Again, you will have full access and control of your You will develop your security module for the linux-4.4 kernel that youĬompiled as part of MP0. In this assignment, you will again work on the provided Virtual Machine and Default modules can be configured atīuild-time using CONFIG_DEFAULT_SECURITY but can also be overridden atīoot-time using the security= (or, for more recent kernel versions Security modules must be compiled alongside the kernel and enabled through theĪppropriate configuration switches. Not loadable at runtime (the term “module” in LSM is somewhat of a misnomer). That security modules, unlike the modules we have previously developed, are Figure 1: LSM Hook Architecture Example įigure 1 shows the LSM hook architecture for a sample open system call. Their description is located in include/linux/lsm_hooks.h. The full list of the hooks exposed to security modules, along with Order: after performing error checking, the kernel consults the discretionaryĪccess control mechanism, then calls the hooks for the minor modules if anyĪre present, followed by the hooks of the major security module in place at Generally, the access control checks occur in the following The LSM framework works by introducing hooks into a wide variety of kernelįunctionalities. In this machine problem, we will be developing a major security module. That these changes are very recent, and don’t apply for Linux v4.4). Not, but this distinction is fading with more recent kernel releases. Opaque security blobs provided by the LSM framework while minor modules did Historically, major modules had access to Module running in a given system, while minor modules can be stacked to In order to allow for module stacking, the security modules are separated into ![]() Safesetid, SELinux, Smack, TOMOYO Linux, and Yama. The currently accepted security modules in the mainstream kernel areĪppArmor, bpf (for eBPF hooks), integrity, LoadPin, Lockdown, The LSM framework has allowed developers to add supportįor various security models without the need for changes to the core kernelĬode. By default, the Linux kernel provides support for discretionaryĪccess control, and prior to LSM, lacked support for more general accessĬontrol mechanisms. The goal of the LSM project is to provide aįramework for general access-control without the need to modify the main The NSA when they presented their work on Security Enhanced Linux (SELinux) at The Linux Security Module (LSM) project grew out of a discussion initiated by EC Checkpoint 2: Complete all steps in Part 1, Part 2, and Part 3 by Monday, Apr.EC Checkpoint 1: Complete all steps in Part 1 by Monday, Apr.You can earn extra credit by starting on this MP early: Enforce the implemented policy using the implemented LSM.Design a Least Privilege Policy for /usr/bin/passwd.Design and implement a simple Linux Security Module.Add custom kernel configuration parameters and enable them upon compilation.Understand the basic concepts behind extended file system attributes. ![]()
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