all open TCP connections in tcp_slowtimo() (which is called 2x
per second). It's fairly rare for TCP timers to actually fire,
so saving this list traversal is good, especially if you want
to scale to thousands of open connections.
network interfaces. This works by pre-computing the pseudo-header
checksum and caching it, delaying the actual checksum to ip_output()
if the hardware cannot perform the sum for us. In-bound checksums
can either be fully-checked by hardware, or summed up for final
verification by software. This method was modeled after how this
is done in FreeBSD, although the code is significantly different in
most places.
We don't delay checksums for IPv6/TCP, but we do take advantage of the
cached pseudo-header checksum.
Note: hardware-assisted checksumming defaults to "off". It is
enabled with ifconfig(8). See the manual page for details.
Implement hardware-assisted checksumming on the DP83820 Gigabit Ethernet,
3c90xB/3c90xC 10/100 Ethernet, and Alteon Tigon/Tigon2 Gigabit Ethernet.
ISS attacks (which we already fend off quite well).
1. First-cut implementation of RFC1948, Steve Bellovin's cryptographic
hash method of generating TCP ISS values. Note, this code is experimental
and disabled by default (experimental enough that I don't export the
variable via sysctl yet, either). There are a couple of issues I'd
like to discuss with Steve, so this code should only be used by people
who really know what they're doing.
2. Per a recent thread on Bugtraq, it's possible to determine a system's
uptime by snooping the RFC1323 TCP timestamp options sent by a host; in
4.4BSD, timestamps are created by incrementing the tcp_now variable
at 2 Hz; there's even a company out there that uses this to determine
web server uptime. According to Newsham's paper "The Problem With
Random Increments", while NetBSD's TCP ISS generation method is much
better than the "random increment" method used by FreeBSD and OpenBSD,
it is still theoretically possible to mount an attack against NetBSD's
method if the attacker knows how many times the tcp_iss_seq variable
has been incremented. By not leaking uptime information, we can make
that much harder to determine. So, we avoid the leak by giving each
TCP connection a timebase of 0.
- let ipfilter look at wire-format packet only (not the decapsulated ones),
so that VPN setting can work with NAT/ipfilter settings.
sync with kame.
TODO: use header history for stricter inbound validation
mandatory for IPv6 (so we can't just validate by using connected pcb - we need
to allow traffic from unconnected pcb to do pmtud).
- if the traffic is validated by xx_ctlinput, allow up to "hiwat" pmtud
route entries.
- if the traffic was not validated by xx_ctlinput, allow up to "lowat" pmtud
route entries (there's upper limit, so bad guys cannot blow up our routing
table).
sync with kame
XXX need to think again about default hiwat/lowat value.
XXX victim selection to help starvation case
TODO: udp6, and sendto consideration. as pmtud is mandatory for IPv6,
it is rather important for us to support those cases.
TODO: more testing
TODO: kame sync
entering rtentry's for hosts we're not actually communicating
with.
Do this by invoking the ctlinput for the protocol, which is
responsible for validating the ICMP message:
* TCP -- Lookup the connection based on the address/port
pairs in the ICMP message.
* AH/ESP -- Lookup the SA based on the SPI in the ICMP message.
If validation succeeds, ctlinput is responsible for calling
icmp_mtudisc(). icmp_mtudisc() then invokes callbacks registered
by protocols (such as TCP) which want to take some sort of special
action when a path's MTU changes. For TCP, this is where we now
refresh cached routes and re-enter slow-start.
As a side-effect, this fixes the problem where TCP would not be
notified when a path's MTU changed if AH/ESP were being used.
XXX Note, this is only a fix for the IPv4 case. For the IPv6
XXX case, we need to wait for the KAME folks.
Reviewed by sommerfeld@netbsd.org and itojun@netbsd.org.
ip_output(). This flag, if set, causes ip_output() to set
DF in the IP header if the MTU in the route is not locked.
This allows a bunch of redundant code, which I was never
really all that happy about adding in the first place, to
be eliminated.
Inspired by a similar change made by provos@openbsd.org when
he integrated NetBSD's Path MTU Discovery code into OpenBSD.
this avoids too aggressive memory usage on heavy load web server, for example.
From: Kevin Lahey <kml@dotrocket.com>
release and reallocate t_template, if t_template->m_len changes.
(this happens if we connect to IPv4 mapped destination and then IPv6
destination, on a single AF_INET6 socket)
KAME 1.26 -> 1.28
between protocol handlers.
ipsec socket pointers, ipsec decryption/auth information, tunnel
decapsulation information are in my mind - there can be several other usage.
at this moment, we use this for ipsec socket pointer passing. this will
avoid reuse of m->m_pkthdr.rcvif in ipsec code.
due to the change, MHLEN will be decreased by sizeof(void *) - for example,
for i386, MHLEN was 100 bytes, but is now 96 bytes.
we may want to increase MSIZE from 128 to 256 for some of our architectures.
take caution if you use it for keeping some data item for long period
of time - use extra caution on M_PREPEND() or m_adj(), as they may result
in loss of m->m_pkthdr.aux pointer (and mbuf leak).
this will bump kernel version.
(as discussed in tech-net, tested in kame tree)
- interop issues in ipcomp is fixed
- padding type (after ESP) is configurable
- key database memory management (need more fixes)
- policy specification is revisited
XXX m->m_pkthdr.rcvif is still overloaded - hope to fix it soon
due to massive changes in KAME side.
- IPv6 output goes through nd6_output
- faith can capture IPv4 packets as well - you can run IPv4-to-IPv6 translator
using heavily modified DNS servers
- per-interface statistics (required for IPv6 MIB)
- interface autoconfig is revisited
- udp input handling has a big change for mapped address support.
- introduce in4_cksum() for non-overwriting checksumming
- introduce m_pulldown()
- neighbor discovery cleanups/improvements
- netinet/in.h strictly conforms to RFC2553 (no extra defs visible to userland)
- IFA_STATS is fixed a bit (not tested)
- and more more more.
TODO:
- cleanup os-independency #ifdef
- avoid rcvif dual use (for IPsec) to help ifdetach
(sorry for jumbo commit, I can't separate this any more...)
MSS advertisement must always be:
max(if mtu) - ip hdr siz - tcp hdr siz
We violated this in the previous code so it was fixed.
tcp_mss_to_advertise() now takes af (af on wire) as its argument,
to compute right ip hdr siz.
tcp_segsize() will take care of IPsec header size.
One thing I'm not really sure is how to handle IPsec header size in
*rxsegsizep (inbound segment size estimation).
The current code subtracts possible *outbound* IPsec size from *rxsegsizep,
hoping that the peer is using the same IPsec policy as me.
It may not be applicable, could TCP gulu please comment...
Stale syn cache entries are useless because none of them will be used
if there is no listening socket, as tcp_input looks up listening socket by
in_pcblookup*() before looking into syn cache.
This fixes race condition due to dangling socket pointer from syn cache
entries to listening socket (this was introduced when ipsec is merged in).
This should preserve currently implemented behavior (but not 4.4BSD
behavior prior to syn cache).
Tested in KAME repository before commit, but we'd better run some
regression tests.
is not the expected one.
I see PRC_REDIRECT_HOST with sa->sa_family == AF_UNIX coming to
{tcp,udp}_ctlinput() when I use dhclient, and I feel like adding
more sanity checks, without logging - if we log it it is too noisy.
when ip header and tcp header are not adjacent to each other
(i.e. when ip6 options are attached).
To test this, try
telnet @::1@::1 port
toward a port without responding server. Prior to the fix, the kernel will
generate broken RST packet.
thorpej