two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Aldo Maggi]

just as matter of information, two other cases similar to mine were
reported in ubuntu bug pages:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/272896
https://bugs.launchpad.net/ubuntu/+bug/285430
i originated the first one and gave Jarek's first solution:
tcp_sack=0
which worked for the two other users.

maybe they could be contacted in order to perform further tests in a
different environment.

aldo  

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Jarek Poplawski]

On Tue, Oct 21, 2008 at 09:00:02AM +0200, Aldo Maggi wrote:
> just as matter of information, two other cases similar to mine were
> reported in ubuntu bug pages:
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/272896
> https://bugs.launchpad.net/ubuntu/+bug/285430
> i originated the first one and gave Jarek's first solution:

Hmm... let's say you gave my 50% of our first solution...

Jarek P.

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Aldo Maggi]

Il giorno Tue, 21 Oct 2008 07:20:16 +0000
Jarek Poplawski <jarkao2@gmail.com> ha scritto:

> On Tue, Oct 21, 2008 at 09:00:02AM +0200, Aldo Maggi wrote:
> > just as matter of information, two other cases similar to mine were
> > reported in ubuntu bug pages:
> > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/272896
> > https://bugs.launchpad.net/ubuntu/+bug/285430
> > i originated the first one and gave Jarek's first solution:
> 
> Hmm... let's say you gave my 50% of our first solution...
> 
> Jarek P.

ehi jarek! do not be so modest! :-D
i've acted just like a bot! :-D
i didn't have even a clue of the problem! if i gave you ssh access to my
lan you would have had the possibility to settle the matter with no my
intervention at all!

good day to you all! :-)
aldo

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Jarek Poplawski]

On Tue, Oct 21, 2008 at 09:38:27AM +0200, Aldo Maggi wrote:
> Il giorno Tue, 21 Oct 2008 07:20:16 +0000
> Jarek Poplawski <jarkao2@gmail.com> ha scritto:
> 
> > On Tue, Oct 21, 2008 at 09:00:02AM +0200, Aldo Maggi wrote:
> > > just as matter of information, two other cases similar to mine were
> > > reported in ubuntu bug pages:
> > > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/272896
> > > https://bugs.launchpad.net/ubuntu/+bug/285430
> > > i originated the first one and gave Jarek's first solution:
> > 
> > Hmm... let's say you gave my 50% of our first solution...
> > 
> > Jarek P.
> 
> ehi jarek! do not be so modest! :-D
> i've acted just like a bot! :-D
> i didn't have even a clue of the problem!

You too?...

> if i gave you ssh access to my
> lan you would have had the possibility to settle the matter with no my
> intervention at all!

Why would you want to destroy your lan?

Cheers,
Jarek P.

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Ilpo Järvinen]

Ah, I forgot to add bugzilla back last time, so added it there now.

On Tue, 21 Oct 2008, Aldo Maggi wrote:

> just as matter of information, two other cases similar to mine were
> reported in ubuntu bug pages:
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/272896
> https://bugs.launchpad.net/ubuntu/+bug/285430
> i originated the first one and gave Jarek's first solution:
> tcp_sack=0
> which worked for the two other users.
> 
> maybe they could be contacted in order to perform further tests in a
> different environment.

It's hardly surprising that I couldn't reproduce this, the non-compliance 
here is most probably in isp's device or in some end-user sold embedded 
device.

Can you try this another debug patch below (on 2.6.27.2 is fine). It moves 
the mss to the last position but should keep timestamps in place by making 
wscale as first option. It is well possible that you won't get it working 
at all except with all ts,sack and wscale set to 0 (the most likely 
result). Please try with all wscale,sack,ts combinations (no need to 
provide dumps, just working/not working per case)... This should 
tell us for quite high certaintity what is the actual option which is 
causing this (would it not be the mss-at-beginning which is the most 
likely cause), however, your finding may well be specific to your network 
while the other people might a bit different results.

In order to provide maximal compatibility, I think we just restore the 
previous ordering of the fields (basically the first patch you tested).
It has no additional cost, so it won't hurt any, but it's quite ridiculous 
still that some devices care so little about basic tcp spec which has 
devastating effect on interoperatibility here, they should really fix
the devices instead but knowing how little most of the isp & etc. care
(or even understand) I'm not expecting too much to happen on that
front, and those who care probably run some semi-sane stuff already
anyway... :-). ...Sadly, it's much easier and cheaper to blame the 
end-user's equipment or Linux (if/once it becomes known that it's in use) 
and do nothing in case one is fool enough to complain to them.


-- 
 i.


--
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index de54f02..63b0a3f 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -376,6 +376,13 @@ static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
 		*md5_hash = NULL;
 	}
 
+	if (unlikely(opts->ws)) {
+		*ptr++ = htonl((TCPOPT_NOP << 24) |
+			       (TCPOPT_WINDOW << 16) |
+			       (TCPOLEN_WINDOW << 8) |
+			       opts->ws);
+	}
+
 	if (likely(OPTION_TS & opts->options)) {
 		if (unlikely(OPTION_SACK_ADVERTISE & opts->options)) {
 			*ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
@@ -392,12 +399,6 @@ static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
 		*ptr++ = htonl(opts->tsecr);
 	}
 
-	if (unlikely(opts->mss)) {
-		*ptr++ = htonl((TCPOPT_MSS << 24) |
-			       (TCPOLEN_MSS << 16) |
-			       opts->mss);
-	}
-
 	if (unlikely(OPTION_SACK_ADVERTISE & opts->options &&
 		     !(OPTION_TS & opts->options))) {
 		*ptr++ = htonl((TCPOPT_NOP << 24) |
@@ -406,11 +407,10 @@ static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
 			       TCPOLEN_SACK_PERM);
 	}
 
-	if (unlikely(opts->ws)) {
-		*ptr++ = htonl((TCPOPT_NOP << 24) |
-			       (TCPOPT_WINDOW << 16) |
-			       (TCPOLEN_WINDOW << 8) |
-			       opts->ws);
+	if (unlikely(opts->mss)) {
+		*ptr++ = htonl((TCPOPT_MSS << 24) |
+			       (TCPOLEN_MSS << 16) |
+			       opts->mss);
 	}
 
 	if (unlikely(opts->num_sack_blocks)) {

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Jarek Poplawski]

On Tue, Oct 21, 2008 at 12:36:33PM +0300, Ilpo Järvinen wrote:
...
> Can you try this another debug patch below (on 2.6.27.2 is fine). It moves 
> the mss to the last position but should keep timestamps in place by making 
> wscale as first option. It is well possible that you won't get it working 
> at all except with all ts,sack and wscale set to 0 (the most likely 
> result). Please try with all wscale,sack,ts combinations (no need to 
> provide dumps, just working/not working per case)... This should 
> tell us for quite high certaintity what is the actual option which is 
> causing this (would it not be the mss-at-beginning which is the most 
> likely cause), [...]

I'd like to remind it seems to work with only sack off, so mss after
ts. If so, my suspicion would be around rfc's/options' dating?

Jarek P.

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Ilpo Järvinen]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 1322 bytes --]

On Tue, 21 Oct 2008, Jarek Poplawski wrote:

> On Tue, Oct 21, 2008 at 12:36:33PM +0300, Ilpo Järvinen wrote:
> ...
> > Can you try this another debug patch below (on 2.6.27.2 is fine). It moves 
> > the mss to the last position but should keep timestamps in place by making 
> > wscale as first option. It is well possible that you won't get it working 
> > at all except with all ts,sack and wscale set to 0 (the most likely 
> > result). Please try with all wscale,sack,ts combinations (no need to 
> > provide dumps, just working/not working per case)... This should 
> > tell us for quite high certaintity what is the actual option which is 
> > causing this (would it not be the mss-at-beginning which is the most 
> > likely cause), [...]
> 
> I'd like to remind it seems to work with only sack off, so mss after
> ts. If so, my suspicion would be around rfc's/options' dating?

Thanks, I missed that case... there are so many cases already... :-)
...I'm not sure we'll find some very obvious reason for this, rfc dating 
probably has very little to do here.

I still think that putting an alternative option in front is useful test 
(though my initial mss-at-beginning thought wasn't bullet-proof) but 
maybe we could skip all those alternative settings of wscale,sack,ts and 
have them just all enabled.


-- 
 i.

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Jarek Poplawski]

On Tue, Oct 21, 2008 at 01:51:10PM +0300, Ilpo Järvinen wrote:
> On Tue, 21 Oct 2008, Jarek Poplawski wrote:
> 
> > On Tue, Oct 21, 2008 at 12:36:33PM +0300, Ilpo Järvinen wrote:
> > ...
> > > Can you try this another debug patch below (on 2.6.27.2 is fine). It moves 
> > > the mss to the last position but should keep timestamps in place by making 
> > > wscale as first option. It is well possible that you won't get it working 
> > > at all except with all ts,sack and wscale set to 0 (the most likely 
> > > result). Please try with all wscale,sack,ts combinations (no need to 
> > > provide dumps, just working/not working per case)... This should 
> > > tell us for quite high certaintity what is the actual option which is 
> > > causing this (would it not be the mss-at-beginning which is the most 
> > > likely cause), [...]
> > 
> > I'd like to remind it seems to work with only sack off, so mss after
> > ts. If so, my suspicion would be around rfc's/options' dating?
> 
> Thanks, I missed that case... there are so many cases already... :-)
> ...I'm not sure we'll find some very obvious reason for this, rfc dating 
> probably has very little to do here.
> 
> I still think that putting an alternative option in front is useful test 
> (though my initial mss-at-beginning thought wasn't bullet-proof) but 
> maybe we could skip all those alternative settings of wscale,sack,ts and 
> have them just all enabled.

I agree with you, but when this test with all options enabled fails
(?!), IMHO disabling sack only could be enough to get it working
again.

Jarek P.

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Ilpo Järvinen]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 1768 bytes --]

On Tue, 21 Oct 2008, Jarek Poplawski wrote:

> On Tue, Oct 21, 2008 at 01:51:10PM +0300, Ilpo Järvinen wrote:
> > On Tue, 21 Oct 2008, Jarek Poplawski wrote:
> > 
> > > On Tue, Oct 21, 2008 at 12:36:33PM +0300, Ilpo Järvinen wrote:
> > > ...
> > > > Can you try this another debug patch below (on 2.6.27.2 is fine). It moves 
> > > > the mss to the last position but should keep timestamps in place by making 
> > > > wscale as first option. It is well possible that you won't get it working 
> > > > at all except with all ts,sack and wscale set to 0 (the most likely 
> > > > result). Please try with all wscale,sack,ts combinations (no need to 
> > > > provide dumps, just working/not working per case)... This should 
> > > > tell us for quite high certaintity what is the actual option which is 
> > > > causing this (would it not be the mss-at-beginning which is the most 
> > > > likely cause), [...]
> > > 
> > > I'd like to remind it seems to work with only sack off, so mss after
> > > ts. If so, my suspicion would be around rfc's/options' dating?
> > 
> > Thanks, I missed that case... there are so many cases already... :-)
> > ...I'm not sure we'll find some very obvious reason for this, rfc dating 
> > probably has very little to do here.
> > 
> > I still think that putting an alternative option in front is useful test 
> > (though my initial mss-at-beginning thought wasn't bullet-proof) but 
> > maybe we could skip all those alternative settings of wscale,sack,ts and 
> > have them just all enabled.
> 
> I agree with you, but when this test with all options enabled fails
> (?!), IMHO disabling sack only could be enough to get it working
> again.

...Yes it should, but we could be all wrong and it just works with them 
all too :-).


-- 
 i.

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Jarek Poplawski]

On Tue, Oct 21, 2008 at 03:18:57PM +0300, Ilpo Järvinen wrote:
...
> ...Yes it should, but we could be all wrong and it just works with them 
> all too :-).

All execept you! I guess you want it tested because you assume it's
possible? (Anyway it would be really funny :-)

Jarek P.

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Ilpo Järvinen]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 948 bytes --]

On Tue, 21 Oct 2008, Jarek Poplawski wrote:

> On Tue, Oct 21, 2008 at 03:18:57PM +0300, Ilpo Järvinen wrote:
> ...
> > ...Yes it should, but we could be all wrong and it just works with them 
> > all too :-).
> 
> All execept you! I guess you want it tested because you assume it's
> possible? (Anyway it would be really funny :-)

We're dealing with a case with in itself is really funny, yes, I assume 
it's very much possible though not too likely :-). I'd have very much 
wanted to test it myself too but sadly my network does not exhibit this 
corner-case behavior (ie., bug). Whether I'm right or wrong is not that 
significant for me :-), just understanding what the black-box does (or
is fine with) instead of just knowing how to workaround that. Or did I 
miss another case where the significance of mss specifically being there 
was decided? :-)

But whatever, if Aldo feels it's waste of his time he can just ignore 
me... :-)


-- 
 i.

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Aldo Maggi]

Il giorno Tue, 21 Oct 2008 17:16:43 +0300 (EEST)
"Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi> ha scritto:

[...]

> 
> But whatever, if Aldo feels it's waste of his time he can just ignore 
> me... :-)
> 
> 

ARE YOU JOKIIIIING? :-)
i'm only too honoured to cooperate from my very low level with you!

you do not imagine how much i value your commitment for linux!
my only dream is to see bloody ms in the dust ... and linux as a winner!

many thanks for your and your collegues work!
aldo
 

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Jarek Poplawski]

On Tue, Oct 21, 2008 at 05:16:43PM +0300, Ilpo Järvinen wrote:
...
> We're dealing with a case with in itself is really funny, yes, I assume 
> it's very much possible though not too likely :-). I'd have very much 
> wanted to test it myself too but sadly my network does not exhibit this 
> corner-case behavior (ie., bug). Whether I'm right or wrong is not that 
> significant for me :-), just understanding what the black-box does (or
> is fine with) instead of just knowing how to workaround that. Or did I 
> miss another case where the significance of mss specifically being there 
> was decided? :-)
> 
> But whatever, if Aldo feels it's waste of his time he can just ignore 
> me... :-)

Hmm... If by any chance my previous messages caused you think like
this, I'm really sorry. I completely agree with the way you deal with
this, and I don't pretend I know the result. I still agree there seems
to be not much logic in this, so all results are probable, and worth
checking - especially when we have such helpful assistant as Aldo.

Thanks,
Jarek P.

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Aldo Maggi]

[-- Attachment #1: Type: text/plain, Size: 1180 bytes --]

Il giorno Tue, 21 Oct 2008 12:36:33 +0300 (EEST)
"Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi> ha scritto:

[...]

> 
> Can you try this another debug patch below (on 2.6.27.2 is fine). It
> moves the mss to the last position but should keep timestamps in
> place by making wscale as first option. It is well possible that you
> won't get it working at all except with all ts,sack and wscale set to
> 0 (the most likely result). Please try with all wscale,sack,ts
> combinations (no need to provide dumps, just working/not working per
> case)... This should tell us for quite high certaintity what is the
> actual option which is causing this (would it not be the
> mss-at-beginning which is the most likely cause), however, your
> finding may well be specific to your network while the other people
> might a bit different results.

i've compiled 2.6.27.2 source after having patched it with your today's
patch.

it works! i.e. i can navigate (w3m kernel.org) and update (apt-get
update)

i send you anyway the usual tcpdump as in previous msgs, should it be
of any help.

do you want me to provide some more commands output?

waiting...

aldo



[-- Attachment #2: tcpdump_2-6-27-2-ilpo-2110-patch --]
[-- Type: application/octet-stream, Size: 1454 bytes --]

20:14:15.771710 IP 192.168.254.1.41264 > 204.152.191.5.80: S 2671126883:2671126883(0) win 5840 <nop,wscale 6,sackOK,timestamp 34138 0,mss 1460>
	0x0000:  00a0 c543 5feb 0010 5ac5 681c 0800 4500  ...C_...Z.h...E.
	0x0010:  003c ac39 4000 3f06 453a c0a8 fe01 cc98  .<.9@.?.E:......
	0x0020:  bf05 a130 0050 9f36 2963 0000 0000 a002  ...0.P.6)c......
	0x0030:  16d0 f773 0000 0103 0306 0402 080a 0000  ...s............
	0x0040:  855a 0000 0000 0204 05b4                 .Z........
20:14:15.992523 IP 192.168.254.1.41264 > 204.152.191.5.80: . ack 4239991373 win 92 <nop,nop,timestamp 34193 1103211035>
	0x0000:  00a0 c543 5feb 0010 5ac5 681c 0800 4500  ...C_...Z.h...E.
	0x0010:  0034 ac3a 4000 3f06 4541 c0a8 fe01 cc98  .4.:@.?.EA......
	0x0020:  bf05 a130 0050 9f36 2964 fcb9 224d 8010  ...0.P.6)d.."M..
	0x0030:  005c 3188 0000 0101 080a 0000 8591 41c1  .\1...........A.
	0x0040:  aa1b                                     ..
20:14:15.992787 IP 192.168.254.1.41264 > 204.152.191.5.80: P 0:240(240) ack 1 win 92 <nop,nop,timestamp 34193 1103211035>
	0x0000:  00a0 c543 5feb 0010 5ac5 681c 0800 4500  ...C_...Z.h...E.
	0x0010:  0124 ac3b 4000 3f06 4450 c0a8 fe01 cc98  .$.;@.?.DP......
	0x0020:  bf05 a130 0050 9f36 2964 fcb9 224d 8018  ...0.P.6)d.."M..
	0x0030:  005c 376a 0000 0101 080a 0000 8591 41c1  .\7j..........A.
	0x0040:  aa1b 4745 5420 2f20 4854 5450 2f31 2e30  ..GET./.HTTP/1.0
	0x0050:  0d0a 5573 6572 2d41 6765 6e74 3a20 7733  ..User-Agent:.w3

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Jarek Poplawski]

On Tue, Oct 21, 2008 at 08:18:57PM +0200, Aldo Maggi wrote:
...
> i've compiled 2.6.27.2 source after having patched it with your today's
> patch.
> 
> it works! i.e. i can navigate (w3m kernel.org) and update (apt-get
> update)

Ilpo, I should say you're incredible! ...But, since I've promised to
myself not to disturb you anymore (again), I can't do this, sorry :-(

Jarek P.

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[David Miller]

From: Jarek Poplawski <jarkao2@gmail.com>
Date: Tue, 21 Oct 2008 20:45:39 +0200

> On Tue, Oct 21, 2008 at 08:18:57PM +0200, Aldo Maggi wrote:
> ...
> > i've compiled 2.6.27.2 source after having patched it with your today's
> > patch.
> > 
> > it works! i.e. i can navigate (w3m kernel.org) and update (apt-get
> > update)
> 
> Ilpo, I should say you're incredible! ...But, since I've promised to
> myself not to disturb you anymore (again), I can't do this, sorry :-(

Indeed, excellent work Ilpo.

Ilpo, now that we know this fixes things for sure, could you submit
this formally with a proper signoff?

I'll queue it up for -stable too.

Thanks!

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Ilpo Järvinen]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 4369 bytes --]

On Tue, 21 Oct 2008, David Miller wrote:

> From: Jarek Poplawski <jarkao2@gmail.com>
> Date: Tue, 21 Oct 2008 20:45:39 +0200
> 
> > On Tue, Oct 21, 2008 at 08:18:57PM +0200, Aldo Maggi wrote:
> > ...
> > > i've compiled 2.6.27.2 source after having patched it with your today's
> > > patch.
> > > 
> > > it works! i.e. i can navigate (w3m kernel.org) and update (apt-get
> > > update)
> > 
> > Ilpo, I should say you're incredible! ...But, since I've promised to
> > myself not to disturb you anymore (again), I can't do this, sorry :-(
> 
> Indeed, excellent work Ilpo.
> 
> Ilpo, now that we know this fixes things for sure, could you submit
> this formally with a proper signoff?
> 
> I'll queue it up for -stable too.
> 
> Thanks!

Sure, here below is one with a warning (it's the first patch + comment).

Olon, can you please check this as well if it affect to your case too 
(though the symptoms were not that clear in your case).

It would be nice for Aldo to check what the result will be with my second 
patch (only) using sack=1,ts=0,wscale=0. I guess it does but it's a bit 
unclear if nop's in front help or not (having the patch below should 
anyway help also in that case as the mss option gets moved before it 
anyway).

--
[PATCH] tcp: Restore ordering of TCP options for the sake of inter-operability

This is not our bug! Sadly some devices cannot cope with the change
of TCP option ordering which was a result of the recent rewrite of
the option code (not that there was some particular reason steming
from the rewrite for the reordering) though any ordering of TCP
options is perfectly legal. Thus we restore the original ordering
to allow interoperability with/through such broken devices and add
some warning about this trap. Since the reordering just happened
without any particular reason, this change shouldn't cost us
anything.

There are already couple of known failure reports (within close
proximity of the last release), so the problem might be more
wide-spread than a single device. And other reports which may
be due to the same problem though the symptoms were less obvious.
Analysis of one of the case revealed (with very high probability)
that sack capability cannot be negotiated as the first option
(SYN never got a response).

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Reported-by: Aldo Maggi <sentiniate@tiscali.it>
Tested-by: Aldo Maggi <sentiniate@tiscali.it>
---
 net/ipv4/tcp_output.c |   23 +++++++++++++++++------
 1 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index de54f02..e4c5ac9 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -362,6 +362,17 @@ struct tcp_out_options {
 	__u32 tsval, tsecr;	/* need to include OPTION_TS */
 };
 
+/* Beware: Something in the Internet is very sensitive to the ordering of
+ * TCP options, we learned this through the hard way, so be careful here.
+ * Luckily we can at least blame others for their non-compliance but from
+ * inter-operatibility perspective it seems that we're somewhat stuck with
+ * the ordering which we have been using if we want to keep working with
+ * those broken things (not that it currently hurts anybody as there isn't
+ * particular reason why the ordering would need to be changed).
+ *
+ * At least SACK_PERM as the first option is known to lead to a disaster
+ * (but it may well be that other scenarios fail similarly).
+ */
 static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
 			      const struct tcp_out_options *opts,
 			      __u8 **md5_hash) {
@@ -376,6 +387,12 @@ static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
 		*md5_hash = NULL;
 	}
 
+	if (unlikely(opts->mss)) {
+		*ptr++ = htonl((TCPOPT_MSS << 24) |
+			       (TCPOLEN_MSS << 16) |
+			       opts->mss);
+	}
+
 	if (likely(OPTION_TS & opts->options)) {
 		if (unlikely(OPTION_SACK_ADVERTISE & opts->options)) {
 			*ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
@@ -392,12 +409,6 @@ static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
 		*ptr++ = htonl(opts->tsecr);
 	}
 
-	if (unlikely(opts->mss)) {
-		*ptr++ = htonl((TCPOPT_MSS << 24) |
-			       (TCPOLEN_MSS << 16) |
-			       opts->mss);
-	}
-
 	if (unlikely(OPTION_SACK_ADVERTISE & opts->options &&
 		     !(OPTION_TS & opts->options))) {
 		*ptr++ = htonl((TCPOPT_NOP << 24) |
-- 
1.5.2.2

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Aldo Maggi]

[-- Attachment #1: Type: text/plain, Size: 1129 bytes --]

Il giorno Wed, 22 Oct 2008 13:00:01 +0300 (EEST)
"Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi> ha scritto:

[...]

> 
> It would be nice for Aldo to check what the result will be with my
> second patch (only) using sack=1,ts=0,wscale=0. I guess it does but
> it's a bit unclear if nop's in front help or not (having the patch
> below should anyway help also in that case as the mss option gets
> moved before it anyway).

in order to avoid misunderstandings, i list herebelow my actions:

i've used on paperino the kernel 2.6.27.2 patched with ilpo's
21.10.2008 patch (see please comment 47 in
http://bugzilla.kernel.org/show_bug.cgi?id=11721, and NOT with the patch
contained in comment 58, right?)
i've modified the following files:
echo 0 > /proc/sys/net/ipv4/tcp_window_scaling
echo 0 > /proc/sys/net/ipv4/tcp_timestamps
echo 1 > /proc/sys/net/ipv4/tcp_sack

the results are that i CAN navigate (w3m kernel.org) and update my
system (apt-get update in debian).

should it be of any help to ilpo, i attach the usual tcpdump on the wan
eth of topolino (my home server/gw)

ciao!
aldo



[...]

[-- Attachment #2: 2210-tcpdump_2-6-27-2-ilpo-2110-patch --]
[-- Type: application/octet-stream, Size: 1233 bytes --]

13:33:40.892753 IP 192.168.254.1.44529 > 204.152.191.5.80: S 2225948920:2225948920(0) win 5840 <nop,nop,sackOK,mss 1460>
	0x0000:  00a0 c543 5feb 0010 5ac5 681c 0800 4500  ...C_...Z.h...E.
	0x0010:  0030 8fac 4000 3f06 61d3 c0a8 fe01 cc98  .0..@.?.a.......
	0x0020:  bf05 adf1 0050 84ad 48f8 0000 0000 7002  .....P..H.....p.
	0x0030:  16d0 a61f 0000 0101 0402 0204 05b4       ..............
13:33:41.112954 IP 192.168.254.1.44529 > 204.152.191.5.80: . ack 2927042638 win 5840
	0x0000:  00a0 c543 5feb 0010 5ac5 681c 0800 4500  ...C_...Z.h...E.
	0x0010:  0028 8fad 4000 3f06 61da c0a8 fe01 cc98  .(..@.?.a.......
	0x0020:  bf05 adf1 0050 84ad 48f9 ae77 204e 5010  .....P..H..w.NP.
	0x0030:  16d0 040e 0000                           ......
13:33:41.113227 IP 192.168.254.1.44529 > 204.152.191.5.80: P 0:240(240) ack 1 win 5840
	0x0000:  00a0 c543 5feb 0010 5ac5 681c 0800 4500  ...C_...Z.h...E.
	0x0010:  0118 8fae 4000 3f06 60e9 c0a8 fe01 cc98  ....@.?.`.......
	0x0020:  bf05 adf1 0050 84ad 48f9 ae77 204e 5018  .....P..H..w.NP.
	0x0030:  16d0 09f0 0000 4745 5420 2f20 4854 5450  ......GET./.HTTP
	0x0040:  2f31 2e30 0d0a 5573 6572 2d41 6765 6e74  /1.0..User-Agent
	0x0050:  3a20 7733 6d2f 302e 352e 320d 0a41 6363  :.w3m/0.5.2..Acc

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Ilpo Järvinen]

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On Wed, 22 Oct 2008, Aldo Maggi wrote:

> Il giorno Wed, 22 Oct 2008 13:00:01 +0300 (EEST)
> "Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi> ha scritto:
> 
> [...]
> 
> > 
> > It would be nice for Aldo to check what the result will be with my
> > second patch (only) using sack=1,ts=0,wscale=0. I guess it does but
> > it's a bit unclear if nop's in front help or not (having the patch
> > below should anyway help also in that case as the mss option gets
> > moved before it anyway).
> 
> in order to avoid misunderstandings, i list herebelow my actions:
> 
> i've used on paperino the kernel 2.6.27.2 patched with ilpo's
> 21.10.2008 patch (see please comment 47 in
> http://bugzilla.kernel.org/show_bug.cgi?id=11721, and NOT with the patch
> contained in comment 58, right?)

Yes, you understood me correctly. This was more or less for completeleness 
test only, to see if the nop's make any difference or not. You found out 
that they do which seemed the more sensible alternative anyway.

> i've modified the following files:
> echo 0 > /proc/sys/net/ipv4/tcp_window_scaling
> echo 0 > /proc/sys/net/ipv4/tcp_timestamps
> echo 1 > /proc/sys/net/ipv4/tcp_sack
> 
> the results are that i CAN navigate (w3m kernel.org) and update my
> system (apt-get update in debian).
>
> should it be of any help to ilpo, i attach the usual tcpdump on the wan
> eth of topolino (my home server/gw)

...It confirms that you made the right test. :-)

So only thing that was problem in your case is that sackOK option (or 
SACK_PERM in code notation) couldn't begin TCP options. With any other 
option as the first one, including nop, it does work. Thanks for all the 
testing you made and reporting it in the first place.

We'll put the latest patch (from comment #58) and it soon makes to 
2.6.28-rcsomething and hopefully with a semi-short delay to some
2.6.27.y, whichever y is appropriate at that time. I hope that the
ubuntu kernel people will then include that as well but it's beoynd
my control what they do.

Thanks again.

-- 
 i.

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Aldo Maggi]

Il giorno Wed, 22 Oct 2008 15:09:40 +0300 (EEST)
"Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi> ha scritto:

[...]

> So only thing that was problem in your case is that sackOK option (or 
> SACK_PERM in code notation) couldn't begin TCP options. With any
> other option as the first one, including nop, it does work. Thanks
> for all the testing you made and reporting it in the first place.

i thank you for your efforts in solving this problem!
it has been a real pleasere for me to cooperate with you!

all the best to you all

[...]
 
> Thanks again.
> 

i thank you! :-)

aldo

Re: two other cases Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[David Miller]

From: "Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi>
Date: Wed, 22 Oct 2008 13:00:01 +0300 (EEST)

> [PATCH] tcp: Restore ordering of TCP options for the sake of inter-operability
> 
> This is not our bug! Sadly some devices cannot cope with the change
> of TCP option ordering which was a result of the recent rewrite of
> the option code (not that there was some particular reason steming
> from the rewrite for the reordering) though any ordering of TCP
> options is perfectly legal. Thus we restore the original ordering
> to allow interoperability with/through such broken devices and add
> some warning about this trap. Since the reordering just happened
> without any particular reason, this change shouldn't cost us
> anything.
> 
> There are already couple of known failure reports (within close
> proximity of the last release), so the problem might be more
> wide-spread than a single device. And other reports which may
> be due to the same problem though the symptoms were less obvious.
> Analysis of one of the case revealed (with very high probability)
> that sack capability cannot be negotiated as the first option
> (SYN never got a response).
> 
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
> Reported-by: Aldo Maggi <sentiniate@tiscali.it>
> Tested-by: Aldo Maggi <sentiniate@tiscali.it>

Applied and I'll queue up for -stable, thanks!

Re: tcp_sack problem Re: [Bug 11721] after upgrade to 2.6.27 i cannot navigate

[Jarek Poplawski]

On Sat, Oct 25, 2008 at 10:15:15PM +0200, Aldo Maggi wrote:
> Il giorno Tue, 21 Oct 2008 07:49:54 +0000
> Jarek Poplawski <jarkao2@gmail.com> ha scritto:
> 
> > On Tue, Oct 21, 2008 at 09:27:21AM +0200, Aldo Maggi wrote:
> > ...
> > > as soon as i've time i'll replace the modem and run some tests.
> 
> just to let you know!
> i have changed my modem with a new one.
> the bug has disappeared with no modification of the tcp files.
> this shows that the problem was due to my old zyxel.
> 
> ciao!
> aldo
> 

Aldo, I think it's a very useful information, so I forward this to the
people.

Thanks again,
Jarek P.