Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-30 Thread Jonathan Amery
[Apologies to readers of debian-sparc, who have already received a copy of this] In article [EMAIL PROTECTED] [EMAIL PROTECTED] write: [XDM randomness] /dev/random? /dev/urandom? You are kidding. This randmomness is used to create authorisation cookies for X which in my understanding provide

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-30 Thread Jonathan Amery
In article [EMAIL PROTECTED] Kusti writes: I believe the /dev/mem gets read only in systems where no /dev/(u)random exists. Actually, the standard configuration is that /dev/mem is read. The code to read from /dev/(u)random isn't activated in any situation in the standard upstream X

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-30 Thread Jonathan Amery
In article [EMAIL PROTECTED] Branden writes: I can't believe he actually intends to keep it like this.. I'm going to #define DEV_RANDOM /dev/random for Linux systems. And Debian Hurd? Or does the Hurd not have /dev/random or /dev/urandom? I suspect that /dev/urandom may be the better choice,

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-30 Thread Marcus Brinkmann
On Fri, Aug 30, 2002 at 01:58:43PM +0100, Jonathan Amery wrote: In article [EMAIL PROTECTED] Branden writes: I can't believe he actually intends to keep it like this.. I'm going to #define DEV_RANDOM /dev/random for Linux systems. And Debian Hurd? Or does the Hurd not have /dev/random or

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-27 Thread Helge Kreutzmann
Hello ! This programm works on 20164 (LX) running Debian/GNU Linux (Woody) 20164 (dual) running Digital Unix (using Compaq C-Compiler) 20264 (XP1000) running Linux Greetings Helge -- Helge Kreutzmann, Dipl.-Phys. [EMAIL PROTECTED] gpg signed mail preferred

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-27 Thread Derek L Davies
Marcus Brinkmann [EMAIL PROTECTED] writes: You are mistaken. Do yourself a favour and get a book about (pseudo) random number generators, entropy, hash functions and cryptography. If you don't start with random numbers, you can turn the numbers upside down, it won't get any more random than

re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread matthew green
Be warned: on at least some architectures (notably IA-64), this sort of read has been known to cause untrapped machine checks (a.k.a., lockups or spontaneous reboots). Arguably the kernel should trap this sort of nonsense, so you may be in the mood to file a bug against kernel

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Branden Robinson
On Mon, Aug 26, 2002 at 04:28:38PM +1000, matthew green wrote: wow, this is such a bad idea. It originated upstream. In fact, judging by CVS logs it has been in xdm's source for many, many years. why don't you use /dev/urandom if it exists, as it does on pretty much all modern UNIX

re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread matthew green
On Mon, Aug 26, 2002 at 04:28:38PM +1000, matthew green wrote: wow, this is such a bad idea. It originated upstream. mmm, xdm. In fact, judging by CVS logs it has been in xdm's source for many, many years. bad ideas often hang around for a long time. the only

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Helge Kreutzmann
Hello ! I'll run it later on different alphas, but I checked it on a ppc-machine running AIX if this is of any interest to you: [EMAIL PROTECTED]: /root # ./readmem.aix.x Reading data from /dev/mem... read #2 of 8192 bytes ... read #1024 of 8192 bytes done with read of /dev/mem (returned 1).

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Filip Van Raemdonck
Hi, On Mon, Aug 26, 2002 at 05:04:26PM +1000, matthew green wrote: why don't you use /dev/urandom if it exists, as it does on pretty much all modern UNIX platforms? I see you haven't read the thread. actually, i hadn't, but there wasn't very much there besides the fact that

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Kimmo K. I. Surakka
On Mon, 26 Aug 2002 17:04:26 +1000 matthew green [EMAIL PROTECTED] wrote: actually, i hadn't, but there wasn't very much there besides the fact that people found it was xdm reading /dev/mem and a small patch for debian to enable /dev/random (i'd suggest /dev/urandom). my point is that on

RE: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Julian Mehnle
Filip Van Raemdonck [EMAIL PROTECTED] wrote: On Mon, Aug 26, 2002 at 05:04:26PM +1000, matthew green wrote: actually, i hadn't, but there wasn't very much there besides the fact that people found it was xdm reading /dev/mem and a small patch for debian to enable /dev/random (i'd suggest

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Thomas Horsten
On Mon, Aug 26, 2002 at 05:04:26PM +1000, matthew green wrote: actually, i hadn't, but there wasn't very much there besides the fact that people found it was xdm reading /dev/mem and a small patch for debian to enable /dev/random (i'd suggest /dev/urandom). If any of these it should be

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Wichert Akkerman
Previously Kimmo K. I. Surakka wrote: I think the safe way of getting random data without a decent random source would be to write one. This, however, would be more that just a small patch. There is existing code to generate randomness from userland, look at what current OpenSSH does for

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Niels Möller
matthew green [EMAIL PROTECTED] writes: my point is that on modern systems we simply should not read from /dev/mem for these purposes _ever_. It would make some sense to read all the physical memory in the machine. Unfortunately, I'm not aware of any reasonably way to do that. Reading /dev/mem

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Carlos O'Donell
Branden, The long story, for those interested: http://lists.debian.org/debian-x/2002/debian-x-200208/msg00091.html (and read the whole thread) The short story: I need people with root on machines of your given architecture to compile and run the attached C program. It consists of code

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Joey Hess
matthew green wrote: bad ideas often hang around for a long time. the only surprising thing to me is how long this one has taken to surface... Perhaps Branden is gathering information about what a bad idea this really is, to show upstream the error of their ways. I can't believe he actually

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Matthew Wilcox
On Mon, Aug 26, 2002 at 09:06:00AM -0400, Carlos O'Donell wrote: Done. I've submitted the output for HPPA boxes running 32 and 64-bit kernels. Looks like they pass without any problem. I'll pass on the yes, but it may well crash them. some parts of /dev/mem map random IO addresses which may

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Branden Robinson
On Mon, Aug 26, 2002 at 10:23:06AM -0400, Joey Hess wrote: matthew green wrote: bad ideas often hang around for a long time. the only surprising thing to me is how long this one has taken to surface... Perhaps Branden is gathering information about what a bad idea this really is, to show

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Marcus Brinkmann
On Mon, Aug 26, 2002 at 12:50:22PM -0500, Branden Robinson wrote: I can't believe he actually intends to keep it like this.. I'm going to #define DEV_RANDOM /dev/random for Linux systems. That's bad, because that will drain the entropy a lot, and it might block for a long time, and that for

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Matthew Wilcox
On Mon, Aug 26, 2002 at 09:10:54PM +0200, Marcus Brinkmann wrote: Also, reading /dev/mem doesn't sound very secure at all (even if it works) because the patterns in the memory of a computer are probably predictable and a lot of information can be observed from the outside (which processes are

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Marcus Brinkmann
On Mon, Aug 26, 2002 at 08:16:06PM +0100, Matthew Wilcox wrote: On Mon, Aug 26, 2002 at 09:10:54PM +0200, Marcus Brinkmann wrote: Also, reading /dev/mem doesn't sound very secure at all (even if it works) because the patterns in the memory of a computer are probably predictable and a lot of

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Jeff Sheinberg
Marcus Brinkmann writes: On Mon, Aug 26, 2002 at 12:50:22PM -0500, Branden Robinson wrote: I can't believe he actually intends to keep it like this.. I'm going to #define DEV_RANDOM /dev/random for Linux systems. That's bad, because that will drain the entropy a lot, and it might

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Branden Robinson
On Mon, Aug 26, 2002 at 09:10:54PM +0200, Marcus Brinkmann wrote: On Mon, Aug 26, 2002 at 12:50:22PM -0500, Branden Robinson wrote: I can't believe he actually intends to keep it like this.. I'm going to #define DEV_RANDOM /dev/random for Linux systems. That's bad, because that will

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Branden Robinson
On Mon, Aug 26, 2002 at 03:28:18PM -0400, Jeff Sheinberg wrote: Why does anyone need to read megabytes of urandom? Nobody does. Or, at least, xdm doesn't. Markus is opining without the benefit of having checked the facts. -- G. Branden Robinson| What influenced me to

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Marcus Brinkmann
On Mon, Aug 26, 2002 at 02:44:26PM -0500, Branden Robinson wrote: On Mon, Aug 26, 2002 at 03:28:18PM -0400, Jeff Sheinberg wrote: Why does anyone need to read megabytes of urandom? Nobody does. Or, at least, xdm doesn't. Markus is opining without the benefit of having checked the facts.

Re: a small C program to test xdm's /dev/mem reading on your architecture

2002-08-26 Thread Richard Zidlicky
On Mon, Aug 26, 2002 at 09:10:54PM +0200, Marcus Brinkmann wrote: On Mon, Aug 26, 2002 at 12:50:22PM -0500, Branden Robinson wrote: I can't believe he actually intends to keep it like this.. I'm going to #define DEV_RANDOM /dev/random for Linux systems. That's bad, because that will