[Spice-devel] [vdagent-win PATCH] Avoid to use names with invalid characters.

[Frediano Ziglio]

> 
> On Fri, Sep 02, 2016 at 04:43:53PM +0100, Frediano Ziglio wrote:
> > Check if filename contains invalid characters.
> 
> Can you be more specific here about "invalid"? My guess is that these
> are characters which are invalid in an NTFS filesystem.
> 

Some characters are reserved and should not be used in Windows
independently by the file system used.

> > Also this avoid to use paths in the filename which could lead to some
> > nasty hacks (like names like "..\hack.txt").
> > 
> > Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
> > ---
> >  vdagent/file_xfer.cpp | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/vdagent/file_xfer.cpp b/vdagent/file_xfer.cpp
> > index 0e90ebe..2072277 100644
> > --- a/vdagent/file_xfer.cpp
> > +++ b/vdagent/file_xfer.cpp
> > @@ -65,6 +65,10 @@ void FileXfer::handle_start(VDAgentFileXferStartMessage*
> > start,
> >          return;
> >      }
> >      vd_printf("%u %s (%" PRIu64 ")", start->id, file_name, file_size);
> > +    if (strcspn(file_name, "<>:\"/\\|?*") != strlen(file_name)) {
> 
> You could add ^ as well which is invalid on FAT. Apparently we could
> check for trailing space or colon too.
> 

Colon is in the list. It's used to separate filename from stream name and can
be used to create hidden streams. Also is used for drive separator (A:) or device names (NUL:).

/ and \ are reserved for components (directory, filename, drive, share, server) separators.

* and ? are globs (globs on Windows are supported by different APIs too).

Other are reserved for shell usage (<, > and |).

Space at the end are just misleading but supported.

^, & and ; are (strangely) accepted (at least by NTFS).

> 
> 
> Christophe
> 

The more worrying are the path separators.

Frediano