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>

1 files changed, 66 insertions, 1 deletions

diff --git a/net/unix/diag.c b/net/unix/diag.c
index 86d85abf90c6..d7bd48c49ee5 100644
--- 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)