1 files changed, 804 insertions, 96 deletions

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 1e3fd5bfcd86..12ac6b47a35c 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -3,6 +3,7 @@
  *
  * 		Authors:	Alan Cox <alan@lxorguk.ukuu.org.uk>
  * 				Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
+ * 				Patrick McHardy <kaber@trash.net>
  *
  *		This program is free software; you can redistribute it and/or
  *		modify it under the terms of the GNU General Public License
@@ -55,87 +56,45 @@
 #include <linux/types.h>
 #include <linux/audit.h>
 #include <linux/mutex.h>
+#include <linux/vmalloc.h>
+#include <asm/cacheflush.h>
 
 #include <net/net_namespace.h>
 #include <net/sock.h>
 #include <net/scm.h>
 #include <net/netlink.h>
 
-#define NLGRPSZ(x)	(ALIGN(x, sizeof(unsigned long) * 8) / 8)
-#define NLGRPLONGS(x)	(NLGRPSZ(x)/sizeof(unsigned long))
-
-struct netlink_sock {
-	/* struct sock has to be the first member of netlink_sock */
-	struct sock		sk;
-	u32			portid;
-	u32			dst_portid;
-	u32			dst_group;
-	u32			flags;
-	u32			subscriptions;
-	u32			ngroups;
-	unsigned long		*groups;
-	unsigned long		state;
-	wait_queue_head_t	wait;
-	struct netlink_callback	*cb;
-	struct mutex		*cb_mutex;
-	struct mutex		cb_def_mutex;
-	void			(*netlink_rcv)(struct sk_buff *skb);
-	void			(*netlink_bind)(int group);
-	struct module		*module;
-};
+#include "af_netlink.h"
 
 struct listeners {
 	struct rcu_head		rcu;
 	unsigned long		masks[0];
 };
 
+/* state bits */
+#define NETLINK_CONGESTED	0x0
+
+/* flags */
 #define NETLINK_KERNEL_SOCKET	0x1
 #define NETLINK_RECV_PKTINFO	0x2
 #define NETLINK_BROADCAST_SEND_ERROR	0x4
 #define NETLINK_RECV_NO_ENOBUFS	0x8
 
-static inline struct netlink_sock *nlk_sk(struct sock *sk)
-{
-	return container_of(sk, struct netlink_sock, sk);
-}
-
 static inline int netlink_is_kernel(struct sock *sk)
 {
 	return nlk_sk(sk)->flags & NETLINK_KERNEL_SOCKET;
 }
 
-struct nl_portid_hash {
-	struct hlist_head	*table;
-	unsigned long		rehash_time;
-
-	unsigned int		mask;
-	unsigned int		shift;
-
-	unsigned int		entries;
-	unsigned int		max_shift;
-
-	u32			rnd;
-};
-
-struct netlink_table {
-	struct nl_portid_hash	hash;
-	struct hlist_head	mc_list;
-	struct listeners __rcu	*listeners;
-	unsigned int		flags;
-	unsigned int		groups;
-	struct mutex		*cb_mutex;
-	struct module		*module;
-	void			(*bind)(int group);
-	int			registered;
-};
-
-static struct netlink_table *nl_table;
+struct netlink_table *nl_table;
+EXPORT_SYMBOL_GPL(nl_table);
 
 static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait);
 
 static int netlink_dump(struct sock *sk);
+static void netlink_skb_destructor(struct sk_buff *skb);
 
-static DEFINE_RWLOCK(nl_table_lock);
+DEFINE_RWLOCK(nl_table_lock);
+EXPORT_SYMBOL_GPL(nl_table_lock);
 static atomic_t nl_table_users = ATOMIC_INIT(0);
 
 #define nl_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&nl_table_lock));
@@ -152,6 +111,599 @@ static inline struct hlist_head *nl_portid_hashfn(struct nl_portid_hash *hash, u
 	return &hash->table[jhash_1word(portid, hash->rnd) & hash->mask];
 }
 
+static void netlink_overrun(struct sock *sk)
+{
+	struct netlink_sock *nlk = nlk_sk(sk);
+
+	if (!(nlk->flags & NETLINK_RECV_NO_ENOBUFS)) {
+		if (!test_and_set_bit(NETLINK_CONGESTED, &nlk_sk(sk)->state)) {
+			sk->sk_err = ENOBUFS;
+			sk->sk_error_report(sk);
+		}
+	}
+	atomic_inc(&sk->sk_drops);
+}
+
+static void netlink_rcv_wake(struct sock *sk)
+{
+	struct netlink_sock *nlk = nlk_sk(sk);
+
+	if (skb_queue_empty(&sk->sk_receive_queue))
+		clear_bit(NETLINK_CONGESTED, &nlk->state);
+	if (!test_bit(NETLINK_CONGESTED, &nlk->state))
+		wake_up_interruptible(&nlk->wait);
+}
+
+#ifdef CONFIG_NETLINK_MMAP
+static bool netlink_skb_is_mmaped(const struct sk_buff *skb)
+{
+	return NETLINK_CB(skb).flags & NETLINK_SKB_MMAPED;
+}
+
+static bool netlink_rx_is_mmaped(struct sock *sk)
+{
+	return nlk_sk(sk)->rx_ring.pg_vec != NULL;
+}
+
+static bool netlink_tx_is_mmaped(struct sock *sk)
+{
+	return nlk_sk(sk)->tx_ring.pg_vec != NULL;
+}
+
+static __pure struct page *pgvec_to_page(const void *addr)
+{
+	if (is_vmalloc_addr(addr))
+		return vmalloc_to_page(addr);
+	else
+		return virt_to_page(addr);
+}
+
+static void free_pg_vec(void **pg_vec, unsigned int order, unsigned int len)
+{
+	unsigned int i;
+
+	for (i = 0; i < len; i++) {
+		if (pg_vec[i] != NULL) {
+			if (is_vmalloc_addr(pg_vec[i]))
+				vfree(pg_vec[i]);
+			else
+				free_pages((unsigned long)pg_vec[i], order);
+		}
+	}
+	kfree(pg_vec);
+}
+
+static void *alloc_one_pg_vec_page(unsigned long order)
+{
+	void *buffer;
+	gfp_t gfp_flags = GFP_KERNEL | __GFP_COMP | __GFP_ZERO |
+			  __GFP_NOWARN | __GFP_NORETRY;
+
+	buffer = (void *)__get_free_pages(gfp_flags, order);
+	if (buffer != NULL)
+		return buffer;
+
+	buffer = vzalloc((1 << order) * PAGE_SIZE);
+	if (buffer != NULL)
+		return buffer;
+
+	gfp_flags &= ~__GFP_NORETRY;
+	return (void *)__get_free_pages(gfp_flags, order);
+}
+
+static void **alloc_pg_vec(struct netlink_sock *nlk,
+			   struct nl_mmap_req *req, unsigned int order)
+{
+	unsigned int block_nr = req->nm_block_nr;
+	unsigned int i;
+	void **pg_vec, *ptr;
+
+	pg_vec = kcalloc(block_nr, sizeof(void *), GFP_KERNEL);
+	if (pg_vec == NULL)
+		return NULL;
+
+	for (i = 0; i < block_nr; i++) {
+		pg_vec[i] = ptr = alloc_one_pg_vec_page(order);
+		if (pg_vec[i] == NULL)
+			goto err1;
+	}
+
+	return pg_vec;
+err1:
+	free_pg_vec(pg_vec, order, block_nr);
+	return NULL;
+}
+
+static int netlink_set_ring(struct sock *sk, struct nl_mmap_req *req,
+			    bool closing, bool tx_ring)
+{
+	struct netlink_sock *nlk = nlk_sk(sk);
+	struct netlink_ring *ring;
+	struct sk_buff_head *queue;
+	void **pg_vec = NULL;
+	unsigned int order = 0;
+	int err;
+
+	ring  = tx_ring ? &nlk->tx_ring : &nlk->rx_ring;
+	queue = tx_ring ? &sk->sk_write_queue : &sk->sk_receive_queue;
+
+	if (!closing) {
+		if (atomic_read(&nlk->mapped))
+			return -EBUSY;
+		if (atomic_read(&ring->pending))
+			return -EBUSY;
+	}
+
+	if (req->nm_block_nr) {
+		if (ring->pg_vec != NULL)
+			return -EBUSY;
+
+		if ((int)req->nm_block_size <= 0)
+			return -EINVAL;
+		if (!IS_ALIGNED(req->nm_block_size, PAGE_SIZE))
+			return -EINVAL;
+		if (req->nm_frame_size < NL_MMAP_HDRLEN)
+			return -EINVAL;
+		if (!IS_ALIGNED(req->nm_frame_size, NL_MMAP_MSG_ALIGNMENT))
+			return -EINVAL;
+
+		ring->frames_per_block = req->nm_block_size /
+					 req->nm_frame_size;
+		if (ring->frames_per_block == 0)
+			return -EINVAL;
+		if (ring->frames_per_block * req->nm_block_nr !=
+		    req->nm_frame_nr)
+			return -EINVAL;
+
+		order = get_order(req->nm_block_size);
+		pg_vec = alloc_pg_vec(nlk, req, order);
+		if (pg_vec == NULL)
+			return -ENOMEM;
+	} else {
+		if (req->nm_frame_nr)
+			return -EINVAL;
+	}
+
+	err = -EBUSY;
+	mutex_lock(&nlk->pg_vec_lock);
+	if (closing || atomic_read(&nlk->mapped) == 0) {
+		err = 0;
+		spin_lock_bh(&queue->lock);
+
+		ring->frame_max		= req->nm_frame_nr - 1;
+		ring->head		= 0;
+		ring->frame_size	= req->nm_frame_size;
+		ring->pg_vec_pages	= req->nm_block_size / PAGE_SIZE;
+
+		swap(ring->pg_vec_len, req->nm_block_nr);
+		swap(ring->pg_vec_order, order);
+		swap(ring->pg_vec, pg_vec);
+
+		__skb_queue_purge(queue);
+		spin_unlock_bh(&queue->lock);
+
+		WARN_ON(atomic_read(&nlk->mapped));
+	}
+	mutex_unlock(&nlk->pg_vec_lock);
+
+	if (pg_vec)
+		free_pg_vec(pg_vec, order, req->nm_block_nr);
+	return err;
+}
+
+static void netlink_mm_open(struct vm_area_struct *vma)
+{
+	struct file *file = vma->vm_file;
+	struct socket *sock = file->private_data;
+	struct sock *sk = sock->sk;
+
+	if (sk)
+		atomic_inc(&nlk_sk(sk)->mapped);
+}
+
+static void netlink_mm_close(struct vm_area_struct *vma)
+{
+	struct file *file = vma->vm_file;
+	struct socket *sock = file->private_data;
+	struct sock *sk = sock->sk;
+
+	if (sk)
+		atomic_dec(&nlk_sk(sk)->mapped);
+}
+
+static const struct vm_operations_struct netlink_mmap_ops = {
+	.open	= netlink_mm_open,
+	.close	= netlink_mm_close,
+};
+
+static int netlink_mmap(struct file *file, struct socket *sock,
+			struct vm_area_struct *vma)
+{
+	struct sock *sk = sock->sk;
+	struct netlink_sock *nlk = nlk_sk(sk);
+	struct netlink_ring *ring;
+	unsigned long start, size, expected;
+	unsigned int i;
+	int err = -EINVAL;
+
+	if (vma->vm_pgoff)
+		return -EINVAL;
+
+	mutex_lock(&nlk->pg_vec_lock);
+
+	expected = 0;
+	for (ring = &nlk->rx_ring; ring <= &nlk->tx_ring; ring++) {
+		if (ring->pg_vec == NULL)
+			continue;
+		expected += ring->pg_vec_len * ring->pg_vec_pages * PAGE_SIZE;
+	}
+
+	if (expected == 0)
+		goto out;
+
+	size = vma->vm_end - vma->vm_start;
+	if (size != expected)
+		goto out;
+
+	start = vma->vm_start;
+	for (ring = &nlk->rx_ring; ring <= &nlk->tx_ring; ring++) {
+		if (ring->pg_vec == NULL)
+			continue;
+
+		for (i = 0; i < ring->pg_vec_len; i++) {
+			struct page *page;
+			void *kaddr = ring->pg_vec[i];
+			unsigned int pg_num;
+
+			for (pg_num = 0; pg_num < ring->pg_vec_pages; pg_num++) {
+				page = pgvec_to_page(kaddr);
+				err = vm_insert_page(vma, start, page);
+				if (err < 0)
+					goto out;
+				start += PAGE_SIZE;
+				kaddr += PAGE_SIZE;
+			}
+		}
+	}
+
+	atomic_inc(&nlk->mapped);
+	vma->vm_ops = &netlink_mmap_ops;
+	err = 0;
+out:
+	mutex_unlock(&nlk->pg_vec_lock);
+	return 0;
+}
+
+static void netlink_frame_flush_dcache(const struct nl_mmap_hdr *hdr)
+{
+#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE == 1
+	struct page *p_start, *p_end;
+
+	/* First page is flushed through netlink_{get,set}_status */
+	p_start = pgvec_to_page(hdr + PAGE_SIZE);
+	p_end   = pgvec_to_page((void *)hdr + NL_MMAP_HDRLEN + hdr->nm_len - 1);
+	while (p_start <= p_end) {
+		flush_dcache_page(p_start);
+		p_start++;
+	}
+#endif
+}
+
+static enum nl_mmap_status netlink_get_status(const struct nl_mmap_hdr *hdr)
+{
+	smp_rmb();
+	flush_dcache_page(pgvec_to_page(hdr));
+	return hdr->nm_status;
+}
+
+static void netlink_set_status(struct nl_mmap_hdr *hdr,
+			       enum nl_mmap_status status)
+{
+	hdr->nm_status = status;
+	flush_dcache_page(pgvec_to_page(hdr));
+	smp_wmb();
+}
+
+static struct nl_mmap_hdr *
+__netlink_lookup_frame(const struct netlink_ring *ring, unsigned int pos)
+{
+	unsigned int pg_vec_pos, frame_off;
+
+	pg_vec_pos = pos / ring->frames_per_block;
+	frame_off  = pos % ring->frames_per_block;
+
+	return ring->pg_vec[pg_vec_pos] + (frame_off * ring->frame_size);
+}
+
+static struct nl_mmap_hdr *
+netlink_lookup_frame(const struct netlink_ring *ring, unsigned int pos,
+		     enum nl_mmap_status status)
+{
+	struct nl_mmap_hdr *hdr;
+
+	hdr = __netlink_lookup_frame(ring, pos);
+	if (netlink_get_status(hdr) != status)
+		return NULL;
+
+	return hdr;
+}
+
+static struct nl_mmap_hdr *
+netlink_current_frame(const struct netlink_ring *ring,
+		      enum nl_mmap_status status)
+{
+	return netlink_lookup_frame(ring, ring->head, status);
+}
+
+static struct nl_mmap_hdr *
+netlink_previous_frame(const struct netlink_ring *ring,
+		       enum nl_mmap_status status)
+{
+	unsigned int prev;
+
+	prev = ring->head ? ring->head - 1 : ring->frame_max;
+	return netlink_lookup_frame(ring, prev, status);
+}
+
+static void netlink_increment_head(struct netlink_ring *ring)
+{
+	ring->head = ring->head != ring->frame_max ? ring->head + 1 : 0;
+}
+
+static void netlink_forward_ring(struct netlink_ring *ring)
+{
+	unsigned int head = ring->head, pos = head;
+	const struct nl_mmap_hdr *hdr;
+
+	do {
+		hdr = __netlink_lookup_frame(ring, pos);
+		if (hdr->nm_status == NL_MMAP_STATUS_UNUSED)
+			break;
+		if (hdr->nm_status != NL_MMAP_STATUS_SKIP)
+			break;
+		netlink_increment_head(ring);
+	} while (ring->head != head);
+}
+
+static bool netlink_dump_space(struct netlink_sock *nlk)
+{
+	struct netlink_ring *ring = &nlk->rx_ring;
+	struct nl_mmap_hdr *hdr;
+	unsigned int n;
+
+	hdr = netlink_current_frame(ring, NL_MMAP_STATUS_UNUSED);
+	if (hdr == NULL)
+		return false;
+
+	n = ring->head + ring->frame_max / 2;
+	if (n > ring->frame_max)
+		n -= ring->frame_max;
+
+	hdr = __netlink_lookup_frame(ring, n);
+
+	return hdr->nm_status == NL_MMAP_STATUS_UNUSED;
+}
+
+static unsigned int netlink_poll(struct file *file, struct socket *sock,
+				 poll_table *wait)
+{
+	struct sock *sk = sock->sk;
+	struct netlink_sock *nlk = nlk_sk(sk);
+	unsigned int mask;
+	int err;
+
+	if (nlk->rx_ring.pg_vec != NULL) {
+		/* Memory mapped sockets don't call recvmsg(), so flow control
+		 * for dumps is performed here. A dump is allowed to continue
+		 * if at least half the ring is unused.
+		 */
+		while (nlk->cb != NULL && netlink_dump_space(nlk)) {
+			err = netlink_dump(sk);
+			if (err < 0) {
+				sk->sk_err = err;
+				sk->sk_error_report(sk);
+				break;
+			}
+		}
+		netlink_rcv_wake(sk);
+	}
+
+	mask = datagram_poll(file, sock, wait);
+
+	spin_lock_bh(&sk->sk_receive_queue.lock);
+	if (nlk->rx_ring.pg_vec) {
+		netlink_forward_ring(&nlk->rx_ring);
+		if (!netlink_previous_frame(&nlk->rx_ring, NL_MMAP_STATUS_UNUSED))
+			mask |= POLLIN | POLLRDNORM;
+	}
+	spin_unlock_bh(&sk->sk_receive_queue.lock);
+
+	spin_lock_bh(&sk->sk_write_queue.lock);
+	if (nlk->tx_ring.pg_vec) {
+		if (netlink_current_frame(&nlk->tx_ring, NL_MMAP_STATUS_UNUSED))
+			mask |= POLLOUT | POLLWRNORM;
+	}
+	spin_unlock_bh(&sk->sk_write_queue.lock);
+
+	return mask;
+}
+
+static struct nl_mmap_hdr *netlink_mmap_hdr(struct sk_buff *skb)
+{
+	return (struct nl_mmap_hdr *)(skb->head - NL_MMAP_HDRLEN);
+}
+
+static void netlink_ring_setup_skb(struct sk_buff *skb, struct sock *sk,
+				   struct netlink_ring *ring,
+				   struct nl_mmap_hdr *hdr)
+{
+	unsigned int size;
+	void *data;
+
+	size = ring->frame_size - NL_MMAP_HDRLEN;
+	data = (void *)hdr + NL_MMAP_HDRLEN;
+
+	skb->head	= data;
+	skb->data	= data;
+	skb_reset_tail_pointer(skb);
+	skb->end	= skb->tail + size;
+	skb->len	= 0;
+
+	skb->destructor	= netlink_skb_destructor;
+	NETLINK_CB(skb).flags |= NETLINK_SKB_MMAPED;
+	NETLINK_CB(skb).sk = sk;
+}
+
+static int netlink_mmap_sendmsg(struct sock *sk, struct msghdr *msg,
+				u32 dst_portid, u32 dst_group,
+				struct sock_iocb *siocb)
+{
+	struct netlink_sock *nlk = nlk_sk(sk);
+	struct netlink_ring *ring;
+	struct nl_mmap_hdr *hdr;
+	struct sk_buff *skb;
+	unsigned int maxlen;
+	bool excl = true;
+	int err = 0, len = 0;
+
+	/* Netlink messages are validated by the receiver before processing.
+	 * In order to avoid userspace changing the contents of the message
+	 * after validation, the socket and the ring may only be used by a
+	 * single process, otherwise we fall back to copying.
+	 */
+	if (atomic_long_read(&sk->sk_socket->file->f_count) > 2 ||
+	    atomic_read(&nlk->mapped) > 1)
+		excl = false;
+
+	mutex_lock(&nlk->pg_vec_lock);
+
+	ring   = &nlk->tx_ring;
+	maxlen = ring->frame_size - NL_MMAP_HDRLEN;
+
+	do {
+		hdr = netlink_current_frame(ring, NL_MMAP_STATUS_VALID);
+		if (hdr == NULL) {
+			if (!(msg->msg_flags & MSG_DONTWAIT) &&
+			    atomic_read(&nlk->tx_ring.pending))
+				schedule();
+			continue;
+		}
+		if (hdr->nm_len > maxlen) {
+			err = -EINVAL;
+			goto out;
+		}
+
+		netlink_frame_flush_dcache(hdr);
+
+		if (likely(dst_portid == 0 && dst_group == 0 && excl)) {
+			skb = alloc_skb_head(GFP_KERNEL);
+			if (skb == NULL) {
+				err = -ENOBUFS;
+				goto out;
+			}
+			sock_hold(sk);
+			netlink_ring_setup_skb(skb, sk, ring, hdr);
+			NETLINK_CB(skb).flags |= NETLINK_SKB_TX;
+			__skb_put(skb, hdr->nm_len);
+			netlink_set_status(hdr, NL_MMAP_STATUS_RESERVED);
+			atomic_inc(&ring->pending);
+		} else {
+			skb = alloc_skb(hdr->nm_len, GFP_KERNEL);
+			if (skb == NULL) {
+				err = -ENOBUFS;
+				goto out;
+			}
+			__skb_put(skb, hdr->nm_len);
+			memcpy(skb->data, (void *)hdr + NL_MMAP_HDRLEN, hdr->nm_len);
+			netlink_set_status(hdr, NL_MMAP_STATUS_UNUSED);
+		}
+
+		netlink_increment_head(ring);
+
+		NETLINK_CB(skb).portid	  = nlk->portid;
+		NETLINK_CB(skb).dst_group = dst_group;
+		NETLINK_CB(skb).creds	  = siocb->scm->creds;
+
+		err = security_netlink_send(sk, skb);
+		if (err) {
+			kfree_skb(skb);
+			goto out;
+		}
+
+		if (unlikely(dst_group)) {
+			atomic_inc(&skb->users);
+			netlink_broadcast(sk, skb, dst_portid, dst_group,
+					  GFP_KERNEL);
+		}
+		err = netlink_unicast(sk, skb, dst_portid,
+				      msg->msg_flags & MSG_DONTWAIT);
+		if (err < 0)
+			goto out;
+		len += err;
+
+	} while (hdr != NULL ||
+		 (!(msg->msg_flags & MSG_DONTWAIT) &&
+		  atomic_read(&nlk->tx_ring.pending)));
+
+	if (len > 0)
+		err = len;
+out:
+	mutex_unlock(&nlk->pg_vec_lock);
+	return err;
+}
+
+static void netlink_queue_mmaped_skb(struct sock *sk, struct sk_buff *skb)
+{
+	struct nl_mmap_hdr *hdr;
+
+	hdr = netlink_mmap_hdr(skb);
+	hdr->nm_len	= skb->len;
+	hdr->nm_group	= NETLINK_CB(skb).dst_group;
+	hdr->nm_pid	= NETLINK_CB(skb).creds.pid;
+	hdr->nm_uid	= from_kuid(sk_user_ns(sk), NETLINK_CB(skb).creds.uid);
+	hdr->nm_gid	= from_kgid(sk_user_ns(sk), NETLINK_CB(skb).creds.gid);
+	netlink_frame_flush_dcache(hdr);
+	netlink_set_status(hdr, NL_MMAP_STATUS_VALID);
+
+	NETLINK_CB(skb).flags |= NETLINK_SKB_DELIVERED;
+	kfree_skb(skb);
+}
+
+static void netlink_ring_set_copied(struct sock *sk, struct sk_buff *skb)
+{
+	struct netlink_sock *nlk = nlk_sk(sk);
+	struct netlink_ring *ring = &nlk->rx_ring;
+	struct nl_mmap_hdr *hdr;
+
+	spin_lock_bh(&sk->sk_receive_queue.lock);
+	hdr = netlink_current_frame(ring, NL_MMAP_STATUS_UNUSED);
+	if (hdr == NULL) {
+		spin_unlock_bh(&sk->sk_receive_queue.lock);
+		kfree_skb(skb);
+		netlink_overrun(sk);
+		return;
+	}
+	netlink_increment_head(ring);
+	__skb_queue_tail(&sk->sk_receive_queue, skb);
+	spin_unlock_bh(&sk->sk_receive_queue.lock);
+
+	hdr->nm_len	= skb->len;
+	hdr->nm_group	= NETLINK_CB(skb).dst_group;
+	hdr->nm_pid	= NETLINK_CB(skb).creds.pid;
+	hdr->nm_uid	= from_kuid(sk_user_ns(sk), NETLINK_CB(skb).creds.uid);
+	hdr->nm_gid	= from_kgid(sk_user_ns(sk), NETLINK_CB(skb).creds.gid);
+	netlink_set_status(hdr, NL_MMAP_STATUS_COPY);
+}
+
+#else /* CONFIG_NETLINK_MMAP */
+#define netlink_skb_is_mmaped(skb)	false
+#define netlink_rx_is_mmaped(sk)	false
+#define netlink_tx_is_mmaped(sk)	false
+#define netlink_mmap			sock_no_mmap
+#define netlink_poll			datagram_poll
+#define netlink_mmap_sendmsg(sk, msg, dst_portid, dst_group, siocb)	0
+#endif /* CONFIG_NETLINK_MMAP */
+
 static void netlink_destroy_callback(struct netlink_callback *cb)
 {
 	kfree_skb(cb->skb);
@@ -164,6 +716,53 @@ static void netlink_consume_callback(struct netlink_callback *cb)
 	kfree(cb);
 }
 
+static void netlink_skb_destructor(struct sk_buff *skb)
+{
+#ifdef CONFIG_NETLINK_MMAP
+	struct nl_mmap_hdr *hdr;
+	struct netlink_ring *ring;
+	struct sock *sk;
+
+	/* If a packet from the kernel to userspace was freed because of an
+	 * error without being delivered to userspace, the kernel must reset
+	 * the status. In the direction userspace to kernel, the status is
+	 * always reset here after the packet was processed and freed.
+	 */
+	if (netlink_skb_is_mmaped(skb)) {
+		hdr = netlink_mmap_hdr(skb);
+		sk = NETLINK_CB(skb).sk;
+
+		if (NETLINK_CB(skb).flags & NETLINK_SKB_TX) {
+			netlink_set_status(hdr, NL_MMAP_STATUS_UNUSED);
+			ring = &nlk_sk(sk)->tx_ring;
+		} else {
+			if (!(NETLINK_CB(skb).flags & NETLINK_SKB_DELIVERED)) {
+				hdr->nm_len = 0;
+				netlink_set_status(hdr, NL_MMAP_STATUS_VALID);
+			}
+			ring = &nlk_sk(sk)->rx_ring;
+		}
+
+		WARN_ON(atomic_read(&ring->pending) == 0);
+		atomic_dec(&ring->pending);
+		sock_put(sk);
+
+		skb->data = NULL;
+	}
+#endif
+	if (skb->sk != NULL)
+		sock_rfree(skb);
+}
+
+static void netlink_skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
+{
+	WARN_ON(skb->sk != NULL);
+	skb->sk = sk;
+	skb->destructor = netlink_skb_destructor;
+	atomic_add(skb->truesize, &sk->sk_rmem_alloc);
+	sk_mem_charge(sk, skb->truesize);
+}
+
 static void netlink_sock_destruct(struct sock *sk)
 {
 	struct netlink_sock *nlk = nlk_sk(sk);
@@ -177,6 +776,18 @@ static void netlink_sock_destruct(struct sock *sk)
 	}
 
 	skb_queue_purge(&sk->sk_receive_queue);
+#ifdef CONFIG_NETLINK_MMAP
+	if (1) {
+		struct nl_mmap_req req;
+
+		memset(&req, 0, sizeof(req));
+		if (nlk->rx_ring.pg_vec)
+			netlink_set_ring(sk, &req, true, false);
+		memset(&req, 0, sizeof(req));
+		if (nlk->tx_ring.pg_vec)
+			netlink_set_ring(sk, &req, true, true);
+	}
+#endif /* CONFIG_NETLINK_MMAP */
 
 	if (!sock_flag(sk, SOCK_DEAD)) {
 		printk(KERN_ERR "Freeing alive netlink socket %p\n", sk);
@@ -440,6 +1051,9 @@ static int __netlink_create(struct net *net, struct socket *sock,
 		mutex_init(nlk->cb_mutex);
 	}
 	init_waitqueue_head(&nlk->wait);
+#ifdef CONFIG_NETLINK_MMAP
+	mutex_init(&nlk->pg_vec_lock);
+#endif
 
 	sk->sk_destruct = netlink_sock_destruct;
 	sk->sk_protocol = protocol;
@@ -771,19 +1385,6 @@ static int netlink_getname(struct socket *sock, struct sockaddr *addr,
 	return 0;
 }
 
-static void netlink_overrun(struct sock *sk)
-{
-	struct netlink_sock *nlk = nlk_sk(sk);
-
-	if (!(nlk->flags & NETLINK_RECV_NO_ENOBUFS)) {
-		if (!test_and_set_bit(0, &nlk_sk(sk)->state)) {
-			sk->sk_err = ENOBUFS;
-			sk->sk_error_report(sk);
-		}
-	}
-	atomic_inc(&sk->sk_drops);
-}
-
 static struct sock *netlink_getsockbyportid(struct sock *ssk, u32 portid)
 {
 	struct sock *sock;
@@ -836,8 +1437,9 @@ int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
 
 	nlk = nlk_sk(sk);
 
-	if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
-	    test_bit(0, &nlk->state)) {
+	if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
+	     test_bit(NETLINK_CONGESTED, &nlk->state)) &&
+	    !netlink_skb_is_mmaped(skb)) {
 		DECLARE_WAITQUEUE(wait, current);
 		if (!*timeo) {
 			if (!ssk || netlink_is_kernel(ssk))
@@ -851,7 +1453,7 @@ int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
 		add_wait_queue(&nlk->wait, &wait);
 
 		if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
-		     test_bit(0, &nlk->state)) &&
+		     test_bit(NETLINK_CONGESTED, &nlk->state)) &&
 		    !sock_flag(sk, SOCK_DEAD))
 			*timeo = schedule_timeout(*timeo);
 
@@ -865,7 +1467,7 @@ int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
 		}
 		return 1;
 	}
-	skb_set_owner_r(skb, sk);
+	netlink_skb_set_owner_r(skb, sk);
 	return 0;
 }
 
@@ -873,7 +1475,14 @@ static int __netlink_sendskb(struct sock *sk, struct sk_buff *skb)
 {
 	int len = skb->len;
 
-	skb_queue_tail(&sk->sk_receive_queue, skb);
+#ifdef CONFIG_NETLINK_MMAP
+	if (netlink_skb_is_mmaped(skb))
+		netlink_queue_mmaped_skb(sk, skb);
+	else if (netlink_rx_is_mmaped(sk))
+		netlink_ring_set_copied(sk, skb);
+	else
+#endif /* CONFIG_NETLINK_MMAP */
+		skb_queue_tail(&sk->sk_receive_queue, skb);
 	sk->sk_data_ready(sk, len);
 	return len;
 }
@@ -896,7 +1505,9 @@ static struct sk_buff *netlink_trim(struct sk_buff *skb, gfp_t allocation)
 {
 	int delta;
 
-	skb_orphan(skb);
+	WARN_ON(skb->sk != NULL);
+	if (netlink_skb_is_mmaped(skb))
+		return skb;
 
 	delta = skb->end - skb->tail;
 	if (delta * 2 < skb->truesize)
@@ -916,16 +1527,6 @@ static struct sk_buff *netlink_trim(struct sk_buff *skb, gfp_t allocation)
 	return skb;
 }
 
-static void netlink_rcv_wake(struct sock *sk)
-{
-	struct netlink_sock *nlk = nlk_sk(sk);
-
-	if (skb_queue_empty(&sk->sk_receive_queue))
-		clear_bit(0, &nlk->state);
-	if (!test_bit(0, &nlk->state))
-		wake_up_interruptible(&nlk->wait);
-}
-
 static int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb,
 				  struct sock *ssk)
 {
@@ -935,8 +1536,8 @@ static int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb,
 	ret = -ECONNREFUSED;
 	if (nlk->netlink_rcv != NULL) {
 		ret = skb->len;
-		skb_set_owner_r(skb, sk);
-		NETLINK_CB(skb).ssk = ssk;
+		netlink_skb_set_owner_r(skb, sk);
+		NETLINK_CB(skb).sk = ssk;
 		nlk->netlink_rcv(skb);
 		consume_skb(skb);
 	} else {
@@ -982,6 +1583,69 @@ retry:
 }
 EXPORT_SYMBOL(netlink_unicast);
 
+struct sk_buff *netlink_alloc_skb(struct sock *ssk, unsigned int size,
+				  u32 dst_portid, gfp_t gfp_mask)
+{
+#ifdef CONFIG_NETLINK_MMAP
+	struct sock *sk = NULL;
+	struct sk_buff *skb;
+	struct netlink_ring *ring;
+	struct nl_mmap_hdr *hdr;
+	unsigned int maxlen;
+
+	sk = netlink_getsockbyportid(ssk, dst_portid);
+	if (IS_ERR(sk))
+		goto out;
+
+	ring = &nlk_sk(sk)->rx_ring;
+	/* fast-path without atomic ops for common case: non-mmaped receiver */
+	if (ring->pg_vec == NULL)
+		goto out_put;
+
+	skb = alloc_skb_head(gfp_mask);
+	if (skb == NULL)
+		goto err1;
+
+	spin_lock_bh(&sk->sk_receive_queue.lock);
+	/* check again under lock */
+	if (ring->pg_vec == NULL)
+		goto out_free;
+
+	maxlen = ring->frame_size - NL_MMAP_HDRLEN;
+	if (maxlen < size)
+		goto out_free;
+
+	netlink_forward_ring(ring);
+	hdr = netlink_current_frame(ring, NL_MMAP_STATUS_UNUSED);
+	if (hdr == NULL)
+		goto err2;
+	netlink_ring_setup_skb(skb, sk, ring, hdr);
+	netlink_set_status(hdr, NL_MMAP_STATUS_RESERVED);
+	atomic_inc(&ring->pending);
+	netlink_increment_head(ring);
+
+	spin_unlock_bh(&sk->sk_receive_queue.lock);
+	return skb;
+
+err2:
+	kfree_skb(skb);
+	spin_unlock_bh(&sk->sk_receive_queue.lock);
+	netlink_overrun(sk);
+err1:
+	sock_put(sk);
+	return NULL;
+
+out_free:
+	kfree_skb(skb);
+	spin_unlock_bh(&sk->sk_receive_queue.lock);
+out_put:
+	sock_put(sk);
+out:
+#endif
+	return alloc_skb(size, gfp_mask);
+}
+EXPORT_SYMBOL_GPL(netlink_alloc_skb);
+
 int netlink_has_listeners(struct sock *sk, unsigned int group)
 {
 	int res = 0;
@@ -1006,8 +1670,8 @@ static int netlink_broadcast_deliver(struct sock *sk, struct sk_buff *skb)
 	struct netlink_sock *nlk = nlk_sk(sk);
 
 	if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf &&
-	    !test_bit(0, &nlk->state)) {
-		skb_set_owner_r(skb, sk);
+	    !test_bit(NETLINK_CONGESTED, &nlk->state)) {
+		netlink_skb_set_owner_r(skb, sk);
 		__netlink_sendskb(sk, skb);
 		return atomic_read(&sk->sk_rmem_alloc) > (sk->sk_rcvbuf >> 1);
 	}
@@ -1242,7 +1906,8 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname,
 	if (level != SOL_NETLINK)
 		return -ENOPROTOOPT;
 
-	if (optlen >= sizeof(int) &&
+	if (optname != NETLINK_RX_RING && optname != NETLINK_TX_RING &&
+	    optlen >= sizeof(int) &&
 	    get_user(val, (unsigned int __user *)optval))
 		return -EFAULT;
 
@@ -1284,13 +1949,32 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname,
 	case NETLINK_NO_ENOBUFS:
 		if (val) {
 			nlk->flags |= NETLINK_RECV_NO_ENOBUFS;
-			clear_bit(0, &nlk->state);
+			clear_bit(NETLINK_CONGESTED, &nlk->state);
 			wake_up_interruptible(&nlk->wait);
 		} else {
 			nlk->flags &= ~NETLINK_RECV_NO_ENOBUFS;
 		}
 		err = 0;
 		break;
+#ifdef CONFIG_NETLINK_MMAP
+	case NETLINK_RX_RING:
+	case NETLINK_TX_RING: {
+		struct nl_mmap_req req;
+
+		/* Rings might consume more memory than queue limits, require
+		 * CAP_NET_ADMIN.
+		 */
+		if (!capable(CAP_NET_ADMIN))
+			return -EPERM;
+		if (optlen < sizeof(req))
+			return -EINVAL;
+		if (copy_from_user(&req, optval, sizeof(req)))
+			return -EFAULT;
+		err = netlink_set_ring(sk, &req, false,
+				       optname == NETLINK_TX_RING);
+		break;
+	}
+#endif /* CONFIG_NETLINK_MMAP */
 	default:
 		err = -ENOPROTOOPT;
 	}
@@ -1401,6 +2085,13 @@ static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock,
 			goto out;
 	}
 
+	if (netlink_tx_is_mmaped(sk) &&
+	    msg->msg_iov->iov_base == NULL) {
+		err = netlink_mmap_sendmsg(sk, msg, dst_portid, dst_group,
+					   siocb);
+		goto out;
+	}
+
 	err = -EMSGSIZE;
 	if (len > sk->sk_sndbuf - 32)
 		goto out;
@@ -1695,7 +2386,7 @@ struct nlmsghdr *
 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags)
 {
 	struct nlmsghdr *nlh;
-	int size = NLMSG_LENGTH(len);
+	int size = nlmsg_msg_size(len);
 
 	nlh = (struct nlmsghdr*)skb_put(skb, NLMSG_ALIGN(size));
 	nlh->nlmsg_type = type;
@@ -1704,7 +2395,7 @@ __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int fla
 	nlh->nlmsg_pid = portid;
 	nlh->nlmsg_seq = seq;
 	if (!__builtin_constant_p(size) || NLMSG_ALIGN(size) - size != 0)
-		memset(NLMSG_DATA(nlh) + len, 0, NLMSG_ALIGN(size) - size);
+		memset(nlmsg_data(nlh) + len, 0, NLMSG_ALIGN(size) - size);
 	return nlh;
 }
 EXPORT_SYMBOL(__nlmsg_put);
@@ -1733,9 +2424,13 @@ static int netlink_dump(struct sock *sk)
 
 	alloc_size = max_t(int, cb->min_dump_alloc, NLMSG_GOODSIZE);
 
-	skb = sock_rmalloc(sk, alloc_size, 0, GFP_KERNEL);
+	if (!netlink_rx_is_mmaped(sk) &&
+	    atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
+		goto errout_skb;
+	skb = netlink_alloc_skb(sk, alloc_size, nlk->portid, GFP_KERNEL);
 	if (!skb)
 		goto errout_skb;
+	netlink_skb_set_owner_r(skb, sk);
 
 	len = cb->dump(skb, cb);
 
@@ -1790,13 +2485,25 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
 	if (cb == NULL)
 		return -ENOBUFS;
 
+	/* Memory mapped dump requests need to be copied to avoid looping
+	 * on the pending state in netlink_mmap_sendmsg() while the CB hold
+	 * a reference to the skb.
+	 */
+	if (netlink_skb_is_mmaped(skb)) {
+		skb = skb_copy(skb, GFP_KERNEL);
+		if (skb == NULL) {
+			kfree(cb);
+			return -ENOBUFS;
+		}
+	} else
+		atomic_inc(&skb->users);
+
 	cb->dump = control->dump;
 	cb->done = control->done;
 	cb->nlh = nlh;
 	cb->data = control->data;
 	cb->module = control->module;
 	cb->min_dump_alloc = control->min_dump_alloc;
-	atomic_inc(&skb->users);
 	cb->skb = skb;
 
 	sk = netlink_lookup(sock_net(ssk), ssk->sk_protocol, NETLINK_CB(skb).portid);
@@ -1850,7 +2557,8 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err)
 	if (err)
 		payload += nlmsg_len(nlh);
 
-	skb = nlmsg_new(payload, GFP_KERNEL);
+	skb = netlink_alloc_skb(in_skb->sk, nlmsg_total_size(payload),
+				NETLINK_CB(in_skb).portid, GFP_KERNEL);
 	if (!skb) {
 		struct sock *sk;
 
@@ -2116,7 +2824,7 @@ static const struct proto_ops netlink_ops = {
 	.socketpair =	sock_no_socketpair,
 	.accept =	sock_no_accept,
 	.getname =	netlink_getname,
-	.poll =		datagram_poll,
+	.poll =		netlink_poll,
 	.ioctl =	sock_no_ioctl,
 	.listen =	sock_no_listen,
 	.shutdown =	sock_no_shutdown,
@@ -2124,7 +2832,7 @@ static const struct proto_ops netlink_ops = {
 	.getsockopt =	netlink_getsockopt,
 	.sendmsg =	netlink_sendmsg,
 	.recvmsg =	netlink_recvmsg,
-	.mmap =		sock_no_mmap,
+	.mmap =		netlink_mmap,
 	.sendpage =	sock_no_sendpage,
 };