PROPOLICE FOR FREEBSD

This patch implements the work of Hiroaki Etoh into FreeBSD 5.4 and 6.0.
See http://www.trl.ibm.com/projects/security/ssp/ or Wikipedia for details

Propolice is also known as Stack-Smashing Protector (SSP)

Update 12 nov 2006: tested and confirmed to work on FreeBSD 6.1-RELEASE and FreeBSD 6.2-PRERELEASE.

For info comments questions and feedback about this patch, mail to Thijs Eilander (nomad at paranoid dot nl)

downloads:

The patch contains the following parts:

• GCC Patches from IBM
• FreeBSD libc/libkern additions, also some changes to Makefiles
• Introducing the new sysctl kern.arnd, for filling the canary

How to use:

1. Get source of FreeBSD 5.4-RELEASE or FreeBSD 6.0-RELEASE

2. download and apply the propolice patch.
   
   cd /usr/src
   patch -p0 < propolice-fbsd54-2.diff
   

3. cp /usr/src/sys/sys/sysctl.h /usr/include/sys/sysctl.h
(this is neccesary)
4. build and install libc
   
   cd /usr/src/lib/libc
   make obj && make depend && make all install
   

5. build and install gcc
   
   cd /usr/src/gnu/usr.bin/cc
   make obj && make depend && make all install
6. Recompile everything:
   
   A) Build new kernel (neccessary!)
       cd /usr/src && make buildkernel && make installkernel && reboot
   B) Build new world (recommended)
       cd /usr/src && make buildworld && make installworld
   C) rebuild applications (recommended)

7. Congratulations., your system is now propolice-enabled.
   
   $ gcc -v
   Using built-in specs.
   Configured with: FreeBSD/i386 system compiler
   Thread model: posix gcc version 3.4.2 [FreeBSD] 20040728 (propolice)
   
   You can test the stackprotector with propolice-test.c :
   
   $ gcc -o ptest propolice-test.c
   $ ./ptest
   Abort (core dumped)
   $ tail -2 /var/log/messages
   Apr 23 15:55:34 devel ptest: stack overflow in function main
   Apr 23 15:55:34 devel kernel: pid 17722 (ptest), uid 0: exited on signal 6 (core dumped)
   
   SSP gives the program a kill SIGABORT (signal 6).
   An executable is protected when you see __stack_smash_handler with strings. (Such executable will NOT run on a system without SSP in LIBC)
   
   $ strings a.out | grep smash
   __stack_smash_handler
   
   
   

NOTE: The executables will only be protected when compiled with a propolice-gcc so dont use precompiled packages/distributions. Use ports or source only !

NOTE: don't upgrade/downgrade libc (that includes a new world) without an (dummy) SSP handler in it. Programs compiled with propolice won't run on a libc without propolice. YOU WILL BREAK THINGS.

LINKS:
GCC extension for protecting applications from stack-smashing attacks
Wikipedia
How to patch Solaris
Interview with an openbsd developper (search for propolice)
OpenBSD: Stack-Smashing Protection
Jeremie Le-Hen's propolice implementation for FreeBSD 6.0


Author of this patch&page;: Thijs Eilander (nomad at paranoid dot nl)
Updated: Nov 12 2006 / tested on FreeBSD 6.1 and 6.2
Updated: Apr 23 2005 / Initial patch
Updated: May 25 2005 / documentation + md5 strings
Updated: Okt 24 2005 / Adding patch for FreeBSD 6.0