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containers: Enforce max_containers_per_user
Signed-off-by: Simon McVittie <smcv@collabora.com> Reviewed-by: Philip Withnall <withnall@endlessm.com> Bug: https://bugs.freedesktop.org/show_bug.cgi?id=101354
This commit is contained in:
Simon McVittie
parent
62e8fd7a9c
commit
4b4f2a89be
2 changed files with 72 additions and 3 deletions
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@ -85,6 +85,8 @@ struct BusContainers
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/* path borrowed from BusContainerInstance => unowned BusContainerInstance
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* The BusContainerInstance removes itself from here on destruction. */
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DBusHashTable *instances_by_path;
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/* uid => (void *) (uintptr_t) number of containers */
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DBusHashTable *n_containers_by_user;
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DBusString address_template;
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dbus_uint64_t next_container_id;
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};
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@ -190,6 +192,7 @@ bus_containers_unref (BusContainers *self)
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if (--self->refcount == 0)
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{
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_dbus_clear_hash_table (&self->instances_by_path);
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_dbus_clear_hash_table (&self->n_containers_by_user);
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_dbus_string_free (&self->address_template);
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dbus_free (self);
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@ -307,9 +310,26 @@ bus_container_instance_unref (BusContainerInstance *self)
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/* It's OK to do this even if we were never added to instances_by_path,
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* because the paths are globally unique. */
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if (self->path != NULL && self->containers->instances_by_path != NULL)
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_dbus_hash_table_remove_string (self->containers->instances_by_path,
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self->path);
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if (self->path != NULL && self->containers->instances_by_path != NULL &&
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_dbus_hash_table_remove_string (self->containers->instances_by_path,
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self->path))
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{
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DBusHashIter entry;
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uintptr_t n = 0;
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if (!_dbus_hash_iter_lookup (self->containers->n_containers_by_user,
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(void *) (uintptr_t) self->uid,
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FALSE, &entry))
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_dbus_assert_not_reached ("Container should not be placed in "
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"instances_by_path until its "
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"n_containers_by_user entry has "
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"been allocated");
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n = (uintptr_t) _dbus_hash_iter_get_value (&entry);
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_dbus_assert (n > 0);
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n -= 1;
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_dbus_hash_iter_set_value (&entry, (void *) n);
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}
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_dbus_clear_variant (&self->metadata);
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bus_context_unref (self->context);
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@ -664,6 +684,8 @@ bus_containers_handle_add_server (DBusConnection *connection,
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DBusMessage *reply = NULL;
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int metadata_size;
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int limit;
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DBusHashIter n_containers_by_user_entry;
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uintptr_t this_user_containers = 0;
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context = bus_transaction_get_context (transaction);
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containers = bus_context_get_containers (context);
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@ -811,6 +833,15 @@ bus_containers_handle_add_server (DBusConnection *connection,
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goto oom;
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}
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if (containers->n_containers_by_user == NULL)
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{
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containers->n_containers_by_user = _dbus_hash_table_new (DBUS_HASH_UINTPTR,
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NULL, NULL);
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if (containers->n_containers_by_user == NULL)
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goto oom;
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}
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limit = bus_context_get_max_containers (context);
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if (_dbus_hash_table_get_n_entries (containers->instances_by_path) >= limit)
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@ -829,10 +860,46 @@ bus_containers_handle_add_server (DBusConnection *connection,
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goto fail;
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}
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if (!_dbus_hash_iter_lookup (containers->n_containers_by_user,
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/* We statically assert that a uid fits in a
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* uintptr_t, so this can't lose information */
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(void *) (uintptr_t) instance->uid, TRUE,
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&n_containers_by_user_entry))
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goto oom;
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this_user_containers = (uintptr_t) _dbus_hash_iter_get_value (&n_containers_by_user_entry);
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limit = bus_context_get_max_containers_per_user (context);
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/* We need to be careful with types here because this_user_containers is
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* unsigned. */
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if (limit <= 0 || this_user_containers >= (unsigned) limit)
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{
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DBusError local_error = DBUS_ERROR_INIT;
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dbus_set_error (&local_error, DBUS_ERROR_LIMITS_EXCEEDED,
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"Connection \"%s\" (%s) is not allowed to create more "
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"container servers for uid %lu "
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"(max_containers_per_user=%d)",
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bus_connection_get_name (connection),
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bus_connection_get_loginfo (connection),
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instance->uid, limit);
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bus_context_log_literal (context, DBUS_SYSTEM_LOG_WARNING,
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local_error.message);
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dbus_move_error (&local_error, error);
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goto fail;
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}
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if (!_dbus_hash_table_insert_string (containers->instances_by_path,
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instance->path, instance))
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goto oom;
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/* This cannot fail (we already allocated the memory) so we can do it after
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* we already succeeded in adding it to instances_by_path. The matching
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* decrement is done whenever we remove it from instances_by_path. */
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this_user_containers += 1;
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_dbus_hash_iter_set_value (&n_containers_by_user_entry,
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(void *) this_user_containers);
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if (!_dbus_list_append (&creator_data->instances, instance))
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goto oom;
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@ -88,6 +88,7 @@ DBUS_PRIVATE_EXPORT
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void _dbus_hash_iter_remove_entry (DBusHashIter *iter);
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DBUS_PRIVATE_EXPORT
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void* _dbus_hash_iter_get_value (DBusHashIter *iter);
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DBUS_PRIVATE_EXPORT
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void _dbus_hash_iter_set_value (DBusHashIter *iter,
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void *value);
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DBUS_PRIVATE_EXPORT
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@ -96,6 +97,7 @@ DBUS_PRIVATE_EXPORT
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const char* _dbus_hash_iter_get_string_key (DBusHashIter *iter);
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DBUS_PRIVATE_EXPORT
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uintptr_t _dbus_hash_iter_get_uintptr_key (DBusHashIter *iter);
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DBUS_PRIVATE_EXPORT
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dbus_bool_t _dbus_hash_iter_lookup (DBusHashTable *table,
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void *key,
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dbus_bool_t create_if_not_found,
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