[uki] Wait for oem to appear after encryption (#216)

internal/agent/hooks/kcrypt_uki.go

@@ -1,6 +1,7 @@
 package hook
 
 import (
+	"fmt"
 	"os"
 	"strconv"
 	"strings"
@@ -96,10 +97,40 @@ func (k KcryptUKI) Run(c config.Config, _ v1.Spec) error {
 		c.Logger.Infof("Done encrypting %s", p)
 	}
 
+	_, _ = utils.SH("sync")
+
 	err = kcrypt.UnlockAll(true)
 	if err != nil {
 		return err
 	}
+	// Close the unlocked partitions after dealing with them, otherwise we leave them open and they can be mounted by anyone
+	defer func() {
+		for _, p := range append([]string{"COS_OEM", "COS_PERSISTENT"}, c.Install.Encrypt...) {
+			c.Logger.Debugf("Closing unencrypted /dev/disk/by-label/%s", p)
+			out, err := utils.SH(fmt.Sprintf("cryptsetup close /dev/disk/by-label/%s", p))
+			// There is a known error with cryptsetup that it can't close the device because of a semaphore
+			// doesnt seem to affect anything as the device is closed as expected so we ignore it if it matches the
+			// output of the error
+			if err != nil && !strings.Contains(out, "incorrect semaphore state") {
+				c.Logger.Errorf("could not close /dev/disk/by-label/%s: %s", p, out)
+			}
+		}
+	}()
+
+	// Here it can take the oem partition a bit of time to appear after unlocking so we need to retry a couple of time with some waiting
+	// retry + backoff
+	for i := 0; i < 10; i++ {
+		c.Logger.Infof("Waiting for unlocked partition to appear")
+		_, _ = utils.SH("sync")
+		part, _ := utils.SH("blkid -L COS_OEM")
+		if part == "" {
+			c.Logger.Infof("Partition not found, waiting %d seconds before retrying", i)
+			time.Sleep(time.Duration(i) * time.Second)
+			continue
+		}
+		c.Logger.Infof("Partition found, continuing")
+		break
+	}
 	err = machine.Mount("COS_OEM", constants.OEMDir)
 	if err != nil {
 		return err
@@ -108,7 +139,7 @@ func (k KcryptUKI) Run(c config.Config, _ v1.Spec) error {
 	if err != nil {
 		return err
 	}
-	err = machine.Umount(constants.OEMDir) //nolint:errcheck
+	err = machine.Umount(constants.OEMDir)
 	if err != nil {
 		return err
 	}