SETPRIV
Section: User Commands (1)
Updated: July 2014
Page Index
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... or --ambient-caps (+|-)cap... or --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
initgroups(3).
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 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
AUTHORS
Andy Lutomirski
SEE ALSO
runuser(1),
su(1),
prctl(2),
capabilities(7)
AVAILABILITY
The
setpriv
command is part of the util-linux package and is available from
Linux Kernel Archive