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

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

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?

Thanks.

>  		break;
>  	case NFT_FIB_RESULT_ADDRTYPE:
>  		if (priv->flags & NFTA_FIB_F_IIF)
> -- 
> 2.43.0
>