Hi Florian,
On Mon, Jun 10, 2019 at 11:44:33AM +0200, Florian Westphal wrote:
> we...@ucloud.cn <we...@ucloud.cn> wrote:
> > From: wenxu <we...@ucloud.cn>
> >
> > nft add rule bridge firewall rule-100-ingress ip protocol icmp drop
>
> nft --debug=netlink add rule bridge firewall rule-100-ingress ip protocol
> icmp drop
> bridge firewall rule-100-ingress
> [ payload load 2b @ link header + 12 => reg 1 ]
> [ cmp eq reg 1 0x00000008 ]
> [ payload load 1b @ network header + 9 => reg 1 ]
> [ cmp eq reg 1 0x00000001 ]
> [ immediate reg 0 drop ]
>
> so problem is that nft inserts a dependency on the ethernet protocol
> type (0x800).
>
> But when vlan is involved, that will fail to compare.
>
> It would also fail for qinq etc.
>
> Because of vlan tag offload, the rule about will probably already work
> just fine when nft userspace is patched to insert the dependency based
> on 'meta protocol'. Can you see if this patch works?
>
> Subject: Change bridge l3 dependency to meta protocol
>
> This examines skb->protocol instead of ethernet header type, which
> might be different when vlan is involved.
>
> nft payload expression will re-insert the vlan tag so ether type
> will not be ETH_P_IP.
>
> ---
> src/meta.c | 6 +++++-
> src/payload.c | 20 ++++++++++++++++++++
> 2 files changed, 25 insertions(+), 1 deletion(-)
>
> diff --git a/src/meta.c b/src/meta.c
> index 583e790ff47d..1e8964eb48c4 100644
> --- a/src/meta.c
> +++ b/src/meta.c
> @@ -539,7 +539,11 @@ static void meta_expr_pctx_update(struct proto_ctx *ctx,
> proto_ctx_update(ctx, PROTO_BASE_TRANSPORT_HDR,
> &expr->location, desc);
> break;
> case NFT_META_PROTOCOL:
> - if (h->base < PROTO_BASE_NETWORK_HDR && ctx->family !=
> NFPROTO_NETDEV)
> + if (h->base != PROTO_BASE_LL_HDR)
> + return;
> +
> + if (ctx->family != NFPROTO_NETDEV &&
> + ctx->family != NFPROTO_BRIDGE)
> return;
>
> desc = proto_find_upper(h->desc,
> ntohs(mpz_get_uint16(right->value)));
> diff --git a/src/payload.c b/src/payload.c
> index 6a8118ece890..c99bb2f69977 100644
> --- a/src/payload.c
> +++ b/src/payload.c
> @@ -18,6 +18,7 @@
> #include <net/if_arp.h>
> #include <arpa/inet.h>
> #include <linux/netfilter.h>
> +#include <linux/if_ether.h>
>
> #include <rule.h>
> #include <expression.h>
> @@ -307,6 +308,19 @@ payload_gen_special_dependency(struct eval_ctx *ctx,
> const struct expr *expr)
> return NULL;
> }
>
> +static const struct proto_desc proto_metaeth = {
> + .name = "ethmeta",
> + .base = PROTO_BASE_LL_HDR,
> + .protocols = {
> + PROTO_LINK(__constant_htons(ETH_P_IP), &proto_ip),
> + PROTO_LINK(__constant_htons(ETH_P_ARP), &proto_arp),
> + PROTO_LINK(__constant_htons(ETH_P_IPV6), &proto_ip6),
> + },
> + .templates = {
> + [0] = PROTO_META_TEMPLATE("protocol", ðertype_type,
> NFT_META_PROTOCOL, 16),
> + },
> +};
> +
> /**
> * payload_gen_dependency - generate match expression on payload dependency
> *
> @@ -369,6 +383,12 @@ int payload_gen_dependency(struct eval_ctx *ctx, const
> struct expr *expr,
> "no %s protocol specified",
> proto_base_names[expr->payload.base - 1]);
>
> + if (ctx->pctx.family == NFPROTO_BRIDGE && desc == &proto_eth) {
> + if (expr->payload.desc == &proto_ip ||
> + expr->payload.desc == &proto_ip6)
> + desc = &proto_metaeth;
> + }i
Is this sufficient to restrict the matching? Is this still buggy from
ingress?
I wonder if an explicit NFT_PAYLOAD_CHECK_VLAN flag would be useful in
the kernel, if so we could rename NFTA_PAYLOAD_CSUM_FLAGS to
NFTA_PAYLOAD_FLAGS and place it there. Just an idea.
Thanks!
