Category Archives: Linux

An investigation of the forces behind the age-verification bills

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Reddit user “Ok_Lingonberry3296” has posted the
results of an extensive investigation into the companies that are
pushing US state legislatures to enact age-verification bills.

I’ve been pulling public records on the wave of “age verification”
bills moving through US state legislatures. IRS 990 filings, Senate
lobbying disclosures, state ethics databases, campaign finance
records, corporate registries, WHOIS lookups, Wayback Machine
archives. What started as curiosity about who was pushing these
bills turned into documenting a coordinated influence operation
that, from a privacy standpoint, is building surveillance
infrastructure at the operating system level while the company
behind it faces zero new requirements for its own platforms.

(See also this article for a look at the
California law.)

A set of AppArmor vulnerabilities

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Qualys has sent out a
somewhat breathless advisory describing a number of vulnerabilities in
the AppArmor security module, which is used in a number of Debian-based
distributions (among others).

This “CrackArmor” advisory exposes a confused-deputy flaw allowing
unprivileged users to manipulate security profiles via
pseudo-files, bypass user-namespace restrictions, and execute
arbitrary code within the kernel. These flaws facilitate local
privilege escalation to root through complex interactions with
tools like Sudo and Postfix, alongside denial-of-service attacks
via stack exhaustion and Kernel Address Space Layout Randomization
(KASLR) bypasses via out-of-bounds reads.

Linux 6.12 Through Linux 7.0 File-System Benchmarks For EXT4 + XFS

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Earlier this month were various Linux 7.0 file-system benchmarks showing how XFS is leading the race in the overall upstream Linux file-system performance on this forthcoming kernel. Stemming from that testing some premium supporters requested a fresh look at the historical performance of XFS as well as EXT4. So today’s article is a look at how XFS and EXT4 have performed on every kernel release going back to Linux 6.12 LTS.

[$] More timing side-channels for the page cache

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In 2019, researchers published a way to
identify which file-backed pages
were being accessed on a system using timing information from the page cache,
leading to a handful of unpleasant consequences and a change to the design of
the

mincore() system call. Discussion at the time
led to a number of ad-hoc patches to address the
problem. The lack of new page-cache attacks suggested that attempts to fix
things in a piecemeal fashion had succeeded. Now, however, Sudheendra Raghav Neela,
Jonas Juffinger, Lukas Maar, and Daniel Gruss have
found a new set of
holes in the Linux kernel’s page-cache-timing protections that allow
the same general class of attack.