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Annotation of wikisrc/rumpkernel.mdwn, revision 1.5

1.1       pooka       1: **Contents**
                      2: 
                      3: [[!toc levels=2]]
                      4: 
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.
        !             8: 
        !             9: ## System security
        !            10: 
        !            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)
        !            14: 
        !            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.
        !            20: 
        !            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.
        !            30: 
        !            31: 
        !            32: ## Automated testing
        !            33: 
        !            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.
        !            39: 
        !            40: 
        !            41: ## Kernel development
        !            42: 
        !            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: 
                     53: 
                     54: ## Source Code
                     55: 
                     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
                     59: [src/lib](http://cvsweb.NetBSD.org/bsdweb.cgi/src/lib/),
                     60: [src/usr.bin](http://cvsweb.NetBSD.org/bsdweb.cgi/src/usr.bin/) and
                     61: [src/sys/rump](http://cvsweb.NetBSD.org/bsdweb.cgi/src/sys/rump/).