SETPRIV(1) User Commands SETPRIV(1)
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(1) 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.
OPTION
--clear-groups
Clear supplementary groups.
-d, --dump
Dump current privilege state. 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... or --ambient-caps (+|-)cap... or --bound-
ing-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. If you drop
something 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 initgroups(3). Only use-
ful 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 AppAr-
mor, 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 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 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_se-
tuid_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 no-
tably 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(1) to
abort if SELinux is not in use, and the transition may be ig-
nored or cause execve(2) to fail at SELinux's whim. (In partic-
ular, 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(1) to abort if AppArmor
is not in use, and the transition may be ignored or cause ex-
ecve(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/lo-
cal/bin:/bin:/usr/bin for a regual user and to /usr/lo-
cal/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 code 127.
Be careful with this tool -- it may have unexpected security conse-
quences. 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.
EXAMPLE
If you're looking for behaviour 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
SEE ALSO
runuser(1), su(1), prctl(2), capabilities(7)
AUTHOR
Andy Lutomirski <luto@amacapital.net>
AVAILABILITY
The setpriv command is part of the util-linux package and is available
from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils/util-
linux/>.
util-linux July 2014 SETPRIV(1)