From 54a20025b15795bf3d6bd2435b8e83dbbca55a64 Mon Sep 17 00:00:00 2001 From: Fabricio Voznika Date: Sat, 28 Apr 2018 11:12:01 -0700 Subject: Fix center alignment github markdown doesn't like {style} tags. Also moved the image after their respective section. PiperOrigin-RevId: 194663070 Change-Id: I7a7b97c1bc6f2b368837a3aa936f8bd3c00469fd --- README.md | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) (limited to 'README.md') diff --git a/README.md b/README.md index 3b8ad1857..e5fc31ac8 100644 --- a/README.md +++ b/README.md @@ -35,9 +35,6 @@ made available to a container. Two other approaches are commonly taken to provide stronger isolation than native containers. -![Machine-level virtualization](g3doc/Machine-Virtualization.png "Machine-level -virtualization"){style="display:block;margin:auto"} - **Machine-level virtualization**, such as [KVM][kvm] and [Xen][xen], exposes virtualized hardware to a guest kernel via a Virtual Machine Monitor (VMM). This virtualized hardware is generally enlightened (paravirtualized) and additional @@ -48,7 +45,7 @@ performance (though nested virtualization may bring challenges in this area), but for containers it often requires additional proxies and agents, and may require a larger resource footprint and slower start-up times. -![Rule-based execution](g3doc/Rule-Based-Execution.png "Rule-based execution"){style="display:block;margin:auto"} +

**Rule-based execution**, such as [seccomp][seccomp], [SELinux][selinux] and [AppArmor][apparmor], allows the specification of a fine-grained security policy @@ -63,7 +60,7 @@ making this approach challenging to apply universally. Rule-based execution is often combined with additional layers for defense-in-depth. -![gVisor](g3doc/Layers.png "gVisor"){style="display:block;margin:auto"} +

**gVisor** provides a third isolation mechanism, distinct from those mentioned above. @@ -79,6 +76,8 @@ reduced application compatibility and higher per-system call overhead. On top of this, gVisor employs rule-based execution to provide defense-in-depth (details below). +

+ gVisor's approach is similar to [User Mode Linux (UML)][uml], although UML virtualizes hardware internally and thus provides a fixed resource footprint. @@ -107,8 +106,6 @@ application to directly control the system calls it makes. ### File System Access -![Sentry](g3doc/Sentry-Gofer.png){style="display:block;margin:auto"} - In order to provide defense-in-depth and limit the host system surface, the gVisor container runtime is normally split into two separate processes. First, the *Sentry* process includes the kernel and is responsible for executing user @@ -122,6 +119,8 @@ access itself. Furthermore, the Sentry runs in an empty user namespace, and the system calls made by gVisor to the host are restricted using seccomp filters in order to provide defense-in-depth. +

+ ### Network Access The Sentry implements its own network stack (also written in Go) called -- cgit v1.2.3