Limit size of various tmpfs mounts to 10% of RAM, except volatile root and /var
to 25%. Another exception is made for /dev (also /devs for PrivateDevices) and
/sys/fs/cgroup since no (or very few) regular files are expected to be used.
In addition, since directories, symbolic links, device specials and xattrs are
not counted towards the size= limit, number of inodes is also limited
correspondingly: 4MB size translates to 1k of inodes (assuming 4k each), 10% of
RAM (using 16GB of RAM as baseline) translates to 400k and 25% to 1M inodes.
Because nr_inodes option can't use ratios like size option, there's an
unfortunate side effect that with small memory systems the limit may be on the
too large side. Also, on an extremely small device with only 256MB of RAM, 10%
of RAM for /run may not be enough for re-exec of PID1 because 16MB of free
space is required.
The commit b3ac5f8cb9 has changed the system mount propagation to
shared by default, and according to the following patch:
https://github.com/opencontainers/runc/pull/208
When starting the container, the pouch daemon will call runc to execute
make-private.
However, if the systemctl daemon-reexec is executed after the container
has been started, the system mount propagation will be changed to share
again by default, and the make-private operation above will have no chance
to execute.
/dev used to be mounted with "exec" flag due to /dev/MAKEDEV script but that's
history and it's now located in /sbin. mmap() with file descriptor to
"/dev/zero" (instead of modern mmap(,,,MAP_ANON...)) will still work.
To support ProtectHome=y in a user namespace (which mounts the inaccessible
nodes), the nodes need to be accessible by the user. Create these paths and
devices in the user runtime directory so they can be used later if needed.
I want to use efivars.[ch] in proc-cmdline.c, but most of the efivars stuff is
not needed in basic/. Move the file from shared/ to basic/, but then move back
most of the higher-level functions to the new shared/efi-loader.c file.
This way less stuff needs to be in basic. Initially, I wanted to move all the
parts of cgroup-utils.[ch] that depend on efivars.[ch] to shared, because
efivars.[ch] is in shared/. Later on, I decide to split efivars.[ch], so the
move done in this patch is not necessary anymore. Nevertheless, it is still
valid on its own. If at some point we want to expose libbasic, it is better to
to not have stuff that belong in libshared there.
This function had two users (apart from tests), and both only used one
argument. And it seems likely that if we need to pass more directories,
either the _nulstr() or the _strv() form would be used. Let's simplify
the code.
relabel_extra() relabels the descendants of directories listed in
relabel-extra.d, but doesn't relabel the files or directories
explicitly named there. This makes it impossible to use
relabel-extra.d to relabel the root of a filesystem. Fix by
relabeling the named items too.
Let's generalize this, so that we can use this in nspawn later on, which
is pretty useful as we need to be able to mask files from the inner
child of nspawn too, where the host's /run/systemd/inaccessible
directory is not visible anymore. Moreover, if nspawn can create these
nodes on its own before the payload this means the payload can run with
fewer privileges.
This removes the ability to configure which cgroup controllers to mount
together. Instead, we'll now hardcode that "cpu" and "cpuacct" are
mounted together as well as "net_cls" and "net_prio".
The concept of mounting controllers together has no future as it does
not exist to cgroupsv2. Moreover, the current logic is systematically
broken, as revealed by the discussions in #10507. Also, we surveyed Red
Hat customers and couldn't find a single user of the concept (which
isn't particularly surprising, as it is broken...)
This reduced the (already way too complex) cgroup handling for us, since
we now know whenever we make a change to a cgroup for one controller to
which other controllers it applies.
These lines are generally out-of-date, incomplete and unnecessary. With
SPDX and git repository much more accurate and fine grained information
about licensing and authorship is available, hence let's drop the
per-file copyright notice. Of course, removing copyright lines of others
is problematic, hence this commit only removes my own lines and leaves
all others untouched. It might be nicer if sooner or later those could
go away too, making git the only and accurate source of authorship
information.
This part of the copyright blurb stems from the GPL use recommendations:
https://www.gnu.org/licenses/gpl-howto.en.html
The concept appears to originate in times where version control was per
file, instead of per tree, and was a way to glue the files together.
Ultimately, we nowadays don't live in that world anymore, and this
information is entirely useless anyway, as people are very welcome to
copy these files into any projects they like, and they shouldn't have to
change bits that are part of our copyright header for that.
hence, let's just get rid of this old cruft, and shorten our codebase a
bit.
Let's always write "1 << 0", "1 << 1" and so on, except where we need
more than 31 flag bits, where we write "UINT64(1) << 0", and so on to force
64bit values.
if we lack privs to create device nodes that's fine, and creating
/run/systemd/inaccessible/chr or /run/systemd/inaccessible/blk won't
work then. Document this in longer comments.
Fixes: #4484
Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.
I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.
The initial fix for relabelling the cgroup filesystem for
SELinux delivered in commit 8739f23e3 was based on the assumption that
the cgroup filesystem is already populated once mount_setup() is
executed, which was true for my system. What I wasn't aware is that this
is the case only when another instance of systemd was running before
this one, which can happen if systemd is used in the initrd (for ex. by
dracut).
In case of a clean systemd start-up the cgroup filesystem is actually
being populated after mount_setup() and does not need relabelling as at
that moment the SELinux policy is already loaded. Since however the root
cgroup filesystem was remounted read-only in the meantime this operation
will now fail.
To fix this check for the filesystem mount flags before relabelling and
only remount ro->rw->ro if necessary and leave the filesystem read-write
otherwise.
Fixes#7901.
This reworks the SELinux and SMACK label fixing calls in a number of
ways:
1. The two separate boolean arguments of these functions are converted
into a flags type LabelFixFlags.
2. The operations are now implemented based on O_PATH. This should
resolve TTOCTTOU races between determining the label for the file
system object and applying it, as it it allows to pin the object
while we are operating on it.
3. When changing a label fails we'll query the label previously set, and
if matches what we want to set anyway we'll suppress the error.
Also, all calls to label_fix() are now (void)ified, when we ignore the
return values.
Fixes: #8566
This macro will read a pointer of any type, return it, and set the
pointer to NULL. This is useful as an explicit concept of passing
ownership of a memory area between pointers.
This takes inspiration from Rust:
https://doc.rust-lang.org/std/option/enum.Option.html#method.take
and was suggested by Alan Jenkins (@sourcejedi).
It drops ~160 lines of code from our codebase, which makes me like it.
Also, I think it clarifies passing of ownership, and thus helps
readability a bit (at least for the initiated who know the new macro)
So far, for all our API VFS mounts we used the fstype also as mount
source, let's do that for the cgroupsv2 mounts too. The kernel doesn't
really care about the source for API VFS, but it's visible to the user,
hence let's clean this up and follow the rule we otherwise follow.
We make heavy use of BPF functionality these days, hence expose the BPF
file system too by default now. (Note however, that we don't actually
make use bpf file systems object yet, but we might later on too.)
When using SELinux with legacy cgroups the tmpfs on /sys/fs/cgroup is by
default labelled as tmpfs_t. This label is also inherited by the "cpu"
and "cpuacct" symbolic links. Unfortunately the policy expects them to
be labelled as cgroup_t, which is used for all the actual cgroup
filesystems. Failure to do so results in a stream of denials.
This state cannot be fixed reliably when the cgroup filesystem structure
is set-up as the SELinux policy is not yet loaded at this
moment. It also cannot be fixed later as the root of the cgroup
filesystem is remounted read-only. In order to fix it the root of the
cgroup filesystem needs to be temporary remounted read-write, relabelled
and remounted back read-only.
When systemd is running inside a container employing user
namespaces it currently mounts the unified cgroup hierarchy
without being able to write to it. This causes systemd to
freeze during boot.
This patch checks whether the unified cgroup hierarchy
is writable. If it is not it will not mount it.
This solution is based on a patch by Evgeny Vereshchagin.
Closes#6408.
Closes https://github.com/lxc/lxc/issues/1678 .
The advantage is that is the name is mispellt, cpp will warn us.
$ git grep -Ee "conf.set\('(HAVE|ENABLE)_" -l|xargs sed -r -i "s/conf.set\('(HAVE|ENABLE)_/conf.set10('\1_/"
$ git grep -Ee '#ifn?def (HAVE|ENABLE)' -l|xargs sed -r -i 's/#ifdef (HAVE|ENABLE)/#if \1/; s/#ifndef (HAVE|ENABLE)/#if ! \1/;'
$ git grep -Ee 'if.*defined\(HAVE' -l|xargs sed -i -r 's/defined\((HAVE_[A-Z0-9_]*)\)/\1/g'
$ git grep -Ee 'if.*defined\(ENABLE' -l|xargs sed -i -r 's/defined\((ENABLE_[A-Z0-9_]*)\)/\1/g'
+ manual changes to meson.build
squash! build-sys: use #if Y instead of #ifdef Y everywhere
v2:
- fix incorrect setting of HAVE_LIBIDN2
cgroup namespace wasn't useful for delegation because it allowed resource
control interface files (e.g. memory.high) to be written from inside the
namespace - this allowed the namespace parent's resource distribution to be
disturbed by its namespace-scoped children.
A new mount option, "nsdelegate", was added to cgroup v2 to address this issue.
The flag is meangingful only when mounting cgroup v2 in the init namespace and
makes a cgroup namespace a delegation boundary. The kernel feature is pending
for v4.13.
This should have been the default behavior on cgroup namespaces and this commit
makes systemd try "nsdelegate" first when trying to mount cgroup v2 and fall
back if the option is not supported.
Note that this has danger of breaking usages which depend on modifying the
parent's resource settings from the namespace root, which isn't a valid thing
to do, but such usages may still exist.
