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[patch v1, kernel version 3.2.1] net/ipv4/ip_gre: Ethernet multipoint GRE over IP

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Štefan Gula

unread,
Jan 16, 2012, 7:20:02 AM1/16/12
to
From: Stefan Gula <ste...@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 informations in
it. It simulates the Bridge bahaviour learing 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
enacapsulated 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 <ste...@gmail.com>

---

Patch was tested for more than one year in real network infrastructure
consisting of 98 Linux based access-points

diff -uprN -X linux-3.2.1-orig/Documentation/dontdiff
linux-3.2.1-orig/Documentation/dontdiff
linux-3.2.1-my/Documentation/dontdiff
--- linux-3.2.1-orig/Documentation/dontdiff 2012-01-16 12:32:18.000000000 +0100
+++ linux-3.2.1-my/Documentation/dontdiff 2012-01-12 20:42:45.000000000 +0100
@@ -260,5 +260,3 @@ wakeup.lds
zImage*
zconf.hash.c
zoffset.h
-mkpiggy
-mdp
diff -uprN -X linux-3.2.1-orig/Documentation/dontdiff
linux-3.2.1-orig/include/net/ipip.h linux-3.2.1-my/include/net/ipip.h
--- linux-3.2.1-orig/include/net/ipip.h 2012-01-12 20:42:45.000000000 +0100
+++ linux-3.2.1-my/include/net/ipip.h 2012-01-16 11:17:01.000000000 +0100
@@ -27,6 +27,14 @@ 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;
+#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-3.2.1-my/net/ipv4/Kconfig
--- linux-3.2.1-orig/net/ipv4/Kconfig 2012-01-12 20:42:45.000000000 +0100
+++ linux-3.2.1-my/net/ipv4/Kconfig 2012-01-16 12:37:00.000000000 +0100
@@ -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-3.2.1-my/net/ipv4/ip_gre.c
--- linux-3.2.1-orig/net/ipv4/ip_gre.c 2012-01-12 20:42:45.000000000 +0100
+++ linux-3.2.1-my/net/ipv4/ip_gre.c 2012-01-16 12:29:03.000000000 +0100
@@ -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 +139,199 @@ 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 <ste...@gmail.com>
+ */
+struct mac_addr {
+ unsigned char addr[6];
+};
+
+struct ipgre_tap_bridge_entry {
+ struct hlist_node hlist;
+ u32 raddr;
+ struct mac_addr addr;
+ struct net_device *dev;
+ struct rcu_head rcu;
+ atomic_t use_count;
+ unsigned long ageing_timer;
+};
+
+static struct kmem_cache *ipgre_tap_bridge_cache __read_mostly;
+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->ageing_timer + tunnel->ageing_time,
+ jiffies);
+}
+
+static void ipgre_tap_bridge_rcu_free(struct rcu_head *head)
+{
+ struct ipgre_tap_bridge_entry *entry
+ = container_of(head, struct ipgre_tap_bridge_entry, rcu);
+ kmem_cache_free(ipgre_tap_bridge_cache, entry);
+}
+
+void ipgre_tap_bridge_put(struct ipgre_tap_bridge_entry *entry)
+{
+ if (atomic_dec_and_test(&entry->use_count))
+ call_rcu(&entry->rcu, ipgre_tap_bridge_rcu_free);
+}
+
+static inline void ipgre_tap_bridge_delete(struct
ipgre_tap_bridge_entry *entry)
+{
+ hlist_del_rcu(&entry->hlist);
+ ipgre_tap_bridge_put(entry);
+}
+
+static struct ipgre_tap_bridge_entry *ipgre_tap_bridge_create(
+ struct hlist_head *head,
+ u32 source,
+ const unsigned char *addr, struct net_device *dev)
+{
+ struct ipgre_tap_bridge_entry *entry;
+ entry = kmem_cache_alloc(ipgre_tap_bridge_cache, GFP_ATOMIC);
+ if (entry) {
+ memcpy(entry->addr.addr, addr, ETH_ALEN);
+ atomic_set(&entry->use_count, 1);
+ hlist_add_head_rcu(&entry->hlist, head);
+ entry->raddr = source;
+ entry->ageing_timer = jiffies;
+ entry->dev = dev;
+ }
+ return entry;
+}
+
+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, addr)) {
+ if (unlikely(ipgre_tap_bridge_has_expired(tunnel,
+ entry)))
+ break;
+ return entry;
+ }
+ }
+
+ return NULL;
+}
+
+struct ipgre_tap_bridge_entry *ipgre_tap_bridge_get(struct ip_tunnel *tunnel,
+ const unsigned char *addr)
+{
+ struct ipgre_tap_bridge_entry *entry;
+ rcu_read_lock();
+ entry = __ipgre_tap_bridge_get(tunnel, addr);
+ if (entry && !atomic_inc_not_zero(&entry->use_count))
+ entry = NULL;
+ rcu_read_unlock();
+ return entry;
+}
+
+__be32 ipgre_tap_bridge_get_raddr(struct ip_tunnel *tunnel,
+ const unsigned char *addr)
+{
+ struct ipgre_tap_bridge_entry *entry;
+ entry = ipgre_tap_bridge_get(tunnel, addr);
+ if (entry == NULL)
+ return 0;
+ else
+ return entry->raddr;
+}
+
+
+static inline 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_rcu(entry, h, head, hlist) {
+ if (!compare_ether_addr(entry->addr.addr, addr))
+ return entry;
+ }
+ return NULL;
+}
+
+int ipgre_tap_bridge_init(void)
+{
+ ipgre_tap_bridge_cache = kmem_cache_create("ipgre_tap_bridge_cache",
+ sizeof(struct ipgre_tap_bridge_entry),
+ 0,
+ SLAB_HWCACHE_ALIGN, NULL);
+ if (!ipgre_tap_bridge_cache)
+ return -ENOMEM;
+ get_random_bytes(&ipgre_salt, sizeof(ipgre_salt));
+ return 0;
+}
+
+void ipgre_tap_bridge_fini(void)
+{
+ kmem_cache_destroy(ipgre_tap_bridge_cache);
+}
+
+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_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)
+ {
+ unsigned long this_timer;
+ this_timer = entry->ageing_timer + 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_bh(&tunnel->hash_lock);
+ mod_timer(&tunnel->gc_timer, round_jiffies(next_timer + HZ/4));
+}
+
+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);
+}
+
+#endif
+
/* Tunnel hash table */

/*
@@ -563,6 +761,13 @@ static int ipgre_rcv(struct sk_buff *skb
int offset = 4;
__be16 gre_proto;

+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ u32 orig_source;
+ struct hlist_head *head;
+ struct ipgre_tap_bridge_entry *entry;
+ struct ethhdr *tethhdr;
+#endif
+
if (!pskb_may_pull(skb, 16))
goto drop_nolock;

@@ -659,10 +864,38 @@ static int ipgre_rcv(struct sk_buff *skb
tunnel->dev->stats.rx_errors++;
goto drop;
}
-
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ orig_source = iph->saddr;
+#endif
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 (ipv4_is_multicast(tunnel->parms.iph.daddr)) {
+ tethhdr = eth_hdr(skb);
+ if ((tethhdr->h_source[0]&1) == 0) {
+ head = &tunnel->hash[
+ ipgre_tap_bridge_hash(
+ tethhdr->h_source)];
+ entry = ipgre_tap_bridge_find(head,
+ tethhdr->h_source);
+ if (likely(entry)) {
+ entry->raddr = orig_source;
+ entry->ageing_timer = 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,
+ tunnel->dev);
+ spin_unlock(&tunnel->hash_lock);
+ }
+ }
+ }
+#endif
}

tstats = this_cpu_ptr(tunnel->dev->tstats);
@@ -716,7 +949,17 @@ static netdev_tx_t ipgre_tunnel_xmit(str
tiph = &tunnel->parms.iph;
}

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

if (skb_dst(skb) == NULL) {
@@ -1209,6 +1452,16 @@ 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 +1472,12 @@ 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);
@@ -1341,6 +1600,12 @@ static int __net_init ipgre_init_net(str
struct ipgre_net *ign = net_generic(net, ipgre_net_id);
int err;

+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ err = ipgre_tap_bridge_init();
+ if (err)
+ goto err_out;
+#endif
+
ign->fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "gre0",
ipgre_tunnel_setup);
if (!ign->fb_tunnel_dev) {
@@ -1362,6 +1627,10 @@ static int __net_init ipgre_init_net(str
err_reg_dev:
ipgre_dev_free(ign->fb_tunnel_dev);
err_alloc_dev:
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ ipgre_tap_bridge_fini();
+err_out:
+#endif
return err;
}

@@ -1375,6 +1644,9 @@ static void __net_exit ipgre_exit_net(st
ipgre_destroy_tunnels(ign, &list);
unregister_netdevice_many(&list);
rtnl_unlock();
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ ipgre_tap_bridge_fini();
+#endif
}

static struct pernet_operations ipgre_net_ops = {

--
Stefan Gula
CCNP, CCIP
--
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Eric Dumazet

unread,
Jan 16, 2012, 8:30:01 AM1/16/12
to
Le lundi 16 janvier 2012 à 13:13 +0100, Štefan Gula a écrit :
> From: Stefan Gula <ste...@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 informations in
> it. It simulates the Bridge bahaviour learing 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
> enacapsulated 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 <ste...@gmail.com>
>
> ---
>
> Patch was tested for more than one year in real network infrastructure
> consisting of 98 Linux based access-points
>

OK, but please always send new patches on top on net-next tree.

> diff -uprN -X linux-3.2.1-orig/Documentation/dontdiff
> linux-3.2.1-orig/Documentation/dontdiff
> linux-3.2.1-my/Documentation/dontdiff
> --- linux-3.2.1-orig/Documentation/dontdiff 2012-01-16 12:32:18.000000000 +0100
> +++ linux-3.2.1-my/Documentation/dontdiff 2012-01-12 20:42:45.000000000 +0100
> @@ -260,5 +260,3 @@ wakeup.lds
> zImage*
> zconf.hash.c
> zoffset.h
> -mkpiggy
> -mdp

Hmm, what is this ?
Not sure if you need a 'struct mac_addr' for this...

unsigned char mac_addr[ETH_ALEN] ?
You can now use kfree_rcu() and get rid of ipgre_tap_bridge_rcu_free()
Unfortunately you call ipgre_tap_bridge_get() from
ipgre_tap_bridge_get_raddr() but you dont release the refcount on
use_count. Leak in ipgre_tunnel_xmit()


> +__be32 ipgre_tap_bridge_get_raddr(struct ip_tunnel *tunnel,
> + const unsigned char *addr)
> +{
> + struct ipgre_tap_bridge_entry *entry;
> + entry = ipgre_tap_bridge_get(tunnel, addr);

So maybe you want __ipgre_tap_bridge_get(tunnel, addr); here ?
Since you are called from timer, no need to use _bh() variant.


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->ageing_timer + 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_bh(&tunnel->hash_lock);
> + mod_timer(&tunnel->gc_timer, round_jiffies(next_timer + HZ/4));

wow... why setup a 250 ms timer, if entries are valid 300 seconds ?
if (!is_multicast_ether_addr(tethhdr->h_source)) ?
please format like this :

if ((dev->type == ARPHRD_ETHER) &&
ipv4_is_multicast(tunnel->parms.iph.daddr))

David Laight

unread,
Jan 16, 2012, 8:40:01 AM1/16/12
to
> > + 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->ageing_timer + 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_bh(&tunnel->hash_lock);
> > + mod_timer(&tunnel->gc_timer, round_jiffies(next_timer + HZ/4));
>
> wow... why setup a 250 ms timer, if entries are valid 300 seconds ?

Isn't that code trying to wakeup 250ms after the first expiry of any
of its items?

Do you even need a timer at all?

It may be enough to just put a timestamp into each entry
and tidy up when scanning one of the hash chains in (say)
the 'add item' path - when you need write access anyway.

A hash table might not be the best structure either!
The hash lookup is still o(n) for n >> table_size.
It also may be likely that you'll do repeated lookups for a small
number of items - in which case using a hash to cache recent lookups
might be useful (maybe with some type of balanced tree structure)

David

David Lamparter

unread,
Jan 16, 2012, 8:40:02 AM1/16/12
to
On Mon, Jan 16, 2012 at 01:13:19PM +0100, Štefan Gula wrote:
> it learns IP address of peer which encapsulated given packet.

This feature is already present in the Linux kernel, albeit only for IP
to IP lookup. Please look at "userspace ARPd" and its relation to
multipoint GRE. OpenNHRP is the associated userspace part.

That code reuses the existing neighbor management infrastructure. Adding
support for gretap and automatic learning from incoming packets
shouldn't be too hard...


-David

Štefan Gula

unread,
Jan 16, 2012, 8:50:01 AM1/16/12
to
2012/1/16 David Laight <David....@aculab.com>:
That part of code is modified from original linux bridge code, as I
wanted to avoid of developing something that was already developed.
The timer is actually needed to network


--
Stefan Gula

Štefan Gula

unread,
Jan 16, 2012, 9:10:01 AM1/16/12
to
Dňa 16. januára 2012 14:19, Eric Dumazet <eric.d...@gmail.com> napísal/a:
Sorry, this one is not related to my patch, I have follwed the
guideline and those 2 files always end-up in my diff file even I
didn't modify them, so I have added them into dontdiff file assuming
that that file will not pop-up in my diff file. Apparently wrong
assumption, so please ignore those lines
not sure either, but I used in that time when I developed the code. Do
I have to change that to make this patch to kernel?
hmm... for that part of code was copy & pasted from linux bridge code
from version 2.6.26. Do I have to change that or is it optional?
Hmmm.. I am sorry, I am maybe not that expert on C coding, as most of
the codes were copied from linux bridge code. Can you give me a hint
how should I change that?
again copied structure from linux bridge code
>
>
>        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->ageing_timer + 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_bh(&tunnel->hash_lock);
>> +     mod_timer(&tunnel->gc_timer, round_jiffies(next_timer + HZ/4));
>
> wow... why setup a 250 ms timer, if entries are valid 300 seconds ?
no idea, it was in original linux bridge code
fixed
fixed
Stefan Gula
CCNP, CCIP

Eric Dumazet

unread,
Jan 16, 2012, 9:30:02 AM1/16/12
to
Le lundi 16 janvier 2012 à 15:05 +0100, Štefan Gula a écrit :
> Dňa 16. januára 2012 14:19, Eric Dumazet <eric.d...@gmail.com> napísal/a:

> > Unfortunately you call ipgre_tap_bridge_get() from
> > ipgre_tap_bridge_get_raddr() but you dont release the refcount on
> > use_count. Leak in ipgre_tunnel_xmit()
> >
> >
> >> +__be32 ipgre_tap_bridge_get_raddr(struct ip_tunnel *tunnel,
> >> + const unsigned char *addr)
> >> +{
> >> + struct ipgre_tap_bridge_entry *entry;
> >> + entry = ipgre_tap_bridge_get(tunnel, addr);
> >
> > So maybe you want __ipgre_tap_bridge_get(tunnel, addr); here ?
> >
> Hmmm.. I am sorry, I am maybe not that expert on C coding, as most of
> the codes were copied from linux bridge code. Can you give me a hint
> how should I change that?

I dont see in net/bridge the code you copied.

Could you give more information ?

Štefan Gula

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Jan 16, 2012, 9:50:02 AM1/16/12
to
Dňa 16. januára 2012 15:25, Eric Dumazet <eric.d...@gmail.com> napísal/a:
> Le lundi 16 janvier 2012 à 15:05 +0100, Štefan Gula a écrit :
>> Dňa 16. januára 2012 14:19, Eric Dumazet <eric.d...@gmail.com> napísal/a:
>
>> > Unfortunately you call ipgre_tap_bridge_get() from
>> > ipgre_tap_bridge_get_raddr() but you dont release the refcount on
>> > use_count. Leak in ipgre_tunnel_xmit()
>> >
>> >
>> >> +__be32 ipgre_tap_bridge_get_raddr(struct ip_tunnel *tunnel,
>> >> +     const unsigned char *addr)
>> >> +{
>> >> +     struct ipgre_tap_bridge_entry *entry;
>> >> +     entry = ipgre_tap_bridge_get(tunnel, addr);
>> >
>> >        So maybe you want __ipgre_tap_bridge_get(tunnel, addr); here ?
>> >
>> Hmmm.. I am sorry, I am maybe not that expert on C coding, as most of
>> the codes were copied from linux bridge code. Can you give me a hint
>> how should I change that?
>
> I dont see in net/bridge the code you copied.
>
> Could you give more information ?
>
>

File: net/birdge/br_fdb.c
Functions:
__br_fdb_get
br_fdb_get
My analogy fuctions:
__ipgre_tap_bridge_get
ipgre_tap_bridge_get

--
Stefan Gula

Eric Dumazet

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Jan 16, 2012, 10:20:01 AM1/16/12
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Le lundi 16 janvier 2012 à 15:47 +0100, Štefan Gula a écrit :

> File: net/birdge/br_fdb.c
> Functions:
> __br_fdb_get
> br_fdb_get
> My analogy fuctions:
> __ipgre_tap_bridge_get
> ipgre_tap_bridge_get
>

There is no br_fdb_get(), you copied some buggy code I am afraid.

Read again your patch.

If you use atomic_inc_not_zero(&x->use_count), then you must do the
atomic_dec() or leak entries.

Current bridge code doesnt use atomic_inc_not_zero()

Štefan Gula

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Jan 16, 2012, 10:30:02 AM1/16/12
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Dňa 16. januára 2012 16:13, Eric Dumazet <eric.d...@gmail.com> napísal/a:
> Le lundi 16 janvier 2012 à 15:47 +0100, Štefan Gula a écrit :
>
>> File: net/birdge/br_fdb.c
>> Functions:
>> __br_fdb_get
>> br_fdb_get
>> My analogy fuctions:
>> __ipgre_tap_bridge_get
>> ipgre_tap_bridge_get
>>
>
> There is no br_fdb_get(), you copied some buggy code I am afraid.
>
> Read again your patch.
>
> If you use atomic_inc_not_zero(&x->use_count), then you must do the
> atomic_dec() or leak entries.
>
> Current bridge code doesnt use atomic_inc_not_zero()
>
>
>
You are right, new bridge code doesn't have such function, I will adjust that

Stephen Hemminger

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Jan 16, 2012, 11:40:02 AM1/16/12
to
On Mon, 16 Jan 2012 13:13:19 +0100
Štefan Gula <ste...@gmail.com> wrote:

> From: Stefan Gula <ste...@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 informations in
> it. It simulates the Bridge bahaviour learing 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
> enacapsulated 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 <ste...@gmail.com>

Thanks for the effort, but it is duplicating existing functionality.
It possible to do this already with existing gretap device and the
current bridge.

The same thing is also supported by OpenVswitch.

Štefan Gula

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Jan 16, 2012, 12:30:03 PM1/16/12
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Dňa 16. januára 2012 17:36, Stephen Hemminger <shemm...@vyatta.com> napísal/a:
> On Mon, 16 Jan 2012 13:13:19 +0100
> Štefan Gula <ste...@gmail.com> wrote:
>
>> From: Stefan Gula <ste...@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 informations in
>> it. It simulates the Bridge bahaviour learing 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
>> enacapsulated 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 <ste...@gmail.com>
>
> Thanks for the effort, but it is duplicating existing functionality.
> It possible to do this already with existing gretap device and the
> current bridge.
>
> The same thing is also supported by OpenVswitch.
>

gretap with bridge will not do the same as gretap allows you to only
encapsulate L2 frames inside the GRE - this one part is actually
utilized in my code. GRE multipoint implementation is also utilized in
my code as well. But what is missing is forwarding logic here, which
prevents the traffic going not optimal way. Scenario one - e.g. if you
connect through 3 sites with using 1 gretap multipoint VPN, it always
forwards frames between site 1 and site 2 even if they are unicast.
That represents waste of bandwidth for site 3. Now assume that there
will be more than 40 sites and I hope you see that single current
multipoint gretap is not also good solution here

The second scenario - e.g. using 3 sites using point-to-point gretap
interfaces between each 2 sites (2 gretap VPN interfaces per site) and
bridging those interfaces with real ones results in looped topology
which needs to utilized STP inside to prevent loops. Once STP
converges the topology will looks like this, traffic from site 1 to
site 2 will go always directly by the way of unicast (on GRE level),
from site 2 to site 3 always directly by the way of unicast (on GRE
level) and from site 1 to site 3 will go indirectly through site 2 due
STP limitations, which results in another not optimalized traffic
flows. Now assume that the number of sites rises, so gretap+standard
bridge code is also not a good solution here.

My code utilizes it that way that I have extended the gretap
multipoint interface with the forwarding logic e.g. using 3 sites,
each site uses only one gretap VPN interface and if destination MAC
address is known to bridge code inside the gretap interface forwarding
logic, it forwards it towards only VPN endpoint that actually need
that by the way of unicasting on GRE level. On the other hand if the
destination MAC address is unknown or destination MAC address is L2
multicast or L2 broadcast than the frame is spread out through
multicasting on GRE level, providing delivery mechanism analogous to
standard switches on top of the multipoint GRE tunnels.

I also get through briefly over OpenVswitch documentation and found
that it is more related to virtualization inside the box like VMware
switches or so and not to such technologies interconnecting two or
more separate segments over routed L3 infrastructure - there is a
mention about the CAPWAP UDP transport but this is more related to
WiFi implementations than generic ones. My patch also doesn't need any
special userspace api to be configured. It utilizes the existing one.

Štefan Gula

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Jan 16, 2012, 1:40:01 PM1/16/12
to
2012/1/16 Stephen Hemminger <shemm...@vyatta.com>:
> On Mon, 16 Jan 2012 18:26:57 +0100
> Couldn't this be controlled from user space either by programming
> the FDB with netlink or doing alternative version of STP?
For certain small number of clients yes, for many clients it is
administrative nightmare. e.g. I have in my network more than 98 VPN
endpoints and 4k users constantly migrating from one site to another.
This solution provides me flexible way to do this, with no
administrative work.

Stephen Hemminger

unread,
Jan 16, 2012, 1:40:02 PM1/16/12
to
On Mon, 16 Jan 2012 18:26:57 +0100
Couldn't this be controlled from user space either by programming
the FDB with netlink or doing alternative version of STP?


Štefan Gula

unread,
Jan 16, 2012, 2:50:01 PM1/16/12
to
From: Stefan Gula <ste...@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 <ste...@gmail.com>

---

code was merged with latest bridge code and should be easily comparable
+++ linux-3.2.1-my/net/ipv4/ip_gre.c 2012-01-16 20:42:03.000000000 +0100
@@ -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 +139,191 @@ 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 <ste...@gmail.com>
+ */
+struct mac_addr {
+ unsigned char addr[6];
+};
+
+struct ipgre_tap_bridge_entry {
+ struct hlist_node hlist;
+ u32 raddr;
+ struct mac_addr addr;
+ struct net_device *dev;
+ struct rcu_head rcu;
+ unsigned long updated;
+};
+
+static struct kmem_cache *ipgre_tap_bridge_cache __read_mostly;
+static u32 ipgre_salt __read_mostly;
+
+int __net_init ipgre_tap_bridge_init(void)
+{
+ ipgre_tap_bridge_cache = kmem_cache_create("ipgre_tap_bridge_cache",
+ sizeof(struct ipgre_tap_bridge_entry),
+ 0,
+ SLAB_HWCACHE_ALIGN, NULL);
+ if (!ipgre_tap_bridge_cache)
+ return -ENOMEM;
+ get_random_bytes(&ipgre_salt, sizeof(ipgre_salt));
+ return 0;
+}
+
+void ipgre_tap_bridge_fini(void)
+{
+ kmem_cache_destroy(ipgre_tap_bridge_cache);
+}
+
+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 void ipgre_tap_bridge_rcu_free(struct rcu_head *head)
+{
+ struct ipgre_tap_bridge_entry *entry
+ = container_of(head, struct ipgre_tap_bridge_entry, rcu);
+ kmem_cache_free(ipgre_tap_bridge_cache, entry);
+}
+
+static inline void ipgre_tap_bridge_delete(struct
ipgre_tap_bridge_entry *entry)
+{
+ hlist_del_rcu(&entry->hlist);
+ call_rcu(&entry->rcu, ipgre_tap_bridge_rcu_free);
+}
+
+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));
+}
+
+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);
+}
+
+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, 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, 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, addr))
+ return entry;
+ }
+ return NULL;
+}
+
+static struct ipgre_tap_bridge_entry *ipgre_tap_bridge_create(
+ struct hlist_head *head,
+ u32 source,
+ const unsigned char *addr, struct net_device *dev)
+{
+ struct ipgre_tap_bridge_entry *entry;
+ entry = kmem_cache_alloc(ipgre_tap_bridge_cache, GFP_ATOMIC);
+ if (entry) {
+ memcpy(entry->addr.addr, addr, ETH_ALEN);
+ hlist_add_head_rcu(&entry->hlist, head);
+ entry->raddr = source;
+ entry->dev = dev;
+ entry->updated = jiffies;
+ }
+ return entry;
+}
+
+__be32 ipgre_tap_bridge_get_raddr(struct ip_tunnel *tunnel,
+ const unsigned char *addr)
+{
+ struct ipgre_tap_bridge_entry *entry;
+ entry = __ipgre_tap_bridge_get(tunnel, addr);
+ if (entry == NULL)
+ return 0;
+ else
+ return entry->raddr;
+}
+
+#endif
/* Tunnel hash table */

/*
@@ -563,6 +753,13 @@ static int ipgre_rcv(struct sk_buff *skb
int offset = 4;
__be16 gre_proto;

+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ u32 orig_source;
+ struct hlist_head *head;
+ struct ipgre_tap_bridge_entry *entry;
+ struct ethhdr *tethhdr;
+#endif
+
if (!pskb_may_pull(skb, 16))
goto drop_nolock;

@@ -659,10 +856,39 @@ static int ipgre_rcv(struct sk_buff *skb
tunnel->dev->stats.rx_errors++;
goto drop;
}
-
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ orig_source = iph->saddr;
+#endif
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 (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_bh(&tunnel->hash_lock);
+ if (!ipgre_tap_bridge_find(head,
+ tethhdr->h_source))
+ ipgre_tap_bridge_create(
+ head,
+ orig_source,
+ tethhdr->h_source,
+ tunnel->dev);
+ spin_unlock_bh(&tunnel->hash_lock);
+ }
+ }
+ }
+#endif
}

tstats = this_cpu_ptr(tunnel->dev->tstats);
@@ -716,7 +942,19 @@ static netdev_tx_t ipgre_tunnel_xmit(str
tiph = &tunnel->parms.iph;
}

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

if (skb_dst(skb) == NULL) {
@@ -1209,6 +1447,16 @@ 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 +1467,12 @@ 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);
@@ -1341,6 +1595,12 @@ static int __net_init ipgre_init_net(str
struct ipgre_net *ign = net_generic(net, ipgre_net_id);
int err;

+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ err = ipgre_tap_bridge_init();
+ if (err)
+ goto err_out;
+#endif
+
ign->fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "gre0",
ipgre_tunnel_setup);
if (!ign->fb_tunnel_dev) {
@@ -1362,6 +1622,10 @@ static int __net_init ipgre_init_net(str
err_reg_dev:
ipgre_dev_free(ign->fb_tunnel_dev);
err_alloc_dev:
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ ipgre_tap_bridge_fini();
+err_out:
+#endif
return err;
}

@@ -1375,6 +1639,9 @@ static void __net_exit ipgre_exit_net(st
ipgre_destroy_tunnels(ign, &list);
unregister_netdevice_many(&list);
rtnl_unlock();
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ ipgre_tap_bridge_fini();
+#endif
}

static struct pernet_operations ipgre_net_ops = {

David Lamparter

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Jan 16, 2012, 3:30:01 PM1/16/12
to
At the risk of repeating myself, Linux GRE support already has
provisions for multipoint tunnels. And unlike your code, those reuse the
existing neighbor table infrastructure, including all of its user
interface and introspection capabilities.

It's actually slightly visible in your patch:

On Mon, Jan 16, 2012 at 08:45:14PM +0100, Štefan Gula wrote:
> +++ linux-3.2.1-my/net/ipv4/ip_gre.c 2012-01-16 20:42:03.000000000 +0100
> @@ -716,7 +942,19 @@ static netdev_tx_t ipgre_tunnel_xmit(str
[...]
> /* NBMA tunnel */
>
> if (skb_dst(skb) == NULL) {


-David

Eric Dumazet

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Jan 16, 2012, 3:30:02 PM1/16/12
to
Le lundi 16 janvier 2012 à 20:45 +0100, Štefan Gula a écrit :
> From: Stefan Gula <ste...@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 <ste...@gmail.com>
>
> ---
>
> code was merged with latest bridge code and should be easily comparable
>

Please make sure it applies properly on net-next tree.

That is mandatory.
Did I mention : ETH_ALEN ?

> +};
> +
> +struct ipgre_tap_bridge_entry {
> + struct hlist_node hlist;
> + u32 raddr;

__be32 raddr ?
Did I mention : kfree_rcu() ?
__be32 source,

> + const unsigned char *addr, struct net_device *dev)
> +{
> + struct ipgre_tap_bridge_entry *entry;
> + entry = kmem_cache_alloc(ipgre_tap_bridge_cache, GFP_ATOMIC);
> + if (entry) {
> + memcpy(entry->addr.addr, addr, ETH_ALEN);
> + hlist_add_head_rcu(&entry->hlist, head);

Thats bogus.

You must init all entry fields _before_ inserting entry in hash table.
Please run sparse on your code... (make C=2 ...)

orig_source is not u32, but __be32
You dont need the _bh() variant here, since we run from softirq handler.

> + if (!ipgre_tap_bridge_find(head,
> + tethhdr->h_source))
> + ipgre_tap_bridge_create(
> + head,
> + orig_source,
> + tethhdr->h_source,
> + tunnel->dev);
> + spin_unlock_bh(&tunnel->hash_lock);
> + }
> + }
> + }
> +#endif
> }
>
> tstats = this_cpu_ptr(tunnel->dev->tstats);
> @@ -716,7 +942,19 @@ static netdev_tx_t ipgre_tunnel_xmit(str
> tiph = &tunnel->parms.iph;
> }
>
> +#ifdef CONFIG_NET_IPGRE_BRIDGE
> + rcu_read_lock();
> + if ((dev->type == ARPHRD_ETHER) &&
> + ipv4_is_multicast(tunnel->parms.iph.daddr))
> + dst = ipgre_tap_bridge_get_raddr(tunnel,
> + ((struct ethhdr *)skb->data)->h_dest);
> + rcu_read_unlock();

this rcu_read_lock()/rcu_read_unlock() pair should be done in
ipgre_tap_bridge_get_raddr() instead... so we dont hit this for all
packets.

> + if (dst == 0)
> + dst = tiph->daddr;
> + if (dst == 0) {
> +#else
> if ((dst = tiph->daddr) == 0) {
> +#endif
> /* NBMA tunnel */
>

General comment :

It would be nice this stuff is installed on a new "ip tunnel add"
option...

Hash table is 2048 bytes long... and an "ip tunnel " option would permit
to size the hash table eventually, instead of fixed 256 slots.

Jesse Gross

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Jan 16, 2012, 4:30:03 PM1/16/12
to
2012/1/16 Štefan Gula <ste...@gmail.com>:
I understand what you're trying to do and I think that the goal makes
sense but I agree with Stephen that this is not the right way to go
about it. I see two issues:

* It copies a lot of bridge code, making it unmaintainable and
inflexible to other use cases.
* The implementation exists in the GRE protocol stack but it applies
equally to other tunneling protocols as well (VXLAN comes to mind).

Open vSwitch doesn't quite do this level of learning yet but it's the
direction that we want to move in (and there's nothing particularly
virtualization specific about it). What I think makes the most sense
is to create some internal interfaces to the GRE stack that exposes
the information needed to do learning. That way there is only one
instance of the protocol code for each tunneling mechanism and then
each way of managing those addresses (i.e. the current device-based
mechanism, Open vSwitch, potentially a direct bridge-based mechanism,
etc.) can be reused as well.

Štefan Gula

unread,
Jan 16, 2012, 6:00:02 PM1/16/12
to
Dňa 16. januára 2012 21:29, David Lamparter <equ...@diac24.net> napísal/a:
> At the risk of repeating myself, Linux GRE support already has
> provisions for multipoint tunnels. And unlike your code, those reuse the
> existing neighbor table infrastructure, including all of its user
> interface and introspection capabilities.
>
> It's actually slightly visible in your patch:
>
> On Mon, Jan 16, 2012 at 08:45:14PM +0100, Štefan Gula wrote:
>> +++ linux-3.2.1-my/net/ipv4/ip_gre.c  2012-01-16 20:42:03.000000000 +0100
>> @@ -716,7 +942,19 @@ static netdev_tx_t ipgre_tunnel_xmit(str
> [...]
>>               /* NBMA tunnel */
>>
>>               if (skb_dst(skb) == NULL) {
>
>
> -David

That code you are referring to is used only for routed traffic inside
GRE - L3 traffic over L3 routed infrastructure. My patch is dealing
with L2 traffic over L3 routed infrastructure - so the decision here
is based on destination MAC addresses and not based on IPv4/IPv6
addresses.

--
Stefan Gula
CCNP, CCIP

Štefan Gula

unread,
Jan 16, 2012, 6:20:02 PM1/16/12
to
Dňa 16. januára 2012 21:28, Eric Dumazet <eric.d...@gmail.com> napísal/a:
I agree with you, but for the start of this feature I believe static
slots size is enough here - same limitation is inside the original
linux bridge code. I have merged hopefully all your comments and here
is the newest patch:
+++ linux-3.2.1-my/net/ipv4/ip_gre.c 2012-01-17 00:01:17.000000000 +0100
@@ -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 +139,184 @@ 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 <ste...@gmail.com>
+ */
+struct ipgre_tap_bridge_entry {
+ struct hlist_node hlist;
+ __be32 raddr;
+ unsigned char addr[ETH_ALEN];
+ struct net_device *dev;
+ struct rcu_head rcu;
+ unsigned long updated;
+};
+
+static struct kmem_cache *ipgre_tap_bridge_cache __read_mostly;
+static u32 ipgre_salt __read_mostly;
+
+static int __net_init ipgre_tap_bridge_init(void)
+{
+ ipgre_tap_bridge_cache = kmem_cache_create("ipgre_tap_bridge_cache",
+ sizeof(struct ipgre_tap_bridge_entry),
+ 0,
+ SLAB_HWCACHE_ALIGN, NULL);
+ if (!ipgre_tap_bridge_cache)
+ return -ENOMEM;
+ get_random_bytes(&ipgre_salt, sizeof(ipgre_salt));
+ return 0;
+}
+
+static void ipgre_tap_bridge_fini(void)
+{
+ kmem_cache_destroy(ipgre_tap_bridge_cache);
+}
+
+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,
+ u32 source,
+ const unsigned char *addr, struct net_device *dev)
+{
+ struct ipgre_tap_bridge_entry *entry;
+ entry = kmem_cache_alloc(ipgre_tap_bridge_cache, GFP_ATOMIC);
+ if (entry) {
+ memcpy(entry->addr, addr, ETH_ALEN);
+ entry->raddr = source;
+ entry->dev = dev;
+ 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;
+ struct ipgre_tap_bridge_entry *entry;
+ rcu_read_lock();
+ entry = __ipgre_tap_bridge_get(tunnel, addr);
+ if (entry == NULL)
+ raddr = 0;
+ else
+ raddr = entry->raddr;
+ rcu_read_unlock();
+ return raddr;
+}
+
+#endif
/* Tunnel hash table */

/*
@@ -563,6 +746,13 @@ static int ipgre_rcv(struct sk_buff *skb
int offset = 4;
__be16 gre_proto;

+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ __be32 orig_source;
+ struct hlist_head *head;
+ struct ipgre_tap_bridge_entry *entry;
+ struct ethhdr *tethhdr;
+#endif
+
if (!pskb_may_pull(skb, 16))
goto drop_nolock;

@@ -659,10 +849,39 @@ static int ipgre_rcv(struct sk_buff *skb
tunnel->dev->stats.rx_errors++;
goto drop;
}
-
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ orig_source = iph->saddr;
+#endif
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 (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,
+ tunnel->dev);
+ spin_unlock(&tunnel->hash_lock);
+ }
+ }
+ }
+#endif
}

tstats = this_cpu_ptr(tunnel->dev->tstats);
@@ -716,7 +935,17 @@ static netdev_tx_t ipgre_tunnel_xmit(str
tiph = &tunnel->parms.iph;
}

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

if (skb_dst(skb) == NULL) {
@@ -1209,6 +1438,16 @@ 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 +1458,12 @@ 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);
@@ -1341,6 +1586,12 @@ static int __net_init ipgre_init_net(str
struct ipgre_net *ign = net_generic(net, ipgre_net_id);
int err;

+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ err = ipgre_tap_bridge_init();
+ if (err)
+ goto err_out;
+#endif
+
ign->fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "gre0",
ipgre_tunnel_setup);
if (!ign->fb_tunnel_dev) {
@@ -1362,6 +1613,10 @@ static int __net_init ipgre_init_net(str
err_reg_dev:
ipgre_dev_free(ign->fb_tunnel_dev);
err_alloc_dev:
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ ipgre_tap_bridge_fini();
+err_out:
+#endif
return err;
}

@@ -1375,6 +1630,9 @@ static void __net_exit ipgre_exit_net(st
ipgre_destroy_tunnels(ign, &list);
unregister_netdevice_many(&list);
rtnl_unlock();
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ ipgre_tap_bridge_fini();
+#endif
}

static struct pernet_operations ipgre_net_ops = {

Štefan Gula

unread,
Jan 16, 2012, 6:50:02 PM1/16/12
to
Dňa 16. januára 2012 22:22, Jesse Gross <je...@nicira.com> napísal/a:
I agree with you that using such approach of copying bridge code with
some modifications is maybe not flexible enough, but on the other hand
it does the job needed. It also doesn't breaks any previous
compatibility of usage of gretap interfaces as it modifies the
encapsulation and decapsulation part of codes *how the traffic goes to
and from remote destinations), which doesn't face any change on the
internal linkages coding inside the box (e.g. linking that gretap
interface to standard logical bridge interface is still fully
possible). I would rather see getting some standard set of generic
bridge code, which can be reused anywhere in network stack, but for
now this is the only way I know how to do it. Exposing the GRE
interfaces will not do the job as what I needed was to rebuild the
bridge logic to allow learning endpoint IPs instead of network ports
IDs (it's almost the same as using multiple gretap interfaces inside
one bridge.interface) To obtain back the maintainability I would
assume redesigning the bridge code is the best way here, but I am not
that well coder to do it myself. So if anybody is interested in this
feel free to do it.

Eric Dumazet

unread,
Jan 16, 2012, 11:50:02 PM1/16/12
to
Le mardi 17 janvier 2012 à 00:11 +0100, Štefan Gula a écrit :

> I agree with you, but for the start of this feature I believe static
> slots size is enough here - same limitation is inside the original
> linux bridge code. I have merged hopefully all your comments and here
> is the newest patch:



1) Before sending a new version of your patch, please fix your mailer,
you can read Documentation/email-clients.txt for hints.

Send it to you and check you can apply it.
Then, once you are confident its OK, you can send it to netdev.

Right now, it doesnt apply, because of unexpected line wraps.

# cd next-next
# cat /tmp/patch | patch -p1
patching file include/net/ipip.h
patching file net/ipv4/Kconfig
patching file net/ipv4/ip_gre.c
patch: **** malformed patch at line 495: ipgre_tap_bridge_entry *entry)


2) You call ipgre_tap_bridge_fini() from ipgre_exit_net() and
ipgre_init_net(), thats completely bogus if CONFIG_NET_NS=y

Just remove the struct kmem_cache *ipgre_tap_bridge_cache
and use instead kmalloc(sizeof(...))/kfree(ptr) instead.

3) ipgre_tap_bridge_init() should not be __net_init, but __init


4) I cant find why you store 'struct net_device *dev;' in a
ipgre_tap_bridge_entry, it seems you never read it ?

5) Also please add an empty line between variable declaration and
function body. Also, we prefer an alignement of parameters.

For example :

static __be32 ipgre_tap_bridge_get_raddr(struct ip_tunnel *tunnel,
const unsigned char *addr)
{
__be32 raddr;
struct ipgre_tap_bridge_entry *entry;
rcu_read_lock();
entry = __ipgre_tap_bridge_get(tunnel, addr);
if (entry == NULL)
raddr = 0;
else
raddr = entry->raddr;
rcu_read_unlock();
return raddr;
}

should be :

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;

Štefan Gula

unread,
Jan 17, 2012, 3:10:02 AM1/17/12
to
Dňa 17. januára 2012 5:47, Eric Dumazet <eric.d...@gmail.com> napísal/a:
> Le mardi 17 janvier 2012 à 00:11 +0100, Štefan Gula a écrit :
>
>> I agree with you, but for the start of this feature I believe static
>> slots size is enough here - same limitation is inside the original
>> linux bridge code. I have merged hopefully all your comments and here
>> is the newest patch:
>
>
>
> 1) Before sending a new version of your patch, please fix your mailer,
> you can read Documentation/email-clients.txt for hints.
>
Sorry, I have to test it as I am using clasical gmail web GUI to send emails

> Send it to you and check you can apply it.
> Then, once you are confident its OK, you can send it to netdev.
>
> Right now, it doesnt apply, because of unexpected line wraps.
>
> # cd next-next
> # cat /tmp/patch | patch -p1
> patching file include/net/ipip.h
> patching file net/ipv4/Kconfig
> patching file net/ipv4/ip_gre.c
> patch: **** malformed patch at line 495: ipgre_tap_bridge_entry *entry)
>
>
> 2) You call ipgre_tap_bridge_fini() from ipgre_exit_net() and
> ipgre_init_net(), thats completely bogus if CONFIG_NET_NS=y
>
> Just remove the struct kmem_cache *ipgre_tap_bridge_cache
> and use instead kmalloc(sizeof(...))/kfree(ptr) instead.
>
As this is completely the same part of code from net/bridge/br_fdb.c,
can you give me a hint about how change that as I believe it should be
changed also there?

> 3) ipgre_tap_bridge_init() should not be __net_init, but __init
>
Ok

>
> 4) I cant find why you store 'struct net_device *dev;' in a
> ipgre_tap_bridge_entry, it seems you never read it ?
>
yes you are right, it is not needed - removed from code

> 5) Also please add an empty line between variable declaration and
> function body. Also, we prefer an alignement of parameters.
>
I used scripts/checkpatch.pl to check my coding styles, but apparently
this is missing from it as it never complains before about this.
Anyway hopefully done ok based your comments

Eric Dumazet

unread,
Jan 17, 2012, 3:30:02 AM1/17/12
to
Le mardi 17 janvier 2012 à 09:04 +0100, Štefan Gula a écrit :
> Dňa 17. januára 2012 5:47, Eric Dumazet <eric.d...@gmail.com> napísal/a:
> >
> > 2) You call ipgre_tap_bridge_fini() from ipgre_exit_net() and
> > ipgre_init_net(), thats completely bogus if CONFIG_NET_NS=y
> >
> > Just remove the struct kmem_cache *ipgre_tap_bridge_cache
> > and use instead kmalloc(sizeof(...))/kfree(ptr) instead.
> >
> As this is completely the same part of code from net/bridge/br_fdb.c,
> can you give me a hint about how change that as I believe it should be
> changed also there?

Please dont copy code you dont understand :(

bridge code is ok, but not yours, since you destroy the kmem_cache when
a net namespace exits.

Either you fix your code, either you change your memory allocations to
mere kmalloc()/kfree() calls and dont care of a private kmem_cache you
have to create and destroy.

Since you ask a SLAB_HWCACHE_ALIGN, the SLUB allocator will anyway merge
your kmem_cache with the standard one (kmalloc-64 I guess)

Štefan Gula

unread,
Jan 17, 2012, 5:00:02 AM1/17/12
to
Dňa 17. januára 2012 10:50, David Lamparter <equ...@diac24.net> napísal/a:
> On Mon, Jan 16, 2012 at 11:52:25PM +0100, Štefan Gula wrote:
>> Dňa 16. januára 2012 21:29, David Lamparter <equ...@diac24.net> napísal/a:
>> > At the risk of repeating myself, Linux GRE support already has
>> > provisions for multipoint tunnels. And unlike your code, those reuse the
>> > existing neighbor table infrastructure, including all of its user
>> > interface and introspection capabilities.
>> >
>> > It's actually slightly visible in your patch:
>> >
>> > On Mon, Jan 16, 2012 at 08:45:14PM +0100, Štefan Gula wrote:
>> >> +++ linux-3.2.1-my/net/ipv4/ip_gre.c  2012-01-16 20:42:03.000000000 +0100
>> >> @@ -716,7 +942,19 @@ static netdev_tx_t ipgre_tunnel_xmit(str
>> > [...]
>> >>               /* NBMA tunnel */
>> >>
>> >>               if (skb_dst(skb) == NULL) {
>> >
>> >
>> > -David
>>
>> That code you are referring to is used only for routed traffic inside
>> GRE - L3 traffic over L3 routed infrastructure. My patch is dealing
>> with L2 traffic over L3 routed infrastructure - so the decision here
>> is based on destination MAC addresses and not based on IPv4/IPv6
>> addresses.
>
> Yes, it currently only does IPv4/IPv6 -> IPv4 through the neighbor
> table. That doesn't mean it can't be extended to handle ethernet
> addresses the same way.
>
>
> -David

Routing mechanisms and switching mechanisms works completely
different, in switching you simply don't have anything like next-hop
from routing, which can be resolved by utilizing modified ARP message
and there is also absolutely no hierarchy in MAC address (like you
have in routing table), so I seriously doubt that it can be done the
same way, but I am opened to ideas here. So how would you do like to
do that?

David Lamparter

unread,
Jan 17, 2012, 5:00:02 AM1/17/12
to
On Mon, Jan 16, 2012 at 11:52:25PM +0100, Štefan Gula wrote:
> Dňa 16. januára 2012 21:29, David Lamparter <equ...@diac24.net> napísal/a:
> > At the risk of repeating myself, Linux GRE support already has
> > provisions for multipoint tunnels. And unlike your code, those reuse the
> > existing neighbor table infrastructure, including all of its user
> > interface and introspection capabilities.
> >
> > It's actually slightly visible in your patch:
> >
> > On Mon, Jan 16, 2012 at 08:45:14PM +0100, Štefan Gula wrote:
> >> +++ linux-3.2.1-my/net/ipv4/ip_gre.c  2012-01-16 20:42:03.000000000 +0100
> >> @@ -716,7 +942,19 @@ static netdev_tx_t ipgre_tunnel_xmit(str
> > [...]
> >>               /* NBMA tunnel */
> >>
> >>               if (skb_dst(skb) == NULL) {
> >
> >
> > -David
>
> That code you are referring to is used only for routed traffic inside
> GRE - L3 traffic over L3 routed infrastructure. My patch is dealing
> with L2 traffic over L3 routed infrastructure - so the decision here
> is based on destination MAC addresses and not based on IPv4/IPv6
> addresses.

Yes, it currently only does IPv4/IPv6 -> IPv4 through the neighbor
table. That doesn't mean it can't be extended to handle ethernet
addresses the same way.


-David

David Lamparter

unread,
Jan 17, 2012, 5:20:02 AM1/17/12
to
On Tue, Jan 17, 2012 at 10:56:51AM +0100, Štefan Gula wrote:
> Dňa 17. januára 2012 10:50, David Lamparter <equ...@diac24.net> napísal/a:
> > On Mon, Jan 16, 2012 at 11:52:25PM +0100, Štefan Gula wrote:
> >> Dňa 16. januára 2012 21:29, David Lamparter <equ...@diac24.net> napísal/a:
> >> > At the risk of repeating myself, Linux GRE support already has
> >> > provisions for multipoint tunnels. And unlike your code, those reuse the
> >> > existing neighbor table infrastructure, including all of its user
> >> > interface and introspection capabilities.
> >> >
> >> > It's actually slightly visible in your patch:
> >> >
> >> > On Mon, Jan 16, 2012 at 08:45:14PM +0100, Štefan Gula wrote:
> >> >> +++ linux-3.2.1-my/net/ipv4/ip_gre.c  2012-01-16 20:42:03.000000000 +0100
> >> >> @@ -716,7 +942,19 @@ static netdev_tx_t ipgre_tunnel_xmit(str
> >> > [...]
> >> >>               /* NBMA tunnel */
> >> >>
> >> >>               if (skb_dst(skb) == NULL) {
> >> >
> >> >
> >> > -David
> >>
> >> That code you are referring to is used only for routed traffic inside
> >> GRE - L3 traffic over L3 routed infrastructure. My patch is dealing
> >> with L2 traffic over L3 routed infrastructure - so the decision here
> >> is based on destination MAC addresses and not based on IPv4/IPv6
> >> addresses.
> >
> > Yes, it currently only does IPv4/IPv6 -> IPv4 through the neighbor
> > table. That doesn't mean it can't be extended to handle ethernet
> > addresses the same way.
>
> Routing mechanisms and switching mechanisms works completely
> different, in switching you simply don't have anything like next-hop
> from routing, which can be resolved by utilizing modified ARP message
> and there is also absolutely no hierarchy in MAC address (like you
> have in routing table), so I seriously doubt that it can be done the
> same way, but I am opened to ideas here. So how would you do like to
> do that?

NBMA GRE does not use routing mechanisms, it uses the neighbor table.
The neighbor table does not use any hierarchy in its lookups.

So you have the existing neighbor table use cases:
- IPv4 -> MAC with in-kernel ARP
- IPv6 -> MAC with in-kernel ND
- IPv4 -> IPv4 on NBMA GRE devices (without in-kernel filling)
- IPv6 -> IPv4 on NBMA GRE devices (without in-kernel filling)
You could add to that:
- MAC -> IPv4 on NBMA GRETAP devices


-David

Štefan Gula

unread,
Jan 17, 2012, 5:50:01 AM1/17/12
to
Dňa 17. januára 2012 9:29, Eric Dumazet <eric.d...@gmail.com> napísal/a:
> Le mardi 17 janvier 2012 à 09:04 +0100, Štefan Gula a écrit :
>> Dňa 17. januára 2012 5:47, Eric Dumazet <eric.d...@gmail.com> napísal/a:
>> >
>> > 2) You call ipgre_tap_bridge_fini() from ipgre_exit_net() and
>> > ipgre_init_net(), thats completely bogus if CONFIG_NET_NS=y
>> >
>> > Just remove the struct kmem_cache *ipgre_tap_bridge_cache
>> > and use instead kmalloc(sizeof(...))/kfree(ptr) instead.
>> >
>> As this is completely the same part of code from net/bridge/br_fdb.c,
>> can you give me a hint about how change that as I believe it should be
>> changed also there?
>
> Please dont copy code you dont understand :(
>
> bridge code is ok, but not yours, since you destroy the kmem_cache when
> a net namespace exits.
>
> Either you fix your code, either you change your memory allocations to
> mere kmalloc()/kfree() calls and dont care of a private kmem_cache you
> have to create and destroy.
>
> Since you ask a SLAB_HWCACHE_ALIGN, the SLUB allocator will anyway merge
> your kmem_cache with the standard one (kmalloc-64 I guess)
>
>
>
ok maybe I am getting it wrong, but I am little bit stuck here. I
recheck the original bridge code. The difference I recognize is that
in bridge code function:
br_fdb_init() and br_fdb_fini()
are called from module init and module exit functions:
br_init and br_deinit

in my code they are called from functions:
ipgre_init_net and ipgre_exit_net
instead of:
ipgre_init and ipgre_fini

To be honest I am not so familiar enough with kernel structure that I
see the difference on the first time. But I think that with your help
it can be done easily. The main idea was to create hash-table that is
used to determine the destination IPv4 address (part of the entry
structure). That hash-table should be different per each gretap
interface - I think that's the reason why I put those init and fini
inside ipgre_init_net and ipgre_exit_net. Am I right that the
placement of this calls is correct or not? If not where those calls
should be placed?

On the other hand I have no idea how to substitute those two function
with a code that you are suggesting kmalloc()/kfree(). I would be glad
if you can help me here by providing me example how to substitute
those two functions with kmalloc/kfree for the future usage (I am more
reverse engineer learner type of person than manuals reading one)

Štefan Gula

unread,
Jan 17, 2012, 5:50:01 AM1/17/12
to
Dňa 17. januára 2012 11:11, David Lamparter <equ...@diac24.net> napísal/a:
Current status:
- no general neighbor table exists (currently used build-in tables
for forwarding mechanism ARP, ND, RT, RT6 or combinations to get the
right information)

Your proposal:
- creating another kernel build-in table - MAC -> IPv4 on NBMA
GRETAP device table doesn't currently exists at all in kernel
- adjust/implement learning mechanism to populate the table
- adjust/implement forwarding mechanisms to forward frames based on
information from given table

My patch:
- creates table for holding MAC -> IPv4 on NBMA GRETAP device
- adjust/implement learning mechanism (using bridge code logic)
- adjust/implement forwarding mechanism (using bridge code logic)

So I think we are talking about the same thing here, only you are
talking in more general way, I am talking more about the actual
implementation.

Eric Dumazet

unread,
Jan 17, 2012, 5:50:01 AM1/17/12
to
Something like the following ?


Note : I also put the "orig_source = iph->saddr;"
_after_ "iph = ip_hdr(skb);"

iph = ip_hdr(skb);
#ifdef CONFIG_NET_IPGRE_BRIDGE
orig_source = iph->saddr;
#endif



diff --git a/include/net/ipip.h b/include/net/ipip.h
index a32654d..6a06fc2 100644
--- a/include/net/ipip.h
+++ b/include/net/ipip.h
@@ -27,6 +27,14 @@ 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;
+#endif

struct ip_tunnel_parm parms;

diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
index 1a8f93b..5b320a3 100644
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -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 --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 2b53a1f..df22565 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -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 +139,172 @@ 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 <ste...@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));
+
+ 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) {
+ 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;
+}
+
+#endif
/* Tunnel hash table */

/*
@@ -562,6 +733,12 @@ 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;
+ struct hlist_head *head;
+ struct ipgre_tap_bridge_entry *entry;
+ const struct ethhdr *tethhdr;
+#endif

if (!pskb_may_pull(skb, 16))
goto drop_nolock;
@@ -659,10 +836,38 @@ static int ipgre_rcv(struct sk_buff *skb)
tunnel->dev->stats.rx_errors++;
goto drop;
}
-
iph = ip_hdr(skb);
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ orig_source = iph->saddr;
+#endif
skb->protocol = eth_type_trans(skb, tunnel->dev);
skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ 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
}

tstats = this_cpu_ptr(tunnel->dev->tstats);
@@ -702,7 +907,7 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
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 +921,15 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
tiph = &tunnel->parms.iph;
}

- if ((dst = tiph->daddr) == 0) {
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+ if ((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) {
@@ -1211,6 +1424,16 @@ static int ipgre_open(struct net_device *dev)
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;
}
@@ -1221,6 +1444,12 @@ static int ipgre_close(struct net_device *dev)

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);
@@ -1707,6 +1936,9 @@ 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;

Eric Dumazet

unread,
Jan 17, 2012, 6:20:01 AM1/17/12
to
Le mardi 17 janvier 2012 à 12:00 +0100, Štefan Gula a écrit :

> >
> looks good... I am just wondering whether my previous question about
> the placement of calls for ipgre_tap_bridge_init and
> ipgre_tap_bridge_fini? Would it be also possible to have this
> done/fixed when I migrate those inside the ipgre_init and ipgre_fini ?
> I would like to have much rather identical parts of code with standard
> bridge code just in case somebody would start doing generalization of
> bridge code which can be then reused anywhere inside the kernel space
> - simpler migration process later.

Could you please stop claiming this is the same than bridge ?

There is _one_ exit function per module (ipgre_fini in ip_gre)

You wanted to destroy your kmem_cache only from this __exit function,
not from the pernet exit function (ipgre_exit_net)

Štefan Gula

unread,
Jan 17, 2012, 7:50:02 AM1/17/12
to
Dňa 17. januára 2012 12:15, Eric Dumazet <eric.d...@gmail.com> napísal/a:
> Le mardi 17 janvier 2012 à 12:00 +0100, Štefan Gula a écrit :
>
>> >
>> looks good... I am just wondering whether my previous question about
>> the placement of calls for ipgre_tap_bridge_init and
>> ipgre_tap_bridge_fini? Would it be also possible to have this
>> done/fixed when I migrate those inside the ipgre_init and ipgre_fini ?
>> I would like to have much rather identical parts of code with standard
>> bridge code just in case somebody would start doing generalization of
>> bridge code which can be then reused anywhere inside the kernel space
>> - simpler migration process later.
>
> Could you please stop claiming this is the same than bridge ?
>
> There is _one_ exit function per module (ipgre_fini in ip_gre)
>
> You wanted to destroy your kmem_cache only from this __exit function,
> not from the pernet exit function (ipgre_exit_net)
>
>
>
Ok, I will modify that, test that later today and if testing will be
successful, I will provide new version of this patch.

Stefan Gula

unread,
Jan 17, 2012, 5:40:03 PM1/17/12
to
From: Stefan Gula <ste...@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 <ste...@gmail.com>

---

code was merged with Eric Dumazet proposal (all except the reordering of orig_source as that needed to be previous value), tested and fixed with additional lines in ipgre_tap_netdev_ops struct

diff -uprN -X linux-3.2.1-orig/Documentation/dontdiff linux-3.2.1-orig/include/net/ipip.h linux-3.2.1-my/include/net/ipip.h
--- linux-3.2.1-orig/include/net/ipip.h        2012-01-12 20:42:45.000000000 +0100
+++ linux-3.2.1-my/include/net/ipip.h        2012-01-16 11:17:01.000000000 +0100
@@ -27,6 +27,14 @@ 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;
+#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-3.2.1-my/net/ipv4/Kconfig
--- linux-3.2.1-orig/net/ipv4/Kconfig        2012-01-12 20:42:45.000000000 +0100
+++ linux-3.2.1-my/net/ipv4/Kconfig        2012-01-16 12:37:00.000000000 +0100
@@ -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-3.2.1-my/net/ipv4/ip_gre.c
--- linux-3.2.1-orig/net/ipv4/ip_gre.c        2012-01-12 20:42:45.000000000 +0100
+++ linux-3.2.1-my/net/ipv4/ip_gre.c        2012-01-17 22:58:43.000000000 +0100
+        __be32 source,
         struct ip_tunnel *tunnel;
         int    offset = 4;
         __be16 gre_proto;
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+        __be32 orig_source;
+        struct hlist_head *head;
+        struct ipgre_tap_bridge_entry *entry;
+        const struct ethhdr *tethhdr;
+#endif
 
         if (!pskb_may_pull(skb, 16))
                 goto drop_nolock;
@@ -659,10 +836,38 @@ static int ipgre_rcv(struct sk_buff *skb
                                 tunnel->dev->stats.rx_errors++;
                                 goto drop;
                         }
-
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+                        orig_source = iph->saddr;
+#endif
                         iph = ip_hdr(skb);
         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 +921,15 @@ static netdev_tx_t ipgre_tunnel_xmit(str
                 tiph = &tunnel->parms.iph;
         }
 
-        if ((dst = tiph->daddr) == 0) {
+#ifdef CONFIG_NET_IPGRE_BRIDGE
+        if ((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 +1422,16 @@ 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 +1442,12 @@ 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 +1717,10 @@ 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,
@@ -1705,6 +1938,9 @@ 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;

Eric Dumazet

unread,
Jan 17, 2012, 6:20:02 PM1/17/12
to
Le mardi 17 janvier 2012 à 23:20 +0100, Stefan Gula a écrit :
> From: Stefan Gula <ste...@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 <ste...@gmail.com>
>
> ---
>
> code was merged with Eric Dumazet proposal (all except the reordering
> of orig_source as that needed to be previous value), tested and fixed
> with additional lines in ipgre_tap_netdev_ops struct
>

Sorry, this is buggy (again...)

Its even clearly commented in the code :

/* Warning: All skb pointers will be invalidated! */

>
> if (!pskb_may_pull(skb, 16))
> goto drop_nolock;
> @@ -659,10 +836,38 @@ static int ipgre_rcv(struct sk_buff *skb
> tunnel->dev->stats.rx_errors++;
> goto drop;
> }

At this point, iph can point to freed memory and its dereference can
crash, since pskb_may_pull() can reallocate skb head.

> -
> +#ifdef CONFIG_NET_IPGRE_BRIDGE
> + orig_source = iph->saddr;
> +#endif

Without any doubt, you know here there is a bug.

> iph = ip_hdr(skb);
> skb->protocol = eth_type_trans(skb, tunnel->dev);
> skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);


So if you need orig_source as the previous iph->saddr value, you must
fetch it _before_ the pskb_may_pull()


/* Warning: All skb pointers will be invalidated! */
if (tunnel->dev->type == ARPHRD_ETHER) {
#ifdef CONFIG_NET_IPGRE_BRIDGE
orig_source = iph->saddr; /* must be done before pskb_may_pull() */
#endif
if (!pskb_may_pull(skb, ETH_HLEN)) {
tunnel->dev->stats.rx_length_errors++;
tunnel->dev->stats.rx_errors++;
goto drop;
}

iph = ip_hdr(skb);
...

Stefan Gula

unread,
Jan 17, 2012, 6:40:02 PM1/17/12