From b860e658200af8fdeced2896a1a6c2f0f0692b70 Mon Sep 17 00:00:00 2001 From: Phil Sutter Date: Fri, 3 Feb 2023 17:37:40 +0100 Subject: extensions: libebt_ip: Translation has to match on ether type On one hand, nft refuses th expression in bridge family if layer3 protocol has not been assured by a previous match. On the other, ebt_ip kernel module will only match on IPv4 packets, so there might be a functional change in the translation versus the original. Instead of just always emitting an 'ether type' match, decide whether it's actually needed - explicit "ip " payload matches (or icmp ones) cause implicit creation of a match on IPv4 by nft. Fixes: 03ecffe6c2cc0 ("ebtables-compat: add initial translations") Signed-off-by: Phil Sutter --- extensions/libebt_ip.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'extensions/libebt_ip.c') diff --git a/extensions/libebt_ip.c b/extensions/libebt_ip.c index 8b381aa1..68f34bff 100644 --- a/extensions/libebt_ip.c +++ b/extensions/libebt_ip.c @@ -432,6 +432,24 @@ static void brip_xlate_nh(struct xt_xlate *xl, xtables_ipmask_to_numeric(maskp)); } +static bool may_skip_ether_type_dep(uint8_t flags) +{ + /* these convert to "ip (s|d)addr" matches */ + if (flags & (EBT_IP_SOURCE | EBT_IP_DEST)) + return true; + + /* icmp match triggers implicit ether type dependency in nft */ + if (flags & EBT_IP_ICMP) + return true; + + /* allow if "ip protocol" match is created by brip_xlate() */ + if (flags & EBT_IP_PROTO && + !(flags & (EBT_IP_SPORT | EBT_IP_DPORT | EBT_IP_ICMP))) + return true; + + return false; +} + static int brip_xlate(struct xt_xlate *xl, const struct xt_xlate_mt_params *params) { @@ -441,6 +459,9 @@ static int brip_xlate(struct xt_xlate *xl, brip_xlate_nh(xl, info, EBT_IP_SOURCE); brip_xlate_nh(xl, info, EBT_IP_DEST); + if (!may_skip_ether_type_dep(info->bitmask)) + xt_xlate_add(xl, "ether type ip "); + if (info->bitmask & EBT_IP_TOS) { xt_xlate_add(xl, "@nh,8,8 "); if (info->invflags & EBT_IP_TOS) -- cgit v1.2.3