netdev - [PATCH net 2/3] netfilter: conntrack: fix reading nf_conntrack

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210112222033.9732-3-pablo@netfilter.org>
Date:   Tue, 12 Jan 2021 23:20:32 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org, kuba@...nel.org
Subject: [PATCH net 2/3] netfilter: conntrack: fix reading nf_conntrack_buckets

From: Jesper Dangaard Brouer <brouer@...hat.com>

The old way of changing the conntrack hashsize runtime was through changing
the module param via file /sys/module/nf_conntrack/parameters/hashsize. This
was extended to sysctl change in commit 3183ab8997a4 ("netfilter: conntrack:
allow increasing bucket size via sysctl too").

The commit introduced second "user" variable nf_conntrack_htable_size_user
which shadow actual variable nf_conntrack_htable_size. When hashsize is
changed via module param this "user" variable isn't updated. This results in
sysctl net/netfilter/nf_conntrack_buckets shows the wrong value when users
update via the old way.

This patch fix the issue by always updating "user" variable when reading the
proc file. This will take care of changes to the actual variable without
sysctl need to be aware.

Fixes: 3183ab8997a4 ("netfilter: conntrack: allow increasing bucket size via sysctl too")
Reported-by: Yoel Caspersen <yoel@...knet.dk>
Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
Acked-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/nf_conntrack_standalone.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
index 46c5557c1fec..0ee702d374b0 100644
--- a/net/netfilter/nf_conntrack_standalone.c
+++ b/net/netfilter/nf_conntrack_standalone.c
@@ -523,6 +523,9 @@ nf_conntrack_hash_sysctl(struct ctl_table *table, int write,
 {
 	int ret;

+	/* module_param hashsize could have changed value */
+	nf_conntrack_htable_size_user = nf_conntrack_htable_size;
+
 	ret = proc_dointvec(table, write, buffer, lenp, ppos);
 	if (ret < 0 || !write)
 		return ret;
-- 
2.20.1