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Diffstat (limited to 'pkg/sentry/fs/dirent.go')
-rw-r--r--pkg/sentry/fs/dirent.go164
1 files changed, 18 insertions, 146 deletions
diff --git a/pkg/sentry/fs/dirent.go b/pkg/sentry/fs/dirent.go
index acab0411a..65be12175 100644
--- a/pkg/sentry/fs/dirent.go
+++ b/pkg/sentry/fs/dirent.go
@@ -17,7 +17,6 @@ package fs
import (
"fmt"
"path"
- "sort"
"sync/atomic"
"syscall"
@@ -121,9 +120,6 @@ type Dirent struct {
// deleted may be set atomically when removed.
deleted int32
- // frozen indicates this entry can't walk to unknown nodes.
- frozen bool
-
// mounted is true if Dirent is a mount point, similar to include/linux/dcache.h:DCACHE_MOUNTED.
mounted bool
@@ -253,8 +249,7 @@ func (d *Dirent) IsNegative() bool {
return d.Inode == nil
}
-// hashChild will hash child into the children list of its new parent d, carrying over
-// any "frozen" state from d.
+// hashChild will hash child into the children list of its new parent d.
//
// Returns (*WeakRef, true) if hashing child caused a Dirent to be unhashed. The caller must
// validate the returned unhashed weak reference. Common cases:
@@ -282,9 +277,6 @@ func (d *Dirent) hashChild(child *Dirent) (*refs.WeakRef, bool) {
d.IncRef()
}
- // Carry over parent's frozen state.
- child.frozen = d.frozen
-
return d.hashChildParentSet(child)
}
@@ -320,9 +312,9 @@ func (d *Dirent) SyncAll(ctx context.Context) {
// There is nothing to sync for a read-only filesystem.
if !d.Inode.MountSource.Flags.ReadOnly {
- // FIXME(b/34856369): This should be a mount traversal, not a
- // Dirent traversal, because some Inodes that need to be synced
- // may no longer be reachable by name (after sys_unlink).
+ // NOTE(b/34856369): This should be a mount traversal, not a Dirent
+ // traversal, because some Inodes that need to be synced may no longer
+ // be reachable by name (after sys_unlink).
//
// Write out metadata, dirty page cached pages, and sync disk/remote
// caches.
@@ -400,38 +392,6 @@ func (d *Dirent) MountRoot() *Dirent {
return mountRoot
}
-// Freeze prevents this dirent from walking to more nodes. Freeze is applied
-// recursively to all children.
-//
-// If this particular Dirent represents a Virtual node, then Walks and Creates
-// may proceed as before.
-//
-// Freeze can only be called before the application starts running, otherwise
-// the root it might be out of sync with the application root if modified by
-// sys_chroot.
-func (d *Dirent) Freeze() {
- d.mu.Lock()
- defer d.mu.Unlock()
- if d.frozen {
- // Already frozen.
- return
- }
- d.frozen = true
-
- // Take a reference when freezing.
- for _, w := range d.children {
- if child := w.Get(); child != nil {
- // NOTE: We would normally drop the reference here. But
- // instead we're hanging on to it.
- ch := child.(*Dirent)
- ch.Freeze()
- }
- }
-
- // Drop all expired weak references.
- d.flush()
-}
-
// descendantOf returns true if the receiver dirent is equal to, or a
// descendant of, the argument dirent.
//
@@ -524,11 +484,6 @@ func (d *Dirent) walk(ctx context.Context, root *Dirent, name string, walkMayUnl
w.Drop()
}
- // Are we allowed to do the lookup?
- if d.frozen && !d.Inode.IsVirtual() {
- return nil, syscall.ENOENT
- }
-
// Slow path: load the InodeOperations into memory. Since this is a hot path and the lookup may be
// expensive, if possible release the lock and re-acquire it.
if walkMayUnlock {
@@ -659,11 +614,6 @@ func (d *Dirent) Create(ctx context.Context, root *Dirent, name string, flags Fi
return nil, syscall.EEXIST
}
- // Are we frozen?
- if d.frozen && !d.Inode.IsVirtual() {
- return nil, syscall.ENOENT
- }
-
// Try the create. We need to trust the file system to return EEXIST (or something
// that will translate to EEXIST) if name already exists.
file, err := d.Inode.Create(ctx, d, name, flags, perms)
@@ -727,11 +677,6 @@ func (d *Dirent) genericCreate(ctx context.Context, root *Dirent, name string, c
return syscall.EEXIST
}
- // Are we frozen?
- if d.frozen && !d.Inode.IsVirtual() {
- return syscall.ENOENT
- }
-
// Remove any negative Dirent. We've already asserted above with d.exists
// that the only thing remaining here can be a negative Dirent.
if w, ok := d.children[name]; ok {
@@ -862,49 +807,6 @@ func (d *Dirent) GetDotAttrs(root *Dirent) (DentAttr, DentAttr) {
return dot, dot
}
-// readdirFrozen returns readdir results based solely on the frozen children.
-func (d *Dirent) readdirFrozen(root *Dirent, offset int64, dirCtx *DirCtx) (int64, error) {
- // Collect attrs for "." and "..".
- attrs := make(map[string]DentAttr)
- names := []string{".", ".."}
- attrs["."], attrs[".."] = d.GetDotAttrs(root)
-
- // Get info from all children.
- d.mu.Lock()
- defer d.mu.Unlock()
- for name, w := range d.children {
- if child := w.Get(); child != nil {
- defer child.DecRef()
-
- // Skip negative children.
- if child.(*Dirent).IsNegative() {
- continue
- }
-
- sattr := child.(*Dirent).Inode.StableAttr
- attrs[name] = DentAttr{
- Type: sattr.Type,
- InodeID: sattr.InodeID,
- }
- names = append(names, name)
- }
- }
-
- sort.Strings(names)
-
- if int(offset) >= len(names) {
- return offset, nil
- }
- names = names[int(offset):]
- for _, name := range names {
- if err := dirCtx.DirEmit(name, attrs[name]); err != nil {
- return offset, err
- }
- offset++
- }
- return offset, nil
-}
-
// DirIterator is an open directory containing directory entries that can be read.
type DirIterator interface {
// IterateDir emits directory entries by calling dirCtx.EmitDir, beginning
@@ -964,10 +866,6 @@ func direntReaddir(ctx context.Context, d *Dirent, it DirIterator, root *Dirent,
return offset, nil
}
- if d.frozen {
- return d.readdirFrozen(root, offset, dirCtx)
- }
-
// Collect attrs for "." and "..".
dot, dotdot := d.GetDotAttrs(root)
@@ -1068,11 +966,6 @@ func (d *Dirent) mount(ctx context.Context, inode *Inode) (newChild *Dirent, err
return nil, syserror.EINVAL
}
- // Are we frozen?
- if d.parent.frozen && !d.parent.Inode.IsVirtual() {
- return nil, syserror.ENOENT
- }
-
// Dirent that'll replace d.
//
// Note that NewDirent returns with one reference taken; the reference
@@ -1101,11 +994,6 @@ func (d *Dirent) unmount(ctx context.Context, replacement *Dirent) error {
return syserror.ENOENT
}
- // Are we frozen?
- if d.parent.frozen && !d.parent.Inode.IsVirtual() {
- return syserror.ENOENT
- }
-
// Remount our former child in its place.
//
// As replacement used to be our child, it must already have the right
@@ -1135,11 +1023,6 @@ func (d *Dirent) Remove(ctx context.Context, root *Dirent, name string, dirPath
unlock := d.lockDirectory()
defer unlock()
- // Are we frozen?
- if d.frozen && !d.Inode.IsVirtual() {
- return syscall.ENOENT
- }
-
// Try to walk to the node.
child, err := d.walk(ctx, root, name, false /* may unlock */)
if err != nil {
@@ -1201,11 +1084,6 @@ func (d *Dirent) RemoveDirectory(ctx context.Context, root *Dirent, name string)
unlock := d.lockDirectory()
defer unlock()
- // Are we frozen?
- if d.frozen && !d.Inode.IsVirtual() {
- return syscall.ENOENT
- }
-
// Check for dots.
if name == "." {
// Rejected as the last component by rmdir(2).
@@ -1438,8 +1316,8 @@ func lockForRename(oldParent *Dirent, oldName string, newParent *Dirent, newName
}, nil
}
-func checkSticky(ctx context.Context, dir *Dirent, victim *Dirent) error {
- uattr, err := dir.Inode.UnstableAttr(ctx)
+func (d *Dirent) checkSticky(ctx context.Context, victim *Dirent) error {
+ uattr, err := d.Inode.UnstableAttr(ctx)
if err != nil {
return syserror.EPERM
}
@@ -1465,30 +1343,33 @@ func checkSticky(ctx context.Context, dir *Dirent, victim *Dirent) error {
return syserror.EPERM
}
-// MayDelete determines whether `name`, a child of `dir`, can be deleted or
+// MayDelete determines whether `name`, a child of `d`, can be deleted or
// renamed by `ctx`.
//
// Compare Linux kernel fs/namei.c:may_delete.
-func MayDelete(ctx context.Context, root, dir *Dirent, name string) error {
- if err := dir.Inode.CheckPermission(ctx, PermMask{Write: true, Execute: true}); err != nil {
+func (d *Dirent) MayDelete(ctx context.Context, root *Dirent, name string) error {
+ if err := d.Inode.CheckPermission(ctx, PermMask{Write: true, Execute: true}); err != nil {
return err
}
- victim, err := dir.Walk(ctx, root, name)
+ unlock := d.lockDirectory()
+ defer unlock()
+
+ victim, err := d.walk(ctx, root, name, true /* may unlock */)
if err != nil {
return err
}
defer victim.DecRef()
- return mayDelete(ctx, dir, victim)
+ return d.mayDelete(ctx, victim)
}
// mayDelete determines whether `victim`, a child of `dir`, can be deleted or
// renamed by `ctx`.
//
// Preconditions: `dir` is writable and executable by `ctx`.
-func mayDelete(ctx context.Context, dir, victim *Dirent) error {
- if err := checkSticky(ctx, dir, victim); err != nil {
+func (d *Dirent) mayDelete(ctx context.Context, victim *Dirent) error {
+ if err := d.checkSticky(ctx, victim); err != nil {
return err
}
@@ -1516,15 +1397,6 @@ func Rename(ctx context.Context, root *Dirent, oldParent *Dirent, oldName string
return err
}
- // Are we frozen?
- // TODO(jamieliu): Is this the right errno?
- if oldParent.frozen && !oldParent.Inode.IsVirtual() {
- return syscall.ENOENT
- }
- if newParent.frozen && !newParent.Inode.IsVirtual() {
- return syscall.ENOENT
- }
-
// Do we have general permission to remove from oldParent and
// create/replace in newParent?
if err := oldParent.Inode.CheckPermission(ctx, PermMask{Write: true, Execute: true}); err != nil {
@@ -1542,7 +1414,7 @@ func Rename(ctx context.Context, root *Dirent, oldParent *Dirent, oldName string
defer renamed.DecRef()
// Check that the renamed dirent is deletable.
- if err := mayDelete(ctx, oldParent, renamed); err != nil {
+ if err := oldParent.mayDelete(ctx, renamed); err != nil {
return err
}
@@ -1580,7 +1452,7 @@ func Rename(ctx context.Context, root *Dirent, oldParent *Dirent, oldName string
// across the Rename, so must call DecRef manually (no defer).
// Check that we can delete replaced.
- if err := mayDelete(ctx, newParent, replaced); err != nil {
+ if err := newParent.mayDelete(ctx, replaced); err != nil {
replaced.DecRef()
return err
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-08 02:57:54 +0000