From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cyrill Gorcunov Subject: [RFC] net: netlink -- Allow netlink_dump to return error code if protocol handler is missed Date: Fri, 2 Nov 2012 21:35:50 +0400 Message-ID: <20121102173550.GH10877@moon> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Miller , Eric Dumazet , Pavel Emelyanov To: NETDEV Return-path: Received: from mail-lb0-f174.google.com ([209.85.217.174]:46391 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763227Ab2KBRgR (ORCPT ); Fri, 2 Nov 2012 13:36:17 -0400 Received: by mail-lb0-f174.google.com with SMTP id n3so2784975lbo.19 for ; Fri, 02 Nov 2012 10:36:16 -0700 (PDT) Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: We've observed that in case if UDP diag module is not supported in kernel the netlink returns NLMSG_DONE without notifying a caller that handler is missed. This patch makes netlink_dump to return error code instead. So as example it become possible to detect such situation and handle it gracefully on userspace level. Signed-off-by: Cyrill Gorcunov CC: David Miller CC: Eric Dumazet CC: Pavel Emelyanov --- net/ipv4/inet_diag.c | 5 ++++- net/netlink/af_netlink.c | 4 ++++ 2 files changed, 8 insertions(+), 1 deletion(-) Index: linux-2.6.git/net/ipv4/inet_diag.c =================================================================== --- linux-2.6.git.orig/net/ipv4/inet_diag.c +++ linux-2.6.git/net/ipv4/inet_diag.c @@ -895,13 +895,16 @@ static int __inet_diag_dump(struct sk_bu struct inet_diag_req_v2 *r, struct nlattr *bc) { const struct inet_diag_handler *handler; + int err = 0; handler = inet_diag_lock_handler(r->sdiag_protocol); if (!IS_ERR(handler)) handler->dump(skb, cb, r, bc); + else + err = PTR_ERR(handler); inet_diag_unlock_handler(handler); - return skb->len; + return err ? : skb->len; } static int inet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb) Index: linux-2.6.git/net/netlink/af_netlink.c =================================================================== --- linux-2.6.git.orig/net/netlink/af_netlink.c +++ linux-2.6.git/net/netlink/af_netlink.c @@ -1740,6 +1740,10 @@ static int netlink_dump(struct sock *sk) else __netlink_sendskb(sk, skb); return 0; + } else if (len < 0) { + err = len; + nlk->cb = NULL; + goto errout_skb; } nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(len), NLM_F_MULTI);