diff options
| -rwxr-xr-x | pkg/sentry/fsimpl/gofer/filesystem.go | 35 | ||||
| -rwxr-xr-x | pkg/sentry/fsimpl/gofer/special_file.go | 28 |
2 files changed, 39 insertions, 24 deletions
diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go index 7ca0cf3f4..7f2181216 100755 --- a/pkg/sentry/fsimpl/gofer/filesystem.go +++ b/pkg/sentry/fsimpl/gofer/filesystem.go @@ -877,10 +877,15 @@ func (d *dentry) openSpecialFileLocked(ctx context.Context, mnt *vfs.Mount, opts if err != nil { return nil, err } + seekable := d.fileType() == linux.S_IFREG fd := &specialFileFD{ - handle: h, + handle: h, + seekable: seekable, } - if err := fd.vfsfd.Init(fd, opts.Flags, mnt, &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil { + if err := fd.vfsfd.Init(fd, opts.Flags, mnt, &d.vfsd, &vfs.FileDescriptionOptions{ + DenyPRead: !seekable, + DenyPWrite: !seekable, + }); err != nil { h.close(ctx) return nil, err } @@ -911,7 +916,11 @@ func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.Resolving } creds := rp.Credentials() name := rp.Component() - fdobj, openFile, createQID, _, err := dirfile.create(ctx, name, (p9.OpenFlags)(opts.Flags), (p9.FileMode)(opts.Mode), (p9.UID)(creds.EffectiveKUID), (p9.GID)(creds.EffectiveKGID)) + // Filter file creation flags and O_LARGEFILE out; the create RPC already + // has the semantics of O_CREAT|O_EXCL, while some servers will choke on + // O_LARGEFILE. + createFlags := p9.OpenFlags(opts.Flags &^ (linux.O_CREAT | linux.O_EXCL | linux.O_NOCTTY | linux.O_TRUNC | linux.O_LARGEFILE)) + fdobj, openFile, createQID, _, err := dirfile.create(ctx, name, createFlags, (p9.FileMode)(opts.Mode), (p9.UID)(creds.EffectiveKUID), (p9.GID)(creds.EffectiveKGID)) if err != nil { dirfile.close(ctx) return nil, err @@ -919,7 +928,7 @@ func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.Resolving // Then we need to walk to the file we just created to get a non-open fid // representing it, and to get its metadata. This must use d.file since, as // explained above, dirfile was invalidated by dirfile.Create(). - walkQID, nonOpenFile, attrMask, attr, err := d.file.walkGetAttrOne(ctx, name) + _, nonOpenFile, attrMask, attr, err := d.file.walkGetAttrOne(ctx, name) if err != nil { openFile.close(ctx) if fdobj != nil { @@ -927,17 +936,6 @@ func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.Resolving } return nil, err } - // Sanity-check that we walked to the file we created. - if createQID.Path != walkQID.Path { - // Probably due to concurrent remote filesystem mutation? - ctx.Warningf("gofer.dentry.createAndOpenChildLocked: created file has QID %v before walk, QID %v after (interop=%v)", createQID, walkQID, d.fs.opts.interop) - nonOpenFile.close(ctx) - openFile.close(ctx) - if fdobj != nil { - fdobj.Close() - } - return nil, syserror.EAGAIN - } // Construct the new dentry. child, err := d.fs.newDentry(ctx, nonOpenFile, createQID, attrMask, &attr) @@ -983,16 +981,21 @@ func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.Resolving } childVFSFD = &fd.vfsfd } else { + seekable := child.fileType() == linux.S_IFREG fd := &specialFileFD{ handle: handle{ file: openFile, fd: -1, }, + seekable: seekable, } if fdobj != nil { fd.handle.fd = int32(fdobj.Release()) } - if err := fd.vfsfd.Init(fd, opts.Flags, mnt, &child.vfsd, &vfs.FileDescriptionOptions{}); err != nil { + if err := fd.vfsfd.Init(fd, opts.Flags, mnt, &child.vfsd, &vfs.FileDescriptionOptions{ + DenyPRead: !seekable, + DenyPWrite: !seekable, + }); err != nil { fd.handle.close(ctx) return nil, err } diff --git a/pkg/sentry/fsimpl/gofer/special_file.go b/pkg/sentry/fsimpl/gofer/special_file.go index 507e0e276..a464e6a94 100755 --- a/pkg/sentry/fsimpl/gofer/special_file.go +++ b/pkg/sentry/fsimpl/gofer/special_file.go @@ -33,13 +33,14 @@ import ( type specialFileFD struct { fileDescription - // handle is immutable. + // handle is used for file I/O. handle is immutable. handle handle - // off is the file offset. off is protected by mu. (POSIX 2.9.7 only - // requires operations using the file offset to be atomic for regular files - // and symlinks; however, since specialFileFD may be used for regular - // files, we apply this atomicity unconditionally.) + // seekable is true if this file description represents a file for which + // file offset is significant, i.e. a regular file. seekable is immutable. + seekable bool + + // If seekable is true, off is the file offset. off is protected by mu. mu sync.Mutex off int64 } @@ -63,7 +64,7 @@ func (fd *specialFileFD) OnClose(ctx context.Context) error { // PRead implements vfs.FileDescriptionImpl.PRead. func (fd *specialFileFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) { - if offset < 0 { + if fd.seekable && offset < 0 { return 0, syserror.EINVAL } if opts.Flags != 0 { @@ -91,6 +92,10 @@ func (fd *specialFileFD) PRead(ctx context.Context, dst usermem.IOSequence, offs // Read implements vfs.FileDescriptionImpl.Read. func (fd *specialFileFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) { + if !fd.seekable { + return fd.PRead(ctx, dst, -1, opts) + } + fd.mu.Lock() n, err := fd.PRead(ctx, dst, fd.off, opts) fd.off += n @@ -100,14 +105,14 @@ func (fd *specialFileFD) Read(ctx context.Context, dst usermem.IOSequence, opts // PWrite implements vfs.FileDescriptionImpl.PWrite. func (fd *specialFileFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) { - if offset < 0 { + if fd.seekable && offset < 0 { return 0, syserror.EINVAL } if opts.Flags != 0 { return 0, syserror.EOPNOTSUPP } - if fd.dentry().fileType() == linux.S_IFREG { + if fd.seekable { limit, err := vfs.CheckLimit(ctx, offset, src.NumBytes()) if err != nil { return 0, err @@ -130,6 +135,10 @@ func (fd *specialFileFD) PWrite(ctx context.Context, src usermem.IOSequence, off // Write implements vfs.FileDescriptionImpl.Write. func (fd *specialFileFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) { + if !fd.seekable { + return fd.PWrite(ctx, src, -1, opts) + } + fd.mu.Lock() n, err := fd.PWrite(ctx, src, fd.off, opts) fd.off += n @@ -139,6 +148,9 @@ func (fd *specialFileFD) Write(ctx context.Context, src usermem.IOSequence, opts // Seek implements vfs.FileDescriptionImpl.Seek. func (fd *specialFileFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) { + if !fd.seekable { + return 0, syserror.ESPIPE + } fd.mu.Lock() defer fd.mu.Unlock() switch whence { |