capng_change_id(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | SEE ALSO | AUTHOR | COLOPHON

CAPNG_CHANGE_ID(3)            Libcap-ng API            CAPNG_CHANGE_ID(3)

NAME         top

       capng_change_id - change the credentials retaining capabilities

SYNOPSIS         top

       #include <cap-ng.h>

       int capng_change_id(int uid, int gid, capng_flags_t flag);

DESCRIPTION         top

       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.

RETURN VALUE         top

       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.

SEE ALSO         top

       capng_update(3), capng_apply(3), prctl(2), capabilities(7)

AUTHOR         top

       Steve Grubb

COLOPHON         top

       This page is part of the libcap-ng (capabilities commands and
       library (NG)) project.  Information about the project can be found
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Red Hat                          Feb 2018              CAPNG_CHANGE_ID(3)