Re: git: cfa1a1308709 - main - pfctl: fix recrusive printing of ethernet anchors

[Matteo Riondato]

On 2022-10-18 at 04:44 EDT, Kristof Provost <k...@freebsd.org> wrote:

On 17 Oct 2022, at 19:37, Matteo Riondato wrote:

On 2022-10-07 at 06:13 EDT, Kristof Provost <k...@freebsd.org> wrote:

On 3 Oct 2022, at 18:13, Bryan Drewery wrote:

I think there's still a problem here.

pfctl -a '*' -sr works pfctl -a 'name/*' -sr does not.

So I’ve looked at this a bit more, and I am now going to back away from the whole anchor thing, and try to pretend I didn’t see any of the tentacled horrors that lurk within.

To give you an idea of the issues, loading the following ruleset:

        anchor "foo" {
                anchor "bar" {
                        pass in
                }
        }

does exactly what you’d expect:

        # pfctl -sr -a "*"
        anchor "foo" all {
          anchor "bar" all {
            pass in all flags S/SA keep state
          }
        }
        # pfctl -sr -a "foo/*"
        anchor "bar" all {
          pass in all flags S/SA keep state
        }

However, if we `pfctl -Fr` to flush all rules:

        # pfctl -Fr
        rules cleared
        # pfctl -sr -a "*"
        # pfctl -sr -a "foo/*"
        anchor "bar" all {
          pass in all flags S/SA keep state
        }

How is one supposed to know which rules are really loaded in this case? Printing of rules with anchors being broken (I even get a segmentation fault with 'pfctl -a "*" -sr -vv') makes debugging rulesets very hard.

`pfctl -a "*" -sr` should always produce the expected results, at least as far as I know.

anchor "foo" all {
  anchor "bar" all {
        pass in all flags S/SA keep state
        }
}

I'm wondering what gets printed if you load a ruleset such as:

block all
anchor "foo" all {
  pass in all proto udp
  anchor "bar" all {
        pass in all proto tcp flags S/SA keep state
        }
}



anchor "foo" all {
  pass in all proto udp
  anchor "bar" all {
        pass in all proto tcp flags S/SA keep state
        }
}

The last example above clearly shows that `pfctl -a "*"` does *not* always produce the expected results: after flushing the rules in the root anchor with `pfctl -Fr`, `pfctl -sr -a '*'` does *not* produce the expected results, which would have been Then print it with `pfctl -sr -a '*'`, then do a `pfctl -Fr`, and then do another `pfctl -sr -a '*'`, followed by a `pfctl -sr -a "foo/*"`. I expect to see, again nothing for the `pfctl -sr -a '*'` after the flush, and something like the following for the `pfctl -sr -a "foo/*"`: which at least would (partially?) confirm that `pfctl -Fr` only flushes rules in the root anchor.

I’d be very interested in seeing a test case where that core dumps, because that is indeed very annoying, and might be something I can fix.

I'll try to come up with a minimally reproducible case (it is totally reproducible with my settings, but I'd like to give you something smaller).

Partially, the question I also have is: is printing of rules broken, or is flushing of rules broken, or a third thing? =)

To the extent that I currently understand this problem I believe the issue is that we’re not always stepping into child anchors to print them. I believe they do get evaluated when the rules are processed. So it’s the printing that’s broken. The flushing is .. not broken, but may not do what you’d expect. When we flush we only flush the root anchor, and other anchors can remain. I think that’s the main source of the strange behaviour I’ve described.

Thanks,
Matteo

Assuming that indeed `pfctl -Fr` really only acts on the root anchor, what makes me worried is whether rules inside child anchors are really evaluated *after* a flush of those in the root anchor with `pfctl -Fr`, but checking if they really are evaluated should be an easy test.

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