On Mon, Apr 22, 2024 at 12:58:10PM -0500, Eric Blake wrote:
> On Sun, Apr 21, 2024 at 08:15:42PM +0100, Richard W.M. Jones wrote:
> > The plugin/filter short name detection is very liberal, reserving only
> > '.' and '/'. Thus, at least in theory, short plugin names containing
> > almost arbitrary symbols and characters are permitted.
> >
> > Backslash ought to have been reserved when we added Windows support.
> >
> > We should probably reserve more characters, but in this commit I only
> > reserve:
> >
> > * backslash (ie. directory separator on Windows)
> > * ':' and ';' (common path separators)
> > * '=' (used in nbdkit parameters)
>
> Oh, I reviewed v1 before you added '=' to the reject list in v2.
>
> > * space and comma (commonly used to separate lists)
> > * non-printable ASCII characters
> >
> > Also DIR_SEPARATOR_STR, but that's likely to be already covered by the
> > other tests so probably does nothing here.
> >
> > This commit is mainly about tightening up corner cases with possible
> > security implications, for example if you managed to trick a program
> > to invoke 'nbdkit "plugin param"' that might have an ambiguous parsing
> > that you could use to your advantage. It should have no effect on
> > normal, non-adversarial usage.
> > ---
> > server/options.h | 18 +++++++++++++++++-
> > 1 file changed, 17 insertions(+), 1 deletion(-)
> >
>
> > +
> > + for (i = 0; i < n; ++i) {
> > + switch (filename[i]) {
> > + case '\0'...31: case 127: /* non-printable ASCII */
>
> The comment about ranged case label is still present (I'm okay whether
> you keep it in or explode it to long-hand).
I'll change it to:
+ /* non-printable ASCII */
+ case 127:
+ return false;
+ default:
+ if ((unsigned)filename[i] <= 31)
+ return false;
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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