KCM: Add some forgotten NULL checks Several memory allocations across the KCM codebase did not check their result for NULL. This patch fixes that. Reviewed-by: Fabiano Fidêncio <fidencio@redhat.com>

KCM: Use the right memory context Inside the tevent request, we should use 'state' as the intermediate memory context and steal the result up to 'mem_ctx' on success. 'mem_ctx' itself should only be used to create the tevent_req as the first thing during the request creation. However, this bug is not very severe as the mem_ctx was always the KCM operation memory context, so the memory was freed when the operation terminated. Reviewed-by: Fabiano Fidêncio <fidencio@redhat.com>

KCM: Do not leak newly created ccache in case the name is malformed This is not a big deal as the mem_ctx parameter of the operation is typically just a short-lived operation context. Nonetheless, it is best practice to not rely on how the memory context is set up in utility functions. Reviewed-by: Fabiano Fidêncio <fidencio@redhat.com>

KCM: Make the secrets ccache back end configurable, make secrets the default Adds a new option 'ccache_storage' that allows to select either the memory back end or the secrets back end. The secrets back end is the default one and this option is even undocumented. Reviewed-by: Michal Židek <mzidek@redhat.com> Reviewed-by: Simo Sorce <simo@redhat.com>

KCM: Add a in-memory credential storage Implements a simple back end for the ccache module that lets the KCM server store credentials directly in memory. Reviewed-by: Michal Židek <mzidek@redhat.com> Reviewed-by: Simo Sorce <simo@redhat.com>

KCM: Implement an internal ccache storage and retrieval API In order for the KCM server to work with ccaches stored in different locations, implement a middle-man between the KCM server and the ccache storage. This module has asynchronous API because we can't assume anything about where the ccaches are stored. Reviewed-by: Michal Židek <mzidek@redhat.com> Reviewed-by: Simo Sorce <simo@redhat.com>