diff options
Diffstat (limited to 'pkg/sentry/fsimpl/gofer/filesystem.go')
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/filesystem.go | 35 |
1 files changed, 32 insertions, 3 deletions
diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go index 51082359d..7bcc99b29 100644 --- a/pkg/sentry/fsimpl/gofer/filesystem.go +++ b/pkg/sentry/fsimpl/gofer/filesystem.go @@ -869,11 +869,22 @@ func (d *dentry) openLocked(ctx context.Context, rp *vfs.ResolvingPath, opts *vf if err := d.checkPermissions(rp.Credentials(), ats); err != nil { return nil, err } + + trunc := opts.Flags&linux.O_TRUNC != 0 && d.fileType() == linux.S_IFREG + if trunc { + // Lock metadataMu *while* we open a regular file with O_TRUNC because + // open(2) will change the file size on server. + d.metadataMu.Lock() + defer d.metadataMu.Unlock() + } + + var vfd *vfs.FileDescription + var err error mnt := rp.Mount() switch d.fileType() { case linux.S_IFREG: if !d.fs.opts.regularFilesUseSpecialFileFD { - if err := d.ensureSharedHandle(ctx, ats&vfs.MayRead != 0, ats&vfs.MayWrite != 0, opts.Flags&linux.O_TRUNC != 0); err != nil { + if err := d.ensureSharedHandle(ctx, ats&vfs.MayRead != 0, ats&vfs.MayWrite != 0, trunc); err != nil { return nil, err } fd := ®ularFileFD{} @@ -883,7 +894,7 @@ func (d *dentry) openLocked(ctx context.Context, rp *vfs.ResolvingPath, opts *vf }); err != nil { return nil, err } - return &fd.vfsfd, nil + vfd = &fd.vfsfd } case linux.S_IFDIR: // Can't open directories with O_CREAT. @@ -923,7 +934,25 @@ func (d *dentry) openLocked(ctx context.Context, rp *vfs.ResolvingPath, opts *vf return d.pipe.Open(ctx, mnt, &d.vfsd, opts.Flags, &d.locks) } } - return d.openSpecialFileLocked(ctx, mnt, opts) + + if vfd == nil { + if vfd, err = d.openSpecialFileLocked(ctx, mnt, opts); err != nil { + return nil, err + } + } + + if trunc { + // If no errors occured so far then update file size in memory. This + // step is required even if !d.cachedMetadataAuthoritative() because + // d.mappings has to be updated. + // d.metadataMu has already been acquired if trunc == true. + d.updateFileSizeLocked(0) + + if d.cachedMetadataAuthoritative() { + d.touchCMtimeLocked() + } + } + return vfd, err } func (d *dentry) connectSocketLocked(ctx context.Context, opts *vfs.OpenOptions) (*vfs.FileDescription, error) { |