af_packet: don't emit packet on orig fanout group

If a packet is emitted on one socket in one group of fanout sockets,
it is transmitted again. It is thus read again on one of the sockets
of the fanout group. This result in a loop for software which
generate packets when receiving one.
This retransmission is not the intended behavior: a fanout group
must behave like a single socket. The packet should not be
transmitted on a socket if it originates from a socket belonging
to the same fanout group.

This patch fixes the issue by changing the transmission check to
take fanout group info account.

Reported-by: Aleksandr Kotov <a1k@mail.ru>
Signed-off-by: Eric Leblond <eric@regit.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 3560d688161ebf31ba84130f7aa8decf5fb672f4..59dc05f382475d67d5d4326c852f3b7d49332e3b 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1522,6 +1522,8 @@ struct packet_type {
        struct sk_buff          **(*gro_receive)(struct sk_buff **head,
                                               struct sk_buff *skb);
        int                     (*gro_complete)(struct sk_buff *skb);
+       bool                    (*id_match)(struct packet_type *ptype,
+                                           struct sock *sk);
        void                    *af_packet_priv;
        struct list_head        list;
 };

diff --git a/net/core/dev.c b/net/core/dev.c
index a39354ee14322e5b300646f3866329d22fc20bc8..debd9372472fac64cfb7764570efe1e2a25f4e4c 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1642,6 +1642,19 @@ static inline int deliver_skb(struct sk_buff *skb,
        return pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
 }
 
+static inline bool skb_loop_sk(struct packet_type *ptype, struct sk_buff *skb)
+{
+       if (ptype->af_packet_priv == NULL)
+               return false;
+
+       if (ptype->id_match)
+               return ptype->id_match(ptype, skb->sk);
+       else if ((struct sock *)ptype->af_packet_priv == skb->sk)
+               return true;
+
+       return false;
+}
+
 /*
  *     Support routine. Sends outgoing frames to any network
  *     taps currently in use.
@@ -1659,8 +1672,7 @@ static void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)
                 * they originated from - MvS (miquels@drinkel.ow.org)
                 */
                if ((ptype->dev == dev || !ptype->dev) &&
-                   (ptype->af_packet_priv == NULL ||
-                    (struct sock *)ptype->af_packet_priv != skb->sk)) {
+                   (!skb_loop_sk(ptype, skb))) {
                        if (pt_prev) {
                                deliver_skb(skb2, pt_prev, skb->dev);
                                pt_prev = ptype;

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 8ac890a1a4c069ceead839f1cd4c71b473056291..aee7196aac36c990eedfc7b494a04351c29bb167 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1273,6 +1273,14 @@ static void __fanout_unlink(struct sock *sk, struct packet_sock *po)
        spin_unlock(&f->lock);
 }
 
+bool match_fanout_group(struct packet_type *ptype, struct sock * sk)
+{
+       if (ptype->af_packet_priv == (void*)((struct packet_sock *)sk)->fanout)
+               return true;
+
+       return false;
+}
+
 static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
 {
        struct packet_sock *po = pkt_sk(sk);
@@ -1325,6 +1333,7 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
                match->prot_hook.dev = po->prot_hook.dev;
                match->prot_hook.func = packet_rcv_fanout;
                match->prot_hook.af_packet_priv = match;
+               match->prot_hook.id_match = match_fanout_group;
                dev_add_pack(&match->prot_hook);
                list_add(&match->list, &fanout_list);
        }