An upper layer protocol for Lua scripting.
ULP Lua is a kernel module that provides scripting capabilites for the in-kernel socket structure. It achieves this by using a modified version of the Lua 5.3 virtual machine that runs in kernel mode.
ULP Lua is dependant on a new feature introduced in the Linux kernel called upper layer protocol (ULP). This new feature allow the user to attach L4 capabilites and extend the in-kernel socket. It's the bones used on mainline in TLS in Kernel.
ULP was merged in the 4.1x series, but the patch is trivial and can be backported.
ULP Lua can be used in a number of different applications, such as zero copy L4 in-kernel introspection, WAFs, proxies, etc...
ULP Lua has a design goal to work directly on skbs and leverage zero copy whenever it's possible.
Current known limitations are listed below and are intented to be fixed in the future.
--> No support for fragmented skbs.
--> No support for sparse buffer pattern matching.
--> No Lua API for common socket operations.
--> No support for udp.
ULP Lua is licensed as GPL v2.
You can contribute to this project via pull requests and issues.
The directory structure is:
dependencies -- where all the dependencies are, usually in submodules.
src -- where the kernel module sources are.
tests -- where all the tests programs and resource validators are.
docs -- where all the in-depth documentations are.
The code contains helpful comments as well, at least for me :).
ULP Lua is a project born out of my bachelor's thesis at PUC-Rio.
Since Linux 4.20 the ULP infrastructure has changed. Now we require a kernel >= 4.20.
If you wish to use an older version, please backport module.c.