If we silently delete the IKE_SA the other peer might still use it even
if only to send DPDs. If we don't answer to DPDs that might result in the
deletion of the new IKE_SA too.
This is the minimum size an IPv6 implementation must support. This makes
it the default for IPv4 too, which presumably is also generally routable
(otherwise, setting this to 0 falls back to the minimum of 576 for IPv4).
The maximum would not get set correctly when a logger is removed and the
first remaining logger in the list (the one with the highest log level) does
e.g. only implement vlog() while there are other loggers that implement log().
This would result in only max_vlevel getting set correctly while max_level
would incorrectly get set to -1 so that log() would not get called for any
of the loggers anymore.
References #574.
The kernel will apply the mask to the mark on the packet and then
compare it to the configured mark. So to match only unmarked packets we
have to be able to set 0/0xffffffff.
If the number of flows over a gateway exceeds the flow cache size of the Linux
kernel, policy lookup gets very expensive. Policies covering more than a single
address don't get hash-indexed by default, which results in wasting most of
the cycles in xfrm_policy_lookup_bytype() and its xfrm_policy_match() use.
Starting with several hundred policies the overhead gets inacceptable.
Starting with Linux 3.18, Linux can hash the first n-bit of a policy subnet
to perform indexed lookup. With correctly chosen netbits, this can completely
eliminate the performance impact of policy lookups, freeing the resources
for ESP crypto.
WARNING: Due to a bug in kernels 3.19 through 4.7, the kernel crashes with a
NULL pointer dereference if a socket policy is installed while hash thresholds
are changed. And because the hashtable rebuild triggered by the threshold
change that causes this is scheduled it might also happen if the socket
policies are seemingly installed after setting the thresholds.
The fix for this bug - 6916fb3b10b3 ("xfrm: Ignore socket policies when
rebuilding hash tables") - is included since 4.8 (and might get backported).
As a workaround `charon.plugins.kernel-netlink.port_bypass` may be enabled
to replace the socket policies that allow IKE traffic with port specific
bypass policies.
They are only required if drop policies would otherwise prevent
forwarding traffic. This reduces the number of policies and avoids
conflicts e.g. with SPD hash thresholds.
In case an external thread calls into our code and logs messages, a thread
object is allocated that will never be released. Even if we try to clean
up the object via thread value destructor there is no guarantee that the
thread actually terminates before we check for leaks, which seems to be the
case for the Ada Tasking threads.
Some of these are pretty broad, so maybe an alternative option is to
not use the soup plugin in the openssl-ikev2/rw-suite-b* scenarios. But
the plugin is not tested anywhere else so lets go with this for now.
Tobias Brunner