"Az OpenBSD fejlesztők nekiálltak kigyepálni a veszélyesnek minősített sztring kezelő függvények kódját, és elkezdték helyettük beépíteni a saját határ-ellenőrzéssel (boundary check) ellátott függvényeket." - írtam kb. két héttel ezelőtt.
Theo de Raadt egy levelet postázott az openbsd-misc listára, amelyben összefoglalja a a munka eredményeit. A tisztogatási munka eredményeképpen kb. 2000 ilyen függvényt távolítottak el a kódbázisból. A munka azonban még nincs befejezve.
Theo levele:List: openbsd-misc
Subject: string cleanup results
From: Theo de Raadt
Date: 2003-04-19 19:54:53
Some of you might have noticed that we have been doing a 'string cleaning'. (I should probably apologize for this northern-hemisphere specific pun).
That means that we have been going through the tree cleaning out all calls to sprintf(), strcpy(), and strcat(). Instead, these things are being rewritten to use asprintf(), snprintf(), strlcpy(), and strlcat().
As a result, I can tell you that we have removed at approximately 2000 occurances of these functions. I cannot provide exact figures since that would require hand-counting the actual diffs from 8 weeks ago ;) Source code grep'ing is not always accurate.
The goal is to remove potential overflows, by always calculating what the bounds of an operation are. In doing so, some code is now converted from an overflow to a truncation. In followup work, we wish to continue investigating all cases of truncation in the tree, and see what we can do better in those cases where truncation is undesirable. Sometimes you want to handle it, sometimes it is ok, sometimes it is really nasty. Obviously, that's an even bigger job than what we have done here, since the tree was already full of truncations. Current
theory held by most is that most of these are innocious, but who knows.. I want us to clean them (but I do not want us to go insane either).
Obviously there is the possibility that this huge effort has
introduced a minor bug here or there, but it much more likely that we have squished many much more major bugs.
I would estimate that more than 20 developers have been involved in this process which we started in earnest about 6 weeks ago.
We are obviously not doing this to some parts of the tree which we borrow from other projects. In particular, the gnu part of the tree might remain largely dirty. However, we have done this in httpd and openssl, and will maintain those tree components ourself if need be. We have also convinced the bind people to move in this direction, and they have incorporated these functions into bind -- that work is not finished however. Since sendmail already has renamed versions of strlcpy and strlcat, we have tried convincing them to move completely in this direction as well, and I think that they are doing that work now.
Of the programs that are in our base set, and under consideration, we have a few that still call these functions:
routed, dump, restore, awk, indent, lam,
make, xlint, bind, openssl, ppp, rtadvd
Pretty small list eh.
There might be a few more, but I am sure you can comprehend the direction. Of course, we have completely purified our libraries of these functions as well, except that libc still provides them (in accordance with standards and... well, expected behaviour).
The remaining ones are very difficult. afs, gcc, binutils, etc.
I must also say that in the last week we've fixed some that are incredibly difficult. Some of them were definate buffer overflows. Sometimes we hit a piece of code in a program that just about made us cry. A few changes involved 10 or more people before we settled on a correct change. Crazy stuff.
In a week or so there will also be changes made to ensure that the kernel is completely clear of these functions too, but we are waiting for the i386 ELF W^X work to settle into the tree.
A Sharp új Zaurus SL-5600-as gépe egy Linux alapú PDA, amelyet egy 400MHz-es Intel XScale (PXA250) CPU hajt. Az utcai ára a stuffnak jelenleg 500 amerikai dollár körül van. A Sharp ezt a gépet Personal Mobile Tool-nak nevezi, de az áttekintő cikk írója inkább egy "Ultra-könnyű számítógépnek" nevezné.
Dru a DHCP (Dynamic Host Configuration Protocol) hasznosságáról próbál meggyőzni minket legújabb cikkében. Ismerteti a DHCP szerver és DHCP kliens gépek beállításának folyamatát, a DHCP adta lehetőségeket. A cikk több részből fog állni, ez a bevezető. És ha Dru Lavigne akkor a cikk természetesen FreeBSD operációs rendszerről szól ;-)Dru Lavigne hálózati ismereteket oktató tanárnő, instruktor egy magániskolában Kingstonban (ON). Az a hír járja róla, hogy a célja az, hogy minél több operációs rendszert tudjon bootolni egyszerre a tesztgépén. 1997-ben egy bug után nyomoztott az Interneten, a Yahoo keresője a FreeBSD oldalára vetette, azóta megszállott FreeBSD felhasználó. Szabadidejében TCP/IP adminisztációs könyveket és RFC-ket olvas.
