From Fedora Project Wiki
(Moved to FeatureReadyForFesco, ticket #904)
 
(5 intermediate revisions by 3 users not shown)
Line 16: Line 16:
== Current status ==
== Current status ==
* Targeted release: [[Releases/18 | Fedora 18 ]]  
* Targeted release: [[Releases/18 | Fedora 18 ]]  
* Last updated: June 27, 2012
* Last updated: August 16, 2012
* Percentage of completion: 60%
* Percentage of completion: 100%


== Detailed Description ==
== Detailed Description ==
Line 31: Line 31:
* Get seccomp into upstream kernel: DONE, present in 3.5-rc1
* Get seccomp into upstream kernel: DONE, present in 3.5-rc1
* Package libseccomp for Fedora: DONE, present in Fedora Rawhide [https://bugzilla.redhat.com/show_bug.cgi?id=830992 BZ 830992]
* Package libseccomp for Fedora: DONE, present in Fedora Rawhide [https://bugzilla.redhat.com/show_bug.cgi?id=830992 BZ 830992]
* Get the QEMU/libseccomp patch accepted upstream: IN PROGRESS (v2 patch posted on June 13th by IBM)
* Get the QEMU/libseccomp patch accepted upstream: DONE, present in 1.2-rc0
* Update Fedora QEMU package to build against libseccomp: NOT DONE
* Update Fedora QEMU package to build against libseccomp: NOT DONE


Line 49: Line 49:
-->
-->
Kernel
Kernel
* The traditional kernel regression tests should be preformed to ensure that the kernel's seccomp functionality does not impact the expected functionality when not enabled by the application at runtime.
* The traditional kernel regression tests should be preformed to ensure that the kernel's seccomp functionality does not impact the expected functionality when not enabled by the application at runtime.  Requires Linux >= 3.5 built with CONFIG_SECCOMP_FILTER enabled.


Libseccomp
Libseccomp
Line 56: Line 56:


QEMU
QEMU
* The traditional QEMU regression tests should be performed to ensure that QEMU's normal functionality is not impacted by the libseccomp patches.
* The traditional QEMU regression tests should be performed to ensure that QEMU's normal functionality is not impacted by the libseccomp patches.  Requires libseccomp >= 1.0.0 and QEMU 1.2.  QEMU should be built with the "--enable-libseccomp" flag and run with the "-sandbox on" command line option.


== User Experience ==
== User Experience ==
Line 85: Line 85:




[[Category:FeatureReadyForFesco]]
[[Category:FeatureAcceptedF18]]
<!-- When your feature page is completed and ready for review -->
<!-- When your feature page is completed and ready for review -->
<!-- remove Category:FeaturePageIncomplete and change it to Category:FeatureReadyForWrangler -->
<!-- remove Category:FeaturePageIncomplete and change it to Category:FeatureReadyForWrangler -->
<!-- After review, the feature wrangler will move your page to Category:FeatureReadyForFesco... if it still needs more work it will move back to Category:FeaturePageIncomplete-->
<!-- After review, the feature wrangler will move your page to Category:FeatureReadyForFesco... if it still needs more work it will move back to Category:FeaturePageIncomplete-->
<!-- A pretty picture of the page category usage is at: https://fedoraproject.org/wiki/Features/Policy/Process -->
<!-- A pretty picture of the page category usage is at: https://fedoraproject.org/wiki/Features/Policy/Process -->

Latest revision as of 21:33, 16 August 2012


Syscall Filters

Summary

Syscall filtering is a security mechanism that allows applications to define which syscalls they should be allowed to execute.

Owner

  • Name: Cole Robinson
  • Email: crobinso@redhat.com
  • Name: Paul Moore
  • Email: pmoore@redhat.com

Current status

  • Targeted release: Fedora 18
  • Last updated: August 16, 2012
  • Percentage of completion: 100%

Detailed Description

The syscall filtering concept, and the motivation behind it, is fairly simple; the Linux Kernel supports a very large number of system calls (syscalls), over 300 on x86_64 for the 64 bit implementations alone, with applications typically requiring only a very small subset of these syscalls to function normally. Through the use of syscall filters we can disable certain syscalls on an application by application basis, limiting the potential attack surface of the kernel and reducing the likelihood that a malicious application could exploit a kernel vulnerability.

The Linux Kernel's enhanced/mode-2 seccomp functionality is designed to allow applications to specify a filter that is applied to their own syscalls; the filter can specify just the syscall itself or the syscall in conjunction with a specific set of arguments. The kernel's seccomp filter API is the Berkley Packet Filter (BPF) language, the same as used in the Linux socket filters, but adapted for use with syscalls. The libseccomp library adds an abstraction layer on top of the kernel's seccomp API, allowing application developers a more user-friendly API based on function calls and not the BPF assembly language.

Benefit to Fedora

Increased resistance to exploiting kernel vulnerabilities from applications which implement seccomp based syscall filtering.

Scope

  • Get seccomp into upstream kernel: DONE, present in 3.5-rc1
  • Package libseccomp for Fedora: DONE, present in Fedora Rawhide BZ 830992
  • Get the QEMU/libseccomp patch accepted upstream: DONE, present in 1.2-rc0
  • Update Fedora QEMU package to build against libseccomp: NOT DONE

How To Test

Kernel

  • The traditional kernel regression tests should be preformed to ensure that the kernel's seccomp functionality does not impact the expected functionality when not enabled by the application at runtime. Requires Linux >= 3.5 built with CONFIG_SECCOMP_FILTER enabled.

Libseccomp

  • The libseccomp sources contain a series of automated tests which can be used to test the library's internal seccomp filter generation. It is important to note that these automated tests are tested via a seccomp BPF simulator and not the kernel.
  • A simple negative test could be developed to validate that libseccomp and the kernel perform as expected when a syscall is blocked.

QEMU

  • The traditional QEMU regression tests should be performed to ensure that QEMU's normal functionality is not impacted by the libseccomp patches. Requires libseccomp >= 1.0.0 and QEMU 1.2. QEMU should be built with the "--enable-libseccomp" flag and run with the "-sandbox on" command line option.

User Experience

Ideally this feature shouldn't be noticeable to the user, the syscall filtering should allow normal execution of the application. Intention is that only people trying to exploit security holes notice that the syscall they are trying to use is blocked :)

Dependencies

  • Kernel updated to 3.5
  • libseccomp included in Fedora
  • QEMU upstream includes support for libseccomp

Applications other than QEMU wishing to use libseccomp only require the kernel and libseccomp support items listed above.

Contingency Plan

Since this is brand new functionality, if it doesn't make it in time for F18, nothing has changed. We just drop this feature page.

Documentation

Release Notes

  • The libseccomp library is now available, which provides applications with an easy way to reduce the potential damage of exploits, leveraging kernel syscall filters. Virtual machines benefit from this as QEMU/KVM now uses libseccomp.

Comments and Discussion