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[Linux Kernel Exploitation 0x0] Debugging the Kernel with QEMU

Hi folks, in this post I'm going to walk through how to setup the linux kernel for debugging. I will also demonstrate that the setup works by setting a break-point to a test driver I wrote myself. All the code will be available from my gitlab, all the links to my gitlab will be re-posted at the end. The setup I describe here re-uses some parts of the syzkaller setup, and for good reason later on in the post series I will break into a tutorial for the syzkaller tool as well. So lets get on with it. Screenshot of a successful debug session with full debug symbols for the kernel! We can even see the call to start_kernel and a frame before that as well! The Process Okay so we want to study kernel exploitation but given that the kernel isn't something totally accessible in userspace, its not as convenient to debug as userpace stuff, we need a bit of a run up before we can actually poke and prod the kernel to figure out how to write our exploits. So there's a number of importa

Introduction to the ELF Format (Part VI) : The Symbol Table and Relocations (Part 1)

This post is part of a series on the ELF format, if you haven't checked out the other parts of the series here they are: (Part I) : ELF Header https://blog.k3170makan.com/2018/09/introduction-to-elf-format-elf-header.html (Part II) : Program Headers https://blog.k3170makan.com/2018/09/introduction-to-elf-format-part-ii.html (Part III) : Section Header Table https://blog.k3170makan.com/2018/09/introduction-to-elf-file-format-part.html (Part IV) : Section Types and Special Sections https://blog.k3170makan.com/2018/10/introduction-to-elf-format-part-iv.html (Part V) : C Start up https://blog.k3170makan.com/2018/10/introduction-to-elf-format-part-v.html this In this and the next post I'm going to explore how Elf files manage to pull off the magic of symbol resolution as well as the format, offsets and records in the Elf that represent this information. There are many facets to this mechanism in the format, and before I get into each of them I'd like to

Introduction to the ELF Format : The ELF Header (Part I)

ELF Files are charged with using their magic to perform two holy tasks in the linux universe. The first being to tell the kernel where to place stuff in memory from the ELF file on disk as well as providing ways to invoke the dynamic loaders functions and maybe even help out with some debugging information. Essentially speaking its telling the kernel where to put it in memory and also the plethora of tools that interpret the file where all the data structures are that hold useful information for making sense of the file. Anyway that's as far as I've figured it out - the actual break down is a little less simple. I'll demonstrate why this is so here and over the next series of posts in the classic "Learn things by breaking them" style. ELF Header and Identification fields The first thing that appears in an ELF file is of course the header, which is like most things in file formats just a list of offsets in the file. Its purpose is to indicate essentially wha

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Keith Makan