The current behaviour around NLM_F_ECHO is inconsistent
and spread all around in various subsystems and doesn't
represent what it was meant for.
This patch handles NLM_F_ECHO in netlink_rcv_skb() to
handle it in a central point. Most subsystems currently
interpret NLM_F_ECHO as to just unicast events to the
originator of the change while the real meaning of the
flag is to echo the request.
Signed-off-by: Thomas Graf <[EMAIL PROTECTED]>
Index: net-2.6.19.git/net/netlink/af_netlink.c
===================================================================
--- net-2.6.19.git.orig/net/netlink/af_netlink.c
+++ net-2.6.19.git/net/netlink/af_netlink.c
@@ -1430,6 +1430,28 @@ int netlink_dump_start(struct sock *ssk,
return 0;
}
+static void netlink_echo(struct sk_buff *in_skb, struct nlmsghdr *orig)
+{
+ struct sk_buff *skb;
+ struct nlmsghdr *nlh;
+ int payload = nlmsg_len(orig);
+
+ skb = nlmsg_new(nlmsg_total_size(payload), GFP_KERNEL);
+ if (skb == NULL)
+ return;
+
+ /*
+ * Return original header with pid set to 0 (from kernel) and
+ * NLM_F_REQUEST flag removed to indicate this is not a request
+ * for an echo but the reply.
+ */
+ nlh = __nlmsg_put(skb, 0, orig->nlmsg_seq, orig->nlmsg_type,
+ payload, orig->nlmsg_flags & ~NLM_F_REQUEST);
+ memcpy(nlmsg_data(nlh), nlmsg_data(orig), payload);
+
+ nlmsg_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).pid);
+}
+
void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err)
{
struct sk_buff *skb;
@@ -1476,6 +1498,9 @@ static int netlink_rcv_skb(struct sk_buf
if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
return 0;
+ if (nlh->nlmsg_flags & NLM_F_ECHO)
+ netlink_echo(skb, nlh);
+
if (cb(skb, nlh, &err) < 0) {
/* Not an error, but we have to interrupt processing
* here. Note: that in this case we do not pull
-
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