Kebe Says - Dan McDonald's Blog

The Volo project is an effort to improve the interface between sockets and any socket-driven subsystems, including the TCP/IP stack. During their testing, they panicked during some IPsec tests. See this bug for what they reported.

In our IPsec, we have LARVAL IPsec security associations (SAs). These are SAs that reserve a unique 32-bit Security Parameters Index (SPI), but have no other data. If a packet arrives for a LARVAL SA, we queue it up, so that when it gets filled in by key management, the packet can go through. We do this because of the IKE Quick Mode Exchange, which looks like this:

        INITIATOR                               RESPONDER
        ---------                               ---------

        IKE Quick Mode Packet #1  ------->

                                <----------     IKE Quick Mode Packet #2

        IKE Quick Mode Packet #3  -------->

Now once the initiator receives Quick Mode packet #2, it has enough information to transmit an IPsec-protected packet. Unfortunately, the responder cannot finish completing its Security Association entries until it receives packet #3. It is possible, then, that the initiator's IPsec packet may arrive before the responder has finished processing IKE. Let's look at the packets again:

        INITIATOR                               RESPONDER
        ---------                               ---------

        IKE Quick Mode Packet #1  ------->

                                <----------     IKE Quick Mode Packet #2

        ESP or AH packet        ---------->     Does this packet...

        IKE Quick Mode Packet #3  -------->     ... get processed after my
                                                receipt of #3, also after
                                                which I SADB_UPDATE my
                                                inbound SA, which changes it
                                                from LARVAL to MATURE?

Now the code that queues up an inbound IPsec packet for a LARVAL SA is sadb_set_lpkt(), as was shown in the bug's description. It turns out there was a locking bug in this function - and we even had an ASSERT()-ion that the SA manipulated by sadb_set_lpkt() was always larval. The problem was, we discounted the possibility of IKE finishing between the detection of a LARVAL SA and the actual call to sadb_set_lpkt().

The Volo project improved UDP latency enough so that the IKE packet wormed its way up the stack and into in.iked faster than the concurrent ESP or AH packet. The aformentioned ASSERT() tripped during Volo testing, because we did not check the SA's state while holding its lock. Had we, we could tell that the LARVAL SA was promoted to ACTIVE, and we could go ahead and process the packet.

This race condition was present since sadb_set_lpkt() was introduced in Solaris 9, but it took Volo's improved performance to find it. So hats off to Volo for speeding things up enough to find long-dormant race conditions!

---

Addendum - IKEv2 does not have this problem because its equivalent to v1's Quick Mode is a simpler request/response exchange, so the responder is ready to receive when it sends the response back to the initiator.

NOTE: A version of this was sent to the racoon2-users alias also.

I've been spending some of my time bringing up racoon2 (an IKEv2 and IKEv1 daemon) on OpenSolaris.

Because of vast differences in PF_KEY implementations between OpenSolaris and other OS kernels, I've spent my racoon2 time actually getting IKEv1 to work first, instead of IKEv2. Right now, what's working is:

• IKEv1 initiates and derives IPsec SAs for single-algorithm IPsec policies.

That's it! IKEv1 responder needs work, as does all of IKEv2, as does work
for multiple-choice of algorithms. But there's enough change in there to say
something now.

ARCHITECTURAL DIFFERENCES

The most noteworthy change in the OpenSolaris work so far is that literally there's no spmd (a separate IPsec SPD daemon racoon2 uses) required for now. This is because:

• We don't have the indirection between ACQUIREs and the appropriate policy entry. Our extended ACQUIREs contain everything needed to construct a proposal. There's no SPD consultation required with an OpenSolaris ACQUIRE.
• Our responder-side logic uses inverse-ACQUIRE, which will provide the same structure as ACQUIRE w.r.t. proposal construction. This is the closest we get to needing something like spmd, and given its syntactic equality to an extended ACQUIRE, we can use it on rekeying if the responder initiates the next time.

If spmd serves another purpose, we will revisit it. As it stands, however, I cannot see us using it.

CODE DIFFERENCES

In OpenSolaris, we use the "webrev" tool to generate easy-to-review web pages with diffs of all varieties. The webrev for what I have so far in racoon2 is available at:

http://cr.opensolaris.org/~danmcd/racoon2-opensolaris/

Feel free to make comments or suggestions about what I've done.

My wife Wendy has had her iBook G4 for not-quite four years now. We had to return it once before via AppleCare due to thermal problems. Well, the thermal problems are back, and this time, there's no AppleCare for us to invoke. I managed to get the machine to behave itself only after leaving it powered off for a bit, but then it would lock again. I'd heard stories about putting computers in refrigerators to keep them cool enough to run. I never thought I'd try it myself.

We do, however, have a freezer in the basement. So check this out:



I managed to get Wendy's home-directory off, and that's what mattered. I'm heading off to the Apple Store to get a new MacBook (thank goodness for the just-arrived George-and-Nancy "Will you be my friend with this stimulus?" check). I hope to do the frozen data transfer one more time to bootstrap the new MacBook.

I'm not sure if this picture represents extreme stupidity in the protestor, or if it's merely a clever use of Photoshop to make a joke. If the latter, it's pretty funny. If the former... I have NO idea what to say.

Thanks to Fake Steve Jobs for bringing this to my attention.

BTW, for folks who need a quick history lesson - click here and follow your favorite search hit.

A little over a year ago, Bart Smaalders blogged about his new home server. Subsequently Bill built a similarly-configured one. (I thought that he had blogged about his too, but he hadn't.)

I'd been toying with the idea of following in Bill's and Bart's footsteps for some time. A recent influx allowed me to upgrade lots of home technology (including a new Penryn-powered MacBook Pro), and finally allowed me to build out what I like to think of as my home data center. I mention f''(Bart's...) because this box really is the second-derivative of Bart's original box (with Bill's being the first-derivative).

And the starting lineup for this box is:

• An AMD Opteron Model 185 - I was lucky enough to stumble across one of these. 2 cores of 2.6GHz AMD64 goodness.
• A Tyan S2866 - I bought the one with two Ethernet ports - one nVidia (nge) and one Broadcom (bge). It has audio too, but I haven't tested it as I've my Macs for such things. It has all of the goodies Bart mentioned, but I *think* that the SATA might be native now. (Please comment if you know.)
• 2GB ECC RAM - with room for two more if need be.
• A two-port old Intel Pro Ethernet 10/100 - good thing the driver (iprb) for this is now open-source. I'll explain why I need four Ethernet ports in a bit.
• Two Western Digitial "green" 750GB SATA drives Each drive has 32GB root partitions (yes that's large, until Indiana matures, though, I'll stick with UFS roots), 4 GB swap (for core dumps), and the remaining large areas combine to make one mirrored ZFS pool with ~700 decimal GB of storage.
• A cheap MSI nVidia 8400GS - It's more than enough to drive my 1920x1200 display.
• An overkill Antec 850W power supply - obtained for only $100 from the carcass of CompUSA.
• A Lian Li U60 case - My brother-in-law, who has years in the trenches of PC care, feeding, and repair, recommended Lian Li to me. It has all the space I need and more for drives, and its fan layout is pretty comprehensive. Since this box lives in my office, noise isn't that much of an issue.
• OpenSolaris build 83 - While I'm pumped about what's going on with Indiana it's still under development, and I want something a bit more stable.

So why four ethernet ports (covering three drivers)? Well, like Indiana, Crossbow is exciting, but not yet integrated into the main OpenSolaris tree. I do, however, very much like the idea of Virtual Network Machines and I'll be using these four ports to build three such machines on this server using prerequisite-to-Crossbow IP Instances. Two ports will form the router zone. The router will also be a firewall, and maybe an IPsec remote-access server too. With Tunnel Reform in place, I can let my or my wife's notebook Macs access our internal home network from any location. One port will be the public web server, and assuming Comcast doesn't screw things up too badly on their business-class install, the new home of www.kebe.com. The last port will be the internal-server and global-zone/administrative station. All of that ZFS space needs to be accessible from somewhere, right?

I'd like to thank Bart and Bill for the hardware inspiration, and to my friends in OpenSolaris networking for offering up something I can exploit immediately to create my three machines in one OpenSolaris install. I'll keep y'all informed about how things are going.

If the oddsmakers and pundits are to be believed, my two favorite NFL teams (my current-home Patriots and my childhood-home Packers) will be facing each other in a couple of weeks at the Super Bowl. Remember I said *if* the oddsmakers and pundits are right. If they are, I'm going to have to hide my Packers sweatshirt for the rest of January. And worse (well, worse for the football fan in me), I'm going to miss the game 'cause I'm on vacation with my family!

So what am I going to do? Simple: Root for Michigan!

Huh? Sure Dan - Michigan won their bowl game already... showing the SEC that not ALL Big Ten teams are pushovers, and sending Lloyd on with one more bowl win. What's this got to do with the NFL conference championships?

Well let's see here:

• Chargers - Well, nobody's perfect!
• Giants - Amani Toomer, who SI's Peter King calls, "one of the good guys... also one of the underrated guys.
• Packers - Michigan Heisman winner Charles Woodson (who I saw at the 1997 Rose Bowl). The last Heisman winner Michigan had also spent some of his late career with Green Bay... and Desmond Howard took home a Super Bowl ring!
• Patriots - Sitting on the bench at that 1997 Rose Bowl was a 6th round draft pick named Tom Brady.

No matter who you're rooting for this weekend, I've two words for you: GO BLUE!

Jun-Ichiro Hagino, better known to the IETF community as Itojun, died on October 29th at the age of 37.

Please visit this link for a message from his colleages at Japan's WIDE Project.

He led the KAME/WIDE IPv6 work that now appears in all of the BSDs (including MacOS X), and even their user-land tools are in Linux. Having worked on one of the pre-KAME IPv6 implementations (NRL), I can tell you that Itojun pushed things along even further than I'd hoped.

I had the privilege to talk with him when I was attending IETF meetings, and even visited him on his home turf in Tokyo. He was very unassuming, enthusiastic, and an all-around Good Guy (TM). I'll miss him, and a LOT of other people will too. PLEASE follow the link I mentioned above to see what you can do to honor Itojun.

Okay... I'm mad. I see that TiVo is offering another lifetime subscription transfer if you buy a new HD TiVo between now and the 8th of November. Pretty cool, huh?

Well, it's anything BUT cool if that lifetime subscription is on a DirecTV + TiVo box. TiVo's fine-print spells out quite clearly that: DirecTV DVR's with TiVo service not eligible for offer. I know TiVo and DirecTV get along about as well as Sun and NetApp (okay... maybe not THAT bad), but this leaves me, and I gotta believe some others, in the lurch.

I've determined I'm more TiVo-happy than DirecTV-happy. I've heard multiple-independent accounts that other DVR services and software leave a lot to be desired, especially if one had TiVo at one point. I've also continued to hear verification that the cable companies still suck, and my own recent experiences with the Cable Company have been less than stellar. I even started using Verizon for local phone service... something I swore I'd never do after then-Bell-Atlantic botched a simple two-phone-line installation so badly that I had to violate the network interface boundary to fix it.

So I see several opportunities for improvement, but I'm assuming any of the companies in question will bite. I doubt it'll happen, but if the Red Sox can win a second World Series in four years (GO SOX!), anything's possible.

Hey telcos --> pay attention, here's one geek's wishlist:

• Comcast - Start charging rates for two-cable-card HD setups that are competitive with DirecTV. You can get bonus points if I can get bundled discounts with business-class Internet service.
• Verizon - Stop holding the Mass. legislature hostage with a statewide TV franchise bill and keep rolling out more FiOS. I'd kill for 5MB upstream (lets me do more work), and I'd even pay for it. Throw in FiOS TV (which is supposed to have the bandwidth of DirecTV with the bundling/saving opportunities of cable) and I might be all over it. I told your phone reps that if they do well, they'd get more of my monthly subscription money!
• DirecTV - Get over yourself and re-partner with TiVO. I hear that if John Malone gets a large interest that such a re-partnering may very well happen. Throw in the $200 lifetime subscription upgrade fee, and I'll keep facing South-Southwest!
• TiVo - Unless one of the above miracles happens, please consider a migration path for DirecTV Tivo users? I've a bad feeling one of your divorce terms was to not poach from the DirecTV subscriber base. If so, that's too bad, because I'll bet there are a lot of people who want to keep TiVo more than DirecTV.

Any takers? (I somehow doubt it, but a guy can hope...)

Oh my am I exhausted! I hoped to have most of the text of this completed before my flight got back to Manchester last night, but that didn't happen.

I keep telling people I know that Michigan is a hardware school (in spite of having some great software people - see my post from Monday). We Solaris developers at the Sun table were brutally reminded of this yesterday. Lots of EE's with Verilog and/or VHDL experience. Many of them asking about architecture and/or verification, but a surprising number who have never heard of SPARC, the UltraSPARC T1 (aka. Niagara), or that they can see the entire source for the Niagara with OpenSPARC. Almost every business card of mine I handed out to folks had the word, "OpenSPARC" on the back so they could Google it later.

We also tried to make sure everyone had OpenSolaris disks. There are four binary distributions of OpenSolaris on that set of disks: Solaris Express Community Edition (see the previous link) - Sun's current OpenSolaris vehicle, Nexenta - which is probably going to be one of the more comfortable ones for Ubuntu Linux users to land in, Belenix - which is optimized for Live CD use, and Schillix, which was the first non-Sun distribution of OpenSolaris, by Joerg Schilling of "cdrecord" fame. I hope some of the students went home and had success playing with OpenSolaris. You all should visit opensolaris.org and engage the community discussions with your feedback and questions.

I mentioned Monday about how much like a geezer I felt. I had more of that yesterday not only saying, "Class of '91" a few times, but also when Professor Quentin Stout visited our table. My only graduate-level class I took at U. of M. was his Parallel Algorithms class in the fall of 1990 (during Football/Marching Band season). Back in the day it was all theory - we discussed how to partition problems using the abstract PRAM (Parallel Random Access Machine). It was the ONLY parallel ANYTHING class offered when I had an available slot. This was when shared-memory multiprocessors were experiments or startups (anyone remember the BBN Butterfly, the Sequent Balance, or the Encore Multimax?). I mentioned to Prof. Stout I took his class back then. He then proceeded to tell me how the class is far more practical now. He told me all about stuff like OpenMP, and other high-level constructs that as a systems' programmer I just don't get to use all that much. I still, however, felt pretty smart for seeing the future back in 1990. I hope I have as good luck 17 years later.

Anyway, I had a great time in Ann Arbor, and I hope to get back there sooner rather than later. If anyone who visited our table is reading this, leave a comment, and don't be afraid to be honest. :)

I mentioned I was going to be at the University of Michigan's Engineering career fair, and here I am!

I got in yesterday (Sunday) afternoon, and did some things to re-orient myself. I visited my fraternity house first, and quickly, because rush began that night. In some ways things hadn't changed a bit - the house is still there and the rooms have the same names (my old room with a skylight window is still called Lighthouse). In other ways, they had - the TV is bigger and flatter, half of 'em had laptops, and the basement was being seriously renovated. The guys were pretty mellow, probably because of all of the post-beating-of-Penn-State celebrations. I then wandered around campus, eating dinner at Krazy Jim's Blimpyburger, where they give you burgers made of small, ground-that-day, patties. Yum!

When I flew in, the woman next to me on the plane explained the phenomenon she experienced when taking one of her kids to her alma mater. It all felt intimately familiar to her, even modulo some new buildings, but then she suddenly realized she was an old fart wandering campus. My kids aren't old enough to be shopping colleges yet, but I definitely felt the combination of familiarity and age. I saw buildings with new names, old names on new buildings, and just plain new buildings (esp. at North Campus). 20 years ago I was a freshman, now I'm literally old enough to be a father to a student in the incoming class of 2011.

This morning, I tagged along with Kais Belgaied as he visted some Computer Science faculty and grad students here. Our first visit was with Professor Z. Morley Mao, who's a new professor here. She has a lot of great ideas on how to exploit the Crossbow project for aiding intrusion detection (and mitigation), among other interesting ideas. We then talked to two other professors, Atul Prakash and Thomas Wenisch, and a few students as well. I remember Prof. Prakash from my time at Michigan (1987-1991), but the other two are new Assistant Professors. I'm confident from what I saw that U. of M.'s CSE division of EECS is going to be strong for a continuing number of years.

[Edit from Wednesday]Shoot! I forgot I also visited my old theory professor, Kevin Compton. He's a very good teacher, and helps even the most clueless undergrads (hem hem). He told me he's teaching a very popular undergraduate cryptography class, which is just too-cool, IMHO.

This evening several of us (Kais, Eric Kustarz, Bill and Sherry Moore, and I) gave a breezy tech talk about various goodies in OpenSolaris that we work on. We also had very yummy Pizza House pizza. Pizza House was "established 1986", which means it wasn't all that old when I was there, but it was good enough to have our host recommend it.

I'm now back in my hotel, squeezing packets over a flaky, but free, wifi. Tomorrow we will be spending the whole day at the table, taking resumes and answering questions. If one of you four readers of this blog is a U. of M. student, you don't have to wear a suit when visiting us. :)