Re: [PATCH] firewall: Accept traffic on loopback interface if source and destination are within 127.0.0.0/8 only

[Matthias Fischer <matthias.fischer@ipfire.org>]

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Hi,

yes - sorry, forgot to mention this. Didn't want to make too much noise...

Next time I'll write if "merged or not". ;-)

Matthias

On 19.05.2020 10:21, Michael Tremer wrote:
> Hi,
> 
> False alarm. Turns out this isn’t merged, yet.
> 
> Best,
> -Michael
> 
>> On 19 May 2020, at 09:20, Michael Tremer <michael.tremer(a)ipfire.org> wrote:
>> 
>> Okay, thanks for testing this.
>> 
>> I will ask Arne to revert it.
>> 
>> -Michael
>> 
>>> On 18 May 2020, at 22:03, Matthias Fischer <matthias.fischer(a)ipfire.org> wrote:
>>> 
>>> Hi,
>>> 
>>> perhaps its only me, but after applying this patch for testing purposes
>>> I don't see any (redirected) urlfilter block pages anymore.
>>> 
>>> Only the firewall logs are telling me:
>>> 
>>> ...
>>> REJECT_INPUT lo TCP 192.168.100.254 53464 192.168.100.254 81
>>> ...
>>> 
>>> I had to build a new "Incoming Firewall Access" rule (INPUTFW) allowing
>>> TCP traffic from (e.g.) 192.168.100.254/32 to GREEN (192.168.100.254) to
>>> TCP port 81 to see a block page again...
>>> 
>>> Only me?
>>> 
>>> Best,
>>> Matthias
>>> 
>>> On 14.05.2020 12:36, Michael Tremer wrote:
>>>> Hello,
>>>> 
>>>> This is indeed *very* unlikely, but I am okay with this patch being accepted.
>>>> 
>>>> Acked-by: Michael Tremer <michael.tremer(a)ipfire.org>
>>>> 
>>>> Best,
>>>> -Michael
>>>> 
>>>>> On 13 May 2020, at 21:21, Peter Müller <peter.mueller(a)ipfire.org> wrote:
>>>>> 
>>>>> This ensures traffic on the loopback interface matches the IPv4
>>>>> loopback characteristics (source and destination are within 127.0.0.0/8)
>>>>> and prevents any damage in the unlikely case of non-loopback traffic
>>>>> being injected/emitted (in)to the loopback interface.
>>>>> 
>>>>> Cc: Arne Fitzenreiter <arne.fitzenreiter(a)ipfire.org>
>>>>> Cc: Michael Tremer <michael.tremer(a)ipfire.org>
>>>>> Signed-off-by: Peter Müller <peter.mueller(a)ipfire.org>
>>>>> ---
>>>>> src/initscripts/system/firewall | 6 +++---
>>>>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>>>> 
>>>>> diff --git a/src/initscripts/system/firewall b/src/initscripts/system/firewall
>>>>> index 00512d9fa..409aaf7a9 100644
>>>>> --- a/src/initscripts/system/firewall
>>>>> +++ b/src/initscripts/system/firewall
>>>>> @@ -219,10 +219,10 @@ iptables_init() {
>>>>> 	iptables -A INPUT -j ICMPINPUT
>>>>> 	iptables -A ICMPINPUT -p icmp --icmp-type 8 -j ACCEPT
>>>>> 
>>>>> -	# Accept everything on loopback
>>>>> +	# Accept everything on loopback if both source and destination are within 127.0.0.0/8
>>>>> 	iptables -N LOOPBACK
>>>>> -	iptables -A LOOPBACK -i lo -j ACCEPT
>>>>> -	iptables -A LOOPBACK -o lo -j ACCEPT
>>>>> +	iptables -A LOOPBACK -i lo -s 127.0.0.0/8 -d 127.0.0.0/8 -j ACCEPT
>>>>> +	iptables -A LOOPBACK -o lo -s 127.0.0.0/8 -d 127.0.0.0/8 -j ACCEPT
>>>>> 
>>>>> 	# Filter all packets with loopback addresses on non-loopback interfaces.
>>>>> 	iptables -A LOOPBACK -s 127.0.0.0/8 -j DROP
>>>>> -- 
>>>>> 2.26.1
>>>> 
>>> 
>> 
>