Re[2]: [PATCH 2/2] IPVS: make failure of netns init more stable

Hello 
>
>Hello,
>
>On Tue, 17 Apr 2012, Hans Schillstrom wrote:
>
>> I wonder if we are chasing ghosts...
>> 
>> With proper fault handling I can't even see a case when it (net->ipvs) can be used.
>> Can you see a case when it could happen?
>> Still we can set it to NULL on error exit and cleanup as you suggested, that doesn't harm I think.
>> 
>> A. If you add a netns and it fails the entire ns will be rolled back, 
>>    and no access to that ns can occur.
>>    That ns does not exist
>
>	Agreed
>
>> B. If you insert ip_vs.ko when having one or more name spaces and 
>>    __ip_vs_init() returns an error the module will be unloaded.
>>    All ready loaded ns will not be affected.
>
>	Yes, ip_vs_init fails.
>
>> C. insmod of ex. ip_vs_ftp only affects loaded name spaces
>>    and if the load of ip_vs_ftp fails it will be unloaded without affecting ip_vs(.ko)
>>    (If ip_vs.ko is not loaded then it has to be loaded first case B...)
>> 
>> With a "compiled in" ip_vs case B doesn't exist.
>
>	It is this case that can happen, we can only guess how
>difficult is to get ENOMEM here. IIRC, we can generate only
>ENOMEM error on IPVS core load.
>
>	I assume Simon has such setup and changes code to
>trigger load error. When I generate ENOMEM on IPVS core init
>for such case I get ENOENT from register_ip_vs_app when
>patch 1 and 2 for apps are applied, i.e. net->ipvs is NULL.
>You can check it with NF_CONNTRACK=y, IP_VS=y and
>IP_VS_FTP=m. You only need to trigger ENOMEM in __ip_vs_init.


I did test this with 4 netns loaded and modprobe ip_vs_ftp
In the 4:th netns  (ipvs->gen >= 4) fire a -ENOMEM 
The result was as expected, ip_vs_ftp was not loaded.

All patches below was loaded. (included the ipvs NULL check)

Just for "fun" I also added a printk in the ipvs NULL check
but I can't trigger it. 

Simon:
 do you have any possibility to test it or give me a hint how to do ?
(Just to make sure that the patches below will be sufficient)

>
>> With proper fault handling i.e. all ways returning fault codes to the netns init,
>> there is no need for checking for  "if (!net->ipvs)" or any other action.
>
>	Probably but one check on load does not hurt much.

I think I have tested all of above now and my conclusion is that we need the following patches
which also was applied when the tests was run.
(with a small reservation that I might have missed some..)

[PATCH v3 1/2] netfilter: ipvs: Verify that IP_VS protocol has been registered, Sasha Levin
[PATCH v3 2/2] netfilter: ipvs: use GFP_KERNEL allocation where possible, Sasha Levin

[PATCH 0/6] Convert some GFP_ATOMIC allocations, Julian Anastasov
[PATCH 1/6] ipvs: timeout tables do not need GFP_ATOMIC allocation, Julian Anastasov
[PATCH 2/6] ipvs: SH scheduler does not need GFP_ATOMIC allocation, Julian Anastasov
[PATCH 5/6] ipvs: LBLCR scheduler does not need GFP_ATOMIC allocation on init, Julian Anastasov
[PATCH 6/6] ipvs: WRR scheduler does not need GFP_ATOMIC allocation, Julian Anastasov
[PATCH 3/6] ipvs: DH scheduler does not need GFP_ATOMIC allocation, Julian Anastasov
[PATCH 4/6] ipvs: LBLC scheduler does not need GFP_ATOMIC allocation on init, Julian Anastasov

[PATCH] ipvs: fix crash in ip_vs_control_net_cleanup on unload, Julian Anastasov

[PATCH 1/2] ipvs: reset ipvs pointer in netns, Julian Anastasov
[PATCH 1/2] IPVS: take care of return value from protocol init_netns, Hans Schillstrom

To be safe,  add this to  [PATCH 1/2] ipvs: reset ipvs pointer in netns or make a new patch


>
>Regards
>
>--
>Julian Anastasov <ja@ssi.bg>

Regards
Hans Schillstrom <hans@schillstrom.com>

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Hello,

On Wed, 18 Apr 2012, Hans Schillstrom wrote:

> >trigger load error. When I generate ENOMEM on IPVS core init
> >for such case I get ENOENT from register_ip_vs_app when
> >patch 1 and 2 for apps are applied, i.e. net->ipvs is NULL.
> >You can check it with NF_CONNTRACK=y, IP_VS=y and
> >IP_VS_FTP=m. You only need to trigger ENOMEM in __ip_vs_init.
> 
> 
> I did test this with 4 netns loaded and modprobe ip_vs_ftp
> In the 4:th netns  (ipvs->gen >= 4) fire a -ENOMEM 
> The result was as expected, ip_vs_ftp was not loaded.
> 
> All patches below was loaded. (included the ipvs NULL check)
> 
> Just for "fun" I also added a printk in the ipvs NULL check
> but I can't trigger it. 

	I trigger it in this way (ip_vs in kernel, ip_vs_ftp
as module):

        if (1 || ip_vs_app_net_init(net) < 0)
                goto app_fail;

	This causes ip_vs core to fail. I use NET_NS=n.

> Simon:
>  do you have any possibility to test it or give me a hint how to do ?
> (Just to make sure that the patches below will be sufficient)
> 
> >
> >> With proper fault handling i.e. all ways returning fault codes to the netns init,
> >> there is no need for checking for  "if (!net->ipvs)" or any other action.
> >
> >	Probably but one check on load does not hurt much.
> 
> I think I have tested all of above now and my conclusion is that we need the following patches
> which also was applied when the tests was run.
> (with a small reservation that I might have missed some..)
> 
> [PATCH v3 1/2] netfilter: ipvs: Verify that IP_VS protocol has been registered, Sasha Levin
> [PATCH v3 2/2] netfilter: ipvs: use GFP_KERNEL allocation where possible, Sasha Levin
> 
> [PATCH 0/6] Convert some GFP_ATOMIC allocations, Julian Anastasov
> [PATCH 1/6] ipvs: timeout tables do not need GFP_ATOMIC allocation, Julian Anastasov
> [PATCH 2/6] ipvs: SH scheduler does not need GFP_ATOMIC allocation, Julian Anastasov
> [PATCH 5/6] ipvs: LBLCR scheduler does not need GFP_ATOMIC allocation on init, Julian Anastasov
> [PATCH 6/6] ipvs: WRR scheduler does not need GFP_ATOMIC allocation, Julian Anastasov
> [PATCH 3/6] ipvs: DH scheduler does not need GFP_ATOMIC allocation, Julian Anastasov
> [PATCH 4/6] ipvs: LBLC scheduler does not need GFP_ATOMIC allocation on init, Julian Anastasov
> 
> [PATCH] ipvs: fix crash in ip_vs_control_net_cleanup on unload, Julian Anastasov
> 
> [PATCH 1/2] ipvs: reset ipvs pointer in netns, Julian Anastasov
> [PATCH 1/2] IPVS: take care of return value from protocol init_netns, Hans Schillstrom
> 
> To be safe,  add this to  [PATCH 1/2] ipvs: reset ipvs pointer in netns or make a new patch

	The ip_vs_ftp part is fixed by:
"[PATCH 2/2] ipvs: fix app registration in netns". So, this check
for ip_vs_ftp is not needed anymore:

> diff --git a/net/netfilter/ipvs/ip_vs_ftp.c b/net/netfilter/ipvs/ip_vs_ftp.c
> index 538d74e..c757359 100644
> --- a/net/netfilter/ipvs/ip_vs_ftp.c
> +++ b/net/netfilter/ipvs/ip_vs_ftp.c
> @@ -439,6 +439,9 @@ static int __net_init __ip_vs_ftp_init(struct net *net)
>         struct ip_vs_app *app;
>         struct netns_ipvs *ipvs = net_ipvs(net);
>  
> +       if (!ipvs)
> +               return ERR_PTR(-ENOENT);
> +
>         app = kmemdup(&ip_vs_ftp, sizeof(struct ip_vs_app), GFP_KERNEL);
>         if (!app)
>                 return -ENOMEM;
> 
> diff --git a/net/netfilter/ipvs/ip_vs_lblc.c b/net/netfilter/ipvs/ip_vs_lblc.c
> index 74c7278..1d74996 100644
> --- a/net/netfilter/ipvs/ip_vs_lblc.c
> +++ b/net/netfilter/ipvs/ip_vs_lblc.c
> @@ -549,6 +549,9 @@ static int __net_init __ip_vs_lblc_init(struct net *net)
>  {
>         struct netns_ipvs *ipvs = net_ipvs(net);
>  
> +       if (!ipvs)
> +               return ERR_PTR(-ENOENT);

	You can post additional patches for lblc and lblcr but
use 'return -ENOENT;', ERR_PTR is not appropriate here, it
is for pointers.

> +
>         if (!net_eq(net, &init_net)) {
>                 ipvs->lblc_ctl_table = kmemdup(vs_vars_table,
>                                                 sizeof(vs_vars_table),
> diff --git a/net/netfilter/ipvs/ip_vs_lblcr.c b/net/netfilter/ipvs/ip_vs_lblcr.c
> index 8620c68..c328ee0 100644
> --- a/net/netfilter/ipvs/ip_vs_lblcr.c
> +++ b/net/netfilter/ipvs/ip_vs_lblcr.c
> @@ -743,6 +743,9 @@ static int __net_init __ip_vs_lblcr_init(struct net *net)
>  {
>         struct netns_ipvs *ipvs = net_ipvs(net);
>  
> +       if (!ipvs)
> +               return ERR_PTR(-ENOENT);
> +
>         if (!net_eq(net, &init_net)) {
>                 ipvs->lblcr_ctl_table = kmemdup(vs_vars_table,
>                                                 sizeof(vs_vars_table),

Regards

--
Julian Anastasov <ja@ssi.bg>
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On Wed, Apr 18, 2012 at 02:37:43PM +0200, Hans Schillstrom wrote:
> Hello 
> >
> >Hello,
> >
> >On Tue, 17 Apr 2012, Hans Schillstrom wrote:
> >
> >> I wonder if we are chasing ghosts...
> >> 
> >> With proper fault handling I can't even see a case when it (net->ipvs) can be used.
> >> Can you see a case when it could happen?
> >> Still we can set it to NULL on error exit and cleanup as you suggested, that doesn't harm I think.
> >> 
> >> A. If you add a netns and it fails the entire ns will be rolled back, 
> >>    and no access to that ns can occur.
> >>    That ns does not exist
> >
> >	Agreed
> >
> >> B. If you insert ip_vs.ko when having one or more name spaces and 
> >>    __ip_vs_init() returns an error the module will be unloaded.
> >>    All ready loaded ns will not be affected.
> >
> >	Yes, ip_vs_init fails.
> >
> >> C. insmod of ex. ip_vs_ftp only affects loaded name spaces
> >>    and if the load of ip_vs_ftp fails it will be unloaded without affecting ip_vs(.ko)
> >>    (If ip_vs.ko is not loaded then it has to be loaded first case B...)
> >> 
> >> With a "compiled in" ip_vs case B doesn't exist.
> >
> >	It is this case that can happen, we can only guess how
> >difficult is to get ENOMEM here. IIRC, we can generate only
> >ENOMEM error on IPVS core load.
> >
> >	I assume Simon has such setup and changes code to
> >trigger load error. When I generate ENOMEM on IPVS core init
> >for such case I get ENOENT from register_ip_vs_app when
> >patch 1 and 2 for apps are applied, i.e. net->ipvs is NULL.
> >You can check it with NF_CONNTRACK=y, IP_VS=y and
> >IP_VS_FTP=m. You only need to trigger ENOMEM in __ip_vs_init.
> 
> 
> I did test this with 4 netns loaded and modprobe ip_vs_ftp
> In the 4:th netns  (ipvs->gen >= 4) fire a -ENOMEM 
> The result was as expected, ip_vs_ftp was not loaded.
> 
> All patches below was loaded. (included the ipvs NULL check)
> 
> Just for "fun" I also added a printk in the ipvs NULL check
> but I can't trigger it. 
> 
> Simon:
>  do you have any possibility to test it or give me a hint how to do ?
> (Just to make sure that the patches below will be sufficient)

Hi,

Julian is correct. I made a hack to the code to force it to fail in
ip_vs_protocol_net_init() right after calling register_ip_vs_proto_netns()
for TCP.

With "netfilter: ipvs: Verify that IP_VS protocol has been registered"
applied I think that you could implement the same "test" by jumping to
cleanup after the first call to register_ip_vs_proto_netns() in the for
loop.

In my test all components of IPVS were compiled into the kernel,
no modules.
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