[Bug 1271] New: iptables-restore may double-lock when using --table

[bugzilla-daemon at netfilter.org]

https://bugzilla.netfilter.org/show_bug.cgi?id=1271

            Bug ID: 1271
           Summary: iptables-restore may double-lock when using --table
           Product: iptables
           Version: 1.6.x
          Hardware: x86_64
                OS: Fedora
            Status: NEW
          Severity: minor
          Priority: P5
         Component: iptables-restore
          Assignee: netfilter-buglog at lists.netfilter.org
          Reporter: contact+netfilter at jgoguen.ca

Created attachment 541
  --> https://bugzilla.netfilter.org/attachment.cgi?id=541&action=edit
Path to free the lock when skipping a table

Currently, when running `iptables-restore --table=X`, where `X` is not the
first
table in the rules dump, the restore will fail when parsing the second table:

- a lock is acquird when parsing the first table name
- the table name does not match the parameter to `--table` so processing
continues until the next table
- when processing the next table a lock is acquired, which fails because a lock
is already held

This will release the lock as soon as it's decided the current table won't be
used.

With existing code:

    # 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

    # iptables-restore <iptables.dump
    Another app is currently holding the xtables lock. Perhaps you want to use
the -w option?

    # 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

With the change from the attached patch:
    # 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

    # iptables-restore <iptables.dump

    # iptables -L
    Chain INPUT (policy DROP)
    target     prot opt source               destination
    ACCEPT     all  --  anywhere             anywhere
    ACCEPT     all  --  anywhere             anywhere             state
RELATED,ESTABLISHED
    ACCEPT     icmp --  anywhere             anywhere

    Chain FORWARD (policy DROP)
    target     prot opt source               destination

    Chain OUTPUT (policy ACCEPT)
    target     prot opt source               destination
    REJECT     tcp  --  anywhere             anywhere             tcp
dpt:netbios-ns reject-with icmp-port-unreachable
    REJECT     udp  --  anywhere             anywhere             udp
dpt:netbios-ns reject-with icmp-port-unreachable

And the test suite:
    # ./iptables/tests/shell/run-tests.sh

    I: [OK]          ././iptables/tests/shell/testcases/chain/0001duplicate_1
    I: [OK]          ././iptables/tests/shell/testcases/chain/0002newchain_0
    I: [OK]          ././iptables/tests/shell/testcases/chain/0003rename_1
    I: [OK]          ././iptables/tests/shell/testcases/ebtables/0001-ebtables-
basic_0
    I: [OK]          ././iptables/tests/shell/testcases/firewalld-restore/0001-
firewalld_0
    I: [OK]          ././iptables/tests/shell/testcases/firewalld-restore/0002-
firewalld-restart_0
    I: [OK]          ././iptables/tests/shell/testcases/ipt-restore/0001load-
specific-table_0
    I: [OK]          ././iptables/tests/shell/testcases/ipt-save/0001load-
dumps_0
    I: [OK]          ././iptables/tests/shell/testcases/ipt-save/0002load-
fedora27-firewalld_0
    I: legacy results: [OK] 9 [FAILED] 0 [TOTAL] 9
    I: [OK]          ././iptables/tests/shell/testcases/chain/0001duplicate_1
    I: [OK]          ././iptables/tests/shell/testcases/chain/0002newchain_0
    I: [OK]          ././iptables/tests/shell/testcases/chain/0003rename_1
    I: [OK]          ././iptables/tests/shell/testcases/ebtables/0001-ebtables-
basic_0
    I: [OK]          ././iptables/tests/shell/testcases/firewalld-restore/0001-
firewalld_0
    I: [OK]          ././iptables/tests/shell/testcases/firewalld-restore/0002-
firewalld-restart_0
    I: [OK]          ././iptables/tests/shell/testcases/ipt-restore/0001load-
specific-table_0
    I: [OK]          ././iptables/tests/shell/testcases/ipt-save/0001load-
dumps_0
    I: [OK]          ././iptables/tests/shell/testcases/ipt-save/0002load-
fedora27-firewalld_0
    I: nft results: [OK] 9 [FAILED] 0 [TOTAL] 9
    I: combined results: [OK] 18 [FAILED] 0 [TOTAL] 18

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