Use lsblk to safeguard against outdated symlinks

Signed-off-by: Connor Catlett <[email protected]>

pkg/driver/node_linux.go

@@ -22,7 +22,9 @@ package driver
 import (
 	"fmt"
 	"os"
+	"os/exec"
 	"path/filepath"
+	"regexp"
 	"strconv"
 	"strings"
 
@@ -47,6 +49,7 @@ func (d *nodeService) appendPartition(devicePath, partition string) string {
 // if the device is not nvme, return the path directly
 // if the device is nvme, finds and returns the nvme device path eg. /dev/nvme1n1
 func (d *nodeService) findDevicePath(devicePath, volumeID, partition string) (string, error) {
+	strippedVolumeName := strings.Replace(volumeID, "-", "", -1)
 	canonicalDevicePath := ""
 
 	// If the given path exists, the device MAY be nvme. Further, it MAY be a
@@ -76,6 +79,9 @@ func (d *nodeService) findDevicePath(devicePath, volumeID, partition string) (st
 		}
 
 		klog.V(5).InfoS("[Debug] The canonical device path was resolved", "devicePath", devicePath, "cacanonicalDevicePath", canonicalDevicePath)
+		if err = verifyVolumeSerialMatch(canonicalDevicePath, strippedVolumeName, execRunner); err != nil {
+			return "", err
+		}
 		return d.appendPartition(canonicalDevicePath, partition), nil
 	}
 
@@ -87,13 +93,16 @@ func (d *nodeService) findDevicePath(devicePath, volumeID, partition string) (st
 	// which AWS presents NVME devices under /dev/disk/by-id/. For example,
 	// vol-0fab1d5e3f72a5e23 creates a symlink at
 	// /dev/disk/by-id/nvme-Amazon_Elastic_Block_Store_vol0fab1d5e3f72a5e23
-	nvmeName := "nvme-Amazon_Elastic_Block_Store_" + strings.Replace(volumeID, "-", "", -1)
+	nvmeName := "nvme-Amazon_Elastic_Block_Store_" + strippedVolumeName
 
 	nvmeDevicePath, err := findNvmeVolume(d.deviceIdentifier, nvmeName)
 
 	if err == nil {
 		klog.V(5).InfoS("[Debug] successfully resolved", "nvmeName", nvmeName, "nvmeDevicePath", nvmeDevicePath)
 		canonicalDevicePath = nvmeDevicePath
+		if err = verifyVolumeSerialMatch(canonicalDevicePath, strippedVolumeName, execRunner); err != nil {
+			return "", err
+		}
 		return d.appendPartition(canonicalDevicePath, partition), nil
 	} else {
 		klog.V(5).InfoS("[Debug] error searching for nvme path", "nvmeName", nvmeName, "err", err)
@@ -116,6 +125,37 @@ func (d *nodeService) findDevicePath(devicePath, volumeID, partition string) (st
 	return canonicalDevicePath, nil
 }
 
+// Helper to inject exec.Comamnd().CombinedOutput() for verifyVolumeSerialMatch
+// Tests use a mocked version that does not actually execute any binaries
+func execRunner(name string, arg ...string) ([]byte, error) {
+	return exec.Command(name, arg...).CombinedOutput()
+}
+
+func verifyVolumeSerialMatch(canonicalDevicePath string, strippedVolumeName string, execRunner func(string, ...string) ([]byte, error)) error {
+	// In some rare cases, a race condition can lead to the /dev/disk/by-id/ symlink becoming out of date
+	// See https://github.com/kubernetes-sigs/aws-ebs-csi-driver/issues/1224 for more info
+	// Attempt to use lsblk to double check that the nvme device selected was the correct volume
+	output, err := execRunner("lsblk", "--noheadings", "--ascii", "--nodeps", "--output", "SERIAL", canonicalDevicePath)
+
+	if err == nil {
+		// Look for an EBS volume ID in the output, compare all matches against what we expect
+		// (in some rare cases there may be multiple matches due to lsblk printing partitions)
+		// If no volume ID is in the output (non-Nitro instances, SBE devices, etc) silently proceed
+		volumeRegex := regexp.MustCompile(`vol[a-z0-9]+`)
+		for _, volume := range volumeRegex.FindAllString(string(output), -1) {
+			klog.V(6).InfoS("Comparing volume serial", "canonicalDevicePath", canonicalDevicePath, "expected", strippedVolumeName, "actual", volume)
+			if volume != strippedVolumeName {
+				return fmt.Errorf("Refusing to mount %s because it claims to be %s but should be %s", canonicalDevicePath, volume, strippedVolumeName)
+			}
+		}
+	} else {
+		// If the command fails (for example, because lsblk is not available), silently ignore the error and proceed
+		klog.V(5).ErrorS(err, "Ignoring lsblk failure", "canonicalDevicePath", canonicalDevicePath, "strippedVolumeName", strippedVolumeName)
+	}
+
+	return nil
+}
+
 func errNoDevicePathFound(devicePath, volumeID string) error {
 	return fmt.Errorf("no device path for device %q volume %q found", devicePath, volumeID)
 }

pkg/driver/node_linux_test.go

@@ -20,6 +20,7 @@ limitations under the License.
 package driver
 
 import (
+	"fmt"
 	"io/fs"
 	"os"
 	"testing"
@@ -190,6 +191,69 @@ func TestFindDevicePath(t *testing.T) {
 	}
 }
 
+const fakeVolumeName = "vol11111111111111111"
+const fakeIncorrectVolumeName = "vol21111111111111111"
+
+func TestVerifyVolumeSerialMatch(t *testing.T) {
+	type testCase struct {
+		name        string
+		execOutput  string
+		execError   error
+		expectError bool
+	}
+	testCases := []testCase{
+		{
+			name: "success: empty",
+			execOutput: "",
+		},
+		{
+			name: "success: single",
+			execOutput: fakeVolumeName,
+		},
+		{
+			name: "success: multiple",
+			execOutput: fakeVolumeName + "\n" + fakeVolumeName + "\n" + fakeVolumeName,
+		},
+		{
+			name: "success: whitespace",
+			execOutput: "\t     " + fakeVolumeName + "         \n    \t    ",
+		},
+		{
+			name: "success: extra output",
+			execOutput: "extra output without name in it\n" + fakeVolumeName,
+		},
+		{
+			name: "success: failed command",
+			execError: fmt.Errorf("Exec failed"),
+		},
+		{
+			name: "failure: wrong volume",
+			execOutput: fakeIncorrectVolumeName,
+			expectError: true,
+		},
+		{
+			name: "failure: mixed",
+			execOutput: fakeVolumeName + "\n" + fakeIncorrectVolumeName,
+			expectError: true,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			mockExecRunner := func(_ string, _ ...string) ([]byte, error) {
+				return []byte(tc.execOutput), tc.execError
+			}
+
+			result := verifyVolumeSerialMatch("path", fakeVolumeName, mockExecRunner)
+			if tc.expectError {
+				assert.Error(t, result)
+			} else {
+				assert.NoError(t, result)
+			}
+		})
+	}
+}
+
 type fakeFileInfo struct {
 	name string
 	mode os.FileMode