From: Patrick McHardy <kaber@xxxxxxxxx>
Add helper functions for looking up memory mapped frame headers, reading and
writing their status, setting up skbs with memory mapped data areas and
cleaning up state again and a poll function.
Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
---
include/linux/netlink.h | 8 ++
net/netlink/af_netlink.c | 184 +++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 190 insertions(+), 2 deletions(-)
diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 969b95e..955adc1 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -190,10 +190,18 @@ static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb)
return (struct nlmsghdr *)skb->data;
}
+enum netlink_skb_flags {
+ NETLINK_SKB_MMAPED = 0x1, /* Packet data is mmapped */
+ NETLINK_SKB_TX = 0x2, /* Packet was sent by userspace */
+ NETLINK_SKB_DELIVERED = 0x4, /* Packet was delivered */
+};
+
struct netlink_skb_parms {
struct ucred creds; /* Skb credentials */
__u32 pid;
__u32 dst_group;
+ __u32 flags;
+ struct sock *sk; /* socket owning mmaped ring */
};
#define NETLINK_CB(skb) (*(struct netlink_skb_parms*)&((skb)->cb))
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 6d4db46..229bc03 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -56,6 +56,7 @@
#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>
@@ -158,6 +159,7 @@ static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait);
static int netlink_dump(struct sock *sk);
static void netlink_destroy_callback(struct netlink_callback *cb);
+static void netlink_skb_destructor(struct sk_buff *skb);
static DEFINE_RWLOCK(nl_table_lock);
static atomic_t nl_table_users = ATOMIC_INIT(0);
@@ -175,6 +177,11 @@ static struct hlist_head *nl_pid_hashfn(struct nl_pid_hash *hash, u32 pid)
}
#ifdef CONFIG_NETLINK_MMAP
+static bool netlink_skb_is_mmaped(const struct sk_buff *skb)
+{
+ return NETLINK_CB(skb).flags & NETLINK_SKB_MMAPED;
+}
+
static __pure struct page *pgvec_to_page(const void *addr)
{
if (is_vmalloc_addr(addr))
@@ -398,8 +405,153 @@ 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_MSG_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 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;
+
+ 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);
+}
+
+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;
+}
#else /* CONFIG_NETLINK_MMAP */
+#define netlink_skb_is_mmaped(skb) false
#define netlink_mmap sock_no_mmap
+#define netlink_poll datagram_poll
#endif /* CONFIG_NETLINK_MMAP */
static void netlink_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
@@ -412,7 +564,35 @@ static void netlink_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
static void netlink_skb_destructor(struct sk_buff *skb)
{
- sock_rfree(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_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)
@@ -2356,7 +2536,7 @@ 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,
--
1.7.4.4
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