cmd/fscrypt: don't load protector in remove-protector-from-policy

Make remove-protector-from-policy work even if the protector cannot be
loaded (for example, due to having been deleted already).

Fixes https://github.com/google/fscrypt/issues/258
Fixes https://github.com/google/fscrypt/issues/272

2 files changed, 10 insertions, 9 deletions

diff --git a/actions/policy.go b/actions/policy.go
index 6c48117..7204380 100644
--- a/actions/policy.go
+++ b/actions/policy.go
@@ -461,14 +461,15 @@ func (policy *Policy) AddProtector(protector *Protector) error {
 }
 
 // RemoveProtector updates the data that is wrapping the Policy Key so that the
-// provided Protector is no longer protecting the specified Policy. If an error
-// is returned, no data has been changed. Note that no protector links are
+// protector with the given descriptor is no longer protecting the specified
+// Policy.  If an error is returned, no data has been changed.  Note that the
+// protector itself won't be removed, nor will a link to the protector be
 // removed (in the case where the protector and policy are on different
-// filesystems). The policy and protector can be locked or unlocked.
-func (policy *Policy) RemoveProtector(protector *Protector) error {
-	idx, ok := policy.findWrappedKeyIndex(protector.Descriptor())
+// filesystems).  The policy can be locked or unlocked.
+func (policy *Policy) RemoveProtector(protectorDescriptor string) error {
+	idx, ok := policy.findWrappedKeyIndex(protectorDescriptor)
 	if !ok {
-		return &ErrNotProtected{policy.Descriptor(), protector.Descriptor()}
+		return &ErrNotProtected{policy.Descriptor(), protectorDescriptor}
 	}
 
 	if len(policy.data.WrappedPolicyKeys) == 1 {
diff --git a/actions/policy_test.go b/actions/policy_test.go
index 11c9c3e..07943b8 100644
--- a/actions/policy_test.go
+++ b/actions/policy_test.go
@@ -114,7 +114,7 @@ func TestPolicyGoodRemoveProtector(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	err = pol.RemoveProtector(pro1)
+	err = pol.RemoveProtector(pro1.Descriptor())
 	if err != nil {
 		t.Error(err)
 	}
@@ -135,11 +135,11 @@ func TestPolicyBadRemoveProtector(t *testing.T) {
 	}
 	defer cleanupProtector(pro2)
 
-	if pol.RemoveProtector(pro2) == nil {
+	if pol.RemoveProtector(pro2.Descriptor()) == nil {
 		t.Error("we should not be able to remove a protector we did not add")
 	}
 
-	if pol.RemoveProtector(pro1) == nil {
+	if pol.RemoveProtector(pro1.Descriptor()) == nil {
 		t.Error("we should not be able to remove all the protectors from a policy")
 	}
 }