Annotation of wikisrc/rumpkernel.mdwn, revision 1.5
1.1 pooka 1: **Contents**
3: [[!toc levels=2]]
1.5 ! pooka 5: This page is about rump kernels in NetBSD and assumes the reader knows
! 6: the basics of rump kernels. See http://www.rumpkernel.org/ for general
! 7: information about rump kernels.
! 9: ## System security
! 11: File system drivers are vulnerable to consistency errors in
! 12: file system images, see e.g.
! 13: [here](http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.114.4312)
! 15: What this vulnerability means is that whenever an untrusted file system
! 16: image is mounted using an in-kernel driver, system compromise should be
! 17: expected. This untrusted images include for example ones on USB sticks.
! 18: There are heavyweight workarounds for the problem, for example including
! 19: virtual machines.
! 21: NetBSD allows transparently mounting an untrusted file system image by
! 22: running the kernel driver in a rump kernel in userspace. The driver
! 23: is thus isolated and any damage that a malicious file system image
! 24: can directly cause is restricted to a userspace process. From a user
! 25: perspective, mounting with the `-o rump` option is the only change
! 26: required, or `rump` in `/etc/fstab`. Notably, even though interacting
! 27: with untrusted file systems will suffer from a minor performance penalty,
! 28: the performance of mounts from trusted file systems is completely
! 29: unaffected.
! 32: ## Automated testing
! 34: The problems of automated kernel testing are documented for example in
! 35: [The Design and Implementation of the Anykernel and Rump Kernels](http://lib.tkk.fi/Diss/2012/isbn9789526049175/isbn9789526049175.pdf).
! 36: Rump kernels are used in the continuous tests run by the NetBSD project.
! 37: See http://releng.NetBSD.org/ for the results or the NetBSD source tree
! 38: under `src/tests` for the test programs themselves.
! 41: ## Kernel development
! 43: On the flipside of testing is kernel development. Rump kernels allow
! 44: developing kernel drivers in a test-driven manner, including both unit
! 45: tests and integration tests. Since the iteration time with a rump
! 46: kernel is in the subsecond range, the development process is smoother
! 47: than with a virtual machine. Also, the tests written during development
! 48: can be entered into the automated tests (see above), and later used
! 49: for further development. This method avoids "throw-away" tests that
! 50: are hardcoded for one virtual machine environment and unusable in both
! 51: automated testing and further development done in another environment.
1.1 pooka 52:
54: ## Source Code
56: You can also [browse](http://cvsweb.NetBSD.org/bsdweb.cgi/src/) the
57: source code history online. Code is found from all areas of the source
58: tree. Some examples of where to look include
60: [src/usr.bin](http://cvsweb.NetBSD.org/bsdweb.cgi/src/usr.bin/) and
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