Differences

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--- linux:grsec [2006/07/26 14:23]
a
+++ linux:grsec [2009/05/25 00:35] (current)
@@ Line 41: / Line 41: @@
 ==== kernel 2.4.x tips ====
 ==== kernel 2.6.x tips ====
+=== What to include in 2.6 with GRSecurity (Safeway) ===
+**taken from: [[http://lists.grok.org.uk/pipermail/full-disclosure/2003-August/008236.htm|here]]
+**
+There are some problems with some applications with parts of the patch. For
+example, turning on the non-executeable stack will break anything that uses
+an executeable stack. ie: X, java, or wine, now you can use chpax and give
+each of these a non executable stack. There are also some problems with the
+way grsecurity gets a little to restrictive with things like restericting
+filesystems ect. All of these can be overcome, however, you need to do some
+magic to get some of these things to work, and frankly, some of it really
+isnt worth it.
+There are several options inside the grsecurity patch that you can choose.
+What you can safely turn on in GRsecurity without breaking anything is:
+   * **''Address Space Protection''**
+   * **''Address Space Layout Randomization''**
+      * **''Randomize kernel stack base''**
+      * **''Randomize user stack base''**
+      * **''Randomize mmap() base''**
+   * **Filesystem Protections**
+      * //Everything under this option is safe to include//
+   * **''Kernel Auditing''**
+      * //Everything under this option is safe to include//
+   * **''Executable Protections''**
+      * //Everything under this option is safe to __incude except__:// ''Partially restrict non-root users''
+  * **''Network Protections''**
+     * //Everything under this option is safe to include//
+  * **''Sysctl support''** //This is usefull to enable, but not necesary
+//
+Compile everything staticly and you shold be fine.
+I have tested this on production servers, and desktop boxes in mass and its
+come out fine for x86 and sparc. I havent tried it on ppc but for the most
+part it is safe, and it is also safe for production envoirnments.
+=== Using Pax and Grsecurity features ===
+First get a grsecurity patch kernel ready go in your **''menuconfig > Security > Pax Funnctions''**
+<code>
+Enable various PaX features
+[*] Support soft mode
+[*] Use legacy ELF header marking
+[*] Use ELF program header marking
+MAC system integration (direct)  —>
+Non-executable pages
+[*] Enforce non-executable pages
+[*]   Paging based non-executable pages
+[*]   Segmentation based non-executable pages
+[*] Emulate trampolines
+[*] Restrict mprotect()
+[ ]   Disallow ELF text relocations
+[*] Enforce non-executable kernel pages
+[*] Address Space Layout Randomization
+[*]   Randomize kernel stack base
+[*]   Randomize user stack base
+[*]   Randomize mmap() base
+</code>
+And for Miscellaneous hardening features I advise not to select any.
+<note important>Once you got your pax and gr security kernel setup and have booted into it the first thing you will have to do is disable some pax functions on php binaries. **NOTICE: php will work with pax functions enabled but will nbot be able to load anything like zend optimizer**</note>
 ===== Configuration =====
@@ Line 86: / Line 163: @@
   kernel.pax.softmode = 1
   kernel.grsecurity.grsec_lock = 0
 ==== PaX ====
@@ Line 129: / Line 207: @@
   Executable shared library data           : Vulnerable
   Writable text segments                   : Vulnerable
+==== Hardening Webservers ====
+For example
+   paxctl -c /usr/local/bin/php
+   paxctl -permxs /usr/local/bin/php
+You can even use wildcards like'' /usr/bin/php*''
+Also make sure you do the** ''sapi/cli/cgi''** module of your web server the same way. On some webservers like litespeed you will have to do the binaries on it as well. Do not disable binaries too freely, only try to do it if it is the only option to make it work.
 ==== gdadm ====
@@ Line 159: / Line 249: @@
    gradm -D
 ==== grsec iptables patch ====
 FIXME TODO
+===== Tips / troubleshooting =====
+==== complaints of grsecurity-kernel about RLIMIT_CORE being 0 ====
+If, while running program x, a segmentation fault occurs in program x and syslog outputs the following string:
+   Apr 17 11:55:06 yyy kernel: grsec: attempted resource overstep by requesting 4096 for RLIMIT_CORE against limit 0 by (x:z) UID(y) EUID(y), parent (y:y) UID(y) EUID(y)
+then kernel tried to write a core-file for the program x to disk, BUT the max size of the core file is set to 0.
+Growing the maximum size of a core file:
+  # ulimit -S -c 8192