* [RFC] net: netlink -- Allow netlink_dump to return error code if protocol handler is missed
@ 2012-11-02 17:35 Cyrill Gorcunov
2012-11-03 16:17 ` Pavel Emelyanov
0 siblings, 1 reply; 4+ messages in thread
From: Cyrill Gorcunov @ 2012-11-02 17:35 UTC (permalink / raw)
To: NETDEV; +Cc: David Miller, Eric Dumazet, Pavel Emelyanov
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 <gorcunov@openvz.org>
CC: David Miller <davem@davemloft.net>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Pavel Emelyanov <xemul@parallels.com>
---
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);
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [RFC] net: netlink -- Allow netlink_dump to return error code if protocol handler is missed
2012-11-02 17:35 [RFC] net: netlink -- Allow netlink_dump to return error code if protocol handler is missed Cyrill Gorcunov
@ 2012-11-03 16:17 ` Pavel Emelyanov
2012-11-03 16:39 ` Cyrill Gorcunov
0 siblings, 1 reply; 4+ messages in thread
From: Pavel Emelyanov @ 2012-11-03 16:17 UTC (permalink / raw)
To: Cyrill Gorcunov; +Cc: NETDEV, David Miller, Eric Dumazet
On 11/02/2012 09:35 PM, Cyrill Gorcunov wrote:
> 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 <gorcunov@openvz.org>
> CC: David Miller <davem@davemloft.net>
> CC: Eric Dumazet <eric.dumazet@gmail.com>
> CC: Pavel Emelyanov <xemul@parallels.com>
> ---
> 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;
When family-level handler is absent and sock_diag returns error this error
gets propagated back to user without this fix. Why do we need it in case
we return error from protocol-level handler?
> }
>
> nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(len), NLM_F_MULTI);
> .
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [RFC] net: netlink -- Allow netlink_dump to return error code if protocol handler is missed
2012-11-03 16:17 ` Pavel Emelyanov
@ 2012-11-03 16:39 ` Cyrill Gorcunov
2012-11-03 19:16 ` Cyrill Gorcunov
0 siblings, 1 reply; 4+ messages in thread
From: Cyrill Gorcunov @ 2012-11-03 16:39 UTC (permalink / raw)
To: Pavel Emelyanov; +Cc: NETDEV, David Miller, Eric Dumazet
On Sat, Nov 03, 2012 at 08:17:50PM +0400, Pavel Emelyanov wrote:
> > 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;
>
> When family-level handler is absent and sock_diag returns error this error
> gets propagated back to user without this fix. Why do we need it in case
> we return error from protocol-level handler?
Because as far as I can say the family-level handler already has such error
returning code in __sock_diag_rcv_msg. Or you mean something else?
Cyrill
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [RFC] net: netlink -- Allow netlink_dump to return error code if protocol handler is missed
2012-11-03 16:39 ` Cyrill Gorcunov
@ 2012-11-03 19:16 ` Cyrill Gorcunov
0 siblings, 0 replies; 4+ messages in thread
From: Cyrill Gorcunov @ 2012-11-03 19:16 UTC (permalink / raw)
To: Pavel Emelyanov; +Cc: NETDEV, David Miller, Eric Dumazet
On Sat, Nov 03, 2012 at 08:39:58PM +0400, Cyrill Gorcunov wrote:
> On Sat, Nov 03, 2012 at 08:17:50PM +0400, Pavel Emelyanov wrote:
> > > 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;
> >
> > When family-level handler is absent and sock_diag returns error this error
> > gets propagated back to user without this fix. Why do we need it in case
> > we return error from protocol-level handler?
>
> Because as far as I can say the family-level handler already has such error
> returning code in __sock_diag_rcv_msg. Or you mean something else?
OK, it seems I got what you mean, cooking/testing new patch.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2012-11-03 19:16 UTC | newest]
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2012-11-02 17:35 [RFC] net: netlink -- Allow netlink_dump to return error code if protocol handler is missed Cyrill Gorcunov
2012-11-03 16:17 ` Pavel Emelyanov
2012-11-03 16:39 ` Cyrill Gorcunov
2012-11-03 19:16 ` Cyrill Gorcunov
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