Add simple API for token assignment reporting.

lib/libcryptsetup.h

@@ -1782,6 +1782,21 @@ int crypt_token_unassign_keyslot(struct crypt_device *cd,
 	int token,
 	int keyslot);
 
+/**
+ * Get info about token assignment to particular keyslot.
+ *
+ * @param cd crypt device handle
+ * @param token token id
+ * @param keyslot keyslot
+ *
+ * @return 0 on success (token exists and is assigned to the keyslot),
+ *	   -ENOENT if token is not assigned to a keyslot (token, keyslot
+ *	   or both may be inactive) or other negative errno otherwise.
+ */
+int crypt_token_is_assigned(struct crypt_device *cd,
+	int token,
+	int keyslot);
+
 /**
  * Token handler open function prototype.
  * This function retrieves password from a token and return allocated buffer

lib/libcryptsetup.sym

@@ -43,6 +43,7 @@ CRYPTSETUP_2.0 {
 		crypt_token_luks2_keyring_set;
 		crypt_token_assign_keyslot;
 		crypt_token_unassign_keyslot;
+		crypt_token_is_assigned;
 		crypt_token_register;
 
 		crypt_activate_by_token;

lib/luks2/luks2.h

@@ -206,6 +206,11 @@ int LUKS2_token_assign(struct crypt_device *cd,
 	int assign,
 	int commit);
 
+int LUKS2_token_is_assigned(struct crypt_device *cd,
+	struct luks2_hdr *hdr,
+	int keyslot,
+	int token);
+
 int LUKS2_token_create(struct crypt_device *cd,
 	struct luks2_hdr *hdr,
 	int token,

lib/luks2/luks2_token.c

@@ -571,3 +571,27 @@ int LUKS2_token_assign(struct crypt_device *cd, struct luks2_hdr *hdr,
 
 	return token;
 }
+
+int LUKS2_token_is_assigned(struct crypt_device *cd, struct luks2_hdr *hdr,
+			    int keyslot, int token)
+{
+	int i;
+	json_object *jobj_token, *jobj_token_keyslots, *jobj;
+
+	if (keyslot < 0 || keyslot >= LUKS2_KEYSLOTS_MAX || token < 0 || token >= LUKS2_TOKENS_MAX)
+		return -EINVAL;
+
+	jobj_token = LUKS2_get_token_jobj(hdr, token);
+	if (!jobj_token)
+		return -ENOENT;
+
+	json_object_object_get_ex(jobj_token, "keyslots", &jobj_token_keyslots);
+
+	for (i = 0; i < (int) json_object_array_length(jobj_token_keyslots); i++) {
+		jobj = json_object_array_get_idx(jobj_token_keyslots, i);
+		if (keyslot == atoi(json_object_get_string(jobj)))
+			return 0;
+	}
+
+	return -ENOENT;
+}

lib/setup.c

@@ -4274,6 +4274,16 @@ int crypt_token_unassign_keyslot(struct crypt_device *cd, int token, int keyslot
 	return LUKS2_token_assign(cd, &cd->u.luks2.hdr, keyslot, token, 0, 1);
 }
 
+int crypt_token_is_assigned(struct crypt_device *cd, int token, int keyslot)
+{
+	int r;
+
+	if ((r = _onlyLUKS2(cd, CRYPT_CD_QUIET | CRYPT_CD_UNRESTRICTED)))
+		return r;
+
+	return LUKS2_token_is_assigned(cd, &cd->u.luks2.hdr, keyslot, token);
+}
+
 /* Internal only */
 int crypt_metadata_locking_enabled(void)
 {