| Message ID | 20171125074418.16537-1-linus.luessing@c0d3.blue |
|---|---|
| State | Changes Requested |
| Delegated to: | Pablo Neira |
| Headers | show |
| Series | [net-next] bridge: ebtables: Avoid resetting limit rule state | expand |
Hi Linus, On Sat, Nov 25, 2017 at 08:44:18AM +0100, Linus Lüssing wrote: > So far any changes with ebtables will reset the state of limit rules, > leading to spikes in traffic. This is especially noticeable if changes > are done frequently, for instance via a daemon. > > This patch fixes this by bailing out from (re)setting if the limit > rule was initialized before. > > When sending packets every 250ms for 600s, with a > "--limit 1/sec --limit-burst 50" rule and a command like this > in the background: > > $ ebtables -N VOIDCHAIN > $ while true; do ebtables -F VOIDCHAIN; sleep 30; done > > The results are: > > Before: ~1600 packets > After: 650 packets > > Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue> > --- > net/bridge/netfilter/ebt_limit.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/net/bridge/netfilter/ebt_limit.c b/net/bridge/netfilter/ebt_limit.c > index 61a9f1be1263..f74b48633feb 100644 > --- a/net/bridge/netfilter/ebt_limit.c > +++ b/net/bridge/netfilter/ebt_limit.c > @@ -69,6 +69,10 @@ static int ebt_limit_mt_check(const struct xt_mtchk_param *par) > { > struct ebt_limit_info *info = par->matchinfo; > > + /* Do not reset state on unrelated table changes */ > + if (info->prev) > + return 0; What kernel version are you using? I suspect you don't have this applied? commit ec23189049651b16dc2ffab35a4371dc1f491aca Author: Willem de Bruijn <willemb@google.com> Date: Mon Jan 2 17:19:46 2017 -0500 xtables: extend matches and targets with .usersize -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Pablo, Thanks for your reply! On Tue, Nov 28, 2017 at 12:30:08AM +0100, Pablo Neira Ayuso wrote: > [...] > > diff --git a/net/bridge/netfilter/ebt_limit.c b/net/bridge/netfilter/ebt_limit.c > > index 61a9f1be1263..f74b48633feb 100644 > > --- a/net/bridge/netfilter/ebt_limit.c > > +++ b/net/bridge/netfilter/ebt_limit.c > > @@ -69,6 +69,10 @@ static int ebt_limit_mt_check(const struct xt_mtchk_param *par) > > { > > struct ebt_limit_info *info = par->matchinfo; > > > > + /* Do not reset state on unrelated table changes */ > > + if (info->prev) > > + return 0; > > What kernel version are you using? I suspect you don't have this > applied? I'm indeed using a 4.4.102 kernel, as LEDE is still in the process of updating to 4.14. So 4.4 with LEDE is where I got the measurement results from. > > commit ec23189049651b16dc2ffab35a4371dc1f491aca > Author: Willem de Bruijn <willemb@google.com> > Date: Mon Jan 2 17:19:46 2017 -0500 > > xtables: extend matches and targets with .usersize And so, no I do not have this patch. I looked at it now, but it does not seem to have any relation with .matchinfo, does it? I also had a quick look at a 4.15-rc1 kernel in a VM now. I still end up in ebt_limit_mt_check() with the variables being reset when editing the table somewhere. Regards, Linus -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Dec 04, 2017 at 05:53:35AM +0100, Linus Lüssing wrote: > And so, no I do not have this patch. I looked at it now, but it > does not seem to have any relation with .matchinfo, does it? Relation between .usersize and .checkentry I ment, not .usersize and .matchinfo. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Dec 04, 2017 at 06:20:06AM +0100, Linus Lüssing wrote: > On Mon, Dec 04, 2017 at 05:53:35AM +0100, Linus Lüssing wrote: > > And so, no I do not have this patch. I looked at it now, but it > > does not seem to have any relation with .matchinfo, does it? > > Relation between .usersize and .checkentry I ment, not > .usersize and .matchinfo. In your patch, info->prev comes set to a value from userspace, right? commit 324318f0248c31be8a08984146e7e4dd7cdd091d Author: Willem de Bruijn <willemb@google.com> Date: Tue May 9 16:17:37 2017 -0400 netfilter: xtables: zero padding in data_to_user Since that patch above, the data area is zero'ed before dumped to userspace, so we would get a null info->prev, hence defeating the trick your patch relies on. Am I missing anything? -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Linus, On Mon, Dec 04, 2017 at 05:53:35AM +0100, Linus Lüssing wrote: > Hi Pablo, > > Thanks for your reply! > > On Tue, Nov 28, 2017 at 12:30:08AM +0100, Pablo Neira Ayuso wrote: > > [...] > > > diff --git a/net/bridge/netfilter/ebt_limit.c b/net/bridge/netfilter/ebt_limit.c > > > index 61a9f1be1263..f74b48633feb 100644 > > > --- a/net/bridge/netfilter/ebt_limit.c > > > +++ b/net/bridge/netfilter/ebt_limit.c > > > @@ -69,6 +69,10 @@ static int ebt_limit_mt_check(const struct xt_mtchk_param *par) > > > { > > > struct ebt_limit_info *info = par->matchinfo; > > > > > > + /* Do not reset state on unrelated table changes */ > > > + if (info->prev) > > > + return 0; > > > > What kernel version are you using? I suspect you don't have this > > applied? > > I'm indeed using a 4.4.102 kernel, as LEDE is still in the process > of updating to 4.14. So 4.4 with LEDE is where I got the measurement > results from. > > > > > commit ec23189049651b16dc2ffab35a4371dc1f491aca > > Author: Willem de Bruijn <willemb@google.com> > > Date: Mon Jan 2 17:19:46 2017 -0500 > > > > xtables: extend matches and targets with .usersize > > And so, no I do not have this patch. I looked at it now, but it > does not seem to have any relation with .matchinfo, does it? > > I also had a quick look at a 4.15-rc1 kernel in a VM now. I still > end up in ebt_limit_mt_check() with the variables being reset > when editing the table somewhere. My question is if your fix would work with 4.15-rc1. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Dec 07, 2017 at 01:26:19AM +0100, Pablo Neira Ayuso wrote: > > I also had a quick look at a 4.15-rc1 kernel in a VM now. I still > > end up in ebt_limit_mt_check() with the variables being reset > > when editing the table somewhere. > > My question is if your fix would work with 4.15-rc1. You are absoluetly right, it's not working anymore since the commit you mentioned initially :-( ("xtables: extend matches and targets with .usersize"). info->prev is always 0 since exactly this commit. That means, trying tricks in ebt_limit_mt_check() is too late now, the old values are already overwritten? (or is there some commit scheme which installs the ebt_limit_info provided by ebt_limit_check() some time after its call?) Extending the usersize to include info->prev would probably be too hackish/ugly, right? -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Dec 08, 2017 at 06:46:06AM +0100, Linus Lüssing wrote: > Extending the usersize to include info->prev would probably be too > hackish/ugly, right? And wouldn't be enough anyway, since info->{credit,credit_cap,cost} would still be zeroed... Hm. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/bridge/netfilter/ebt_limit.c b/net/bridge/netfilter/ebt_limit.c index 61a9f1be1263..f74b48633feb 100644 --- a/net/bridge/netfilter/ebt_limit.c +++ b/net/bridge/netfilter/ebt_limit.c @@ -69,6 +69,10 @@ static int ebt_limit_mt_check(const struct xt_mtchk_param *par) { struct ebt_limit_info *info = par->matchinfo; + /* Do not reset state on unrelated table changes */ + if (info->prev) + return 0; + /* Check for overflow. */ if (info->burst == 0 || user2credits(info->avg * info->burst) < user2credits(info->avg)) {
So far any changes with ebtables will reset the state of limit rules, leading to spikes in traffic. This is especially noticeable if changes are done frequently, for instance via a daemon. This patch fixes this by bailing out from (re)setting if the limit rule was initialized before. When sending packets every 250ms for 600s, with a "--limit 1/sec --limit-burst 50" rule and a command like this in the background: $ ebtables -N VOIDCHAIN $ while true; do ebtables -F VOIDCHAIN; sleep 30; done The results are: Before: ~1600 packets After: 650 packets Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue> --- net/bridge/netfilter/ebt_limit.c | 4 ++++ 1 file changed, 4 insertions(+)