Xz: Can you spot the single character that disabled Linux landlock?

Post by masklinn » Sun, Mar 31, 2024, 6:30 AM UTC

astrange wrote: post #142

Aurornis wrote: post #5

Earlier quoted context omitted.

The function is “check_c_source_compiles”. The comment indicates that the intention is to confirm that the Landlock functionality can be compiled on the system, in which case it will be enabled. The stray dot isn’t valid C, so it will never compile. By ensuring it can never compile, Landlock will never be enabled.

configure would print that it's not enabled, so it seems like the kind of thing people would eventually notice.

Post by takeda » Sun, Mar 31, 2024, 6:44 AM UTC

eru wrote: post #91

tomoyoirl wrote: post #44

Earlier quoted context omitted.

“The thing that controls scope is the count of certain nonprinting characters, which happen to come in multiple widths” is reasonably insane, yes

Which non-printing characters are you talking about? Whitespace characters are very much printable. Yes, I agree that Python should just forbid tabs. As a second best, you can tell your linter (and/or formatter) to forbid tabs (and any weird unicode whitespace). That's basically the equivalent of compiling your C with -Wall.

Post by Dalewyn » Sun, Mar 31, 2024, 6:47 AM UTC

kristopolous wrote: post #132

Dalewyn wrote: post #127

Earlier quoted context omitted.

>How can we ensure say, that Microsoft doesn't pay someone to throw a wrench in libre office development or Adobe to sabotage Gimp? Microsoft and Adobe have reputations to uphold long into the future. Is that infallible? Hell no it isn't, but consider that Jia Tan only needed to uphold his reputation insofar as getting his backdoor onto everyone's systems. Once that is done, his reputation or the lack thereof becomes…

Those companies are famous for skullduggery. They can secure the dominance of their offering against the open source competition for well under 500k a year. It's a no brainer. What this might look like would be say, poorly discernable icons, clumsy UI design, or an unstable API that makes plugins constantly break. Large volumes of documentation that are inadequate or inaccurate in critical places, etc. If I was malic…

Post by maxdamantus » Sun, Mar 31, 2024, 6:56 AM UTC

eacapeisfutuile wrote: post #104

fcanesin wrote: post #99

Geez, his last commit is making security reports worse: https://git.tukaani.org/?p=xz.git;a=commitdiff;h=af071ef7702...

Why is that accepted? Serious question

Post by jwilk » Sun, Mar 31, 2024, 6:59 AM UTC

akdev1l wrote: post #158

usr1106 wrote: post #148

Where/how was landlock supposed to be used? I guess you cannot really use it in a generic library like compression/decompression. The library has no clue what the program is supposed to do and what should be restricted. For a program it might be clearer. The sshd attack was using liblzma as a library. So disabling landlock seems unrelated? A sign that there is more bad code waiting to be detected / had been planned t…

Presumably sshd itself used to lock down its own capabilities after a certain point of execution. Removing the landlock means the daemon doesn’t lock itself down and will allow for better payload execution when they get to the exploitation stage. I don’t think these two things are unrelated. I think they already had payloads in mind and realized this would be a hurdle.