Merge tag 'ecryptfs-4.3-rc1-stale-dcache' of git://git.kernel.org/pub/scm/linux/kerne...

[cascardo/linux.git] / net / netlink / af_netlink.c

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index a774985..50889be 100644 (file)
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -84,6 +84,7 @@ struct listeners {
 #define NETLINK_F_BROADCAST_SEND_ERROR 0x4
 #define NETLINK_F_RECV_NO_ENOBUFS      0x8
 #define NETLINK_F_LISTEN_ALL_NSID      0x10
+#define NETLINK_F_CAP_ACK              0x20
 
 static inline int netlink_is_kernel(struct sock *sk)
 {
@@ -593,16 +594,6 @@ netlink_current_frame(const struct netlink_ring *ring,
        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;
@@ -610,11 +601,11 @@ static void netlink_increment_head(struct netlink_ring *ring)
 
 static void netlink_forward_ring(struct netlink_ring *ring)
 {
-       unsigned int head = ring->head, pos = head;
+       unsigned int head = ring->head;
        const struct nl_mmap_hdr *hdr;
 
        do {
-               hdr = __netlink_lookup_frame(ring, pos);
+               hdr = __netlink_lookup_frame(ring, ring->head);
                if (hdr->nm_status == NL_MMAP_STATUS_UNUSED)
                        break;
                if (hdr->nm_status != NL_MMAP_STATUS_SKIP)
@@ -623,6 +614,21 @@ static void netlink_forward_ring(struct netlink_ring *ring)
        } while (ring->head != head);
 }
 
+static bool netlink_has_valid_frame(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_VALID)
+                       return true;
+               pos = pos != 0 ? pos - 1 : ring->frame_max;
+       } while (pos != head);
+
+       return false;
+}
+
 static bool netlink_dump_space(struct netlink_sock *nlk)
 {
        struct netlink_ring *ring = &nlk->rx_ring;
@@ -670,8 +676,7 @@ static unsigned int netlink_poll(struct file *file, struct socket *sock,
 
        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))
+               if (netlink_has_valid_frame(&nlk->rx_ring))
                        mask |= POLLIN | POLLRDNORM;
        }
        spin_unlock_bh(&sk->sk_receive_queue.lock);
@@ -2258,6 +2263,13 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname,
                        nlk->flags &= ~NETLINK_F_LISTEN_ALL_NSID;
                err = 0;
                break;
+       case NETLINK_CAP_ACK:
+               if (val)
+                       nlk->flags |= NETLINK_F_CAP_ACK;
+               else
+                       nlk->flags &= ~NETLINK_F_CAP_ACK;
+               err = 0;
+               break;
        default:
                err = -ENOPROTOOPT;
        }
@@ -2332,6 +2344,16 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname,
                netlink_table_ungrab();
                break;
        }
+       case NETLINK_CAP_ACK:
+               if (len < sizeof(int))
+                       return -EINVAL;
+               len = sizeof(int);
+               val = nlk->flags & NETLINK_F_CAP_ACK ? 1 : 0;
+               if (put_user(len, optlen) ||
+                   put_user(val, optval))
+                       return -EFAULT;
+               err = 0;
+               break;
        default:
                err = -ENOPROTOOPT;
        }
@@ -2873,9 +2895,12 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err)
        struct nlmsghdr *rep;
        struct nlmsgerr *errmsg;
        size_t payload = sizeof(*errmsg);
+       struct netlink_sock *nlk = nlk_sk(NETLINK_CB(in_skb).sk);
 
-       /* error messages get the original request appened */
-       if (err)
+       /* Error messages get the original request appened, unless the user
+        * requests to cap the error message.
+        */
+       if (!(nlk->flags & NETLINK_F_CAP_ACK) && err)
                payload += nlmsg_len(nlh);
 
        skb = netlink_alloc_skb(in_skb->sk, nlmsg_total_size(payload),
@@ -2898,7 +2923,7 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err)
                          NLMSG_ERROR, payload, 0);
        errmsg = nlmsg_data(rep);
        errmsg->error = err;
-       memcpy(&errmsg->msg, nlh, err ? nlh->nlmsg_len : sizeof(*nlh));
+       memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg) ? nlh->nlmsg_len : sizeof(*nlh));
        netlink_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).portid, MSG_DONTWAIT);
 }
 EXPORT_SYMBOL(netlink_ack);