Revision a82c25c366b0963d33ddf699196e6cf57f6d89b1 authored by Florian Westphal on 08 March 2022, 12:52:11 UTC, committed by Florian Westphal on 08 March 2022, 12:52:11 UTC
This reverts commit 878aed8db324bec64f3c3f956e64d5ae7375a5de. This change breaks existing setups where conntrack is used with asymmetric paths. In these cases, the NAT transformation occurs on the syn-ack instead of the syn: 1. SYN x:12345 -> y -> 443 // sent by initiator, receiverd by responder 2. SYNACK y:443 -> x:12345 // First packet seen by conntrack, as sent by responder 3. tuple_force_port_remap() gets called, sees: 'tcp from 443 to port 12345 NAT' -> pick a new source port, inititor receives 4. SYNACK y:$RANDOM -> x:12345 // connection is never established While its possible to avoid the breakage with NOTRACK rules, a kernel update should not break working setups. An alternative to the revert is to augment conntrack to tag mid-stream connections plus more code in the nat core to skip NAT for such connections, however, this leads to more interaction/integration between conntrack and NAT. Therefore, revert, users will need to add explicit nat rules to avoid port shadowing. Link: https://lore.kernel.org/netfilter-devel/20220302105908.GA5852@breakpoint.cc/#R Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2051413 Signed-off-by: Florian Westphal <fw@strlen.de>
1 parent f8e9bd3
xt_mark.c
// SPDX-License-Identifier: GPL-2.0-only
/*
* xt_mark - Netfilter module to match NFMARK value
*
* (C) 1999-2001 Marc Boucher <marc@mbsi.ca>
* Copyright © CC Computer Consultants GmbH, 2007 - 2008
* Jan Engelhardt <jengelh@medozas.de>
*/
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netfilter/xt_mark.h>
#include <linux/netfilter/x_tables.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
MODULE_DESCRIPTION("Xtables: packet mark operations");
MODULE_ALIAS("ipt_mark");
MODULE_ALIAS("ip6t_mark");
MODULE_ALIAS("ipt_MARK");
MODULE_ALIAS("ip6t_MARK");
MODULE_ALIAS("arpt_MARK");
static unsigned int
mark_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
const struct xt_mark_tginfo2 *info = par->targinfo;
skb->mark = (skb->mark & ~info->mask) ^ info->mark;
return XT_CONTINUE;
}
static bool
mark_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_mark_mtinfo1 *info = par->matchinfo;
return ((skb->mark & info->mask) == info->mark) ^ info->invert;
}
static struct xt_target mark_tg_reg __read_mostly = {
.name = "MARK",
.revision = 2,
.family = NFPROTO_UNSPEC,
.target = mark_tg,
.targetsize = sizeof(struct xt_mark_tginfo2),
.me = THIS_MODULE,
};
static struct xt_match mark_mt_reg __read_mostly = {
.name = "mark",
.revision = 1,
.family = NFPROTO_UNSPEC,
.match = mark_mt,
.matchsize = sizeof(struct xt_mark_mtinfo1),
.me = THIS_MODULE,
};
static int __init mark_mt_init(void)
{
int ret;
ret = xt_register_target(&mark_tg_reg);
if (ret < 0)
return ret;
ret = xt_register_match(&mark_mt_reg);
if (ret < 0) {
xt_unregister_target(&mark_tg_reg);
return ret;
}
return 0;
}
static void __exit mark_mt_exit(void)
{
xt_unregister_match(&mark_mt_reg);
xt_unregister_target(&mark_tg_reg);
}
module_init(mark_mt_init);
module_exit(mark_mt_exit);
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