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

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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

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);
+
        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@xxxxxx>

Regards
Hans Schillstrom <hans@xxxxxxxxxxxxxxx>

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