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netfilter: nf_conncount: fix zone comparison in tuple dedup

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The "already exists" dedup logic in __nf_conncount_add() decides
whether a connection has already been counted and can be skipped instead
of incrementing the connlimit count.  It compares the conntrack zone of a
list entry with the zone of the connection being added using
nf_ct_zone_id() and nf_ct_zone_equal(), passing conn->zone.dir or
zone->dir as the direction argument.

Those helpers take enum ip_conntrack_dir values: IP_CT_DIR_ORIGINAL is 0
and IP_CT_DIR_REPLY is 1.  However, zone->dir is a u8 bitmask:
NF_CT_ZONE_DIR_ORIG is 1, NF_CT_ZONE_DIR_REPL is 2 and
NF_CT_DEFAULT_ZONE_DIR is 3.  Passing that bitmask as the enum direction
shifts the meaning of every non-zero value.  An ORIG-only zone passes 1
and is tested as REPLY, while REPL-only and default zones pass 2 or 3 and
test bits beyond the valid direction range.  In those cases
nf_ct_zone_id() can fall back to NF_CT_DEFAULT_ZONE_ID instead of using
the real zone id, so different zones can be treated as equal and dedup
collapses to tuple equality alone.

nf_conncount stores and compares the original-direction tuple for a
connection.  If an skb already has an attached conntrack entry,
get_ct_or_tuple_from_skb() explicitly copies
ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, regardless of the packet's
ctinfo.  Therefore the zone comparison in the tuple dedup path must use
IP_CT_DIR_ORIGINAL as well; the zone direction bitmask describes where a
zone id applies, not which direction this conncount tuple represents.

Fix the two dedup comparisons by passing IP_CT_DIR_ORIGINAL directly.
Do not special-case NF_CT_DEFAULT_ZONE_DIR and do not compare raw zone
ids: using the existing helpers with IP_CT_DIR_ORIGINAL preserves the
direction-aware NF_CT_DEFAULT_ZONE_ID fallback.  A default bidirectional
zone contains the ORIG bit, so it naturally returns the real zone id;
reply-only zones continue to fall back for original-direction tuple
comparisons.

Fixes: 21ba8847f8 ("netfilter: nf_conncount: Fix garbage collection with zones")
Fixes: b36e4523d4 ("netfilter: nf_conncount: fix garbage collection confirm race")
Cc: stable@vger.kernel.org
Reported-by: Yizhou Zhao <zhaoyz24@mails.tsinghua.edu.cn>
Reported-by: Yuxiang Yang <yangyx22@mails.tsinghua.edu.cn>
Reported-by: Ao Wang <wangao@seu.edu.cn>
Reported-by: Xuewei Feng <fengxw06@126.com>
Reported-by: Qi Li <qli01@tsinghua.edu.cn>
Reported-by: Ke Xu <xuke@tsinghua.edu.cn>
Assisted-by: Claude-Code:GLM-5.2
Signed-off-by: Yizhou Zhao <zhaoyz24@mails.tsinghua.edu.cn>
Signed-off-by: Florian Westphal <fw@strlen.de>
This commit is contained in:
Yizhou Zhao
2026-07-08 13:27:28 +08:00
committed by Florian Westphal
parent 86f3ce81dd
commit f62c41b491
1 changed files with 3 additions and 3 deletions
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6
net/netfilter/nf_conncount.c
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@@ -211,8 +211,8 @@ static int __nf_conncount_add(struct net *net,
/* Not found, but might be about to be confirmed */
if (PTR_ERR(found) == -EAGAIN) {
if (nf_ct_tuple_equal(&conn->tuple, &tuple) &&
nf_ct_zone_id(&conn->zone, conn->zone.dir) ==
nf_ct_zone_id(zone, zone->dir))
nf_ct_zone_id(&conn->zone, IP_CT_DIR_ORIGINAL) ==
nf_ct_zone_id(zone, IP_CT_DIR_ORIGINAL))
goto out_put; /* already exists */
} else {
collect++;
@@ -223,7 +223,7 @@ static int __nf_conncount_add(struct net *net,
found_ct = nf_ct_tuplehash_to_ctrack(found);
if (nf_ct_tuple_equal(&conn->tuple, &tuple) &&
nf_ct_zone_equal(found_ct, zone, zone->dir)) {
nf_ct_zone_equal(found_ct, zone, IP_CT_DIR_ORIGINAL)) {
/*
* We should not see tuples twice unless someone hooks
* this into a table without "-p tcp --syn".