From f6fadd2ffe454ad9ef62511d65448f0b584907f0 Mon Sep 17 00:00:00 2001
From: Vivek Goyal <vgoyal@redhat.com>
Date: Thu, 1 Oct 2015 17:03:02 -0400
Subject: [PATCH] Start parsing rootfsPropagation and make it effective

spec introduced a new field rootfsPropagation. Right now that field
is not parsed by runc and it does not take effect. Starting parsing
it and for now allow only limited propagation flags. More can be
opened as new use cases show up.

We are apply propagation flags on / and not rootfs. So ideally
we should introduce another field in spec say rootPropagation. For
now I am parsing rootfsPropagation. Once we agree on design, we
can discuss if we need another field in spec or not.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
 spec.go | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/spec.go b/spec.go
index 90876d7ce..6d5a6ca63 100644
--- a/spec.go
+++ b/spec.go
@@ -280,6 +280,16 @@ var namespaceMapping = map[specs.NamespaceType]configs.NamespaceType{
 	specs.UTSNamespace:     configs.NEWUTS,
 }
 
+var mountPropagationMapping = map[string]int{
+	"rprivate": syscall.MS_PRIVATE | syscall.MS_REC,
+	"private":  syscall.MS_PRIVATE,
+	"rslave":   syscall.MS_SLAVE | syscall.MS_REC,
+	"slave":    syscall.MS_SLAVE,
+	"rshared":  syscall.MS_SHARED | syscall.MS_REC,
+	"shared":   syscall.MS_SHARED,
+	"":         syscall.MS_PRIVATE | syscall.MS_REC,
+}
+
 // loadSpec loads the specification from the provided path.
 // If the path is empty then the default path will be "config.json"
 func loadSpec(cPath, rPath string) (spec *specs.LinuxSpec, rspec *specs.LinuxRuntimeSpec, err error) {
@@ -329,12 +339,17 @@ func createLibcontainerConfig(cgroupName string, spec *specs.LinuxSpec, rspec *s
 		rootfsPath = filepath.Join(cwd, rootfsPath)
 	}
 	config := &configs.Config{
-		Rootfs:          rootfsPath,
-		Capabilities:    spec.Linux.Capabilities,
-		Readonlyfs:      spec.Root.Readonly,
-		Hostname:        spec.Hostname,
-		RootPropagation: syscall.MS_PRIVATE | syscall.MS_REC,
+		Rootfs:       rootfsPath,
+		Capabilities: spec.Linux.Capabilities,
+		Readonlyfs:   spec.Root.Readonly,
+		Hostname:     spec.Hostname,
 	}
+
+	exists := false
+	if config.RootPropagation, exists = mountPropagationMapping[rspec.Linux.RootfsPropagation]; !exists {
+		return nil, fmt.Errorf("rootfsPropagation=%v is not supported", rspec.Linux.RootfsPropagation)
+	}
+
 	for _, ns := range rspec.Linux.Namespaces {
 		t, exists := namespaceMapping[ns.Type]
 		if !exists {