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package fusefrontend
// This file forwards file encryption operations to cryptfs
import (
"path/filepath"
"strings"
"syscall"
"github.com/rfjakob/gocryptfs/internal/configfile"
"github.com/rfjakob/gocryptfs/internal/nametransform"
"github.com/rfjakob/gocryptfs/internal/syscallcompat"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
// isFiltered - check if plaintext "path" should be forbidden
//
// Prevents name clashes with internal files when file names are not encrypted
func (fs *FS) isFiltered(path string) bool {
if !fs.args.PlaintextNames {
return false
}
// gocryptfs.conf in the root directory is forbidden
if path == configfile.ConfDefaultName {
tlog.Info.Printf("The name /%s is reserved when -plaintextnames is used\n",
configfile.ConfDefaultName)
return true
}
// Note: gocryptfs.diriv is NOT forbidden because diriv and plaintextnames
// are exclusive
return false
}
// GetBackingPath - get the absolute encrypted path of the backing file
// from the relative plaintext path "relPath"
//
// TODO: this function is NOT symlink-safe.
func (fs *FS) getBackingPath(relPath string) (string, error) {
cPath, err := fs.encryptPath(relPath)
if err != nil {
return "", err
}
cAbsPath := filepath.Join(fs.args.Cipherdir, cPath)
tlog.Debug.Printf("getBackingPath: %s + %s -> %s", fs.args.Cipherdir, relPath, cAbsPath)
return cAbsPath, nil
}
// openBackingDir opens the parent ciphertext directory of plaintext path
// "relPath" and returns the dirfd and the encrypted basename.
//
// The caller should then use Openat(dirfd, cName, ...) and friends.
// For convenience, if relPath is "", cName is going to be ".".
//
// openBackingDir is secure against symlink races by using Openat and
// ReadDirIVAt.
func (fs *FS) openBackingDir(relPath string) (dirfd int, cName string, err error) {
// With PlaintextNames, we don't need to read DirIVs. Easy.
if fs.args.PlaintextNames {
dir := nametransform.Dir(relPath)
dirfd, err = syscallcompat.OpenDirNofollow(fs.args.Cipherdir, dir)
if err != nil {
return -1, "", err
}
// If relPath is empty, cName is ".".
cName = filepath.Base(relPath)
return dirfd, cName, nil
}
// Open cipherdir (following symlinks)
dirfd, err = syscall.Open(fs.args.Cipherdir, syscall.O_RDONLY|syscall.O_DIRECTORY|syscallcompat.O_PATH, 0)
if err != nil {
return -1, "", err
}
// If relPath is empty, cName is ".".
if relPath == "" {
return dirfd, ".", nil
}
// Walk the directory tree
parts := strings.Split(relPath, "/")
for i, name := range parts {
iv, err := nametransform.ReadDirIVAt(dirfd)
if err != nil {
return -1, "", err
}
cName = fs.nameTransform.EncryptAndHashName(name, iv)
// Last part? We are done.
if i == len(parts)-1 {
break
}
// Not the last part? Descend into next directory.
dirfd2, err := syscallcompat.Openat(dirfd, cName, syscall.O_RDONLY|syscall.O_NOFOLLOW|syscall.O_DIRECTORY|syscallcompat.O_PATH, 0)
syscall.Close(dirfd)
if err != nil {
return -1, "", err
}
dirfd = dirfd2
}
return dirfd, cName, nil
}
// encryptPath - encrypt relative plaintext path
//
// TODO: this function is NOT symlink-safe because EncryptPathDirIV is not
// symlink-safe.
func (fs *FS) encryptPath(plainPath string) (string, error) {
if plainPath != "" { // Empty path gets encrypted all the time without actual file accesses.
fs.AccessedSinceLastCheck = 1
} else { // Empty string gets encrypted as empty string
return plainPath, nil
}
if fs.args.PlaintextNames {
return plainPath, nil
}
fs.dirIVLock.RLock()
cPath, err := fs.nameTransform.EncryptPathDirIV(plainPath, fs.args.Cipherdir)
tlog.Debug.Printf("encryptPath '%s' -> '%s' (err: %v)", plainPath, cPath, err)
fs.dirIVLock.RUnlock()
return cPath, err
}
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