From 5dff830dc201fb5a1927aee293f3fc62ccf09a22 Mon Sep 17 00:00:00 2001 From: klondike Date: Sat, 28 Apr 2012 21:15:34 +0200 Subject: Update previews --- html/revdep-pax.html | 551 ++------------------------------ html/roadmap.html | 22 +- html/selinux-faq.html | 27 +- html/selinux/hb-using-install.html | 18 +- html/selinux/hb-using-troubleshoot.html | 27 +- 5 files changed, 106 insertions(+), 539 deletions(-) (limited to 'html') diff --git a/html/revdep-pax.html b/html/revdep-pax.html index ee4e6d4..accbeee 100644 --- a/html/revdep-pax.html +++ b/html/revdep-pax.html @@ -21,13 +21,18 @@
Content: +

1. What's revdep-pax about?

-

A quick introduction to PaX markings.

+

+Since the early days of PaX it was known that all programs were equal although +some were more equal than others and needed an environment with less +restrictions in order to be able to run. Thus, in order to have a secure way of +allowing system administrators and users telling the system which binaries +needed this lessened environment the PaX marks were created. +

—Geroge Orwell

+

A quick introduction to PaX markings.

There are some programs which won't be able to run in an environment with all the PaX features enabled, for example you may have a program which has so called @@ -88,7 +93,7 @@ marks to the library to state it needs trampoline emulation but still we haven't fixed the issue since the kernel will only read the marks on the binary being called. In order to solve this issue we have created revdep-pax.

-

What's revdep-pax?

+

What's revdep-pax?

revdep-pax is a tool that allows to check for differences in PaX markings between elf objects linking to libraries (for example /bin/bash) @@ -108,530 +113,42 @@ libraries linked by an object and backwards to the objects linked by a library.

2. Using revdep-pax

-

Propagating PaX marks backwards from a library to objects that link at it +

+In order to witness the firepower of this fully ARMED and OPERATIONAL tool +you'll first need to learn how to use it, once you are done, you'll be +able to fire at will. +

—The Emperor

+

Propagating PaX marks backwards from a library to objects that link at it

This is going to be probably the main way in which you are going to use this -utility. What it does is check all the libraries linked statically -The scanelf application is part of the app-misc/pax-utils package. -With this application you can print out information specific to the ELF -structure of a binary. The following table sums up the various options. -

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
OptionLong OptionDescription
-p--pathScan all directories in PATH environment
-l--ldpathScan all directories in /etc/ld.so.conf
-R--recursiveScan directories recursively
-m--mountDon't recursively cross mount points
-y--symlinkDon't scan symlinks
-A--archivesScan archives (.a files)
-L--ldcacheUtilize ld.so.cache information (use with -r/-n)
-X--fixTry and 'fix' bad things (use with -r/-e)
-z [arg]--setpax [arg]Sets EI_PAX/PT_PAX_FLAGS to [arg] (use with -Xx)
OptionLong OptionDescription
-x--paxPrint PaX markings
-e--headerPrint GNU_STACK/PT_LOAD markings
-t--textrelPrint TEXTREL information
-r--rpathPrint RPATH information
-n--neededPrint NEEDED information
-i--interpPrint INTERP information
-b--bindPrint BIND information
-S--sonamePrint SONAME information
-s [arg]--symbol [arg]Find a specified symbol
-k [arg]--section [arg]Find a specified section
-N [arg]--lib [arg]Find a specified library
-g--gmatchUse strncmp to match libraries. (use with -N)
-T--textrelsLocate cause of TEXTREL
-E [arg]--etype [arg]Print only ELF files matching etype ET_DYN,ET_EXEC ...
-M [arg]--bits [arg]Print only ELF files matching numeric bits
-a--allPrint all scanned info (-x -e -t -r -b)
OptionLong OptionDescription
-q--quietOnly output 'bad' things
-v--verboseBe verbose (can be specified more than once)
-F [arg]--format [arg]Use specified format for output
-f [arg]--from [arg]Read input stream from a filename
-o [arg]--file [arg]Write output stream to a filename
-B--nobannerDon't display the header
-h--helpPrint this help and exit
-V--versionPrint version and exit
-

-The format specifiers for the -F option are given in the following table. -Prefix each specifier with % (verbose) or # (silent) accordingly. -

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
SpecifierFull NameSpecifierFull Name
FFilenamexPaX Flags
eSTACK/RELROtTEXTREL
rRPATHnNEEDED
iINTERPbBIND
sSymbolNLibrary
oTypepFile name
fBase file namekSection
aARCH/e_machine
-

Using scanelf for Text Relocations

-

-As an example, we will use scanelf to find binaries containing text -relocations. -

-

-A relocation is an operation that rewrites an address in a loaded segment. Such -an address rewrite can happen when a segment has references to a shared object -and that shared object is loaded in memory. In this case, the references are -substituted with the real address values. Similar events can occur inside the -shared object itself. -

-

-A text relocation is a relocation in the text segment. Since text segments -contain executable code, system administrators might prefer not to have these -segments writable. This is perfectly possible, but since text relocations -actually write in the text segment, it is not always feasible. -

-

-If you want to eliminate text relocations, you will need to make sure -that the application and shared object is built with Position Independent -Code (PIC), making references obsolete. This not only increases security, -but also increases the performance in case of shared objects (allowing writes in -the text segment requires a swap space reservation and a private copy of the -shared object for each application that uses it). -

-

-The following example will search your library paths recursively, without -leaving the mounted file system and ignoring symbolic links, for any ELF binary -containing a text relocation: +utility. What it does is check all the libraries linked statically by the +binaries using ldd and then smartly add the paxmarks of those libraries +to generate the new set. As a result if /usr/games/bin/armagetronad +links with /usr/lib64/libGL.so.1 which has the -m PaX mark +(allow RWX mappings) because you are using a llvm requiring graphics driver +you'll get that binary marked with the -m PaX mark too since it needs it. +Below you can see how to run it.

- +

Code Listing2.1: Scanning the system for text relocation binaries

Code Listing2.1: Propagating the PaX marks from the libraries

-# scanelf -lqtmyR
+# mv /etc/grsec/learning.roles /etc/grsec/policy
+# chmod 0600 /etc/grsec/policy
-

-If you want to scan your entire system for any file containing text -relocations: -

- - - -

Code Listing2.2: Scanning the entire system for text relocation files

-# scanelf -qtmyR /
-
-

Using scanelf for Specific Header

-

-The scanelf util can be used to quickly identify files that contain a -given section header using the -k .section option. -

-

-In this example we are looking for all files in /usr/lib/debug -recursively using a format modifier with quiet mode enabled that have been -stripped. A stripped elf will lack a .symtab entry, so we use the '!' -to invert the matching logic. -

- - - -

Code Listing2.3: Scanning for stripped or non stripped executables

-# scanelf -k '!.symtab' /usr/lib/debug -Rq -F%F#k
-
-

Using scanelf for Specific Segment Markings

-

-Each segment has specific flags assigned to it in the Program Header of the -binary. One of those flags is the type of the segment. Interesting values are -PT_LOAD (the segment must be loaded in memory from file), PT_DYNAMIC (the -segment contains dynamic linking information), PT_INTERP (the segment -contains the name of the program interpreter), PT_GNU_STACK (a GNU extension -for the ELF format, used by some stack protection mechanisms), and PT_PAX_FLAGS -(a PaX extension for the ELF format, used by the security-minded -PaX Project. -

-

-If we want to scan all executables in the current working directory, PATH -environment and library paths and report those who have a writable and -executable PT_LOAD or PT_GNU_STACK marking, you could use the following command: -

- - - -

Code Listing2.4: Scanning for Write/eXecute flags for PT_LOAD and PT_GNU_STACK

-# scanelf -lpqe .
-
-

Using scanelf's Format Modifier Handler

-

-A useful feature of the scanelf utility is the format modifier handler. -With this option you can control the output of scanelf, thereby -simplifying parsing the output with scripts. -

-

-As an example, we will use scanelf to print the file names that contain -text relocations: -

- - - -

Code Listing2.5: Example of the scanelf format modifier handler

-# scanelf -l -p -R -q -F "%F #t"
-
-

3. - Listing PaX Flags and Capabilities

-

About PaX

-

-PaX is a project hosted by the grsecurity project. Quoting the PaX documentation, its main -goal is "to research various defense mechanisms against the exploitation of -software bugs that give an attacker arbitrary read/write access to the -attacked task's address space. This class of bugs contains among others -various forms of buffer overflow bugs (be they stack or heap based), user -supplied format string bugs, etc." -

-

-To be able to benefit from these defense mechanisms, you need to run a Linux -kernel patched with the latest PaX code. The Hardened Gentoo project supports PaX and -its parent project, grsecurity. The supported kernel package is -sys-kernel/hardened-sources. -

-

-The Gentoo/Hardened project has a Gentoo PaX Quickstart Guide -for your reading pleasure. -

-

Flags and Capabilities

-

-If your toolchain supports it, your binaries can have additional PaX flags in -their Program Header. The following flags are supported: -

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
FlagNameDescription
PPAGEEXEC - Refuse code execution on writable pages based on the NX bit - (or emulated NX bit) -
SSEGMEXEC - Refuse code execution on writable pages based on the - segmentation logic of IA-32 -
EEMUTRAMP - Allow known code execution sequences on writable pages that - should not cause any harm -
MMPROTECT - Prevent the creation of new executable code to the process - address space -
RRANDMMAP - Randomize the stack base to prevent certain stack overflow - attacks from being successful -
XRANDEXEC - Randomize the address where the application maps to prevent - certain attacks from being exploitable -
-

-The default Linux kernel also supports certain capabilities, grouped in the -so-called POSIX.1e Capabilities. You can find a listing of those -capabilities in our POSIX Capabilities document. -

-

Using pspax

-

-The pspax application, part of the pax-utils package, displays the -run-time capabilities of all programs you have permission for. On Linux kernels -with additional support for extended attributes (such as SELinux) those -attributes are shown as well. -

-

-When ran, pspax shows the following information: -

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
ColumnDescription
USEROwner of the process
PIDProcess id
PAXRun-time PaX flags (if applicable)
MAPSWrite/eXecute markings for the process map
ELF_TYPEProcess executable type: ET_DYN or ET_EXEC
NAMEName of the process
CAPSPOSIX.1e capabilities (see note)
ATTRExtended attributes (if applicable)

Note: -pspax only displays these capabilities when it is linked with -the external capabilities library. This requires you to build pax-utils -with -DWANT_SYSCAP. +Due to the way in which ldd works you'll get all the libraries required +at runtime, even those required by libraries you link to (and so on recursively) +as a result revdep-pax will detect all dependencies in a single pass. If +the behaviour of ldd changes so may change the behaviour of +revdep-pax

-By default, pspax does not show any kernel processes. If you want those -to be taken as well, use the -a switch. -

-

4. - Programming with ELF files

-

The dumpelf Utility

-

-With the dumpelf utility you can convert a ELF file into human readable C -code that defines a structure with the same image as the original ELF file. +The scanelf application is part of the app-misc/pax-utils package. +With this application you can print out information specific to the ELF +structure of a binary. The following table sums up the various options.

- - - -

Code Listing4.1: dumpelf example

-$ dumpelf /bin/hostname
-#include <elf.h>
-
-/*
- * ELF dump of '/bin/hostname'
- *     10276 (0x2824) bytes
- */
-
-struct {
-        Elf32_Ehdr ehdr;
-        Elf32_Phdr phdrs[8];
-        Elf32_Shdr shdrs[26];
-} dumpedelf_0 = {
-
-.ehdr = {
-(... Output stripped ...)
-

The contents of this document, unless otherwise expressly stated, are licensed under the CC-BY-SA-2.5 license. The Gentoo Name and Logo Usage Guidelines apply.

diff --git a/html/roadmap.html b/html/roadmap.html index 17be1a3..e35467e 100644 --- a/html/roadmap.html +++ b/html/roadmap.html @@ -270,29 +270,15 @@ of the packages and standard policies. Related Bugs - Deprecate old policies - 2011-11-10 - done - SwifT - - - - Deprecate old profiles - 2011-12-01 - done - blueness - - - - Get mainstream packages the proper dependencies on the SELinux policies - 2011-12-31 + Stabilize 20120215 policies + 2012-04-30 SwifT Have SELinux-enabled stage3 available on the mirrors - 2012-01-31 + 2012-06-31 @@ -302,7 +288,7 @@ of the packages and standard policies. - +

Print

Page updated December 10, 2011

Page updated April 5, 2012

Summary: A roadmap that plots current needs and goals of the Hardened Gentoo project. diff --git a/html/selinux-faq.html b/html/selinux-faq.html index 41695b4..29c7826 100644 --- a/html/selinux-faq.html +++ b/html/selinux-faq.html @@ -79,6 +79,7 @@ FAILED (crontabs/root)'

  • Applications do not transition on a nosuid-mounted partition
  • Why do I always need to re-authenticate when operating init scripts?
  • How do I use SELinux with initramfs?
    • +
  • Logons through xdm (or similar) fail

    • 2. General SELinux Support Questions

    @@ -728,11 +729,35 @@ When enabled, enforcing mode cannot be disabled anymore (until you reboot). # setsebool secure_mode_policyload on
    +

    Logons through xdm (or similar) fail

    +

    +If you log on through xdm, gdm, kdm, slim or any other graphical logon manager, +you might notice in permissive mode that your context is off, and in enforcing +mode that you just cannot log on. +

    +

    +The reason of this is that PAM needs to be configured to include SELinux +awareness in your session handling: +

    + + + +

    Code Listing5.18: Updating pam setting for gdm

    +...
+session  required   pam_loginuid.so
+session  optional   pam_console.so
+session  optional   pam_selinux.so
+
    +

    +Replicate the calls towards pam_selinux.so in the various +/etc/pam.d/gdm* files (or similar depending on your graphical +logon manager). +



    - +

    Print

    Page updated February 26, 2012

    Page updated April 5, 2012

    Summary: Frequently Asked Questions on SELinux integration with Gentoo Hardened. The FAQ is a collection of solutions found on IRC, mailinglist, forums or diff --git a/html/selinux/hb-using-install.html b/html/selinux/hb-using-install.html index fc61177..9e97553 100644 --- a/html/selinux/hb-using-install.html +++ b/html/selinux/hb-using-install.html @@ -58,6 +58,7 @@ we recommend to switch to Python 2 until the packages are updated and fixed.

    Code Listing1.1: Switching to python 2

    +~# emerge '<=dev-lang/python-3.0'
 ~# eselect python list
 Available Python interpreters:
   [1]   python2.7
@@ -184,6 +185,7 @@ The following changes might be necessary on your s
 tools or configurations that apply.
 
    
 
      
+  
   
    • 
     If you use LVM for one or more file systems, you need to edit
     /lib/rcscripts/addons/lvm-start.sh (or /lib64/..)
@@ -200,6 +202,12 @@ tools or configurations that apply.
     which mess up the file labelling. For instance, cp /bin/hostname 
     /bin/hostname.old.
   
      • 
+  
+  
    • 
+    Edit /etc/sandbox.conf and add in
+    /sys/fs/selinux/context to the SANDBOX_WRITE parameter.
+    This is currently needed to work around bug 410687.
+  
      • 
 
    
 
    Installing a SELinux Kernel
    
 
    
@@ -560,7 +568,8 @@ access to the /dev/urandom device:

    Define the Administrator Accounts

    -Finally, we need to map the account(s) you use to manage your system (those +If the SELINUXTYPE is set to strict, then we +need to map the account(s) you use to manage your system (those that need access to Portage) to the staff_u SELinux user. If not, none of your accounts will be able to succesfully manage the system (except for root, but then you will need to login as root directly and not @@ -596,11 +605,16 @@ staff_u:sysadm_r:sysadm_t

    +If you however use a targeted policy, then the user you work with will be +of type unconfined_t and will already have the necessary privileges to +perform system administrative tasks. +

    +

    With that done, enjoy - your first steps into the SELinux world are now made.

    - +

    Page updated January 29, 2012

    Page updated April 10, 2012

    Donate to support our development efforts.

    diff --git a/html/selinux/hb-using-troubleshoot.html b/html/selinux/hb-using-troubleshoot.html index 983cc5a..c18afc1 100644 --- a/html/selinux/hb-using-troubleshoot.html +++ b/html/selinux/hb-using-troubleshoot.html @@ -95,6 +95,31 @@ selinux USE flag is in place, and reinstall sys-app the selinux USE flag is not in place, check your Gentoo profile and make sure it points to a selinux/v2refpolicy/... profile.

    +

    Policy Store is Corrupt

    +

    +If you encounter problems during boot-up or semodule operations which +fail with loading problems, but cannot be resolved with the above solution, then +you might need to reinstall the policies after eliminating the corrupt store. +

    + + + +

    Code Listing1.1: Recovering from store corruption

    +~# semodule -n -B
+libsemanage.semanage_load_module: Error while reading from module file
+/etc/selinux/targeted/modules/tmp/base.pp. (No such file or directory)
+
+~# setenforce 0
+~# mv /etc/selinux/targeted /etc/selinux/targeted.old
+~# FEATURES="-selinux" emerge -1av $(qlist -IC sec-policy)
+~# restorecon -R /etc/selinux
+
    +

    +This will effectively disable the current, corrupted SELinux policy store and +then use Portage to reinstall all SELinux policy packages that are installed on +the system. When done, the file contexts of /etc/selinux are +restored, after which you should be able to continue. +

    1. Unable to Log On

    Problem Description

    @@ -267,7 +292,7 @@ disable its SELinux support. To relabel the entire file system, use     		- +

    Page updated December 11, 2011

    Page updated April 10, 2012

    Donate to support our development efforts.

    -- cgit v1.2.3-65-gdbad