Re: [PATCH net-next] netfilter: nft_fib: allow from forward/input without iif selector

[Eric Garver <eric@garver.life>]

On Mon, May 20, 2024 at 11:36:35AM +0200, Pablo Neira Ayuso wrote:
> BTW, one more comment below.
> 
> On Fri, May 17, 2024 at 11:38:06AM -0400, Eric Garver wrote:
> > This removes the restriction of needing iif selector in the
> > forward/input hooks for fib lookups when requested result is
> > oif/oifname.
> > 
> > Removing this restriction allows "loose" lookups from the forward hooks.
> > 
> > Signed-off-by: Eric Garver <eric@garver.life>
> > ---
> >  net/ipv4/netfilter/nft_fib_ipv4.c | 3 +--
> >  net/ipv6/netfilter/nft_fib_ipv6.c | 3 +--
> >  net/netfilter/nft_fib.c           | 8 +++-----
> >  3 files changed, 5 insertions(+), 9 deletions(-)
> > 
> > diff --git a/net/ipv4/netfilter/nft_fib_ipv4.c b/net/ipv4/netfilter/nft_fib_ipv4.c
> > index 9eee535c64dd..975a4a809058 100644
> > --- a/net/ipv4/netfilter/nft_fib_ipv4.c
> > +++ b/net/ipv4/netfilter/nft_fib_ipv4.c
> > @@ -116,8 +116,7 @@ void nft_fib4_eval(const struct nft_expr *expr, struct nft_regs *regs,
> >  		fl4.daddr = iph->daddr;
> >  		fl4.saddr = get_saddr(iph->saddr);
> >  	} else {
> > -		if (nft_hook(pkt) == NF_INET_FORWARD &&
> > -		    priv->flags & NFTA_FIB_F_IIF)
> > +		if (nft_hook(pkt) == NF_INET_FORWARD)
> >  			fl4.flowi4_iif = nft_out(pkt)->ifindex;
> 
> is it intentional to remove for the priv->flags & NFTA_FIB_F_IIF here?
> 
> Maybe only the last chunk below is required?
> 
> >  		fl4.daddr = iph->saddr;
> > diff --git a/net/ipv6/netfilter/nft_fib_ipv6.c b/net/ipv6/netfilter/nft_fib_ipv6.c
> > index 36dc14b34388..f95e39e235d3 100644
> > --- a/net/ipv6/netfilter/nft_fib_ipv6.c
> > +++ b/net/ipv6/netfilter/nft_fib_ipv6.c
> > @@ -30,8 +30,7 @@ static int nft_fib6_flowi_init(struct flowi6 *fl6, const struct nft_fib *priv,
> >  		fl6->daddr = iph->daddr;
> >  		fl6->saddr = iph->saddr;
> >  	} else {
> > -		if (nft_hook(pkt) == NF_INET_FORWARD &&
> > -		    priv->flags & NFTA_FIB_F_IIF)
> > +		if (nft_hook(pkt) == NF_INET_FORWARD)
> >  			fl6->flowi6_iif = nft_out(pkt)->ifindex;
> >  
> >  		fl6->daddr = iph->saddr;
> > diff --git a/net/netfilter/nft_fib.c b/net/netfilter/nft_fib.c
> > index 37cfe6dd712d..b58f62195ff3 100644
> > --- a/net/netfilter/nft_fib.c
> > +++ b/net/netfilter/nft_fib.c
> > @@ -35,11 +35,9 @@ int nft_fib_validate(const struct nft_ctx *ctx, const struct nft_expr *expr,
> >  	switch (priv->result) {
> >  	case NFT_FIB_RESULT_OIF:
> >  	case NFT_FIB_RESULT_OIFNAME:
> > -		hooks = (1 << NF_INET_PRE_ROUTING);
> > -		if (priv->flags & NFTA_FIB_F_IIF) {
> > -			hooks |= (1 << NF_INET_LOCAL_IN) |
> > -				 (1 << NF_INET_FORWARD);
> > -		}
> > +		hooks = (1 << NF_INET_PRE_ROUTING) |
> > +			(1 << NF_INET_LOCAL_IN) |
> > +			(1 << NF_INET_FORWARD);
> 
> I mean: This chunk alone to remove the hook restriction should be good?

ACK. I'll retest and post a v2.