Description:
- A BSD pseudo-device initialization routine is declared as
void <pseudo-device name>attach __P((int count));
in ioconf.c by config(8). main() calls these functions
from a table.
- IP Filter has functions iplattach() and ipldetach() (or,
in the NetBSD case, were erroneously renamed ipfilterattach()
and ipfilterdetach()). These functions are used to establish
and disestablish the IP Filter "filter rule check" hook in
the IP input/output stream. They are declared:
int iplattach __P((void));
int ipldetach __P((void));
..and are expected to return a value by iplioctl().
- When main() calls (by sheer coincidence!) iplattach(),
the filter hook is established, and the IP Filter machinery
labeled as "initialized". This causes all packets, whether or
not the user intents to use filter rules, to be passed to
the filter rule checker if "ipfilter" is configured into the
kernel.
- As a result of the above, a kludge existed to default to
passing all packets (I can only assume that when this was
originally committed, the symptom of the bug was noticed by
the integrator, but the bug not actually found/fixed).
- In iplioctl(), if the SIOCFRENB ioctl is issued with an
argument of "enable" (i.e. user executed "ipf -E"), iplattach()
will notice that the machinery is already initialized and
return EBUSY.
Fix:
- Rename iplattach()/ipldetach() to ipl_enable() and ipl_disable().
- Create a pseudo-device entry stub named ipfilterattach()
(NetBSD case) or iplattach() (all other). This is a noop; none
of the machinery should be initialized until the caller expicitly
enables the filter with ipf -E. Add a comment to note that.
XXX !!! XXX !!!
I noticed a few semi-serious bugs while doing this merge, one of which
has existed for a fairly long time. Some of them are addressed in this
commit (because they caused the kernel to not compile), and are annoted
by "XXX" and "--thorpej". The other one will be addressed shortly in
a future commit, and, as far as I can tell, affects all operating systems
which IP Filter supports.
Among other, add ARPHRD_ARCNET definition, make sure the hardware type is
set on outgoing ARP packets, make sure we dont send out replies as broadcasts.
Some of the stuff (e.g., rarpd, bootpd, dhcpd etc., libsa) still will
only support Ethernet. Tcpdump itself should be ok, but libpcap needs
lot of work.
For the detailed change history, look at the commit log entries for
the is-newarp branch.
routed packets. This currently defaults to `drop,' but once we
verify that all applications that rely on determining remote IP
addresses for authentication are dropping the connection when they
see a source route option (not just disabling the source route
option), we can turn this back on and conform with the host
requirements.
interface using a sockaddr_dl in a control mbuf.
Implement SO_TIMESTAMP for IP datagrams.
Move packet information option processing into a generic function
so that they work with multicast UDP and raw IP as well as unicast UDP.
Contributed by Bill Fenner <fenner@parc.xerox.com>.
Scenario: If ip_insertoptions() prepends a new mbuf to the chain, the
bad: label's m_freem(m0) still would free only the original mbuf chain
if the transmission failed for, e.g., no route to host; resulting in
one lost mbuf per failed packet. (The original posting included a
demonstration program).
Original report of this bug was by jinmei@isl.rdc.toshiba.co.jp
(JINMEI Tatuya) on comp.bugs.4bsd.
augustss