTPD_USER, pw->pw_name)))
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#endif /* _OSD_POSIX */
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fprintf(stderr, " -D AP_DOC_ROOT=\"%s\"\n", AP_DOC_ROOT);
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fprintf(stderr, " -D AP_GID_MIN=%d\n", AP_GID_MIN);
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fprintf(stderr, " -D AP_HTTPD_USER=\"%s\"\n", AP_HTTPD_USER);
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fprintf(stderr, " -D AP_LOG_EXEC=\"%s\"\n", AP_LOG_EXEC);
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fprintf(stderr, " -D AP_SAFE_PATH=\"%s\"\n", AP_SAFE_PATH);
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#ifdef AP_SUEXEC_UMASK
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fprintf(stderr, " -D AP_SUEXEC_UMASK=%03o\n", AP_SUEXEC_UMASK);
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fprintf(stderr, " -D AP_UID_MIN=%d\n", AP_UID_MIN);
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#ifdef AP_USERDIR_SUFFIX
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fprintf(stderr, " -D AP_USERDIR_SUFFIX=\"%s\"\n", AP_USERDIR_SUFFIX);
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* If there are a proper number of arguments, set
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* all of them to variables. Otherwise, error out.
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log_err("too few arguments\n");
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target_uname = argv[1];
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target_gname = argv[2];
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* Check to see if the user running this program
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* is the user allowed to do so as defined in
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* suexec.h. If not the allowed user, error out.
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/* User name comparisons are case insensitive on BS2000/OSD */
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if (strcasecmp(AP_HTTPD_USER, pw->pw_name)) {
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log_err("user mismatch (%s instead of %s)\n", pw->pw_name, AP_HTTPD_USER);
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if (strcmp(AP_HTTPD_USER, pw->pw_name)) {
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log_err("user mismatch (%s instead of %s)\n", pw->pw_name, AP_HTTPD_USER);
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#endif /*_OSD_POSIX*/
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* Check for a leading '/' (absolute path) in the command to be executed,
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* or attempts to back up out of the current directory,
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* to protect against attacks. If any are
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* found, error out. Naughty naughty crackers.
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if ((cmd[0] == '/') || (!strncmp(cmd, "../", 3))
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|| (strstr(cmd, "/../") != NULL)) {
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log_err("invalid command (%s)\n", cmd);
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* Check to see if this is a ~userdir request. If
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* so, set the flag, and remove the '~' from the
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if (!strncmp("~", target_uname, 1)) {
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* Error out if the target username is invalid.
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if (strspn(target_uname, "1234567890") != strlen(target_uname)) {
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if ((pw = getpwnam(target_uname)) == NULL) {
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log_err("invalid target user name: (%s)\n", target_uname);
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if ((pw = getpwuid(atoi(target_uname))) == NULL) {
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log_err("invalid target user id: (%s)\n", target_uname);
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* Error out if the target group name is invalid.
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if (strspn(target_gname, "1234567890") != strlen(target_gname)) {
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if ((gr = getgrnam(target_gname)) == NULL) {
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log_err("invalid target group name: (%s)\n", target_gname);
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actual_gname = strdup(gr->gr_name);
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gid = atoi(target_gname);
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actual_gname = strdup(target_gname);
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* Initialize BS2000 user environment
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switch (pid = ufork(target_uname)) {
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log_err("failed to setup bs2000 environment for user %s: %s\n",
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target_uname, strerror(errno));
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default: /* Father */
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while (pid != waitpid(pid, &status, 0))
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/* @@@ FIXME: should we deal with STOP signals as well? */
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if (WIFSIGNALED(status)) {
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kill (getpid(), WTERMSIG(status));
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exit(WEXITSTATUS(status));
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#endif /*_OSD_POSIX*/
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* Save these for later since initgroups will hose the struct
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actual_uname = strdup(pw->pw_name);
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target_homedir = strdup(pw->pw_dir);
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* Log the transaction here to be sure we have an open log
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* before we setuid().
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log_no_err("uid: (%s/%s) gid: (%s/%s) cmd: %s\n",
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target_uname, actual_uname,
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target_gname, actual_gname,
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* Error out if attempt is made to execute as root or as
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* a UID less than AP_UID_MIN. Tsk tsk.
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if ((uid == 0) || (uid < AP_UID_MIN)) {
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log_err("cannot run as forbidden uid (%d/%s)\n", uid, cmd);
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* Error out if attempt is made to execute as root group
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* or as a GID less than AP_GID_MIN. Tsk tsk.
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if ((gid == 0) || (gid < AP_GID_MIN)) {
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log_err("cannot run as forbidden gid (%d/%s)\n", gid, cmd);
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* Change UID/GID here so that the following tests work over NFS.
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* Initialize the group access list for the target user,
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* and setgid() to the target group. If unsuccessful, error out.
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if (((setgid(gid)) != 0) || (initgroups(actual_uname, gid) != 0)) {
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log_err("failed to setgid (%ld: %s)\n", gid, cmd);
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* setuid() to the target user. Error out on fail.
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if ((setuid(uid)) != 0) {
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log_err("failed to setuid (%ld: %s)\n", uid, cmd);
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* Get the current working directory, as well as the proper
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* document root (dependant upon whether or not it is a
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* ~userdir request). Error out if we cannot get either one,
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* or if the current working directory is not in the docroot.
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* Use chdir()s and getcwd()s to avoid problems with symlinked
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if (getcwd(cwd, AP_MAXPATH) == NULL) {
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log_err("cannot get current working directory\n");
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if (((chdir(target_homedir)) != 0) ||
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((chdir(AP_USERDIR_SUFFIX)) != 0) ||
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((getcwd(dwd, AP_MAXPATH)) == NULL) ||
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((chdir(cwd)) != 0)) {
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log_err("cannot get docroot information (%s)\n", target_homedir);
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if (((chdir(AP_DOC_ROOT)) != 0) ||
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((getcwd(dwd, AP_MAXPATH)) == NULL) ||
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((chdir(cwd)) != 0)) {
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log_err("cannot get docroot information (%s)\n", AP_DOC_ROOT);
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if ((strncmp(cwd, dwd, strlen(dwd))) != 0) {
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log_err("command not in docroot (%s/%s)\n", cwd, cmd);
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* Stat the cwd and verify it is a directory, or error out.
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if (((lstat(cwd, &dir_info)) != 0) || !(S_ISDIR(dir_info.st_mode))) {
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log_err("cannot stat directory: (%s)\n", cwd);
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* Error out if cwd is writable by others.
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if ((dir_info.st_mode & S_IWOTH) || (dir_info.st_mode & S_IWGRP)) {
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log_err("directory is writable by others: (%s)\n", cwd);
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* Error out if we cannot stat the program.
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if (((lstat(cmd, &prg_info)) != 0) || (S_ISLNK(prg_info.st_mode))) {
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log_err("cannot stat program: (%s)\n", cmd);
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* Error out if the program is writable by others.
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if ((prg_info.st_mode & S_IWOTH) || (prg_info.st_mode & S_IWGRP)) {
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log_err("file is writable by others: (%s/%s)\n", cwd, cmd);
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* Error out if the file is setuid or setgid.
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if ((prg_info.st_mode & S_ISUID) || (prg_info.st_mode & S_ISGID)) {
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log_err("file is either setuid or setgid: (%s/%s)\n", cwd, cmd);
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* Error out if the target name/group is different from
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* the name/group of the cwd or the program.
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if ((uid != dir_info.st_uid) ||
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(gid != dir_info.st_gid) ||
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(uid != prg_info.st_uid) ||
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(gid != prg_info.st_gid)) {
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log_err("target uid/gid (%ld/%ld) mismatch "
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"with directory (%ld/%ld) or program (%ld/%ld)\n",
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dir_info.st_uid, dir_info.st_gid,
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prg_info.st_uid, prg_info.st_gid);
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* Error out if the program is not executable for the user.
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* Otherwise, she won't find any error in the logs except for
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* "[error] Premature end of script headers: ..."
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if (!(prg_info.st_mode & S_IXUSR)) {
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log_err("file has no execute permission: (%s/%s)\n", cwd, cmd);
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#ifdef AP_SUEXEC_UMASK
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* umask() uses inverse logic; bits are CLEAR for allowed access.
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if ((~AP_SUEXEC_UMASK) & 0022) {
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log_err("notice: AP_SUEXEC_UMASK of %03o allows "
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"write permission to group and/or other\n", AP_SUEXEC_UMASK);
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umask(AP_SUEXEC_UMASK);
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#endif /* AP_SUEXEC_UMASK */
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* Be sure to close the log file so the CGI can't
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* mess with it. If the exec fails, it will be reopened
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* automatically when log_err is called. Note that the log
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* might not actually be open if AP_LOG_EXEC isn't defined.
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* However, the "log" cell isn't ifdef'd so let's be defensive
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* and assume someone might have done something with it
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* outside an ifdef'd AP_LOG_EXEC block.
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* Execute the command, replacing our image with its own.
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#ifdef NEED_HASHBANG_EMUL
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/* We need the #! emulation when we want to execute scripts */
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extern char **environ;
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ap_execve(cmd, &argv[3], environ);
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#else /*NEED_HASHBANG_EMUL*/
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execv(cmd, &argv[3]);
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#endif /*NEED_HASHBANG_EMUL*/
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* (I can't help myself...sorry.)
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* Uh oh. Still here. Where's the kaboom? There was supposed to be an
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* EARTH-shattering kaboom!
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* Oh well, log the failure and error out.
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log_err("(%d)%s: exec failed (%s)\n", errno, strerror(errno), cmd);