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Understanding Mac OS X Kernel

Posted by timothy on from the deep-in-the-heart-of-it dept.

An anonymous reader writes "Kernelthread.com has published a flash presentation overview of the Mac OS X kernel. Its title is 'A Tour of the Mac OS X Kernel' and it also covers Tiger features. Maybe interesting to note is that the slides are from a talk given to the NSA. Well, there is a nice security architecture diagram towards the end of the presentation."

57 comments

  1. AES encryption under the hood? by neuro.slug · · Score: -1

    Correct me if I'm wrong (and I may very well be, as it's been over a year since I took cryptography), but isn't AES somewhat flawed? What are the reasons that it's used for page and FS encryption?

    -- n

    1. Re:AES encryption under the hood? by zhiwenchong · · Score: 4, Informative

      Apparently not:
      http://en.wikipedia.org/wiki/AES#Security

    2. Re:AES encryption under the hood? by Anonymous Coward · · Score: 1, Informative

      You're wrong.

      Maybe you're thinking of the old DES standard.

      http://en.wikipedia.org/wiki/Data_Encryption_Stand ard

    3. Re:AES encryption under the hood? by Anonymous Coward · · Score: 3, Informative

      FS and swap encryption is used to encrypt user's home directories. This is the "File Vault" functionality of OS X. Tiger adds the ability to optionally encrypt the users swap space also (only on file vaulted home folders) to secure the users memory space as well. A file vaulted home folder becomes a sparse disk image file (a disk image that can grow in size as it's written too) that uses the users account password to open. If the user losses their account password then the admin can use the master file vault (set separately) to restore the users home directory. That scenario only really applies for multi-user systems.

      I am not sure what bit of AES is used though. I would guess 128 bit at least.

  2. amazing! by Anonymous Coward · · Score: 3, Funny

    A flash presentation that didn't turn my p4 into a 386!

    1. Re:amazing! by brilinux · · Score: 5, Funny


      What, did it turn it into a G5?

    2. Re:amazing! by Anonymous Coward · · Score: 0

      Didn't you see Apple's announcement last month? G5s will now be turning into P4s!

  3. inside the kernel by Anonymous Coward · · Score: 5, Funny

    Does it give away the kernel's secret recipe?

    1. Re:inside the kernel by commodoresloat · · Score: 2, Funny

      Mmmm, kernel pancake....

    2. Re:inside the kernel by green+pizza · · Score: 2, Insightful

      kernel's secret recipie
      You don't need 11 herbs and spices, that's for sure. "Seasoned Oven Fried Chicken" spiced with cheap McCormick Season-All Seasoned Salt from your local grocery store will give you almost the same flavor. As an added bonus, you can control exactly how much or how little grease you want! Take that, KFC!

    3. Re:inside the kernel by Anonymous Coward · · Score: 0

      I recall seeing those pesky Indians (on TV) rioting in the streets of some ghetto (could have been anywhere there..lol) chanting "Just the chips not the chicks" upon learning of the secret ingredients in KFC's recipie (which was a requirement of being granted a license to open fast food restaurants across India). One of their public officials being interviewed indicated that they were going to ban some of those ingredients and also levy taxes on sugar water producers (at the time, KFC was owned by Pepsi) because, if there is "easy money" in India to be made, it is to be made only by Indian companies. Anyway, appologies to all of the young /. nerds going blind chanting "just the chips not the chicks" --the origin of the expression did not come from Tomb Hunter, but from hords of swetty sheet-wearing peasants looting and rioting infront of yet-to-be-opened KFC-India restaraunts.

      For the GenX (and BabyBoomer) peeps among us...Before going down there (particularly you former M$ employees) and setting up your underwater cities (that economically capture

    4. Re:inside the kernel by Anonymous Coward · · Score: 0

      I recall seeing those pesky Indians (on TV) rioting in the streets of some ghetto (could have been anywhere there..lol) chanting "Just the chips not the chicks" upon learning of the secret ingredients in KFC's recipie (which was a requirement of being granted a license to open fast food restaurants across India). One of their public officials being interviewed indicated that they were going to ban some of those ingredients and also levy taxes on sugar water producers (at the time, KFC was owned by Pepsi) because, if there is "easy money" in India to be made, it is to be made only by Indian companies. Anyway, appologies to all of the young /. nerds going blind chanting "just the chips not the chicks" --the origin of the expression did not come from Tomb Hunter, but from hords of swetty sheet-wearing peasants looting and rioting infront of yet-to-be-opened KFC-India restaraunts.

      For the GenX (and BabyBoomer) peeps among us...Before going down there and setting up James Bondesq underwater cities (to economically capture $10K/yr coders en masse) --make sure that you read the post-1930 history of that country (much of it in newspapers and television form only!), or at least listen to the lyrics of The Police's "Wrapped Around Your Finger" about 50 times. (Your head will actually explode if you listen to Sting outside of the setting of a PBS fundraiser, but once upon a time, Sting was young and knew real live Jobs-like geniuses and they were known as The Police.) When the time comes, those Indians will do alot more than rise up and throw their boots into the machines.... But first they will have to get everyone hooked on their services (and slowly wait for the non-Indians among us who can still handle low-level languages an assemblers to die a punishing capitalistic death). In the end, the Game coders (who breath low level languages and assembly) may be our only salvation, especially when Moore's Law hits the wall (along with chip speeds) and the (relatively) young Perl, Cocoa and .Net ("ADD software tools") rediscover what life was like for programmers in the late 70s and 80s.

  4. Eek, a presentation in flash! by Psychic+Burrito · · Score: 2, Informative

    There is no way to step back (at least I found none), to get an overview, to jump to a certain frame (like the mentioned security architecture diagram) - why do people make presentations in flash, instead of pdf or css (example)?

    1. Re:Eek, a presentation in flash! by Anonymous Coward · · Score: 0

      Running the flash presentation reminded me of the song from The Firm called Star Trekkin

      The chorus goes like so:
      Star Trekking, across the universe,
      On the Starship Enterprise, under Captain Kirk.
      Star Trekking, across the universe,
      Boldly going forward, 'cause we can't find reverse.

    2. Re:Eek, a presentation in flash! by macshome · · Score: 1

      Erm, right click > Back seemed to work for me.

  5. Keynote by TimmyDee · · Score: 4, Informative

    I'm willing to bet it's in Flash because he did the presentation in Keynote. While the SWF export in Keynote isn't great, at least it preserves transitions, fonts, and other formatting options and doesn't look like shit (like the HTML export of another presentation software).

    Plus, it takes one step to export. I haven't seen anything that will do that with CSS.

    --
    Per Square Mile, a blog about density
    1. Re:Keynote by Val314 · · Score: 1

      PDF would be a better choice...

  6. Worthless filesystems. by Given+M.+Sur · · Score: 4, Funny

    So HFS+ can only support file sizes up to 8 exabytes. What a worthless filesystem.

    --
    nil
    1. Re:Worthless filesystems. by Chucker23N · · Score: 4, Funny

      And here I was, hoping HFS+ would provide the means to fit all my pr0n on it.

    2. Re:Worthless filesystems. by Anonymous Coward · · Score: 1, Insightful

      You must be one hell of a pornophile if your files are larger than 8,589,934,592 GB.

    3. Re:Worthless filesystems. by Chucker23N · · Score: 1

      I have desires and wishes to be satisfied.

  7. NSA deciding how to break into Mac computers? by Futurepower(R) · · Score: -1, Offtopic


    From the Slashdot article: "... the slides are from a talk given to the NSA."

    The probably reason that NSA staffers are interested in this subject is to decide how to break into Mac computers. The NSA and other U.S. government organizations are the most well-funded spy organizations in the world, by far.

    The NSA is an interesting U.S. government organization. Most U.S. government organizations are expected to follow the law, but the NSA and many other secret agencies are allowed to break U.S. laws and the laws of other countries. This attracts a lot of people who like to engage in that kind of behavior.

    U.S. citizens are expected to pay for everything, but they are not allowed to know how much they pay, or even know the names of some of the law-breaking agencies, or what the agencies are doing.

    "Blowback" is a U.S. government spy agency term for the negative results of the U.S. governments secret hostile attacks on other countries. The bombing of the World Trade Center was blowback from the U.S. government's largely secret support for killing Arabs. (The U.S. government had various justifications for the killing.) It is not a surprise that Arabs don't like to be killed. It is not a surprise that some Arabs would decide to return hostility with more hostility.

    Secrecy is incompatible with democratic government.

    1. Re:NSA deciding how to break into Mac computers? by noewun · · Score: 2, Informative

      Sorry to dint your tinfoil body suit, but the reason the NSA is interested in OS X is because they use OS X. I have a very interesting, very thorough PDF authored by the NSA (report #I331-009R-2004) on how to secure an OS X box, from install through end use. Very interesting, and I learned a bit.

      --
      I am a believer of momentum and curves.
    2. Re:NSA deciding how to break into Mac computers? by wirelessbuzzers · · Score: 2, Informative

      The NSA is not allowed to break US laws. Of course, they spy on other countries, so they're probably allowed to break other countries' laws.

      As for the other nasty stuff, it sounds an awful lot like your tinfoil hat is on too tight.

      Also, if you want to hack a computer, you probably care more about the services running on it than the guts of the kernel, at least up to the point where you install a rootkit. They probably care more because they want to use MacOS X in a highly secure environment. SEDarwin anyone?

      --
      I hereby place the above post in the public domain.
    3. Re:NSA deciding how to break into Mac computers? by Anonymous Coward · · Score: 0
      The mentioned NSA security guides for various OS's, routers, and network kit are available here.

      I've used the NSA guide for Cisco IOS extensively, and have looked through the Mac OS X one. It's a great running start to securing a new box. But like any security process, you can't stop there.

  8. Architecture slide by Anonymous Coward · · Score: 0

    If you look closely, the slide with the Architecture (3 or 4 in) has more info. in that black block. It's hard to see though.

  9. For explanatory purposes by Anonymous Coward · · Score: 1, Informative
    "Largest file size is 2^63 bytes"

    Pedantic note:
    • 2^63 bytes == 9007199254740992 KiB
    • 9007199254740992 KiB == 8796093022208 MB
    • 8796093022208 MB == 8589934592 GB
    • 8 exabytes == 8*(1,024*1,024*1,024) GB == 8*1073741824 GB == 8589934592 GB


    ____

    Now my head hurts
  10. Ctrl-Click or Right Click by josephtd · · Score: 1

    Gives you a popup when done in cinjuntgion with mouse over the presentation. At least it does in Safari.

    1. Re:Ctrl-Click or Right Click by rthille · · Score: 1

      Yeah, I tried that. But selecting 'Back' from the resulting menu had no effect. (10.3.9, Safari 1.3 v312)

      --
      Awesome furniture, accessories and cabinetry in Santa Rosa, CA: http://humanity-home.com/
  11. I wish it was PDF by green+pizza · · Score: 1

    I'm willing to bet it's in Flash because he did the presentation in Keynote.
    Too bad he didn't export it to PDF. Keynote 2 (the version that ships in iWork 05) has an excellent PDF exporter.

    1. Re:I wish it was PDF by jeblucas · · Score: 1
      Please read what OP said:
      While the SWF export in Keynote isn't great, at least it preserves transitions, fonts, and other formatting options...
      That's a fancy PDF that preserves transitions.
      --
      blarg.
  12. So, HFS+ can be case-sensitive... by rthille · · Score: 0, Flamebait

    How the hell do I turn that on. Case preserving sucks ass when interacting with case-sensitive system...
    Use FTP to mount a remote webserver. Attempt to copy all the files to a local directory for modification. Finder complains 'some files differ in case and only one will be copied. Continue?" Would it be that fucking hard to list the files that conflict and give me the option to rename them? Jeeze.

    --
    Awesome furniture, accessories and cabinetry in Santa Rosa, CA: http://humanity-home.com/
    1. Re:So, HFS+ can be case-sensitive... by ahknight · · Score: 3, Informative

      Like this: http://www.codepoetry.net/archives/2003/10/26/case sensitive_hfs_for_the_masses.php

    2. Re:So, HFS+ can be case-sensitive... by macshome · · Score: 2, Informative

      Just use diskutil on 10.3 or Disk Utility in the GUI on 10.4. Josh

    3. Re:So, HFS+ can be case-sensitive... by Anonymous Coward · · Score: 0

      You cannot turn a partition from case preserving to case sensitive without erasing it first. One way to do it is at a fresh OSX install: repartition and select HFS+ case sensitive.
      Take care when you'll make the root partition case sensitive (even though you can and OSX will work on that): it will make it harder for you to install Warcraft III, Adobe Creative Suite and maybe other applications. I have a root HFS+ partition, and I had to create disk images for both apps.
      The best way would be to have a case-preserving root filesystem and create a sparse disk images in the HFS+ (case-sensitive) format.

  13. Embedd C++ by bhima · · Score: 1

    I find it interesting that parts of the Kernel were written in Embedded C++. I haven't had the opportunity to use this although I'd love too. Anyone have an experience with EC++ they'd like to share?

    --
    Nothing in the world is more dangerous than sincere ignorance and conscientious stupidity.
    1. Re:Embedd C++ by Nuuskis · · Score: 4, Interesting

      Embedded C++ is upwards compatible subset of ANSI Standard C++. So if you have written very simple C++, for example when coming from C and making your first C++ program, you probably "used" EC++. It is just C++ without namespaces, templates, exceptions, RTTI (Runtime Type Identification), STL (Standard Template Library), and some other stuff that might make executable noticeably bigger and cause unwanted memory consumption.

  14. * Encrypted swap (optional, uses AES) by VValdo · · Score: 1

    Wow.. So it looks like they finally fixed this security bug where the password could be discovered in the swap. Anyone know how to turn this feature on? (don't have Tiger yet & a quick Google search turns up nothing)

    In the same vein, I recall OS X versions up to jaguar had weakly-hashed user passwords in a SAMBA directory somewhere. If I'm remembering correctly, can someone verify that this is no longer the case in Tiger?

    W

    --
    -------------------
    This is my SIG. There are many like it, but this one is mine.
    1. Re:* Encrypted swap (optional, uses AES) by kerry-buckley · · Score: 5, Informative
      Wow.. So it looks like they finally fixed this security bug where the password could be discovered in the swap. Anyone know how to turn this feature on?
      There's a "use secure virtual memory" checkbox in the security preference pane.
    2. Re:* Encrypted swap (optional, uses AES) by 68kmac · · Score: 2, Insightful

      It's an option in the "Security" panel of the System Preferences.

    3. Re:* Encrypted swap (optional, uses AES) by macshome · · Score: 1

      You turn on encrypted swap in the Security prefs. I know of some people doing netboot with encrypted local swap for security.

      Hashing is now selective again. If you don't need SMB access for an account it won't make the NTLM hash.

  15. What's The Point? by Anonymous Coward · · Score: -1, Flamebait

    Over the next two years Apple's installed base is going to shrink and their margins are going to have to drop dramatically.

    All that money from the high margin hardware and the now slowing iPod sales are going to increasingly slow the OS development to the point where it is unlikely Apple will be able to continue their OS development.

    Of course there are still diehard Apple fans who are clinging to the fantasy that being forced to use Intel chips is going lead to cheap and fast Macs, but the writing is on the wall for OS X as we know it. Funding OS development is insanely expensive and Apple is going to lose the ability to continue it over the next couple of years.

    Some sort of partnership with Microsoft? And Apple layer on top of Linux? Dump everything but the iPod/iTMS stuff? Whatever it turns out to be, OS X as we currently know it has as much of a future as Apple now obsolete PPC based Macs. The OS X kernel is soon to be something of historical interest only.

    It's too bad Steve wouldn't cough up the cash for a mobile chip design from IBM, Apple is rolling in cash these days. Penny wise, pound foolish.

  16. Re:So, HFS+ can be case-sensitive... / shure! by Anonymous Coward · · Score: 0

    what do we have here? a osx-slash-dotter who doesn't read macosxhints.com? look here:

    http://www.macosxhints.com/article.php?story=20031 027224603111&query=case-sensitive

    and don't forget to watch out for the trouble:

    http://www.macosxhints.com/search.php?query=case-s ensitive&type=stories&mode=search&keyType=all

    regards, n.

  17. Bad SWF file? by bjb · · Score: 0
    Is anyone else seeing it as

    Mac%20OS%20X%20Kernel%20Presentation?

    For some reason, EVERY non-alphanumeric character is coming up in the hex format.

    --
    Never hit your grandmother with a shovel, for it leaves a bad impression on her mind...
    1. Re:Bad SWF file? by cide1 · · Score: 1

      I got that under firefox, it works fine in IE

      --
      -- the computer doesn't want any beer, no matter how much you think it does. NEVER, EVER feed your computer beer.
    2. Re:Bad SWF file? by BrianPan · · Score: 1

      Looks ok in Opera on Windows, too.

    3. Re:Bad SWF file? by aristotle-dude · · Score: 1

      Maybe you have Flashplayer 6 installed instead of Flashplayer 7?

      --
      Jesus was a compassionate social conservative who called individuals to sin no more.
  18. Flash under Windows by koehn · · Score: 1

    I take it nobody with a Windows box even tried to view the presentation. All of the space characters are rendered as "x20", which makes it a bit tough (nee impossible) to read.

    1. Re:Flash under Windows by Gulthek · · Score: 1

      Not here at work: Windows XP on a stock IBM. The presentation ran fine.

    2. Re:Flash under Windows by koehn · · Score: 1

      Weird. I'm running XP SP2 on a stock HP, and no such luck. Guess I'll try it from my Mac when I get home.

    3. Re:Flash under Windows by BiOFH · · Score: 1

      Well, that?s unfair. I mean it?s not like Mac users have had to put up with anything similar from Window?s non : standard character set choices. ;)

      --
      - I am made of meat.
    4. Re:Flash under Windows by koehn · · Score: 1

      The space character (0x20) is the same on both platforms, however. At least MacOS X switched to a more "standard" line terminator (\r\n), however inferior I might feel it is to it's MacOS = 9 equivalent (\r).

      Character encoding is truly a bane of modern software. It's kind of like Y2K, but it keeps going on forever, since nobody is going to bother switching legacy systems to support Unicode (and even then, you have multiple choices for encoding).

    5. Re:Flash under Windows by mollymoo · · Score: 1

      All good here on Win2k w. Firefox & Flash7.

      --
      Chernobyl 'not a wildlife haven' - BBC News
  19. Re:P4? by Anonymous Coward · · Score: 0

    At least they could call it a P5. Some consolation.

  20. Shocking ignorance of U.S. government activities by Futurepower(R) · · Score: 1


    It's shocking how ignorant people are of the activities of the U.S. government. Look at some of the other replies to the parent post.

    Most openly managed organizations have great difficulty staying on track. Secret organizations develop bad habits very quickly. In secret organizations, cover-ups become habit. Even the cover-ups themselves can be kept secret from other people in the same organization.

    Supposedly, U.S. spy agencies are not allowed to break U.S. laws. However, organizations that hire people to break the laws of other countries don't suddenly have moral control over the law-breakers when they return to the United States.

  21. Didn't work for me, though :-( (Safari 2, 10.4.1) by Psychic+Burrito · · Score: 1

    Bummer :-(

  22. Um, he said he didn't have tiger yet.. by Anonymous Coward · · Score: 0

    try again?