I created a SuExec Modification, which chroots first to the User-Homedir and 
then executes the cgi-script (kind of "mpm_peruser", but faster on machines 
with low memory)

The Interpreter(s) are needed to be in the jail too, otherwise it can't 
execute the script then.

I created it with httpd 2.0.55, but it should work on other versions too.

It works for example if you have such a directory structure:

/srv/www
/srv/www/vhosts
/srv/www/vhosts/user1
/srv/www/vhosts/user1/htdocs
/srv/www/vhosts/user2
/srv/www/vhosts/user2/htdocs

So a request for "user1" will be chrooted first to /srv/www/vhosts/user1, and 
then it will execute the specified script in that directory.

Sincerely
F. D.

---

diff -urN httpd-2.0.55-orig/support/suexec.c httpd-2.0.55/support/suexec.c
--- httpd-2.0.55-orig/support/suexec.c	2005-02-04 21:21:18.000000000 +0100
+++ httpd-2.0.55/support/suexec.c	2006-01-04 10:02:21.017195966 +0100
@@ -1,34 +1,34 @@
 /* Copyright 1999-2005 The Apache Software Foundation or its licensors, as
- * applicable.
- *
- * Licensed 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.
- */
+* applicable.
+*
+* Licensed 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.
- *
- ***********************************************************************
- *
- *
- */
+* 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 "apr.h"
 #include "ap_config.h"
@@ -55,21 +55,166 @@
 #include <grp.h>
 #endif
 
+
+/**********************/
+/* CHROOT Data, Begin */
+
+#ifdef MAXPATHLEN
+#define PATH_LEN MAXPATHLEN
+#else
+#define PATH_LEN PATH_MAX
+#endif
+
+#define PASSWD_FILE     "/etc/passwd"
+#define LINE_SZ         256
+
+struct passwd_data_s {
+  char *login;
+  char *pass;
+  int  id;
+  int  gid;
+  char *gecos;
+  char *dir;
+  char *shell;
+};
+
+typedef struct passwd_data_s passwd_data;
+
+/**********************/
+
+void free_passwd_data(passwd_data *p) {
+
+  if (p == NULL)
+    return;
+
+  if (p->login!=NULL) free(p->login);
+  if (p->pass!=NULL)  free(p->pass);
+  if (p->gecos!=NULL) free(p->gecos);
+  if (p->dir!=NULL)   free(p->dir);
+  if (p->shell!=NULL) free(p->shell);
+
+  free(p);
+}
+
+int fill_from_string(char *str, passwd_data *data) {
+  char *p = str;
+  char buff[LINE_SZ];
+  int n = 0;
+  int state = 0;
+
+  memset(buff,'\0',LINE_SZ);
+
+  while (*p != '\0') {
+
+    if ((*p == ':') || (*p == '\n')) {
+      switch (state) {
+      case 0: 
+        data->login = (char *)malloc(strlen(buff)+1);
+        memset(data->login,'\0',strlen(buff)+1);
+        strcpy(data->login,buff);
+        break;
+      case 1: 
+        data->pass = (char *)malloc(strlen(buff)+1);
+        memset(data->pass,'\0',strlen(buff)+1);
+        strcpy(data->pass,buff);
+        break;
+      case 2: 
+        data->id = atoi(buff);
+        break;
+      case 3: 
+        data->gid = atoi(buff);
+        break;
+      case 4: 
+        data->gecos = (char *)malloc(strlen(buff)+1);
+        memset(data->gecos,'\0',strlen(buff)+1);
+        strcpy(data->gecos,buff);
+        break;
+      case 5: 
+        data->dir = (char *)malloc(strlen(buff)+1);
+        memset(data->dir,'\0',strlen(buff)+1);
+        strcpy(data->dir,buff);
+        break;
+      case 6: 
+        data->shell = (char *)malloc(strlen(buff)+1);
+        memset(data->shell,'\0',strlen(buff)+1);
+        strncpy(data->shell,buff,strlen(buff));
+        break;
+      }
+
+      memset(buff,'\0',LINE_SZ);
+      n=0;
+      state++;
+    }
+    else {
+      buff[n] = *p;
+      n++;
+    }
+
+    p++;
+  }
+
+  if (state > 6) 
+    return(1);
+
+  return(0);
+}
+
+passwd_data *getpasswddata(int uid) {
+  char line[LINE_SZ];
+  passwd_data *pd = NULL;
+  FILE *f = NULL;
+
+  f = fopen(PASSWD_FILE,"r");
+
+  if (!f) 
+    return(pd);
+
+  while (!feof(f)) {
+
+    memset(line,'\0',LINE_SZ);
+
+    if (fgets(line,LINE_SZ,f)==NULL) {
+      pd = NULL;
+      break;
+    }
+
+    pd = (passwd_data *)malloc(sizeof(passwd_data));
+    memset(pd,'\0',sizeof(passwd_data));
+
+    if (!fill_from_string(line,pd)) {
+      free_passwd_data(pd);
+      continue;
+    }
+
+    if (pd->id == uid) 
+      break;
+
+    free_passwd_data(pd);
+  } 
+
+  fclose(f);
+  return(pd);
+
+};
+
+/* CHROOT Data, End   */
+/**********************/
+
 /*
- ***********************************************************************
- * 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
- ***********************************************************************
- */
+***********************************************************************
+* 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;
+  /* QNX and MPE do not appear to support supplementary groups. */
+  return 0;
 }
 #endif
 
@@ -93,527 +238,583 @@
 
 char *safe_env_lst[] =
 {
-    /* variable name starts with */
-    "HTTP_",
-    "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=",
-    "HTTPS=",
-    "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_REMOTE_USER=",
-    "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_SIGNATURE=",
-    "SERVER_SOFTWARE=",
-    "UNIQUE_ID=",
-    "USER_NAME=",
-    "TZ=",
-    NULL
+  /* variable name starts with */
+  "HTTP_",
+  "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=",
+  "HTTPS=",
+  "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_REMOTE_USER=",
+  "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_SIGNATURE=",
+  "SERVER_SOFTWARE=",
+  "UNIQUE_ID=",
+  "USER_NAME=",
+  "TZ=",
+  NULL
 };
 
 
 static void err_output(const char *fmt, va_list ap)
 {
 #ifdef AP_LOG_EXEC
-    time_t timevar;
-    struct tm *lt;
+  time_t timevar;
+  struct tm *lt;
 
-    if (!log) {
-        if ((log = fopen(AP_LOG_EXEC, "a")) == NULL) {
-            fprintf(stderr, "failed to open log file\n");
-            perror("fopen");
-            exit(1);
-        }
+  if (!log) {
+    if ((log = fopen(AP_LOG_EXEC, "a")) == NULL) {
+      fprintf(stderr, "failed to open log file %s\n",AP_LOG_EXEC);
+      perror("fopen");
+      exit(1);
     }
+  }
 
-    time(&timevar);
-    lt = localtime(&timevar);
+  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);
+  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);
+  vfprintf(log, fmt, ap);
 
-    fflush(log);
+  fflush(log);
 #endif /* AP_LOG_EXEC */
-    return;
+  return;
 }
 
 static void log_err(const char *fmt,...)
 {
 #ifdef AP_LOG_EXEC
-    va_list ap;
+  va_list ap;
 
-    va_start(ap, fmt);
-    err_output(fmt, ap);
-    va_end(ap);
+  va_start(ap, fmt);
+  err_output(fmt, ap);
+  va_end(ap);
 #endif /* AP_LOG_EXEC */
-    return;
+  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("failed to malloc memory for environment\n");
-        exit(120);
-    }
-
-    sprintf(pathbuf, "PATH=%s", AP_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;
-            }
-        }
+  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("failed to malloc memory for environment\n");
+    exit(120);
+  }
+
+  sprintf(pathbuf, "PATH=%s", AP_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;
+  cleanenv[cidx] = NULL;
 
-    environ = cleanenv;
+  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)
+  /**********************/
+  /* CHROOT Vars, Begin */
+  int ret;
+  passwd_data *pwdent;
+  char *tmp_str;
+  /* CHROOT Vars, End   */
+  /**********************/
+
+
+  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(AP_HTTPD_USER, pw->pw_name)))
+    /* User name comparisons are case insensitive on BS2000/OSD */
+    || (! strcasecmp(AP_HTTPD_USER, pw->pw_name)))
 #else  /* _OSD_POSIX */
-            || (! strcmp(AP_HTTPD_USER, pw->pw_name)))
+    || (! strcmp(AP_HTTPD_USER, pw->pw_name)))
 #endif /* _OSD_POSIX */
-        ) {
+    ) {
 #ifdef AP_DOC_ROOT
-        fprintf(stderr, " -D AP_DOC_ROOT=\"%s\"\n", AP_DOC_ROOT);
+      fprintf(stderr, " -D AP_DOC_ROOT=\"%s\"\n", AP_DOC_ROOT);
 #endif
 #ifdef AP_GID_MIN
-        fprintf(stderr, " -D AP_GID_MIN=%d\n", AP_GID_MIN);
+      fprintf(stderr, " -D AP_GID_MIN=%d\n", AP_GID_MIN);
 #endif
 #ifdef AP_HTTPD_USER
-        fprintf(stderr, " -D AP_HTTPD_USER=\"%s\"\n", AP_HTTPD_USER);
+      fprintf(stderr, " -D AP_HTTPD_USER=\"%s\"\n", AP_HTTPD_USER);
 #endif
 #ifdef AP_LOG_EXEC
-        fprintf(stderr, " -D AP_LOG_EXEC=\"%s\"\n", AP_LOG_EXEC);
+      fprintf(stderr, " -D AP_LOG_EXEC=\"%s\"\n", AP_LOG_EXEC);
 #endif
 #ifdef AP_SAFE_PATH
-        fprintf(stderr, " -D AP_SAFE_PATH=\"%s\"\n", AP_SAFE_PATH);
+      fprintf(stderr, " -D AP_SAFE_PATH=\"%s\"\n", AP_SAFE_PATH);
 #endif
 #ifdef AP_SUEXEC_UMASK
-        fprintf(stderr, " -D AP_SUEXEC_UMASK=%03o\n", AP_SUEXEC_UMASK);
+      fprintf(stderr, " -D AP_SUEXEC_UMASK=%03o\n", AP_SUEXEC_UMASK);
 #endif
 #ifdef AP_UID_MIN
-        fprintf(stderr, " -D AP_UID_MIN=%d\n", AP_UID_MIN);
+      fprintf(stderr, " -D AP_UID_MIN=%d\n", AP_UID_MIN);
 #endif
 #ifdef AP_USERDIR_SUFFIX
-        fprintf(stderr, " -D AP_USERDIR_SUFFIX=\"%s\"\n", AP_USERDIR_SUFFIX);
+      fprintf(stderr, " -D AP_USERDIR_SUFFIX=\"%s\"\n", AP_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("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.
-     */
+      exit(0);
+  }
+  /*
+  * If there are a proper number of arguments, set
+  * all of them to variables.  Otherwise, error out.
+  */
+  if (argc < 4) {
+    log_err("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(AP_HTTPD_USER, pw->pw_name)) {
-        log_err("user mismatch (%s instead of %s)\n", pw->pw_name, 
AP_HTTPD_USER);
-        exit(103);
-    }
+  /* User name comparisons are case insensitive on BS2000/OSD */
+  if (strcasecmp(AP_HTTPD_USER, pw->pw_name)) {
+    log_err("user mismatch (%s instead of %s)\n", pw->pw_name, AP_HTTPD_USER);
+    exit(103);
+  }
 #else  /*_OSD_POSIX*/
-    if (strcmp(AP_HTTPD_USER, pw->pw_name)) {
-        log_err("user mismatch (%s instead of %s)\n", pw->pw_name, 
AP_HTTPD_USER);
-        exit(103);
-    }
+  if (strcmp(AP_HTTPD_USER, pw->pw_name)) {
+    log_err("user mismatch (%s instead of %s)\n", pw->pw_name, AP_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("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 (strspn(target_uname, "1234567890") != strlen(target_uname)) {
-        if ((pw = getpwnam(target_uname)) == NULL) {
-            log_err("invalid target user name: (%s)\n", target_uname);
-            exit(105);
-        }
-    }
-    else {
-        if ((pw = getpwuid(atoi(target_uname))) == NULL) {
-            log_err("invalid target user id: (%s)\n", target_uname);
-            exit(121);
-        }
-    }
-
-    /*
-     * 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);
-    }
+  /*
+  * 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 (strspn(target_uname, "1234567890") != strlen(target_uname)) {
+    if ((pw = getpwnam(target_uname)) == NULL) {
+      log_err("invalid target user name: (%s)\n", target_uname);
+      exit(105);
+    }
+  }
+  else {
+    if ((pw = getpwuid(atoi(target_uname))) == NULL) {
+      log_err("invalid target user id: (%s)\n", target_uname);
+      exit(121);
+    }
+  }
+
+  /*
+  * 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);
+  }
 
 #ifdef _OSD_POSIX
-    /*
-     * Initialize BS2000 user environment
-     */
-    {
-        pid_t pid;
-        int status;
-
-        switch (pid = ufork(target_uname)) {
-        case -1:    /* Error */
-            log_err("failed to setup bs2000 environment for user %s: %s\n",
-                    target_uname, strerror(errno));
-            exit(150);
-        case 0:     /* Child */
-            break;
-        default:    /* Father */
-            while (pid != waitpid(pid, &status, 0))
-                ;
-            /* @@@ FIXME: should we deal with STOP signals as well? */
-            if (WIFSIGNALED(status)) {
-                kill (getpid(), WTERMSIG(status));
-            }
-            exit(WEXITSTATUS(status));
-        }
+  /*
+  * Initialize BS2000 user environment
+  */
+  {
+    pid_t pid;
+    int status;
+
+    switch (pid = ufork(target_uname)) {
+  case -1:    /* Error */
+    log_err("failed to setup bs2000 environment for user %s: %s\n",
+      target_uname, strerror(errno));
+    exit(150);
+  case 0:     /* Child */
+    break;
+  default:    /* Father */
+    while (pid != waitpid(pid, &status, 0))
+      ;
+    /* @@@ FIXME: should we deal with STOP signals as well? */
+    if (WIFSIGNALED(status)) {
+      kill (getpid(), WTERMSIG(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("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 AP_UID_MIN.  Tsk tsk.
-     */
-    if ((uid == 0) || (uid < AP_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 AP_GID_MIN.  Tsk tsk.
-     */
-    if ((gid == 0) || (gid < AP_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)\n", gid, cmd);
-        exit(109);
-    }
-
-    /*
-     * setuid() to the target user.  Error out on fail.
-     */
-    if ((setuid(uid)) != 0) {
-        log_err("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("cannot get current working directory\n");
-        exit(111);
-    }
-
-    if (userdir) {
-        if (((chdir(target_homedir)) != 0) ||
-            ((chdir(AP_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(AP_DOC_ROOT)) != 0) ||
-            ((getcwd(dwd, AP_MAXPATH)) == NULL) ||
-            ((chdir(cwd)) != 0)) {
-            log_err("cannot get docroot information (%s)\n", AP_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);
-    }
-    /*
-     * 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("file has no execute permission: (%s/%s)\n", cwd, cmd);
-        exit(121);
+    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("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 AP_UID_MIN.  Tsk tsk.
+  */
+  if ((uid == 0) || (uid < AP_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 AP_GID_MIN.  Tsk tsk.
+  */
+  if ((gid == 0) || (gid < AP_GID_MIN)) {
+    log_err("cannot run as forbidden gid (%d/%s)\n", gid, cmd);
+    exit(108);
+  }
+
+  /********************************/
+  /* CHROOT Implementation, Begin */
+
+  /* First, we have to be root */
+  if (setgid(0) || setuid(0) || getuid() != geteuid() || getgid() != getegid
()) {
+    log_err("suexec: can't setgid(0). (Is suexec owned by root and has setuid 
permissions?)\n");
+    exit(126);
+  }
+
+  /* Now, read the userdata of the specified user */
+  pwdent = getpasswddata(uid);
+  if (pwdent == NULL) {
+    log_err("suexec: can't get passwd info for uid %d\n",uid);
+    exit(122);
+  }
+
+  /* Get Full-Path of the user-homedir */
+  tmp_str = (char *)malloc(PATH_LEN);
+  if (!realpath(pwdent->dir,tmp_str)) {
+    log_err("suexec: can't canonize path \"%s\". Bad path?\n", pwdent->dir);
+    exit(123);
+  }
+  free(pwdent->dir);
+  pwdent->dir = tmp_str;
+
+  /* We have to read the current directory here, won't work after chroot */
+  if (getcwd(cwd, AP_MAXPATH) == NULL) {
+    log_err("cannot get current working directory\n");
+    exit(111);
+  }
+
+  /* Changing to Home-Dir of user */
+  ret = chdir(pwdent->dir);	
+  if (ret) {
+    log_err("suexec: can't chdir to path \"%s\". Bad path?\n", pwdent->dir);
+    exit(124);
+  }
+
+  /* Now we change the root */
+  ret = chroot(pwdent->dir);
+  if (ret) { 
+    log_err("suexec: can't chroot to path \"%s\"\n", pwdent->dir);
+    exit(125);
+  }
+
+  /*
+  * 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)\n", gid, cmd);
+    exit(109);
+  }
+
+  /*
+  * setuid() to the target user.  Error out on fail.
+  */
+  if ((setuid(uid)) != 0) {
+    log_err("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 (userdir) {
+    if (((chdir(target_homedir)) != 0) ||
+      ((chdir(AP_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(AP_DOC_ROOT)) != 0) ||
+      ((getcwd(dwd, AP_MAXPATH)) == NULL) ||
+      ((chdir(cwd)) != 0)) {
+        log_err("cannot get docroot information (%s)\n", AP_DOC_ROOT);
+        exit(113);
+    }
+  }
+
+  if ((strncmp(cwd, dwd, strlen(dwd))) != 0) {
+    log_err("command not in docroot (%s - %s - %s)\n", cwd, cmd, dwd);
+    exit(114);
+  }
+
+  /* free the password-data */
+  free_passwd_data(pwdent);
+
+  /* CHROOT Implementation, End   */
+  /********************************/
+  
+  /*
+  * 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);
+  }
+  /*
+  * 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("file has no execute permission: (%s/%s)\n", cwd, cmd);
+    exit(121);
+  }
 
 #ifdef AP_SUEXEC_UMASK
-    /*
-     * umask() uses inverse logic; bits are CLEAR for allowed access.
-     */
-    if ((~AP_SUEXEC_UMASK) & 0022) {
-        log_err("notice: AP_SUEXEC_UMASK of %03o allows "
-                "write permission to group and/or other\n", AP_SUEXEC_UMASK);
-    }
-    umask(AP_SUEXEC_UMASK);
+  /*
+  * umask() uses inverse logic; bits are CLEAR for allowed access.
+  */
+  if ((~AP_SUEXEC_UMASK) & 0022) {
+    log_err("notice: AP_SUEXEC_UMASK of %03o allows "
+      "write permission to group and/or other\n", AP_SUEXEC_UMASK);
+  }
+  umask(AP_SUEXEC_UMASK);
 #endif /* AP_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 AP_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 AP_LOG_EXEC block.
-     */
-    if (log != NULL) {
-        fclose(log);
-        log = NULL;
-    }
-
-    /*
-     * Execute the command, replacing our image with its own.
-     */
+  /* 
+  * 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 AP_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 AP_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;
+  /* We need the #! emulation when we want to execute scripts */
+  {
+    extern char **environ;
 
-        ap_execve(cmd, &argv[3], environ);
-    }
+    ap_execve(cmd, &argv[3], environ);
+  }
 #else /*NEED_HASHBANG_EMUL*/
-    execv(cmd, &argv[3]);
+  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("(%d)%s: exec failed (%s)\n", errno, strerror(errno), cmd);
-    exit(255);
+  /*
+  * (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("(%d)%s: exec failed (%s)\n", errno, strerror(errno), cmd);
+  exit(255);
 }