Commit 9652e931 authored by Patrick McHardy's avatar Patrick McHardy Committed by David S. Miller

netlink: add mmap'ed netlink helper functions

Add helper functions for looking up mmap'ed frame headers, reading and
writing their status, allocating skbs with mmap'ed data areas and a poll
function.
Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ccdfcc39
......@@ -15,10 +15,17 @@ 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 mmaped */
NETLINK_SKB_TX = 0x2, /* Packet was sent by userspace */
NETLINK_SKB_DELIVERED = 0x4, /* Packet was delivered */
};
struct netlink_skb_parms {
struct scm_creds creds; /* Skb credentials */
__u32 portid;
__u32 dst_group;
__u32 flags;
struct sock *sk;
};
......
......@@ -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>
......@@ -89,6 +90,7 @@ 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);
DEFINE_RWLOCK(nl_table_lock);
EXPORT_SYMBOL_GPL(nl_table_lock);
......@@ -109,6 +111,11 @@ static inline struct hlist_head *nl_portid_hashfn(struct nl_portid_hash *hash, u
}
#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))
......@@ -332,8 +339,154 @@ static int netlink_mmap(struct file *file, struct socket *sock,
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);
}
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;
}
#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_destroy_callback(struct netlink_callback *cb)
......@@ -350,7 +503,35 @@ static void netlink_consume_callback(struct netlink_callback *cb)
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)
......@@ -2349,7 +2530,7 @@ 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,
......
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