From gkd-capability.c:
This program needs the CAP_IPC_LOCK posix capability.
We want to allow either setuid root or file system based capabilies
to work. If file system based capabilities, this is a no-op unless
the root user is running the program. In that case we just drop
capabilities down to IPC_LOCK. If we are setuid root, then change to the
invoking user retaining just the IPC_LOCK capability. The application
is aborted if for any reason we are unable to drop privileges.
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