A complete rationale and discussion is given in this message
and the resulting discussion:
http://docs.freebsd.org/cgi/mid.cgi?4177C8AD.6060706
Note that this commit removes only the functional part of T/TCP
from the tcp_* related functions in the kernel. Other features
introduced with RFC1644 are left intact (socket layer changes,
sendmsg(2) on connection oriented protocols) and are meant to
be reused by a simpler and less intrusive reimplemention of the
previous T/TCP functionality.
Discussed on: -arch
of protocols. The call to divert_packet() is done through a function pointer. All
semantics of IPDIVERT remain intact. If IPDIVERT is not loaded ipfw will refuse to
install divert rules and natd will complain about 'protocol not supported'. Once
it is loaded both will work and accept rules and open the divert socket. The module
can only be unloaded if no divert sockets are open. It does not close any divert
sockets when an unload is requested but will return EBUSY instead.
passing along socket information. This is required to work around a LOR with
the socket code which results in an easy reproducible hard lockup with
debug.mpsafenet=1. This commit does *not* fix the LOR, but enables us to do
so later. The missing piece is to turn the filter locking into a leaf lock
and will follow in a seperate (later) commit.
This will hopefully be MT5'ed in order to fix the problem for RELENG_5 in
forseeable future.
Suggested by: rwatson
A lot of work by: csjp (he'd be even more helpful w/o mentor-reviews ;)
Reviewed by: rwatson, csjp
Tested by: -pf, -ipfw, LINT, csjp and myself
MFC after: 3 days
LOR IDs: 14 - 17 (not fixed yet)
the ipfw KLD.
For IPFIREWALL_FORWARD this does not have any side effects. If the module
has it but not the kernel it just doesn't do anything.
For IPDIVERT the KLD will be unloadable if the kernel doesn't have IPDIVERT
compiled in too. However this is the least disturbing behaviour. The user
can just recompile either module or the kernel to match the other one. The
access to the machine is not denied if ipfw refuses to load.
and preserves the ipfw ABI. The ipfw core packet inspection and filtering
functions have not been changed, only how ipfw is invoked is different.
However there are many changes how ipfw is and its add-on's are handled:
In general ipfw is now called through the PFIL_HOOKS and most associated
magic, that was in ip_input() or ip_output() previously, is now done in
ipfw_check_[in|out]() in the ipfw PFIL handler.
IPDIVERT is entirely handled within the ipfw PFIL handlers. A packet to
be diverted is checked if it is fragmented, if yes, ip_reass() gets in for
reassembly. If not, or all fragments arrived and the packet is complete,
divert_packet is called directly. For 'tee' no reassembly attempt is made
and a copy of the packet is sent to the divert socket unmodified. The
original packet continues its way through ip_input/output().
ipfw 'forward' is done via m_tag's. The ipfw PFIL handlers tag the packet
with the new destination sockaddr_in. A check if the new destination is a
local IP address is made and the m_flags are set appropriately. ip_input()
and ip_output() have some more work to do here. For ip_input() the m_flags
are checked and a packet for us is directly sent to the 'ours' section for
further processing. Destination changes on the input path are only tagged
and the 'srcrt' flag to ip_forward() is set to disable destination checks
and ICMP replies at this stage. The tag is going to be handled on output.
ip_output() again checks for m_flags and the 'ours' tag. If found, the
packet will be dropped back to the IP netisr where it is going to be picked
up by ip_input() again and the directly sent to the 'ours' section. When
only the destination changes, the route's 'dst' is overwritten with the
new destination from the forward m_tag. Then it jumps back at the route
lookup again and skips the firewall check because it has been marked with
M_SKIP_FIREWALL. ipfw 'forward' has to be compiled into the kernel with
'option IPFIREWALL_FORWARD' to enable it.
DUMMYNET is entirely handled within the ipfw PFIL handlers. A packet for
a dummynet pipe or queue is directly sent to dummynet_io(). Dummynet will
then inject it back into ip_input/ip_output() after it has served its time.
Dummynet packets are tagged and will continue from the next rule when they
hit the ipfw PFIL handlers again after re-injection.
BRIDGING and IPFW_ETHER are not changed yet and use ipfw_chk() directly as
they did before. Later this will be changed to dedicated ETHER PFIL_HOOKS.
More detailed changes to the code:
conf/files
Add netinet/ip_fw_pfil.c.
conf/options
Add IPFIREWALL_FORWARD option.
modules/ipfw/Makefile
Add ip_fw_pfil.c.
net/bridge.c
Disable PFIL_HOOKS if ipfw for bridging is active. Bridging ipfw
is still directly invoked to handle layer2 headers and packets would
get a double ipfw when run through PFIL_HOOKS as well.
netinet/ip_divert.c
Removed divert_clone() function. It is no longer used.
netinet/ip_dummynet.[ch]
Neither the route 'ro' nor the destination 'dst' need to be stored
while in dummynet transit. Structure members and associated macros
are removed.
netinet/ip_fastfwd.c
Removed all direct ipfw handling code and replace it with the new
'ipfw forward' handling code.
netinet/ip_fw.h
Removed 'ro' and 'dst' from struct ip_fw_args.
netinet/ip_fw2.c
(Re)moved some global variables and the module handling.
netinet/ip_fw_pfil.c
New file containing the ipfw PFIL handlers and module initialization.
netinet/ip_input.c
Removed all direct ipfw handling code and replace it with the new
'ipfw forward' handling code. ip_forward() does not longer require
the 'next_hop' struct sockaddr_in argument. Disable early checks
if 'srcrt' is set.
netinet/ip_output.c
Removed all direct ipfw handling code and replace it with the new
'ipfw forward' handling code.
netinet/ip_var.h
Add ip_reass() as general function. (Used from ipfw PFIL handlers
for IPDIVERT.)
netinet/raw_ip.c
Directly check if ipfw and dummynet control pointers are active.
netinet/tcp_input.c
Rework the 'ipfw forward' to local code to work with the new way of
forward tags.
netinet/tcp_sack.c
Remove include 'opt_ipfw.h' which is not needed here.
sys/mbuf.h
Remove m_claim_next() macro which was exclusively for ipfw 'forward'
and is no longer needed.
Approved by: re (scottl)
Since the only thing truly unique about a prison is it's ID, I figured
this would be the most granular way of handling this.
This commit makes the following changes:
- Adds tokenizing and parsing for the ``jail'' command line option
to the ipfw(8) userspace utility.
- Append the ipfw opcode list with O_JAIL.
- While Iam here, add a comment informing others that if they
want to add additional opcodes, they should append them to the end
of the list to avoid ABI breakage.
- Add ``fw_prid'' to the ipfw ucred cache structure.
- When initializing ucred cache, if the process is jailed,
set fw_prid to the prison ID, otherwise set it to -1.
- Update man page to reflect these changes.
This change was a strong motivator behind the ucred caching
mechanism in ipfw.
A sample usage of this new functionality could be:
ipfw add count ip from any to any jail 2
It should be noted that because ucred based constraints
are only implemented for TCP and UDP packets, the same
applies for jail associations.
Conceptual head nod by: pjd
Reviewed by: rwatson
Approved by: bmilekic (mentor)
For incoming packets, the packet's source address is checked if it
belongs to a directly connected network. If the network is directly
connected, then the interface the packet came on in is compared to
the interface the network is connected to. When incoming interface
and directly connected interface are not the same, the packet does
not match.
Usage example:
ipfw add deny ip from any to any not antispoof in
Manpage education by: ru
RTF_BLACKHOLE as well.
To quote the submitter:
The uRPF loose-check implementation by the industry vendors, at least on Cisco
and possibly Juniper, will fail the check if the route of the source address
is pointed to Null0 (on Juniper, discard or reject route). What this means is,
even if uRPF Loose-check finds the route, if the route is pointed to blackhole,
uRPF loose-check must fail. This allows people to utilize uRPF loose-check mode
as a pseudo-packet-firewall without using any manual filtering configuration --
one can simply inject a IGP or BGP prefix with next-hop set to a static route
that directs to null/discard facility. This results in uRPF Loose-check failing
on all packets with source addresses that are within the range of the nullroute.
Submitted by: James Jun <james@towardex.com>
using M_PROTO6 and possibly shooting someone's foot, as well as allowing the
firewall to be used in multiple passes, or with a packet classifier frontend,
that may need to explicitly allow a certain packet. Presently this is handled
in the ipfw_chk code as before, though I have run with it moved to upper
layers, and possibly it should apply to ipfilter and pf as well, though this
has not been investigated.
Discussed with: luigi, rwatson
for unknown events.
A number of modules return EINVAL in this instance, and I have left
those alone for now and instead taught MOD_QUIESCE to accept this
as "didn't do anything".
Giant if debug.mpsafenet=0, as any points that require synchronization
in the SMPng world also required it in the Giant-world:
- inpcb locks (including IPv6)
- inpcbinfo locks (including IPv6)
- dummynet subsystem lock
- ipfw2 subsystem lock
ruleset, the pcb is looked up once per ipfw_chk() activation.
This is done by extracting the required information out of the PCB
and caching it to the ipfw_chk() stack. This should greatly reduce
PCB looking contention and speed up the processing of UID/GID based
firewall rules (especially with large UID/GID rulesets).
Some very basic benchmarks were taken which compares the number
of in_pcblookup_hash(9) activations to the number of firewall
rules containing UID/GID based contraints before and after this patch.
The results can be viewed here:
o http://people.freebsd.org/~csjp/ip_fw_pcb.png
Reviewed by: andre, luigi, rwatson
Approved by: bmilekic (mentor)
process is a non-prison root. The security.jail.allow_raw_sockets
sysctl variable is disabled by default, however if the user enables
raw sockets in prisons, prison-root should not be able to interact
with firewall rule sets.
Approved by: rwatson, bmilekic (mentor)
source address of a packet exists in the routing table. The
default route is ignored because it would match everything and
render the check pointless.
This option is very useful for routers with a complete view of
the Internet (BGP) in the routing table to reject packets with
spoofed or unrouteable source addresses.
Example:
ipfw add 1000 deny ip from any to any not versrcreach
also known in Cisco-speak as:
ip verify unicast source reachable-via any
Reviewed by: luigi
them mostly with packet tags (one case is handled by using an mbuf flag
since the linkage between "caller" and "callee" is direct and there's no
need to incur the overhead of a packet tag).
This is (mostly) work from: sam
Silence from: -arch
Approved by: bms(mentor), sam, rwatson
code is compiled in to support the O_IPSEC operator. Previously no
support was included and ipsec rules were always matching. Note that
we do not return an error when an ipsec rule is added and the kernel
does not have IPsec support compiled in; this is done intentionally
but we may want to revisit this (document this in the man page).
PR: 58899
Submitted by: Bjoern A. Zeeb
Approved by: re (rwatson)
for ipfw processing w/o an indication the packets were generated
by ipfw--and so should not be processed (this manifested itself
as a LOR.) The flag bit in the mbuf that was used to mark the
packets was not listed in M_COPYFLAGS so if a packet had a header
prepended (as done by IPsec) the flag was lost. Correct this by
defining a new M_PROTO6 flag and use it to mark packets that need
this processing.
Reviewed by: bms
Approved by: re (rwatson)
MFC after: 2 weeks
the routing table. Move all usage and references in the tcp stack
from the routing table metrics to the tcp hostcache.
It caches measured parameters of past tcp sessions to provide better
initial start values for following connections from or to the same
source or destination. Depending on the network parameters to/from
the remote host this can lead to significant speedups for new tcp
connections after the first one because they inherit and shortcut
the learning curve.
tcp_hostcache is designed for multiple concurrent access in SMP
environments with high contention and is hash indexed by remote
ip address.
It removes significant locking requirements from the tcp stack with
regard to the routing table.
Reviewed by: sam (mentor), bms
Reviewed by: -net, -current, core@kame.net (IPv6 parts)
Approved by: re (scottl)
accordingly. The define is left intact for ABI compatibility
with userland.
This is a pre-step for the introduction of tcp_hostcache. The
network stack remains fully useable with this change.
Reviewed by: sam (mentor), bms
Reviewed by: -net, -current, core@kame.net (IPv6 parts)
Approved by: re (scottl)
complex locking and rework ip_rtaddr() to do its own rtlookup.
Adopt all its callers to this and make ip_output() callable
with NULL rt pointer.
Reviewed by: sam (mentor)
has a LOR between IPFW inpcb locks but I'm committing it now as the
lesser of two evils (the other being unlocked use of in_pcblookup).
Supported by: FreeBSD Foundation
if_xname, if_dname, and if_dunit. if_xname is the name of the interface
and if_dname/unit are the driver name and instance.
This change paves the way for interface renaming and enhanced pseudo
device creation and configuration symantics.
Approved By: re (in principle)
Reviewed By: njl, imp
Tested On: i386, amd64, sparc64
Obtained From: NetBSD (if_xname)
trashed after being freed. This has caused several panics including
kern/42277 related to soft updates. Jim Kuhn tracked the problem
down to ipfw limit rule processing. In the expiry of dynamic rules,
it is possible for an O_LIMIT_PARENT rule to be removed when it still
has live children. When the children eventually do expire, a pointer
to the (long gone) parent is dereferenced and a count decremented.
Since this memory can, and is, allocated for other purposes (in the
case of kern/42277 an inodedep structure), chaos ensues. The offset
in question in inodedep is the offset of the 16 bit count field in
the ipfw2 ipfw_dyn_rule.
Submitted by: Jim Kuhn <jkuhn@sandvine.com>
Reviewed by: "Evgueni V. Gavrilov" <aquatique@rusunix.org>
Reviewed by: Ben Pfountz <netprince@vt.edu>
MFC after: 1 week
sending an ICMP packet doesn't cause a panic. A better solution is needed;
possibly defering the transmit to a dedicated thread.
Observed by: "Aaron Wohl" <freebsd@soith.com>
o change timeout to MPSAFE callout
o restructure rule deletion to deal with locking requirements
o replace static buffer used for ipfw control operations with malloc'd storage
Sponsored by: FreeBSD Foundation
Set 31 is still special because rules belonging to it are not deleted
by the "ipfw flush" command, but must be deleted explicitly with
"ipfw delete set 31" or by individual rule numbers.
This implement a flexible form of "persistent rules" which you might
want to have available even after an "ipfw flush".
Note that this change does not violate POLA, because you could not
use set 31 in a ruleset before this change.
sbin/ipfw changes to allow manipulation of set 31 will follow shortly.
Suggested by: Paul Richards
Since we already had 'O_NOP' instructions which always match, all
I needed to do is allow the NOP command to have arbitrary length
(i.e. move its label in a different part of the switch() which
validates instructions).
The kernel must know nothing about comments, everything else is
done in userland (which will be described in the upcoming ipfw2.c
commit).
support matching a list of addr/mask pairs so one can write
more efficient rulesets which were not possible before e.g.
add 100 skipto 1000 not src-ip 10.0.0.0/8,127.0.0.1/8,192.168.0.0/16
The change is fully backward compatible.
ipfw2 and manpage commit to follow.
MFC after: 3 days
