[PATCH 5.14 052/151] netfilter: conntrack: fix boot failure with nf_conntrack.enable_hooks=1

Greg Kroah-Hartman
2021-10-11T14:03:49Z

From: Florian Westphal <fw@strlen.de>

[ Upstream commit 339031bafe6b281cf2dcb8364217288b9fdab555 ]

This is a revert of
7b1957b049 ("netfilter: nf_defrag_ipv4: use net_generic infra")
and a partial revert of
8b0adbe3e3 ("netfilter: nf_defrag_ipv6: use net_generic infra").

If conntrack is builtin and kernel is booted with:
nf_conntrack.enable_hooks=1

.... kernel will fail to boot due to a NULL deref in
nf_defrag_ipv4_enable(): Its called before the ipv4 defrag initcall is
made, so net_generic() returns NULL.

To resolve this, move the user refcount back to struct net so calls
to those functions are possible even before their initcalls have run.

Fixes: 7b1957b04956 ("netfilter: nf_defrag_ipv4: use net_generic infra")
Fixes: 8b0adbe3e38d ("netfilter: nf_defrag_ipv6: use net_generic infra").
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/net/netfilter/ipv6/nf_defrag_ipv6.h | 1 -
include/net/netns/netfilter.h | 6 +++++
net/ipv4/netfilter/nf_defrag_ipv4.c | 30 +++++++--------------
net/ipv6/netfilter/nf_conntrack_reasm.c | 2 +-
net/ipv6/netfilter/nf_defrag_ipv6_hooks.c | 25 +++++++----------
5 files changed, 25 insertions(+), 39 deletions(-)

diff --git a/include/net/netfilter/ipv6/nf_defrag_ipv6.h b/include/net/netfilter/ipv6/nf_defrag_ipv6.h
index 0fd8a4159662..ceadf8ba25a4 100644
--- a/include/net/netfilter/ipv6/nf_defrag_ipv6.h
+++ b/include/net/netfilter/ipv6/nf_defrag_ipv6.h
@@ -17,7 +17,6 @@ struct inet_frags_ctl;
struct nft_ct_frag6_pernet {
struct ctl_table_header *nf_frag_frags_hdr;
struct fqdir *fqdir;
- unsigned int users;
};

#endif /* _NF_DEFRAG_IPV6_H */
diff --git a/include/net/netns/netfilter.h b/include/net/netns/netfilter.h
index 15e2b13fb0c0..71343b969cd3 100644
--- a/include/net/netns/netfilter.h
+++ b/include/net/netns/netfilter.h
@@ -28,5 +28,11 @@ struct netns_nf {
#if IS_ENABLED(CONFIG_DECNET)
struct nf_hook_entries __rcu *hooks_decnet[NF_DN_NUMHOOKS];
#endif
+#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4)
+ unsigned int defrag_ipv4_users;
+#endif
+#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
+ unsigned int defrag_ipv6_users;
+#endif
};
#endif
diff --git a/net/ipv4/netfilter/nf_defrag_ipv4.c b/net/ipv4/netfilter/nf_defrag_ipv4.c
index 613432a36f0a..e61ea428ea18 100644
--- a/net/ipv4/netfilter/nf_defrag_ipv4.c
+++ b/net/ipv4/netfilter/nf_defrag_ipv4.c
@@ -20,13 +20,8 @@
#endif
#include <net/netfilter/nf_conntrack_zones.h>

-static unsigned int defrag4_pernet_id __read_mostly;
static DEFINE_MUTEX(defrag4_mutex);

-struct defrag4_pernet {
- unsigned int users;
-};
-
static int nf_ct_ipv4_gather_frags(struct net *net, struct sk_buff *skb,
u_int32_t user)
{
@@ -111,19 +106,15 @@ static const struct nf_hook_ops ipv4_defrag_ops[] = {

static void __net_exit defrag4_net_exit(struct net *net)
{
- struct defrag4_pernet *nf_defrag = net_generic(net, defrag4_pernet_id);
-
- if (nf_defrag->users) {
+ if (net->nf.defrag_ipv4_users) {
nf_unregister_net_hooks(net, ipv4_defrag_ops,
ARRAY_SIZE(ipv4_defrag_ops));
- nf_defrag->users = 0;
+ net->nf.defrag_ipv4_users = 0;
}
}

static struct pernet_operations defrag4_net_ops = {
.exit = defrag4_net_exit,
- .id = &defrag4_pernet_id,
- .size = sizeof(struct defrag4_pernet),
};

static int __init nf_defrag_init(void)
@@ -138,24 +129,23 @@ static void __exit nf_defrag_fini(void)

int nf_defrag_ipv4_enable(struct net *net)
{
- struct defrag4_pernet *nf_defrag = net_generic(net, defrag4_pernet_id);
int err = 0;

mutex_lock(&defrag4_mutex);
- if (nf_defrag->users == UINT_MAX) {
+ if (net->nf.defrag_ipv4_users == UINT_MAX) {
err = -EOVERFLOW;
goto out_unlock;
}

- if (nf_defrag->users) {
- nf_defrag->users++;
+ if (net->nf.defrag_ipv4_users) {
+ net->nf.defrag_ipv4_users++;
goto out_unlock;
}

err = nf_register_net_hooks(net, ipv4_defrag_ops,
ARRAY_SIZE(ipv4_defrag_ops));
if (err == 0)
- nf_defrag->users = 1;
+ net->nf.defrag_ipv4_users = 1;

out_unlock:
mutex_unlock(&defrag4_mutex);
@@ -165,12 +155,10 @@ EXPORT_SYMBOL_GPL(nf_defrag_ipv4_enable);

void nf_defrag_ipv4_disable(struct net *net)
{
- struct defrag4_pernet *nf_defrag = net_generic(net, defrag4_pernet_id);
-
mutex_lock(&defrag4_mutex);
- if (nf_defrag->users) {
- nf_defrag->users--;
- if (nf_defrag->users == 0)
+ if (net->nf.defrag_ipv4_users) {
+ net->nf.defrag_ipv4_users--;
+ if (net->nf.defrag_ipv4_users == 0)
nf_unregister_net_hooks(net, ipv4_defrag_ops,
ARRAY_SIZE(ipv4_defrag_ops));
}
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index a0108415275f..5c47be29b9ee 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -33,7 +33,7 @@

static const char nf_frags_cache_name[] = "nf-frags";

-unsigned int nf_frag_pernet_id __read_mostly;
+static unsigned int nf_frag_pernet_id __read_mostly;
static struct inet_frags nf_frags;

static struct nft_ct_frag6_pernet *nf_frag_pernet(struct net *net)
diff --git a/net/ipv6/netfilter/nf_defrag_ipv6_hooks.c b/net/ipv6/netfilter/nf_defrag_ipv6_hooks.c
index e8a59d8bf2ad..cb4eb1d2c620 100644
--- a/net/ipv6/netfilter/nf_defrag_ipv6_hooks.c
+++ b/net/ipv6/netfilter/nf_defrag_ipv6_hooks.c
@@ -25,8 +25,6 @@
#include <net/netfilter/nf_conntrack_zones.h>
#include <net/netfilter/ipv6/nf_defrag_ipv6.h>

-extern unsigned int nf_frag_pernet_id;
-
static DEFINE_MUTEX(defrag6_mutex);

static enum ip6_defrag_users nf_ct6_defrag_user(unsigned int hooknum,
@@ -91,12 +89,10 @@ static const struct nf_hook_ops ipv6_defrag_ops[] = {

static void __net_exit defrag6_net_exit(struct net *net)
{
- struct nft_ct_frag6_pernet *nf_frag = net_generic(net, nf_frag_pernet_id);
-
- if (nf_frag->users) {
+ if (net->nf.defrag_ipv6_users) {
nf_unregister_net_hooks(net, ipv6_defrag_ops,
ARRAY_SIZE(ipv6_defrag_ops));
- nf_frag->users = 0;
+ net->nf.defrag_ipv6_users = 0;
}
}

@@ -134,24 +130,23 @@ static void __exit nf_defrag_fini(void)

int nf_defrag_ipv6_enable(struct net *net)
{
- struct nft_ct_frag6_pernet *nf_frag = net_generic(net, nf_frag_pernet_id);
int err = 0;

mutex_lock(&defrag6_mutex);
- if (nf_frag->users == UINT_MAX) {
+ if (net->nf.defrag_ipv6_users == UINT_MAX) {
err = -EOVERFLOW;
goto out_unlock;
}

- if (nf_frag->users) {
- nf_frag->users++;
+ if (net->nf.defrag_ipv6_users) {
+ net->nf.defrag_ipv6_users++;
goto out_unlock;
}

err = nf_register_net_hooks(net, ipv6_defrag_ops,
ARRAY_SIZE(ipv6_defrag_ops));
if (err == 0)
- nf_frag->users = 1;
+ net->nf.defrag_ipv6_users = 1;

out_unlock:
mutex_unlock(&defrag6_mutex);
@@ -161,12 +156,10 @@ EXPORT_SYMBOL_GPL(nf_defrag_ipv6_enable);

void nf_defrag_ipv6_disable(struct net *net)
{
- struct nft_ct_frag6_pernet *nf_frag = net_generic(net, nf_frag_pernet_id);
-
mutex_lock(&defrag6_mutex);
- if (nf_frag->users) {
- nf_frag->users--;
- if (nf_frag->users == 0)
+ if (net->nf.defrag_ipv6_users) {
+ net->nf.defrag_ipv6_users--;
+ if (net->nf.defrag_ipv6_users == 0)
nf_unregister_net_hooks(net, ipv6_defrag_ops,
ARRAY_SIZE(ipv6_defrag_ops));
}
--
2.33.0