mirror of
https://github.com/versity/versitygw.git
synced 2026-09-27 02:14:15 +00:00
Ben McClelland
c26012905c
A concurrent PutObject and DeleteObject on the same prefix directory can race: PutObject opens an O_TMPFILE in MetaTmpDir (not yet visible in the fs) DeleteObject removes the last visible object in the prefix directory and calls removeParents(), which rmdir's the now-empty prefix directory PutObject's link() tries to link the fd into a parent directory that no longer exists Fix by detecting ENOENT in the final link step (Linkat, Rename, and MoveFile) and retrying after recreating the parent directory. Also extract linkatOTmpfile() to consolidate the Linkat+EEXIST→Renameat logic that was previously inline in link(). Fixes #1988
133 lines
3.1 KiB
Go
133 lines
3.1 KiB
Go
// Copyright 2023 Versity Software
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// This file is licensed under the Apache License, Version 2.0
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// (the "License"); you may not use this file except in compliance
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// with the License. You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing,
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// software distributed under the License is distributed on an
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// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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// KIND, either express or implied. See the License for the
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// specific language governing permissions and limitations
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// under the License.
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//go:build !linux
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package posix
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import (
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"crypto/sha256"
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"errors"
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"fmt"
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"io/fs"
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"os"
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"path/filepath"
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"syscall"
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"github.com/versity/versitygw/auth"
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"github.com/versity/versitygw/backend"
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"github.com/versity/versitygw/s3err"
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)
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const (
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initialBackoffMs = 1
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maxBackoffMs = 1024 // ~1 second
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)
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type tmpfile struct {
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f *os.File
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bucket string
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objname string
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size int64
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newDirPerm fs.FileMode
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uid int
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gid int
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doChown bool
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}
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func (p *Posix) openTmpFile(dir, bucket, obj string, size int64, acct auth.Account, _ bool, _ bool) (*tmpfile, error) {
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uid, gid, doChown := p.getChownIDs(acct)
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// Create a temp file for upload while in progress (see link comments below).
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var err error
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err = backend.MkdirAll(dir, uid, gid, doChown, p.newDirPerm)
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if err != nil {
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if errors.Is(err, syscall.EROFS) {
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return nil, s3err.GetAPIError(s3err.ErrMethodNotAllowed)
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}
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return nil, fmt.Errorf("make temp dir: %w", err)
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}
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f, err := os.CreateTemp(dir,
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fmt.Sprintf("%x.", sha256.Sum256([]byte(obj))))
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if err != nil {
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if errors.Is(err, syscall.EROFS) {
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return nil, s3err.GetAPIError(s3err.ErrMethodNotAllowed)
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}
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return nil, fmt.Errorf("create temp file: %w", err)
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}
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if doChown {
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err := f.Chown(uid, gid)
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if err != nil {
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f.Close()
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os.Remove(f.Name())
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return nil, fmt.Errorf("set temp file ownership: %w", err)
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}
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}
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return &tmpfile{
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f: f,
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bucket: bucket,
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objname: obj,
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size: size,
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newDirPerm: p.newDirPerm,
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uid: uid,
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gid: gid,
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doChown: doChown,
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}, nil
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}
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var (
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// TODO: make this configurable
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defaultFilePerm fs.FileMode = 0644
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)
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func (tmp *tmpfile) link() error {
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tempname := tmp.f.Name()
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objPath := filepath.Join(tmp.bucket, tmp.objname)
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// reset default file mode because CreateTemp uses 0600
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tmp.f.Chmod(defaultFilePerm)
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err := tmp.f.Close()
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if err != nil {
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return fmt.Errorf("close tmpfile: %w", err)
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}
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backoffMs := initialBackoffMs
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for {
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err = backend.MoveFile(tempname, objPath, defaultFilePerm)
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if !errors.Is(err, syscall.ENOENT) {
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break
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}
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// The parent directory may have been concurrently removed; backoff and retry.
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// Add jitter to avoid synchronized retry waves.
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sleepWithJitter(backoffMs)
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backoffMs = min((backoffMs * 2), maxBackoffMs)
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err = backend.MkdirAll(filepath.Dir(objPath), tmp.uid, tmp.gid,
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tmp.doChown, tmp.newDirPerm)
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if err != nil {
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return fmt.Errorf("recreate parent dir: %w", err)
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}
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}
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return err
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}
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func (tmp *tmpfile) cleanup() {
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tmp.f.Close()
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os.Remove(tmp.f.Name())
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}
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