Landlock shines when an application has a predictable set of files
or directories it needs. For example, a web server could restrict
itself to accessing only /var/www/html and /tmp.
Unlike SELinux or AppArmor, Landlock policies don’t require
administrator involvement or system-wide configuration. Developers
can embed policies directly in application code, making sandboxing
a natural part of the development process.
Linus has released 6.18-rc7, probably the
last -rc before the 6.18 release.
So the rc6 kernel wasn’t great: we had a last-minute core VM
regression that caused people problems.
That’s not a great thing late in the release cycle like that, but
it was a fairly trivial fix, and the cause wasn’t some horrid bug,
just a latent gotcha that happened to then bite a late VM fix. So
while not great, it also doesn’t make me worry about the state of
6.18. We’re still on track for a final release next weekend unless
some big new problem rears its ugly head.
The Oracle blog has a
lengthy article on enhancements to GCC to help detect overflows of
flexible array members (FAMs) in C programs.
We describe here two new GNU extensions which specify size
information for FAMs. These are a new attribute,
“counted_by” and a new builtin function,
“__builtin_counted_by_ref“. Both extensions can be used in
GNU C applications to specify size information for FAMs, improving
the buffer overflow detection for FAMs in general.
The call for
candidates for the 2025 election for the Linux Foundation Technical
Advisory Board has been posted.
The TAB exists to provide advice from the kernel community to the
Linux Foundation and holds a seat on the LF’s board of directors;
it also serves to facilitate interactions both within the community
and with outside entities. Over the last year, the TAB has
overseen the organization of the Linux Plumbers Conference, advised
on the setup of the kernel CVE numbering authority, worked behind
the scenes to help resolve a number of contentious community
discussions, worked with the Linux Foundation on community
conference planning, and more.
Other changes include a new function attribute, “#[\NoDiscard]” to
indicate that the return value should be used, attributes on constants, and
more; see the
migration guide for details.
BPF allows programs uploaded from user space to be run, safely, within the
kernel. The io_uring subsystem, too, can be thought of as a way of loading
programs in the kernel, though the programs in question are mostly a
sequence of I/O-related system calls. It has sometimes seemed inevitable
that io_uring would, like many other parts of the kernel, gain BPF
capabilities as a way of providing more flexibility to user space. That
has not yet happened, but there are currently two patches sets under
consideration that take different approaches to the problem.
Version 2.52.0 of the Git
source-code management system has been released. Changes include a new last-modified command to find the closest ancestor commit that
touched one or more paths, a couple of git refs improvements, a
new git repo command for obtaining information about the
repository itself, and more. See the announcement and this
GitHub blog entry for more information.
For better or for worse, the NUMA node is the abstraction used by the
kernel to keep track of different types of memory. How that abstraction is
used, though, is still an active area of development. Two patch sets
focused on this problem are currently under review; one addresses the
perennial problem of promoting heavily used folios from slower to faster
memory, while the other aims to improve the kernel’s handling of nodes
containing special memory installed for a specific purpose.
Linus has released 6.18-rc6 for testing.
“So we have a slightly larger rc6 than usual, but I think it’s just the
random noise and a result of pull request timings rather than due to any
issues with the release. But I guess we have a couple of weeks remaining to
find out.“
One of the many objectives of the Linux
Kernel Self-Protection Project (KSPP), which just completed ten years of
work, is to ensure that all array references can be bounds-checked,
even in the case of flexible array members, the size of which is not known
at compile time. One of the most challenging flexible array members in the
kernel is not even declared as such. Almost exactly one year ago, LWN looked at the effort to increase safety around
the networking subsystem’s heavily used sockaddr structure. One
year later, Kees Cook is still looking for a way to bring this work to a
close.
The Google Security Blog has a
new post on just how well the use of Rust is working out for the
Android project.
We adopted Rust for its security and are seeing a 1000x reduction
in memory safety vulnerability density compared to Android’s C and
C++ code. But the biggest surprise was Rust’s impact on software
delivery. With Rust changes having a 4x lower rollback rate and
spending 25% less time in code review, the safer path is now also
the faster one.
Version 2.0.0 of public-inbox, the mail archiving system behind
lore.kernel.org and LWN’s email archive, has been released. “This
release includes several new features and fixes; mostly around improved
integration between inboxes and coderepos for solver. Portability and
reliability is also improved, especially in the internal process management
of lei.”
The kernel community is currently reviewing a
proposed policy for contributors who are using large language models to
assist in the creation of their patches; the primary focus is on disclosure
of the use of those tools. “The goal here is to clarify community
expectations around tools. This lets everyone become more productive while
also maintaining high degrees of trust between submitters and
reviewers.“
The future of the Filesystem Hierarchy Standard (FHS) has been under discussion for some time; now,
Neal Gompa has announced
that the FHS is “hosted and stewarded” by Freedesktop.org.
For those who are unaware, the Filesystem Hierarchy Standard (FHS)
is the definition for POSIX operating systems to organize system
and user data. It is broadly adopted by Linux, BSD, and other
operating systems that follow POSIX-like conventions.
Filesystems are complex and performance-sensitive beasts. They can also
present security concerns. Microkernel-based systems have long pushed
filesystems into separate processes in order to contain any vulnerabilities
that may be found there. Linux can do the same with the Filesystem in
Userspace (FUSE) subsystem, but using FUSE brings a significant
performance penalty. Darrick Wong is working on ways to eliminate that
penalty, and he has a massive patch
set showing how ext4 filesystems can be safely implemented in user space by
unprivileged processes with good performance. This work has the potential
to radically change how filesystems are managed on Linux systems.
The Project Zero blog explains
that, on 64-bit Arm systems, the kernel’s direct map is always placed at
the same virtual location, regardless of whether kernel address-space
layout randomization (KASLR) is enabled.
While it remains true that KASLR should not be trusted to prevent
exploitation, particularly in local contexts, it is regrettable
that the attitude around Linux KASLR is so fatalistic that putting
in the engineering effort to preserve its remaining integrity is
not considered to be worthwhile. The joint effect of these two
issues dramatically simplified what might otherwise have been a
more complicated and likely less reliable exploit.
Version
6.0 (“Excalibur”) of the systemd-averse Devuan distribution has been
released. It is based on Debian 13 (“trixie”), and includes some of
the significant changes from that release, including the merged /usr hierarchy. See the
release notes for details.
The collective thoughts of the interwebz
Manage Consent
To provide the best experiences, we use technologies like cookies to store and/or access device information. Consenting to these technologies will allow us to process data such as browsing behavior or unique IDs on this site. Not consenting or withdrawing consent, may adversely affect certain features and functions.
Functional
Always active
The technical storage or access is strictly necessary for the legitimate purpose of enabling the use of a specific service explicitly requested by the subscriber or user, or for the sole purpose of carrying out the transmission of a communication over an electronic communications network.
Preferences
The technical storage or access is necessary for the legitimate purpose of storing preferences that are not requested by the subscriber or user.
Statistics
The technical storage or access that is used exclusively for statistical purposes.The technical storage or access that is used exclusively for anonymous statistical purposes. Without a subpoena, voluntary compliance on the part of your Internet Service Provider, or additional records from a third party, information stored or retrieved for this purpose alone cannot usually be used to identify you.
Marketing
The technical storage or access is required to create user profiles to send advertising, or to track the user on a website or across several websites for similar marketing purposes.