Unattended encrypted kernel crash dumps

Student: KonradWitaszczyk
Mentor: GlebKurtsou

Project description

Kernel dump may contain a backtrace of function calls, information about processes or even device data. These information should not be seen by a person trying to attack our OS because it might help to hack it. The main goal of the project is to implement encrypted crash dumps. It means that a user will have to decrypt a dump before analysing it. Crash dumps will be encrypted with an one-time AES key which will be shared with a user using an asymmetric key encryption.

In order to finish this feature it is required to modify crash dump routines, savecore(8) and crashinfo(8). Our solution will use a random symmetric key to encrypt data with AES using XTS mode which will be encrypted with an asymmetric key chosen by a user. We will start with constant keys to implement encryption and then we will make it more user-friendly. After reboot caused by a panic, savecore(8) will copy the dump and its key to dumpdir and make it able to decrypt with PEFS.

During my work I will be sending reports every Monday to the soc-status@FreeBSD.org mailing list:

Write a rc.d script to generate a symmetric key and encrypt it with an asymmetric key.
Change crash dump routines to write an encrypted data in a dump device.
Change savecore(8) to store the encrypted dump and its encrypted symmetric key in dumpdir.
Change crashinfo(8) to save an encrypted crash summary along with a crash dump.

June 17: Start of coding
June 24: Define a new format of a crash dump header and change savecore(8) to support it
July 1: Import and change PEFS library to encrypt crash dumps
July 8: Encrypt a crash dump with a constant AES key
July 15: Change savecore(8) to save encrypted crash dumps with its key
July 22: Change savecore(8) to support PEFS
July 29-August 2: Mid-term Evaluations
August 5: Generate a random one-time symmetric key
August 12: Encrypt a crash dump with the random symmetric key
August 19: Decrypt a crash dump with the encrypted random symmetric key (savecore(8))
August 26: Decrypt a crash dump with the encrypted random symmetric key (PEFS)
September 2: Encrypt a crash summary
September 9: Tests and documentation
September 16: End of coding (soft)
September 23: End of coding (hard)

I would like to test my project in the following stages:

Encrypting with a constant AES key.
Decrypting with PEFS after savecore(8) changes.
Exchanging an one-time AES key.
Encrypting/decrypting with the one-time AES key.
Encrypting/decrypting crash summaries.

In order to test the project I will use a diskless virtual machine with a memory disk on a host machine as a dump device. Panics will be forced with the special sysctl variable: sysctl debug.kdb.panic=1.

Modified FreeBSD-HEAD: https://svnweb.freebsd.org/socsvn/soc2013/def/crashdump-head/

The project was presented at FreeBSD Developer Summit during EuroBSDcon 2013. You can find the presentation here.

Project in Melange: http://www.google-melange.com/gsoc/project/google/gsoc2013/def/25001

Kernel Debugging: http://www.freebsd.org/doc/en/books/developers-handbook/kerneldebug.html

The XTS-AES Mode for Confidentiality on Storage Devices: http://csrc.nist.gov/publications/nistpubs/800-38E/nist-sp-800-38E.pdf

Efficient Instantiations of Tweakable Blockciphers and Refinements to Modes OCB and PMAC: http://www.cs.ucdavis.edu/~rogaway/papers/offsets.pdf

PEFS: PEFS

savecore(8): http://www.freebsd.org/cgi/man.cgi?query=savecore&sektion=8

NFS Mount Network Booting VirtualBox: http://blog.eitanadler.com/2012/10/nfs-mount-network-booting-virtualbox.html

FreeBSD Development for Smarties. The quest for a better kernel development environment: https://www.bsdcan.org/2010/schedule/attachments/144_bsdcan2010_lstewart_smarties.pdf