From d1aca8ab3104aa7131f5ab144c6f586b54df084b Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Tue, 19 Feb 2019 17:38:19 +0100 Subject: netfilter: nat: merge ipv4 and ipv6 masquerade functionality Before: text data bss dec hex filename 13916 1412 4128 19456 4c00 nf_nat.ko 4510 968 4 5482 156a nf_nat_ipv4.ko 5146 944 8 6098 17d2 nf_nat_ipv6.ko After: text data bss dec hex filename 16566 1576 4136 22278 5706 nf_nat.ko 3187 844 0 4031 fbf nf_nat_ipv4.ko 3598 844 0 4442 115a nf_nat_ipv6.ko ... so no drastic changes in combined size. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_nat_masquerade.c | 362 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 362 insertions(+) create mode 100644 net/netfilter/nf_nat_masquerade.c (limited to 'net/netfilter/nf_nat_masquerade.c') diff --git a/net/netfilter/nf_nat_masquerade.c b/net/netfilter/nf_nat_masquerade.c new file mode 100644 index 000000000000..86fa4dcc63c5 --- /dev/null +++ b/net/netfilter/nf_nat_masquerade.c @@ -0,0 +1,362 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include +#include +#include +#include + +#include +#include + +static DEFINE_MUTEX(masq_mutex); +static unsigned int masq_refcnt __read_mostly; + +unsigned int +nf_nat_masquerade_ipv4(struct sk_buff *skb, unsigned int hooknum, + const struct nf_nat_range2 *range, + const struct net_device *out) +{ + struct nf_conn *ct; + struct nf_conn_nat *nat; + enum ip_conntrack_info ctinfo; + struct nf_nat_range2 newrange; + const struct rtable *rt; + __be32 newsrc, nh; + + WARN_ON(hooknum != NF_INET_POST_ROUTING); + + ct = nf_ct_get(skb, &ctinfo); + + WARN_ON(!(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED || + ctinfo == IP_CT_RELATED_REPLY))); + + /* Source address is 0.0.0.0 - locally generated packet that is + * probably not supposed to be masqueraded. + */ + if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip == 0) + return NF_ACCEPT; + + rt = skb_rtable(skb); + nh = rt_nexthop(rt, ip_hdr(skb)->daddr); + newsrc = inet_select_addr(out, nh, RT_SCOPE_UNIVERSE); + if (!newsrc) { + pr_info("%s ate my IP address\n", out->name); + return NF_DROP; + } + + nat = nf_ct_nat_ext_add(ct); + if (nat) + nat->masq_index = out->ifindex; + + /* Transfer from original range. */ + memset(&newrange.min_addr, 0, sizeof(newrange.min_addr)); + memset(&newrange.max_addr, 0, sizeof(newrange.max_addr)); + newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS; + newrange.min_addr.ip = newsrc; + newrange.max_addr.ip = newsrc; + newrange.min_proto = range->min_proto; + newrange.max_proto = range->max_proto; + + /* Hand modified range to generic setup. */ + return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC); +} +EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv4); + +static int device_cmp(struct nf_conn *i, void *ifindex) +{ + const struct nf_conn_nat *nat = nfct_nat(i); + + if (!nat) + return 0; + return nat->masq_index == (int)(long)ifindex; +} + +static int masq_device_event(struct notifier_block *this, + unsigned long event, + void *ptr) +{ + const struct net_device *dev = netdev_notifier_info_to_dev(ptr); + struct net *net = dev_net(dev); + + if (event == NETDEV_DOWN) { + /* Device was downed. Search entire table for + * conntracks which were associated with that device, + * and forget them. + */ + + nf_ct_iterate_cleanup_net(net, device_cmp, + (void *)(long)dev->ifindex, 0, 0); + } + + return NOTIFY_DONE; +} + +static int inet_cmp(struct nf_conn *ct, void *ptr) +{ + struct in_ifaddr *ifa = (struct in_ifaddr *)ptr; + struct net_device *dev = ifa->ifa_dev->dev; + struct nf_conntrack_tuple *tuple; + + if (!device_cmp(ct, (void *)(long)dev->ifindex)) + return 0; + + tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple; + + return ifa->ifa_address == tuple->dst.u3.ip; +} + +static int masq_inet_event(struct notifier_block *this, + unsigned long event, + void *ptr) +{ + struct in_device *idev = ((struct in_ifaddr *)ptr)->ifa_dev; + struct net *net = dev_net(idev->dev); + + /* The masq_dev_notifier will catch the case of the device going + * down. So if the inetdev is dead and being destroyed we have + * no work to do. Otherwise this is an individual address removal + * and we have to perform the flush. + */ + if (idev->dead) + return NOTIFY_DONE; + + if (event == NETDEV_DOWN) + nf_ct_iterate_cleanup_net(net, inet_cmp, ptr, 0, 0); + + return NOTIFY_DONE; +} + +static struct notifier_block masq_dev_notifier = { + .notifier_call = masq_device_event, +}; + +static struct notifier_block masq_inet_notifier = { + .notifier_call = masq_inet_event, +}; + +int nf_nat_masquerade_ipv4_register_notifier(void) +{ + int ret = 0; + + mutex_lock(&masq_mutex); + /* check if the notifier was already set */ + if (++masq_refcnt > 1) + goto out_unlock; + + /* Register for device down reports */ + ret = register_netdevice_notifier(&masq_dev_notifier); + if (ret) + goto err_dec; + /* Register IP address change reports */ + ret = register_inetaddr_notifier(&masq_inet_notifier); + if (ret) + goto err_unregister; + + mutex_unlock(&masq_mutex); + return ret; + +err_unregister: + unregister_netdevice_notifier(&masq_dev_notifier); +err_dec: + masq_refcnt--; +out_unlock: + mutex_unlock(&masq_mutex); + return ret; +} +EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv4_register_notifier); + +void nf_nat_masquerade_ipv4_unregister_notifier(void) +{ + mutex_lock(&masq_mutex); + /* check if the notifier still has clients */ + if (--masq_refcnt > 0) + goto out_unlock; + + unregister_netdevice_notifier(&masq_dev_notifier); + unregister_inetaddr_notifier(&masq_inet_notifier); +out_unlock: + mutex_unlock(&masq_mutex); +} +EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv4_unregister_notifier); + +#if IS_ENABLED(CONFIG_IPV6) +static atomic_t v6_worker_count __read_mostly; + +static int +nat_ipv6_dev_get_saddr(struct net *net, const struct net_device *dev, + const struct in6_addr *daddr, unsigned int srcprefs, + struct in6_addr *saddr) +{ +#ifdef CONFIG_IPV6_MODULE + const struct nf_ipv6_ops *v6_ops = nf_get_ipv6_ops(); + + if (!v6_ops) + return -EHOSTUNREACH; + + return v6_ops->dev_get_saddr(net, dev, daddr, srcprefs, saddr); +#else + return ipv6_dev_get_saddr(net, dev, daddr, srcprefs, saddr); +#endif +} + +unsigned int +nf_nat_masquerade_ipv6(struct sk_buff *skb, const struct nf_nat_range2 *range, + const struct net_device *out) +{ + enum ip_conntrack_info ctinfo; + struct nf_conn_nat *nat; + struct in6_addr src; + struct nf_conn *ct; + struct nf_nat_range2 newrange; + + ct = nf_ct_get(skb, &ctinfo); + WARN_ON(!(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED || + ctinfo == IP_CT_RELATED_REPLY))); + + if (nat_ipv6_dev_get_saddr(nf_ct_net(ct), out, + &ipv6_hdr(skb)->daddr, 0, &src) < 0) + return NF_DROP; + + nat = nf_ct_nat_ext_add(ct); + if (nat) + nat->masq_index = out->ifindex; + + newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS; + newrange.min_addr.in6 = src; + newrange.max_addr.in6 = src; + newrange.min_proto = range->min_proto; + newrange.max_proto = range->max_proto; + + return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC); +} +EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6); + +struct masq_dev_work { + struct work_struct work; + struct net *net; + struct in6_addr addr; + int ifindex; +}; + +static int inet6_cmp(struct nf_conn *ct, void *work) +{ + struct masq_dev_work *w = (struct masq_dev_work *)work; + struct nf_conntrack_tuple *tuple; + + if (!device_cmp(ct, (void *)(long)w->ifindex)) + return 0; + + tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple; + + return ipv6_addr_equal(&w->addr, &tuple->dst.u3.in6); +} + +static void iterate_cleanup_work(struct work_struct *work) +{ + struct masq_dev_work *w; + + w = container_of(work, struct masq_dev_work, work); + + nf_ct_iterate_cleanup_net(w->net, inet6_cmp, (void *)w, 0, 0); + + put_net(w->net); + kfree(w); + atomic_dec(&v6_worker_count); + module_put(THIS_MODULE); +} + +/* atomic notifier; can't call nf_ct_iterate_cleanup_net (it can sleep). + * + * Defer it to the system workqueue. + * + * As we can have 'a lot' of inet_events (depending on amount of ipv6 + * addresses being deleted), we also need to limit work item queue. + */ +static int masq_inet6_event(struct notifier_block *this, + unsigned long event, void *ptr) +{ + struct inet6_ifaddr *ifa = ptr; + const struct net_device *dev; + struct masq_dev_work *w; + struct net *net; + + if (event != NETDEV_DOWN || atomic_read(&v6_worker_count) >= 16) + return NOTIFY_DONE; + + dev = ifa->idev->dev; + net = maybe_get_net(dev_net(dev)); + if (!net) + return NOTIFY_DONE; + + if (!try_module_get(THIS_MODULE)) + goto err_module; + + w = kmalloc(sizeof(*w), GFP_ATOMIC); + if (w) { + atomic_inc(&v6_worker_count); + + INIT_WORK(&w->work, iterate_cleanup_work); + w->ifindex = dev->ifindex; + w->net = net; + w->addr = ifa->addr; + schedule_work(&w->work); + + return NOTIFY_DONE; + } + + module_put(THIS_MODULE); + err_module: + put_net(net); + return NOTIFY_DONE; +} + +static struct notifier_block masq_inet6_notifier = { + .notifier_call = masq_inet6_event, +}; + +int nf_nat_masquerade_ipv6_register_notifier(void) +{ + int ret = 0; + + mutex_lock(&masq_mutex); + /* check if the notifier is already set */ + if (++masq_refcnt > 1) + goto out_unlock; + + ret = register_netdevice_notifier(&masq_dev_notifier); + if (ret) + goto err_dec; + + ret = register_inet6addr_notifier(&masq_inet6_notifier); + if (ret) + goto err_unregister; + + mutex_unlock(&masq_mutex); + return ret; + +err_unregister: + unregister_netdevice_notifier(&masq_dev_notifier); +err_dec: + masq_refcnt--; +out_unlock: + mutex_unlock(&masq_mutex); + return ret; +} +EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_register_notifier); + +void nf_nat_masquerade_ipv6_unregister_notifier(void) +{ + mutex_lock(&masq_mutex); + /* check if the notifier still has clients */ + if (--masq_refcnt > 0) + goto out_unlock; + + unregister_inet6addr_notifier(&masq_inet6_notifier); + unregister_netdevice_notifier(&masq_dev_notifier); +out_unlock: + mutex_unlock(&masq_mutex); +} +EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_unregister_notifier); +#endif -- cgit v1.2.3