lkml.org 
[lkml]   [2012]   [Jan]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[patch v7, kernel version 3.2.1] net/ipv4/ip_gre: Ethernet multipoint GRE over IP
From: Stefan Gula <steweg@gmail.com>

This patch is an extension for current Ethernet over GRE
implementation, which allows user to create virtual bridge (multipoint
VPN) and forward traffic based on Ethernet MAC address information in
it. It simulates the Bridge behavior learning mechanism, but instead
of learning port ID from which given MAC address comes, it learns IP
address of peer which encapsulated given packet. Multicast, Broadcast
and unknown-multicast traffic is send over network as multicast
encapsulated GRE packet, so one Ethernet multipoint GRE tunnel can be
represented as one single virtual switch on logical level and be also
represented as one multicast IPv4 address on network level.

Signed-off-by: Stefan Gula <steweg@gmail.com>


---

V6&7 changes:
- added "[no]bridge" netlink option to enable or disable the behavior
based on configuration rather then using only kernel option. Example
of such link creation:
ip link add VPN1 type gretap local 10.1.1.1 remote 239.192.0.1 key
12345 ttl 5 nopmtu bridge
- Default value is "nobridge"
- This provides backward compatibility with any previous installations
- run flush function after interface moved from "bridge" to "nobridge"
behavior

Before you decline this please consider the things below:
Reasons for adding this to kernel directly instead of openvswitch code:
- neither NVGRE nor VXLAN are part of the openvswitch for now
- NVGRE is even not yet fully standardized. Missing info how the mapping table will
be build -> new RFC is expected for this
- VXLAN uses always header of size 16B (8B VXLAN header + 8B UDP header)
- openvswitch doesn't implement ebtables/arptables/iptables rules
properly, so if one wanted to use this in combinations it needs
original bridge code, which would be somehow connected to openvswitch
- e.g. using veth module between them
This brings 3 lookups (original bridge, openvswitch bridge and gre
internal bridge) instead of only 2 (original bridge and bridge
inside the gretap interface) resulting apparently in non optimal
performance.
- e.g. in my scenario linux-based APs uses ebtables, iptables and
arptables to prevent ARP spoofing, DHCP spoofing, IP spoofing, and
do some mangling staff like NATting of some mac-addresses...

- My patch uses headers of size from 8B to 20B (depends on configuration)
- possible less fragmentation needed in contrast to VXLAN
- methodology of learning VXLAN and my patch is almost the same - my is
only missing mapping of inner multicast groups to outside multicast
addresses. VXLAN relies on controller to define that, my is limited for
using only one multicast address for all inner multicasts
- adding "bridge" keyword make this patch stable and backward compatible
- fully compatible with any kind of filtering/mangling needed based on
standard linux network stack (excluding filtering inside the gretap
bridge itself)

Summary:
- OpenVswitch is apparently good solution for virtualization deployments
where network security is done on separate devices or not needed at all,
but currently lacks several security aspects to be fully ready to
replace the original bridge code in non virtualized environments, where
the boxes implement also network security features like linux based APs.
I believe that such major changes should be driven by some maintainer of
openvswitch rather than myself.

Patch V7:

diff -uprN -X linux-3.2.1-orig/Documentation/dontdiff linux-3.2.1-orig/include/linux/if_tunnel.h linux/include/linux/if_tunnel.h
--- linux-3.2.1-orig/include/linux/if_tunnel.h 2012-01-27 13:38:56.000000000 +0000
+++ linux/include/linux/if_tunnel.h 2012-01-30 14:10:01.000000000 +0000
@@ -75,6 +75,7 @@ enum {
IFLA_GRE_TTL,
IFLA_GRE_TOS,
IFLA_GRE_PMTUDISC,
+ IFLA_GRE_BRIDGE,
__IFLA_GRE_MAX,
};

diff -uprN -X linux-3.2.1-orig/Documentation/dontdiff linux-3.2.1-orig/include/net/ipip.h linux/include/net/ipip.h
--- linux-3.2.1-orig/include/net/ipip.h 2012-01-27 13:38:57.000000000 +0000
+++ linux/include/net/ipip.h 2012-01-30 14:10:01.000000000 +0000
@@ -27,6 +27,15 @@ struct ip_tunnel {
__u32 o_seqno; /* The last output seqno */
int hlen; /* Precalculated GRE header length */
int mlink;
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+#define GRETAP_BR_HASH_BITS 8
+#define GRETAP_BR_HASH_SIZE (1 << GRETAP_BR_HASH_BITS)
+ struct hlist_head hash[GRETAP_BR_HASH_SIZE];
+ spinlock_t hash_lock;
+ unsigned long ageing_time;
+ struct timer_list gc_timer;
+ bool br_enabled;
+#endif

struct ip_tunnel_parm parms;

diff -uprN -X linux-3.2.1-orig/Documentation/dontdiff linux-3.2.1-orig/net/ipv4/Kconfig linux/net/ipv4/Kconfig
--- linux-3.2.1-orig/net/ipv4/Kconfig 2012-01-27 13:39:00.000000000 +0000
+++ linux/net/ipv4/Kconfig 2012-01-30 14:10:01.000000000 +0000
@@ -211,6 +211,15 @@ config NET_IPGRE_BROADCAST
Network), but can be distributed all over the Internet. If you want
to do that, say Y here and to "IP multicast routing" below.

+config NET_IPGRE_BRIDGE
+ bool "IP: Ethernet over multipoint GRE over IP"
+ depends on IP_MULTICAST && NET_IPGRE && NET_IPGRE_BROADCAST
+ help
+ Allows you to use multipoint GRE VPN as virtual switch and interconnect
+ several L2 endpoints over L3 routed infrastructure. It is useful for
+ creating multipoint L2 VPNs which can be later used inside bridge
+ interfaces If you want to use. GRE multipoint L2 VPN feature say Y.
+
config IP_MROUTE
bool "IP: multicast routing"
depends on IP_MULTICAST
diff -uprN -X linux-3.2.1-orig/Documentation/dontdiff linux-3.2.1-orig/net/ipv4/ip_gre.c linux/net/ipv4/ip_gre.c
--- linux-3.2.1-orig/net/ipv4/ip_gre.c 2012-01-27 13:39:00.000000000 +0000
+++ linux/net/ipv4/ip_gre.c 2012-01-30 15:10:35.000000000 +0000
@@ -52,6 +52,11 @@
#include <net/ip6_route.h>
#endif

+#ifdef CONFIG_NET_IPGRE_BRIDGE
+#include <linux/jhash.h>
+#include <asm/unaligned.h>
+#endif
+
/*
Problems & solutions
--------------------
@@ -134,6 +139,203 @@ struct ipgre_net {
struct net_device *fb_tunnel_dev;
};

+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ /*
+ * This part of code includes codes to enable L2 ethernet
+ * switch virtualization over IP routed infrastructure with
+ * utilization of multicast capable endpoint using Ethernet
+ * over GRE
+ *
+ * Author: Stefan Gula
+ * Signed-off-by: Stefan Gula <steweg@gmail.com>
+ */
+struct ipgre_tap_bridge_entry {
+ struct hlist_node hlist;
+ __be32 raddr;
+ unsigned char addr[ETH_ALEN];
+ unsigned long updated;
+ struct rcu_head rcu;
+};
+
+static u32 ipgre_salt __read_mostly;
+
+static inline int ipgre_tap_bridge_hash(const unsigned char *mac)
+{
+ u32 key = get_unaligned((u32 *)(mac + 2));
+
+ return jhash_1word(key, ipgre_salt) & (GRETAP_BR_HASH_SIZE - 1);
+}
+
+static inline int ipgre_tap_bridge_has_expired(const struct ip_tunnel *tunnel,
+ const struct ipgre_tap_bridge_entry *entry)
+{
+ return time_before_eq(entry->updated + tunnel->ageing_time,
+ jiffies);
+}
+
+static inline void ipgre_tap_bridge_delete(struct ipgre_tap_bridge_entry *entry)
+{
+ hlist_del_rcu(&entry->hlist);
+ kfree_rcu(entry, rcu);
+}
+
+static void ipgre_tap_bridge_cleanup(unsigned long _data)
+{
+ struct ip_tunnel *tunnel = (struct ip_tunnel *)_data;
+ unsigned long delay = tunnel->ageing_time;
+ unsigned long next_timer = jiffies + tunnel->ageing_time;
+ int i;
+
+ spin_lock(&tunnel->hash_lock);
+ for (i = 0; i < GRETAP_BR_HASH_SIZE; i++) {
+ struct ipgre_tap_bridge_entry *entry;
+ struct hlist_node *h, *n;
+
+ hlist_for_each_entry_safe(entry, h, n,
+ &tunnel->hash[i], hlist)
+ {
+ unsigned long this_timer;
+ this_timer = entry->updated + delay;
+ if (time_before_eq(this_timer, jiffies))
+ ipgre_tap_bridge_delete(entry);
+ else if (time_before(this_timer, next_timer))
+ next_timer = this_timer;
+ }
+ }
+ spin_unlock(&tunnel->hash_lock);
+ mod_timer(&tunnel->gc_timer, round_jiffies_up(next_timer));
+}
+
+static void ipgre_tap_bridge_flush(struct ip_tunnel *tunnel)
+{
+ int i;
+
+ spin_lock_bh(&tunnel->hash_lock);
+ for (i = 0; i < GRETAP_BR_HASH_SIZE; i++) {
+ struct ipgre_tap_bridge_entry *entry;
+ struct hlist_node *h, *n;
+
+ hlist_for_each_entry_safe(entry, h, n,
+ &tunnel->hash[i], hlist)
+ {
+ ipgre_tap_bridge_delete(entry);
+ }
+ }
+ spin_unlock_bh(&tunnel->hash_lock);
+}
+
+static struct ipgre_tap_bridge_entry *__ipgre_tap_bridge_get(
+ struct ip_tunnel *tunnel, const unsigned char *addr)
+{
+ struct hlist_node *h;
+ struct ipgre_tap_bridge_entry *entry;
+
+ hlist_for_each_entry_rcu(entry, h,
+ &tunnel->hash[ipgre_tap_bridge_hash(addr)], hlist) {
+ if (!compare_ether_addr(entry->addr, addr)) {
+ if (unlikely(ipgre_tap_bridge_has_expired(tunnel,
+ entry)))
+ break;
+ return entry;
+ }
+ }
+
+ return NULL;
+}
+
+static struct ipgre_tap_bridge_entry *ipgre_tap_bridge_find(
+ struct hlist_head *head,
+ const unsigned char *addr)
+{
+ struct hlist_node *h;
+ struct ipgre_tap_bridge_entry *entry;
+
+ hlist_for_each_entry(entry, h, head, hlist) {
+ if (!compare_ether_addr(entry->addr, addr))
+ return entry;
+ }
+ return NULL;
+}
+
+
+static struct ipgre_tap_bridge_entry *ipgre_tap_bridge_find_rcu(
+ struct hlist_head *head,
+ const unsigned char *addr)
+{
+ struct hlist_node *h;
+ struct ipgre_tap_bridge_entry *entry;
+
+ hlist_for_each_entry_rcu(entry, h, head, hlist) {
+ if (!compare_ether_addr(entry->addr, addr))
+ return entry;
+ }
+ return NULL;
+}
+
+static struct ipgre_tap_bridge_entry *ipgre_tap_bridge_create(
+ struct hlist_head *head,
+ __be32 source,
+ const unsigned char *addr)
+{
+ struct ipgre_tap_bridge_entry *entry;
+
+ entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
+ if (entry) {
+ memcpy(entry->addr, addr, ETH_ALEN);
+ entry->raddr = source;
+ entry->updated = jiffies;
+ hlist_add_head_rcu(&entry->hlist, head);
+ }
+ return entry;
+}
+
+static __be32 ipgre_tap_bridge_get_raddr(struct ip_tunnel *tunnel,
+ const unsigned char *addr)
+{
+ __be32 raddr = 0;
+ struct ipgre_tap_bridge_entry *entry;
+
+ rcu_read_lock();
+ entry = __ipgre_tap_bridge_get(tunnel, addr);
+ if (entry)
+ raddr = entry->raddr;
+ rcu_read_unlock();
+
+ return raddr;
+}
+
+static void ipgre_tap_bridge_rcv(struct ip_tunnel *tunnel,
+ struct sk_buff *skb,
+ __be32 orig_source)
+{
+ const struct ethhdr *tethhdr;
+ struct hlist_head *head;
+ struct ipgre_tap_bridge_entry *entry;
+
+ if (ipv4_is_multicast(tunnel->parms.iph.daddr)) {
+ tethhdr = eth_hdr(skb);
+ if (!is_multicast_ether_addr(
+ tethhdr->h_source)) {
+ head = &tunnel->hash[
+ ipgre_tap_bridge_hash(tethhdr->h_source)];
+ entry = ipgre_tap_bridge_find_rcu(head,
+ tethhdr->h_source);
+ if (likely(entry)) {
+ entry->raddr = orig_source;
+ entry->updated = jiffies;
+ } else {
+ spin_lock(&tunnel->hash_lock);
+ if (!ipgre_tap_bridge_find(head,
+ tethhdr->h_source))
+ ipgre_tap_bridge_create(head,
+ orig_source,
+ tethhdr->h_source);
+ spin_unlock(&tunnel->hash_lock);
+ }
+ }
+ }
+}
+#endif
/* Tunnel hash table */

/*
@@ -562,6 +764,9 @@ static int ipgre_rcv(struct sk_buff *skb
struct ip_tunnel *tunnel;
int offset = 4;
__be16 gre_proto;
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ __be32 orig_source;
+#endif

if (!pskb_may_pull(skb, 16))
goto drop_nolock;
@@ -654,6 +859,9 @@ static int ipgre_rcv(struct sk_buff *skb

/* Warning: All skb pointers will be invalidated! */
if (tunnel->dev->type == ARPHRD_ETHER) {
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ orig_source = iph->saddr;
+#endif
if (!pskb_may_pull(skb, ETH_HLEN)) {
tunnel->dev->stats.rx_length_errors++;
tunnel->dev->stats.rx_errors++;
@@ -663,6 +871,10 @@ static int ipgre_rcv(struct sk_buff *skb
iph = ip_hdr(skb);
skb->protocol = eth_type_trans(skb, tunnel->dev);
skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ if (tunnel->br_enabled)
+ ipgre_tap_bridge_rcv(tunnel, skb, orig_source);
+#endif
}

tstats = this_cpu_ptr(tunnel->dev->tstats);
@@ -702,7 +914,7 @@ static netdev_tx_t ipgre_tunnel_xmit(str
struct iphdr *iph; /* Our new IP header */
unsigned int max_headroom; /* The extra header space needed */
int gre_hlen;
- __be32 dst;
+ __be32 dst = 0;
int mtu;

if (dev->type == ARPHRD_ETHER)
@@ -716,7 +928,15 @@ static netdev_tx_t ipgre_tunnel_xmit(str
tiph = &tunnel->parms.iph;
}

- if ((dst = tiph->daddr) == 0) {
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ if (tunnel->br_enabled && (dev->type == ARPHRD_ETHER) &&
+ ipv4_is_multicast(tunnel->parms.iph.daddr))
+ dst = ipgre_tap_bridge_get_raddr(tunnel,
+ ((struct ethhdr *)skb->data)->h_dest);
+#endif
+ if (dst == 0)
+ dst = tiph->daddr;
+ if (dst == 0) {
/* NBMA tunnel */

if (skb_dst(skb) == NULL) {
@@ -1209,6 +1429,16 @@ static int ipgre_open(struct net_device
return -EADDRNOTAVAIL;
t->mlink = dev->ifindex;
ip_mc_inc_group(__in_dev_get_rtnl(dev), t->parms.iph.daddr);
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ if (t->dev->type == ARPHRD_ETHER) {
+ INIT_HLIST_HEAD(t->hash);
+ spin_lock_init(&t->hash_lock);
+ t->ageing_time = 300 * HZ;
+ setup_timer(&t->gc_timer, ipgre_tap_bridge_cleanup,
+ (unsigned long) t);
+ mod_timer(&t->gc_timer, jiffies + t->ageing_time);
+ }
+#endif
}
return 0;
}
@@ -1219,6 +1449,12 @@ static int ipgre_close(struct net_device

if (ipv4_is_multicast(t->parms.iph.daddr) && t->mlink) {
struct in_device *in_dev;
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ if (t->dev->type == ARPHRD_ETHER) {
+ ipgre_tap_bridge_flush(t);
+ del_timer_sync(&t->gc_timer);
+ }
+#endif
in_dev = inetdev_by_index(dev_net(dev), t->mlink);
if (in_dev)
ip_mc_dec_group(in_dev, t->parms.iph.daddr);
@@ -1488,6 +1724,10 @@ static int ipgre_tap_init(struct net_dev
static const struct net_device_ops ipgre_tap_netdev_ops = {
.ndo_init = ipgre_tap_init,
.ndo_uninit = ipgre_tunnel_uninit,
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ .ndo_open = ipgre_open,
+ .ndo_stop = ipgre_close,
+#endif
.ndo_start_xmit = ipgre_tunnel_xmit,
.ndo_set_mac_address = eth_mac_addr,
.ndo_validate_addr = eth_validate_addr,
@@ -1532,6 +1772,13 @@ static int ipgre_newlink(struct net *src
/* Can use a lockless transmit, unless we generate output sequences */
if (!(nt->parms.o_flags & GRE_SEQ))
dev->features |= NETIF_F_LLTX;
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ if (data && (!data[IFLA_GRE_BRIDGE] ||
+ nla_get_u8(data[IFLA_GRE_BRIDGE])))
+ nt->br_enabled = true;
+ else
+ nt->br_enabled = false;
+#endif

err = register_netdevice(dev);
if (err)
@@ -1588,6 +1835,16 @@ static int ipgre_changelink(struct net_d
memcpy(dev->dev_addr, &p.iph.saddr, 4);
memcpy(dev->broadcast, &p.iph.daddr, 4);
}
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ if (data && (!data[IFLA_GRE_BRIDGE] ||
+ nla_get_u8(data[IFLA_GRE_BRIDGE]))) {
+ t->br_enabled = true;
+ } else {
+ if(t->br_enabled)
+ ipgre_tap_bridge_flush(t);
+ t->br_enabled = false;
+ }
+#endif
ipgre_tunnel_link(ign, t);
netdev_state_change(dev);
}
@@ -1629,8 +1886,12 @@ static size_t ipgre_get_size(const struc
nla_total_size(1) +
/* IFLA_GRE_TOS */
nla_total_size(1) +
- /* IFLA_GRE_PMTUDISC */
+ /* IFLA_GREPMTUDISC */
nla_total_size(1) +
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ /* IFLA_GRE_BRIDGE */
+ nla_total_size(1) +
+#endif
0;
}

@@ -1649,7 +1910,9 @@ static int ipgre_fill_info(struct sk_buf
NLA_PUT_U8(skb, IFLA_GRE_TTL, p->iph.ttl);
NLA_PUT_U8(skb, IFLA_GRE_TOS, p->iph.tos);
NLA_PUT_U8(skb, IFLA_GRE_PMTUDISC, !!(p->iph.frag_off & htons(IP_DF)));
-
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ NLA_PUT_U8(skb, IFLA_GRE_BRIDGE, t->br_enabled);
+#endif
return 0;

nla_put_failure:
@@ -1667,6 +1930,7 @@ static const struct nla_policy ipgre_pol
[IFLA_GRE_TTL] = { .type = NLA_U8 },
[IFLA_GRE_TOS] = { .type = NLA_U8 },
[IFLA_GRE_PMTUDISC] = { .type = NLA_U8 },
+ [IFLA_GRE_BRIDGE] = { .type = NLA_U8 },
};

static struct rtnl_link_ops ipgre_link_ops __read_mostly = {
@@ -1705,6 +1969,9 @@ static int __init ipgre_init(void)

printk(KERN_INFO "GRE over IPv4 tunneling driver\n");

+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ get_random_bytes(&ipgre_salt, sizeof(ipgre_salt));
+#endif
err = register_pernet_device(&ipgre_net_ops);
if (err < 0)
return err;









\
 
 \ /
  Last update: 2012-01-31 14:27    [W:0.072 / U:0.080 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site