55 lines
1.4 KiB
Go
55 lines
1.4 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package osuser
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import (
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"context"
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"fmt"
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"os/exec"
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"os/user"
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"runtime"
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"strings"
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"time"
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"tailscale.com/version/distro"
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)
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// GetGroupIds returns the list of group IDs that the user is a member of, or
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// an error. It will first try to use the 'id' command to get the group IDs,
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// and if that fails, it will fall back to the user.GroupIds method.
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func GetGroupIds(user *user.User) ([]string, error) {
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if runtime.GOOS != "linux" {
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return user.GroupIds()
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}
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if distro.Get() == distro.Gokrazy {
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// Gokrazy is a single-user appliance with ~no userspace.
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// There aren't users to look up (no /etc/passwd, etc)
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// so rather than fail below, just hardcode root.
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// TODO(bradfitz): fix os/user upstream instead?
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return []string{"0"}, nil
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}
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if ids, err := getGroupIdsWithId(user.Username); err == nil {
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return ids, nil
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}
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return user.GroupIds()
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}
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func getGroupIdsWithId(usernameOrUID string) ([]string, error) {
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ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
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defer cancel()
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cmd := exec.CommandContext(ctx, "id", "-Gz", usernameOrUID)
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out, err := cmd.Output()
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if err != nil {
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return nil, fmt.Errorf("running 'id' command: %w", err)
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}
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return parseGroupIds(out), nil
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}
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func parseGroupIds(cmdOutput []byte) []string {
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return strings.Split(strings.Trim(string(cmdOutput), "\n\x00"), "\x00")
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}
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