NAME

       setpriv - run a program with different Linux privilege settings

SYNOPSIS

       setpriv [options] program [arguments]

DESCRIPTION

       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

       --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

       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

       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

       Andy Lutomirski <luto@amacapital.net>

SEE ALSO

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

REPORTING BUGS

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

AVAILABILITY

       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/>.