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Bug 1653562 - [RHEL8] iptables v1.8.1 (nf_tables): realm: could not map name to integer
Summary: [RHEL8] iptables v1.8.1 (nf_tables): realm: could not map name to integer
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: iptables
Version: 8.0
Hardware: Unspecified
OS: Linux
medium
medium
Target Milestone: rc
: 8.1
Assignee: Phil Sutter
QA Contact: Jiri Peska
URL:
Whiteboard:
Depends On: 1682316
Blocks:
TreeView+ depends on / blocked
 
Reported: 2018-11-27 06:37 UTC by yiche
Modified: 2020-11-14 10:03 UTC (History)
5 users (show)

Fixed In Version: iptables-1.8.2-10.el8
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2019-11-05 22:17:43 UTC
Type: Bug
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHEA-2019:3573 0 None None None 2019-11-05 22:17:52 UTC

Description yiche 2018-11-27 06:37:21 UTC 
Description of problem:
iptables v1.8.1 (nf_tables): realm: could not map name -0x1/0xffff to an integer value for option "--realm".

Version-Release number of selected component (if applicable):
iptables-1.8.1-2.el8.x86_64
kernel-4.18.0-40.el8.x86_64


How reproducible:
always

Steps to Reproduce:
#iptables -A INPUT -i lo -p tcp -m realm  --realm -0x1/0xffff -j DROP
iptables v1.8.1 (nf_tables): realm: could not map name -0x1/0xffff to an integer value for option "--realm".

Actual results:


Expected results:
The rule should add success.

Additional info:
Comment 1 Phil Sutter 2018-11-29 14:48:29 UTC 
Hi Yiche,

(In reply to yiche from comment #0)
> Description of problem:
> iptables v1.8.1 (nf_tables): realm: could not map name -0x1/0xffff to an
> integer value for option "--realm".
> 
> Version-Release number of selected component (if applicable):
> iptables-1.8.1-2.el8.x86_64
> kernel-4.18.0-40.el8.x86_64
> 
> 
> How reproducible:
> always
> 
> Steps to Reproduce:
> #iptables -A INPUT -i lo -p tcp -m realm  --realm -0x1/0xffff -j DROP
> iptables v1.8.1 (nf_tables): realm: could not map name -0x1/0xffff to an
> integer value for option "--realm".

Is this a typo or do you really try to match on a negative realm value? Looking at the code, this seems not to be supported.

Cheers, Phil
Comment 2 yiche 2018-11-30 02:10:29 UTC 
But this behavior is different from RHEL7:
iptables -A INPUT -i lo -p tcp -m realm  --realm -0x1/0xffff -j DROP
iptables -A INPUT -i lo -p tcp -m realm  --realm 0x1/0xffff -j DROP
# iptables -nvL
Chain INPUT (policy ACCEPT 28 packets, 1960 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 DROP       tcp  --  lo     *       0.0.0.0/0            0.0.0.0/0            realm 0xffffffff/0xffff
    0     0 DROP       tcp  --  lo     *       0.0.0.0/0            0.0.0.0/0            realm 0x1/0xffff
I think we should follow the behavior.Or give a explain in document.
Comment 3 Phil Sutter 2018-12-03 13:56:53 UTC 
Hi Yiche,

(In reply to yiche from comment #2)
> But this behavior is different from RHEL7:
> iptables -A INPUT -i lo -p tcp -m realm  --realm -0x1/0xffff -j DROP
> iptables -A INPUT -i lo -p tcp -m realm  --realm 0x1/0xffff -j DROP
> # iptables -nvL
> Chain INPUT (policy ACCEPT 28 packets, 1960 bytes)
>  pkts bytes target     prot opt in     out     source              
> destination         
>     0     0 DROP       tcp  --  lo     *       0.0.0.0/0           
> 0.0.0.0/0            realm 0xffffffff/0xffff
>     0     0 DROP       tcp  --  lo     *       0.0.0.0/0           
> 0.0.0.0/0            realm 0x1/0xffff
> I think we should follow the behavior.Or give a explain in document.

It is actually a bug in older iptables shipped with RHEL7, the value should not be accepted. Recent iptables rejects the negative value both in legacy and nft variant, so this is intended behaviour.

I sent an enhancement to realm match documentation upstream:

https://marc.info/?l=netfilter-devel&m=154384516505389&w=2
Comment 4 Phil Sutter 2018-12-06 17:21:39 UTC 
Upstream commit to backport:

commit 290d76b443bf24999d9caacb3fdd027d6e7112a1
Author: Phil Sutter <phil>
Date:   Mon Dec 3 14:52:28 2018 +0100

    extensions: libipt_realm: Document allowed realm values
    
    Older versions of iptables allowed for negative realm values by accident
    (they would be cast to unsigned). While this was clearly a bug, document
    the fixed behaviour.
    
    Signed-off-by: Phil Sutter <phil>
    Signed-off-by: Pablo Neira Ayuso <pablo>
Comment 5 yiche 2018-12-07 03:01:23 UTC 
I file a new bug for RHEL7: Bug 1657075
Comment 6 Phil Sutter 2018-12-12 12:33:58 UTC 
Hi Yiche,

(In reply to yiche from comment #5)
> I file a new bug for RHEL7: Bug 1657075

Thanks for that!
Comment 8 Phil Sutter 2019-01-24 10:53:27 UTC 
Merely a documentation issue, therefore moving to 8.1.
Comment 12 errata-xmlrpc 2019-11-05 22:17:43 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHEA-2019:3573
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