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// Copyright 2021 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package asymkey
import (
"bufio"
"context"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"sync"
"time"
"code.gitea.io/gitea/models/db"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/setting"
"code.gitea.io/gitea/modules/util"
)
// _____ __ .__ .__ .___
// / _ \ __ ___/ |_| |__ ___________|__|_______ ____ __| _/
// / /_\ \| | \ __\ | \ / _ \_ __ \ \___ // __ \ / __ |
// / | \ | /| | | Y ( <_> ) | \/ |/ /\ ___// /_/ |
// \____|__ /____/ |__| |___| /\____/|__| |__/_____ \\___ >____ |
// \/ \/ \/ \/ \/
// ____ __.
// | |/ _|____ ___.__. ______
// | <_/ __ < | |/ ___/
// | | \ ___/\___ |\___ \
// |____|__ \___ > ____/____ >
// \/ \/\/ \/
//
// This file contains functions for creating authorized_keys files
//
// There is a dependence on the database within RegeneratePublicKeys however most of these functions probably belong in a module
const (
tplCommentPrefix = `# gitea public key`
tplPublicKey = tplCommentPrefix + "\n" + `command=%s,no-port-forwarding,no-X11-forwarding,no-agent-forwarding,no-pty,no-user-rc,restrict %s` + "\n"
)
var sshOpLocker sync.Mutex
// AuthorizedStringForKey creates the authorized keys string appropriate for the provided key
func AuthorizedStringForKey(key *PublicKey) string {
sb := &strings.Builder{}
_ = setting.SSH.AuthorizedKeysCommandTemplateTemplate.Execute(sb, map[string]any{
"AppPath": util.ShellEscape(setting.AppPath),
"AppWorkPath": util.ShellEscape(setting.AppWorkPath),
"CustomConf": util.ShellEscape(setting.CustomConf),
"CustomPath": util.ShellEscape(setting.CustomPath),
"Key": key,
})
return fmt.Sprintf(tplPublicKey, util.ShellEscape(sb.String()), key.Content)
}
// appendAuthorizedKeysToFile appends new SSH keys' content to authorized_keys file.
func appendAuthorizedKeysToFile(keys ...*PublicKey) error {
// Don't need to rewrite this file if builtin SSH server is enabled.
if setting.SSH.StartBuiltinServer || !setting.SSH.CreateAuthorizedKeysFile {
return nil
}
sshOpLocker.Lock()
defer sshOpLocker.Unlock()
if setting.SSH.RootPath != "" {
// First of ensure that the RootPath is present, and if not make it with 0700 permissions
// This of course doesn't guarantee that this is the right directory for authorized_keys
// but at least if it's supposed to be this directory and it doesn't exist and we're the
// right user it will at least be created properly.
err := os.MkdirAll(setting.SSH.RootPath, 0o700)
if err != nil {
log.Error("Unable to MkdirAll(%s): %v", setting.SSH.RootPath, err)
return err
}
}
fPath := filepath.Join(setting.SSH.RootPath, "authorized_keys")
f, err := os.OpenFile(fPath, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0o600)
if err != nil {
return err
}
defer f.Close()
// Note: chmod command does not support in Windows.
if !setting.IsWindows {
fi, err := f.Stat()
if err != nil {
return err
}
// .ssh directory should have mode 700, and authorized_keys file should have mode 600.
if fi.Mode().Perm() > 0o600 {
log.Error("authorized_keys file has unusual permission flags: %s - setting to -rw-------", fi.Mode().Perm().String())
if err = f.Chmod(0o600); err != nil {
return err
}
}
}
for _, key := range keys {
if key.Type == KeyTypePrincipal {
continue
}
if _, err = f.WriteString(key.AuthorizedString()); err != nil {
return err
}
}
return nil
}
// RewriteAllPublicKeys removes any authorized key and rewrite all keys from database again.
// Note: db.GetEngine(ctx).Iterate does not get latest data after insert/delete, so we have to call this function
// outside any session scope independently.
func RewriteAllPublicKeys(ctx context.Context) error {
// Don't rewrite key if internal server
if setting.SSH.StartBuiltinServer || !setting.SSH.CreateAuthorizedKeysFile {
return nil
}
sshOpLocker.Lock()
defer sshOpLocker.Unlock()
if setting.SSH.RootPath != "" {
// First of ensure that the RootPath is present, and if not make it with 0700 permissions
// This of course doesn't guarantee that this is the right directory for authorized_keys
// but at least if it's supposed to be this directory and it doesn't exist and we're the
// right user it will at least be created properly.
err := os.MkdirAll(setting.SSH.RootPath, 0o700)
if err != nil {
log.Error("Unable to MkdirAll(%s): %v", setting.SSH.RootPath, err)
return err
}
}
fPath := filepath.Join(setting.SSH.RootPath, "authorized_keys")
tmpPath := fPath + ".tmp"
t, err := os.OpenFile(tmpPath, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0o600)
if err != nil {
return err
}
defer func() {
t.Close()
if err := util.Remove(tmpPath); err != nil {
log.Warn("Unable to remove temporary authorized keys file: %s: Error: %v", tmpPath, err)
}
}()
if setting.SSH.AuthorizedKeysBackup {
isExist, err := util.IsExist(fPath)
if err != nil {
log.Error("Unable to check if %s exists. Error: %v", fPath, err)
return err
}
if isExist {
bakPath := fmt.Sprintf("%s_%d.gitea_bak", fPath, time.Now().Unix())
if err = util.CopyFile(fPath, bakPath); err != nil {
return err
}
}
}
if err := RegeneratePublicKeys(ctx, t); err != nil {
return err
}
if err := t.Sync(); err != nil {
return err
}
if err := t.Close(); err != nil {
return err
}
return util.Rename(tmpPath, fPath)
}
// RegeneratePublicKeys regenerates the authorized_keys file
func RegeneratePublicKeys(ctx context.Context, t io.StringWriter) error {
if err := db.GetEngine(ctx).Where("type != ?", KeyTypePrincipal).Iterate(new(PublicKey), func(idx int, bean any) (err error) {
_, err = t.WriteString((bean.(*PublicKey)).AuthorizedString())
return err
}); err != nil {
return err
}
fPath := filepath.Join(setting.SSH.RootPath, "authorized_keys")
isExist, err := util.IsExist(fPath)
if err != nil {
log.Error("Unable to check if %s exists. Error: %v", fPath, err)
return err
}
if isExist {
f, err := os.Open(fPath)
if err != nil {
return err
}
defer f.Close()
scanner := bufio.NewScanner(f)
for scanner.Scan() {
line := scanner.Text()
if strings.HasPrefix(line, tplCommentPrefix) {
scanner.Scan()
continue
}
_, err = t.WriteString(line + "\n")
if err != nil {
return err
}
}
if err = scanner.Err(); err != nil {
return fmt.Errorf("RegeneratePublicKeys scan: %w", err)
}
}
return nil
}
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