From 0ca0d8e0110d284120497569dca1b85d3ec227fe Mon Sep 17 00:00:00 2001
From: Ayush Ranjan <ayushranjan@google.com>
Date: Wed, 2 Sep 2020 15:39:51 -0700
Subject: [vfs] Fix error handling in overlayfs OpenAt.
Updates #1199
PiperOrigin-RevId: 329802274
---
pkg/sentry/fsimpl/overlay/filesystem.go | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
(limited to 'pkg/sentry/fsimpl/overlay')
diff --git a/pkg/sentry/fsimpl/overlay/filesystem.go b/pkg/sentry/fsimpl/overlay/filesystem.go
index e720bfb0b..63df86481 100644
--- a/pkg/sentry/fsimpl/overlay/filesystem.go
+++ b/pkg/sentry/fsimpl/overlay/filesystem.go
@@ -743,6 +743,9 @@ func (fs *filesystem) OpenAt(ctx context.Context, rp *vfs.ResolvingPath, opts vf
start := rp.Start().Impl().(*dentry)
if rp.Done() {
+ if mayCreate && rp.MustBeDir() {
+ return nil, syserror.EISDIR
+ }
if mustCreate {
return nil, syserror.EEXIST
}
@@ -766,6 +769,10 @@ afterTrailingSymlink:
if err := parent.checkPermissions(rp.Credentials(), vfs.MayExec); err != nil {
return nil, err
}
+ // Reject attempts to open directories with O_CREAT.
+ if mayCreate && rp.MustBeDir() {
+ return nil, syserror.EISDIR
+ }
// Determine whether or not we need to create a file.
parent.dirMu.Lock()
child, err := fs.stepLocked(ctx, rp, parent, false /* mayFollowSymlinks */, &ds)
@@ -774,12 +781,11 @@ afterTrailingSymlink:
parent.dirMu.Unlock()
return fd, err
}
+ parent.dirMu.Unlock()
if err != nil {
- parent.dirMu.Unlock()
return nil, err
}
// Open existing child or follow symlink.
- parent.dirMu.Unlock()
if mustCreate {
return nil, syserror.EEXIST
}
@@ -794,6 +800,9 @@ afterTrailingSymlink:
start = parent
goto afterTrailingSymlink
}
+ if rp.MustBeDir() && !child.isDir() {
+ return nil, syserror.ENOTDIR
+ }
if mayWrite {
if err := child.copyUpLocked(ctx); err != nil {
return nil, err
--
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