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Message-Id: <20201012013819.23128-5-pablo@netfilter.org>
Date: Mon, 12 Oct 2020 03:38:17 +0200
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 4/6] netfilter: add inet ingress support
This patch adds the NF_INET_INGRESS pseudohook for the NFPROTO_INET
family. This is a mapping this new hook to the existing NFPROTO_NETDEV
and NF_NETDEV_INGRESS hook. The hook does not guarantee that packets are
inet only, users must filter out non-ip traffic explicitly.
This infrastructure makes it easier to support this new hook in nf_tables.
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
include/uapi/linux/netfilter.h | 1 +
net/netfilter/core.c | 103 ++++++++++++++++++++++++++-------
2 files changed, 83 insertions(+), 21 deletions(-)
diff --git a/include/uapi/linux/netfilter.h b/include/uapi/linux/netfilter.h
index ca9e63d6e0e4..6a6179af0d7c 100644
--- a/include/uapi/linux/netfilter.h
+++ b/include/uapi/linux/netfilter.h
@@ -45,6 +45,7 @@ enum nf_inet_hooks {
NF_INET_FORWARD,
NF_INET_LOCAL_OUT,
NF_INET_POST_ROUTING,
+ NF_INET_INGRESS,
NF_INET_NUMHOOKS
};
diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index c82f779a587e..63d032191e62 100644
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -281,6 +281,16 @@ nf_hook_entry_head(struct net *net, int pf, unsigned int hooknum,
if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_bridge) <= hooknum))
return NULL;
return net->nf.hooks_bridge + hooknum;
+#endif
+#ifdef CONFIG_NETFILTER_INGRESS
+ case NFPROTO_INET:
+ if (WARN_ON_ONCE(hooknum != NF_INET_INGRESS))
+ return NULL;
+ if (!dev || dev_net(dev) != net) {
+ WARN_ON_ONCE(1);
+ return NULL;
+ }
+ return &dev->nf_hooks_ingress;
#endif
case NFPROTO_IPV4:
if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_ipv4) <= hooknum))
@@ -311,22 +321,56 @@ nf_hook_entry_head(struct net *net, int pf, unsigned int hooknum,
return NULL;
}
+static int nf_ingress_check(struct net *net, const struct nf_hook_ops *reg,
+ int hooknum)
+{
+#ifndef CONFIG_NETFILTER_INGRESS
+ if (reg->hooknum == hooknum)
+ return -EOPNOTSUPP;
+#endif
+ if (reg->hooknum != hooknum ||
+ !reg->dev || dev_net(reg->dev) != net)
+ return -EINVAL;
+
+ return 0;
+}
+
static inline bool nf_ingress_hook(const struct nf_hook_ops *reg, int pf)
{
- return pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS;
+ if ((pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS) ||
+ (pf == NFPROTO_INET && reg->hooknum == NF_INET_INGRESS))
+ return true;
+
+ return false;
}
static void nf_static_key_inc(const struct nf_hook_ops *reg, int pf)
{
#ifdef CONFIG_JUMP_LABEL
- static_key_slow_inc(&nf_hooks_needed[pf][reg->hooknum]);
+ int hooknum;
+
+ if (pf == NFPROTO_INET && reg->hooknum == NF_INET_INGRESS) {
+ pf = NFPROTO_NETDEV;
+ hooknum = NF_NETDEV_INGRESS;
+ } else {
+ hooknum = reg->hooknum;
+ }
+ static_key_slow_inc(&nf_hooks_needed[pf][hooknum]);
#endif
}
static void nf_static_key_dec(const struct nf_hook_ops *reg, int pf)
{
#ifdef CONFIG_JUMP_LABEL
- static_key_slow_dec(&nf_hooks_needed[pf][reg->hooknum]);
+ int hooknum;
+
+ if (pf == NFPROTO_INET && reg->hooknum == NF_INET_INGRESS) {
+ pf = NFPROTO_NETDEV;
+ hooknum = NF_NETDEV_INGRESS;
+ } else {
+ hooknum = reg->hooknum;
+ }
+ static_key_slow_dec(&nf_hooks_needed[pf][hooknum]);
#endif
}
@@ -335,15 +379,22 @@ static int __nf_register_net_hook(struct net *net, int pf,
{
struct nf_hook_entries *p, *new_hooks;
struct nf_hook_entries __rcu **pp;
+ int err;
- if (pf == NFPROTO_NETDEV) {
-#ifndef CONFIG_NETFILTER_INGRESS
- if (reg->hooknum == NF_NETDEV_INGRESS)
- return -EOPNOTSUPP;
-#endif
- if (reg->hooknum != NF_NETDEV_INGRESS ||
- !reg->dev || dev_net(reg->dev) != net)
- return -EINVAL;
+ switch (pf) {
+ case NFPROTO_NETDEV:
+ err = nf_ingress_check(net, reg, NF_NETDEV_INGRESS);
+ if (err < 0)
+ return err;
+ break;
+ case NFPROTO_INET:
+ if (reg->hooknum != NF_INET_INGRESS)
+ break;
+
+ err = nf_ingress_check(net, reg, NF_INET_INGRESS);
+ if (err < 0)
+ return err;
+ break;
}
pp = nf_hook_entry_head(net, pf, reg->hooknum, reg->dev);
@@ -441,8 +492,12 @@ static void __nf_unregister_net_hook(struct net *net, int pf,
void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
{
if (reg->pf == NFPROTO_INET) {
- __nf_unregister_net_hook(net, NFPROTO_IPV4, reg);
- __nf_unregister_net_hook(net, NFPROTO_IPV6, reg);
+ if (reg->hooknum == NF_INET_INGRESS) {
+ __nf_unregister_net_hook(net, NFPROTO_INET, reg);
+ } else {
+ __nf_unregister_net_hook(net, NFPROTO_IPV4, reg);
+ __nf_unregister_net_hook(net, NFPROTO_IPV6, reg);
+ }
} else {
__nf_unregister_net_hook(net, reg->pf, reg);
}
@@ -467,14 +522,20 @@ int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
int err;
if (reg->pf == NFPROTO_INET) {
- err = __nf_register_net_hook(net, NFPROTO_IPV4, reg);
- if (err < 0)
- return err;
-
- err = __nf_register_net_hook(net, NFPROTO_IPV6, reg);
- if (err < 0) {
- __nf_unregister_net_hook(net, NFPROTO_IPV4, reg);
- return err;
+ if (reg->hooknum == NF_INET_INGRESS) {
+ err = __nf_register_net_hook(net, NFPROTO_INET, reg);
+ if (err < 0)
+ return err;
+ } else {
+ err = __nf_register_net_hook(net, NFPROTO_IPV4, reg);
+ if (err < 0)
+ return err;
+
+ err = __nf_register_net_hook(net, NFPROTO_IPV6, reg);
+ if (err < 0) {
+ __nf_unregister_net_hook(net, NFPROTO_IPV4, reg);
+ return err;
+ }
}
} else {
err = __nf_register_net_hook(net, reg->pf, reg);
--
2.20.1
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