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Bug 1664829

Summary: iptables-restore: -F and -Z on same table yields RULE_REPLACE error
Product: Red Hat Enterprise Linux 8 Reporter: Eric Garver <egarver>
Component: iptablesAssignee: Phil Sutter <psutter>
Status: CLOSED CURRENTRELEASE QA Contact: Robin Hack <rhack>
Severity: high Docs Contact:
Priority: high    
Version: 8.0CC: iptables-maint-list, psutter, todoleza, wchadwic
Target Milestone: rcFlags: rule-engine: mirror+
Target Release: 8.0   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: iptables-1.8.2-6.el8 Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2019-06-14 00:45:56 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Attachments:
Description Flags
reproducer none

Description Eric Garver 2019-01-09 18:09:02 UTC
Created attachment 1519544 [details]
reproducer

When using -F and -Z on the same table you get a RULE_REPLACE error. Presumably this is due to the counter zero. Separately they are fine.

# for I in `seq 20`; do sh /tmp/iptables-restore-flush-and-zero.sh || break; done                                                                                               
iptables-restore v1.8.2 (nf_tables): 
line 3: RULE_REPLACE failed (No such file or directory): rule in chain INPUT

# sed 's/-Z//' /tmp/iptables-restore-flush-and-zero.sh > /tmp/iptables-restore-flush.sh

# for I in `seq 20`; do sh /tmp/iptables-restore-flush.sh || break; done
*** no error ***

Comment 1 Eric Garver 2019-01-09 18:58:18 UTC
Oddly, I cannot reproduce this inside of a namespace. Which explains why it wasn't caught by firewalld's testsuite.

I'm bumping severity/priority, as this effectively breaks firewalld in the init namespace.

# ip netns add foobar
# ip netns exec foobar bash
# sh /tmp/iptables-restore-flush-and-zero.sh
** no error **
[root@rhel8 ~]# iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         

Chain INPUT_direct (0 references)
target     prot opt source               destination

Comment 7 Phil Sutter 2019-01-16 13:04:02 UTC
I can't reproduce the issue using upstream iptables and libnftnl on a RHEL8 machine, but I can reproduce it on my testing VM (with very recent upstream kernel) and RHEL8 iptables. Git bisect identified the following upstream commit fixed the problem:

commit 947c51c95edbbf08d6b3c105177ac5cfa238aade
Author: Phil Sutter <phil>
Date:   Thu Dec 20 16:09:12 2018 +0100

    xtables: Implement per chain rule cache
    
    Use recently introduced support for rules inside chains in libnftnl to
    introduce a rule cache per chain instead of a global one.
    
    A tricky bit is to decide if cache should be updated or not. Previously,
    the global rule cache was populated just once and then reused unless
    being flushed completely (via call to flush_rule_cache() with
    NULL-pointer table argument). Resemble this behaviour by introducing a
    boolean indicating cache status and fetch rules for all chains when
    updating the chain cache in nft_chain_list_get().
    
    Signed-off-by: Phil Sutter <phil>
    Signed-off-by: Pablo Neira Ayuso <pablo>

This commit will be backported on behalf of bug 1647925, too.