mail-crypt: mail_crypt_mailbox_allocated() - Force cross-user copies to (de,re)encryp...

diff --git a/src/plugins/mail-crypt/mail-crypt-plugin.c b/src/plugins/mail-crypt/mail-crypt-plugin.c
index 21da3481f26f6be2ff4caef45240f40c5533b85a..69c3b5903f54e27c9487f8e512e2b62cf0fbd636 100644 (file)
--- a/src/plugins/mail-crypt/mail-crypt-plugin.c
+++ b/src/plugins/mail-crypt/mail-crypt-plugin.c
@@ -336,11 +336,32 @@ mail_crypt_mail_save_begin(struct mail_save_context *ctx,
 static int
 mail_crypt_mailbox_copy(struct mail_save_context *ctx, struct mail *mail)
 {
-       struct mail_crypt_mailbox *mbox = MAIL_CRYPT_CONTEXT(ctx->transaction->box);
+       struct mailbox *dest_box = ctx->transaction->box;
+       struct mail_crypt_mailbox *mbox = MAIL_CRYPT_CONTEXT(dest_box);
+       struct mail_crypt_user *muser =
+               MAIL_CRYPT_USER_CONTEXT(dest_box->storage->user);
+
+       bool raw_copy;
+       if (mailbox_backends_equal(dest_box, mail->box)) {
+               /* Copy to same box always have identical crypt profile */
+               raw_copy = TRUE;
+       } else if (strcmp(dest_box->storage->user->username,
+                         mail->box->storage->user->username) != 0) {
+               /* Always consider copies between different users unsafe
+                  as they may have different encryption level and/or
+                  different global keys */
+               raw_copy = FALSE;
+       } else {
+               /* Within same user, consider safe only the case where
+                  encryption is enabled and keys are global. */
+               raw_copy = muser != NULL &&
+                          muser->save_version != 0 &&
+                          muser->global_keys.public_key != NULL;
+       }
 
-       if (ctx->transaction->box != mail->box)
-               return mail_storage_copy(ctx, mail);
-       return mbox->module_ctx.super.copy(ctx, mail);
+       return raw_copy ?
+              mbox->module_ctx.super.copy(ctx, mail) :
+              mail_storage_copy(ctx, mail);
 }
 
 static void mail_crypt_mailbox_close(struct mailbox *box)
@@ -373,14 +394,8 @@ static void mail_crypt_mailbox_allocated(struct mailbox *box)
 
        if ((class_flags & MAIL_STORAGE_CLASS_FLAG_BINARY_DATA) != 0) {
                v->save_begin = mail_crypt_mail_save_begin;
+               v->copy = mail_crypt_mailbox_copy;
 
-               /* if global keys are used, re-encrypting on copy/move
-                  is not necessary, so do not attempt to do it.
-                  with per-folder keys, emails must be re-encrypted
-                  when moving to another folder */
-               if (muser == NULL || muser->save_version == 0 ||
-                   muser->global_keys.public_key == NULL)
-                       v->copy = mail_crypt_mailbox_copy;
                if (muser == NULL || muser->save_version == 0)
                        v->save_finish = mail_crypt_mail_save_finish;
        }