cred: Hide internal flag CRED_FLAG_CAPMODE

[olce]

Summary

This flag is used in field 'cr_flags', which is never directly visible
outside the kernel. That field is however exported through 'struct
kinfo_proc' objects (field 'ki_cr_flags'), either from the kernel via
sysctls or from libkvm, and is supposed to contain exported flags
prefixed with KI_CRF_ (currently, KI_CRF_CAPABILITY_MODE and
KI_CRF_GRP_OVERFLOW, this second one being a purely userland one
signaling overflow of 'ki_groups').

Make sure that KI_CRF_CAPABILITY_MODE is the flag actually exported and
tested by userland programs, and hide the internal CRED_FLAG_CAPMODE.
As both flags are currently defined to the same value, this doesn't
change the KBI, but of course does change the KPI. A code search via
GitHub and Google fortunately doesn't reveal any outside uses for
CRED_FLAG_CAPMODE.

[mhorne]

LGTM with one question. Seems fine to break the KPI here when the kinfo_getproc(3) page basically says "read sys/user.h for documentation of the structure's fields".

lib/libkvm/kvm_proc.c

159–160

Not your fault but this assignment is weird here, and should appear above ki_ruid, no?

sys/sys/ucred.h

42

Is it intentional that you are also hiding this declaration?

[olce]

lib/libkvm/kvm_proc.c

159–160

Yes, not my fault. ;-) It is so small a change that I'll move that line up in the same commit.

sys/sys/ucred.h

42

Yes, nothing in this header references struct loginclass except struct ucred.

[mhorne]

sys/sys/ucred.h

42

👍

[olce]

Moved up the assignment of ki_uid in my tree.