deploy/core: kubearmor for GKE latest COS images

* latest GKE COS images do not have path for /usr/src.
* deploygen updated to create kubearmor.yamls accordingly

Detailed description:
GKE supports multiple images types, viz COS and non-COS(Ubuntu, Debian
etc). In case of non-COS images, the `/usr/src` contains the kernel
headers. In case of COS, kubearmor internally downloads the kernel
headers but still it used to mount `/usr/src` since we used a single yaml
for COS and non-COS images. In the latest releases of COS images
(for e.g., 1.22.6-gke-1000), the `/usr/src` folder is no longer
present. The current changes now mounts /usr to /opt/hostusr folder for
GKE (only). The kubearmor code internally sets `BCC_KERNEL_SOURCE` to
`/opt/hostusr/src/linux-headers-KERNELVER`.

Fixes #579

Signed-off-by: Rahul Jadhav <nyrahul@gmail.com>

KubeArmor/monitor/systemMonitor.go

@@ -158,9 +158,6 @@ type SystemMonitor struct {
 
 	// ticker to clean up exited pids
 	Ticker *time.Ticker
-
-	// GKE
-	IsCOS bool
 }
 
 // NewSystemMonitor Function
@@ -193,8 +190,6 @@ func NewSystemMonitor(node tp.Node, logger *fd.Feeder, containers *map[string]tp
 
 	mon.Ticker = time.NewTicker(time.Second * 10)
 
-	mon.IsCOS = false
-
 	return mon
 }
 
@@ -226,8 +221,20 @@ func (mon *SystemMonitor) InitBPF() error {
 
 				// just for safety
 				time.Sleep(time.Second * 1)
-
-				mon.IsCOS = true
+			} else {
+				// In case of GKE COS release >= 1.22, the base OS img does not
+				// contain /usr/src folder. Thus we now mount /usr folder to
+				// /opt/hostusr folder in kubearmor for GKE. The following code
+				// checks whether the /opt/hostusr/src/kernel-hdrs path exists
+				// and uses it for BCC kernel source, if present.
+				lklhdrpath := "/media/root/usr/src/linux-headers-" + mon.KernelVersion
+				mon.Logger.Printf("checking if kernel headers path (%s) exists", lklhdrpath)
+				if _, err := os.Stat(lklhdrpath); err == nil {
+					mon.Logger.Printf("using kernel headers from (%s)", lklhdrpath)
+					if err := os.Setenv("BCC_KERNEL_SOURCE", lklhdrpath); err != nil {
+						mon.Logger.Errf("setenv failed for [BCC_KERNEL_SOURCE=%s] Error=%s", lklhdrpath, err.Error())
+					}
+				}
 			}
 		}
 	}

deployments/EKS/kubearmor.yaml

@@ -101,9 +101,6 @@ spec:
         terminationMessagePath: /dev/termination-log
         terminationMessagePolicy: File
         volumeMounts:
-        - mountPath: /usr/src
-          name: usr-src-path
-          readOnly: true
         - mountPath: /lib/modules
           name: lib-modules-path
           readOnly: true
@@ -116,6 +113,9 @@ spec:
         - mountPath: /media/root/etc/os-release
           name: os-release-path
           readOnly: true
+        - mountPath: /usr/src
+          name: usr-src-path
+          readOnly: true
         - mountPath: /etc/apparmor.d
           name: etc-apparmor-d-path
         - mountPath: /var/run/containerd/containerd.sock
@@ -138,10 +138,6 @@ spec:
       tolerations:
       - operator: Exists
       volumes:
-      - hostPath:
-          path: /usr/src
-          type: Directory
-        name: usr-src-path
       - hostPath:
           path: /lib/modules
           type: Directory
@@ -162,6 +158,10 @@ spec:
           path: /etc/os-release
           type: File
         name: os-release-path
+      - hostPath:
+          path: /usr/src
+          type: Directory
+        name: usr-src-path
       - hostPath:
           path: /etc/apparmor.d
           type: DirectoryOrCreate

deployments/GKE/kubearmor.yaml

@@ -101,9 +101,6 @@ spec:
         terminationMessagePath: /dev/termination-log
         terminationMessagePolicy: File
         volumeMounts:
-        - mountPath: /usr/src
-          name: usr-src-path
-          readOnly: true
         - mountPath: /lib/modules
           name: lib-modules-path
           readOnly: true
@@ -116,6 +113,9 @@ spec:
         - mountPath: /media/root/etc/os-release
           name: os-release-path
           readOnly: true
+        - mountPath: /media/root/usr
+          name: usr-src-path
+          readOnly: true
         - mountPath: /etc/apparmor.d
           name: etc-apparmor-d-path
         - mountPath: /var/run/containerd/containerd.sock
@@ -138,10 +138,6 @@ spec:
       tolerations:
       - operator: Exists
       volumes:
-      - hostPath:
-          path: /usr/src
-          type: Directory
-        name: usr-src-path
       - hostPath:
           path: /lib/modules
           type: Directory
@@ -162,6 +158,10 @@ spec:
           path: /etc/os-release
           type: File
         name: os-release-path
+      - hostPath:
+          path: /usr
+          type: Directory
+        name: usr-src-path
       - hostPath:
           path: /etc/apparmor.d
           type: DirectoryOrCreate

deployments/docker/kubearmor.yaml

@@ -101,9 +101,6 @@ spec:
         terminationMessagePath: /dev/termination-log
         terminationMessagePolicy: File
         volumeMounts:
-        - mountPath: /usr/src
-          name: usr-src-path
-          readOnly: true
         - mountPath: /lib/modules
           name: lib-modules-path
           readOnly: true
@@ -116,6 +113,9 @@ spec:
         - mountPath: /media/root/etc/os-release
           name: os-release-path
           readOnly: true
+        - mountPath: /usr/src
+          name: usr-src-path
+          readOnly: true
         - mountPath: /etc/apparmor.d
           name: etc-apparmor-d-path
         - mountPath: /var/run/docker.sock
@@ -135,10 +135,6 @@ spec:
       tolerations:
       - operator: Exists
       volumes:
-      - hostPath:
-          path: /usr/src
-          type: Directory
-        name: usr-src-path
       - hostPath:
           path: /lib/modules
           type: Directory
@@ -159,6 +155,10 @@ spec:
           path: /etc/os-release
           type: File
         name: os-release-path
+      - hostPath:
+          path: /usr/src
+          type: Directory
+        name: usr-src-path
       - hostPath:
           path: /etc/apparmor.d
           type: DirectoryOrCreate

deployments/generic/kubearmor.yaml

@@ -101,9 +101,6 @@ spec:
         terminationMessagePath: /dev/termination-log
         terminationMessagePolicy: File
         volumeMounts:
-        - mountPath: /usr/src
-          name: usr-src-path
-          readOnly: true
         - mountPath: /lib/modules
           name: lib-modules-path
           readOnly: true
@@ -116,6 +113,9 @@ spec:
         - mountPath: /media/root/etc/os-release
           name: os-release-path
           readOnly: true
+        - mountPath: /usr/src
+          name: usr-src-path
+          readOnly: true
         - mountPath: /etc/apparmor.d
           name: etc-apparmor-d-path
         - mountPath: /var/run/containerd/containerd.sock
@@ -138,10 +138,6 @@ spec:
       tolerations:
       - operator: Exists
       volumes:
-      - hostPath:
-          path: /usr/src
-          type: Directory
-        name: usr-src-path
       - hostPath:
           path: /lib/modules
           type: Directory
@@ -162,6 +158,10 @@ spec:
           path: /etc/os-release
           type: File
         name: os-release-path
+      - hostPath:
+          path: /usr/src
+          type: Directory
+        name: usr-src-path
       - hostPath:
           path: /etc/apparmor.d
           type: DirectoryOrCreate