.TH "CAPNG_LOCK" "3" "Mar 2026" "Red Hat" "Libcap-ng API"
.SH NAME
capng_lock \- lock the current process capabilities settings
.SH "SYNOPSIS"
.B #include <cap-ng.h>
.sp
int capng_lock(void);

.SH "DESCRIPTION"

capng_lock will take steps to prevent children of the current process
to regain full privileges if the uid is 0. This should be called while
possessing the CAP_SETPCAP capability in the kernel. This function will
do the following if permitted by the kernel:
.IP \[bu] 2
Set the NOROOT option on for PR_SET_SECUREBITS.
.IP \[bu] 2
Set the NOROOT_LOCKED option to on for PR_SET_SECUREBITS.
.IP \[bu] 2
Set the PR_NO_SETUID_FIXUP option on for PR_SET_SECUREBITS.
.IP \[bu] 2
Set the PR_NO_SETUID_FIXUP_LOCKED option on for PR_SET_SECUREBITS.
.PP
It does not enable PR_SET_KEEPCAPS or the KEEP_CAPS/KEEP_CAPS_LOCKED
securebits. Existing securebits set by the caller are preserved, including
securebits that were added after this version of libcap-ng was built.


.SH "RETURN VALUE"

This returns 0 on success and a negative number on failure. -1 means a failure
reading or updating the securebits. -2 means failure setting
PR_SET_NO_NEW_PRIVS. These are additive meaning -3 is a failure of both.

.SH "SEE ALSO"

.BR capng_apply (3),
.BR prctl (2),
.BR capabilities (7)

.SH AUTHOR
Steve Grubb