The motivation behind this change is to provide a flexible mechanism for
containers within a Kubernetes cluster to opt out of FIPS mode when necessary.
This change enables apps to simulate FIPS mode being enabled or disabled for testing
purposes. Users can control whether apps believe FIPS mode is on or off by manipulating
`/proc/sys/crypto/fips_enabled`.
Signed-off-by: Sohan Kunkerkar <sohank2602@gmail.com>
Our previous test for whether we can mount on top of /proc incorrectly
assumed that it would only be called with bind-mount sources. This meant
that having a non bind-mount entry for a pseudo-filesystem (like
overlayfs) with a dummy source set to /proc on the host would let you
bypass the check, which could easily lead to security issues.
In addition, the check should be applied more uniformly to all mount
types, so fix that as well. And add some tests for some of the tricky
cases to make sure we protect against them properly.
Fixes: 331692baa7af ("Only allow proc mount if it is procfs")
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
With the idmap work, we will have a tainted Go thread in our
thread-group that has a different mount namespace to the other threads.
It seems that (due to some bad luck) the Go scheduler tends to make this
thread the thread-group leader in our tests, which results in very
baffling failures where /proc/self/mountinfo produces gibberish results.
In order to avoid this, switch to using /proc/thread-self for everything
that is thread-local. This primarily includes switching all file
descriptor paths (CLONE_FS), all of the places that check the current
cgroup (technically we never will run a single runc thread in a separate
cgroup, but better to be safe than sorry), and the aforementioned
mountinfo code. We don't need to do anything for the following because
the results we need aren't thread-local:
* Checks that certain namespaces are supported by stat(2)ing
/proc/self/ns/...
* /proc/self/exe and /proc/self/cmdline are not thread-local.
* While threads can be in different cgroups, we do not do this for the
runc binary (or libcontainer) and thus we do not need to switch to
the thread-local version of /proc/self/cgroups.
* All of the CLONE_NEWUSER files are not thread-local because you
cannot set the usernamespace of a single thread (setns(CLONE_NEWUSER)
is blocked for multi-threaded programs).
Note that we have to use runtime.LockOSThread when we have an open
handle to a tid-specific procfs file that we are operating on multiple
times. Go can reschedule us such that we are running on a different
thread and then kill the original thread (causing -ENOENT or similarly
confusing errors). This is not strictly necessary for most usages of
/proc/thread-self (such as using /proc/thread-self/fd/$n directly) since
only operating on the actual inodes associated with the tid requires
this locking, but because of the pre-3.17 fallback for CentOS, we have
to do this in most cases.
In addition, CentOS's kernel is too old for /proc/thread-self, which
requires us to emulate it -- however in rootfs_linux.go, we are in the
container pid namespace but /proc is the host's procfs. This leads to
the incredibly frustrating situation where there is no way (on pre-4.1
Linux) to figure out which /proc/self/task/... entry refers to the
current tid. We can just use /proc/self in this case.
Yes this is all pretty ugly. I also wish it wasn't necessary.
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
The CAP_CHECKPOINT_RESTORE linux capability provides the ability to
update /proc/sys/kernel/ns_last_pid. However, because this file is under
/proc, and by default both K8s and CRI-O specify that /proc/sys should
be mounted as Read-Only, by default even with the capability specified,
a process will not be able to write to ns_last_pid.
To get around this, a pod author can specify a volume mount and a
hostpath to bind-mount /proc/sys/kernel/ns_last_pid. However, runc does
not allow specifying mounts under /proc.
This commit adds /proc/sys/kernel/ns_last_pid to the validProcMounts
string array to enable a pod author to mount ns_last_pid as read-write.
The default remains unchanged; unless explicitly requested as a volume
mount, ns_last_pid will remain read-only regardless of whether or not
CAP_CHECKPOINT_RESTORE is specified.
Signed-off-by: Irwin D'Souza <dsouzai.gh@gmail.com>
For files that end with _linux.go or _linux_test.go, there is no need to
specify linux build tag, as it is assumed from the file name.
In addition, rename libcontainer/notify_linux_v2.go -> libcontainer/notify_v2_linux.go
for the file name to make sense.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Fixes#2128
This allows proc to be bind mounted for host and rootless namespace usecases but
it removes the ability to mount over the top of proc with a directory.
```bash
> sudo docker run --rm apparmor
docker: Error response from daemon: OCI runtime create failed:
container_linux.go:346: starting container process caused "process_linux.go:449:
container init caused \"rootfs_linux.go:58: mounting
\\\"/var/lib/docker/volumes/aae28ea068c33d60e64d1a75916cf3ec2dc3634f97571854c9ed30c8401460c1/_data\\\"
to rootfs
\\\"/var/lib/docker/overlay2/a6be5ae911bf19f8eecb23a295dec85be9a8ee8da66e9fb55b47c841d1e381b7/merged\\\"
at \\\"/proc\\\" caused
\\\"\\\\\\\"/var/lib/docker/overlay2/a6be5ae911bf19f8eecb23a295dec85be9a8ee8da66e9fb55b47c841d1e381b7/merged/proc\\\\\\\"
cannot be mounted because it is not of type proc\\\"\"": unknown.
> sudo docker run --rm -v /proc:/proc apparmor
docker-default (enforce) root 18989 0.9 0.0 1288 4 ?
Ss 16:47 0:00 sleep 20
```
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
it is now allowed to bind mount /proc. This is useful for rootless
containers when the PID namespace is shared with the host.
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
In order to mount root filesystems inside the container's mount
namespace as part of the spec we need to have the ability to do a bind
mount to / as the destination.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
setupDev was introduced in #96, but broken since #536 because spec 0.3.0 introduced default devices.
Fix#80 again
Fixdocker/docker#21808
Signed-off-by: Akihiro Suda <suda.kyoto@gmail.com>
Signed-off-by: Alexander Morozov <lk4d4@docker.com>
