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

From: Eric Dumazet
Date: Mon Jan 16 2012 - 08:20:13 EST

Le lundi 16 janvier 2012 Ã 13:13 +0100, Åtefan Gula a Ãcrit :
> From: Stefan Gula <steweg@xxxxxxxxx
>
> 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 <steweg@xxxxxxxxx>
>
> ---
>
> 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 ?

> 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 <steweg@xxxxxxxxx>
> + */
> +struct mac_addr {
> + unsigned char addr[6];

Not sure if you need a 'struct mac_addr' for this...

unsigned char mac_addr[ETH_ALEN] ?
> +};
> +
> +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);

You can now use kfree_rcu() and get rid of 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;
> +}
> +

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 ?

> + 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);

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 ?



> +}
> +
> +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) {

if (!is_multicast_ether_addr(tethhdr->h_source)) ?

> + 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(

please format like this :

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

> + 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 = {
>


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