38 lines
1.5 KiB
Markdown
38 lines
1.5 KiB
Markdown
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# mkkmod
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Pack a binary into a self-contained, self-executing Linux kernel module using the usermode driver infrastructure.
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Adapted from [an example by Richard Weinberger](https://sigma-star.at/blog/2023/07/embedded-go-prog/).
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License: GPL-2.0-only
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## Usage
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- Build sample binary to embed: `./build-sample.sh`
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- Build kernel module: `./build-module.sh ./sample`
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- To build for the non-running kernel: `KERN_VER=6.9.8-200.fc40.x86_64 ./build-module.sh ./sample`
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- Run: `insmod ./eprog.ko`
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## Requirements
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- The generated module must have a GPL-compatible license to use `EXPORT_SYMBOL_GPL` functions.
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- Requires kernel 5.9 or later.
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- Kernel version needs to export the umd functionality.
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If you get errors of the form `modpost: "fork_usermode_driver" [...] undefined!` check if your kernel exposes the functions in `/usr/src/linux-headers-$(uname -r)/Module.symvers` and/or that the functions are present in `/proc/kallsyms`.
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Compatibility tests:
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|Distro|Kernel version|Notes
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|---|---|---
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|Debian 12|6.1.0-22|❌ Missing symbols
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|Fedora 40|6.9.8-200|✅ Features are present
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## Reference
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- https://sigma-star.at/blog/2023/07/embedded-go-prog/
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- https://git.kernel.org/pub/scm/linux/kernel/git/rw/misc.git/tree/drivers/misc/embedded_prog?h=embedded_go_prog
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- https://medium.com/@adityapatnaik27/linux-kernel-module-in-tree-vs-out-of-tree-build-77596fc35891
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- https://github.com/torvalds/linux/blob/master/include/linux/usermode_driver.h
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- https://github.com/torvalds/linux/blob/master/kernel/usermode_driver.c
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