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package fusefrontend
import (
"context"
"path/filepath"
"syscall"
"golang.org/x/sys/unix"
"github.com/hanwen/go-fuse/v2/fs"
"github.com/hanwen/go-fuse/v2/fuse"
"github.com/rfjakob/gocryptfs/internal/configfile"
"github.com/rfjakob/gocryptfs/internal/nametransform"
"github.com/rfjakob/gocryptfs/internal/syscallcompat"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
// mkdirWithIv - create a new directory and corresponding diriv file. dirfd
// should be a handle to the parent directory, cName is the name of the new
// directory and mode specifies the access permissions to use.
func (n *Node) mkdirWithIv(dirfd int, cName string, mode uint32, caller *fuse.Caller) error {
rn := n.rootNode()
// Between the creation of the directory and the creation of gocryptfs.diriv
// the directory is inconsistent. Take the lock to prevent other readers
// from seeing it.
rn.dirIVLock.Lock()
defer rn.dirIVLock.Unlock()
err := syscallcompat.MkdiratUser(dirfd, cName, mode, caller)
if err != nil {
return err
}
dirfd2, err := syscallcompat.Openat(dirfd, cName, syscall.O_DIRECTORY|syscall.O_NOFOLLOW|syscallcompat.O_PATH, 0)
if err == nil {
// Create gocryptfs.diriv
err = nametransform.WriteDirIVAt(dirfd2)
syscall.Close(dirfd2)
}
if err != nil {
// Delete inconsistent directory (missing gocryptfs.diriv!)
err2 := syscallcompat.Unlinkat(dirfd, cName, unix.AT_REMOVEDIR)
if err2 != nil {
tlog.Warn.Printf("mkdirWithIv: rollback failed: %v", err2)
}
}
return err
}
// Mkdir - FUSE call. Create a directory at "newPath" with permissions "mode".
//
// Symlink-safe through use of Mkdirat().
func (n *Node) Mkdir(ctx context.Context, name string, mode uint32, out *fuse.EntryOut) (*fs.Inode, syscall.Errno) {
rn := n.rootNode()
newPath := filepath.Join(n.path(), name)
if rn.isFiltered(newPath) {
return nil, syscall.EPERM
}
dirfd, cName, err := rn.openBackingDir(newPath)
if err != nil {
return nil, fs.ToErrno(err)
}
defer syscall.Close(dirfd)
var caller *fuse.Caller
if rn.args.PreserveOwner {
caller, _ = fuse.FromContext(ctx)
}
if rn.args.PlaintextNames {
err = syscallcompat.MkdiratUser(dirfd, cName, mode, caller)
return nil, fs.ToErrno(err)
}
// We need write and execute permissions to create gocryptfs.diriv.
// Also, we need read permissions to open the directory (to avoid
// race-conditions between getting and setting the mode).
origMode := mode
mode = mode | 0700
// Handle long file name
if nametransform.IsLongContent(cName) {
// Create ".name"
err = rn.nameTransform.WriteLongNameAt(dirfd, cName, newPath)
if err != nil {
return nil, fs.ToErrno(err)
}
// Create directory
err = rn.mkdirWithIv(dirfd, cName, mode, caller)
if err != nil {
nametransform.DeleteLongNameAt(dirfd, cName)
return nil, fs.ToErrno(err)
}
} else {
err = rn.mkdirWithIv(dirfd, cName, mode, caller)
if err != nil {
return nil, fs.ToErrno(err)
}
}
fd, err := syscallcompat.Openat(dirfd, cName,
syscall.O_RDONLY|syscall.O_DIRECTORY|syscall.O_NOFOLLOW, 0)
if err != nil {
tlog.Warn.Printf("Mkdir %q: Openat failed: %v", cName, err)
return nil, fs.ToErrno(err)
}
defer syscall.Close(fd)
// Get unique inode number
var st syscall.Stat_t
err = syscall.Fstat(fd, &st)
if err != nil {
tlog.Warn.Printf("Mkdir %q: Fstat failed: %v", cName, err)
return nil, fs.ToErrno(err)
}
rn.inoMap.TranslateStat(&st)
out.Attr.FromStat(&st)
// Create child node
id := fs.StableAttr{
Mode: uint32(st.Mode),
Gen: 1,
Ino: st.Ino,
}
node := &Node{}
ch := n.NewInode(ctx, node, id)
// Set mode
if origMode != mode {
// Preserve SGID bit if it was set due to inheritance.
origMode = uint32(st.Mode&^0777) | origMode
err = syscall.Fchmod(fd, origMode)
if err != nil {
tlog.Warn.Printf("Mkdir %q: Fchmod %#o -> %#o failed: %v", cName, mode, origMode, err)
}
}
return ch, 0
}
func (n *Node) Readdir(ctx context.Context) (fs.DirStream, syscall.Errno) {
rn := n.rootNode()
p := n.path()
dirName := filepath.Base(p)
parentDirFd, cDirName, err := rn.openBackingDir(p)
if err != nil {
return nil, fs.ToErrno(err)
}
defer syscall.Close(parentDirFd)
// Read ciphertext directory
var cipherEntries []fuse.DirEntry
fd, err := syscallcompat.Openat(parentDirFd, cDirName, syscall.O_RDONLY|syscall.O_DIRECTORY|syscall.O_NOFOLLOW, 0)
if err != nil {
return nil, fs.ToErrno(err)
}
defer syscall.Close(fd)
cipherEntries, err = syscallcompat.Getdents(fd)
if err != nil {
return nil, fs.ToErrno(err)
}
// Get DirIV (stays nil if PlaintextNames is used)
var cachedIV []byte
if !rn.args.PlaintextNames {
// Read the DirIV from disk
cachedIV, err = nametransform.ReadDirIVAt(fd)
if err != nil {
tlog.Warn.Printf("OpenDir %q: could not read %s: %v", cDirName, nametransform.DirIVFilename, err)
return nil, syscall.EIO
}
}
// Decrypted directory entries
var plain []fuse.DirEntry
// Filter and decrypt filenames
for i := range cipherEntries {
cName := cipherEntries[i].Name
if dirName == "." && cName == configfile.ConfDefaultName {
// silently ignore "gocryptfs.conf" in the top level dir
continue
}
if rn.args.PlaintextNames {
plain = append(plain, cipherEntries[i])
continue
}
if cName == nametransform.DirIVFilename {
// silently ignore "gocryptfs.diriv" everywhere if dirIV is enabled
continue
}
// Handle long file name
isLong := nametransform.LongNameNone
if rn.args.LongNames {
isLong = nametransform.NameType(cName)
}
if isLong == nametransform.LongNameContent {
cNameLong, err := nametransform.ReadLongNameAt(fd, cName)
if err != nil {
tlog.Warn.Printf("OpenDir %q: invalid entry %q: Could not read .name: %v",
cDirName, cName, err)
rn.reportMitigatedCorruption(cName)
continue
}
cName = cNameLong
} else if isLong == nametransform.LongNameFilename {
// ignore "gocryptfs.longname.*.name"
continue
}
name, err := rn.nameTransform.DecryptName(cName, cachedIV)
if err != nil {
tlog.Warn.Printf("OpenDir %q: invalid entry %q: %v",
cDirName, cName, err)
rn.reportMitigatedCorruption(cName)
continue
}
// Override the ciphertext name with the plaintext name but reuse the rest
// of the structure
cipherEntries[i].Name = name
plain = append(plain, cipherEntries[i])
}
return fs.NewListDirStream(plain), 0
}
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