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_dscp.c
// SPDX-License-Identifier: GPL-2.0-only
/* IP tables module for matching the value of the IPv4/IPv6 DSCP field
*
* (C) 2002 by Harald Welte <laforge@netfilter.org>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <net/dsfield.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_dscp.h>
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
MODULE_DESCRIPTION("Xtables: DSCP/TOS field match");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ipt_dscp");
MODULE_ALIAS("ip6t_dscp");
MODULE_ALIAS("ipt_tos");
MODULE_ALIAS("ip6t_tos");
static bool
dscp_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_dscp_info *info = par->matchinfo;
u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;
return (dscp == info->dscp) ^ !!info->invert;
}
static bool
dscp_mt6(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_dscp_info *info = par->matchinfo;
u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT;
return (dscp == info->dscp) ^ !!info->invert;
}
static int dscp_mt_check(const struct xt_mtchk_param *par)
{
const struct xt_dscp_info *info = par->matchinfo;
if (info->dscp > XT_DSCP_MAX)
return -EDOM;
return 0;
}
static bool tos_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_tos_match_info *info = par->matchinfo;
if (xt_family(par) == NFPROTO_IPV4)
return ((ip_hdr(skb)->tos & info->tos_mask) ==
info->tos_value) ^ !!info->invert;
else
return ((ipv6_get_dsfield(ipv6_hdr(skb)) & info->tos_mask) ==
info->tos_value) ^ !!info->invert;
}
static struct xt_match dscp_mt_reg[] __read_mostly = {
{
.name = "dscp",
.family = NFPROTO_IPV4,
.checkentry = dscp_mt_check,
.match = dscp_mt,
.matchsize = sizeof(struct xt_dscp_info),
.me = THIS_MODULE,
},
{
.name = "dscp",
.family = NFPROTO_IPV6,
.checkentry = dscp_mt_check,
.match = dscp_mt6,
.matchsize = sizeof(struct xt_dscp_info),
.me = THIS_MODULE,
},
{
.name = "tos",
.revision = 1,
.family = NFPROTO_IPV4,
.match = tos_mt,
.matchsize = sizeof(struct xt_tos_match_info),
.me = THIS_MODULE,
},
{
.name = "tos",
.revision = 1,
.family = NFPROTO_IPV6,
.match = tos_mt,
.matchsize = sizeof(struct xt_tos_match_info),
.me = THIS_MODULE,
},
};
static int __init dscp_mt_init(void)
{
return xt_register_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
}
static void __exit dscp_mt_exit(void)
{
xt_unregister_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
}
module_init(dscp_mt_init);
module_exit(dscp_mt_exit);
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