packet: Add pre-defragmentation support for ipv4 fanouts.

The skb->rxhash cannot be properly computed if the
packet is a fragment.  To alleviate this, allow the
AF_PACKET client to ask for defragmentation to be
done at demux time.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/if_packet.h b/include/linux/if_packet.h
index 1efa1cb827f52b4d5d14ce265bd6a3353307bdbc..84e684e6935c54aa61d513186bdbdcada4b00740 100644 (file)
--- a/include/linux/if_packet.h
+++ b/include/linux/if_packet.h
@@ -53,6 +53,7 @@ struct sockaddr_ll {
 
 #define PACKET_FANOUT_HASH             0
 #define PACKET_FANOUT_LB               1
+#define PACKET_FANOUT_FLAG_DEFRAG      0x8000
 
 struct tpacket_stats {
        unsigned int    tp_packets;

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 3350f1d3c9aa4840e0dad93e8cb395ea09345f3b..7ba6871a1942d1e622058d918f5d47b87ca0f44d 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -223,7 +223,7 @@ struct packet_fanout {
        unsigned int            num_members;
        u16                     id;
        u8                      type;
-       u8                      pad;
+       u8                      defrag;
        atomic_t                rr_cur;
        struct list_head        list;
        struct sock             *arr[PACKET_FANOUT_MAX];
@@ -447,6 +447,41 @@ static struct sock *fanout_demux_lb(struct packet_fanout *f, struct sk_buff *skb
        return f->arr[cur];
 }
 
+static struct sk_buff *fanout_check_defrag(struct sk_buff *skb)
+{
+       const struct iphdr *iph;
+       u32 len;
+
+       if (skb->protocol != htons(ETH_P_IP))
+               return skb;
+
+       if (!pskb_may_pull(skb, sizeof(struct iphdr)))
+               return skb;
+
+       iph = ip_hdr(skb);
+       if (iph->ihl < 5 || iph->version != 4)
+               return skb;
+       if (!pskb_may_pull(skb, iph->ihl*4))
+               return skb;
+       iph = ip_hdr(skb);
+       len = ntohs(iph->tot_len);
+       if (skb->len < len || len < (iph->ihl * 4))
+               return skb;
+
+       if (ip_is_fragment(ip_hdr(skb))) {
+               skb = skb_clone(skb, GFP_ATOMIC);
+               if (skb) {
+                       if (pskb_trim_rcsum(skb, len))
+                               return skb;
+                       memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
+                       if (ip_defrag(skb, IP_DEFRAG_AF_PACKET))
+                               return NULL;
+                       skb->rxhash = 0;
+               }
+       }
+       return skb;
+}
+
 static int packet_rcv_fanout_hash(struct sk_buff *skb, struct net_device *dev,
                                  struct packet_type *pt, struct net_device *orig_dev)
 {
@@ -461,6 +496,12 @@ static int packet_rcv_fanout_hash(struct sk_buff *skb, struct net_device *dev,
                return 0;
        }
 
+       if (f->defrag) {
+               skb = fanout_check_defrag(skb);
+               if (!skb)
+                       return 0;
+       }
+
        skb_get_rxhash(skb);
 
        sk = fanout_demux_hash(f, skb, num);
@@ -519,10 +560,12 @@ static void __fanout_unlink(struct sock *sk, struct packet_sock *po)
        spin_unlock(&f->lock);
 }
 
-static int fanout_add(struct sock *sk, u16 id, u8 type)
+static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
 {
        struct packet_sock *po = pkt_sk(sk);
        struct packet_fanout *f, *match;
+       u8 type = type_flags & 0xff;
+       u8 defrag = (type_flags & PACKET_FANOUT_FLAG_DEFRAG) ? 1 : 0;
        int err;
 
        switch (type) {
@@ -548,12 +591,15 @@ static int fanout_add(struct sock *sk, u16 id, u8 type)
                        break;
                }
        }
+       if (match && match->defrag != defrag)
+               return -EINVAL;
        if (!match) {
                match = kzalloc(sizeof(*match), GFP_KERNEL);
                if (match) {
                        write_pnet(&match->net, sock_net(sk));
                        match->id = id;
                        match->type = type;
+                       match->defrag = defrag;
                        atomic_set(&match->rr_cur, 0);
                        INIT_LIST_HEAD(&match->list);
                        spin_lock_init(&match->lock);