Am 21.01.21 um 14:39 schrieb Gert Doering:
> Without this patch, if openpn is using a plugin that provides
> OPENVPN_PLUGIN_ENABLE_PF but then fails (returns OPENVPN_PLUGIN_FUNC_ERROR),
> OpenVPN will crash on a NULL pointer reference.
>
> The underlying cause is (likely) the refactoring work regarding
> CAS_SUCCEEDED etc., and that nobody adjusted the pf.c code accordingly
> (it tries to sent itself a SIGUSR1, which tries to tear down the
> client MI instance, but since it is not fully set up yet at this
> point, things explode). Full details on the call chain in Trac...
>
> Since we intend to remove pf in 2.6, but we still do not want OpenVPN
> to ever SIGSEGV, change the requirements for the plugins to "MUST SUCCEED",
> so if the plugin ENABLE_PF call fails, abort openvpn with a M_FATAL
> message.
>
> Trac: #1377
>
> Signed-off-by: Gert Doering <g...@greenie.muc.de>
> ---
> src/openvpn/pf.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/src/openvpn/pf.c b/src/openvpn/pf.c
> index f9bbfb50..3f472ef4 100644
> --- a/src/openvpn/pf.c
> +++ b/src/openvpn/pf.c
> @@ -639,8 +639,17 @@ pf_init_context(struct context *c)
> }
> if (!c->c2.pf.enabled)
> {
> - msg(M_WARN, "WARNING: failed to init PF plugin, rejecting
> client.");
> - register_signal(c, SIGUSR1, "plugin-pf-init-failed");
> + /* At some point in openvpn history, this code just printed a
> + * warning and signalled itself (SIGUSR1,
> "plugin-pf-init-failed")
> + * to terminate the client instance. This got broken at one of
> + * the client auth state refactorings (leading to SIGSEGV
> crashes)
> + * and due to "pf will be removed anyway" reasons the easiest way
> + * to prevent crashes is to REQUIRE that plugins succeed - so if
> + * the plugin fails, we cleanly abort OpenVPN
> + *
> + * see also: https://community.openvpn.net/openvpn/ticket/1377
> + */
> + msg(M_FATAL, "FATAL: failed to init PF plugin, must succeed.");
> return;
> }
> }
>
Acked-By: Arne Schwabe <a...@rfc2549.org>
I agree to make this "fixed" in a way that doesn't involve refactoring
of pf code that is later removed anyway. I don't think the refactoring
early affects this. It has been probably broken even earlier.
Arne
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