added pledge and unveil support

README.md

@@ -1,5 +1,5 @@
 # godrop - drop privileges
 
-Godrop is a simple library to drop privileges on linux maschines.
+Godrop is a simple library to drop privileges on Linux and OpenBSD maschines.
 
 See the examples directory on how to use the `Drop` and `MultiDrop` functions.

go.mod

@@ -1 +1,3 @@
 module git.giftfish.de/ston1th/godrop/v2
+
+require golang.org/x/sys v0.0.0-20181026144532-2772b66316d2 // indirect

go.sum

@@ -0,0 +1,2 @@
+golang.org/x/sys v0.0.0-20181026144532-2772b66316d2 h1:W7CqTdBJ1CmxLKe7LptKDnBYV6PHrVLiGnoyBjaG/JQ=
+golang.org/x/sys v0.0.0-20181026144532-2772b66316d2/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=

godrop.go

@@ -2,10 +2,11 @@
 
 // +build go1.11
 
-// Package godrop provides a simple privileges dropping library
+// Package godrop provides a simple library to drop privileges on Linux and OpenBSD.
 package godrop
 
 import (
+	"errors"
 	"fmt"
 	"net"
 	"os"
@@ -14,10 +15,6 @@ import (
 	"syscall"
 )
 
-func errf(i interface{}) error {
-	return fmt.Errorf("godrop: %s", i)
-}
-
 // Config represents the drop config
 type Config struct {
 	// User is the user to drop privileges to.
@@ -43,21 +40,21 @@ func Drop(c Config, f func() (net.Listener, error)) error {
 func MultiDrop(c Config, f func() ([]net.Listener, error)) error {
 	uid, err := userID(c.User)
 	if err != nil {
-		return errf(err)
+		return errors.New("godrop: " + err.Error())
 	}
 	if uid == 0 {
-		return errf("unable to drop privileges to uid 0 (root)")
+		return fmt.Errorf("godrop: you can't drop privileges to uid 0 (%s)", c.User)
 	}
 	gid, err := groupID(c.Group)
 	if err != nil {
-		return errf(err)
+		return errors.New("godrop: " + err.Error())
 	}
 	switch os.Getuid() {
 	case 0:
 		cmd := exec.Command(os.Args[0], os.Args[1:]...)
 		ln, err := f()
 		if err != nil {
-			return errf(err)
+			return errors.New("godrop: " + err.Error())
 		}
 		for i, v := range ln {
 			var f *os.File
@@ -69,10 +66,10 @@ func MultiDrop(c Config, f func() ([]net.Listener, error)) error {
 				f, err = l.File()
 				l.Close()
 			default:
-				return errf(fmt.Sprintf("index %d listener is not type of either *net.TCPListener or *net.UnixListener", i))
+				return fmt.Errorf("godrop: index %d listener is not type of either *net.TCPListener or *net.UnixListener", i)
 			}
 			if err != nil {
-				return errf(fmt.Sprintf("index %d %s", i, err))
+				return fmt.Errorf("godrop: index %d %s", i, err)
 			}
 			cmd.ExtraFiles = append(cmd.ExtraFiles, f)
 		}
@@ -93,7 +90,7 @@ func MultiDrop(c Config, f func() ([]net.Listener, error)) error {
 		}
 
 		if err := cmd.Start(); err != nil {
-			return errf(err)
+			return errors.New("godrop: " + err.Error())
 		}
 
 		if c.Foreground {
@@ -120,7 +117,7 @@ func MultiDrop(c Config, f func() ([]net.Listener, error)) error {
 	case uid:
 		return nil
 	}
-	return errf("dropping priviledges failed")
+	return errors.New("godrop: dropping priviledges failed")
 }
 
 // GetListener returns the listener socket of file descriptor 3
@@ -131,7 +128,7 @@ func GetListener() (net.Listener, error) {
 // GetListenerFd returns the listener socket of the given file descriptor
 func GetListenerFd(fd int) (net.Listener, error) {
 	if fd < 3 {
-		return nil, errf("fd is less than 3")
+		return nil, errors.New("godrop: fd is less than 3")
 	}
 	f := os.NewFile(uintptr(fd), "")
 	defer f.Close()

pledge.go

@@ -0,0 +1,14 @@
+// Copyright (C) 2018 Marius Schellenberger
+
+// +build !openbsd
+
+package godrop
+
+// Pledge is currently only supported on OpenBSD.
+func Pledge(promises, execpromises string) error { return nil }
+
+// PledgePromises is currently only supported on OpenBSD.
+func PledgePromises(promises string) error { return nil }
+
+// PledgeExecPromises is currently only supported on OpenBSD.
+func PledgeExecpromises(execpromises string) error { return nil }

pledge_openbsd.go

@@ -0,0 +1,43 @@
+// Copyright (C) 2018 Marius Schellenberger
+
+// +build openbsd
+
+package godrop
+
+import (
+	"errors"
+	"golang.org/x/sys/unix"
+)
+
+// Pledge is a wrapper for x/sys/unix Pledge.
+//
+// See https://go.googlesource.com/sys/+/master/unix/openbsd_pledge.go for usage.
+func Pledge(promises, execpromises string) (err error) {
+	err = unix.Pledge(promises, execpromises)
+	if err != nil {
+		err = errors.New("pledge: " + err.Error())
+	}
+	return
+}
+
+// PledgePromises is a wrapper for x/sys/unix PledgePromises.
+//
+// See https://go.googlesource.com/sys/+/master/unix/openbsd_pledge.go for usage.
+func PledgePromises(promises string) (err error) {
+	err = unix.PledgePromises(promises)
+	if err != nil {
+		err = errors.New("pledge: " + err.Error())
+	}
+	return
+}
+
+// PledgeExecpromises is a wrapper for x/sys/unix PledgeExecpromises.
+//
+// See https://go.googlesource.com/sys/+/master/unix/openbsd_pledge.go for usage.
+func PledgeExecpromises(execpromises string) (err error) {
+	err = unix.PledgeExecpromises(execpromises)
+	if err != nil {
+		err = errors.New("pledge: " + err.Error())
+	}
+	return
+}

unveil.go

@@ -0,0 +1,11 @@
+// Copyright (C) 2018 Marius Schellenberger
+
+// +build !openbsd
+
+package godrop
+
+// Unveil is currently only supported on OpenBSD.
+func Unveil(path, flags string) error { return nil }
+
+// UnveilBlock is currently only supported on OpenBSD.
+func UnveilBlock() error { return nil }

unveil_openbsd.go

@@ -0,0 +1,32 @@
+// Copyright (C) 2018 Marius Schellenberger
+
+// +build openbsd
+
+package godrop
+
+import (
+	"errors"
+	"golang.org/x/sys/unix"
+)
+
+// Unveil is a wrapper for x/sys/unix Unveil.
+//
+// See https://go.googlesource.com/sys/+/master/unix/openbsd_unveil.go for usage.
+func Unveil(path, flags string) (err error) {
+	err = unix.Unveil(path, flags)
+	if err != nil {
+		err = errors.New("unveil: ", err.Error())
+	}
+	return
+}
+
+// UnveilBlock is a wrapper for x/sys/unix UnveilBlock.
+//
+// See https://go.googlesource.com/sys/+/master/unix/openbsd_unveil.go for usage.
+func UnveilBlock() (err error) {
+	err = unix.UnveilBlock()
+	if err != nil {
+		err = errors.New("unveil: ", err.Error())
+	}
+	return
+}