packet: Add fanout support.
Fanouts allow packet capturing to be demuxed to a set of AF_PACKET sockets. Two fanout policies are implemented: 1) Hashing based upon skb->rxhash 2) Pure round-robin An AF_PACKET socket must be fully bound before it tries to add itself to a fanout. All AF_PACKET sockets trying to join the same fanout must all have the same bind settings. Fanouts are identified (within a network namespace) by a 16-bit ID. The first socket to try to add itself to a fanout with a particular ID, creates that fanout. When the last socket leaves the fanout (which happens only when the socket is closed), that fanout is destroyed. Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller
parent
ce06b03e60
commit
dc99f60069
@ -49,6 +49,10 @@ struct sockaddr_ll {
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#define PACKET_VNET_HDR 15
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#define PACKET_TX_TIMESTAMP 16
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#define PACKET_TIMESTAMP 17
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#define PACKET_FANOUT 18
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#define PACKET_FANOUT_HASH 0
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#define PACKET_FANOUT_LB 1
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struct tpacket_stats {
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unsigned int tp_packets;
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@ -187,9 +187,11 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg);
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static void packet_flush_mclist(struct sock *sk);
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struct packet_fanout;
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struct packet_sock {
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/* struct sock has to be the first member of packet_sock */
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struct sock sk;
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struct packet_fanout *fanout;
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struct tpacket_stats stats;
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struct packet_ring_buffer rx_ring;
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struct packet_ring_buffer tx_ring;
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@ -212,6 +214,24 @@ struct packet_sock {
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struct packet_type prot_hook ____cacheline_aligned_in_smp;
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};
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#define PACKET_FANOUT_MAX 256
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struct packet_fanout {
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#ifdef CONFIG_NET_NS
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struct net *net;
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#endif
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unsigned int num_members;
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u16 id;
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u8 type;
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u8 pad;
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atomic_t rr_cur;
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struct list_head list;
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struct sock *arr[PACKET_FANOUT_MAX];
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spinlock_t lock;
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atomic_t sk_ref;
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struct packet_type prot_hook ____cacheline_aligned_in_smp;
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};
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struct packet_skb_cb {
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unsigned int origlen;
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union {
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@ -227,6 +247,9 @@ static inline struct packet_sock *pkt_sk(struct sock *sk)
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return (struct packet_sock *)sk;
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}
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static void __fanout_unlink(struct sock *sk, struct packet_sock *po);
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static void __fanout_link(struct sock *sk, struct packet_sock *po);
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/* register_prot_hook must be invoked with the po->bind_lock held,
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* or from a context in which asynchronous accesses to the packet
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* socket is not possible (packet_create()).
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@ -235,7 +258,10 @@ static void register_prot_hook(struct sock *sk)
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{
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struct packet_sock *po = pkt_sk(sk);
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if (!po->running) {
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dev_add_pack(&po->prot_hook);
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if (po->fanout)
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__fanout_link(sk, po);
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else
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dev_add_pack(&po->prot_hook);
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sock_hold(sk);
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po->running = 1;
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}
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@ -253,7 +279,10 @@ static void __unregister_prot_hook(struct sock *sk, bool sync)
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struct packet_sock *po = pkt_sk(sk);
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po->running = 0;
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__dev_remove_pack(&po->prot_hook);
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if (po->fanout)
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__fanout_unlink(sk, po);
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else
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__dev_remove_pack(&po->prot_hook);
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__sock_put(sk);
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if (sync) {
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@ -388,6 +417,201 @@ static void packet_sock_destruct(struct sock *sk)
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sk_refcnt_debug_dec(sk);
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}
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static int fanout_rr_next(struct packet_fanout *f, unsigned int num)
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{
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int x = atomic_read(&f->rr_cur) + 1;
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if (x >= num)
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x = 0;
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return x;
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}
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static struct sock *fanout_demux_hash(struct packet_fanout *f, struct sk_buff *skb, unsigned int num)
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{
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u32 idx, hash = skb->rxhash;
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idx = ((u64)hash * num) >> 32;
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return f->arr[idx];
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}
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static struct sock *fanout_demux_lb(struct packet_fanout *f, struct sk_buff *skb, unsigned int num)
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{
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int cur, old;
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cur = atomic_read(&f->rr_cur);
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while ((old = atomic_cmpxchg(&f->rr_cur, cur,
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fanout_rr_next(f, num))) != cur)
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cur = old;
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return f->arr[cur];
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}
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static int packet_rcv_fanout_hash(struct sk_buff *skb, struct net_device *dev,
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struct packet_type *pt, struct net_device *orig_dev)
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{
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struct packet_fanout *f = pt->af_packet_priv;
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unsigned int num = f->num_members;
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struct packet_sock *po;
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struct sock *sk;
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if (!net_eq(dev_net(dev), read_pnet(&f->net)) ||
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!num) {
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kfree_skb(skb);
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return 0;
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}
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skb_get_rxhash(skb);
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sk = fanout_demux_hash(f, skb, num);
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po = pkt_sk(sk);
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return po->prot_hook.func(skb, dev, &po->prot_hook, orig_dev);
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}
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static int packet_rcv_fanout_lb(struct sk_buff *skb, struct net_device *dev,
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struct packet_type *pt, struct net_device *orig_dev)
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{
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struct packet_fanout *f = pt->af_packet_priv;
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unsigned int num = f->num_members;
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struct packet_sock *po;
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struct sock *sk;
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if (!net_eq(dev_net(dev), read_pnet(&f->net)) ||
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!num) {
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kfree_skb(skb);
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return 0;
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}
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sk = fanout_demux_lb(f, skb, num);
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po = pkt_sk(sk);
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return po->prot_hook.func(skb, dev, &po->prot_hook, orig_dev);
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}
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static DEFINE_MUTEX(fanout_mutex);
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static LIST_HEAD(fanout_list);
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static void __fanout_link(struct sock *sk, struct packet_sock *po)
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{
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struct packet_fanout *f = po->fanout;
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spin_lock(&f->lock);
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f->arr[f->num_members] = sk;
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smp_wmb();
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f->num_members++;
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spin_unlock(&f->lock);
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}
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static void __fanout_unlink(struct sock *sk, struct packet_sock *po)
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{
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struct packet_fanout *f = po->fanout;
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int i;
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spin_lock(&f->lock);
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for (i = 0; i < f->num_members; i++) {
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if (f->arr[i] == sk)
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break;
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}
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BUG_ON(i >= f->num_members);
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f->arr[i] = f->arr[f->num_members - 1];
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f->num_members--;
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spin_unlock(&f->lock);
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}
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static int fanout_add(struct sock *sk, u16 id, u8 type)
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{
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struct packet_sock *po = pkt_sk(sk);
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struct packet_fanout *f, *match;
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int err;
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switch (type) {
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case PACKET_FANOUT_HASH:
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case PACKET_FANOUT_LB:
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break;
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default:
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return -EINVAL;
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}
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if (!po->running)
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return -EINVAL;
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if (po->fanout)
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return -EALREADY;
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mutex_lock(&fanout_mutex);
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match = NULL;
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list_for_each_entry(f, &fanout_list, list) {
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if (f->id == id &&
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read_pnet(&f->net) == sock_net(sk)) {
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match = f;
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break;
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}
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}
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if (!match) {
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match = kzalloc(sizeof(*match), GFP_KERNEL);
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if (match) {
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write_pnet(&match->net, sock_net(sk));
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match->id = id;
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match->type = type;
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atomic_set(&match->rr_cur, 0);
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INIT_LIST_HEAD(&match->list);
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spin_lock_init(&match->lock);
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atomic_set(&match->sk_ref, 0);
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match->prot_hook.type = po->prot_hook.type;
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match->prot_hook.dev = po->prot_hook.dev;
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switch (type) {
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case PACKET_FANOUT_HASH:
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match->prot_hook.func = packet_rcv_fanout_hash;
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break;
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case PACKET_FANOUT_LB:
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match->prot_hook.func = packet_rcv_fanout_lb;
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break;
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}
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match->prot_hook.af_packet_priv = match;
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dev_add_pack(&match->prot_hook);
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list_add(&match->list, &fanout_list);
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}
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}
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err = -ENOMEM;
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if (match) {
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err = -EINVAL;
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if (match->type == type &&
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match->prot_hook.type == po->prot_hook.type &&
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match->prot_hook.dev == po->prot_hook.dev) {
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err = -ENOSPC;
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if (atomic_read(&match->sk_ref) < PACKET_FANOUT_MAX) {
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__dev_remove_pack(&po->prot_hook);
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po->fanout = match;
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atomic_inc(&match->sk_ref);
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__fanout_link(sk, po);
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err = 0;
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}
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}
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}
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mutex_unlock(&fanout_mutex);
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return err;
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}
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static void fanout_release(struct sock *sk)
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{
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struct packet_sock *po = pkt_sk(sk);
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struct packet_fanout *f;
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f = po->fanout;
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if (!f)
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return;
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po->fanout = NULL;
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mutex_lock(&fanout_mutex);
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if (atomic_dec_and_test(&f->sk_ref)) {
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list_del(&f->list);
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dev_remove_pack(&f->prot_hook);
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kfree(f);
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}
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mutex_unlock(&fanout_mutex);
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}
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static const struct proto_ops packet_ops;
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@ -1398,6 +1622,8 @@ static int packet_release(struct socket *sock)
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if (po->tx_ring.pg_vec)
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packet_set_ring(sk, &req, 1, 1);
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fanout_release(sk);
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synchronize_net();
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/*
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* Now the socket is dead. No more input will appear.
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@ -1421,9 +1647,9 @@ static int packet_release(struct socket *sock)
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static int packet_do_bind(struct sock *sk, struct net_device *dev, __be16 protocol)
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{
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struct packet_sock *po = pkt_sk(sk);
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/*
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* Detach an existing hook if present.
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*/
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if (po->fanout)
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return -EINVAL;
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lock_sock(sk);
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@ -2133,6 +2359,17 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv
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po->tp_tstamp = val;
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return 0;
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}
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case PACKET_FANOUT:
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{
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int val;
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if (optlen != sizeof(val))
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return -EINVAL;
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if (copy_from_user(&val, optval, sizeof(val)))
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return -EFAULT;
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return fanout_add(sk, val & 0xffff, val >> 16);
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}
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default:
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return -ENOPROTOOPT;
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}
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@ -2231,6 +2468,15 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
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val = po->tp_tstamp;
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data = &val;
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break;
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case PACKET_FANOUT:
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if (len > sizeof(int))
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len = sizeof(int);
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val = (po->fanout ?
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((u32)po->fanout->id |
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((u32)po->fanout->type << 16)) :
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0);
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data = &val;
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break;
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default:
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return -ENOPROTOOPT;
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}
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