Re: [PATCH nft] evaluate: bogus error when refering to existing non-base chain

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Tue, Jul 16, 2019 at 08:12:53PM +0200, Pablo Neira Ayuso wrote:
> On Tue, Jul 16, 2019 at 08:00:04PM +0200, Florian Westphal wrote:
> > Fernando Fernandez Mancera <ffmancera@riseup.net> wrote:
> > > El 16 de julio de 2019 18:47:11 CEST, Phil Sutter <phil@nwl.cc> escribió:
> > > >Hi Pablo,
> > > >
> > > >On Tue, Jul 16, 2019 at 01:51:20PM +0200, Pablo Neira Ayuso wrote:
> > > >[...]
> > > >> diff --git a/src/evaluate.c b/src/evaluate.c
> > > >> index f95f42e1067a..cd566e856a11 100644
> > > >> --- a/src/evaluate.c
> > > >> +++ b/src/evaluate.c
> > > >> @@ -1984,17 +1984,9 @@ static int stmt_evaluate_verdict(struct
> > > >eval_ctx *ctx, struct stmt *stmt)
> > > >>  	case EXPR_VERDICT:
> > > >>  		if (stmt->expr->verdict != NFT_CONTINUE)
> > > >>  			stmt->flags |= STMT_F_TERMINAL;
> > > >> -		if (stmt->expr->chain != NULL) {
> > > >> -			if (expr_evaluate(ctx, &stmt->expr->chain) < 0)
> > > >> -				return -1;
> > > >> -			if ((stmt->expr->chain->etype != EXPR_SYMBOL &&
> > > >> -			    stmt->expr->chain->etype != EXPR_VALUE) ||
> > > >> -			    stmt->expr->chain->symtype != SYMBOL_VALUE) {
> > > >> -				return stmt_error(ctx, stmt,
> > > >> -						  "invalid verdict chain expression %s\n",
> > > >> -						  expr_name(stmt->expr->chain));
> > > >> -			}
> > > >> -		}
> > > >
> > > >According to my logs, this bit was added by Fernando to cover for
> > > >invalid variable values[1]. So I fear we can't just drop this check.
> > > >
> > > >Cheers, Phil
> > > >
> > > >[1] I didn't check with current sources, but back then the following
> > > >    variable contents were problematic:
> > > >
> > > >    * define foo = @set1 (a set named 'set1' must exist)
> > > >    * define foo = { 1024 }
> > > >    * define foo = *
> > > 
> > > Yes I am looking to the report and why current version fails when the jump is to a non-base chain because I tested that some months ago.
> > > 
> > > I will catch up with more details in a few hours. Sorry for the inconveniences.
> > 
> > Fernando, in case Pablos patch v2 fixes the reported bug, could you
> > followup with a test case?  It would help when someone tries to remove
> > "unneeded code" in the future ;-)
> 
> I'm not sure it's worth a test for this unlikely corner case.
> 
> There are thousands of paths where we're not performing strict
> expression validation as in this case... and if you really want to get
> this right.

Having said this, if you want a test for this specific case, I really
don't mind :-)