chroot - Change Root

I have recently closed a year old ticket that has some thing to do with chroot. For security reason, we use chroot (in modsecurity) to restrict our Apache process to access only to a desired directory tree. As per chroot document, a program that is re-rooted to another directory cannot access or name files outside that directory, and the directory is called a "chroot jail".
We make sure that chroot is called after Apache process complete it' initialization in order to not break anything, Because otherwise Apache will not be able to access needed share lib, log files, pid file located in various system directories.
However there is a wrong access time the log produced by our Apache. It is always GMT not local time as we want. We have opened ticket with vendor, searching over internet, looking at source code but could not figure out why. The worse thing is that, for first few requests , the access time is correct (local time) but then it gets change to GMT.
Yesterday I have found the reason. I remember that when I ran the strace with the Apache process being chrooted, I saw Apache try to open some files but could not find it. We see a lot of file not found when running strace because various libraries intend to open some file and if it is not found then try others. But in that case the file is /etc/localtime. So it turns out that when logging Apache use apr lib, which call gmtime and mktime, which need to access /etc/localtime. So missing this file in "chroot jail" causes a problem with access time. Without file /etc/localtime gmtime and mktime consider that the machine is in GMT time zone.

Using debuginfo packages in Redhat

Redhat provide debuginfo packages but not tell us so much how to use it. Here is a simple instruction to use debuginfo packages.
First this is important to know that a debuginfo package contains only debug symbol not the executable. Therefore we need to install both normal package and the corresponding debuginfo and of course their version must be matched.
Installation
Make sure that repository of debuginfo package is configured properly as follows

[root@localhost ~]# cat /etc/yum.repos.d/rhel-debuginfo.repo 
[rhel-debuginfo]
name=Red Hat Enterprise Linux $releasever - $basearch - Debug
baseurl=ftp://ftp.redhat.com/pub/redhat/linux/enterprise/$releasever/en/os/$basearch/Debuginfo/
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release

To install debuginfo package, we have to specify --enablerepo rhel-debuginfo as yum option

root@localhost ~]#yum install --enablerepo rhel-debuginfo httpd-debuginfo

root@localhost ~]#yum install httpd

[root@localhost ~]# rpm -q -a | grep httpd
httpd-debuginfo-2.2.3-43.el5_5.3
httpd-2.2.3-43.el5_5.3

Usage
To get use just start gdb session with a normal executable

[root@localhost ~]# gdb /usr/bin/ab
GNU gdb (GDB) Red Hat Enterprise Linux (7.0.1-23.el5_5.2)
Copyright (C) 2009 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later 
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "i386-redhat-linux-gnu".
For bug reporting instructions, please see:
...
Reading symbols from /usr/bin/ab...Reading symbols from /usr/lib/debug/usr/bin/ab.debug...done.
done.
(gdb) break main
Breakpoint 1 at 0x7402: file /usr/src/debug/httpd-2.2.3/support/ab.c, line 1900.
(gdb) run
Starting program: /usr/bin/ab 
[Thread debugging using libthread_db enabled]

Breakpoint 1, main (argc=114424, argv=0x0) at /usr/src/debug/httpd-2.2.3/support/ab.c:1900
1900 {
(gdb) l
1895 
1896 /* ------------------------------------------------------- */
1897 
1898 /* sort out command-line args and call test */
1899 int main(int argc, const char * const argv[])
1900 {
1901     int r, l;
1902     char tmp[1024];
1903     apr_status_t status;
1904     apr_getopt_t *opt;
(gdb) 

Where to download RPM package(s) for RedHat Linux

If you are looking for RPM package(s) for LINUX, then you should look at this site http://linuxsoft.cern.ch/. The binary rpm package are built from source SRPM available in http://ftp.redhat.com/pub/redhat/linux/enterprise/. They are well organized, complete and updated. The slc4X directory is equivalent to RedHat ES/AS 4 while slc5X to RedHat ES/AS 5.
If you have not RedHat Linux media in hand for what ever reason, this is definitely a good help.