From 60a3815da702fd9e4759945f26cce5c47d3967ad Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Thu, 8 Oct 2020 01:14:47 +0200 Subject: [PATCH] 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 --- 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 ca9e63d..6a6179a 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 c82f779..63d0321 100644 --- a/net/netfilter/core.c +++ b/net/netfilter/core.c @@ -282,6 +282,16 @@ nf_hook_entry_head(struct net *net, int pf, unsigned int 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)) return NULL; @@ -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); -- 2.7.4