This patch fixes wrong calculation of burst_modulate(), which now calculates
the values smaller than really expected ones if available disk space is
strictly more than 1MB.
In particular, if available disk space is strictly more than 1MB and strictly
less than 16MB, the resulted value becomes smaller than its original one.
>>> (math.log2(1*1024**2)-16) / 4
1.0
>>> (math.log2(16*1024**2)-16) / 4
2.0
>>> (math.log2(256*1024**2)-16) / 4
3.0
→ This matches the comment in the function.
If ulimit is smaller than page_size(), function save_external_coredump()
returns -EBADSLT and this causes skipping whole core dumping part in
submit_coredump(). Initializing coredump_size to UINT64_MAX prevents
evaluating a condition with uninitialized varialbe which leads to
calling allocate_journal_field() with coredump_fd = -1 which causes
aborting.
Signed-off-by: Matej Habrnal <mhabrnal@redhat.com>
ProtectSystem= with all its different modes and other options like
PrivateDevices= + ProtectKernelTunables= + ProtectHome= are orthogonal,
however currently it's a bit hard to parse that from the implementation
view. Simplify it by giving each mode its own table with all paths and
references to other Protect options.
With this change some entries are duplicated, but we do not care since
duplicate mounts are first sorted by the most restrictive mode then
cleaned.
Make ALSA entries, latency interface, mtrr, apm/acpi, suspend interface,
filesystems configuration and IRQ tuning readonly.
Most of these interfaces now days should be in /sys but they are still
available through /proc, so just protect them. This patch does not touch
/proc/net/...
Move out mount calculation on its own function. Actually the logic is
smart enough to later drop nop and duplicates mounts, this change
improves code readability.
---
src/core/namespace.c | 47 ++++++++++++++++++++++++++++++++++++-----------
1 file changed, 36 insertions(+), 11 deletions(-)
Instead of having all these paths everywhere, put the ones that are
protected by ProtectKernelTunables= into their own table. This way it
is easy to add paths and track which ones are protected.
If device access is restricted via PrivateDevices=, let's also block the
various low-level I/O syscalls at the same time, so that we know that the
minimal set of devices in our virtualized /dev are really everything the unit
can access.
This adds logic to chase symlinks for all mount points that shall be created in
a namespace environment in userspace, instead of leaving this to the kernel.
This has the advantage that we can correctly handle absolute symlinks that
shall be taken relative to a specific root directory. Moreover, we can properly
handle mounts created on symlinked files or directories as we can merge their
mounts as necessary.
(This also drops the "done" flag in the namespace logic, which was never
actually working, but was supposed to permit a partial rollback of the
namespace logic, which however is only mildly useful as it wasn't clear in
which case it would or would not be able to roll back.)
Fixes: #3867
Let's create the new namespace only after we validated and processed all
parameters, right before we start with actually mounting things.
This way, the window where we can roll back is larger (not that it matters
IRL...)
If PrivateDevices=yes is set, the namespace code creates device nodes in /dev
that should be owned by the host's root, hence let's make sure we set up the
namespace before dropping group privileges.
Let's make sure that services that use DynamicUser=1 cannot leave files in the
file system should the system accidentally have a world-writable directory
somewhere.
This effectively ensures that directories need to be whitelisted rather than
blacklisted for access when DynamicUser=1 is set.
Let's tighten our sandbox a bit more: with this change ProtectSystem= gains a
new setting "strict". If set, the entire directory tree of the system is
mounted read-only, but the API file systems /proc, /dev, /sys are excluded
(they may be managed with PrivateDevices= and ProtectKernelTunables=). Also,
/home and /root are excluded as those are left for ProtectHome= to manage.
In this mode, all "real" file systems (i.e. non-API file systems) are mounted
read-only, and specific directories may only be excluded via
ReadWriteDirectories=, thus implementing an effective whitelist instead of
blacklist of writable directories.
While we are at, also add /efi to the list of paths always affected by
ProtectSystem=. This is a follow-up for
b52a109ad3 which added /efi as alternative for
/boot. Our namespacing logic should respect that too.
Previously, if ReadWritePaths= was nested inside a ReadOnlyPaths=
specification, then we'd first recursively apply the ReadOnlyPaths= paths, and
make everything below read-only, only in order to then flip the read-only bit
again for the subdirs listed in ReadWritePaths= below it.
This is not only ugly (as for the dirs in question we first turn on the RO bit,
only to turn it off again immediately after), but also problematic in
containers, where a container manager might have marked a set of dirs read-only
and this code will undo this is ReadWritePaths= is set for any.
With this patch behaviour in this regard is altered: ReadOnlyPaths= will not be
applied to the children listed in ReadWritePaths= in the first place, so that
we do not need to turn off the RO bit for those after all.
This means that ReadWritePaths=/ReadOnlyPaths= may only be used to turn on the
RO bit, but never to turn it off again. Or to say this differently: if some
dirs are marked read-only via some external tool, then ReadWritePaths= will not
undo it.
This is not only the safer option, but also more in-line with what the man page
currently claims:
"Entries (files or directories) listed in ReadWritePaths= are
accessible from within the namespace with the same access rights as
from outside."
To implement this change bind_remount_recursive() gained a new "blacklist"
string list parameter, which when passed may contain subdirs that shall be
excluded from the read-only mounting.
A number of functions are updated to add more debug logging to make this more
digestable.
This adds a new call get_user_creds_clean(), which is just like
get_user_creds() but returns NULL in the home/shell parameters if they contain
no useful information. This code previously lived in execute.c, but by
generalizing this we can reuse it in run.c.
Show is documented to be program-parseable, and printing the warning about
about a non-existent unit, while useful for humans, broke a lot of scripts.
Restore previous behaviour of returning success and printing empty or useless
stuff for units which do not exist, and printing empty values for properties
which do not exists.
With SYSTEMD_LOG_LEVEL=debug, hints are printed, but the return value is
still 0.
This undoes parts of e33a06a and 3dced37b7 and fixes#3856.
We might consider adding an explicit switch to fail on missing units/properties
(e.g. --ensure-exists or similar), and make -P foobar equivalent to
--ensure-exists --property=foobar.
While an interface is still being processed by udev, it is in state "pending",
instead of "unmanaged". We must not flush device configuration then.
Further fixes commit 3104883ddc after commit c436d55397.
Fixes#4186
Currently, systemd-sysctl command configures kernel parameters in each sysctl
configuration files in random order due to characteristics of iterator of
Hashmap.
However, kernel parameters need to be configured in the order they occur in
each sysctl configuration files.
- For example, consider fs.suid_coredump and kernel.core_pattern. If
fs.suid_coredump=2 is configured before kernel.core_pattern= whose default
value is "core", then kernel outputs the following message:
Unsafe core_pattern used with suid_dumpable=2. Pipe handler or fully qualified core dump path required.
Note that the security issue mentioned in this message has already been fixed
on recent kernels, so this is just a warning message on such kernels. But
it's still confusing to users that this message is output on some boot and
not output on another boot.
- I don't know but there could be other kernel parameters that are significant
in the order they are configured.
- The legacy sysctl command configures kernel parameters in the order they
occur in each sysctl configuration files. Although I didn't find any official
specification explaining this behavior of sysctl command, I don't think there
is any meaningful reason to change this behavior, in particular, to the
random one.
This commit does the change by simply using OrderedHashmap instead of Hashmap.
This commit is a minor tweak after the split of `--share-system`, decoupling the `--boot`
option from IPC namespacing.
Historically there has been a single `--share-system` option for sharing IPC/PID/UTS with the
host, which was incompatible with boot/pid1 mode. After the split, it is now possible to express
the requirements with better granularity.
For reference, this is a followup to #4023 which contains references to previous discussions.
I realized too late that CLONE_NEWIPC is not strictly needed for boot mode.
Since commit 5996c7c295 (v190 !), the
calculation of the HMAC is broken because the hash for a data object
including a field is done in the wrong order: the field object is
hashed before the data object is.
However during verification, the hash is done in the opposite order as
objects are scanned sequentially.
If we find duplicates in a property-lookup, make sure to order them by
their origin. That is, matches defined "later" take precedence over
earlier matches. The "later"-order is defined by file-name + line-number
combination. That is, if a match is defined below another one in the
same hwdb file, it takes precedence, same as if it is defined in a file
ordered after another one.
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Extend the hwdb to store the source file-name and file-number for each
property. We simply extend the stored value struct with the new
information. It is fully backwards compatible and old readers will
continue to work.
The libudev/sd-hwdb reader is updated in a followup.
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
It is not legal to use hard-coded types to calculate offsets. We must
always use the offsets of the hwdb header to calculate those. Otherwise,
we will break horribly if run on hwdb files written by other
implementations or written with future extensions.
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Zbigniew Jędrzejewski-Szmek
HATAYAMA Daisuke
Matej Habrnal
Torstein Husebø
Djalal Harouni
Lennart Poettering
Martin Pitt
Luca Bruno
Franck Bui
Wilhelm Schuster
David Herrmann