Message ID | 20121102173550.GH10877@moon |
---|---|
State | RFC, archived |
Delegated to: | David Miller |
Headers | show |
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); > . > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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);
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(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html