forgejo/models/asymkey/ssh_key_authorized_keys.go
Gusted cf8b64f937
[GITEA] Make atomic ssh keys replacement robust
- After stumbling upon https://github.com/golang/go/issues/22397 and
reading the implementations I realized that Forgejo code doesn't have
`Sync()` and it doesn't properly error handle the `Close` function.
- (likely) Resolves https://codeberg.org/forgejo/forgejo/issues/1446

(cherry picked from commit 0efcb334c2)
(cherry picked from commit 04ef02c0dd)
(cherry picked from commit 85f2065c9b)
(cherry picked from commit 8d36b5cce6)
(cherry picked from commit 0f406dc4d2)
(cherry picked from commit 347a2e7372)
(cherry picked from commit f6c04d6b86)
2023-11-06 17:12:22 +01:00

217 lines
6.4 KiB
Go

// 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(db.DefaultContext).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
}
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 {
f.Close()
return err
}
}
f.Close()
}
return nil
}