aboutsummaryrefslogtreecommitdiff
path: root/internal/fusefrontend_reverse/reverse_longnames.go
blob: 6409d95a1f02adf84780fbc8486252a0f4acbca6 (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
package fusefrontend_reverse

import (
	"os"
	"path/filepath"
	"sync"
	"syscall"
	"time"

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

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

const (
	shortNameMax = 176
)

var longnameParentCache map[string]string
var longnameCacheLock sync.Mutex

// Very simple cache cleaner: Nuke it every hour
func longnameCacheCleaner() {
	for {
		time.Sleep(time.Hour)
		longnameCacheLock.Lock()
		longnameParentCache = map[string]string{}
		longnameCacheLock.Unlock()
	}
}

func init() {
	longnameParentCache = map[string]string{}
	go longnameCacheCleaner()
}

// findLongnameParent converts "gocryptfs.longname.XYZ" to the plaintext name
func (rfs *reverseFS) findLongnameParent(dir string, dirIV []byte, longname string) (plaintextName string, err error) {
	longnameCacheLock.Lock()
	hit := longnameParentCache[longname]
	longnameCacheLock.Unlock()
	if hit != "" {
		return hit, nil
	}
	absDir := filepath.Join(rfs.args.Cipherdir, dir)
	dirfd, err := os.Open(absDir)
	if err != nil {
		return "", err
	}
	dirEntries, err := dirfd.Readdirnames(-1)
	if err != nil {
		return "", err
	}
	longnameCacheLock.Lock()
	defer longnameCacheLock.Unlock()
	for _, plaintextName = range dirEntries {
		if len(plaintextName) <= shortNameMax {
			continue
		}
		cName := rfs.nameTransform.EncryptName(plaintextName, dirIV)
		if len(cName) <= syscall.NAME_MAX {
			panic("logic error or wrong shortNameMax constant?")
		}
		hName := nametransform.HashLongName(cName)
		longnameParentCache[hName] = plaintextName
		if longname == hName {
			hit = plaintextName
		}
	}
	if hit == "" {
		return "", syscall.ENOENT
	} else {
		return hit, nil
	}
}

func (rfs *reverseFS) newNameFile(relPath string) (nodefs.File, fuse.Status) {
	dotName := filepath.Base(relPath)                                    // gocryptfs.longname.XYZ.name
	longname := dotName[:len(dotName)-len(nametransform.LongNameSuffix)] // gocryptfs.longname.XYZ

	cDir := saneDir(relPath)
	pDir, err := rfs.decryptPath(cDir)
	if err != nil {
		return nil, fuse.ToStatus(err)
	}
	dirIV := derivePathIV(cDir)
	e, err := rfs.findLongnameParent(pDir, dirIV, longname)
	if err != nil {
		return nil, fuse.ToStatus(err)
	}
	content := []byte(rfs.nameTransform.EncryptName(e, dirIV))
	parentFile := filepath.Join(rfs.args.Cipherdir, pDir)
	return rfs.NewVirtualFile(content, parentFile)
}