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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 
Revert "netfilter: nat: force port remap to prevent shadowing well-known ports"
 
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
Raw File
gup_test.h 
/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef __GUP_TEST_H
#define __GUP_TEST_H

#include <linux/types.h>

#define GUP_FAST_BENCHMARK	_IOWR('g', 1, struct gup_test)
#define PIN_FAST_BENCHMARK	_IOWR('g', 2, struct gup_test)
#define PIN_LONGTERM_BENCHMARK	_IOWR('g', 3, struct gup_test)
#define GUP_BASIC_TEST		_IOWR('g', 4, struct gup_test)
#define PIN_BASIC_TEST		_IOWR('g', 5, struct gup_test)
#define DUMP_USER_PAGES_TEST	_IOWR('g', 6, struct gup_test)

#define GUP_TEST_MAX_PAGES_TO_DUMP		8

#define GUP_TEST_FLAG_DUMP_PAGES_USE_PIN	0x1

struct gup_test {
	__u64 get_delta_usec;
	__u64 put_delta_usec;
	__u64 addr;
	__u64 size;
	__u32 nr_pages_per_call;
	__u32 gup_flags;
	__u32 test_flags;
	/*
	 * Each non-zero entry is the number of the page (1-based: first page is
	 * page 1, so that zero entries mean "do nothing") from the .addr base.
	 */
	__u32 which_pages[GUP_TEST_MAX_PAGES_TO_DUMP];
};

#endif	/* __GUP_TEST_H */
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