leases_db: Make leases_db_rename atomic

Do the rename under one lock to protect against potential races while
we don't hold it.

Factor out the NDR marshalling into leases_db_do_locked(), leaving the
rename function pretty simple.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>

diff --git a/source3/locking/leases_db.c b/source3/locking/leases_db.c
index 31576280fb63398d7c60605c3368118635456036..51cd54a1e91c2fd5cedb7ab04cf8e7cd04c5cea0 100644 (file)
--- a/source3/locking/leases_db.c
+++ b/source3/locking/leases_db.c
@@ -86,6 +86,114 @@ static TDB_DATA leases_db_key(struct leases_db_key_buf *buf,
        return (TDB_DATA) { .dptr = buf->buf, .dsize = sizeof(buf->buf) };
 }
 
+struct leases_db_do_locked_state {
+       void (*fn)(struct leases_db_value *value,
+                  bool *modified,
+                  void *private_data);
+       void *private_data;
+       NTSTATUS status;
+};
+
+static void leases_db_do_locked_fn(struct db_record *rec, void *private_data)
+{
+       struct leases_db_do_locked_state *state = private_data;
+       TDB_DATA db_value = dbwrap_record_get_value(rec);
+       DATA_BLOB blob = { .data = db_value.dptr, .length = db_value.dsize };
+       struct leases_db_value *value = NULL;
+       enum ndr_err_code ndr_err;
+       bool modified = false;
+
+       value = talloc_zero(talloc_tos(), struct leases_db_value);
+       if (value == NULL) {
+               state->status = NT_STATUS_NO_MEMORY;
+               goto done;
+       }
+
+       if (blob.length != 0) {
+               ndr_err = ndr_pull_struct_blob_all(
+                       &blob,
+                       value,
+                       value,
+                       (ndr_pull_flags_fn_t)ndr_pull_leases_db_value);
+               if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+                       DBG_DEBUG("ndr_pull_struct_blob_failed: %s\n",
+                                 ndr_errstr(ndr_err));
+                       state->status = ndr_map_error2ntstatus(ndr_err);
+                       goto done;
+               }
+       }
+
+       state->fn(value, &modified, state->private_data);
+
+       if (!modified) {
+               goto done;
+       }
+
+       if (value->num_files == 0) {
+               state->status = dbwrap_record_delete(rec);
+               if (!NT_STATUS_IS_OK(state->status)) {
+                       DBG_DEBUG("dbwrap_record_delete returned %s\n",
+                                 nt_errstr(state->status));
+               }
+               goto done;
+       }
+
+       ndr_err = ndr_push_struct_blob(
+               &blob,
+               value,
+               value,
+               (ndr_push_flags_fn_t)ndr_push_leases_db_value);
+       if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+               DBG_DEBUG("ndr_push_struct_blob_failed: %s\n",
+                         ndr_errstr(ndr_err));
+               state->status = ndr_map_error2ntstatus(ndr_err);
+               goto done;
+       }
+
+       if (DEBUGLEVEL >= 10) {
+               DBG_DEBUG("\n");
+               NDR_PRINT_DEBUG(leases_db_value, value);
+       }
+
+       db_value = make_tdb_data(blob.data, blob.length);
+
+       state->status = dbwrap_record_store(rec, db_value, 0);
+       if (!NT_STATUS_IS_OK(state->status)) {
+               DBG_DEBUG("dbwrap_record_store returned %s\n",
+                         nt_errstr(state->status));
+       }
+
+done:
+       TALLOC_FREE(value);
+}
+
+static NTSTATUS leases_db_do_locked(
+       const struct GUID *client_guid,
+       const struct smb2_lease_key *lease_key,
+       void (*fn)(struct leases_db_value *value,
+                  bool *modified,
+                  void *private_data),
+       void *private_data)
+{
+       struct leases_db_key_buf keybuf;
+       TDB_DATA db_key = leases_db_key(&keybuf, client_guid, lease_key);
+       struct leases_db_do_locked_state state = {
+               .fn = fn, .private_data = private_data,
+       };
+       NTSTATUS status;
+
+       if (!leases_db_init(false)) {
+               return NT_STATUS_INTERNAL_ERROR;
+       }
+
+       status = dbwrap_do_locked(
+               leases_db, db_key, leases_db_do_locked_fn, &state);
+       if (!NT_STATUS_IS_OK(status)) {
+               return status;
+       }
+       return state.status;
+}
+
 NTSTATUS leases_db_add(const struct GUID *client_guid,
                       const struct smb2_lease_key *lease_key,
                       const struct file_id *id,
@@ -381,6 +489,40 @@ NTSTATUS leases_db_parse(const struct GUID *client_guid,
        return state.status;
 }
 
+struct leases_db_rename_state {
+       const struct file_id *id;
+       const char *servicename_new;
+       const char *filename_new;
+       const char *stream_name_new;
+       NTSTATUS status;
+};
+
+static void leases_db_rename_fn(
+       struct leases_db_value *value, bool *modified, void *private_data)
+{
+       struct leases_db_rename_state *state = private_data;
+       struct leases_db_file *file = NULL;
+       uint32_t i;
+
+       /* id must exist. */
+       for (i = 0; i < value->num_files; i++) {
+               if (file_id_equal(state->id, &value->files[i].id)) {
+                       break;
+               }
+       }
+       if (i == value->num_files) {
+               state->status = NT_STATUS_NOT_FOUND;
+               return;
+       }
+
+       file = &value->files[i];
+       file->servicepath = state->servicename_new;
+       file->base_name = state->filename_new;
+       file->stream_name = state->stream_name_new;
+
+       *modified = true;
+}
+
 NTSTATUS leases_db_rename(const struct GUID *client_guid,
                       const struct smb2_lease_key *lease_key,
                       const struct file_id *id,
@@ -388,21 +530,22 @@ NTSTATUS leases_db_rename(const struct GUID *client_guid,
                       const char *filename_new,
                       const char *stream_name_new)
 {
+       struct leases_db_rename_state state = {
+               .id = id,
+               .servicename_new = servicename_new,
+               .filename_new = filename_new,
+               .stream_name_new = stream_name_new,
+       };
        NTSTATUS status;
 
-       status = leases_db_del(client_guid,
-                               lease_key,
-                               id);
+       status = leases_db_do_locked(
+               client_guid, lease_key, leases_db_rename_fn, &state);
        if (!NT_STATUS_IS_OK(status)) {
+               DBG_DEBUG("leases_db_do_locked failed: %s\n",
+                         nt_errstr(status));
                return status;
        }
-
-       return leases_db_add(client_guid,
-                               lease_key,
-                               id,
-                               servicename_new,
-                               filename_new,
-                               stream_name_new);
+       return state.status;
 }
 
 NTSTATUS leases_db_copy_file_ids(TALLOC_CTX *mem_ctx,