This code makes use of variable-size kernel representation of rules
(exactly the same concept of BPF instructions, as used in the BSDI's
firewall), which makes firewall operation a lot faster, and the
code more readable and easier to extend and debug.
The interface with the rest of the system is unchanged, as witnessed
by this commit. The only extra kernel files that I am touching
are if_fw.h and ip_dummynet.c, which is quite tied to ipfw. In
userland I only had to touch those programs which manipulate the
internal representation of firewall rules).
The code is almost entirely new (and I believe I have written the
vast majority of those sections which were taken from the former
ip_fw.c), so rather than modifying the old ip_fw.c I decided to
create a new file, sys/netinet/ip_fw2.c . Same for the user
interface, which is in sbin/ipfw/ipfw2.c (it still compiles to
/sbin/ipfw). The old files are still there, and will be removed
in due time.
I have not renamed the header file because it would have required
touching a one-line change to a number of kernel files.
In terms of user interface, the new "ipfw" is supposed to accepts
the old syntax for ipfw rules (and produce the same output with
"ipfw show". Only a couple of the old options (out of some 30 of
them) has not been implemented, but they will be soon.
On the other hand, the new code has some very powerful extensions.
First, you can put "or" connectives between match fields (and soon
also between options), and write things like
ipfw add allow ip from { 1.2.3.4/27 or 5.6.7.8/30 } 10-23,25,1024-3000 to any
This should make rulesets slightly more compact (and lines longer!),
by condensing 2 or more of the old rules into single ones.
Also, as an example of how easy the rules can be extended, I have
implemented an 'address set' match pattern, where you can specify
an IP address in a format like this:
10.20.30.0/26{18,44,33,22,9}
which will match the set of hosts listed in braces belonging to the
subnet 10.20.30.0/26 . The match is done using a bitmap, so it is
essentially a constant time operation requiring a handful of CPU
instructions (and a very small amount of memmory -- for a full /24
subnet, the instruction only consumes 40 bytes).
Again, in this commit I have focused on functionality and tried
to minimize changes to the other parts of the system. Some performance
improvement can be achieved with minor changes to the interface of
ip_fw_chk_t. This will be done later when this code is settled.
The code is meant to compile unmodified on RELENG_4 (once the
PACKET_TAG_* changes have been merged), for this reason
you will see #ifdef __FreeBSD_version in a couple of places.
This should minimize errors when (hopefully soon) it will be time
to do the MFC.
packet forwarding state ("annotations") during ip processing.
The code is considerably cleaner now.
The variables removed by this change are:
ip_divert_cookie used by divert sockets
ip_fw_fwd_addr used for transparent ip redirection
last_pkt used by dynamic pipes in dummynet
Removal of the first two has been done by carrying the annotations
into volatile structs prepended to the mbuf chains, and adding
appropriate code to add/remove annotations in the routines which
make use of them, i.e. ip_input(), ip_output(), tcp_input(),
bdg_forward(), ether_demux(), ether_output_frame(), div_output().
On passing, remove a bug in divert handling of fragmented packet.
Now it is the fragment at offset 0 which sets the divert status of
the whole packet, whereas formerly it was the last incoming fragment
to decide.
Removal of last_pkt required a change in the interface of ip_fw_chk()
and dummynet_io(). On passing, use the same mechanism for dummynet
annotations and for divert/forward annotations.
option IPFIREWALL_FORWARD is effectively useless, the code to
implement it is very small and is now in by default to avoid the
obfuscation of conditionally compiled code.
NOTES:
* there is at least one global variable left, sro_fwd, in ip_output().
I am not sure if/how this can be removed.
* I have deliberately avoided gratuitous style changes in this commit
to avoid cluttering the diffs. Minor stule cleanup will likely be
necessary
* this commit only focused on the IP layer. I am sure there is a
number of global variables used in the TCP and maybe UDP stack.
* despite the number of files touched, there are absolutely no API's
or data structures changed by this commit (except the interfaces of
ip_fw_chk() and dummynet_io(), which are internal anyways), so
an MFC is quite safe and unintrusive (and desirable, given the
improved readability of the code).
MFC after: 10 days
Ipfw processing of frames at layer 2 can be enabled by the sysctl variable
net.link.ether.ipfw=1
Consider this feature experimental, because right now, the firewall
is invoked in the places indicated below, and controlled by the
sysctl variables listed on the right. As a consequence, a packet
can be filtered from 1 to 4 times depending on the path it follows,
which might make a ruleset a bit hard to follow.
I will add an ipfw option to tell if we want a given rule to apply
to ether_demux() and ether_output_frame(), but we have run out of
flags in the struct ip_fw so i need to think a bit on how to implement
this.
to upper layers
| |
+----------->-----------+
^ V
[ip_input] [ip_output] net.inet.ip.fw.enable=1
| |
^ V
[ether_demux] [ether_output_frame] net.link.ether.ipfw=1
| |
+->- [bdg_forward]-->---+ net.link.ether.bridge_ipfw=1
^ V
| |
to devices
+ implement "limit" rules, which permit to limit the number of sessions
between certain host pairs (according to masks). These are a special
type of stateful rules, which might be of interest in some cases.
See the ipfw manpage for details.
+ merge the list pointers and ipfw rule descriptors in the kernel, so
the code is smaller, faster and more readable. This patch basically
consists in replacing "foo->rule->bar" with "rule->bar" all over
the place.
I have been willing to do this for ages!
MFC after: 1 week
splimp() -- we need it because dummynet can be invoked by the
bridging code at splimp().
This should cure the pipe "stalls" that several people have been
reporting on -stable while using bridging+dummynet (the problem
would not affect routers using dummynet).
* Some dummynet code incorrectly handled a malloc()-allocated pseudo-mbuf
header structure, called "pkt," and could consequently pollute the mbuf
free list if it was ever passed to m_freem(). The fix involved passing not
pkt, but essentially pkt->m_next (which is a real mbuf) to the mbuf
utility routines.
* Also, for dummynet, in bdg_forward(), made the code copy the ethernet header
back into the mbuf (prepended) because the dummynet code that follows expects
it to be there but it is, unfortunately for dummynet, passed to bdg_forward
as a seperate argument.
PRs: kern/19551 ; misc/21534 ; kern/23010
Submitted by: Thomas Moestl <tmoestl@gmx.net>
Reviewed by: bmilekic
Approved by: luigi
of the individual drivers and into the common routine ether_input().
Also, remove the (incomplete) hack for matching ethernet headers
in the ip_fw code.
The good news: net result of 1016 lines removed, and this should make
bridging now work with *all* Ethernet drivers.
The bad news: it's nearly impossible to test every driver, especially
for bridging, and I was unable to get much testing help on the mailing
lists.
Reviewed by: freebsd-net
now you can dynamically create rate-limited queues for different
flows using masks on dst/src IP, port and protocols.
Read the ipfw(8) manpage for details and examples.
Restructure the internals of the traffic shaper to use heaps,
so that it manages efficiently large number of queues.
Fix a bug which was present in the previous versions which could
cause, under certain unfrequent conditions, to send out very large
bursts of traffic.
All in all, this new code is much cleaner than the previous one and
should also perform better.
Work supported by Akamba Corp.
pr_input() routines prototype is also changed to support IPSEC and IPV6
chained protocol headers.
Reviewed by: freebsd-arch, cvs-committers
Obtained from: KAME project
routines. The descriptor contains parameters which could be used
within those routines (eg. ip_output() ).
On passing, add IPPROTO_PGM entry to netinet/in.h
+ plug an mbuf leak when dummynet used with bridging
+ make prototype of dummynet_io consistent with usage
+ code cleanup so that now bandwidth regulation is precise to the
bit/s and not to (8*HZ) bit/s as before.
- unifdef -DCOMPAT_IPFW (this was on by default already)
- remove traces of in-kernel ip_nat package, it was never committed.
- Make IPFW and DUMMYNET initialize themselves rather than depend on
compiled-in hooks in ip_init(). This means they initialize the same
way both in-kernel and as kld modules. (IPFW initializes now :-)
the IP header (this would not work for bridged packets).
This has been fixed long ago in the 2.2 branch.
Problem noticed by: a few people
Fix suggested by: Remy Nonnenmacher
problems reported recently (the rtentry pointer in the dummynet
queue was not initialized in all cases, resulting in spurious
rt_refcnt decreases in the lucky cases, and memory trashing in
other cases.
