Skip to main content.

Episode 226: SSL: Santa’s Syscall List

2017-12-27

Direct Download:

This episode was brought to you by

iXsystems - Enterprise Servers and Storage for Open SourceDigitalOcean - Simple Cloud Hosting, Built for DevelopersTarsnap - Online Backups for the Truly Paranoid


Headlines

FreeBSD Q3 Status Report 2017

  • FreeBSD Team Reports
    • FreeBSD Release Engineering Team
    • Ports Collection
    • The FreeBSD Core Team
    • The FreeBSD Foundation
  • Projects
    • FreeBSD CI
  • Kernel
    • Intel 10G iflib Driver Update
    • Intel iWARP Support
    • pNFS Server Plan B
  • Architectures
    • AMD Zen (family 17h) support
  • Userland Programs
    • Updates to GDB
  • Ports
    • FreeBSDDesktop
    • OpenJFX 8
    • Puppet
  • Documentation
    • Absolute FreeBSD, 3rd Edition
    • Manual Pages
  • Third-Party Projects
    • The nosh Project

FreeBSD Foundation Q4 Update


11 syscalls that rock the world

    1. read > You cannot go wrong with a read. You can barely EFAULT it! On Linux amd64 it is syscall zero. If all its arguments are zero it returns zero. Cool!
    1. pipe > The society for the preservation of historic calling conventions is very fond of pipe, as in many operating systems and architectures it preserves the fun feature of returning both of the file descriptors as return values. At least Linux MIPS does, and NetBSD does even on x86 and amd64. Multiple return values are making a comeback in languages like Lua and Go, but C has always had a bit of a funny thing about them, but they have long been supported in many calling conventions, so let us use them in syscalls! Well, one syscall.
    1. kqueue > When the world went all C10K on our ass, and scaleable polling was a thing, Linux went epoll, the BSDs went kqueue and Solaris went /dev/poll. The nicest interface was kqueue, while epoll is some mix of edge and level triggered semantics and design errors so bugs are still being found.
    1. unshare > Sounds like a selfish syscall, but this generous syscall call is the basis of Linux namespaces, allowing a process to isolate its resources. Containers are built from unshares.
    1. setns > If you liked unshare, its younger but cooler friend takes file descriptors for namespaces. Pass it down a unix socket to another process, or stash it for later, and do that namespace switching. All the best system calls take file descriptors.
    1. execveat > Despite its somewhat confusing name (FreeBSD has the saner fexecve, but other BSDs do not have support last time I checked), this syscall finally lets you execute a program just given a file descriptor for the file. I say finally, as Linux only implemented this in 3.19, which means it is hard to rely on it (yeah, stop using those stupid old kernels folks). Before that Glibc had a terrible userspace implementation that is basically useless. Perfect for creating sandboxes, as you can sandbox a program into a filesystem with nothing at all in, or with a totally controlled tree, by opening the file to execute before chroot or changing the namespace.
    1. pdfork > Too cool for Linux, you have to head out to FreeBSD for this one. Like fork, but you get a file descriptor for the process not a pid. Then you can throw it in the kqueue or send it to another process. Once you have tried process descriptors you will never go back.
    1. signalfd > You might detect a theme here, but if you have ever written traditional 1980s style signal handlers you know how much they suck. How about turning your signals into messages that you can read on, you guessed it, file descriptors. Like, usable.
    1. wstat > This one is from Plan 9. It does the opposite of stat and writes the same structure. Simples. Avoids having chmod, chown, rename, utime and so on, by the simple expedient of making the syscall symmetric. Why not?
    1. clonefile > The only cool syscall on OSX, and only supported on the new APFS filesystem. Copies whole files or directories on a single syscall using copy on write for all the data. Look on my works, copyfilerange and despair.
    1. pledge > The little sandbox that worked. OpenBSD only here, they managed to make a simple sandbox that was practical for real programs, like the base OpenBSD system. Capsicum form FreeBSD (and promised for Linux for years but no sign) is a lovely design, and gave us pdfork, but its still kind of difficult and intrusive to implement. Linux has, well, seccomp, LSMs, and still nothing that usable for the average program.

Eleven syscalls that suck

    1. ioctl > It can‘t decide if it‘s arguments are integers, strings, or some struct that is lost in the midst of time. Make up your mind! Plan 9 was invented to get rid of this.
    1. fcntl > Just like ioctl but for some different miscellaneous operations, because one miscelleny is not enough.
    1. tuxcall > Linux put a web server in the kernel! To win a benchmark contest with Microsoft! It had it‘s own syscall! My enum tux_reactions are YUK! Don‘t worry though, it was a distro patch (thanks Red Hat!) and never made it upstream, so only the man page and reserved number survive to taunt you and remind you that the path of the righteous is beset by premature optmization!
    1. iosetup > The Linux asynchronous IO syscalls are almost entirely useless! Almost nothing works! You have to use ODIRECT for a start. And then they still barely work! They have one use, benchmarking SSDs, to show what speed you could get if only there was a usable API. Want async IO in kernel? Use Windows!
    1. stat, and its friends and relatives > Yes this one is useful, but can you find the data structure it uses? We have oldstat, oldfstat, ustat, oldlstat, statfs, fstatfs, stat, lstat, fstat, stat64, lstat64, fstat64, statfs64, fstatfs64, fstatat64 for stating files and links and filesystems in Linux. A new bunch will be along soon for Y2038. Simplify your life, use a BSD, where they cleaned up the mess as they did the cooking! Linux on 32 bit platforms is just sucky in comparison, and will get worse. And don’t even look at MIPS, where the padding is wrong.
    1. Linux on MIPS > Not a syscall, a whole implemntation of the Linux ABI. Unlike the lovely clean BSDs, Linux is different on each architecture, system calls randomly take arguments in different orders, and constants have different values, and there are special syscalls. But MIPS takes the biscuit, the whole packet of biscuits. It was made to be binary compatible with old SGI machines that don’t even exist, and has more syscall ABIs than I have had hot dinners. Clean it up! Make a new sane MIPS ABI and deprecate the old ones, nothing like adding another variant. So annoying I think I threw out all my MIPS machines, each different.
    1. inotify, fanotify and friends > Linux has no fewer than three file system change notification protocols. The first, dnotify hopped on ioctl‘s sidekick fcntl, while the two later ones, inotify and fanotify added a bunch more syscalls. You can use any of them, and they still will not provide the notification API you want for most applications. Most people use the second one, inotify and curse it. Did you know kqueue can do this on the BSDs?
    1. personality > Oozing in personality, but we just don’t get along. Basically obsolete, as the kernel can decide what kind of system emulation to do from binaries directly, it stays around with some use cases in persuading ./configure it is running on a 32 bit system. But it can turn off ASLR, and let the CVEs right into your system. We need less persoanlity!
    1. gettimeofday > Still has an obsolete timezone value from an old times when people thought timezones should go all the way to the kernel. Now we know that your computer should not know. Set its clock to UTC. Do the timezones in the UI based on where the user is, not the computer. You should use clock_gettime now. Don’t even talk to me about locales. This syscall is fast though, don’t use it for benchmarking, its in the VDSO.
    1. splice and tee > These, back in 2005 were a quite nice idea, although Linux said then “it is incomplete, the interfaces are ugly, and it will oops the system if anything goes wrong”. It won’t oops your system now, but usage has not taken off. The nice idea from Linus was that a pipe is just a ring buffer in the kernel, that can have a more general API and use cases for performant code, but a decade on it hasn’t really worked out. It was also supposed to be a more general sendfile, which in many ways was the successor of that Tux web server, but I think sendfile is still more widely used.
    1. userfaultfd > Yes, I like file descriptors. Yes CRIU is kind of cool. But userspace handling page faults? Is nothing sacred? I get that you can do this badly with a SIGSEGV handler, but talk about lipstick on a pig.

OpenBSD 6.0 on an iMac G3 from 1999

A while ago I spent $50 for an iMac G3 (aka the iMac,1). This iconic model restored Apple's fortunes in the late '90s. Since the iMac G3 can still boot Mac OSes 8 and 9, I mostly use the machine to indulge a nostalgia for childhood schooldays spent poking at the operating system and playing Escape Velocity. But before I got around to that, I decided to try out the software that the previous owner had left on the machine. The antiquated OSX 10.2 install and 12 year old versions of Safari and Internet Explorer were too slow and old to use for anything. Updating to newer software was almost impossible; a later OSX is required to run the little PowerPC-compatible software still languishing in forgotten corners of the Internet. This got me thinking: could this machine be used, really used, nowadays? Lacking a newer OSX disc, I decided to try the most recent OpenBSD release. (And, since then, to re-try with each new OpenBSD release.) Below are the results of this experiment (plus a working xorg.conf file) and a few background notes. + Background This iMac is a Revision D iMac G3 in grape. It's part of the iMac,1 family of computers. This family includes all tray-loading iMac G3s. (Later iMac G3s had a slot-loading CD drive and different components.) Save for a slightly faster processor, a dedicated graphics card, and cosmetic tweaks to the case, my iMac is identical to the prior year's line-launching Bondi Blue iMac. My machine has had its memory upgraded from 32 MB to 320 MB. Thank Goodness. The Revision D iMac G3 shipped with Mac OS 8.5. It can run up to Mac OS 9.2.2 or OSX 10.3.9. Other operating systems that tout support for the iMac,1 include NetBSD, OpenBSD, and a shrinking number of Linux distributions. OpenBSD is simple (by design) and well-maintained. In contrast, NetBSD seems rather more complex and featureful, and I have heard grumbling that despite its reputation for portability, NetBSD really only works well on amd64. I'd test that assertion if OpenBSD's macppc installation instructions didn't seem much simpler than NetBSD's. Linux is even more complicated, although most distros are put together in a way that you can mostly ignore that complexity (until you can't). In the end I went with OpenBSD because I am familiar with it and because I like it. + Installing OpenBSD on the iMac,1 Installing OpenBSD on this iMac was simple. It's the same procedure as installing OpenBSD on an amd64 rig. You put in the installation disc; you tell the machine to boot from it; and then you answer a few prompts, most of which simply ask you to press enter. In this case, OpenBSD recognizes all machine's hardware just fine, including sound and networking, though I had a little trouble with video. The OpenBSD documentation says video should just work and that an xorg.conf file isn't necessary. As such, it no longer ships with an xorg.conf file. Though that's never posed a problem on my other OpenBSD machines, it does here. Video doesn't work out of the box on my iMac,1. startx just blanks the screen. Fortunately, because the BSDs use a centralized development model where each operating system is stored in one repository, OpenBSD's website provides a web interface to the source code going back to the early days. I was able to find the last version of the sample xorg.conf that used to ship on macppc. With a little tweaking, I transformed that file into this one, with which video works just fine. Just drop it into your iMac's /etc/X11 directory. You'll also need to remember to set the machdep.allowaperture sysctl to 2 (e.g., as root run sysctl machdep.allowaperture=2), although the installer will do that automatically if you answer yes to the question about whether you plan to run X. All that being said, video performance is pretty poor. I am either doing something wrong, or OpenBSD doesn't have accelerated video for this iMac, or this machine is just really old! I will discuss performance below. + Running OpenBSD on the iMac,1 The machine performs okay under OpenBSD. You can expect to ably run minimalistic software under minimalistic window managers. I tried dillo, mrxvt, and cmus under cwm and fvwm. Performance here was just fine. I also tried Firefox 26, 33, and 34 under fvwm and cwm. Firefox ran, but "modern," Javascript-heavy sites were an exercise in frustration; the 2015 version of CNN.com basically froze Firefox for 30 seconds or more. A lighter browser like dillo is doable. You'll notice that I used the past-tense to talk about Firefox. Firefox currently doesn't build on PowerPC on OpenBSD. Neither does Chromium. Neither do a fair number of applications. But whatever -- there's still a lot of lighter applications available, and it's these you'll use day-to-day on a decades-old machine. Lightweight window managers work okay, as you'd expect. You can even run heavier desktop environments, such as xfce, though you'll give up a lot of performance. I ran the Ubench benchmark on this iMac and two more modern machines also running OpenBSD. The benchmark seems like an old one; I don't know how (if at all) it accounts for hardware changes in the past 13 years. That is, I don't know if the difference in score accurately measures the difference in real-world performance. Here are the results anyway: + Conclusion Except for when I check to see if OpenBSD still works, I run Mac OS9 on this rig. I have faster and better machines for running OpenBSD. If I didn't -- if this rig were, improbably, all I had left, and I was waiting on the rush delivery of something modern -- then I would use OpenBSD on my iMac,1. I'd have to stick to lightweight applications, but at least they'd be up-to-date and running on a simple, stable, OS.


News Roundup

34th Chaos Communication Congress Schedule


OpenBSD 6.2 + CDE

If you've noticed a disruption in the time-space continuum recently, it is likely because I have finally been able to compile and install the Common Desktop Environment (CDE) in a current and actively-developed operating system (OpenBSD 6.2 in this case). This comes after so many attempts (across multiple platforms) that ended up with the build process prematurely stopping itself in its own tracks for a variety of infinitesimal reasons that were beyond my comprehension as a non-programmer, or when there was success it was not without some broken parts. As for the latter, I've been able to build CDE on OpenIndiana Hipster, but with an end product where I'm unable to change the color scheme in dtstyle (because "useColorObj" is set to "False"), with a default color scheme that is low-res and unpleasant. As for changing "useColorObj" to "True", I tried every recommended trick I could find online, but nothing worked. My recent attempts at installing CDE on OpenBSD (version 6.1) saw the process stop due to a number of errors that are pure gibberish to these naive eyes. While disappointing, it was par for the course within my miserable experience with trying to build this particular desktop environment. As I wrote in this space in November 2015, in the course of explaining part of my imperitive for installing Solaris 10: And so I have come to think of building the recently open-sourced CDE as being akin to a coffee mug I saw many years ago. One side of the mug read "Turn the mug to see how to keep an idiot busy." On the other side, it read "Turn the mug to see how to keep an idiot busy." I'm through feeling like an idiot, which is partially why I'm on this one-week journey with Solaris 10. While I thoroughly enjoyed running Solaris 10 on my ThinkPad T61p, and felt a devilish thrill at using it out in the open at my local MacBook- and iPhone-infested Starbucks and causing general befuddlement and consternation among the occasional prying yoga mom, I never felt like I could do much with it beyond explore the SunOS 5.10 command line and watch YouTube videos. While still supported by its current corporate owner (whose name I don't even want to type), it is no longer actively developed and is thus little more than a retro toy. I hated the idea of installing anything else over it, but productivity beckoned and it was time to tearfully and reluctantly drag myself off the dance floor. In any case, just last week I noticed that the Sourceforge page for the OpenBSD build had some 6.2-specific notes by way of a series of four patches, and so I decided 'what the heck, let's give this puppy another whirl'. After an initial abortive attempt at a build, I surmised that I hadn't applied the four patches correctly. A day or two later, I took a deep breath and tried again, this time resolving to not proceed with the time make World build command until I could see some sign of a successful patch process. (This time around, I downloaded the patches and moved them into the directory containing the CDE makefiles, and issued each patch command as patch <filename.patch and then reading the output carefully to determine which file in the source code was to be patched, and entering the filename when asked.) Once I had the thing up and running, and with a mind bursting with fruit flavor, I started messing about. The first order of business was to create a custom color scheme modelled after the default color scheme in UnixWare. (Despite any baggage that system carries from its previous ownership under SCO, I adored the aesthetics of UnixWare 7.1.4 two years ago when I installed the free one month trial version on my ThinkPad. For reasons that escape me now, I named my newly-created color scheme in honor of UnixWare 7.1.3.) Like a proud papa, I immediately tweeted the above screenshot and risked irritating a Linux kid or two in the process, given SCO's anti-climatic anti-Linux patent trolling from way back when. (I'm not out to irritate penguinistas, I just sure like this color scheme.) + Final Thoughts It may look a little clunky at first, and may be a little bling-challenged, but the more I use CDE and adapt to it, the more it feels like an extension of my brain. Perhaps this is because it has a lot zip and behaves in a consistent and coherent manner. (I don't want to go too much further down that road here, as OSnews's Thom Holwerda already gave a good rundown about ten years ago.) Now that I have succesfully paired my absolute favorite operating system with a desktop environment that has exerted an intense gravitational hold on me for many, many years, I don't anticipate distrohopping any time soon. And as I attain a more advanced knowledge of CDE, I'll be chronicling any new discoveries here for the sake of anyone following me from behind as I feel my way around this darkened room.


devmatch(8) added to FreeBSD HEAD

``` Log: Match unattached devices on the system to potential kernel modules.

devmatch(8) matchs up devices in the system device tree with drivers that may match them. For each unattached device in the system, it tries to find matching PNP info in the linker hints and prints modules to load to claim the devices.

In --unbound mode, devmatch can look for drivers that have attached to devices in the device tree and have plug and play information, but for which no PNP info exists. This helps find drivers that haven't been converted yet that are in use on this system.

In addition, the ability to dump out linker.hints is provided.

Future commits will add hooks to devd.conf and rc.d to fully automate using this information. Added: head/usr.sbin/devmatch/ head/usr.sbin/devmatch/Makefile (contents, props changed) head/usr.sbin/devmatch/devmatch.8 (contents, props changed) head/usr.sbin/devmatch/devmatch.c (contents, props changed) Modified: head/usr.sbin/Makefile Modified: head/usr.sbin/Makefile ``` + Oh, you naughty committers: :-) https://www.mail-archive.com/svn-src-all@freebsd.org/msg154720.html


Beastie Bits


Feedback/Questions


  • Send questions, comments, show ideas/topics, or stories you want mentioned on the show to feedback@bsdnow.tv

Latest News

New announcement

2017-05-25

Hi, Mr. Dexter. Also, we understand that Brad Davis thinks there should be more real news....

Two Year Anniversary

2015-08-08

We're quickly approaching our two-year anniversary, which will be on episode 105. To celebrate, we've created a unique t-shirt design, available for purchase until the end of August. Shirts will be shipped out around September 1st. Most of the proceeds will support the show, and specifically allow us to buy...

New discussion segment

2015-01-17

We're thinking about adding a new segment to the show where we discuss a topic that the listeners suggest. It's meant to be informative like a tutorial, but more of a "free discussion" format. If you have any subjects you want us to explore, or even just a good name...

How did you get into BSD?

2014-11-26

We've got a fun idea for the holidays this year: just like we ask during the interviews, we want to hear how all the viewers and listeners first got into BSD. Email us your story, either written or a video version, and we'll read and play some of them for...


Episode 232: FOSDEM 2018

2018-02-07

Direct Download:HD VideoMP3 AudioTorrent> This episode was brought to you by Headlines [FOSDEM Trip report] Your BSDNow hosts were both at FOSDEM in Brussels, Belgium over the weekend. On the friday before FOSDEM, we held a FreeBSD devsummit (3rd consecutive year), sponsored by the FreeBSD Foundation and organized by Benedict (with the help from Kristof...

Episode 231: Unix Architecture Evolution

2018-01-24

Direct Download:HD VideoMP3 AudioTorrent This episode was brought to you by Headlines Unix Architecture Evolution from the 1970 PDP-7 to the 2017 FreeBSD Q: Could you briefly introduce yourself? I’m a professor of software engineering, a programmer at heart, and a technology author. Currently I’m also the editor in chief of the IEEE...

Episode 230: Your questions, Part III

2018-01-24

Direct Download:HD VideoMP3 AudioTorrent> This episode was brought to you by Headlines KPTI patch lands in FreeBSD -current After a heroic effort by Konstantin Belousov kib@FreeBSD.org, the first meltdown patch has landed in FreeBSD This creates separate page tables for the Kernel and userland, and switches between them when executions enters the kernel, and when...

Episode 229: The Meltdown of Spectre

2018-01-17

Direct Download:HD VideoMP3 AudioTorrent> This episode was brought to you by Headlines More Meltdown Much has been happened this week, but before we get into a status update of the various mitigations on the other BSDs, some important updates: Intel has recalled the microcode update they issued on January 8th. It turns out this update...