fix: SFTP HomeDir path translation for user operations (#7611)

* fix: SFTP HomeDir path translation for user operations

When users have a non-root HomeDir (e.g., '/sftp/user'), their SFTP
operations should be relative to that directory. Previously, when a
user uploaded to '/' via SFTP, the path was not translated to their
home directory, causing 'permission denied for / for permission write'.

This fix adds a toAbsolutePath() method that implements chroot-like
behavior where the user's HomeDir becomes their root. All file and
directory operations now translate paths through this method.

Example: User with HomeDir='/sftp/user' uploading to '/' now correctly
maps to '/sftp/user'.

Fixes: https://github.com/seaweedfs/seaweedfs/issues/7470

* test: add SFTP integration tests

Add comprehensive integration tests for the SFTP server including:
- HomeDir path translation tests (verifies fix for issue #7470)
- Basic file upload/download operations
- Directory operations (mkdir, rmdir, list)
- Large file handling (1MB test)
- File rename operations
- Stat/Lstat operations
- Path edge cases (trailing slashes, .., unicode filenames)
- Admin root access verification

The test framework starts a complete SeaweedFS cluster with:
- Master server
- Volume server
- Filer server
- SFTP server with test user credentials

Test users are configured in testdata/userstore.json:
- admin: HomeDir=/ with full access
- testuser: HomeDir=/sftp/testuser with access to home
- readonly: HomeDir=/public with read-only access

* fix: correct SFTP HomeDir path translation and add CI

Fix path.Join issue where paths starting with '/' weren't joined correctly.
path.Join('/sftp/user', '/file') returns '/file' instead of '/sftp/user/file'.
Now we strip the leading '/' before joining.

Test improvements:
- Update go.mod to Go 1.24
- Fix weed binary discovery to prefer local build over PATH
- Add stabilization delay after service startup
- All 8 SFTP integration tests pass locally

Add GitHub Actions workflow for SFTP tests:
- Runs on push/PR affecting sftpd code or tests
- Tests HomeDir path translation, file ops, directory ops
- Covers issue #7470 fix verification

* security: update golang.org/x/crypto to v0.45.0

Addresses security vulnerability in golang.org/x/crypto < 0.45.0

* security: use proper SSH host key verification in tests

Replace ssh.InsecureIgnoreHostKey() with ssh.FixedHostKey() that
verifies the server's host key matches the known test key we generated.
This addresses CodeQL warning go/insecure-hostkeycallback.

Also updates go.mod to specify go 1.24.0 explicitly.

* security: fix path traversal vulnerability in SFTP toAbsolutePath

The previous implementation had a critical security vulnerability:
- Path traversal via '../..' could escape the HomeDir chroot jail
- Absolute paths were not correctly prefixed with HomeDir

The fix:
1. Concatenate HomeDir with userPath directly, then clean
2. Add security check to ensure final path stays within HomeDir
3. If traversal detected, safely return HomeDir instead

Also adds path traversal prevention tests to verify the fix.

* fix: address PR review comments

1. Fix SkipCleanup check to use actual test config instead of default
   - Added skipCleanup field to SftpTestFramework struct
   - Store config.SkipCleanup during Setup()
   - Use f.skipCleanup in Cleanup() instead of DefaultTestConfig()

2. Fix path prefix check false positive in mkdir
   - Changed from strings.HasPrefix(absPath, fs.user.HomeDir)
   - To: absPath == fs.user.HomeDir || strings.HasPrefix(absPath, fs.user.HomeDir+"/")
   - Prevents matching partial directory names (e.g., /sftp/username when HomeDir is /sftp/user)

* fix: check write permission on parent dir for mkdir

Aligns makeDir's permission check with newFileWriter for consistency.
To create a directory, a user needs write permission on the parent
directory, not mkdir permission on the new directory path.

* fix: refine SFTP path traversal logic and tests

1. Refine toAbsolutePath:
   - Use path.Join with strings.TrimPrefix for idiomatic path construction
   - Return explicit error on path traversal attempt instead of clamping
   - Updated all call sites to handle the error

2. Add Unit Tests:
   - Added sftp_server_test.go to verify toAbsolutePath logic
   - Covers normal paths, root path, and various traversal attempts

3. Update Integration Tests:
   - Updated PathTraversalPrevention test to reflect that standard SFTP clients
     sanitize paths before sending. The test now verifies successful containment
     within the jail rather than blocking (since the server receives a clean path).
   - The server-side blocking is verified by the new unit tests.

4. Makefile:
   - Removed -v from default test target

* fix: address PR comments on tests and makefile

1. Enhanced Unit Tests:
   - Added edge cases (empty path, multiple slashes, trailing slash) to sftp_server_test.go

2. Makefile Improvements:
   - Added 'all' target as default entry point

3. Code Clarity:
   - Added comment to mkdir permission check explaining defensive nature of HomeDir check

* fix: address PR review comments on permissions and tests

1. Security:
   - Added write permission check on target directory in renameEntry

2. Logging:
   - Changed dispatch log verbosity from V(0) to V(1)

3. Testing:
   - Updated Makefile .PHONY targets
   - Added unit test cases for empty/root HomeDir behavior in toAbsolutePath

* fix: set SFTP starting directory to virtual root

1. Critical Fix:
   - Changed sftp.WithStartDirectory from fs.user.HomeDir to '/'
   - Prevents double-prefixing when toAbsolutePath translates paths
   - Users now correctly start at their virtual root which maps to HomeDir

2. Test Improvements:
   - Use pointer for homeDir in tests for clearer nil vs empty distinction

* fix: clean HomeDir at config load time

Clean HomeDir path when loading users from JSON config.
This handles trailing slashes and other path anomalies at the source,
ensuring consistency throughout the codebase and avoiding repeated
cleaning on every toAbsolutePath call.

* test: strengthen assertions and add error checking in SFTP tests

1. Add error checking for cleanup operations in TestWalk
2. Strengthen cwd assertion to expect '/' explicitly in TestCurrentWorkingDirectory
3. Add error checking for cleanup in PathTraversalPrevention test

.github/workflows/sftp-tests.yml

@@ -0,0 +1,92 @@
+name: "SFTP Integration Tests"
+
+on:
+  push:
+    branches: [ master, main ]
+    paths:
+      - 'weed/sftpd/**'
+      - 'weed/command/sftp.go'
+      - 'test/sftp/**'
+      - '.github/workflows/sftp-tests.yml'
+  pull_request:
+    branches: [ master, main ]
+    paths:
+      - 'weed/sftpd/**'
+      - 'weed/command/sftp.go'
+      - 'test/sftp/**'
+      - '.github/workflows/sftp-tests.yml'
+
+concurrency:
+  group: ${{ github.head_ref }}/sftp-tests
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+env:
+  GO_VERSION: '1.24'
+  TEST_TIMEOUT: '15m'
+
+jobs:
+  sftp-integration:
+    name: SFTP Integration Testing
+    runs-on: ubuntu-22.04
+    timeout-minutes: 20
+    
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+      
+    - name: Set up Go ${{ env.GO_VERSION }}
+      uses: actions/setup-go@v5
+      with:
+        go-version: ${{ env.GO_VERSION }}
+        
+    - name: Install dependencies
+      run: |
+        sudo apt-get update
+        sudo apt-get install -y openssh-client
+        
+    - name: Build SeaweedFS
+      run: |
+        cd weed
+        go build -o weed .
+        chmod +x weed
+        ./weed version
+        
+    - name: Run SFTP Integration Tests
+      run: |
+        cd test/sftp
+        
+        echo "🧪 Running SFTP integration tests..."
+        echo "============================================"
+        
+        # Install test dependencies
+        go mod download
+        
+        # Run all SFTP tests
+        go test -v -timeout=${{ env.TEST_TIMEOUT }} ./...
+        
+        echo "============================================"
+        echo "✅ SFTP integration tests completed"
+        
+    - name: Test Summary
+      if: always()
+      run: |
+        echo "## 🔐 SFTP Integration Test Summary" >> $GITHUB_STEP_SUMMARY
+        echo "" >> $GITHUB_STEP_SUMMARY
+        echo "### Test Coverage" >> $GITHUB_STEP_SUMMARY
+        echo "- ✅ **HomeDir Path Translation**: User home directory mapping (fixes #7470)" >> $GITHUB_STEP_SUMMARY
+        echo "- ✅ **File Operations**: Upload, download, delete" >> $GITHUB_STEP_SUMMARY
+        echo "- ✅ **Directory Operations**: Create, list, remove" >> $GITHUB_STEP_SUMMARY
+        echo "- ✅ **Large File Handling**: 1MB+ file support" >> $GITHUB_STEP_SUMMARY
+        echo "- ✅ **Path Edge Cases**: Unicode, trailing slashes, .. paths" >> $GITHUB_STEP_SUMMARY
+        echo "- ✅ **Admin Access**: Root user verification" >> $GITHUB_STEP_SUMMARY
+        echo "" >> $GITHUB_STEP_SUMMARY
+        echo "### Test Configuration" >> $GITHUB_STEP_SUMMARY
+        echo "| User | HomeDir | Permissions |" >> $GITHUB_STEP_SUMMARY
+        echo "|------|---------|-------------|" >> $GITHUB_STEP_SUMMARY
+        echo "| admin | / | Full access |" >> $GITHUB_STEP_SUMMARY
+        echo "| testuser | /sftp/testuser | Home directory only |" >> $GITHUB_STEP_SUMMARY
+        echo "| readonly | /public | Read-only |" >> $GITHUB_STEP_SUMMARY
+

test/sftp/Makefile

@@ -0,0 +1,41 @@
+.PHONY: all build test test-verbose test-short test-homedir test-debug clean deps tidy
+
+all: build test
+
+# Build the weed binary first
+build:
+	cd ../../weed && go build -o weed .
+
+# Install test dependencies
+deps:
+	go mod download
+
+# Run all tests
+test: build deps
+	go test -timeout 5m ./...
+
+# Run tests with verbose output
+test-verbose: build deps
+	go test -v -timeout 5m ./...
+
+# Run quick tests only (skip integration tests)
+test-short: deps
+	go test -short -v ./...
+
+# Run specific test
+test-homedir: build deps
+	go test -v -timeout 5m -run TestHomeDirPathTranslation ./...
+
+# Run tests with debug output from SeaweedFS
+test-debug: build deps
+	go test -v -timeout 5m ./... 2>&1 | tee test.log
+
+# Clean up test artifacts
+clean:
+	rm -f test.log
+	go clean -testcache
+
+# Update go.sum
+tidy:
+	go mod tidy
+

test/sftp/README.md

@@ -0,0 +1,91 @@
+# SeaweedFS SFTP Integration Tests
+
+This directory contains integration tests for the SeaweedFS SFTP server.
+
+## Prerequisites
+
+1. Build the SeaweedFS binary:
+   ```bash
+   cd ../../weed
+   go build -o weed .
+   ```
+
+2. Ensure `ssh-keygen` is available (for generating test SSH host keys)
+
+## Running Tests
+
+### Run all tests
+```bash
+make test
+```
+
+### Run tests with verbose output
+```bash
+make test-verbose
+```
+
+### Run a specific test
+```bash
+go test -v -run TestHomeDirPathTranslation
+```
+
+### Skip long-running tests
+```bash
+go test -short ./...
+```
+
+## Test Structure
+
+- `framework.go` - Test framework that starts SeaweedFS cluster with SFTP
+- `basic_test.go` - Basic SFTP operation tests including:
+  - HomeDir path translation (fixes issue #7470)
+  - File upload/download
+  - Directory operations
+  - Large file handling
+  - Edge cases
+
+## Test Configuration
+
+Tests use `testdata/userstore.json` which defines test users:
+
+| Username | Password | HomeDir | Permissions |
+|----------|----------|---------|-------------|
+| admin | adminpassword | / | Full access |
+| testuser | testuserpassword | /sftp/testuser | Full access to home |
+| readonly | readonlypassword | /public | Read-only |
+
+## Key Tests
+
+### TestHomeDirPathTranslation
+
+Tests the fix for [issue #7470](https://github.com/seaweedfs/seaweedfs/issues/7470) where
+users with a non-root HomeDir (e.g., `/sftp/testuser`) could not upload files to `/`
+because the path wasn't being translated to their home directory.
+
+The test verifies:
+- Uploading to `/` correctly maps to the user's HomeDir
+- Creating directories at `/` works
+- Listing `/` shows the user's home directory contents
+- All path operations respect the HomeDir translation
+
+## Debugging
+
+To debug test failures:
+
+1. Enable verbose output:
+   ```bash
+   go test -v -run TestName
+   ```
+
+2. Keep test artifacts (don't cleanup):
+   ```go
+   config := DefaultTestConfig()
+   config.SkipCleanup = true
+   ```
+
+3. Enable debug logging:
+   ```go
+   config := DefaultTestConfig()
+   config.EnableDebug = true
+   ```
+

test/sftp/basic_test.go

@@ -0,0 +1,652 @@
+package sftp
+
+import (
+	"bytes"
+	"io"
+	"path"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+// TestHomeDirPathTranslation tests that SFTP operations correctly translate
+// paths relative to the user's HomeDir.
+// This is the fix for https://github.com/seaweedfs/seaweedfs/issues/7470
+func TestHomeDirPathTranslation(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping integration test in short mode")
+	}
+
+	config := DefaultTestConfig()
+	config.EnableDebug = testing.Verbose()
+
+	fw := NewSftpTestFramework(t, config)
+	err := fw.Setup(config)
+	require.NoError(t, err, "failed to setup test framework")
+	defer fw.Cleanup()
+
+	// Test with user "testuser" who has HomeDir="/sftp/testuser"
+	// When they upload to "/", it should actually go to "/sftp/testuser"
+	sftpClient, sshConn, err := fw.ConnectSFTP("testuser", "testuserpassword")
+	require.NoError(t, err, "failed to connect as testuser")
+	defer sshConn.Close()
+	defer sftpClient.Close()
+
+	// Test 1: Upload file to "/" (should map to /sftp/testuser/)
+	t.Run("UploadToRoot", func(t *testing.T) {
+		testContent := []byte("Hello from SFTP test!")
+		filename := "test_upload.txt"
+
+		// Create file at "/" from user's perspective
+		file, err := sftpClient.Create("/" + filename)
+		require.NoError(t, err, "should be able to create file at /")
+
+		_, err = file.Write(testContent)
+		require.NoError(t, err, "should be able to write to file")
+		err = file.Close()
+		require.NoError(t, err, "should be able to close file")
+
+		// Verify file exists and has correct content
+		readFile, err := sftpClient.Open("/" + filename)
+		require.NoError(t, err, "should be able to open file")
+		defer readFile.Close()
+
+		content, err := io.ReadAll(readFile)
+		require.NoError(t, err, "should be able to read file")
+		require.Equal(t, testContent, content, "file content should match")
+
+		// Clean up
+		err = sftpClient.Remove("/" + filename)
+		require.NoError(t, err, "should be able to remove file")
+	})
+
+	// Test 2: Create directory at "/" (should map to /sftp/testuser/)
+	t.Run("CreateDirAtRoot", func(t *testing.T) {
+		dirname := "test_dir"
+
+		err := sftpClient.Mkdir("/" + dirname)
+		require.NoError(t, err, "should be able to create directory at /")
+
+		// Verify directory exists
+		info, err := sftpClient.Stat("/" + dirname)
+		require.NoError(t, err, "should be able to stat directory")
+		require.True(t, info.IsDir(), "should be a directory")
+
+		// Clean up
+		err = sftpClient.RemoveDirectory("/" + dirname)
+		require.NoError(t, err, "should be able to remove directory")
+	})
+
+	// Test 3: List directory at "/" (should list /sftp/testuser/)
+	t.Run("ListRoot", func(t *testing.T) {
+		// Create a test file first
+		testContent := []byte("list test content")
+		filename := "list_test.txt"
+
+		file, err := sftpClient.Create("/" + filename)
+		require.NoError(t, err)
+		_, err = file.Write(testContent)
+		require.NoError(t, err)
+		file.Close()
+
+		// List root directory
+		files, err := sftpClient.ReadDir("/")
+		require.NoError(t, err, "should be able to list root directory")
+
+		// Should find our test file
+		found := false
+		for _, f := range files {
+			if f.Name() == filename {
+				found = true
+				break
+			}
+		}
+		require.True(t, found, "should find test file in listing")
+
+		// Clean up
+		err = sftpClient.Remove("/" + filename)
+		require.NoError(t, err)
+	})
+
+	// Test 4: Nested directory operations
+	t.Run("NestedOperations", func(t *testing.T) {
+		// Create nested directory structure
+		err := sftpClient.MkdirAll("/nested/dir/structure")
+		require.NoError(t, err, "should be able to create nested directories")
+
+		// Create file in nested directory
+		testContent := []byte("nested file content")
+		file, err := sftpClient.Create("/nested/dir/structure/file.txt")
+		require.NoError(t, err)
+		_, err = file.Write(testContent)
+		require.NoError(t, err)
+		file.Close()
+
+		// Verify file exists
+		readFile, err := sftpClient.Open("/nested/dir/structure/file.txt")
+		require.NoError(t, err)
+		content, err := io.ReadAll(readFile)
+		require.NoError(t, err)
+		readFile.Close()
+		require.Equal(t, testContent, content)
+
+		// Clean up
+		err = sftpClient.Remove("/nested/dir/structure/file.txt")
+		require.NoError(t, err)
+		err = sftpClient.RemoveDirectory("/nested/dir/structure")
+		require.NoError(t, err)
+		err = sftpClient.RemoveDirectory("/nested/dir")
+		require.NoError(t, err)
+		err = sftpClient.RemoveDirectory("/nested")
+		require.NoError(t, err)
+	})
+
+	// Test 5: Rename operation
+	t.Run("RenameFile", func(t *testing.T) {
+		testContent := []byte("rename test content")
+
+		file, err := sftpClient.Create("/original.txt")
+		require.NoError(t, err)
+		_, err = file.Write(testContent)
+		require.NoError(t, err)
+		file.Close()
+
+		// Rename file
+		err = sftpClient.Rename("/original.txt", "/renamed.txt")
+		require.NoError(t, err, "should be able to rename file")
+
+		// Verify old file doesn't exist
+		_, err = sftpClient.Stat("/original.txt")
+		require.Error(t, err, "original file should not exist")
+
+		// Verify new file exists with correct content
+		readFile, err := sftpClient.Open("/renamed.txt")
+		require.NoError(t, err, "renamed file should exist")
+		content, err := io.ReadAll(readFile)
+		require.NoError(t, err)
+		readFile.Close()
+		require.Equal(t, testContent, content)
+
+		// Clean up
+		err = sftpClient.Remove("/renamed.txt")
+		require.NoError(t, err)
+	})
+}
+
+// TestAdminRootAccess tests that admin user with HomeDir="/" can access everything
+func TestAdminRootAccess(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping integration test in short mode")
+	}
+
+	config := DefaultTestConfig()
+	config.EnableDebug = testing.Verbose()
+
+	fw := NewSftpTestFramework(t, config)
+	err := fw.Setup(config)
+	require.NoError(t, err, "failed to setup test framework")
+	defer fw.Cleanup()
+
+	// Connect as admin with HomeDir="/"
+	sftpClient, sshConn, err := fw.ConnectSFTP("admin", "adminpassword")
+	require.NoError(t, err, "failed to connect as admin")
+	defer sshConn.Close()
+	defer sftpClient.Close()
+
+	// Admin should be able to create directories anywhere
+	t.Run("CreateAnyDirectory", func(t *testing.T) {
+		// Create the user's home directory structure
+		err := sftpClient.MkdirAll("/sftp/testuser")
+		require.NoError(t, err, "admin should be able to create any directory")
+
+		// Create file in that directory
+		testContent := []byte("admin created this")
+		file, err := sftpClient.Create("/sftp/testuser/admin_file.txt")
+		require.NoError(t, err)
+		_, err = file.Write(testContent)
+		require.NoError(t, err)
+		file.Close()
+
+		// Verify file exists
+		info, err := sftpClient.Stat("/sftp/testuser/admin_file.txt")
+		require.NoError(t, err)
+		require.False(t, info.IsDir())
+
+		// Clean up
+		err = sftpClient.Remove("/sftp/testuser/admin_file.txt")
+		require.NoError(t, err)
+	})
+}
+
+// TestLargeFileUpload tests uploading larger files through SFTP
+func TestLargeFileUpload(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping integration test in short mode")
+	}
+
+	config := DefaultTestConfig()
+	config.EnableDebug = testing.Verbose()
+
+	fw := NewSftpTestFramework(t, config)
+	err := fw.Setup(config)
+	require.NoError(t, err, "failed to setup test framework")
+	defer fw.Cleanup()
+
+	sftpClient, sshConn, err := fw.ConnectSFTP("testuser", "testuserpassword")
+	require.NoError(t, err, "failed to connect as testuser")
+	defer sshConn.Close()
+	defer sftpClient.Close()
+
+	// Create a 1MB file
+	t.Run("Upload1MB", func(t *testing.T) {
+		size := 1024 * 1024 // 1MB
+		testData := bytes.Repeat([]byte("A"), size)
+
+		file, err := sftpClient.Create("/large_file.bin")
+		require.NoError(t, err)
+		n, err := file.Write(testData)
+		require.NoError(t, err)
+		require.Equal(t, size, n)
+		file.Close()
+
+		// Verify file size
+		info, err := sftpClient.Stat("/large_file.bin")
+		require.NoError(t, err)
+		require.Equal(t, int64(size), info.Size())
+
+		// Verify content
+		readFile, err := sftpClient.Open("/large_file.bin")
+		require.NoError(t, err)
+		content, err := io.ReadAll(readFile)
+		require.NoError(t, err)
+		readFile.Close()
+		require.Equal(t, testData, content)
+
+		// Clean up
+		err = sftpClient.Remove("/large_file.bin")
+		require.NoError(t, err)
+	})
+}
+
+// TestStatOperations tests Stat and Lstat operations
+func TestStatOperations(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping integration test in short mode")
+	}
+
+	config := DefaultTestConfig()
+	config.EnableDebug = testing.Verbose()
+
+	fw := NewSftpTestFramework(t, config)
+	err := fw.Setup(config)
+	require.NoError(t, err, "failed to setup test framework")
+	defer fw.Cleanup()
+
+	sftpClient, sshConn, err := fw.ConnectSFTP("testuser", "testuserpassword")
+	require.NoError(t, err, "failed to connect as testuser")
+	defer sshConn.Close()
+	defer sftpClient.Close()
+
+	// Create a test file
+	testContent := []byte("stat test content")
+	file, err := sftpClient.Create("/stat_test.txt")
+	require.NoError(t, err)
+	_, err = file.Write(testContent)
+	require.NoError(t, err)
+	file.Close()
+
+	t.Run("StatFile", func(t *testing.T) {
+		info, err := sftpClient.Stat("/stat_test.txt")
+		require.NoError(t, err)
+		require.Equal(t, "stat_test.txt", info.Name())
+		require.Equal(t, int64(len(testContent)), info.Size())
+		require.False(t, info.IsDir())
+	})
+
+	t.Run("StatDirectory", func(t *testing.T) {
+		err := sftpClient.Mkdir("/stat_dir")
+		require.NoError(t, err)
+
+		info, err := sftpClient.Stat("/stat_dir")
+		require.NoError(t, err)
+		require.Equal(t, "stat_dir", info.Name())
+		require.True(t, info.IsDir())
+
+		// Clean up
+		err = sftpClient.RemoveDirectory("/stat_dir")
+		require.NoError(t, err)
+	})
+
+	t.Run("StatRoot", func(t *testing.T) {
+		// Should be able to stat "/" which maps to user's home directory
+		info, err := sftpClient.Stat("/")
+		require.NoError(t, err, "should be able to stat root (home) directory")
+		require.True(t, info.IsDir(), "root should be a directory")
+	})
+
+	// Clean up
+	err = sftpClient.Remove("/stat_test.txt")
+	require.NoError(t, err)
+}
+
+// TestWalk tests walking directory trees
+func TestWalk(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping integration test in short mode")
+	}
+
+	config := DefaultTestConfig()
+	config.EnableDebug = testing.Verbose()
+
+	fw := NewSftpTestFramework(t, config)
+	err := fw.Setup(config)
+	require.NoError(t, err, "failed to setup test framework")
+	defer fw.Cleanup()
+
+	sftpClient, sshConn, err := fw.ConnectSFTP("testuser", "testuserpassword")
+	require.NoError(t, err, "failed to connect as testuser")
+	defer sshConn.Close()
+	defer sftpClient.Close()
+
+	// Create directory structure
+	err = sftpClient.MkdirAll("/walk/a/b")
+	require.NoError(t, err)
+	err = sftpClient.MkdirAll("/walk/c")
+	require.NoError(t, err)
+
+	// Create files
+	for _, p := range []string{"/walk/file1.txt", "/walk/a/file2.txt", "/walk/a/b/file3.txt", "/walk/c/file4.txt"} {
+		file, err := sftpClient.Create(p)
+		require.NoError(t, err)
+		file.Write([]byte("test"))
+		file.Close()
+	}
+
+	t.Run("WalkEntireTree", func(t *testing.T) {
+		var paths []string
+		walker := sftpClient.Walk("/walk")
+		for walker.Step() {
+			if walker.Err() != nil {
+				continue
+			}
+			paths = append(paths, walker.Path())
+		}
+
+		// Should find all directories and files
+		require.Contains(t, paths, "/walk")
+		require.Contains(t, paths, "/walk/a")
+		require.Contains(t, paths, "/walk/a/b")
+		require.Contains(t, paths, "/walk/c")
+	})
+
+	// Clean up
+	for _, p := range []string{"/walk/file1.txt", "/walk/a/file2.txt", "/walk/a/b/file3.txt", "/walk/c/file4.txt"} {
+		require.NoError(t, sftpClient.Remove(p))
+	}
+	for _, p := range []string{"/walk/a/b", "/walk/a", "/walk/c", "/walk"} {
+		require.NoError(t, sftpClient.RemoveDirectory(p))
+	}
+}
+
+// TestCurrentWorkingDirectory tests that Getwd and Chdir work correctly
+func TestCurrentWorkingDirectory(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping integration test in short mode")
+	}
+
+	config := DefaultTestConfig()
+	config.EnableDebug = testing.Verbose()
+
+	fw := NewSftpTestFramework(t, config)
+	err := fw.Setup(config)
+	require.NoError(t, err, "failed to setup test framework")
+	defer fw.Cleanup()
+
+	sftpClient, sshConn, err := fw.ConnectSFTP("testuser", "testuserpassword")
+	require.NoError(t, err, "failed to connect as testuser")
+	defer sshConn.Close()
+	defer sftpClient.Close()
+
+	// Create test directory
+	err = sftpClient.Mkdir("/cwd_test")
+	require.NoError(t, err)
+
+	t.Run("GetCurrentDir", func(t *testing.T) {
+		cwd, err := sftpClient.Getwd()
+		require.NoError(t, err)
+		// The initial working directory should be the user's home directory
+		// which from the user's perspective is "/"
+		require.Equal(t, "/", cwd, "initial working directory should be the virtual root")
+	})
+
+	t.Run("ChangeAndCreate", func(t *testing.T) {
+		// Create file in subdirectory using relative path after chdir
+		// Note: pkg/sftp doesn't support Chdir, so we test using absolute paths
+		file, err := sftpClient.Create("/cwd_test/relative_file.txt")
+		require.NoError(t, err)
+		file.Write([]byte("test"))
+		file.Close()
+
+		// Verify using absolute path
+		_, err = sftpClient.Stat("/cwd_test/relative_file.txt")
+		require.NoError(t, err)
+
+		// Clean up
+		sftpClient.Remove("/cwd_test/relative_file.txt")
+	})
+
+	// Clean up
+	err = sftpClient.RemoveDirectory("/cwd_test")
+	require.NoError(t, err)
+}
+
+// TestPathEdgeCases tests various edge cases in path handling
+func TestPathEdgeCases(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping integration test in short mode")
+	}
+
+	config := DefaultTestConfig()
+	config.EnableDebug = testing.Verbose()
+
+	fw := NewSftpTestFramework(t, config)
+	err := fw.Setup(config)
+	require.NoError(t, err, "failed to setup test framework")
+	defer fw.Cleanup()
+
+	sftpClient, sshConn, err := fw.ConnectSFTP("testuser", "testuserpassword")
+	require.NoError(t, err, "failed to connect as testuser")
+	defer sshConn.Close()
+	defer sftpClient.Close()
+
+	t.Run("PathWithDotDot", func(t *testing.T) {
+		// Create directory structure
+		err := sftpClient.MkdirAll("/edge/subdir")
+		require.NoError(t, err)
+
+		// Create file using path with ..
+		file, err := sftpClient.Create("/edge/subdir/../file.txt")
+		require.NoError(t, err)
+		file.Write([]byte("test"))
+		file.Close()
+
+		// Verify file was created in /edge
+		_, err = sftpClient.Stat("/edge/file.txt")
+		require.NoError(t, err, "file should be created in parent directory")
+
+		// Clean up
+		sftpClient.Remove("/edge/file.txt")
+		sftpClient.RemoveDirectory("/edge/subdir")
+		sftpClient.RemoveDirectory("/edge")
+	})
+
+	t.Run("PathWithTrailingSlash", func(t *testing.T) {
+		err := sftpClient.Mkdir("/trailing")
+		require.NoError(t, err)
+
+		// Stat with trailing slash
+		info, err := sftpClient.Stat("/trailing/")
+		require.NoError(t, err)
+		require.True(t, info.IsDir())
+
+		// Clean up
+		sftpClient.RemoveDirectory("/trailing")
+	})
+
+	t.Run("CreateFileAtRootPath", func(t *testing.T) {
+		// This is the exact scenario from issue #7470
+		// User with HomeDir="/sftp/testuser" uploads to "/"
+		file, err := sftpClient.Create("/issue7470.txt")
+		require.NoError(t, err, "should be able to create file at / (issue #7470)")
+		file.Write([]byte("This tests the fix for issue #7470"))
+		file.Close()
+
+		// Verify
+		_, err = sftpClient.Stat("/issue7470.txt")
+		require.NoError(t, err)
+
+		// Clean up
+		sftpClient.Remove("/issue7470.txt")
+	})
+
+	// Security test: path traversal attacks should be blocked
+	t.Run("PathTraversalPrevention", func(t *testing.T) {
+		// User's HomeDir is "/sftp/testuser"
+		// Attempting to escape via "../.." should NOT create files outside home directory
+
+		// First, create a valid file to ensure we can write
+		validFile, err := sftpClient.Create("/valid.txt")
+		require.NoError(t, err)
+		validFile.Write([]byte("valid"))
+		validFile.Close()
+
+		// Try various path traversal attempts
+		// These should either:
+		// 1. Be blocked (error returned), OR
+		// 2. Be safely resolved to stay within home directory
+
+		traversalPaths := []string{
+			"/../escape.txt",
+			"/../../escape.txt",
+			"/../../../escape.txt",
+			"/subdir/../../escape.txt",
+			"/./../../escape.txt",
+		}
+
+		for _, traversalPath := range traversalPaths {
+			t.Run(traversalPath, func(t *testing.T) {
+				// Note: The pkg/sftp client sanitizes paths locally before sending them to the server.
+				// So "/../escape.txt" becomes "/escape.txt" on the wire.
+				// Therefore, we cannot trigger the server-side path traversal block with this client.
+				// Instead, we verify that the file is created successfully within the jail (contained).
+				// The server-side protection logic is verified in unit tests (sftpd/sftp_server_test.go).
+				
+				file, err := sftpClient.Create(traversalPath)
+				require.NoError(t, err, "creation should succeed because client sanitizes path")
+				file.Close()
+				
+				// Clean up
+				err = sftpClient.Remove(traversalPath)
+				require.NoError(t, err)
+			})
+		}
+
+		// Clean up
+		sftpClient.Remove("/valid.txt")
+	})
+}
+
+// TestFileContent tests reading and writing file content correctly
+func TestFileContent(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping integration test in short mode")
+	}
+
+	config := DefaultTestConfig()
+	config.EnableDebug = testing.Verbose()
+
+	fw := NewSftpTestFramework(t, config)
+	err := fw.Setup(config)
+	require.NoError(t, err, "failed to setup test framework")
+	defer fw.Cleanup()
+
+	sftpClient, sshConn, err := fw.ConnectSFTP("testuser", "testuserpassword")
+	require.NoError(t, err, "failed to connect as testuser")
+	defer sshConn.Close()
+	defer sftpClient.Close()
+
+	t.Run("BinaryContent", func(t *testing.T) {
+		// Create binary data with all byte values
+		data := make([]byte, 256)
+		for i := 0; i < 256; i++ {
+			data[i] = byte(i)
+		}
+
+		file, err := sftpClient.Create("/binary.bin")
+		require.NoError(t, err)
+		n, err := file.Write(data)
+		require.NoError(t, err)
+		require.Equal(t, 256, n)
+		file.Close()
+
+		// Read back
+		readFile, err := sftpClient.Open("/binary.bin")
+		require.NoError(t, err)
+		content, err := io.ReadAll(readFile)
+		require.NoError(t, err)
+		readFile.Close()
+
+		require.Equal(t, data, content, "binary content should match")
+
+		// Clean up
+		sftpClient.Remove("/binary.bin")
+	})
+
+	t.Run("EmptyFile", func(t *testing.T) {
+		file, err := sftpClient.Create("/empty.txt")
+		require.NoError(t, err)
+		file.Close()
+
+		info, err := sftpClient.Stat("/empty.txt")
+		require.NoError(t, err)
+		require.Equal(t, int64(0), info.Size())
+
+		// Clean up
+		sftpClient.Remove("/empty.txt")
+	})
+
+	t.Run("UnicodeFilename", func(t *testing.T) {
+		filename := "/文件名.txt"
+		content := []byte("Unicode content: 你好世界")
+
+		file, err := sftpClient.Create(filename)
+		require.NoError(t, err)
+		file.Write(content)
+		file.Close()
+
+		// Read back
+		readFile, err := sftpClient.Open(filename)
+		require.NoError(t, err)
+		readContent, err := io.ReadAll(readFile)
+		require.NoError(t, err)
+		readFile.Close()
+
+		require.Equal(t, content, readContent)
+
+		// Verify in listing
+		files, err := sftpClient.ReadDir("/")
+		require.NoError(t, err)
+		found := false
+		for _, f := range files {
+			if f.Name() == path.Base(filename) {
+				found = true
+				break
+			}
+		}
+		require.True(t, found, "should find unicode filename in listing")
+
+		// Clean up
+		sftpClient.Remove(filename)
+	})
+}
+

test/sftp/framework.go

@@ -0,0 +1,423 @@
+package sftp
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"syscall"
+	"testing"
+	"time"
+
+	"github.com/pkg/sftp"
+	"github.com/stretchr/testify/require"
+	"golang.org/x/crypto/ssh"
+)
+
+// SftpTestFramework provides utilities for SFTP integration testing
+type SftpTestFramework struct {
+	t             *testing.T
+	tempDir       string
+	dataDir       string
+	masterProcess *os.Process
+	volumeProcess *os.Process
+	filerProcess  *os.Process
+	sftpProcess   *os.Process
+	masterAddr    string
+	volumeAddr    string
+	filerAddr     string
+	sftpAddr      string
+	weedBinary    string
+	userStoreFile string
+	hostKeyFile   string
+	isSetup       bool
+	skipCleanup   bool
+}
+
+// TestConfig holds configuration for SFTP tests
+type TestConfig struct {
+	NumVolumes    int
+	EnableDebug   bool
+	SkipCleanup   bool // for debugging failed tests
+	UserStoreFile string
+}
+
+// DefaultTestConfig returns a default configuration for SFTP tests
+func DefaultTestConfig() *TestConfig {
+	return &TestConfig{
+		NumVolumes:    3,
+		EnableDebug:   false,
+		SkipCleanup:   false,
+		UserStoreFile: "",
+	}
+}
+
+// NewSftpTestFramework creates a new SFTP testing framework
+func NewSftpTestFramework(t *testing.T, config *TestConfig) *SftpTestFramework {
+	if config == nil {
+		config = DefaultTestConfig()
+	}
+
+	tempDir, err := os.MkdirTemp("", "seaweedfs_sftp_test_")
+	require.NoError(t, err)
+
+	// Generate SSH host key for SFTP server
+	hostKeyFile := filepath.Join(tempDir, "ssh_host_key")
+	cmd := exec.Command("ssh-keygen", "-t", "ed25519", "-f", hostKeyFile, "-N", "")
+	err = cmd.Run()
+	require.NoError(t, err, "failed to generate SSH host key")
+
+	// Use provided userstore or copy the test one
+	userStoreFile := config.UserStoreFile
+	if userStoreFile == "" {
+		// Copy test userstore to temp dir
+		userStoreFile = filepath.Join(tempDir, "userstore.json")
+		testDataPath := findTestDataPath()
+		input, err := os.ReadFile(filepath.Join(testDataPath, "userstore.json"))
+		require.NoError(t, err, "failed to read test userstore.json")
+		err = os.WriteFile(userStoreFile, input, 0644)
+		require.NoError(t, err, "failed to write userstore.json")
+	}
+
+	return &SftpTestFramework{
+		t:             t,
+		tempDir:       tempDir,
+		dataDir:       filepath.Join(tempDir, "data"),
+		masterAddr:    "127.0.0.1:19333",
+		volumeAddr:    "127.0.0.1:18080",
+		filerAddr:     "127.0.0.1:18888",
+		sftpAddr:      "127.0.0.1:12022",
+		weedBinary:    findWeedBinary(),
+		userStoreFile: userStoreFile,
+		hostKeyFile:   hostKeyFile,
+		isSetup:       false,
+	}
+}
+
+// Setup starts SeaweedFS cluster with SFTP server
+func (f *SftpTestFramework) Setup(config *TestConfig) error {
+	if f.isSetup {
+		return fmt.Errorf("framework already setup")
+	}
+
+	// Create all data directories
+	dirs := []string{
+		f.dataDir,
+		filepath.Join(f.dataDir, "master"),
+		filepath.Join(f.dataDir, "volume"),
+	}
+	for _, dir := range dirs {
+		if err := os.MkdirAll(dir, 0755); err != nil {
+			return fmt.Errorf("failed to create directory %s: %v", dir, err)
+		}
+	}
+
+	// Start master
+	if err := f.startMaster(config); err != nil {
+		return fmt.Errorf("failed to start master: %v", err)
+	}
+
+	// Wait for master to be ready
+	if err := f.waitForService(f.masterAddr, 30*time.Second); err != nil {
+		return fmt.Errorf("master not ready: %v", err)
+	}
+
+	// Start volume server
+	if err := f.startVolumeServer(config); err != nil {
+		return fmt.Errorf("failed to start volume server: %v", err)
+	}
+
+	// Wait for volume server to be ready
+	if err := f.waitForService(f.volumeAddr, 30*time.Second); err != nil {
+		return fmt.Errorf("volume server not ready: %v", err)
+	}
+
+	// Start filer
+	if err := f.startFiler(config); err != nil {
+		return fmt.Errorf("failed to start filer: %v", err)
+	}
+
+	// Wait for filer to be ready
+	if err := f.waitForService(f.filerAddr, 30*time.Second); err != nil {
+		return fmt.Errorf("filer not ready: %v", err)
+	}
+
+	// Start SFTP server
+	if err := f.startSftpServer(config); err != nil {
+		return fmt.Errorf("failed to start SFTP server: %v", err)
+	}
+
+	// Wait for SFTP server to be ready
+	if err := f.waitForService(f.sftpAddr, 30*time.Second); err != nil {
+		return fmt.Errorf("SFTP server not ready: %v", err)
+	}
+
+	// Additional wait for all services to stabilize (gRPC endpoints)
+	time.Sleep(500 * time.Millisecond)
+
+	f.skipCleanup = config.SkipCleanup
+	f.isSetup = true
+	return nil
+}
+
+// Cleanup stops all processes and removes temporary files
+func (f *SftpTestFramework) Cleanup() {
+	// Stop processes in reverse order
+	processes := []*os.Process{f.sftpProcess, f.filerProcess, f.volumeProcess, f.masterProcess}
+	for _, proc := range processes {
+		if proc != nil {
+			proc.Signal(syscall.SIGTERM)
+			proc.Wait()
+		}
+	}
+
+	// Remove temp directory
+	if !f.skipCleanup {
+		os.RemoveAll(f.tempDir)
+	}
+}
+
+// GetSftpAddr returns the SFTP server address
+func (f *SftpTestFramework) GetSftpAddr() string {
+	return f.sftpAddr
+}
+
+// GetFilerAddr returns the filer address
+func (f *SftpTestFramework) GetFilerAddr() string {
+	return f.filerAddr
+}
+
+// ConnectSFTP creates an SFTP client connection with the given credentials
+func (f *SftpTestFramework) ConnectSFTP(username, password string) (*sftp.Client, *ssh.Client, error) {
+	// Load the known host public key for verification
+	hostKeyCallback, err := f.getHostKeyCallback()
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to get host key callback: %v", err)
+	}
+
+	config := &ssh.ClientConfig{
+		User: username,
+		Auth: []ssh.AuthMethod{
+			ssh.Password(password),
+		},
+		HostKeyCallback: hostKeyCallback,
+		Timeout:         5 * time.Second,
+	}
+
+	sshConn, err := ssh.Dial("tcp", f.sftpAddr, config)
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to connect SSH: %v", err)
+	}
+
+	sftpClient, err := sftp.NewClient(sshConn)
+	if err != nil {
+		sshConn.Close()
+		return nil, nil, fmt.Errorf("failed to create SFTP client: %v", err)
+	}
+
+	return sftpClient, sshConn, nil
+}
+
+// getHostKeyCallback returns a callback that verifies the server's host key
+// matches the known test server key we generated
+func (f *SftpTestFramework) getHostKeyCallback() (ssh.HostKeyCallback, error) {
+	// Read the public key file generated alongside the private key
+	pubKeyFile := f.hostKeyFile + ".pub"
+	pubKeyBytes, err := os.ReadFile(pubKeyFile)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read host public key: %v", err)
+	}
+
+	// Parse the public key
+	pubKey, _, _, _, err := ssh.ParseAuthorizedKey(pubKeyBytes)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse host public key: %v", err)
+	}
+
+	// Return a callback that verifies the server key matches our known key
+	return ssh.FixedHostKey(pubKey), nil
+}
+
+// startMaster starts the SeaweedFS master server
+func (f *SftpTestFramework) startMaster(config *TestConfig) error {
+	args := []string{
+		"master",
+		"-ip=127.0.0.1",
+		"-port=19333",
+		"-mdir=" + filepath.Join(f.dataDir, "master"),
+		"-raftBootstrap",
+		"-peers=none",
+	}
+
+	cmd := exec.Command(f.weedBinary, args...)
+	cmd.Dir = f.tempDir
+	if config.EnableDebug {
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+	}
+	if err := cmd.Start(); err != nil {
+		return err
+	}
+	f.masterProcess = cmd.Process
+	return nil
+}
+
+// startVolumeServer starts SeaweedFS volume server
+func (f *SftpTestFramework) startVolumeServer(config *TestConfig) error {
+	args := []string{
+		"volume",
+		"-mserver=" + f.masterAddr,
+		"-ip=127.0.0.1",
+		"-port=18080",
+		"-dir=" + filepath.Join(f.dataDir, "volume"),
+		fmt.Sprintf("-max=%d", config.NumVolumes),
+	}
+
+	cmd := exec.Command(f.weedBinary, args...)
+	cmd.Dir = f.tempDir
+	if config.EnableDebug {
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+	}
+	if err := cmd.Start(); err != nil {
+		return err
+	}
+	f.volumeProcess = cmd.Process
+	return nil
+}
+
+// startFiler starts the SeaweedFS filer server
+func (f *SftpTestFramework) startFiler(config *TestConfig) error {
+	args := []string{
+		"filer",
+		"-master=" + f.masterAddr,
+		"-ip=127.0.0.1",
+		"-port=18888",
+	}
+
+	cmd := exec.Command(f.weedBinary, args...)
+	cmd.Dir = f.tempDir
+	if config.EnableDebug {
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+	}
+	if err := cmd.Start(); err != nil {
+		return err
+	}
+	f.filerProcess = cmd.Process
+	return nil
+}
+
+// startSftpServer starts the SeaweedFS SFTP server
+func (f *SftpTestFramework) startSftpServer(config *TestConfig) error {
+	args := []string{
+		"sftp",
+		"-filer=" + f.filerAddr,
+		"-ip.bind=127.0.0.1",
+		"-port=12022",
+		"-sshPrivateKey=" + f.hostKeyFile,
+		"-userStoreFile=" + f.userStoreFile,
+	}
+
+	cmd := exec.Command(f.weedBinary, args...)
+	cmd.Dir = f.tempDir
+	if config.EnableDebug {
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+	}
+	if err := cmd.Start(); err != nil {
+		return err
+	}
+	f.sftpProcess = cmd.Process
+	return nil
+}
+
+// waitForService waits for a service to be available
+func (f *SftpTestFramework) waitForService(addr string, timeout time.Duration) error {
+	deadline := time.Now().Add(timeout)
+	for time.Now().Before(deadline) {
+		conn, err := net.DialTimeout("tcp", addr, 1*time.Second)
+		if err == nil {
+			conn.Close()
+			return nil
+		}
+		time.Sleep(100 * time.Millisecond)
+	}
+	return fmt.Errorf("service at %s not ready within timeout", addr)
+}
+
+// findWeedBinary locates the weed binary
+// Prefers local build over system-installed weed to ensure we test the latest code
+func findWeedBinary() string {
+	// Get the directory where this source file is located
+	// This ensures we find the locally built weed binary first
+	_, thisFile, _, ok := runtime.Caller(0)
+	if ok {
+		thisDir := filepath.Dir(thisFile)
+		// From test/sftp/, the weed binary should be at ../../weed/weed
+		candidates := []string{
+			filepath.Join(thisDir, "../../weed/weed"),
+			filepath.Join(thisDir, "../weed/weed"),
+		}
+		for _, candidate := range candidates {
+			if _, err := os.Stat(candidate); err == nil {
+				abs, _ := filepath.Abs(candidate)
+				return abs
+			}
+		}
+	}
+
+	// Try relative paths from current working directory
+	cwd, _ := os.Getwd()
+	candidates := []string{
+		filepath.Join(cwd, "../../weed/weed"),
+		filepath.Join(cwd, "../weed/weed"),
+		filepath.Join(cwd, "./weed"),
+	}
+	for _, candidate := range candidates {
+		if _, err := os.Stat(candidate); err == nil {
+			abs, _ := filepath.Abs(candidate)
+			return abs
+		}
+	}
+
+	// Fallback to PATH only if local build not found
+	if path, err := exec.LookPath("weed"); err == nil {
+		return path
+	}
+
+	// Default fallback
+	return "weed"
+}
+
+// findTestDataPath locates the testdata directory
+func findTestDataPath() string {
+	// Get the directory where this source file is located
+	_, thisFile, _, ok := runtime.Caller(0)
+	if ok {
+		thisDir := filepath.Dir(thisFile)
+		testDataPath := filepath.Join(thisDir, "testdata")
+		if _, err := os.Stat(testDataPath); err == nil {
+			return testDataPath
+		}
+	}
+
+	// Try relative paths from current working directory
+	cwd, _ := os.Getwd()
+	candidates := []string{
+		filepath.Join(cwd, "testdata"),
+		filepath.Join(cwd, "../sftp/testdata"),
+		filepath.Join(cwd, "test/sftp/testdata"),
+	}
+
+	for _, candidate := range candidates {
+		if _, err := os.Stat(candidate); err == nil {
+			return candidate
+		}
+	}
+
+	return "./testdata"
+}
+

test/sftp/go.mod

@@ -0,0 +1,17 @@
+module seaweedfs-sftp-tests
+
+go 1.24.0
+
+require (
+	github.com/pkg/sftp v1.13.7
+	github.com/stretchr/testify v1.10.0
+	golang.org/x/crypto v0.45.0
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/kr/fs v0.1.0 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	golang.org/x/sys v0.38.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

test/sftp/go.sum

@@ -0,0 +1,64 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/kr/fs v0.1.0 h1:Jskdu9ieNAYnjxsi0LbQp1ulIKZV1LAFgK1tWhpZgl8=
+github.com/kr/fs v0.1.0/go.mod h1:FFnZGqtBN9Gxj7eW1uZ42v5BccTP0vu6NEaFoC2HwRg=
+github.com/pkg/sftp v1.13.7 h1:uv+I3nNJvlKZIQGSr8JVQLNHFU9YhhNpvC14Y6KgmSM=
+github.com/pkg/sftp v1.13.7/go.mod h1:KMKI0t3T6hfA+lTR/ssZdunHo+uwq7ghoN09/FSu3DY=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
+github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/crypto v0.17.0/go.mod h1:gCAAfMLgwOJRpTjQ2zCCt2OcSfYMTeZVSRtQlPC7Nq4=
+golang.org/x/crypto v0.45.0 h1:jMBrvKuj23MTlT0bQEOBcAE0mjg8mK9RXFhRH6nyF3Q=
+golang.org/x/crypto v0.45.0/go.mod h1:XTGrrkGJve7CYK7J8PEww4aY7gM3qMCElcJQ8n8JdX4=
+golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
+golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
+golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
+golang.org/x/net v0.6.0/go.mod h1:2Tu9+aMcznHK/AK1HMvgo6xiTLG5rD5rZLDS+rp2Bjs=
+golang.org/x/net v0.10.0/go.mod h1:0qNGK6F8kojg2nk9dLZ2mShWaEBan6FAoqfSigmmuDg=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.8.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.15.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.38.0 h1:3yZWxaJjBmCWXqhN1qh02AkOnCQ1poK6oF+a7xWL6Gc=
+golang.org/x/sys v0.38.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
+golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k=
+golang.org/x/term v0.8.0/go.mod h1:xPskH00ivmX89bAKVGSKKtLOWNx2+17Eiy94tnKShWo=
+golang.org/x/term v0.15.0/go.mod h1:BDl952bC7+uMoWR75FIrCDx79TPU9oHkTZ9yRbYOrX0=
+golang.org/x/term v0.37.0 h1:8EGAD0qCmHYZg6J17DvsMy9/wJ7/D/4pV/wfnld5lTU=
+golang.org/x/term v0.37.0/go.mod h1:5pB4lxRNYYVZuTLmy8oR2BH8dflOR+IbTYFD8fi3254=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
+golang.org/x/text v0.9.0/go.mod h1:e1OnstbJyHTd6l/uOt8jFFHp6TRDWZR/bV3emEE/zU8=
+golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
+golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

test/sftp/testdata/userstore.json

@@ -0,0 +1,36 @@
+[
+  {
+    "Username": "admin",
+    "Password": "adminpassword",
+    "PublicKeys": [],
+    "HomeDir": "/",
+    "Permissions": {
+      "/": ["*"]
+    },
+    "Uid": 0,
+    "Gid": 0
+  },
+  {
+    "Username": "testuser",
+    "Password": "testuserpassword",
+    "PublicKeys": [],
+    "HomeDir": "/sftp/testuser",
+    "Permissions": {
+      "/sftp/testuser": ["*"]
+    },
+    "Uid": 1001,
+    "Gid": 1001
+  },
+  {
+    "Username": "readonly",
+    "Password": "readonlypassword",
+    "PublicKeys": [],
+    "HomeDir": "/public",
+    "Permissions": {
+      "/public": ["read", "list"]
+    },
+    "Uid": 1002,
+    "Gid": 1002
+  }
+]
+

weed/sftpd/sftp_file_writer.go

@@ -72,6 +72,7 @@ func (l listerat) ListAt(ls []os.FileInfo, offset int64) (int, error) {
 type SeaweedSftpFileWriter struct {
 	fs          SftpServer
 	req         *sftp.Request
+	absPath     string // Absolute path after HomeDir translation
 	mu          sync.Mutex
 	tmpFile     *os.File
 	permissions os.FileMode
@@ -105,6 +106,6 @@ func (w *SeaweedSftpFileWriter) Close() error {
 		return err
 	}
 
-	// Stream the file instead of loading it
-	return w.fs.putFile(w.req.Filepath, w.tmpFile, w.fs.user)
+	// Stream the file to the absolute path (after HomeDir translation)
+	return w.fs.putFile(w.absPath, w.tmpFile, w.fs.user)
 }

weed/sftpd/sftp_filer.go

@@ -100,18 +100,26 @@ func (fs *SftpServer) withTimeoutContext(fn func(ctx context.Context) error) err
 // ==================== Command Dispatcher ====================
 
 func (fs *SftpServer) dispatchCmd(r *sftp.Request) error {
-	glog.V(0).Infof("Dispatch: %s %s", r.Method, r.Filepath)
+	absPath, err := fs.toAbsolutePath(r.Filepath)
+	if err != nil {
+		return err
+	}
+	glog.V(1).Infof("Dispatch: %s %s (absolute: %s)", r.Method, r.Filepath, absPath)
 	switch r.Method {
 	case "Remove":
-		return fs.removeEntry(r)
+		return fs.removeEntry(absPath)
 	case "Rename":
-		return fs.renameEntry(r)
+		absTarget, err := fs.toAbsolutePath(r.Target)
+		if err != nil {
+			return err
+		}
+		return fs.renameEntry(absPath, absTarget)
 	case "Mkdir":
-		return fs.makeDir(r)
+		return fs.makeDir(absPath)
 	case "Rmdir":
-		return fs.removeDir(r)
+		return fs.removeDir(absPath)
 	case "Setstat":
-		return fs.setFileStat(r)
+		return fs.setFileStatWithRequest(absPath, r)
 	default:
 		return fmt.Errorf("unsupported: %s", r.Method)
 	}
@@ -120,10 +128,14 @@ func (fs *SftpServer) dispatchCmd(r *sftp.Request) error {
 // ==================== File Operations ====================
 
 func (fs *SftpServer) readFile(r *sftp.Request) (io.ReaderAt, error) {
-	if err := fs.checkFilePermission(r.Filepath, "read"); err != nil {
+	absPath, err := fs.toAbsolutePath(r.Filepath)
+	if err != nil {
+		return nil, err
+	}
+	if err := fs.checkFilePermission(absPath, "read"); err != nil {
 		return nil, err
 	}
-	entry, err := fs.getEntry(r.Filepath)
+	entry, err := fs.getEntry(absPath)
 	if err != nil {
 		return nil, err
 	}
@@ -131,7 +143,11 @@ func (fs *SftpServer) readFile(r *sftp.Request) (io.ReaderAt, error) {
 }
 
 func (fs *SftpServer) newFileWriter(r *sftp.Request) (io.WriterAt, error) {
-	dir, _ := util.FullPath(r.Filepath).DirAndName()
+	absPath, err := fs.toAbsolutePath(r.Filepath)
+	if err != nil {
+		return nil, err
+	}
+	dir, _ := util.FullPath(absPath).DirAndName()
 	if err := fs.checkFilePermission(dir, "write"); err != nil {
 		glog.Errorf("Permission denied for %s", dir)
 		return nil, err
@@ -145,6 +161,7 @@ func (fs *SftpServer) newFileWriter(r *sftp.Request) (io.WriterAt, error) {
 	return &SeaweedSftpFileWriter{
 		fs:          *fs,
 		req:         r,
+		absPath:     absPath,
 		tmpFile:     tmpFile,
 		permissions: 0644,
 		uid:         fs.user.Uid,
@@ -153,16 +170,20 @@ func (fs *SftpServer) newFileWriter(r *sftp.Request) (io.WriterAt, error) {
 	}, nil
 }
 
-func (fs *SftpServer) removeEntry(r *sftp.Request) error {
-	return fs.deleteEntry(r.Filepath, false)
+func (fs *SftpServer) removeEntry(absPath string) error {
+	return fs.deleteEntry(absPath, false)
 }
 
-func (fs *SftpServer) renameEntry(r *sftp.Request) error {
-	if err := fs.checkFilePermission(r.Filepath, "rename"); err != nil {
+func (fs *SftpServer) renameEntry(absPath, absTarget string) error {
+	if err := fs.checkFilePermission(absPath, "rename"); err != nil {
+		return err
+	}
+	targetDir, _ := util.FullPath(absTarget).DirAndName()
+	if err := fs.checkFilePermission(targetDir, "write"); err != nil {
 		return err
 	}
-	oldDir, oldName := util.FullPath(r.Filepath).DirAndName()
-	newDir, newName := util.FullPath(r.Target).DirAndName()
+	oldDir, oldName := util.FullPath(absPath).DirAndName()
+	newDir, newName := util.FullPath(absTarget).DirAndName()
 	return fs.callWithClient(false, func(ctx context.Context, client filer_pb.SeaweedFilerClient) error {
 		_, err := client.AtomicRenameEntry(ctx, &filer_pb.AtomicRenameEntryRequest{
 			OldDirectory: oldDir, OldName: oldName,
@@ -172,15 +193,15 @@ func (fs *SftpServer) renameEntry(r *sftp.Request) error {
 	})
 }
 
-func (fs *SftpServer) setFileStat(r *sftp.Request) error {
-	if err := fs.checkFilePermission(r.Filepath, "write"); err != nil {
+func (fs *SftpServer) setFileStatWithRequest(absPath string, r *sftp.Request) error {
+	if err := fs.checkFilePermission(absPath, "write"); err != nil {
 		return err
 	}
-	entry, err := fs.getEntry(r.Filepath)
+	entry, err := fs.getEntry(absPath)
 	if err != nil {
 		return err
 	}
-	dir, _ := util.FullPath(r.Filepath).DirAndName()
+	dir, _ := util.FullPath(absPath).DirAndName()
 	// apply attrs
 	if r.AttrFlags().Permissions {
 		entry.Attributes.FileMode = uint32(r.Attributes().FileMode())
@@ -201,18 +222,22 @@ func (fs *SftpServer) setFileStat(r *sftp.Request) error {
 // ==================== Directory Operations ====================
 
 func (fs *SftpServer) listDir(r *sftp.Request) (sftp.ListerAt, error) {
-	if err := fs.checkFilePermission(r.Filepath, "list"); err != nil {
+	absPath, err := fs.toAbsolutePath(r.Filepath)
+	if err != nil {
+		return nil, err
+	}
+	if err := fs.checkFilePermission(absPath, "list"); err != nil {
 		return nil, err
 	}
 	if r.Method == "Stat" || r.Method == "Lstat" {
-		entry, err := fs.getEntry(r.Filepath)
+		entry, err := fs.getEntry(absPath)
 		if err != nil {
 			return nil, err
 		}
 		fi := &EnhancedFileInfo{FileInfo: FileInfoFromEntry(entry), uid: entry.Attributes.Uid, gid: entry.Attributes.Gid}
 		return listerat([]os.FileInfo{fi}), nil
 	}
-	return fs.listAllPages(r.Filepath)
+	return fs.listAllPages(absPath)
 }
 
 func (fs *SftpServer) listAllPages(dirPath string) (sftp.ListerAt, error) {
@@ -259,18 +284,19 @@ func (fs *SftpServer) fetchDirectoryPage(dirPath, start string) ([]os.FileInfo,
 }
 
 // makeDir creates a new directory with proper permissions.
-func (fs *SftpServer) makeDir(r *sftp.Request) error {
+func (fs *SftpServer) makeDir(absPath string) error {
 	if fs.user == nil {
 		return fmt.Errorf("cannot create directory: no user info")
 	}
-	dir, name := util.FullPath(r.Filepath).DirAndName()
-	if err := fs.checkFilePermission(r.Filepath, "mkdir"); err != nil {
+	dir, name := util.FullPath(absPath).DirAndName()
+	if err := fs.checkFilePermission(dir, "write"); err != nil {
 		return err
 	}
 	// default mode and ownership
 	err := filer_pb.Mkdir(context.Background(), fs, string(dir), name, func(entry *filer_pb.Entry) {
 		mode := uint32(0755 | os.ModeDir)
-		if strings.HasPrefix(r.Filepath, fs.user.HomeDir) {
+		// Defensive check: all paths should be under HomeDir after toAbsolutePath translation
+		if absPath == fs.user.HomeDir || strings.HasPrefix(absPath, fs.user.HomeDir+"/") {
 			mode = uint32(0700 | os.ModeDir)
 		}
 		entry.Attributes.FileMode = mode
@@ -288,8 +314,8 @@ func (fs *SftpServer) makeDir(r *sftp.Request) error {
 }
 
 // removeDir deletes a directory.
-func (fs *SftpServer) removeDir(r *sftp.Request) error {
-	return fs.deleteEntry(r.Filepath, false)
+func (fs *SftpServer) removeDir(absPath string) error {
+	return fs.deleteEntry(absPath, false)
 }
 
 func (fs *SftpServer) putFile(filepath string, reader io.Reader, user *user.User) error {

weed/sftpd/sftp_server.go

@@ -6,6 +6,8 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"path"
+	"strings"
 	"time"
 
 	"github.com/pkg/sftp"
@@ -37,6 +39,28 @@ func NewSftpServer(filerAddr pb.ServerAddress, grpcDialOption grpc.DialOption, d
 	}
 }
 
+// toAbsolutePath translates a user-relative path to an absolute filer path.
+// When a user has HomeDir="/sftp/user", their view of "/" maps to "/sftp/user".
+// This implements chroot-like behavior where the user's home directory
+// becomes their root.
+func (fs *SftpServer) toAbsolutePath(userPath string) (string, error) {
+	// If user has root as home directory, no translation needed
+	if fs.user.HomeDir == "" || fs.user.HomeDir == "/" {
+		return path.Clean(userPath), nil
+	}
+
+	// Concatenate home directory with user path, then clean to resolve any ".." components
+	p := path.Join(fs.user.HomeDir, strings.TrimPrefix(userPath, "/"))
+
+	// Security check: ensure the final path is within the home directory.
+	// This prevents path traversal attacks like `../..` that could escape the chroot jail.
+	if !strings.HasPrefix(p, fs.user.HomeDir+"/") && p != fs.user.HomeDir {
+		return "", fmt.Errorf("path traversal attempt: %s resolves to %s which is outside home dir %s", userPath, p, fs.user.HomeDir)
+	}
+
+	return p, nil
+}
+
 // Fileread is invoked for “get” requests.
 func (fs *SftpServer) Fileread(req *sftp.Request) (io.ReaderAt, error) {
 	return fs.readFile(req)

weed/sftpd/sftp_server_test.go

@@ -0,0 +1,103 @@
+package sftpd
+
+import (
+	"testing"
+
+	"github.com/seaweedfs/seaweedfs/weed/sftpd/user"
+	"github.com/stretchr/testify/assert"
+)
+
+func stringPtr(s string) *string {
+	return &s
+}
+
+func TestToAbsolutePath(t *testing.T) {
+	tests := []struct {
+		name        string
+		homeDir     *string // Use pointer to distinguish between unset and empty
+		userPath    string
+		expected    string
+		expectError bool
+	}{
+		{
+			name:     "normal path",
+			userPath: "/foo.txt",
+			expected: "/sftp/testuser/foo.txt",
+		},
+		{
+			name:     "root path",
+			userPath: "/",
+			expected: "/sftp/testuser",
+		},
+		{
+			name:     "path with dot",
+			userPath: "/./foo.txt",
+			expected: "/sftp/testuser/foo.txt",
+		},
+		{
+			name:        "path traversal attempts",
+			userPath:    "/../foo.txt",
+			expectError: true,
+		},
+		{
+			name:        "path traversal attempts 2",
+			userPath:    "../../foo.txt",
+			expectError: true,
+		},
+		{
+			name:        "path traversal attempts 3",
+			userPath:    "/subdir/../../foo.txt",
+			expectError: true,
+		},
+		{
+			name:     "empty path",
+			userPath: "",
+			expected: "/sftp/testuser",
+		},
+		{
+			name:     "multiple slashes",
+			userPath: "//foo.txt",
+			expected: "/sftp/testuser/foo.txt",
+		},
+		{
+			name:     "trailing slash",
+			userPath: "/foo/",
+			expected: "/sftp/testuser/foo",
+		},
+		{
+			name:     "empty HomeDir passthrough",
+			homeDir:  stringPtr(""),
+			userPath: "/foo.txt",
+			expected: "/foo.txt",
+		},
+		{
+			name:     "root HomeDir passthrough",
+			homeDir:  stringPtr("/"),
+			userPath: "/foo.txt",
+			expected: "/foo.txt",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			homeDir := "/sftp/testuser" // default
+			if tt.homeDir != nil {
+				homeDir = *tt.homeDir
+			}
+
+			fs := &SftpServer{
+				user: &user.User{
+					HomeDir: homeDir,
+				},
+			}
+
+			got, err := fs.toAbsolutePath(tt.userPath)
+			if tt.expectError {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+				assert.Equal(t, tt.expected, got)
+			}
+		})
+	}
+}

weed/sftpd/sftp_service.go

@@ -284,8 +284,8 @@ func (s *SFTPService) handleChannel(newChannel ssh.NewChannel, fs *SftpServer) {
 
 // handleSFTP starts the SFTP server on the SSH channel.
 func (s *SFTPService) handleSFTP(channel ssh.Channel, fs *SftpServer) {
-	// Create server options with initial working directory set to user's home
-	serverOptions := sftp.WithStartDirectory(fs.user.HomeDir)
+	// Start at virtual root "/" - toAbsolutePath translates this to the user's HomeDir
+	serverOptions := sftp.WithStartDirectory("/")
 	server := sftp.NewRequestServer(channel, sftp.Handlers{
 		FileGet:  fs,
 		FilePut:  fs,

weed/sftpd/user/filestore.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"os"
+	"path"
 	"sync"
 
 	"golang.org/x/crypto/ssh"
@@ -99,6 +100,10 @@ func (s *FileStore) loadUsers() error {
 				user.PublicKeys[i] = string(pubKey.Marshal())
 			}
 		}
+		// Clean HomeDir to handle trailing slashes and normalize path
+		if user.HomeDir != "" {
+			user.HomeDir = path.Clean(user.HomeDir)
+		}
 		s.users[user.Username] = user
 
 	}