genl: Fix genl dumpit() locking.
Pravin B Shelar [Fri, 23 Aug 2013 19:44:55 +0000 (12:44 -0700)]
[ Upstream commit 9b96309c5b0b9e466773c07a5bc8b7b68fcf010a ]

In case of genl-family with parallel ops off, dumpif() callback
is expected to run under genl_lock, But commit def3117493eafd9df
(genl: Allow concurrent genl callbacks.) changed this behaviour
where only first dumpit() op was called under genl-lock.
For subsequent dump, only nlk->cb_lock was taken.
Following patch fixes it by defining locked dumpit() and done()
callback which takes care of genl-locking.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
CC: Jesse Gross <jesse@nicira.com>
CC: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

net/netlink/genetlink.c

index 1076fe1..8ee0b45 100644 (file)
@@ -544,6 +544,30 @@ void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 }
 EXPORT_SYMBOL(genlmsg_put);
 
+static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
+{
+       struct genl_ops *ops = cb->data;
+       int rc;
+
+       genl_lock();
+       rc = ops->dumpit(skb, cb);
+       genl_unlock();
+       return rc;
+}
+
+static int genl_lock_done(struct netlink_callback *cb)
+{
+       struct genl_ops *ops = cb->data;
+       int rc = 0;
+
+       if (ops->done) {
+               genl_lock();
+               rc = ops->done(cb);
+               genl_unlock();
+       }
+       return rc;
+}
+
 static int genl_family_rcv_msg(struct genl_family *family,
                               struct sk_buff *skb,
                               struct nlmsghdr *nlh)
@@ -572,15 +596,32 @@ static int genl_family_rcv_msg(struct genl_family *family,
                return -EPERM;
 
        if (nlh->nlmsg_flags & NLM_F_DUMP) {
-               struct netlink_dump_control c = {
-                       .dump = ops->dumpit,
-                       .done = ops->done,
-               };
+               int rc;
 
                if (ops->dumpit == NULL)
                        return -EOPNOTSUPP;
 
-               return netlink_dump_start(net->genl_sock, skb, nlh, &c);
+               if (!family->parallel_ops) {
+                       struct netlink_dump_control c = {
+                               .data = ops,
+                               .dump = genl_lock_dumpit,
+                               .done = genl_lock_done,
+                       };
+
+                       genl_unlock();
+                       rc = netlink_dump_start(net->genl_sock, skb, nlh, &c);
+                       genl_lock();
+
+               } else {
+                       struct netlink_dump_control c = {
+                               .dump = ops->dumpit,
+                               .done = ops->done,
+                       };
+
+                       rc = netlink_dump_start(net->genl_sock, skb, nlh, &c);
+               }
+
+               return rc;
        }
 
        if (ops->doit == NULL)