setpriv(1) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | NOTES | EXAMPLES | AUTHORS | SEE ALSO | REPORTING BUGS | AVAILABILITY

SETPRIV(1)                    User Commands                   SETPRIV(1)

NAME         top

       setpriv - run a program with different Linux privilege settings

SYNOPSIS         top

       setpriv [options] program [arguments]

DESCRIPTION         top

       Sets or queries various Linux privilege settings that are
       inherited across execve(2).

       In comparison to su(1) and runuser(1), setpriv neither uses PAM,
       nor does it prompt for a password. It is a simple,
       non-set-user-ID wrapper around execve(2), and can be used to drop
       privileges in the same way as setuidgid(8) from daemontools,
       chpst(8) from runit, or similar tools shipped by other service
       managers.

OPTIONS         top

       --clear-groups
           Clear supplementary groups.

       -d, --dump
           Dump the current privilege state. This option can be
           specified more than once to show extra, mostly useless,
           information. Incompatible with all other options.

       --groups group...
           Set supplementary groups. The argument is a comma-separated
           list of GIDs or names.

       --inh-caps (+|-)cap..., --ambient-caps (+|-)cap...,
       --bounding-set (+|-)cap...
           Set the inheritable capabilities, ambient capabilities or the
           capability bounding set. See capabilities(7). The argument is
           a comma-separated list of +cap and -cap entries, which add or
           remove an entry respectively. cap can either be a
           human-readable name as seen in capabilities(7) without the
           cap_ prefix or of the format cap_N, where N is the internal
           capability index used by Linux. +all and -all can be used to
           add or remove all caps.

           The set of capabilities starts out as the current inheritable
           set for --inh-caps, the current ambient set for
           --ambient-caps and the current bounding set for
           --bounding-set.

           Note the following restrictions (detailed in capabilities(7))
           regarding modifications to these capability sets:

           •   A capability can be added to the inheritable set only if
               it is currently present in the bounding set.

           •   A capability can be added to the ambient set only if it
               is currently present in both the permitted and
               inheritable sets.

           •   Notwithstanding the syntax offered by setpriv, the kernel
               does not permit capabilities to be added to the bounding
               set.

       If you drop a capability from the bounding set without also
       dropping it from the inheritable set, you are likely to become
       confused. Do not do that.

       --keep-groups
           Preserve supplementary groups. Only useful in conjunction
           with --rgid, --egid, or --regid.

       --init-groups
           Initialize supplementary groups using initgroups3. Only
           useful in conjunction with --ruid or --reuid.

       --list-caps
           List all known capabilities. This option must be specified
           alone.

       --no-new-privs
           Set the no_new_privs bit. With this bit set, execve(2) will
           not grant new privileges. For example, the set-user-ID and
           set-group-ID bits as well as file capabilities will be
           disabled. (Executing binaries with these bits set will still
           work, but they will not gain privileges. Certain LSMs,
           especially AppArmor, may result in failures to execute
           certain programs.) This bit is inherited by child processes
           and cannot be unset. See prctl(2) and
           Documentation/prctl/no_new_privs.txt in the Linux kernel
           source.

           The no_new_privs bit is supported since Linux 3.5.

       --rgid gid, --egid gid, --regid gid
           Set the real, effective, or both GIDs. The gid argument can
           be given as a textual group name.

           For safety, you must specify one of --clear-groups, --groups,
           --keep-groups, or --init-groups if you set any primary gid.

       --ruid uid, --euid uid, --reuid uid
           Set the real, effective, or both UIDs. The uid argument can
           be given as a textual login name.

           Setting a uid or gid does not change capabilities, although
           the exec call at the end might change capabilities. This
           means that, if you are root, you probably want to do
           something like:

           setpriv --reuid=1000 --regid=1000 --inh-caps=-all

       --securebits (+|-)securebit...
           Set or clear securebits. The argument is a comma-separated
           list. The valid securebits are noroot, noroot_locked,
           no_setuid_fixup, no_setuid_fixup_locked, and
           keep_caps_locked. keep_caps is cleared by execve(2) and is
           therefore not allowed.

       --pdeathsig keep|clear|<signal>
           Keep, clear or set the parent death signal. Some LSMs, most
           notably SELinux and AppArmor, clear the signal when the
           process' credentials change. Using --pdeathsig keep will
           restore the parent death signal after changing credentials to
           remedy that situation.

       --selinux-label label
           Request a particular SELinux transition (using a transition
           on exec, not dyntrans). This will fail and cause setpriv to
           abort if SELinux is not in use, and the transition may be
           ignored or cause execve(2) to fail at SELinux’s whim. (In
           particular, this is unlikely to work in conjunction with
           no_new_privs.) This is similar to runcon(1).

       --apparmor-profile profile
           Request a particular AppArmor profile (using a transition on
           exec). This will fail and cause setpriv to abort if AppArmor
           is not in use, and the transition may be ignored or cause
           execve(2) to fail at AppArmor’s whim.

       --reset-env
           Clears all the environment variables except TERM; initializes
           the environment variables HOME, SHELL, USER, LOGNAME
           according to the user’s passwd entry; sets PATH to
           /usr/local/bin:/bin:/usr/bin for a regular user and to
           /usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
           for root.

           The environment variable PATH may be different on systems
           where /bin and /sbin are merged into /usr. The environment
           variable SHELL defaults to /bin/sh if none is given in the
           user’s passwd entry.

       -V, --version
           Display version information and exit.

       -h, --help
           Display help text and exit.

NOTES         top

       If applying any specified option fails, program will not be run
       and setpriv will return with exit status 127.

       Be careful with this tool — it may have unexpected security
       consequences. For example, setting no_new_privs and then execing
       a program that is SELinux-confined (as this tool would do) may
       prevent the SELinux restrictions from taking effect.

EXAMPLES         top

       If you’re looking for behavior similar to su(1)/runuser(1), or
       sudo(8) (without the -g option), try something like:

       setpriv --reuid=1000 --regid=1000 --init-groups

       If you want to mimic daemontools' setuid(8), try:

       setpriv --reuid=1000 --regid=1000 --clear-groups

AUTHORS         top

       Andy Lutomirski <luto@amacapital.net>

SEE ALSO         top

       runuser(1), su(1), prctl(2), capabilities(7)

REPORTING BUGS         top

       For bug reports, use the issue tracker at
       https://github.com/karelzak/util-linux/issues.

AVAILABILITY         top

       The setpriv command is part of the util-linux package which can
       be downloaded from Linux Kernel Archive
       <https://www.kernel.org/pub/linux/utils/util-linux/>. This page
       is part of the util-linux (a random collection of Linux
       utilities) project. Information about the project can be found at
       ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you have
       a bug report for this manual page, send it to
       util-linux@vger.kernel.org. This page was obtained from the
       project's upstream Git repository
       ⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
       2021-08-27. (At that time, the date of the most recent commit
       that was found in the repository was 2021-08-24.) 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

util-linux 2.37.85-637cc       2021-04-02                     SETPRIV(1)

Pages that refer to this page: runuser(1)su(1)capabilities(7)credentials(7)