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author | Alexander Couzens <lynxis@fe80.eu> | 2019-05-17 11:14:46 +0200 |
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committer | Jo-Philipp Wich <jo@mein.io> | 2019-08-22 11:29:42 +0200 |
commit | 8c404ef02f0122ec90b48e122777ff6bfa715d7f (patch) | |
tree | 161071d9f19cdd0f15b77154415882995f88ae71 /includes.c | |
parent | c1d3a4df49c9b9df38b546a1a094e63e107a1074 (diff) | |
download | firewall3-8c404ef02f0122ec90b48e122777ff6bfa715d7f.tar.gz |
iptables.c: lock the xtables.lock
When using fw3 together with other applications or scripts a race
conditions might occur. When fw3 is preparing the new tables, another
application can use the executable `iptables` which modifies the
kernel-tables. libxtables will notify this and fails when fw3 is
committing the changes resulting in a failed firewall.
Now waits in a while loop until the lock is gone, activate the lock
itself and applies changes.
To reproduce the bug the following two scripts should run in parrallel,
after a few seconds the latter stop and leaves a broken firewall:
while true; do iptables -N locking; done
and
while [ "$(iptables -w -L OUTPUT | wc -l)" -gt 2 ]; do fw3 reload; done
The following message will appear
Warning: iptc_commit(): Resource temporarily unavailable
and connectivity is gone.
Tested in an LXC and Qemu container.
Signed-off-by: Alexander Couzens <lynxis@fe80.eu>
[fixed waiting for unlock and commit message]
Signed-off-by: Paul Spooren <mail@aparcar.org>
Diffstat (limited to 'includes.c')
0 files changed, 0 insertions, 0 deletions