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Message-Id: <20220901071238.3044-2-fw@strlen.de>
Date: Thu, 1 Sep 2022 09:12:35 +0200
From: Florian Westphal <fw@...len.de>
To: <netdev@...r.kernel.org>
Cc: davem@...emloft.net, netfilter-devel@...r.kernel.org,
kuba@...nel.org, pabeni@...hat.com, edumazet@...gle.com,
Pablo Neira Ayuso <pablo@...filter.org>,
Aaron Conole <aconole@...hat.com>
Subject: [PATCH net 1/4] netfilter: remove nf_conntrack_helper sysctl and modparam toggles
From: Pablo Neira Ayuso <pablo@...filter.org>
__nf_ct_try_assign_helper() remains in place but it now requires a
template to configure the helper.
A toggle to disable automatic helper assignment was added by:
a9006892643a ("netfilter: nf_ct_helper: allow to disable automatic helper assignment")
in 2012 to address the issues described in "Secure use of iptables and
connection tracking helpers". Automatic conntrack helper assignment was
disabled by:
3bb398d925ec ("netfilter: nf_ct_helper: disable automatic helper assignment")
back in 2016.
This patch removes the sysctl and modparam toggles, users now have to
rely on explicit conntrack helper configuration via ruleset.
Update tools/testing/selftests/netfilter/nft_conntrack_helper.sh to
check that auto-assignment does not happen anymore.
Acked-by: Aaron Conole <aconole@...hat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
include/net/netfilter/nf_conntrack.h | 2 -
include/net/netns/conntrack.h | 1 -
net/netfilter/nf_conntrack_core.c | 7 +-
net/netfilter/nf_conntrack_helper.c | 80 +++----------------
net/netfilter/nf_conntrack_netlink.c | 5 --
net/netfilter/nf_conntrack_standalone.c | 10 ---
net/netfilter/nft_ct.c | 3 -
.../netfilter/nft_conntrack_helper.sh | 36 ++++++---
8 files changed, 37 insertions(+), 107 deletions(-)
diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index a32be8aa7ed2..6a2019aaa464 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -53,8 +53,6 @@ struct nf_conntrack_net {
/* only used when new connection is allocated: */
atomic_t count;
unsigned int expect_count;
- u8 sysctl_auto_assign_helper;
- bool auto_assign_helper_warned;
/* only used from work queues, configuration plane, and so on: */
unsigned int users4;
diff --git a/include/net/netns/conntrack.h b/include/net/netns/conntrack.h
index c396a3862e80..e1290c159184 100644
--- a/include/net/netns/conntrack.h
+++ b/include/net/netns/conntrack.h
@@ -101,7 +101,6 @@ struct netns_ct {
u8 sysctl_log_invalid; /* Log invalid packets */
u8 sysctl_events;
u8 sysctl_acct;
- u8 sysctl_auto_assign_helper;
u8 sysctl_tstamp;
u8 sysctl_checksum;
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 71c2f4f95d36..1357a2729a4b 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1782,7 +1782,7 @@ init_conntrack(struct net *net, struct nf_conn *tmpl,
}
spin_unlock_bh(&nf_conntrack_expect_lock);
}
- if (!exp)
+ if (!exp && tmpl)
__nf_ct_try_assign_helper(ct, tmpl, GFP_ATOMIC);
/* Other CPU might have obtained a pointer to this object before it was
@@ -2068,10 +2068,6 @@ void nf_conntrack_alter_reply(struct nf_conn *ct,
ct->tuplehash[IP_CT_DIR_REPLY].tuple = *newreply;
if (ct->master || (help && !hlist_empty(&help->expectations)))
return;
-
- rcu_read_lock();
- __nf_ct_try_assign_helper(ct, NULL, GFP_ATOMIC);
- rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply);
@@ -2797,7 +2793,6 @@ int nf_conntrack_init_net(struct net *net)
nf_conntrack_acct_pernet_init(net);
nf_conntrack_tstamp_pernet_init(net);
nf_conntrack_ecache_pernet_init(net);
- nf_conntrack_helper_pernet_init(net);
nf_conntrack_proto_pernet_init(net);
return 0;
diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
index e96b32221444..ff737a76052e 100644
--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -35,11 +35,6 @@ unsigned int nf_ct_helper_hsize __read_mostly;
EXPORT_SYMBOL_GPL(nf_ct_helper_hsize);
static unsigned int nf_ct_helper_count __read_mostly;
-static bool nf_ct_auto_assign_helper __read_mostly = false;
-module_param_named(nf_conntrack_helper, nf_ct_auto_assign_helper, bool, 0644);
-MODULE_PARM_DESC(nf_conntrack_helper,
- "Enable automatic conntrack helper assignment (default 0)");
-
static DEFINE_MUTEX(nf_ct_nat_helpers_mutex);
static struct list_head nf_ct_nat_helpers __read_mostly;
@@ -51,24 +46,6 @@ static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
(__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
}
-static struct nf_conntrack_helper *
-__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
-{
- struct nf_conntrack_helper *helper;
- struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
- unsigned int h;
-
- if (!nf_ct_helper_count)
- return NULL;
-
- h = helper_hash(tuple);
- hlist_for_each_entry_rcu(helper, &nf_ct_helper_hash[h], hnode) {
- if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
- return helper;
- }
- return NULL;
-}
-
struct nf_conntrack_helper *
__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
{
@@ -209,33 +186,11 @@ nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp)
}
EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
-static struct nf_conntrack_helper *
-nf_ct_lookup_helper(struct nf_conn *ct, struct net *net)
-{
- struct nf_conntrack_net *cnet = nf_ct_pernet(net);
-
- if (!cnet->sysctl_auto_assign_helper) {
- if (cnet->auto_assign_helper_warned)
- return NULL;
- if (!__nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple))
- return NULL;
- pr_info("nf_conntrack: default automatic helper assignment "
- "has been turned off for security reasons and CT-based "
- "firewall rule not found. Use the iptables CT target "
- "to attach helpers instead.\n");
- cnet->auto_assign_helper_warned = true;
- return NULL;
- }
-
- return __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
-}
-
int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
gfp_t flags)
{
struct nf_conntrack_helper *helper = NULL;
struct nf_conn_help *help;
- struct net *net = nf_ct_net(ct);
/* We already got a helper explicitly attached. The function
* nf_conntrack_alter_reply - in case NAT is in use - asks for looking
@@ -246,23 +201,21 @@ int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
if (test_bit(IPS_HELPER_BIT, &ct->status))
return 0;
- if (tmpl != NULL) {
- help = nfct_help(tmpl);
- if (help != NULL) {
- helper = rcu_dereference(help->helper);
- set_bit(IPS_HELPER_BIT, &ct->status);
- }
+ if (WARN_ON_ONCE(!tmpl))
+ return 0;
+
+ help = nfct_help(tmpl);
+ if (help != NULL) {
+ helper = rcu_dereference(help->helper);
+ set_bit(IPS_HELPER_BIT, &ct->status);
}
help = nfct_help(ct);
if (helper == NULL) {
- helper = nf_ct_lookup_helper(ct, net);
- if (helper == NULL) {
- if (help)
- RCU_INIT_POINTER(help->helper, NULL);
- return 0;
- }
+ if (help)
+ RCU_INIT_POINTER(help->helper, NULL);
+ return 0;
}
if (help == NULL) {
@@ -545,19 +498,6 @@ void nf_nat_helper_unregister(struct nf_conntrack_nat_helper *nat)
}
EXPORT_SYMBOL_GPL(nf_nat_helper_unregister);
-void nf_ct_set_auto_assign_helper_warned(struct net *net)
-{
- nf_ct_pernet(net)->auto_assign_helper_warned = true;
-}
-EXPORT_SYMBOL_GPL(nf_ct_set_auto_assign_helper_warned);
-
-void nf_conntrack_helper_pernet_init(struct net *net)
-{
- struct nf_conntrack_net *cnet = nf_ct_pernet(net);
-
- cnet->sysctl_auto_assign_helper = nf_ct_auto_assign_helper;
-}
-
int nf_conntrack_helper_init(void)
{
nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 04169b54f2a2..7562b215b932 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -2298,11 +2298,6 @@ ctnetlink_create_conntrack(struct net *net,
ct->status |= IPS_HELPER;
RCU_INIT_POINTER(help->helper, helper);
}
- } else {
- /* try an implicit helper assignation */
- err = __nf_ct_try_assign_helper(ct, NULL, GFP_ATOMIC);
- if (err < 0)
- goto err2;
}
err = ctnetlink_setup_nat(ct, cda);
diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
index 05895878610c..4ffe84c5a82c 100644
--- a/net/netfilter/nf_conntrack_standalone.c
+++ b/net/netfilter/nf_conntrack_standalone.c
@@ -561,7 +561,6 @@ enum nf_ct_sysctl_index {
NF_SYSCTL_CT_LOG_INVALID,
NF_SYSCTL_CT_EXPECT_MAX,
NF_SYSCTL_CT_ACCT,
- NF_SYSCTL_CT_HELPER,
#ifdef CONFIG_NF_CONNTRACK_EVENTS
NF_SYSCTL_CT_EVENTS,
#endif
@@ -680,14 +679,6 @@ static struct ctl_table nf_ct_sysctl_table[] = {
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
},
- [NF_SYSCTL_CT_HELPER] = {
- .procname = "nf_conntrack_helper",
- .maxlen = sizeof(u8),
- .mode = 0644,
- .proc_handler = proc_dou8vec_minmax,
- .extra1 = SYSCTL_ZERO,
- .extra2 = SYSCTL_ONE,
- },
#ifdef CONFIG_NF_CONNTRACK_EVENTS
[NF_SYSCTL_CT_EVENTS] = {
.procname = "nf_conntrack_events",
@@ -1100,7 +1091,6 @@ static int nf_conntrack_standalone_init_sysctl(struct net *net)
table[NF_SYSCTL_CT_CHECKSUM].data = &net->ct.sysctl_checksum;
table[NF_SYSCTL_CT_LOG_INVALID].data = &net->ct.sysctl_log_invalid;
table[NF_SYSCTL_CT_ACCT].data = &net->ct.sysctl_acct;
- table[NF_SYSCTL_CT_HELPER].data = &cnet->sysctl_auto_assign_helper;
#ifdef CONFIG_NF_CONNTRACK_EVENTS
table[NF_SYSCTL_CT_EVENTS].data = &net->ct.sysctl_events;
#endif
diff --git a/net/netfilter/nft_ct.c b/net/netfilter/nft_ct.c
index b04995c3e17f..a3f01f209a53 100644
--- a/net/netfilter/nft_ct.c
+++ b/net/netfilter/nft_ct.c
@@ -1089,9 +1089,6 @@ static int nft_ct_helper_obj_init(const struct nft_ctx *ctx,
if (err < 0)
goto err_put_helper;
- /* Avoid the bogus warning, helper will be assigned after CT init */
- nf_ct_set_auto_assign_helper_warned(ctx->net);
-
return 0;
err_put_helper:
diff --git a/tools/testing/selftests/netfilter/nft_conntrack_helper.sh b/tools/testing/selftests/netfilter/nft_conntrack_helper.sh
index bf6b9626c7dd..faa7778d7bd1 100755
--- a/tools/testing/selftests/netfilter/nft_conntrack_helper.sh
+++ b/tools/testing/selftests/netfilter/nft_conntrack_helper.sh
@@ -102,26 +102,42 @@ check_for_helper()
ip netns exec ${netns} conntrack -L -f $family -p tcp --dport $port 2> /dev/null |grep -q 'helper=ftp'
if [ $? -ne 0 ] ; then
- echo "FAIL: ${netns} did not show attached helper $message" 1>&2
- ret=1
+ if [ $autoassign -eq 0 ] ;then
+ echo "FAIL: ${netns} did not show attached helper $message" 1>&2
+ ret=1
+ else
+ echo "PASS: ${netns} did not show attached helper $message" 1>&2
+ fi
+ else
+ if [ $autoassign -eq 0 ] ;then
+ echo "PASS: ${netns} connection on port $port has ftp helper attached" 1>&2
+ else
+ echo "FAIL: ${netns} connection on port $port has ftp helper attached" 1>&2
+ ret=1
+ fi
fi
- echo "PASS: ${netns} connection on port $port has ftp helper attached" 1>&2
return 0
}
test_helper()
{
local port=$1
- local msg=$2
+ local autoassign=$2
+
+ if [ $autoassign -eq 0 ] ;then
+ msg="set via ruleset"
+ else
+ msg="auto-assign"
+ fi
sleep 3 | ip netns exec ${ns2} nc -w 2 -l -p $port > /dev/null &
sleep 1 | ip netns exec ${ns1} nc -w 2 10.0.1.2 $port > /dev/null &
sleep 1
- check_for_helper "$ns1" "ip $msg" $port
- check_for_helper "$ns2" "ip $msg" $port
+ check_for_helper "$ns1" "ip $msg" $port $autoassign
+ check_for_helper "$ns2" "ip $msg" $port $autoassign
wait
@@ -173,9 +189,9 @@ if [ $? -ne 0 ];then
fi
fi
-test_helper 2121 "set via ruleset"
-ip netns exec ${ns1} sysctl -q 'net.netfilter.nf_conntrack_helper=1'
-ip netns exec ${ns2} sysctl -q 'net.netfilter.nf_conntrack_helper=1'
-test_helper 21 "auto-assign"
+test_helper 2121 0
+ip netns exec ${ns1} sysctl -qe 'net.netfilter.nf_conntrack_helper=1'
+ip netns exec ${ns2} sysctl -qe 'net.netfilter.nf_conntrack_helper=1'
+test_helper 21 1
exit $ret
--
2.35.1
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