[CRIU] [PATCH 1/2] net/sysctl: fix ipv4 forwarding

[Pavel Tikhomirov]

On 06/10/2016 06:08 PM, Pavel Emelyanov wrote:
> On 06/06/2016 12:23 PM, Pavel Tikhomirov wrote:
>> Restore all/accept_redirects and default/forwarding after
>> all/forwarding as the last can influence the former two.
>> (see inet_forward_change in kernel)
>>
>> # sysctl -w net.ipv4.conf.all.forwarding=1
>> net.ipv4.conf.all.forwarding = 1
>> # sysctl -w net.ipv4.conf.default.forwarding=1
>> net.ipv4.conf.default.forwarding = 1
>> # sysctl -w net.ipv4.conf.all.forwarding=0
>> net.ipv4.conf.all.forwarding = 0
>> # sysctl net.ipv4.conf.default.forwarding
>> net.ipv4.conf.default.forwarding = 0
>>
>> Not to break image backward/forward compatibility just append
>> another copy of "accept_redirects" to lists
>>
>> Trigered with netns-dev test in VZ7CT with vzlinux-6-x86_64 template
>> https://jira.sw.ru/browse/PSBM-47355
>>
>> Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
>> ---
>>  criu/net.c | 10 ++++++----
>>  1 file changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/criu/net.c b/criu/net.c
>> index d57e0aa..4b30a35 100644
>> --- a/criu/net.c
>> +++ b/criu/net.c
>> @@ -108,6 +108,7 @@ static char *devconfs4[] = {
>>  	"ignore_routes_with_linkdown",
>>  	"drop_gratuitous_arp",
>>  	"drop_unicast_in_l2_multicast",
>> +	"accept_redirects",
>>  };
>>
>>  char *devconfs6[] = {
>> @@ -153,6 +154,7 @@ char *devconfs6[] = {
>>  	"use_oif_addrs_only",
>>  	"use_optimistic",
>>  	"use_tempaddr",
>> +	"accept_redirects",
>>  };
>>
>>  #define CONF_OPT_PATH "net/%s/conf/%s/%s"
>> @@ -1327,18 +1329,18 @@ static int restore_netns_conf(int pid, NetnsEntry **netns)
>>  	}
>>
>>  	if ((*netns)->def_conf4) {
>> -		ret = ipv4_conf_op("default", (*netns)->def_conf4, (*netns)->n_def_conf4, CTL_WRITE, NULL);
>> +		ret = ipv4_conf_op("all", (*netns)->all_conf4, (*netns)->n_all_conf4, CTL_WRITE, NULL);
>>  		if (ret)
>>  			goto out;
>> -		ret = ipv4_conf_op("all", (*netns)->all_conf4, (*netns)->n_all_conf4, CTL_WRITE, NULL);
>> +		ret = ipv4_conf_op("default", (*netns)->def_conf4, (*netns)->n_def_conf4, CTL_WRITE, NULL);
>
> But you also change the current all/default restore logic for everything.
> Let's better add quirks for these sysctls as you did for mtu.

I think it is better to change here for all sysctls, as: 1) it will be 
same order as in ipv6, 2) If someone makes something similar to 
"forwarding" in kernel we will be ready 3)quirk for mtu just not 
optimizes mtu restore, but here we will need to add second restore of 
default forwarding...

>
>>  		if (ret)
>>  			goto out;
>>  	} else if ((*netns)->def_conf) {
>>  		/* Backward compatibility */
>> -		ret = ipv4_conf_op_old("default", (*netns)->def_conf, (*netns)->n_def_conf, CTL_WRITE, NULL);
>> +		ret = ipv4_conf_op_old("all", (*netns)->all_conf, (*netns)->n_all_conf, CTL_WRITE, NULL);
>>  		if (ret)
>>  			goto out;
>> -		ret = ipv4_conf_op_old("all", (*netns)->all_conf, (*netns)->n_all_conf, CTL_WRITE, NULL);
>> +		ret = ipv4_conf_op_old("default", (*netns)->def_conf, (*netns)->n_def_conf, CTL_WRITE, NULL);
>>  		if (ret)
>>  			goto out;
>>  	}
>>
>

-- 
Best regards, Tikhomirov Pavel
Software Developer, Virtuozzo.