LinuxCon+ContainerCon Europe 2016

Seccomp (secure computing) is a means to limit the system calls a program may make: it can be used to select exactly which system calls are permitted (or denied) and to restrict the arguments that may be passed to those system calls. System call filtering is achieved by writing BPF programs--programs written for a small in-kernel virtual machine that is able to examine system call numbers and arguments. Among other uses, seccomp is by now a key component of various container systems such as Docker and LXC. In this session, I'll provide a bottom-up view of seccomp before going on to examine the BPF virtual machine and some practical examples of filtering programs that restrict the set of permitted system calls. The goal is to give developers and administrators using container frameworks a solid understanding of a tool that has become a fundamental component of container frameworks.