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packet: Add pre-defragmentation support for ipv4 fanouts.

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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>
This commit is contained in:
David S. Miller 2011-07-05 01:43:20 -07:00
parent 595fc71baa
commit 7736d33f42
2 changed files with 49 additions and 2 deletions
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1
include/linux/if_packet.h
View File

@ -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;

50
net/packet/af_packet.c
View File

@ -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);