unix_diag: Dumping exact socket core

The socket inode is used as a key for lookup. This is effectively
the only really unique ID of a unix socket, but using this for
search currently has one problem -- it is O(number of sockets) :(

Does it worth fixing this lookup or inventing some other ID for
unix sockets?

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/unix/diag.c b/net/unix/diag.c
index 86d85abf90c68c23c6808415f6e9dc3ddbcb46c4..d7bd48c49ee559d5073369e28c0025ac4b747155 100644 (file)
--- a/net/unix/diag.c
+++ b/net/unix/diag.c
@@ -89,11 +89,76 @@ done:
        return skb->len;
 }
 
+static struct sock *unix_lookup_by_ino(int ino)
+{
+       int i;
+       struct sock *sk;
+
+       spin_lock(&unix_table_lock);
+       for (i = 0; i <= UNIX_HASH_SIZE; i++) {
+               struct hlist_node *node;
+
+               sk_for_each(sk, node, &unix_socket_table[i])
+                       if (ino == sock_i_ino(sk)) {
+                               sock_hold(sk);
+                               spin_unlock(&unix_table_lock);
+
+                               return sk;
+                       }
+       }
+
+       spin_unlock(&unix_table_lock);
+       return NULL;
+}
+
 static int unix_diag_get_exact(struct sk_buff *in_skb,
                               const struct nlmsghdr *nlh,
                               struct unix_diag_req *req)
 {
-       return -EAFNOSUPPORT;
+       int err = -EINVAL;
+       struct sock *sk;
+       struct sk_buff *rep;
+       unsigned int extra_len;
+
+       if (req->udiag_ino == 0)
+               goto out_nosk;
+
+       sk = unix_lookup_by_ino(req->udiag_ino);
+       err = -ENOENT;
+       if (sk == NULL)
+               goto out_nosk;
+
+       err = sock_diag_check_cookie(sk, req->udiag_cookie);
+       if (err)
+               goto out;
+
+       extra_len = 256;
+again:
+       err = -ENOMEM;
+       rep = alloc_skb(NLMSG_SPACE((sizeof(struct unix_diag_msg) + extra_len)),
+                       GFP_KERNEL);
+       if (!rep)
+               goto out;
+
+       err = sk_diag_fill(sk, rep, req, NETLINK_CB(in_skb).pid,
+                          nlh->nlmsg_seq, 0, req->udiag_ino);
+       if (err < 0) {
+               kfree_skb(rep);
+               extra_len += 256;
+               if (extra_len >= PAGE_SIZE)
+                       goto out;
+
+               goto again;
+       }
+       err = netlink_unicast(sock_diag_nlsk, rep, NETLINK_CB(in_skb).pid,
+                             MSG_DONTWAIT);
+       if (err > 0)
+               err = 0;
+out:
+       if (sk)
+               sock_put(sk);
+out_nosk:
+       return err;
 }
 
 static int unix_diag_handler_dump(struct sk_buff *skb, struct nlmsghdr *h)