Muli Ben-Yehuda's journal

August Penguin 2004 happened on Friday morning, and was a blast. My
august-2.6.8-rc2bk8-E1
patch which was used in the hacking competition is available on the kernel page.

This is august-2.6.8-rc2bk8-F1,
a small patch I wrote for the August Penguing 2004
Linux convention hacking
contest. The contest had several stages. In each stage,
the contestants needed to perform a task. For stage 3, the
task was to change a file named ‘stage3.tmp’. The obstacle in
their way was this patch.

The patch has two parts: the first is a Linux Security
Module named “august.c”, which protects this file from
unwanted access via the LSM hooks. It also has a small
backdoor – it only works if the date is after the beginning
of August 2004. Contestans were expected to find the patch
(we left the sources on the machines), discern the backdoor,
change the date, and win. Version -E1, which was used in the
competition, also had some interesting “side effects” like
zeroing the file whenever it was accessed.

In order to prevent the contestants from booting with a
non-modifed kernel and changing the file there, we put the
file on a loopback mounted minix file system. This minix
file system had a non standard magic number in its
superblock, which means that only a kernel that had a patch
to its minix fs code to recognize our minix magic number
would agree to mount it. This is the second part of the
patch.

(prev: -A1,
-B1,
-C1,
-D1,
-E1)

Tomorrow is the annual Israeli Linux Conference, August Penguin (Hebrew) . I am one of the organizers, taking care of the PGP Key Signing (Hebrew). I am also helping with the Hacking Contest (Hebrew). This is “Hacking” in the good sense of the word – each team of contestants starts with a Linux machine we set up earlier, the root password, and a mission. To accomplish the mission, they must show intimate familiarity with what makes a Linux system tick, and be able to think and code under pressure.

Last weekend, I spent a couple of pleasant Tucson evenings writing a kernel patch that will make the contestants lives a little bit more interesting. I thought I had it working, but today Aviram Jenik and the BeyondSecurity team put it on the machines, and we discovered that it’s not working quite as it’s supposed to. Which is why I’m now sitting at 2 AM at the office, writing this. I had a working but non-optimal patch around 11 PM (-E1), and a working nearly-optimal one at 1 AM (-F1).

We’ll be using the -E1 patch tomorrow, since it’s already on the machines, works (I sure as hell hope so) and we don’t have enough time to test -F1. I’ll post the patches here after the party, along with explanations and the success (or failure ;-)) stories.

I made it back home.

I woke up at 5 AM at Tucson, packed my suitcase (everything fitted – barely – but it bulges ominously), had some breakfast, and left for the airport before 7. My flight was around 10, if I recall correctly. Made it through ticketing, security etc in 20 minutes, and had 2 and half hours to wait for the flight.

The Tucson->Atlanta flight was fine, nothing special. When I got to Atlanta, I had a few hours to kill before the next flight, which was supposed to leave at 7 PM. I sat the gate area, read my book, and waited, and waited, and waited. Around 6:30 PM, the flight attendant had a nasty surprise for us. “The flight will be delayed until 8:30 PM. Please wait by the gate area for further instructions”. Oh fuck, thinks I, I have a midnight flight to catch from New York to Israel. Let’s talk to them and see if there’s anything that can be done. Turns out that every other flight to NY is full. If I’m going to be stranded, I’d rather be stranded in NY, one leg closer to home.

Our flight did not leave Atlanta until almost 10 PM, a 3 hour delay. I knew that making the flight in NY wasn’t going to happen, and wondered what I’d do. When we got to NY, at almost 1 AM at night, the Delta representative booked me on the next flight to Israel, at 10 AM in the morning, told me that my luggage was now El Al’s responsibility, and apologized for the delay (like that ever helped anyone). The also claimed that since it was due to the weather, they can’t provide a hotel for the night or any other compensation. $SWEAR_WORDS.

I tried to find the El Al folks, but they had already gone home. I briefly considered spending the night at JFK, but decided against it. It was cold, there were Persons of Dubious Quality aroundand and I sorely needed a shower. I took the last room that was to be had at the JFK Radisson, a miserable, expensive hotel. Hit the bed at 2:30 AM. I had no suitcase, and although I always take an extra pair of tshirt and underwear in my carry on baggage, naturally, this time I didn’t.

Woke up at 5:30 AM, dressed, went hunting for some way of sending email (found one, but damn, it was expensive), and was back at JFK by 6:30 AM, looking forward to getting on the flight, preferably with my suitcase. The El Al people were nice, courteous and professional. Much appreciated after my Delta experiences of last night. I don’t think I’ll be flying Delta again in the near future.

I made it through security, etc, with no problems, and by 7 AM I was at the gate area. Great, another 3 hour wait at the gate… With regards to the suitcase, the El Al people said the suitcase will be on this flight or the next one, which was good enough for me. Had some breakfast, and bought the new Tom Clancy book, since the myriad delays of yesterday caused me to finish the new Stephenson book earlier than planned (it’s very good, far more “Cryptonomicon” than “Quicksilver”).

Boarded the flight at 9:30 AM. The person at the gate confirmed that my suitcase has boarded as well. Finally, something is going right!

The flight was long and tedious. I hate flying in general, but trans-atlantic flights are far worse than usual. Small, cramped seats (next time, fly me first class, IBM!), bad food, etc, etc. At least the movies were reasonable – watched Shrek 2 (cute), Mean Girls (pretty people, stupid movie) and Walking Tall, which I liked a lot. Had a few conversations with my seat-mates, a young Jewish couple. The Clancy book, btw, sucks. Not as badly as Rainbow Six, but I doubt I would’ve finished it if I weren’t stuck on an airplane.

Landed at 03:30 AM. It’s good to be back in .il, where it’s all insane, but it’s *familiar* insanity. Made it through immigration quickly, waited for 30 minutes for my suitcase, and then got it. Ripped open. Looks like it burst at the seams. Briefly debated trying to figure out if anything is missing, and then decided that it can wait for home. Found my IBM-arranged ride (Thanks Orna and Oleg!) and left for the final leg of this long journey.

Made it home at 5 something AM. Woke Orna up. It’s good to be home.

(Nothing is missing from the suitcase, as far as I can see. Thank $DEITY for small miracles).

Once OLS was over, Orna flew home and I flew to Tucson, for a week of exciting (not!) work at the IBM facility here. Thankfully, it’s now Saturday night, the week is over, and tomorrow I fly home.

The week passed fairly quickly, breakfast -> work -> dinner -> sleep. I missed Orna terribly. Today we had a day off, and I went shopping. I hope my poor suitcase will not burst at the seams.

This was actually my first business trip, if you don’t count OLS last year. I think I can safely say that once is enough.

I started writing a few words about each talk we went to, but decided that since my memory sucks and my notes are intelligible, I’ll just talk about some of the great moments. ladypine and me will be giving talks at Haifux, Telux and our respective work places on the more interesting talks we went to, and will post our notes and slides online once we type them up.

The best thing about this OLS for me, I think, was that I overcame my shyness and actually talked to people. I talked to lots and lots of folks, going as far as skipping some talks to sit outside and talk to people.

The worst thing about this OLS was the network. No net access in our hotel room (one wireless network visible while sitting on the bottom right end of the bed, but no access to it), spotty wireless in the conference halls, and it took me a couple of days to get over the network-withdrawal.

The best talk I heard was James Bottomley’s Unmapping the Page Cache talk, which was mindblowing. In short, no pages except those actually in use are mapped into the kernel’s virtual address space. I will be taking a good look at the paper and implementation (if it’s available?), as it’s just such a cool hack.

The worst talk shall not be disclosed here (no reason to insult the speakers, I’m sure everyone did their best), but there were several talks where the time could’ve been better spent just reading the paper.

The best BOF was without a doubt the impromptu virtualization BOF at the Elephant and Castle Pub. Very interesting discussion on what Linux could do to support virtualization better, with people from IBM, VMWare, Xen, coLinux and others.

Best party was the party the Black Thorn. Unlike last year, I sat and talked with people all evening long. I also had 3 beers, which is quite a lot for me. I wonder if there’s a correlation…

Worst party was probably the LinuxChix BOF, which was fun in and off itself, but took place in a HOT, LOUD milkshake-bar. I would’ve said the opening night reception (which everyone told us sucked…) but we missed that.

Most “interesting” moment was the CAPP/EAL3 talk, where I discovered that SUSE reimplemented large parts of syscalltrack for their kernel audit mechanism. Even though I haven’t worked on syscalltrack in a long time, hearing this was not pleasant. I can’t help thinking that maybe if we’d have done things differently, syscalltrack in some incarnation would be in the vanilla kernel now…

In summary – OLS 2004 rocked hard. I’m sure 2005 will rock just as hard, and we’ll be there.

On Tuesday, we woke up far too early. We were at the airport at 6 AM
or some such, three hours before our flight. As could be expected, we
made it to the gate area in 20 minutes, and then spent a few hours
waiting for our flight. The flight was uneventful, half business
people, half OLS folks. It was pretty easy to tell who belongs to what
group – both groups had distinct dress codes. We met Orran Krieger,
whose work I’ve been admiring for a long time (even since I’ve heard
of K42, to be specific).

At Ottawa we checked in to Les Suites, and went out to buy some food
for the up coming week. We met Gilad, Limor and Dan Aloni, and went
for a walk on the river with them. In the evening we all had Mexican
for dinner at the Mexican restaurant I remembered so fondly from last
year. I got a birthday penguin, too!

Tomorrow – OLS begins!

Monday, our last day in Boston. The first thing we noticed as we
stepped out of the hotel was the weather. Clouds, occasional drizzle,
relatively cold – this is what Boston weather should look like! Not
those hot sunny summer days we’ve had since we’ve got here.

We started the morning at “Filene’s Basement”, a Boston
institute. Orna bought tons of dresses, and even got one for
free. We spent a long time there, and I slowly lost my mind as Orna
tried on dress after dress after dress. But hey, whatever makes my
sweetie happy!

From Filene’s Basemen we went to another Boston institution, the
Brattle Bookshop, where we bought lots and lots of goodies. I don’t
remember what Orna bought, but I bought Feynman’s QED
and Flags
of Our Fathers.

Then we went looking for FAO Schwartz, the famous bear and toy
store. We found the bear, but the store has apparently closed down
some time ago. Orna was not pleased.

We had lunch at a pretty nice place that serves salads, soups and
ready made sandwiches among a business crowd. Then we went to see
Trinity Church’s glass windows, but it was closed for renovations.

We headed back to the hotel to get rid of the books we were carrying,
and then when on a book shop tour of Cambridge’s book shops.

First, I wanted to see if we could find the FSF’s offices. Turns out
that it wasn’t far from our hotel. We went there, and couldn’t find
it. When we got back to the hotel, I checked and it turned out that
the FSF is located at a street with the same name – in Boston, not
Cambridge.

First we went to Quantum Books, where I bought Minsky’s Society of
the Mind and Neal Stephenson’s latest, The
Confusion. Then we went to the MIT Coop, where I really lost it. I
bought Gray’s Anatomy,
Feynman’s Lectures
on Physics, Stephen King’s newest, Song
of Susannah, and probably some others I can’t recall right now. It
was insane. It was great.

From the MIT Coop, we headed toward the Charles river, and eventually
made it to the place that was arguably the main reason we came to
Boston – the Massachusetts Institute of Technology, cradle of
hackerdom.

We walked around MIT a bit, taking in the atmosphere, and then went to
visit Hart’s Nautical Gallery.

On the way to the hotel, we passed by the MIT Museum that was
unfortunately closed. We weren’t too disappointed – together with the
Boston Tea Party Ship, they provide ample reasons to visit Boston
again one day 😉

Dinner was had at Sidney’s, the Hotel@MIT restaurant, which was
great. Afterward, we discovered we had a drugstore inside the hotel,
did some necessary shopping, and went to sleep. Tomorrow – OLS!

The plan for Sunday was to visit the Boston Common and walk the
freedom trail. I had a hard time waking up, and by the time we got to
the Boston Common, I was feeling all queasy (possibly due to the
greasy breakfast we had at McDonalds). I sat on a bench near the duck
pond, and Orna went a-strollin’ in the Common’s gardens, taking
pictures of … what else, squirrels. And birds, ducklings, peaceful
mulices, etc, etc.

When Orna returned from her duck photographing escapades in the Boston
Common, we considered canceling our plans and heading home. I wasn’t
feeling up to doing anything, and Orna caught my bug and wasn’t up to
doing anything either. I realized that a) Orna will not go on without
me and b) she will be really miserable if we go back to the hotel, and
forced myself to get up and start walking. Amazingly enough, it
worked. We walked along the freedom trail, saw Boston’s many burial
grounds (I still find it peculiar that a burial ground is a tourist
attraction, but … ok), and visited Paul Revere’s house. Actually, we
just passed by it, didn’t even go inside. I just wanted to sit and
rest, and Orna was annoyed that photographing inside is not alowed. We
also saw a strange parade in the Italian quarter.

The freedom trail ends at the Charlestown navy yards. I wanted to find
lunch (just an excuse to stop walking, really), but we didn’t find
anything appetizing, and so went on and visited the USS constitution,
the oldest ship still in commision in the US Navy.

From the navy yards, we walked a loooong time until we found a T
station, took the T back to Cambridge, wolfed down lunch/dinner at a
Burger King (hey, it was there and it was open), made it back to the
hotel, and collapsed on the bed. We made it.

In the morning of day 3, we went a-walking to Harvard Yard and Harvard
Square, in Cambridge. We had dinner sitting on the grass, and then
Orna took many pictures of squirrels. Many, many pictures of
squirrels.

Cambridge is so quiet on Saturday morning, everything is peaceful and
serene. Once again I mention to Orna I would love to move here, and
once again Orna says something about 20 degrees below.

From Harvard Square, we went to the Harvard Museum of Natural
History. This is the “real thing”, with exhibits that scientists use
to study animals and plants. The halls are quiet, and have a dusty
feeling to them.

[Orna writes: ] Muli particularly liked the glass flowers exhibit,
since it had very strong air conditioning. He sat down on the floor
and studied the documentation for his new watch (a swatch with many
dials and hands, that stops moving when you press a button, but then
another hand starts moving…). Orna was suitably impressed with the
glass work, which was so good she had to convince herself that it’s
actually made from glass.

We saw a fish with hands and legs, sitting in a box full of
formaline. This is the 41st fish of its kind that was caught, out of
about a hundred. Did the first one that was caught survive? The fish
was located among many dinosaur skeletons. The next hall as the
stuffed animals hall, each room more fascinating than the previous
one, so I kept taking pictures. Muli gave up around the birds stage,
but Orna kept going to the crystals and precious gems exhibition,
where she got a demonstration of a technique to tell crystals apart:
based on their respone to UV light, based on the color that they leave
as a powder, and based on their reaction to acid.

Muli tried to convince Orna that if they’ll live in Boston one day,
they’ll be able to take the kids here every day. Orna reminded him
about the cold again.

We then went to the Boston Science Museum, not according to the
original plan (we meant to head for the MIT museum), due to a pretty
prosaic reason – it was closer to the T station. Yes, the value of
things began to be measured in “standing on our feet” quotas. Is it
worth walking there? is it worth standing and looking at it?

The science museum was disappointing. Flooded with violent kids,
unmaintained exhibits (broken, not working, giving a Windows error
message on the screen!). Many exhibits are dedicated to the same
subject, none of which require real action or thought on the part of
the viewer.

The computer museum, which is the real reason we visited the science
museum, has been dismantled. Its exhibits have been divided among 6
different museums, and there were only a few exhibits on display at
the science museum. Muli really liked them; Orna was disappointed by a
simulation enigma machine that didn’t quite work.

The next attraction was the duck tour. A ride in an amphibean
vehicle. There are 22 duck tour vehicles, and the drivers have created
their own folklore. Our driver, in particular, enjoyed breaking some
long-held Boston myths – the only reason Paul Revere is so famous, for
example, is because he was caught on the midnight ride. There’s
another guy who actually completed the ride without getting caught,
but who ever heard of him…

Sailing the river in the amphibean vehicle, Orna took pictures of
cormorans, seagulls, and maybe even a duckling.

After taking the T back to Cambridge, Orna stayed behind to buy shoes,
and sent Muli alone to the hotel. Ten minutes later, he returned. It
turned out he walked in the opposite direction.

Paul McKenney‘s Linux Kernel Scalability: Using the Right Tool for the Job.

Linux Kernel Networking Summit presentations, especially the summary and the 2.7 plans.