Re: [PATCH nf 1/2] netfilter: fib: check correct rtable in vrf setups

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

On Wed, Oct 09, 2024 at 09:19:02AM +0200, Florian Westphal wrote:
> We need to init l3mdev unconditionally, else main routing table is searched
> and incorrect result is returned unless strict (iif keyword) matching is
> requested.
> 
> Next patch adds a selftest for this.

Fixes: 2a8a7c0eaa87 ("netfilter: nft_fib: Fix for rpath check with VRF devices")

> Closes: https://bugzilla.netfilter.org/show_bug.cgi?id=1761
> Signed-off-by: Florian Westphal <fw@strlen.de>
> ---
>  net/ipv4/netfilter/nft_fib_ipv4.c | 4 +---
>  net/ipv6/netfilter/nft_fib_ipv6.c | 5 +++--
>  2 files changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/net/ipv4/netfilter/nft_fib_ipv4.c b/net/ipv4/netfilter/nft_fib_ipv4.c
> index 00da1332bbf1..09fff5d424ef 100644
> --- a/net/ipv4/netfilter/nft_fib_ipv4.c
> +++ b/net/ipv4/netfilter/nft_fib_ipv4.c
> @@ -65,6 +65,7 @@ void nft_fib4_eval(const struct nft_expr *expr, struct nft_regs *regs,
>  		.flowi4_scope = RT_SCOPE_UNIVERSE,
>  		.flowi4_iif = LOOPBACK_IFINDEX,
>  		.flowi4_uid = sock_net_uid(nft_net(pkt), NULL),
> +		.flowi4_l3mdev = l3mdev_master_ifindex_rcu(nft_in(pkt)),
>  	};
>  	const struct net_device *oif;
>  	const struct net_device *found;
> @@ -83,9 +84,6 @@ void nft_fib4_eval(const struct nft_expr *expr, struct nft_regs *regs,
>  	else
>  		oif = NULL;
>  
> -	if (priv->flags & NFTA_FIB_F_IIF)
> -		fl4.flowi4_l3mdev = l3mdev_master_ifindex_rcu(oif);
> -
>  	if (nft_hook(pkt) == NF_INET_PRE_ROUTING &&
>  	    nft_fib_is_loopback(pkt->skb, nft_in(pkt))) {
>  		nft_fib_store_result(dest, priv, nft_in(pkt));
> diff --git a/net/ipv6/netfilter/nft_fib_ipv6.c b/net/ipv6/netfilter/nft_fib_ipv6.c
> index 36dc14b34388..c9f1634b3838 100644
> --- a/net/ipv6/netfilter/nft_fib_ipv6.c
> +++ b/net/ipv6/netfilter/nft_fib_ipv6.c
> @@ -41,8 +41,6 @@ static int nft_fib6_flowi_init(struct flowi6 *fl6, const struct nft_fib *priv,
>  	if (ipv6_addr_type(&fl6->daddr) & IPV6_ADDR_LINKLOCAL) {
>  		lookup_flags |= RT6_LOOKUP_F_IFACE;
>  		fl6->flowi6_oif = get_ifindex(dev ? dev : pkt->skb->dev);
> -	} else if (priv->flags & NFTA_FIB_F_IIF) {
> -		fl6->flowi6_l3mdev = l3mdev_master_ifindex_rcu(dev);
>  	}
>  
>  	if (ipv6_addr_type(&fl6->saddr) & IPV6_ADDR_UNICAST)
> @@ -75,6 +73,8 @@ static u32 __nft_fib6_eval_type(const struct nft_fib *priv,
>  	else if (priv->flags & NFTA_FIB_F_OIF)
>  		dev = nft_out(pkt);
>  
> +	fl6.flowi6_l3mdev = l3mdev_master_ifindex_rcu(dev);
> +
>  	nft_fib6_flowi_init(&fl6, priv, pkt, dev, iph);
>  
>  	if (dev && nf_ipv6_chk_addr(nft_net(pkt), &fl6.daddr, dev, true))
> @@ -165,6 +165,7 @@ void nft_fib6_eval(const struct nft_expr *expr, struct nft_regs *regs,
>  		.flowi6_iif = LOOPBACK_IFINDEX,
>  		.flowi6_proto = pkt->tprot,
>  		.flowi6_uid = sock_net_uid(nft_net(pkt), NULL),
> +		.flowi6_l3mdev = l3mdev_master_ifindex_rcu(nft_in(pkt)),
>  	};
>  	struct rt6_info *rt;
>  	int lookup_flags;
> -- 
> 2.46.2
> 
>