summaryrefslogtreecommitdiff
path: root/internal/fusefrontend_reverse/root_node.go
blob: e15ddb043354d206b9a02a9d50c209ce28f8f210 (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
package fusefrontend_reverse

import (
	"log"
	"os"
	"path/filepath"
	"strings"
	"syscall"

	"github.com/rfjakob/gocryptfs/v2/internal/exitcodes"

	"github.com/rfjakob/gocryptfs/v2/internal/tlog"

	"golang.org/x/sys/unix"

	"github.com/hanwen/go-fuse/v2/fs"
	"github.com/hanwen/go-fuse/v2/fuse"

	"github.com/rfjakob/gocryptfs/v2/internal/contentenc"
	"github.com/rfjakob/gocryptfs/v2/internal/fusefrontend"
	"github.com/rfjakob/gocryptfs/v2/internal/inomap"
	"github.com/rfjakob/gocryptfs/v2/internal/nametransform"
	"github.com/rfjakob/gocryptfs/v2/internal/syscallcompat"

	"github.com/sabhiram/go-gitignore"
)

// RootNode is the root directory in a `gocryptfs -reverse` mount
type RootNode struct {
	Node
	// Stores configuration arguments
	args fusefrontend.Args
	// Filename encryption helper
	nameTransform *nametransform.NameTransform
	// Content encryption helper
	contentEnc *contentenc.ContentEnc
	// Tests whether a path is excluded (hidden) from the user. Used by -exclude.
	excluder ignore.IgnoreParser
	// inoMap translates inode numbers from different devices to unique inode
	// numbers.
	inoMap *inomap.InoMap
	// rootDev stores the device number of the backing directory. Used for
	// --one-file-system.
	rootDev uint64
}

// NewRootNode returns an encrypted FUSE overlay filesystem.
// In this case (reverse mode) the backing directory is plain-text and
// ReverseFS provides an encrypted view.
func NewRootNode(args fusefrontend.Args, c *contentenc.ContentEnc, n *nametransform.NameTransform) *RootNode {
	var rootDev uint64
	var st syscall.Stat_t
	if err := syscall.Stat(args.Cipherdir, &st); err != nil {
		tlog.Warn.Printf("Could not stat backing directory %q: %v", args.Cipherdir, err)
		if args.OneFileSystem {
			tlog.Fatal.Printf("This is a fatal error in combination with -one-file-system")
			os.Exit(exitcodes.CipherDir)
		}
	} else {
		rootDev = uint64(st.Dev)
	}

	rn := &RootNode{
		args:          args,
		nameTransform: n,
		contentEnc:    c,
		inoMap:        inomap.New(rootDev),
		rootDev:       rootDev,
	}
	if len(args.Exclude) > 0 || len(args.ExcludeWildcard) > 0 || len(args.ExcludeFrom) > 0 {
		rn.excluder = prepareExcluder(args)
	}
	return rn
}

// You can pass either gocryptfs.longname.XYZ.name or gocryptfs.longname.XYZ.
func (rn *RootNode) findLongnameParent(fd int, diriv []byte, longname string) (pName string, cFullName string, errno syscall.Errno) {
	defer func() {
		tlog.Debug.Printf("findLongnameParent: %d %x %q -> %q %q %d\n", fd, diriv, longname, pName, cFullName, errno)
	}()
	if strings.HasSuffix(longname, nametransform.LongNameSuffix) {
		longname = nametransform.RemoveLongNameSuffix(longname)
	}
	entries, err := syscallcompat.Getdents(fd)
	if err != nil {
		errno = fs.ToErrno(err)
		return
	}
	for _, entry := range entries {
		if len(entry.Name) <= shortNameMax {
			continue
		}
		cFullName, err = rn.nameTransform.EncryptName(entry.Name, diriv)
		if err != nil {
			continue
		}
		if len(cFullName) <= unix.NAME_MAX {
			// Entry should have been skipped by the shortNameMax check above
			log.Panic("logic error or wrong shortNameMax constant?")
		}
		hName := rn.nameTransform.HashLongName(cFullName)
		if longname == hName {
			pName = entry.Name
			break
		}
	}
	if pName == "" {
		errno = syscall.ENOENT
		return
	}
	return
}

// isExcludedPlain finds out if the plaintext path "pPath" is
// excluded (used when -exclude is passed by the user).
func (rn *RootNode) isExcludedPlain(pPath string) bool {
	// root dir can't be excluded
	if pPath == "" {
		return false
	}
	return rn.excluder != nil && rn.excluder.MatchesPath(pPath)
}

// excludeDirEntries filters out directory entries that are "-exclude"d.
// pDir is the relative plaintext path to the directory these entries are
// from. The entries should be plaintext files.
func (rn *RootNode) excludeDirEntries(d *dirfdPlus, entries []fuse.DirEntry) (filtered []fuse.DirEntry) {
	if rn.excluder == nil {
		return entries
	}
	filtered = make([]fuse.DirEntry, 0, len(entries))
	for _, entry := range entries {
		// filepath.Join handles the case of pDir="" correctly:
		// Join("", "foo") -> "foo". This does not: pDir + "/" + name"
		p := filepath.Join(d.pPath, entry.Name)
		if rn.isExcludedPlain(p) {
			// Skip file
			continue
		}
		filtered = append(filtered, entry)
	}
	return filtered
}