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 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.
-h, --help
Display help text and exit.
-V, --version
Print version 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/util-linux/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/>.
util-linux 2.38.1 2022-05-11 SETPRIV(1)
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