* [PATCH net] inet_ecn: Fix endianness of checksum update when setting ECT(1)
@ 2020-11-30 18:37 Toke Høiland-Jørgensen
2020-12-02 1:24 ` Jakub Kicinski
0 siblings, 1 reply; 3+ messages in thread
From: Toke Høiland-Jørgensen @ 2020-11-30 18:37 UTC (permalink / raw)
To: David S. Miller, Jakub Kicinski
Cc: Toke Høiland-Jørgensen, netdev, Jonathan Morton, Pete Heist
When adding support for propagating ECT(1) marking in IP headers it seems I
suffered from endianness-confusion in the checksum update calculation: In
fact the ECN field is in the *lower* bits of the first 16-bit word of the
IP header when calculating in network byte order. This means that the
addition performed to update the checksum field was wrong; let's fix that.
Fixes: b723748750ec ("tunnel: Propagate ECT(1) when decapsulating as recommended by RFC6040")
Reported-by: Jonathan Morton <chromatix99@gmail.com>
Tested-by: Pete Heist <pete@heistp.net>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
include/net/inet_ecn.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/net/inet_ecn.h b/include/net/inet_ecn.h
index e1eaf1780288..563457fec557 100644
--- a/include/net/inet_ecn.h
+++ b/include/net/inet_ecn.h
@@ -107,7 +107,7 @@ static inline int IP_ECN_set_ect1(struct iphdr *iph)
if ((iph->tos & INET_ECN_MASK) != INET_ECN_ECT_0)
return 0;
- check += (__force u16)htons(0x100);
+ check += (__force u16)htons(0x1);
iph->check = (__force __sum16)(check + (check>=0xFFFF));
iph->tos ^= INET_ECN_MASK;
--
2.29.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH net] inet_ecn: Fix endianness of checksum update when setting ECT(1)
2020-11-30 18:37 [PATCH net] inet_ecn: Fix endianness of checksum update when setting ECT(1) Toke Høiland-Jørgensen
@ 2020-12-02 1:24 ` Jakub Kicinski
2020-12-02 10:07 ` Toke Høiland-Jørgensen
0 siblings, 1 reply; 3+ messages in thread
From: Jakub Kicinski @ 2020-12-02 1:24 UTC (permalink / raw)
To: Toke Høiland-Jørgensen
Cc: David S. Miller, netdev, Jonathan Morton, Pete Heist
On Mon, 30 Nov 2020 19:37:05 +0100 Toke Høiland-Jørgensen wrote:
> When adding support for propagating ECT(1) marking in IP headers it seems I
> suffered from endianness-confusion in the checksum update calculation: In
> fact the ECN field is in the *lower* bits of the first 16-bit word of the
> IP header when calculating in network byte order. This means that the
> addition performed to update the checksum field was wrong; let's fix that.
>
> Fixes: b723748750ec ("tunnel: Propagate ECT(1) when decapsulating as recommended by RFC6040")
> Reported-by: Jonathan Morton <chromatix99@gmail.com>
> Tested-by: Pete Heist <pete@heistp.net>
> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Applied and queued, thanks!
> diff --git a/include/net/inet_ecn.h b/include/net/inet_ecn.h
> index e1eaf1780288..563457fec557 100644
> --- a/include/net/inet_ecn.h
> +++ b/include/net/inet_ecn.h
> @@ -107,7 +107,7 @@ static inline int IP_ECN_set_ect1(struct iphdr *iph)
> if ((iph->tos & INET_ECN_MASK) != INET_ECN_ECT_0)
> return 0;
>
> - check += (__force u16)htons(0x100);
> + check += (__force u16)htons(0x1);
>
> iph->check = (__force __sum16)(check + (check>=0xFFFF));
> iph->tos ^= INET_ECN_MASK;
This seems to be open coding csum16_add() - is there a reason and if
not perhaps worth following up in net-next?
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH net] inet_ecn: Fix endianness of checksum update when setting ECT(1)
2020-12-02 1:24 ` Jakub Kicinski
@ 2020-12-02 10:07 ` Toke Høiland-Jørgensen
0 siblings, 0 replies; 3+ messages in thread
From: Toke Høiland-Jørgensen @ 2020-12-02 10:07 UTC (permalink / raw)
To: Jakub Kicinski; +Cc: David S. Miller, netdev, Jonathan Morton, Pete Heist
Jakub Kicinski <kuba@kernel.org> writes:
> On Mon, 30 Nov 2020 19:37:05 +0100 Toke Høiland-Jørgensen wrote:
>> When adding support for propagating ECT(1) marking in IP headers it seems I
>> suffered from endianness-confusion in the checksum update calculation: In
>> fact the ECN field is in the *lower* bits of the first 16-bit word of the
>> IP header when calculating in network byte order. This means that the
>> addition performed to update the checksum field was wrong; let's fix that.
>>
>> Fixes: b723748750ec ("tunnel: Propagate ECT(1) when decapsulating as recommended by RFC6040")
>> Reported-by: Jonathan Morton <chromatix99@gmail.com>
>> Tested-by: Pete Heist <pete@heistp.net>
>> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
>
> Applied and queued, thanks!
>
>> diff --git a/include/net/inet_ecn.h b/include/net/inet_ecn.h
>> index e1eaf1780288..563457fec557 100644
>> --- a/include/net/inet_ecn.h
>> +++ b/include/net/inet_ecn.h
>> @@ -107,7 +107,7 @@ static inline int IP_ECN_set_ect1(struct iphdr *iph)
>> if ((iph->tos & INET_ECN_MASK) != INET_ECN_ECT_0)
>> return 0;
>>
>> - check += (__force u16)htons(0x100);
>> + check += (__force u16)htons(0x1);
>>
>> iph->check = (__force __sum16)(check + (check>=0xFFFF));
>> iph->tos ^= INET_ECN_MASK;
>
> This seems to be open coding csum16_add() - is there a reason and if
> not perhaps worth following up in net-next?
Hmm, good point. I think I originally just copied this from
IP_ECN_set_ce(), which comes all the way back from the initial
Linux-2.6.12-rc2 commit in git. So I suppose it may just predate the
csum helpers? I'll wait for this patch to get propagated to net-next,
then follow up with a fix there :)
-Toke
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-11-30 18:37 [PATCH net] inet_ecn: Fix endianness of checksum update when setting ECT(1) Toke Høiland-Jørgensen
2020-12-02 1:24 ` Jakub Kicinski
2020-12-02 10:07 ` Toke Høiland-Jørgensen
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