Statfs Namelen should be NAME_MAX not PATH_MAX

We accidentally set the wrong maximum. I've also added PATH_MAX and
NAME_MAX to the linux abi package.

PiperOrigin-RevId: 216221311
Change-Id: I44805fcf21508831809692184a0eba4cee469633

pkg/abi/linux/fs.go

@@ -28,6 +28,12 @@ const (
 	V9FS_MAGIC            = 0x01021997
 )
 
+// Filesystem path limits, from uapi/linux/limits.h.
+const (
+	NAME_MAX = 255
+	PATH_MAX = 4096
+)
+
 // Statfs is struct statfs, from uapi/asm-generic/statfs.h.
 type Statfs struct {
 	// Type is one of the filesystem magic values, defined above.

pkg/sentry/loader/elf.go

@@ -19,7 +19,6 @@ import (
 	"debug/elf"
 	"fmt"
 	"io"
-	"syscall"
 
 	"gvisor.googlesource.com/gvisor/pkg/abi"
 	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
@@ -409,7 +408,7 @@ func loadParsedELF(ctx context.Context, m *mm.MemoryManager, f *fs.File, info el
 				ctx.Infof("PT_INTERP path too small: %v", phdr.Filesz)
 				return loadedELF{}, syserror.ENOEXEC
 			}
-			if phdr.Filesz > syscall.PathMax {
+			if phdr.Filesz > linux.PATH_MAX {
 				ctx.Infof("PT_INTERP path too big: %v", phdr.Filesz)
 				return loadedELF{}, syserror.ENOEXEC
 			}

pkg/sentry/strace/strace.go

@@ -133,7 +133,7 @@ func dump(t *kernel.Task, addr usermem.Addr, size uint, maximumBlobSize uint) st
 }
 
 func path(t *kernel.Task, addr usermem.Addr) string {
-	path, err := t.CopyInString(addr, syscall.PathMax)
+	path, err := t.CopyInString(addr, linux.PATH_MAX)
 	if err != nil {
 		return fmt.Sprintf("%#x (error decoding path: %s)", addr, err)
 	}

pkg/sentry/syscalls/linux/sys_file.go

@@ -115,7 +115,7 @@ func fileOpOn(t *kernel.Task, dirFD kdefs.FD, path string, resolve bool, fn func
 
 // copyInPath copies a path in.
 func copyInPath(t *kernel.Task, addr usermem.Addr, allowEmpty bool) (path string, dirPath bool, err error) {
-	path, err = t.CopyInString(addr, syscall.PathMax)
+	path, err = t.CopyInString(addr, linux.PATH_MAX)
 	if err != nil {
 		return "", false, err
 	}
@@ -1080,7 +1080,7 @@ func symlinkAt(t *kernel.Task, dirFD kdefs.FD, newAddr usermem.Addr, oldAddr use
 
 	// The oldPath is copied in verbatim. This is because the symlink
 	// will include all details, including trailing slashes.
-	oldPath, err := t.CopyInString(oldAddr, syscall.PathMax)
+	oldPath, err := t.CopyInString(oldAddr, linux.PATH_MAX)
 	if err != nil {
 		return err
 	}

pkg/sentry/syscalls/linux/sys_stat.go

@@ -15,8 +15,6 @@
 package linux
 
 import (
-	"syscall"
-
 	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
@@ -198,7 +196,7 @@ func statfsImpl(t *kernel.Task, d *fs.Dirent, addr usermem.Addr) error {
 		Files:           info.TotalFiles,
 		FilesFree:       info.FreeFiles,
 		// Same as Linux for simple_statfs, see fs/libfs.c.
-		NameLength:   syscall.PathMax,
+		NameLength:   linux.NAME_MAX,
 		FragmentSize: d.Inode.StableAttr.BlockSize,
 		// Leave other fields 0 like simple_statfs does.
 	}

pkg/sentry/syscalls/linux/sys_thread.go

@@ -76,7 +76,7 @@ func Execve(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
 	envvAddr := args[2].Pointer()
 
 	// Extract our arguments.
-	filename, err := t.CopyInString(filenameAddr, syscall.PathMax)
+	filename, err := t.CopyInString(filenameAddr, linux.PATH_MAX)
 	if err != nil {
 		return 0, nil, err
 	}