diff options
Diffstat (limited to 'internal')
-rw-r--r-- | internal/fusefrontend/file.go | 16 | ||||
-rw-r--r-- | internal/fusefrontend/file_lock.go | 29 | ||||
-rw-r--r-- | internal/syscallcompat/sys_darwin.go | 4 | ||||
-rw-r--r-- | internal/syscallcompat/sys_linux.go | 1 |
4 files changed, 50 insertions, 0 deletions
diff --git a/internal/fusefrontend/file.go b/internal/fusefrontend/file.go index 8d0ba01..9bd05e6 100644 --- a/internal/fusefrontend/file.go +++ b/internal/fusefrontend/file.go @@ -14,6 +14,8 @@ import ( "sync" "syscall" + "golang.org/x/sys/unix" + "github.com/hanwen/go-fuse/v2/fs" "github.com/hanwen/go-fuse/v2/fuse" @@ -91,6 +93,13 @@ func (f *File) readFileID() ([]byte, error) { // and not only the header. A header-only file will be considered empty. // This makes File ID poisoning more difficult. readLen := contentenc.HeaderLen + 1 + if f.rootNode.args.SharedStorage { + // With -sharedstorage, we consider a header-only file as valid, because + // another gocryptfs process may have either: + // 1) just created the header, and not written further data yet. + // 2) truncated the file down to just the header. + readLen = contentenc.HeaderLen + } buf := make([]byte, readLen) n, err := f.fd.ReadAt(buf, 0) if err != nil { @@ -267,18 +276,25 @@ func (f *File) doWrite(data []byte, off int64) (uint32, syscall.Errno) { // // If the file ID is not cached, read it from disk if f.fileTableEntry.ID == nil { + if err := f.LockSharedStorage(unix.F_WRLCK, 0, contentenc.HeaderLen); err != nil { + return 0, fs.ToErrno(err) + } var err error fileID, err := f.readFileID() // Write a new file header if the file is empty if err == io.EOF { fileID, err = f.createHeader() fileWasEmpty = true + // Having the unlock three times is ugly. But every other way I tried is even uglier. + f.LockSharedStorage(unix.F_UNLCK, 0, contentenc.HeaderLen) } else if err != nil { // Other errors mean readFileID() found a corrupt header tlog.Warn.Printf("doWrite %d: corrupt header: %v", f.qIno.Ino, err) + f.LockSharedStorage(unix.F_UNLCK, 0, contentenc.HeaderLen) return 0, syscall.EIO } if err != nil { + f.LockSharedStorage(unix.F_UNLCK, 0, contentenc.HeaderLen) return 0, fs.ToErrno(err) } f.fileTableEntry.ID = fileID diff --git a/internal/fusefrontend/file_lock.go b/internal/fusefrontend/file_lock.go new file mode 100644 index 0000000..6f92cfe --- /dev/null +++ b/internal/fusefrontend/file_lock.go @@ -0,0 +1,29 @@ +package fusefrontend + +import ( + "golang.org/x/sys/unix" + + "github.com/rfjakob/gocryptfs/v2/internal/syscallcompat" +) + +// SharedStorageLock conveniently wraps F_OFD_SETLKW +// See https://man7.org/linux/man-pages/man2/fcntl.2.html -> "Open file description locks (non-POSIX)" +// +// lkType is one of: +// * unix.F_RDLCK (shared read lock) +// * unix.F_WRLCK (exclusive write lock) +// * unix.F_UNLCK (unlock) +// +// This function is a no-op if args.SharedStorage == false. +func (f *File) LockSharedStorage(lkType int16, lkStart int64, lkLen int64) error { + if !f.rootNode.args.SharedStorage { + return nil + } + lk := unix.Flock_t{ + Type: lkType, + Whence: unix.SEEK_SET, + Start: lkStart, + Len: lkLen, + } + return unix.FcntlFlock(uintptr(f.intFd()), syscallcompat.F_OFD_SETLKW, &lk) +} diff --git a/internal/syscallcompat/sys_darwin.go b/internal/syscallcompat/sys_darwin.go index 06f09f0..b13b6a5 100644 --- a/internal/syscallcompat/sys_darwin.go +++ b/internal/syscallcompat/sys_darwin.go @@ -27,6 +27,10 @@ const ( RENAME_EXCHANGE = 2 RENAME_WHITEOUT = 4 + // F_OFD_SETLKW only exists on Linux. On Darwin, fall back to F_SETLKW as a + // flawed replacement. + F_OFD_SETLKW = unix.F_SETLKW + // KAUTH_UID_NONE and KAUTH_GID_NONE are special values to // revert permissions to the process credentials. KAUTH_UID_NONE = ^uint32(0) - 100 diff --git a/internal/syscallcompat/sys_linux.go b/internal/syscallcompat/sys_linux.go index a64b27e..3714b75 100644 --- a/internal/syscallcompat/sys_linux.go +++ b/internal/syscallcompat/sys_linux.go @@ -32,6 +32,7 @@ const ( RENAME_NOREPLACE = unix.RENAME_NOREPLACE RENAME_WHITEOUT = unix.RENAME_WHITEOUT RENAME_EXCHANGE = unix.RENAME_EXCHANGE + F_OFD_SETLKW = unix.F_OFD_SETLKW ) var preallocWarn sync.Once |