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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | SEE ALSO | AUTHOR | COLOPHON |
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CAPNG_CHANGE_ID(3) Libcap-ng API CAPNG_CHANGE_ID(3)
capng_change_id - change the credentials retaining capabilities
#include <cap-ng.h>
int capng_change_id(int uid, int gid, capng_flags_t flag);
This function will change uid and gid to the ones given while
retaining the capabilities previously specified in capng_update.
It is also possible to specify -1 for either the uid or gid in
which case the function will not change the uid or gid and leave
it "as is". This is useful if you just want the flag options to be
applied (assuming the option doesn't require more privileges that
you currently have).
It is not necessary and perhaps better if capng_apply has not been
called prior to this function so that all necessary privileges are
still intact. The caller may be required to have CAP_SETPCAP
capability still active before calling this function or
capabilities cannot be changed.
This function also takes a flag parameter that helps to tailor the
exact actions performed by the function to secure the environment.
The option may be or'ed together. The legal values are:
CAPNG_NO_FLAG
Simply change uid and retain specified capabilities
and that's all.
CAPNG_DROP_SUPP_GRP
After changing id, remove any supplement groups that
may still be in effect from the old uid.
CAPNG_INIT_SUPP_GRP
After changing id, initialize any supplement groups
that may come with the new account. If given with
CAPNG_DROP_SUPP_GRP it will have no effect.
CAPNG_CLEAR_BOUNDING
Clear the bounding set regardless to the internal
representation already setup prior to changing the
uid/gid.
CAPNG_CLEAR_AMBIENT
Clear ambient capabilities regardless of the
internal representation already setup prior to
changing the uid/gid.
This returns 0 on success and a negative number on failure.
-1 means capng has not been initted properly
-2 means a failure requesting to keep capabilities across
the uid change
-3 means that applying the intermediate capabilities failed
-4 means changing gid failed
-5 means dropping supplemental groups failed
-6 means changing the uid failed
-7 means dropping the ability to retain caps across a uid
change failed
-8 means clearing the bounding set failed
-9 means dropping CAP_SETPCAP or ambient capabilities
failed
-10 means initializing supplemental groups failed
Note: the only safe action to do upon failure of this function is
to probably exit. This is because you are likely in a situation
with partial permissions and not what you intended.
capng_update(3), capng_apply(3), prctl(2), capabilities(7)
Steve Grubb
This page is part of the libcap-ng (capabilities commands and
library (NG)) project. Information about the project can be found
at ⟨https://people.redhat.com/sgrubb/libcap-ng/⟩. It is not known
how to report bugs for this man page; if you know, please send a
mail to man-pages@man7.org. This page was obtained from the
tarball fetched from
⟨https://people.redhat.com/sgrubb/libcap-ng/index.html⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Red Hat Feb 2018 CAPNG_CHANGE_ID(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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