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authorDavid S. Miller <davem@davemloft.net>2019-05-30 14:18:18 -0700
committerDavid S. Miller <davem@davemloft.net>2019-05-30 14:18:18 -0700
commit41384136608c1cd6ef0ccb7d58d78775b2ddb035 (patch)
treeca54f38639e9f82bfd03b997ba4431884eeae790 /net/bridge
parentd48ecb40b5b5a156ae3658dc336bfc29ea502eb6 (diff)
parentaf9573be674e6aed893ad649c76d55c39a2f6420 (diff)
downloadlinux-41384136608c1cd6ef0ccb7d58d78775b2ddb035.tar.bz2
Merge branch 'connection-tracking-support-for-bridge'
Pablo Neira Ayuso says: ==================== connection tracking support for bridge This patchset adds native connection tracking support for the bridge. Patch #1 and #2 extract code from IPv4/IPv6 fragmentation core and introduce the fraglist splitter. That splits a skbuff fraglist into independent fragments. Patch #3 and #4 also extract code from IPv4/IPv6 fragmentation core and introduce the skbuff into fragments transformer. This can be used by linearized skbuffs (eg. coming from nfqueue and ct helpers) as well as cloned skbuffs (that are either seen either with taps or with bridge port flooding). Patch #5 moves the specific IPCB() code from these new fragment splitter/transformer APIs into the IPv4 stack. The bridge has a different control buffer layout and it starts using this new APIs in this patchset. Patch #6 adds basic infrastructure that allows to register bridge conntrack support. Patch #7 adds bridge conntrack support (only for IPv4 in this patch). Patch #8 adds IPv6 support for the bridge conntrack support. Patch #9 registers the IPv4/IPv6 conntrack hooks in case the bridge conntrack is used to deal with local traffic, ie. prerouting -> input bridge hook path. This cover the bridge interface has a IP address scenario. Before this patchset, only chance for people to do stateful filtering is to use the `br_netfilter` emulation layer, that turns bridge frame into IPv4/IPv6 packets and inject them into the IPv4/IPv6 hooks. Apparently, this module allows users to use iptables and all of its feature-set from the bridge, including stateful filtering. However, this approach is flawed in many aspects that have been discussed many times. This is a step forward to deprecate `br_netfilter'. v2: Fix English typo in commit message. v3: Fix another English typo in commit message. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/bridge')
-rw-r--r--net/bridge/br_device.c1
-rw-r--r--net/bridge/br_private.h1
-rw-r--r--net/bridge/netfilter/Kconfig14
-rw-r--r--net/bridge/netfilter/Makefile3
-rw-r--r--net/bridge/netfilter/nf_conntrack_bridge.c433
5 files changed, 452 insertions, 0 deletions
diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index 013323b6dbe4..693aefad7f8a 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -56,6 +56,7 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
br_switchdev_frame_unmark(skb);
BR_INPUT_SKB_CB(skb)->brdev = dev;
+ BR_INPUT_SKB_CB(skb)->frag_max_size = 0;
skb_reset_mac_header(skb);
eth = eth_hdr(skb);
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 334a8c496b50..68561741e827 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -425,6 +425,7 @@ struct net_bridge {
struct br_input_skb_cb {
struct net_device *brdev;
+ u16 frag_max_size;
#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
u8 igmp;
u8 mrouters_only:1;
diff --git a/net/bridge/netfilter/Kconfig b/net/bridge/netfilter/Kconfig
index c3ad90c43801..f4fb0b9b927d 100644
--- a/net/bridge/netfilter/Kconfig
+++ b/net/bridge/netfilter/Kconfig
@@ -19,6 +19,20 @@ config NF_LOG_BRIDGE
tristate "Bridge packet logging"
select NF_LOG_COMMON
+config NF_CONNTRACK_BRIDGE
+ tristate "IPv4/IPV6 bridge connection tracking support"
+ depends on NF_CONNTRACK
+ default n
+ help
+ Connection tracking keeps a record of what packets have passed
+ through your machine, in order to figure out how they are related
+ into connections. This is used to enhance packet filtering via
+ stateful policies. Enable this if you want native tracking from
+ the bridge. This provides a replacement for the `br_netfilter'
+ infrastructure.
+
+ To compile it as a module, choose M here. If unsure, say N.
+
endif # NF_TABLES_BRIDGE
menuconfig BRIDGE_NF_EBTABLES
diff --git a/net/bridge/netfilter/Makefile b/net/bridge/netfilter/Makefile
index 9b868861f21a..9d7767322a64 100644
--- a/net/bridge/netfilter/Makefile
+++ b/net/bridge/netfilter/Makefile
@@ -5,6 +5,9 @@
obj-$(CONFIG_NFT_BRIDGE_REJECT) += nft_reject_bridge.o
+# connection tracking
+obj-$(CONFIG_NF_CONNTRACK_BRIDGE) += nf_conntrack_bridge.o
+
# packet logging
obj-$(CONFIG_NF_LOG_BRIDGE) += nf_log_bridge.o
diff --git a/net/bridge/netfilter/nf_conntrack_bridge.c b/net/bridge/netfilter/nf_conntrack_bridge.c
new file mode 100644
index 000000000000..b675cd7c1a82
--- /dev/null
+++ b/net/bridge/netfilter/nf_conntrack_bridge.c
@@ -0,0 +1,433 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/types.h>
+#include <linux/ip.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv6.h>
+#include <linux/netfilter_bridge.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/icmp.h>
+#include <linux/sysctl.h>
+#include <net/route.h>
+#include <net/ip.h>
+
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_core.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_bridge.h>
+
+#include <linux/netfilter/nf_tables.h>
+#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
+#include <net/netfilter/nf_tables.h>
+
+#include "../br_private.h"
+
+/* Best effort variant of ip_do_fragment which preserves geometry, unless skbuff
+ * has been linearized or cloned.
+ */
+static int nf_br_ip_fragment(struct net *net, struct sock *sk,
+ struct sk_buff *skb,
+ struct nf_ct_bridge_frag_data *data,
+ int (*output)(struct net *, struct sock *sk,
+ const struct nf_ct_bridge_frag_data *data,
+ struct sk_buff *))
+{
+ int frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size;
+ unsigned int hlen, ll_rs, mtu;
+ struct ip_frag_state state;
+ struct iphdr *iph;
+ int err;
+
+ /* for offloaded checksums cleanup checksum before fragmentation */
+ if (skb->ip_summed == CHECKSUM_PARTIAL &&
+ (err = skb_checksum_help(skb)))
+ goto blackhole;
+
+ iph = ip_hdr(skb);
+
+ /*
+ * Setup starting values
+ */
+
+ hlen = iph->ihl * 4;
+ frag_max_size -= hlen;
+ ll_rs = LL_RESERVED_SPACE(skb->dev);
+ mtu = skb->dev->mtu;
+
+ if (skb_has_frag_list(skb)) {
+ unsigned int first_len = skb_pagelen(skb);
+ struct ip_fraglist_iter iter;
+ struct sk_buff *frag;
+
+ if (first_len - hlen > mtu ||
+ skb_headroom(skb) < ll_rs)
+ goto blackhole;
+
+ if (skb_cloned(skb))
+ goto slow_path;
+
+ skb_walk_frags(skb, frag) {
+ if (frag->len > mtu ||
+ skb_headroom(frag) < hlen + ll_rs)
+ goto blackhole;
+
+ if (skb_shared(frag))
+ goto slow_path;
+ }
+
+ ip_fraglist_init(skb, iph, hlen, &iter);
+
+ for (;;) {
+ if (iter.frag)
+ ip_fraglist_prepare(skb, &iter);
+
+ err = output(net, sk, data, skb);
+ if (err || !iter.frag)
+ break;
+
+ skb = ip_fraglist_next(&iter);
+ }
+ return err;
+ }
+slow_path:
+ /* This is a linearized skbuff, the original geometry is lost for us.
+ * This may also be a clone skbuff, we could preserve the geometry for
+ * the copies but probably not worth the effort.
+ */
+ ip_frag_init(skb, hlen, ll_rs, frag_max_size, &state);
+
+ while (state.left > 0) {
+ struct sk_buff *skb2;
+
+ skb2 = ip_frag_next(skb, &state);
+ if (IS_ERR(skb2)) {
+ err = PTR_ERR(skb2);
+ goto blackhole;
+ }
+
+ err = output(net, sk, data, skb2);
+ if (err)
+ goto blackhole;
+ }
+ consume_skb(skb);
+ return err;
+
+blackhole:
+ kfree_skb(skb);
+ return 0;
+}
+
+/* ip_defrag() expects IPCB() in place. */
+static void br_skb_cb_save(struct sk_buff *skb, struct br_input_skb_cb *cb,
+ size_t inet_skb_parm_size)
+{
+ memcpy(cb, skb->cb, sizeof(*cb));
+ memset(skb->cb, 0, inet_skb_parm_size);
+}
+
+static void br_skb_cb_restore(struct sk_buff *skb,
+ const struct br_input_skb_cb *cb,
+ u16 fragsz)
+{
+ memcpy(skb->cb, cb, sizeof(*cb));
+ BR_INPUT_SKB_CB(skb)->frag_max_size = fragsz;
+}
+
+static unsigned int nf_ct_br_defrag4(struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+ u16 zone_id = NF_CT_DEFAULT_ZONE_ID;
+ enum ip_conntrack_info ctinfo;
+ struct br_input_skb_cb cb;
+ const struct nf_conn *ct;
+ int err;
+
+ if (!ip_is_fragment(ip_hdr(skb)))
+ return NF_ACCEPT;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if (ct)
+ zone_id = nf_ct_zone_id(nf_ct_zone(ct), CTINFO2DIR(ctinfo));
+
+ br_skb_cb_save(skb, &cb, sizeof(struct inet_skb_parm));
+ local_bh_disable();
+ err = ip_defrag(state->net, skb,
+ IP_DEFRAG_CONNTRACK_BRIDGE_IN + zone_id);
+ local_bh_enable();
+ if (!err) {
+ br_skb_cb_restore(skb, &cb, IPCB(skb)->frag_max_size);
+ skb->ignore_df = 1;
+ return NF_ACCEPT;
+ }
+
+ return NF_STOLEN;
+}
+
+static unsigned int nf_ct_br_defrag6(struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+ u16 zone_id = NF_CT_DEFAULT_ZONE_ID;
+ enum ip_conntrack_info ctinfo;
+ struct br_input_skb_cb cb;
+ const struct nf_conn *ct;
+ int err;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if (ct)
+ zone_id = nf_ct_zone_id(nf_ct_zone(ct), CTINFO2DIR(ctinfo));
+
+ br_skb_cb_save(skb, &cb, sizeof(struct inet6_skb_parm));
+
+ err = nf_ipv6_br_defrag(state->net, skb,
+ IP_DEFRAG_CONNTRACK_BRIDGE_IN + zone_id);
+ /* queued */
+ if (err == -EINPROGRESS)
+ return NF_STOLEN;
+
+ br_skb_cb_restore(skb, &cb, IP6CB(skb)->frag_max_size);
+ return err == 0 ? NF_ACCEPT : NF_DROP;
+}
+
+static int nf_ct_br_ip_check(const struct sk_buff *skb)
+{
+ const struct iphdr *iph;
+ int nhoff, len;
+
+ nhoff = skb_network_offset(skb);
+ iph = ip_hdr(skb);
+ if (iph->ihl < 5 ||
+ iph->version != 4)
+ return -1;
+
+ len = ntohs(iph->tot_len);
+ if (skb->len < nhoff + len ||
+ len < (iph->ihl * 4))
+ return -1;
+
+ return 0;
+}
+
+static int nf_ct_br_ipv6_check(const struct sk_buff *skb)
+{
+ const struct ipv6hdr *hdr;
+ int nhoff, len;
+
+ nhoff = skb_network_offset(skb);
+ hdr = ipv6_hdr(skb);
+ if (hdr->version != 6)
+ return -1;
+
+ len = ntohs(hdr->payload_len) + sizeof(struct ipv6hdr) + nhoff;
+ if (skb->len < len)
+ return -1;
+
+ return 0;
+}
+
+static unsigned int nf_ct_bridge_pre(void *priv, struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+ struct nf_hook_state bridge_state = *state;
+ enum ip_conntrack_info ctinfo;
+ struct nf_conn *ct;
+ u32 len;
+ int ret;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if ((ct && !nf_ct_is_template(ct)) ||
+ ctinfo == IP_CT_UNTRACKED)
+ return NF_ACCEPT;
+
+ switch (skb->protocol) {
+ case htons(ETH_P_IP):
+ if (!pskb_may_pull(skb, sizeof(struct iphdr)))
+ return NF_ACCEPT;
+
+ len = ntohs(ip_hdr(skb)->tot_len);
+ if (pskb_trim_rcsum(skb, len))
+ return NF_ACCEPT;
+
+ if (nf_ct_br_ip_check(skb))
+ return NF_ACCEPT;
+
+ bridge_state.pf = NFPROTO_IPV4;
+ ret = nf_ct_br_defrag4(skb, &bridge_state);
+ break;
+ case htons(ETH_P_IPV6):
+ if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
+ return NF_ACCEPT;
+
+ len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
+ if (pskb_trim_rcsum(skb, len))
+ return NF_ACCEPT;
+
+ if (nf_ct_br_ipv6_check(skb))
+ return NF_ACCEPT;
+
+ bridge_state.pf = NFPROTO_IPV6;
+ ret = nf_ct_br_defrag6(skb, &bridge_state);
+ break;
+ default:
+ nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
+ return NF_ACCEPT;
+ }
+
+ if (ret != NF_ACCEPT)
+ return ret;
+
+ return nf_conntrack_in(skb, &bridge_state);
+}
+
+static void nf_ct_bridge_frag_save(struct sk_buff *skb,
+ struct nf_ct_bridge_frag_data *data)
+{
+ if (skb_vlan_tag_present(skb)) {
+ data->vlan_present = true;
+ data->vlan_tci = skb->vlan_tci;
+ data->vlan_proto = skb->vlan_proto;
+ } else {
+ data->vlan_present = false;
+ }
+ skb_copy_from_linear_data_offset(skb, -ETH_HLEN, data->mac, ETH_HLEN);
+}
+
+static unsigned int
+nf_ct_bridge_refrag(struct sk_buff *skb, const struct nf_hook_state *state,
+ int (*output)(struct net *, struct sock *sk,
+ const struct nf_ct_bridge_frag_data *data,
+ struct sk_buff *))
+{
+ struct nf_ct_bridge_frag_data data;
+
+ if (!BR_INPUT_SKB_CB(skb)->frag_max_size)
+ return NF_ACCEPT;
+
+ nf_ct_bridge_frag_save(skb, &data);
+ switch (skb->protocol) {
+ case htons(ETH_P_IP):
+ nf_br_ip_fragment(state->net, state->sk, skb, &data, output);
+ break;
+ case htons(ETH_P_IPV6):
+ nf_br_ip6_fragment(state->net, state->sk, skb, &data, output);
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ return NF_DROP;
+ }
+
+ return NF_STOLEN;
+}
+
+/* Actually only slow path refragmentation needs this. */
+static int nf_ct_bridge_frag_restore(struct sk_buff *skb,
+ const struct nf_ct_bridge_frag_data *data)
+{
+ int err;
+
+ err = skb_cow_head(skb, ETH_HLEN);
+ if (err) {
+ kfree_skb(skb);
+ return -ENOMEM;
+ }
+ if (data->vlan_present)
+ __vlan_hwaccel_put_tag(skb, data->vlan_proto, data->vlan_tci);
+
+ skb_copy_to_linear_data_offset(skb, -ETH_HLEN, data->mac, ETH_HLEN);
+ skb_reset_mac_header(skb);
+
+ return 0;
+}
+
+static int nf_ct_bridge_refrag_post(struct net *net, struct sock *sk,
+ const struct nf_ct_bridge_frag_data *data,
+ struct sk_buff *skb)
+{
+ int err;
+
+ err = nf_ct_bridge_frag_restore(skb, data);
+ if (err < 0)
+ return err;
+
+ return br_dev_queue_push_xmit(net, sk, skb);
+}
+
+static unsigned int nf_ct_bridge_confirm(struct sk_buff *skb)
+{
+ enum ip_conntrack_info ctinfo;
+ struct nf_conn *ct;
+ int protoff;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if (!ct || ctinfo == IP_CT_RELATED_REPLY)
+ return nf_conntrack_confirm(skb);
+
+ switch (skb->protocol) {
+ case htons(ETH_P_IP):
+ protoff = skb_network_offset(skb) + ip_hdrlen(skb);
+ break;
+ case htons(ETH_P_IPV6): {
+ unsigned char pnum = ipv6_hdr(skb)->nexthdr;
+ __be16 frag_off;
+
+ protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &pnum,
+ &frag_off);
+ if (protoff < 0 || (frag_off & htons(~0x7)) != 0)
+ return nf_conntrack_confirm(skb);
+ }
+ break;
+ default:
+ return NF_ACCEPT;
+ }
+ return nf_confirm(skb, protoff, ct, ctinfo);
+}
+
+static unsigned int nf_ct_bridge_post(void *priv, struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+ int ret;
+
+ ret = nf_ct_bridge_confirm(skb);
+ if (ret != NF_ACCEPT)
+ return ret;
+
+ return nf_ct_bridge_refrag(skb, state, nf_ct_bridge_refrag_post);
+}
+
+static struct nf_hook_ops nf_ct_bridge_hook_ops[] __read_mostly = {
+ {
+ .hook = nf_ct_bridge_pre,
+ .pf = NFPROTO_BRIDGE,
+ .hooknum = NF_BR_PRE_ROUTING,
+ .priority = NF_IP_PRI_CONNTRACK,
+ },
+ {
+ .hook = nf_ct_bridge_post,
+ .pf = NFPROTO_BRIDGE,
+ .hooknum = NF_BR_POST_ROUTING,
+ .priority = NF_IP_PRI_CONNTRACK_CONFIRM,
+ },
+};
+
+static struct nf_ct_bridge_info bridge_info = {
+ .ops = nf_ct_bridge_hook_ops,
+ .ops_size = ARRAY_SIZE(nf_ct_bridge_hook_ops),
+ .me = THIS_MODULE,
+};
+
+static int __init nf_conntrack_l3proto_bridge_init(void)
+{
+ nf_ct_bridge_register(&bridge_info);
+
+ return 0;
+}
+
+static void __exit nf_conntrack_l3proto_bridge_fini(void)
+{
+ nf_ct_bridge_unregister(&bridge_info);
+}
+
+module_init(nf_conntrack_l3proto_bridge_init);
+module_exit(nf_conntrack_l3proto_bridge_fini);
+
+MODULE_ALIAS("nf_conntrack-" __stringify(AF_BRIDGE));
+MODULE_LICENSE("GPL");