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unix_diag: Dumping exact socket core
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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 <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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xemul authored and davem330 committed Dec 16, 2011
1 parent 45a96b9 commit 5d3cae8
Showing 1 changed file with 66 additions and 1 deletion.
67 changes: 66 additions & 1 deletion net/unix/diag.c
Original file line number Diff line number Diff line change
Expand Up @@ -89,11 +89,76 @@ static int unix_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
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)
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