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Date: Mon, 16 Apr 2012 19:16:31 +0200
From: Hans Schillstrom <hans.schillstrom@...csson.com>
To: Julian Anastasov <ja@....bg>
CC: "horms@...ge.net.au" <horms@...ge.net.au>,
"wensong@...ux-vs.org" <wensong@...ux-vs.org>,
"lvs-devel@...r.kernel.org" <lvs-devel@...r.kernel.org>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"netfilter-devel@...r.kernel.org" <netfilter-devel@...r.kernel.org>,
"hans@...illstrom.com" <hans@...illstrom.com>
Subject: Re: [PATCH 2/2] IPVS: make failure of netns init more stable
Hello
On Monday 16 April 2012 16:25:23 Julian Anastasov wrote:
>
> Hello,
>
> On Mon, 16 Apr 2012, Hans Schillstrom wrote:
>
> > Add a IP_VS_F_NET_INIT_OK flag
> > that other modules can use for check of a successful init of ip_vs
> >
> > Signed-off-by: Hans Schillstrom <hans.schillstrom@...csson.com>
> > ---
>
> > diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
> > index b5a5c73..58722a2 100644
> > --- a/net/netfilter/ipvs/ip_vs_core.c
> > +++ b/net/netfilter/ipvs/ip_vs_core.c
>
> > @@ -1881,7 +1881,7 @@ static int __net_init __ip_vs_init(struct net *net)
> > return -ENOMEM;
> >
> > /* Hold the beast until a service is registerd */
> > - ipvs->enable = 0;
> > + ipvs->status = 0;
> > ipvs->net = net;
> > /* Counters used for creating unique names */
> > ipvs->gen = atomic_read(&ipvs_netns_cnt);
> > @@ -1906,6 +1906,7 @@ static int __net_init __ip_vs_init(struct net *net)
> > if (ip_vs_sync_net_init(net) < 0)
> > goto sync_fail;
> >
> > + IPVS_NETNS_OK(ipvs);
> > printk(KERN_INFO "IPVS: Creating netns size=%zu id=%d\n",
> > sizeof(struct netns_ipvs), ipvs->gen);
> > return 0;
> > @@ -1924,6 +1925,7 @@ protocol_fail:
> > control_fail:
> > ip_vs_estimator_net_cleanup(net);
> > estimator_fail:
> > + ipvs->status = 0; /* Nothing is enabled */
>
> While 1st patch looks ok, keeping net->ipvs after
> failure is not going to work. It seems you ignored the patch
> I already posted. We duplicate the pointer in net->ipvs but
> it should not be used after free.
>
Sorry, I'll revert that.
> Note that net_generic() and net->ipvs can not be
> used after ops_exit/ops_free and failed ops_init.
True, when ip_vs(.ko) fails. I missed that.
>
> But I see some inconsistency in net/core/net_namespace.c:
> __register_pernet_operations when CONFIG_NET_NS is enabled
> does not call ops_free after failed ops_init while when
> CONFIG_NET_NS is not enabled ops_free is called. The
> problem is that we leak the ops->size data allocated for the
> failed net. I think, the fix should be ops_init to free the data.
Are you sure ?
In my code it does...
static int __register_pernet_operations(struct list_head *list,
struct pernet_operations *ops)
at line 417
..
for_each_net(net) {
error = ops_init(ops, net);
if (error)
goto out_undo;
...
line 426
out_undo:
/* If I have an error cleanup all namespaces I initialized */
list_del(&ops->list);
ops_exit_list(ops, &net_exit_list);
ops_free_list(ops, &net_exit_list);
return error;
}
> The 2nd problem is that after ops_free the
> net_generic pointer remains assigned in ptr[id-1], even
> after being freed. Not sure if recent changes to net_generic()
> can deal with freed data. This BUG_ON(!ptr) can not catch
> problems if one subsys uses net_generic() for another
> subsys that can be unregistered.
>
> I'm going to test such fix for ops_init:
>
> [PATCH] netns: do not leak net_generic data on failed init
>
> ops_init should free the net_generic data on
> init failure and __register_pernet_operations should not
> call ops_free when NET_NS is not enabled.
>
> Signed-off-by: Julian Anastasov <ja@....bg>
> ---
> net/core/net_namespace.c | 33 ++++++++++++++++++---------------
> 1 files changed, 18 insertions(+), 15 deletions(-)
>
> diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
> index 0e950fd..31a5ae5 100644
> --- a/net/core/net_namespace.c
> +++ b/net/core/net_namespace.c
> @@ -83,21 +83,29 @@ assign:
>
> static int ops_init(const struct pernet_operations *ops, struct net *net)
> {
> - int err;
> + int err = -ENOMEM;
> + void *data = NULL;
> +
> if (ops->id && ops->size) {
> - void *data = kzalloc(ops->size, GFP_KERNEL);
> + data = kzalloc(ops->size, GFP_KERNEL);
> if (!data)
> - return -ENOMEM;
> + goto out;
>
> err = net_assign_generic(net, *ops->id, data);
> - if (err) {
> - kfree(data);
> - return err;
> - }
> + if (err)
> + goto cleanup;
> }
> + err = 0;
> if (ops->init)
> - return ops->init(net);
> - return 0;
> + err = ops->init(net);
> + if (!err)
> + return 0;
> +
> +cleanup:
> + kfree(data);
> +
> +out:
> + return err;
> }
>
> static void ops_free(const struct pernet_operations *ops, struct net *net)
> @@ -448,12 +456,7 @@ static void __unregister_pernet_operations(struct pernet_operations *ops)
> static int __register_pernet_operations(struct list_head *list,
> struct pernet_operations *ops)
> {
> - int err = 0;
> - err = ops_init(ops, &init_net);
> - if (err)
> - ops_free(ops, &init_net);
> - return err;
> -
> + return ops_init(ops, &init_net);
> }
>
> static void __unregister_pernet_operations(struct pernet_operations *ops)
--
Regards
Hans Schillstrom <hans.schillstrom@...csson.com>
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