Let's be safe, rather than sorry. This way DynamicUser=yes services can
neither take benefit of, nor create SUID/SGID binaries.
Given that DynamicUser= is a recent addition only we should be able to
get away with turning this on, even though this is strictly speaking a
binary compatibility breakage.
"BOOT" is misleading, because it sounds like this refers to /boot or $BOOT,
when in fact it refers to some subdirectory. Those variable names are purely
interal, so we can change them. $BOOT_DIR_ABS was used in NEWS, but it should
not be (because it is an internal detail), so the old NEWS entry is reworded to
use "entry directory".
Previously, this system call was included in @system-service since it is
a "getter" only, i.e. only queries information, and doesn't change
anything, and hence was considered not risky.
However, as it turns out, mincore() is actually security sensitive, see
the discussion here:
https://lwn.net/Articles/776034/
Hence, let's adjust the system call filter and drop mincore() from it.
This constitues a compatibility break to some level, however I presume
we can get away with this as the systemcall is pretty exotic. The fact
that it is pretty exotic is also reflected by the fact that the kernel
intends to majorly change behaviour of the system call soon (see the
linked LWN article)
These sysctls were added in Linux 4.19 (torvalds/linux@30aba6656f), and
we should enable them just like we enable the older hardlink/symlink
protection since v199. Implements #11414.
Nitpicky, but we've used a lot of random spacings and names in the past,
but we're trying to be completely consistent on "cgroup vN" now.
Generated by `fd -0 | xargs -0 -n1 sed -ri --follow-symlinks 's/cgroups? ?v?([0-9])/cgroup v\1/gI'`.
I manually ignored places where it's not appropriate to replace (eg.
"cgroup2" fstype and in src/shared/linux).
This reverts commit edda44605f.
The kernel explicitly supports resuming with a different kernel than the one
used before hibernation. If this is something that shouldn't be supported, the
place to change this is in the kernel. We shouldn't censor something that this
exclusively in the kernel's domain.
People might be using this to switch kernels without restaring programs, and
we'd break this functionality for them.
Also, even if resuming with a different kernel was a bad idea, we don't really
prevent that with this check, since most users have more than one kernel and
can freely pick a different one from the menu. So this only affected the corner
case where the kernel has been removed, but there is no reason to single it
out.
From WordNet (r) 3.0 (2006) [wn]:
time-out
n 1: a brief suspension of play; "each team has two time-outs left"
From The Free On-line Dictionary of Computing (18 March 2015) [foldoc]:
timeout
A period of time after which an error condition is raised if
some event has not occured. A common example is sending a
message. If the receiver does not acknowledge the message
within some preset timeout period, a transmission error is
assumed to have occured.
This switches the RFC3704 Reverse Path filtering from Strict mode to Loose
mode. The Strict mode breaks some pretty common and reasonable use cases,
such as keeping connections via one default route alive after another one
appears (e.g. plugging an Ethernet cable when connected via Wi-Fi).
The strict filter also makes it impossible for NetworkManager to do
connectivity check on a newly arriving default route (it starts with a
higher metric and is bumped lower if there's connectivity).
Kernel's default is 0 (no filter), but a Loose filter is good enough. The
few use cases where a Strict mode could make sense can easily override
this.
The distributions that don't care about the client use cases and prefer a
strict filter could just ship a custom configuration in
/usr/lib/sysctl.d/ to override this.
After discussions with kernel folks, a system with memcg really
shouldn't need extra hard limits on file descriptors anymore, as they
are properly accounted for by memcg anyway. Hence, let's bump these
values to their maximums.
This also adds a build time option to turn thiss off, to cover those
users who do not want to use memcg.
Lennart Poettering