With the sequence numbers we don't have to maintain the reqid to delete
the temporary state.
One exception is with labels. There we currently only install trap
policies with the generic label. SAs created from those don't have
policies installed, so we have to reuse the reqid of the trap even if
narrowing occurs.
And as before, we reuse the reqid without checking traffic selectors if
sequence numbers are not supported.
Note that if a CHILD_SA is manually initiated (i.e. has no sequence
number assigned) right before an acquire is triggered, there are several
possible outcomes depending on whether narrowing occurs. If there is no
narrowing, the same reqid is assigned and the kernel will remove the
temporary SA when the SA is installed (no seq => reqid match).
Afterwards, the queued duplicate CHILD_SA is destroyed and the acquire
state in the trap manager gets removed. If there is narrowing, a new
reqid is allocated, so the installation of the SA will not remove the
temporary state. However, due to the narrowing, the duplicate check
fails and when the duplicate is installed (with sequence number), the
temporary state is deleted (as is the state in the trap manager).
Every reqid is allocated once, we don't store the same reqid with e.g.
different marks or interface IDs that would make it necessary to make
them part of the key in that table (that's different in the other table).
To preserve the current behavior, that is, allocating a new reqid if e.g.
the marks are different, the additional selector values (which will
result in an additional policy in the Linux kernel) are compared after
the initial lookup.
Enables us to ignore any future kernel features for routes unless
we actually need to consider them for the source IP routes.
Also enables us to actually really skip IPsec processing for those networks
(because even the routes don't touch those packets). It's more what
users expect.
Co-authored-by: Tobias Brunner <[email protected]>
This is mainly an issue on FreeBSD where the current kernel still only
allows the daemon to use reqids < IPSEC_MANUAL_REQID_MAX (0x3fff = 16383).
Fixes#2315.
Tobias Brunner