Commit 7736d33f authored by David S. Miller's avatar David S. Miller
Browse files

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: default avatarDavid S. Miller <davem@davemloft.net>
parent 595fc71b

include/linux/if_packet.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

net/packet/af_packet.c

+48 −2
Original line number Diff line number Diff line
@@ -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);