aboutsummaryrefslogtreecommitdiff
path: root/internal/fusefrontend/fs_dir.go
blob: aed501da0a58a959283caf06a6db00727a72b82b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
package fusefrontend

// Mkdir and Rmdir

import (
	"fmt"
	"os"
	"path/filepath"
	"syscall"

	"github.com/hanwen/go-fuse/fuse"

	"github.com/rfjakob/gocryptfs/internal/cryptocore"
	"github.com/rfjakob/gocryptfs/internal/nametransform"
	"github.com/rfjakob/gocryptfs/internal/toggledlog"
)

func (fs *FS) Mkdir(relPath string, mode uint32, context *fuse.Context) (code fuse.Status) {
	if fs.isFiltered(relPath) {
		return fuse.EPERM
	}
	encPath, err := fs.getBackingPath(relPath)
	if err != nil {
		return fuse.ToStatus(err)
	}
	if !fs.args.DirIV {
		return fuse.ToStatus(os.Mkdir(encPath, os.FileMode(mode)))
	}

	// We need write and execute permissions to create gocryptfs.diriv
	origMode := mode
	mode = mode | 0300

	// The new directory may take the place of an older one that is still in the cache
	fs.nameTransform.DirIVCache.Clear()
	// Create directory
	fs.dirIVLock.Lock()
	defer fs.dirIVLock.Unlock()
	err = os.Mkdir(encPath, os.FileMode(mode))
	if err != nil {
		return fuse.ToStatus(err)
	}
	// Create gocryptfs.diriv inside
	err = nametransform.WriteDirIV(encPath)
	if err != nil {
		// This should not happen
		toggledlog.Warn.Printf("Mkdir: WriteDirIV failed: %v", err)
		err2 := syscall.Rmdir(encPath)
		if err2 != nil {
			toggledlog.Warn.Printf("Mkdir: Rmdir rollback failed: %v", err2)
		}
		return fuse.ToStatus(err)
	}

	// Set permissions back to what the user wanted
	if origMode != mode {
		err = os.Chmod(encPath, os.FileMode(origMode))
		if err != nil {
			toggledlog.Warn.Printf("Mkdir: Chmod failed: %v", err)
		}
	}

	return fuse.OK
}

func (fs *FS) Rmdir(name string, context *fuse.Context) (code fuse.Status) {
	encPath, err := fs.getBackingPath(name)
	if err != nil {
		return fuse.ToStatus(err)
	}
	if !fs.args.DirIV {
		return fuse.ToStatus(syscall.Rmdir(encPath))
	}

	// If the directory is not empty besides gocryptfs.diriv, do not even
	// attempt the dance around gocryptfs.diriv.
	fd, err := os.Open(encPath)
	if perr, ok := err.(*os.PathError); ok && perr.Err == syscall.EACCES {
		// We need permission to read and modify the directory
		toggledlog.Debug.Printf("Rmdir: handling EACCESS")
		fi, err2 := os.Stat(encPath)
		if err2 != nil {
			toggledlog.Debug.Printf("Rmdir: Stat: %v", err2)
			return fuse.ToStatus(err2)
		}
		origMode := fi.Mode()
		newMode := origMode | 0700
		err2 = os.Chmod(encPath, newMode)
		if err2 != nil {
			toggledlog.Debug.Printf("Rmdir: Chmod failed: %v", err2)
			return fuse.ToStatus(err)
		}
		defer func() {
			if code != fuse.OK {
				// Undo the chmod if removing the directory failed
				err3 := os.Chmod(encPath, origMode)
				if err3 != nil {
					toggledlog.Warn.Printf("Rmdir: Chmod rollback failed: %v", err2)
				}
			}
		}()
		// Retry open
		fd, err = os.Open(encPath)
	}
	if err != nil {
		toggledlog.Debug.Printf("Rmdir: Open: %v", err)
		return fuse.ToStatus(err)
	}
	list, err := fd.Readdirnames(10)
	fd.Close()
	if err != nil {
		toggledlog.Debug.Printf("Rmdir: Readdirnames: %v", err)
		return fuse.ToStatus(err)
	}
	if len(list) > 1 {
		return fuse.ToStatus(syscall.ENOTEMPTY)
	} else if len(list) == 0 {
		toggledlog.Warn.Printf("Rmdir: gocryptfs.diriv missing, allowing deletion")
		return fuse.ToStatus(syscall.Rmdir(encPath))
	}

	// Move "gocryptfs.diriv" to the parent dir as "gocryptfs.diriv.rmdir.XYZ"
	dirivPath := filepath.Join(encPath, nametransform.DirIVFilename)
	parentDir := filepath.Dir(encPath)
	tmpName := fmt.Sprintf("gocryptfs.diriv.rmdir.%d", cryptocore.RandUint64())
	tmpDirivPath := filepath.Join(parentDir, tmpName)
	toggledlog.Debug.Printf("Rmdir: Renaming %s to %s", nametransform.DirIVFilename, tmpDirivPath)
	// The directory is in an inconsistent state between rename and rmdir. Protect against
	// concurrent readers.
	fs.dirIVLock.Lock()
	defer fs.dirIVLock.Unlock()
	err = os.Rename(dirivPath, tmpDirivPath)
	if err != nil {
		toggledlog.Warn.Printf("Rmdir: Renaming %s to %s failed: %v",
			nametransform.DirIVFilename, tmpDirivPath, err)
		return fuse.ToStatus(err)
	}
	// Actual Rmdir
	err = syscall.Rmdir(encPath)
	if err != nil {
		// This can happen if another file in the directory was created in the
		// meantime, undo the rename
		err2 := os.Rename(tmpDirivPath, dirivPath)
		if err2 != nil {
			toggledlog.Warn.Printf("Rmdir: Rename rollback failed: %v", err2)
		}
		return fuse.ToStatus(err)
	}
	// Delete "gocryptfs.diriv.rmdir.INODENUMBER"
	err = syscall.Unlink(tmpDirivPath)
	if err != nil {
		toggledlog.Warn.Printf("Rmdir: Could not clean up %s: %v", tmpName, err)
	}
	// The now-deleted directory may have been in the DirIV cache. Clear it.
	fs.nameTransform.DirIVCache.Clear()
	return fuse.OK
}