From d0559e92af5a7d7a4441b6a8cab39accab6e29bc Mon Sep 17 00:00:00 2001
From: Dan Walsh <dwalsh@redhat.com>
Date: Mon, 21 Apr 2014 17:09:26 -0400
Subject: [PATCH] This patch reworks the SELinux patch to be only run on demand
 by the daemon

Added --selinux-enable switch to daemon to enable SELinux labeling.

The daemon will now generate a new unique random SELinux label when a
container starts, and remove it when the container is removed.   The MCS
labels will be stored in the daemon memory.  The labels of containers will
be stored in the container.json file.

When the daemon restarts on boot or if done by an admin, it will read all containers json files and reserve the MCS labels.

A potential problem would be conflicts if you setup thousands of containers,
current scheme would handle ~500,000 containers.

Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: rhatdan)
Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: crosbymichael)
---
 label/label.go          |  4 ++++
 label/label_selinux.go  |  4 ++++
 selinux/selinux.go      | 28 ++++++++++++++++++++++++----
 selinux/selinux_test.go |  2 ++
 4 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/label/label.go b/label/label.go
index 38f026b..434e1c5 100644
--- a/label/label.go
+++ b/label/label.go
@@ -24,3 +24,7 @@ func GetPidCon(pid int) (string, error) {
 
 func Init() {
 }
+
+func ReserveLabel(label string) error {
+	return nil
+}
diff --git a/label/label_selinux.go b/label/label_selinux.go
index 2f67ee4..9361a71 100644
--- a/label/label_selinux.go
+++ b/label/label_selinux.go
@@ -75,3 +75,7 @@ func GetPidCon(pid int) (string, error) {
 func Init() {
 	selinux.SelinuxEnabled()
 }
+
+func ReserveLabel(label string) {
+	selinux.ReserveLabel(label)
+}
diff --git a/selinux/selinux.go b/selinux/selinux.go
index edabc4f..422c39b 100644
--- a/selinux/selinux.go
+++ b/selinux/selinux.go
@@ -204,6 +204,13 @@ func NewContext(scon string) SELinuxContext {
 	return c
 }
 
+func ReserveLabel(scon string) {
+	if len(scon) != 0 {
+		con := strings.SplitN(scon, ":", 4)
+		mcsAdd(con[3])
+	}
+}
+
 func SelinuxGetEnforce() int {
 	var enforce int
 
@@ -229,8 +236,12 @@ func SelinuxGetEnforceMode() int {
 	return Disabled
 }
 
-func mcsAdd(mcs string) {
+func mcsAdd(mcs string) error {
+	if mcsList[mcs] {
+		return fmt.Errorf("MCS Label already exists")
+	}
 	mcsList[mcs] = true
+	return nil
 }
 
 func mcsDelete(mcs string) {
@@ -283,15 +294,21 @@ func uniqMcs(catRange uint32) string {
 			}
 		}
 		mcs = fmt.Sprintf("s0:c%d,c%d", c1, c2)
-		if mcsExists(mcs) {
+		if err := mcsAdd(mcs); err != nil {
 			continue
 		}
-		mcsAdd(mcs)
 		break
 	}
 	return mcs
 }
 
+func FreeLxcContexts(scon string) {
+	if len(scon) != 0 {
+		con := strings.SplitN(scon, ":", 4)
+		mcsDelete(con[3])
+	}
+}
+
 func GetLxcContexts() (processLabel string, fileLabel string) {
 	var (
 		val, key string
@@ -344,7 +361,8 @@ func GetLxcContexts() (processLabel string, fileLabel string) {
 	}
 
 exit:
-	mcs := IntToMcs(os.Getpid(), 1024)
+	//	mcs := IntToMcs(os.Getpid(), 1024)
+	mcs := uniqMcs(1024)
 	scon := NewContext(processLabel)
 	scon["level"] = mcs
 	processLabel = scon.Get()
@@ -373,6 +391,8 @@ func CopyLevel(src, dest string) (string, error) {
 	}
 	scon := NewContext(src)
 	tcon := NewContext(dest)
+	mcsDelete(tcon["level"])
+	mcsAdd(scon["level"])
 	tcon["level"] = scon["level"]
 	return tcon.Get(), nil
 }
diff --git a/selinux/selinux_test.go b/selinux/selinux_test.go
index fde6ab1..9a3a552 100644
--- a/selinux/selinux_test.go
+++ b/selinux/selinux_test.go
@@ -31,9 +31,11 @@ func TestSELinux(t *testing.T) {
 		plabel, flabel = selinux.GetLxcContexts()
 		t.Log(plabel)
 		t.Log(flabel)
+		selinux.FreeLxcContexts(plabel)
 		plabel, flabel = selinux.GetLxcContexts()
 		t.Log(plabel)
 		t.Log(flabel)
+		selinux.FreeLxcContexts(plabel)
 		t.Log("getenforce ", selinux.SelinuxGetEnforce())
 		t.Log("getenforcemode ", selinux.SelinuxGetEnforceMode())
 		pid := os.Getpid()