The idea was to make them strict on dest path from the beginning for
idmap mounts, as runc would do that for all mounts in the future. But
that is causing too many problems.
For now, let's just allow relative paths for idmap mounts too. It just
seems safer.
Signed-off-by: Rodrigo Campos <rodrigoca@microsoft.com>
This reverts commit 881e92a3fd and adjust
the code so the idmap validations are strict.
We now only throw a warning and the container is started just fine.
Signed-off-by: Rodrigo Campos <rodrigoca@microsoft.com>
This commit does two things:
1. Consolidate StartInitialization calling logic into Init().
2. Fix init error handling logic.
The main issues at hand are:
- the "unable to convert _LIBCONTAINER_INITPIPE" error from
StartInitialization is never shown;
- errors from WriteSync and WriteJSON are never shown;
- the StartInit calling code is triplicated;
- using panic is questionable.
Generally, our goals are:
- if there's any error, do our best to show it;
- but only show each error once;
- simplify the code, unify init implementations.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Currently, logrus is used from the Go part of runc init, mostly for a
few debug messages (see setns_init_linux.go and standard_init_linux.go),
and a single warning (see rootfs_linux.go).
This means logrus is part of init implementation, and thus, its setup
belongs to StartInitialization().
Move the code there. As a nice side effect, now we don't have to convert
_LIBCONTAINER_LOGPIPE twice.
Note that since this initialization is now also called from libct/int
tests, which do not set _LIBCONTAINER_LOGLEVEL, let's make
_LIBCONTAINER_LOGLEVEL optional.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
With the new vm.memfd_noexec sysctl, we need to make sure we explicitly
request MFD_EXEC, otherwise an admin could inadvertently break
containers in a somewhat-annoying-to-debug fashion.
It should be noted that vm.memfd_noexec=2 is broken on Linux 6.4
(MFD_EXEC works even in the most restrictive mode) and the most severe
breakage is going to be fixed in Linux 6.6[1].
[1]: https://lore.kernel.org/20230705063315.3680666-2-jeffxu@google.com/
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
While the ro-bind-mount trick did eliminate the memory overhead of
copying the runc binary for each "runc init" invocation, on machines
with very significant container churn, creating a temporary mount
namespace on every container invocation can trigger severe lock
contention on namespace_sem that makes containers fail to spawn.
The only reason we added bindfd in commit 16612d74de ("nsenter:
cloned_binary: try to ro-bind /proc/self/exe before copying") was due to
a Kubernetes e2e test failure where they had a ridiculously small memory
limit. It seems incredibly unlikely that real workloads are running
without 10MB to spare for the very short time that runc is interacting
with the container.
In addition, since the original cloned_binary implementation, cgroupv2
is now almost universally used on modern systems. Unlike cgroupv1, the
cgroupv2 memcg implementation does not migrate memory usage when
processes change cgroups (even cgroupv1 only did this if you had
memory.move_charge_at_immigrate enabled). In addition, because we do the
/proc/self/exe clone before synchronising the bootstrap data read, we
are guaranteed to do the clone before "runc init" is moved into the
container cgroup -- meaning that the memory used by the /proc/self/exe
clone is charged against the root cgroup, and thus container workloads
should not be affected at all with memfd cloning.
The long-term fix for this problem is to block the /proc/self/exe
re-opening attack entirely in-kernel, which is something I'm working
on[1]. Though it should also be noted that because the memfd is
completely separate to the host binary, even attacks like Dirty COW
against the runc binary can be defended against with the memfd approach.
Of course, once we have in-kernel protection against the /proc/self/exe
re-opening attack, we won't have that protection anymore...
[1]: https://lwn.net/Articles/934460/
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
As we now log the log file name in logCriuErrors.
While at it, there is no need to use var.String() with %s as it is done
by the runtime.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
When criu fails, it does not give us much context to understand what
was the cause of an error -- for that, we need to take a look into its
log file.
This is somewhat complicated to do (as you can see in parts of
checkpoint.bats removed by this commit), and not very user-friendly.
Add a function to find and log errors from criu logs, together with some
preceding context, in case either checkpoint or restore has failed.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
A few cases relied on the fact that systemd is used, and thus
/sys/fs/cgroup/user.slice is available.
Guess what, in case of "make unittest" it might not be.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Split the test into two -- for fs and systemd cgroup managers, and only
run the second one if systemd is available.
Prevents the following failure during `make unittest`:
> === RUN TestNilResources
> manager_test.go:27: systemd not running on this host, cannot use systemd cgroups manager
> --- FAIL: TestNilResources (0.22s)
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
"time" namespace was introduced in Linux v5.6
support new time namespace to set boottime and monotonic time offset
Example runtime spec
"timeOffsets": {
"monotonic": {
"secs": 172800,
"nanosecs": 0
},
"boottime": {
"secs": 604800,
"nanosecs": 0
}
}
Signed-off-by: Chethan Suresh <chethan.suresh@sony.com>
This aligns v2 usage calculations more closely with v1.
Current node-level reporting for v1 vs v2 on the same
machine under similar load may differ by ~250-750Mi.
Also return usage as combined swap + memory usage, aligned
with v1 and non-root v2 cgroups.
`mem_cgroup_usage` in the kernel counts NR_FILE_PAGES
+ NR_ANON_MAPPED + `nr_swap_pages` (if swap enabled) [^0].
Using total - free results in higher "usage" numbers.
This is likely due to various types of reclaimable
memory technically counted as in use (e.g. inactive anon).
See also https://github.com/kubernetes/kubernetes/issues/118916 for more context
[^0]: https://github.com/torvalds/linux/blob/06c2afb862f9da8dc5efa4b6076a0e48c3fbaaa5/mm/memcontrol.c#L3673-L3680
Signed-off-by: Alexander Eldeib <alexeldeib@gmail.com>
close_range(2) is far more efficient than a readdir of /proc/self/fd and
then doing a syscall for each file descriptor.
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
While testing this with old kernel versions and kernels that don't
support idmap mounts for some of the filesystems used by a container, I
realized we can throw a more clear errors.
Let's make it clear which syscall we are using, when it is not supported
and when if the fs doesn't support idmap mounts, which path it is.
Signed-off-by: Rodrigo Campos <rodrigoca@microsoft.com>
Since systemd v240 (commit 8e8b5d2e6d91180a), one can use
/dev/{char,block}-MAJOR syntax to specify that all MAJOR:*
devices are allowed.
Use it, if available, since it's more straightforward, plus
we can skip somewhat expensive parsing of /proc/devices.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Currently bind mounts of filesystems with nodev, nosuid, noexec,
noatime, relatime, strictatime, nodiratime options set fail in rootless
mode if the same options are not set for the bind mount.
For ro filesystems this was resolved by #2570 by remounting again
with ro set.
Follow the same approach for nodev, nosuid, noexec, noatime, relatime,
strictatime, nodiratime but allow to revert back to the old behaviour
via the new `--no-mount-fallback` command line option.
Add a testcase to verify that bind mounts of filesystems with nodev,
nosuid, noexec, noatime options set work in rootless mode.
Add a testcase that mounts a nodev, nosuid, noexec, noatime filesystem
with a ro flag.
Add two further testcases that ensure that the above testcases would
fail if the `--no-mount-fallback` command line option is set.
* contrib/completions/bash/runc:
Add `--no-mount-fallback` command line option for bash completion.
* create.go:
Add `--no-mount-fallback` command line option.
* restore.go:
Add `--no-mount-fallback` command line option.
* run.go:
Add `--no-mount-fallback` command line option.
* libcontainer/configs/config.go:
Add `NoMountFallback` field to the `Config` struct to store
the command line option value.
* libcontainer/specconv/spec_linux.go:
Add `NoMountFallback` field to the `CreateOpts` struct to store
the command line option value and store it in the libcontainer
config.
* utils_linux.go:
Store the command line option value in the `CreateOpts` struct.
* libcontainer/rootfs_linux.go:
In case that `--no-mount-fallback` is not set try to remount the
bind filesystem again with the options nodev, nosuid, noexec,
noatime, relatime, strictatime or nodiratime if they are set on
the source filesystem.
* tests/integration/mounts_sshfs.bats:
Add testcases and rework sshfs setup to allow specifying
different mount options depending on the test case.
Signed-off-by: Ruediger Pluem <ruediger.pluem@vodafone.com>
We cannot have both srcFD and idMapFD set at the same time.
So, we can simplify this struct to only have one field which is used a srcFD
most of the time and as idMapFD when we do an id map mount.
Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
Previously to this commit, we used a string for srcFD as /proc/self/fd/NN.
This commit modified to this behavior, so srcFD is only an *int and the full path
is constructed in mountViaFDs() if srcFD is different than nil.
Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
This commit adds support for idmap mounts as specified in the runtime-spec.
We open the idmap source paths and call mount_setattr() in runc PARENT,
as we need privileges in the init userns for that, and then sends the
fds to the child process. For this fd passing we use the same mechanism
used in other parts of thecode, the _LIBCONTAINER_ env vars.
The mount is finished (unix.MoveMount) from go code, inside the userns,
so we reuse all the prepareBindMount() security checks and the remount
logic for some flags too.
This commit only supports idmap mounts when userns are used AND the mappings
are the same specified for the userns mapping. This limitation is to
simplify the initial implementation, as all our users so far only need
this, and we can avoid sending over netlink the mappings, creating a
userns with this custom mapping, etc. Future PRs will remove this
limitation.
Co-authored-by: Francis Laniel <flaniel@linux.microsoft.com>
Signed-off-by: Rodrigo Campos <rodrigoca@microsoft.com>
We will need to pass more slices of fds to these functions in future
patches. Let's add a struct that just contains them all, instead of
adding lot of parameters to these functions.
Signed-off-by: Rodrigo Campos <rodrigoca@microsoft.com>
We will add code that uses this function in future patches. So let's
just split it to a new function now and reuse it later.
Signed-off-by: Rodrigo Campos <rodrigoca@microsoft.com>
Let's move the code to send mount sources to a generic function. Future
patches will use it for idmap sources too.
Signed-off-by: Rodrigo Campos <rodrigoca@microsoft.com>
We add idmap.h with the needed includes and defines in case the system
headers don't have the definition for the idmap syscalls we need.
Future patches will use these helpers.
Co-authored-by: Francis Laniel <flaniel@linux.microsoft.com>
Signed-off-by: Rodrigo Campos <rodrigoca@microsoft.com>
We just added this helper for other parts of the code, let's switch this
function to use the helper too.
Signed-off-by: Rodrigo Campos <rodrigoca@microsoft.com>
This was a warning already and it was requested to make this an error
while we will add validation of idmap mounts:
https://github.com/opencontainers/runc/pull/3717#discussion_r1154705318
I've also tested a k8s cluster and the config.json generated by
containerd didn't use any relative paths. I tested one pod, so it was
definitely not an extensive test.
Signed-off-by: Rodrigo Campos <rodrigoca@microsoft.com>
Processes can watch /proc/self/mounts or /mountinfo, and the kernel
will notify them whenever the namespace's mount table is modified. The
notified process still needs to read and parse the mountinfo to
determine what changed once notified. Many such processes, including
udisksd and SystemD < v248, make no attempt to rate-limit their
mountinfo notifications. This tends to not be a problem on many systems,
where mount tables are small and mounting and unmounting is uncommon.
Every runC exec which successfully uses the try_bindfd container-escape
mitigation performs two mount()s and one umount() in the host's mount
namespace, causing any mount-watching processes to wake up and parse the
mountinfo file three times in a row. Consequently, using 'exec' health
checks on containers has a larger-than-expected impact on system load
when such mount-watching daemons are running. Furthermore, the size of
the mount table in the host's mount namespace tends to be proportional
to the number of OCI containers as a unique mount is required for the
rootfs of each container. Therefore, on systems with mount-watching
processes, the system load increases *quadratically* with the number of
running containers which use health checks!
Prevent runC from incidentally modifying the host's mount namespace for
container-escape mitigations by setting up the mitigation in a temporary
mount namespace.
Signed-off-by: Cory Snider <csnider@mirantis.com>
Modify receive_fd() and send_fd() so they can be more readily reused in
cloned_binary.c. Change receive_fd() to have a single responsibility:
receiving and returning a single file descriptor over a UNIX domain
socket. Make send_fd() useable in precarious execution contexts such as
a clone(CLONE_VFORK|CLONE_VM) "thread" where allocating heap memory or
calling exit() would be dangerous.
Signed-off-by: Cory Snider <csnider@mirantis.com>
runc delete is supposed to remove all the container's artefacts.
In case systemd cgroup driver is used, and the systemd unit has failed
(e.g. oom-killed), systemd won't remove the unit (that is, unless the
"CollectMode: inactive-or-failed" property is set).
Call reset-failed from manager.Destroy so the failed unit will be
removed during "runc delete".
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Sometimes we call resetFailedUnit as a cleanup measure, and we don't
care if it fails or not. So, move error reporting to its callers, and
ignore error in cases we don't really expect it to succeed.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Aleksa Sarai