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fileOp{On,At} should pass the remaning symlink traversal count. 

And methods that do more traversals should use the remaining count rather than
resetting.

PiperOrigin-RevId: 254041720
This commit is contained in:
Nicolas Lacasse 2019-06-19 11:55:22 -07:00 committed by gVisor bot
parent f7428af9c1
commit 29f9e4fa87
4 changed files with 35 additions and 36 deletions
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57
pkg/sentry/syscalls/linux/sys_file.go
View File

@ -35,13 +35,13 @@ import (
)
// fileOpAt performs an operation on the second last component in the path.
func fileOpAt(t *kernel.Task, dirFD kdefs.FD, path string, fn func(root *fs.Dirent, d *fs.Dirent, name string) error) error {
func fileOpAt(t *kernel.Task, dirFD kdefs.FD, path string, fn func(root *fs.Dirent, d *fs.Dirent, name string, remainingTraversals uint) error) error {
// Extract the last component.
dir, name := fs.SplitLast(path)
if dir == "/" {
// Common case: we are accessing a file in the root.
root := t.FSContext().RootDirectory()
err := fn(root, root, name)
err := fn(root, root, name, linux.MaxSymlinkTraversals)
root.DecRef()
return err
} else if dir == "." && dirFD == linux.AT_FDCWD {
@ -49,19 +49,19 @@ func fileOpAt(t *kernel.Task, dirFD kdefs.FD, path string, fn func(root *fs.Dire
// working directory; skip the look-up.
wd := t.FSContext().WorkingDirectory()
root := t.FSContext().RootDirectory()
err := fn(root, wd, name)
err := fn(root, wd, name, linux.MaxSymlinkTraversals)
wd.DecRef()
root.DecRef()
return err
}
return fileOpOn(t, dirFD, dir, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent) error {
return fn(root, d, name)
return fileOpOn(t, dirFD, dir, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent, remainingTraversals uint) error {
return fn(root, d, name, remainingTraversals)
})
}
// fileOpOn performs an operation on the last entry of the path.
func fileOpOn(t *kernel.Task, dirFD kdefs.FD, path string, resolve bool, fn func(root *fs.Dirent, d *fs.Dirent) error) error {
func fileOpOn(t *kernel.Task, dirFD kdefs.FD, path string, resolve bool, fn func(root *fs.Dirent, d *fs.Dirent, remainingTraversals uint) error) error {
var (
d *fs.Dirent // The file.
wd *fs.Dirent // The working directory (if required.)
@ -110,7 +110,7 @@ func fileOpOn(t *kernel.Task, dirFD kdefs.FD, path string, resolve bool, fn func
return err
}
err = fn(root, d)
err = fn(root, d, remainingTraversals)
d.DecRef()
return err
}
@ -139,7 +139,7 @@ func openAt(t *kernel.Task, dirFD kdefs.FD, addr usermem.Addr, flags uint) (fd u
}
resolve := flags&linux.O_NOFOLLOW == 0
err = fileOpOn(t, dirFD, path, resolve, func(root *fs.Dirent, d *fs.Dirent) error {
err = fileOpOn(t, dirFD, path, resolve, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
// First check a few things about the filesystem before trying to get the file
// reference.
//
@ -211,7 +211,7 @@ func mknodAt(t *kernel.Task, dirFD kdefs.FD, addr usermem.Addr, mode linux.FileM
return syserror.ENOENT
}
return fileOpAt(t, dirFD, path, func(root *fs.Dirent, d *fs.Dirent, name string) error {
return fileOpAt(t, dirFD, path, func(root *fs.Dirent, d *fs.Dirent, name string, _ uint) error {
if !fs.IsDir(d.Inode.StableAttr) {
return syserror.ENOTDIR
}
@ -304,7 +304,7 @@ func createAt(t *kernel.Task, dirFD kdefs.FD, addr usermem.Addr, flags uint, mod
return 0, syserror.ENOENT
}
err = fileOpAt(t, dirFD, path, func(root *fs.Dirent, d *fs.Dirent, name string) error {
err = fileOpAt(t, dirFD, path, func(root *fs.Dirent, d *fs.Dirent, name string, remainingTraversals uint) error {
if !fs.IsDir(d.Inode.StableAttr) {
return syserror.ENOTDIR
}
@ -314,7 +314,6 @@ func createAt(t *kernel.Task, dirFD kdefs.FD, addr usermem.Addr, flags uint, mod
fileFlags.LargeFile = true
// Does this file exist already?
remainingTraversals := uint(linux.MaxSymlinkTraversals)
targetDirent, err := t.MountNamespace().FindInode(t, root, d, name, &remainingTraversals)
var newFile *fs.File
switch err {
@ -458,7 +457,7 @@ func accessAt(t *kernel.Task, dirFD kdefs.FD, addr usermem.Addr, resolve bool, m
return syserror.EINVAL
}
return fileOpOn(t, dirFD, path, resolve, func(root *fs.Dirent, d *fs.Dirent) error {
return fileOpOn(t, dirFD, path, resolve, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
// access(2) and faccessat(2) check permissions using real
// UID/GID, not effective UID/GID.
//
@ -626,7 +625,7 @@ func Chroot(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
return 0, nil, err
}
return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent) error {
return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
// Is it a directory?
if !fs.IsDir(d.Inode.StableAttr) {
return syserror.ENOTDIR
@ -651,7 +650,7 @@ func Chdir(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
return 0, nil, err
}
return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent) error {
return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
// Is it a directory?
if !fs.IsDir(d.Inode.StableAttr) {
return syserror.ENOTDIR
@ -1017,7 +1016,7 @@ func mkdirAt(t *kernel.Task, dirFD kdefs.FD, addr usermem.Addr, mode linux.FileM
return err
}
return fileOpAt(t, dirFD, path, func(root *fs.Dirent, d *fs.Dirent, name string) error {
return fileOpAt(t, dirFD, path, func(root *fs.Dirent, d *fs.Dirent, name string, _ uint) error {
if !fs.IsDir(d.Inode.StableAttr) {
return syserror.ENOTDIR
}
@ -1074,7 +1073,7 @@ func rmdirAt(t *kernel.Task, dirFD kdefs.FD, addr usermem.Addr) error {
return syserror.EBUSY
}
return fileOpAt(t, dirFD, path, func(root *fs.Dirent, d *fs.Dirent, name string) error {
return fileOpAt(t, dirFD, path, func(root *fs.Dirent, d *fs.Dirent, name string, _ uint) error {
if !fs.IsDir(d.Inode.StableAttr) {
return syserror.ENOTDIR
}
@ -1122,7 +1121,7 @@ func symlinkAt(t *kernel.Task, dirFD kdefs.FD, newAddr usermem.Addr, oldAddr use
return syserror.ENOENT
}
return fileOpAt(t, dirFD, newPath, func(root *fs.Dirent, d *fs.Dirent, name string) error {
return fileOpAt(t, dirFD, newPath, func(root *fs.Dirent, d *fs.Dirent, name string, _ uint) error {
if !fs.IsDir(d.Inode.StableAttr) {
return syserror.ENOTDIR
}
@ -1212,7 +1211,7 @@ func linkAt(t *kernel.Task, oldDirFD kdefs.FD, oldAddr usermem.Addr, newDirFD kd
}
// Resolve the target directory.
return fileOpAt(t, newDirFD, newPath, func(root *fs.Dirent, newParent *fs.Dirent, newName string) error {
return fileOpAt(t, newDirFD, newPath, func(root *fs.Dirent, newParent *fs.Dirent, newName string, _ uint) error {
if !fs.IsDir(newParent.Inode.StableAttr) {
return syserror.ENOTDIR
}
@ -1227,13 +1226,13 @@ func linkAt(t *kernel.Task, oldDirFD kdefs.FD, oldAddr usermem.Addr, newDirFD kd
// Resolve oldDirFD and oldAddr to a dirent. The "resolve" argument
// only applies to this name.
return fileOpOn(t, oldDirFD, oldPath, resolve, func(root *fs.Dirent, target *fs.Dirent) error {
return fileOpOn(t, oldDirFD, oldPath, resolve, func(root *fs.Dirent, target *fs.Dirent, _ uint) error {
if err := mayLinkAt(t, target.Inode); err != nil {
return err
}
// Next resolve newDirFD and newAddr to the parent dirent and name.
return fileOpAt(t, newDirFD, newPath, func(root *fs.Dirent, newParent *fs.Dirent, newName string) error {
return fileOpAt(t, newDirFD, newPath, func(root *fs.Dirent, newParent *fs.Dirent, newName string, _ uint) error {
if !fs.IsDir(newParent.Inode.StableAttr) {
return syserror.ENOTDIR
}
@ -1300,7 +1299,7 @@ func readlinkAt(t *kernel.Task, dirFD kdefs.FD, addr usermem.Addr, bufAddr userm
return 0, syserror.ENOENT
}
err = fileOpOn(t, dirFD, path, false /* resolve */, func(root *fs.Dirent, d *fs.Dirent) error {
err = fileOpOn(t, dirFD, path, false /* resolve */, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
// Check for Read permission.
if err := d.Inode.CheckPermission(t, fs.PermMask{Read: true}); err != nil {
return err
@ -1359,7 +1358,7 @@ func unlinkAt(t *kernel.Task, dirFD kdefs.FD, addr usermem.Addr) error {
return syserror.ENOENT
}
return fileOpAt(t, dirFD, path, func(root *fs.Dirent, d *fs.Dirent, name string) error {
return fileOpAt(t, dirFD, path, func(root *fs.Dirent, d *fs.Dirent, name string, _ uint) error {
if !fs.IsDir(d.Inode.StableAttr) {
return syserror.ENOTDIR
}
@ -1414,7 +1413,7 @@ func Truncate(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
return 0, nil, syserror.EFBIG
}
return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent) error {
return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
if fs.IsDir(d.Inode.StableAttr) {
return syserror.EISDIR
}
@ -1576,7 +1575,7 @@ func chownAt(t *kernel.Task, fd kdefs.FD, addr usermem.Addr, resolve, allowEmpty
return chown(t, file.Dirent, uid, gid)
}
return fileOpOn(t, fd, path, resolve, func(root *fs.Dirent, d *fs.Dirent) error {
return fileOpOn(t, fd, path, resolve, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
return chown(t, d, uid, gid)
})
}
@ -1652,7 +1651,7 @@ func chmodAt(t *kernel.Task, fd kdefs.FD, addr usermem.Addr, mode linux.FileMode
return err
}
return fileOpOn(t, fd, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent) error {
return fileOpOn(t, fd, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
return chmod(t, d, mode)
})
}
@ -1698,7 +1697,7 @@ func defaultSetToSystemTimeSpec() fs.TimeSpec {
}
func utimes(t *kernel.Task, dirFD kdefs.FD, addr usermem.Addr, ts fs.TimeSpec, resolve bool) error {
setTimestamp := func(root *fs.Dirent, d *fs.Dirent) error {
setTimestamp := func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
// Does the task own the file?
if !d.Inode.CheckOwnership(t) {
// Trying to set a specific time? Must be owner.
@ -1739,7 +1738,7 @@ func utimes(t *kernel.Task, dirFD kdefs.FD, addr usermem.Addr, ts fs.TimeSpec, r
root := t.FSContext().RootDirectory()
defer root.DecRef()
return setTimestamp(root, f.Dirent)
return setTimestamp(root, f.Dirent, linux.MaxSymlinkTraversals)
}
path, _, err := copyInPath(t, addr, false /* allowEmpty */)
@ -1867,7 +1866,7 @@ func renameAt(t *kernel.Task, oldDirFD kdefs.FD, oldAddr usermem.Addr, newDirFD
return err
}
return fileOpAt(t, oldDirFD, oldPath, func(root *fs.Dirent, oldParent *fs.Dirent, oldName string) error {
return fileOpAt(t, oldDirFD, oldPath, func(root *fs.Dirent, oldParent *fs.Dirent, oldName string, _ uint) error {
if !fs.IsDir(oldParent.Inode.StableAttr) {
return syserror.ENOTDIR
}
@ -1879,7 +1878,7 @@ func renameAt(t *kernel.Task, oldDirFD kdefs.FD, oldAddr usermem.Addr, newDirFD
return syserror.EBUSY
}
return fileOpAt(t, newDirFD, newPath, func(root *fs.Dirent, newParent *fs.Dirent, newName string) error {
return fileOpAt(t, newDirFD, newPath, func(root *fs.Dirent, newParent *fs.Dirent, newName string, _ uint) error {
if !fs.IsDir(newParent.Inode.StableAttr) {
return syserror.ENOTDIR
}

2
pkg/sentry/syscalls/linux/sys_inotify.go
View File

@ -107,7 +107,7 @@ func InotifyAddWatch(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kern
return 0, nil, err
}
err = fileOpOn(t, linux.AT_FDCWD, path, resolve, func(root *fs.Dirent, dirent *fs.Dirent) error {
err = fileOpOn(t, linux.AT_FDCWD, path, resolve, func(root *fs.Dirent, dirent *fs.Dirent, _ uint) error {
// "IN_ONLYDIR: Only watch pathname if it is a directory." -- inotify(7)
if onlyDir := mask&linux.IN_ONLYDIR != 0; onlyDir && !fs.IsDir(dirent.Inode.StableAttr) {
return syscall.ENOTDIR

4
pkg/sentry/syscalls/linux/sys_mount.go
View File

@ -109,7 +109,7 @@ func Mount(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
return 0, nil, syserror.EINVAL
}
return 0, nil, fileOpOn(t, linux.AT_FDCWD, targetPath, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent) error {
return 0, nil, fileOpOn(t, linux.AT_FDCWD, targetPath, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
return t.MountNamespace().Mount(t, d, rootInode)
})
}
@ -140,7 +140,7 @@ func Umount2(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysca
resolve := flags&linux.UMOUNT_NOFOLLOW != linux.UMOUNT_NOFOLLOW
detachOnly := flags&linux.MNT_DETACH == linux.MNT_DETACH
return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, resolve, func(root *fs.Dirent, d *fs.Dirent) error {
return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, resolve, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
return t.MountNamespace().Unmount(t, d, detachOnly)
})
}

8
pkg/sentry/syscalls/linux/sys_stat.go
View File

@ -35,7 +35,7 @@ func Stat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallC
return 0, nil, err
}
return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent) error {
return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
return stat(t, d, dirPath, statAddr)
})
}
@ -67,7 +67,7 @@ func Fstatat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysca
// then we must resolve the final component.
resolve := dirPath || flags&linux.AT_SYMLINK_NOFOLLOW == 0
return 0, nil, fileOpOn(t, fd, path, resolve, func(root *fs.Dirent, d *fs.Dirent) error {
return 0, nil, fileOpOn(t, fd, path, resolve, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
return stat(t, d, dirPath, statAddr)
})
}
@ -86,7 +86,7 @@ func Lstat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
// want to resolve the final component.
resolve := dirPath
return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, resolve, func(root *fs.Dirent, d *fs.Dirent) error {
return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, resolve, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
return stat(t, d, dirPath, statAddr)
})
}
@ -204,7 +204,7 @@ func Statfs(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
return 0, nil, err
}
return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent) error {
return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
return statfsImpl(t, d, statfsAddr)
})
}