mirror of
https://github.com/tailscale/tailscale.git
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0410f1a35a
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
73 lines
1.5 KiB
Go
73 lines
1.5 KiB
Go
// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build (!cgo || osusergo) && (linux || darwin)
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// +build !cgo osusergo
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// +build linux darwin
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package groupmember
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import (
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"bufio"
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"fmt"
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"os"
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"os/exec"
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"strings"
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"go4.org/mem"
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"tailscale.com/version/distro"
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)
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func isMemberOfGroup(group, name string) (bool, error) {
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if distro.Get() == distro.Synology {
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return isMemberOfGroupEtcGroup(group, name)
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}
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cmd := exec.Command("/usr/bin/env", "groups", name)
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out, err := cmd.CombinedOutput()
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if err != nil {
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return false, err
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}
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groups := strings.Split(strings.TrimSpace(string(out)), " ")
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for _, g := range groups {
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if g == group {
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return true, nil
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}
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}
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return false, nil
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}
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func isMemberOfGroupEtcGroup(group, name string) (bool, error) {
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f, err := os.Open("/etc/group")
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if err != nil {
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return false, err
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}
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defer f.Close()
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s := bufio.NewScanner(f)
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var agLine string
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for s.Scan() {
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if !mem.HasPrefix(mem.B(s.Bytes()), mem.S(fmt.Sprintf("%s:", group))) {
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continue
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}
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agLine = s.Text()
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break
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}
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if err := s.Err(); err != nil {
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return false, err
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}
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if agLine == "" {
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return false, fmt.Errorf("admin group not defined")
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}
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agEntry := strings.Split(agLine, ":")
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if len(agEntry) < 4 {
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return false, fmt.Errorf("malformed admin group entry")
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}
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agMembers := agEntry[3]
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for _, m := range strings.Split(agMembers, ",") {
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if m == name {
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return true, nil
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}
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}
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return false, nil
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}
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