The documentation here:
https://docs.docker.com/engine/security/userns-remap/#user-namespace-known-limitations
says that readonly containers can't be used with user namespaces do to some
kernel restriction. In fact, there is a special case in the kernel to be
able to do stuff like this, so let's use it.
This takes us from:
ubuntu@docker:~$ docker run -it --read-only ubuntu
docker: Error response from daemon: oci runtime error: container_linux.go:262: starting container process caused "process_linux.go:339: container init caused \"rootfs_linux.go:125: remounting \\\"/dev\\\" as readonly caused \\\"operation not permitted\\\"\"".
to:
ubuntu@docker:~$ docker-runc --version
runc version 1.0.0-rc4+dev
commit: ae2948042b08ad3d6d13cd09f40a50ffff4fc688-dirty
spec: 1.0.0
ubuntu@docker:~$ docker run -it --read-only ubuntu
root@181e2acb909a:/# touch foo
touch: cannot touch 'foo': Read-only file system
Signed-off-by: Tycho Andersen <tycho@docker.com>
Since syscall is outdated and broken for some architectures,
use x/sys/unix instead.
There are still some dependencies on the syscall package that will
remain in syscall for the forseeable future:
Errno
Signal
SysProcAttr
Additionally:
- os still uses syscall, so it needs to be kept for anything
returning *os.ProcessState, such as process.Wait.
Signed-off-by: Christy Perez <christy@linux.vnet.ibm.com>
The rootless cgroup manager acts as a noop for all set and apply
operations. It is just used for rootless setups. Currently this is far
too simple (we need to add opportunistic cgroup management), but is good
enough as a first-pass at a noop cgroup manager.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
As the runtime-spec allows it, we want to be able to specify overlayfs
mounts with:
{
"destination": "/etc/pki",
"type": "overlay",
"source": "overlay",
"options": [
"lowerdir=/etc/pki:/home/amurdaca/go/src/github.com/opencontainers/runc/rootfs_fedora/etc/pki"
]
},
This patch takes care of allowing overlayfs mounts. Both RO and RW
should be supported.
Signed-off-by: Antonio Murdaca <runcom@redhat.com>
On some systems, when we mount some cgroup subsystems into
a same mountpoint, the name sequence of mount options and
cgroup directory name can not be the same.
For example, the mount option is cpuacct,cpu, but
mountpoint name is /sys/fs/cgroup/cpu,cpuacct. In current
runc, we set mount destination name from combining
subsystems, which comes from mount option from
/proc/self/mountinfo, so in my case the name would be
/sys/fs/cgroup/cpuacct,cpu, which is differernt from
host, and will break some applications.
Fix it by using directory name from host mountpoint.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
A remount of a mount point must include all the current flags or
these will be cleared:
```
The mountflags and data arguments should match the values used in the
original mount() call, except for those parameters that are being
deliberately changed.
```
The current code does not do this; the bug manifests in the specified
flags for `/dev` being lost on remount read only at present. As we
need to specify flags, split the code path for this from remounting
paths which are not mount points, as these can only inherit the
existing flags of the path, and these cannot be changed.
In the bind case, remove extra flags from the bind remount. A bind
mount can only be remounted read only, no other flags can be set,
all other flags are inherited from the parent. From the man page:
```
Since Linux 2.6.26, this flag can also be used to make an existing
bind mount read-only by specifying mountflags as:
MS_REMOUNT | MS_BIND | MS_RDONLY
Note that only the MS_RDONLY setting of the bind mount can be changed
in this manner.
```
MS_REC can only be set on the original bind, so move this. See note
in man page on bind mounts:
```
The remaining bits in the mountflags argument are also ignored, with
the exception of MS_REC.
```
Signed-off-by: Justin Cormack <justin.cormack@docker.com>
This implements {createTTY, detach} and all of the combinations and
negations of the two that were previously implemented. There are some
valid questions about out-of-OCI-scope topics like !createTTY and how
things should be handled (why do we dup the current stdio to the
process, and how is that not a security issue). However, these will be
dealt with in a separate patchset.
In order to allow for late console setup, split setupRootfs into the
"preparation" section where all of the mounts are created and the
"finalize" section where we pivot_root and set things as ro. In between
the two we can set up all of the console mountpoints and symlinks we
need.
We use two-stage synchronisation to ensures that when the syscalls are
reordered in a suboptimal way, an out-of-place read() on the parentPipe
will not gobble the ancilliary information.
This patch is part of the console rewrite patchset.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
I use the same tool (https://github.com/client9/misspell)
as Daniel used a few days ago, don't why he missed these
typos at that time.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
This reverts part of the commit eb0a144b5e
That commit introduced two issues.
- We need to make parent mount of rootfs private before bind mounting
rootfs. Otherwise bind mounting root can propagate in other mount
namespaces. (If parent mount is shared).
- It broke test TestRootfsPropagationSharedMount() on Fedora.
On fedora /tmp is a mount point with "shared" propagation. I think
you should be able to reproduce it on other distributions as well
as long as you mount tmpfs on /tmp and make it "shared" propagation.
Reason for failure is that pivot_root() fails. And it fails because
kernel does following check.
IS_MNT_SHARED(new_mnt->mnt_parent)
Say /tmp/foo is new rootfs, we have bind mounted rootfs, so new_mnt
is /tmp/foo, and new_mnt->mnt_parent is /tmp which is "shared" on
fedora and above check fails.
So this change broke few things, it is a good idea to revert part of it.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Namely, use an undocumented feature of pivot_root(2) where
pivot_root(".", ".") is actually a feature and allows you to make the
old_root be tied to your /proc/self/cwd in a way that makes unmounting
easy. Thanks a lot to the LXC developers which came up with this idea
first.
This is the first step of many to allowing runC to work with a
completely read-only rootfs.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
If copyup is specified for a tmpfs mount, then the contents of the
underlying directory are copied into the tmpfs mounted over it.
Signed-off-by: Mrunal Patel <mrunalp@gmail.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>
For example, the /sys/firmware directory should be masked because it can contain some sensitive files:
- /sys/firmware/acpi/tables/{SLIC,MSDM}: Windows license information:
- /sys/firmware/ibft/target0/chap-secret: iSCSI CHAP secret
Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>
There's no point in changing directory here. Syscalls are resolved local
to the linkpath, not to the current directory that the process was in
when creating the symlink. Changing directories just confuses people who
are trying to debug things.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
Comparisons with paths aren't really a good idea unless you're
guaranteed that the comparison will work will all paths that resolve to
the same lexical path as the compared path.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
This is the inital port of the libcontainer.Error to added a cause to
all the existing error messages. Going forward, when an error can be
wrapped because it is not being checked at the higher levels for
something like `os.IsNotExist` we can add more information to the error
message like cause and stack file/line information. This will help
higher level tools to know what cause a container start or operation to
fail.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
No substantial code change.
Note that some style errors reported by `golint` are not fixed due to possible compatibility issues.
Signed-off-by: Akihiro Suda <suda.kyoto@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>
This allows the mount syscall to validate the addiontal types where we
do not have to perform extra validation and is up to the consumer to
verify the functionality of the type of device they are trying to
mount.
Fixes#572
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Signed-off-by: rajasec <rajasec79@gmail.com>
Changing to name values for defer as per review comments
Signed-off-by: rajasec <rajasec79@gmail.com>
Fixed review comments
Signed-off-by: rajasec <rajasec79@gmail.com>
Because we more than likely control dev and populate devices and files
inside of it we need to make sure that we fulfil the user's request to
make it ro only after it has been populated. This removes the need to
expose something like ReadonlyPaths in the config but still have the
same outcome but more seemless for the user.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Today mounts in pre-start hooks get overriden by the default mounts.
Moving the pre-start hooks to after the container mounts and before
the pivot/move root gives better flexiblity in the hooks.
Signed-off-by: Mrunal Patel <mrunalp@gmail.com>
When we launch a container in a new user namespace, we cannot create
devices, so we bind mount the host's devices into place instead.
If we are running in a user namespace (i.e. nested in a container),
then we need to do the same thing. Add a function to detect that
and check for it before doing mknod.
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
---
Changelog - add a comment clarifying what's going on with the
uidmap file.
Enables launching userns containers by catching EPERM errors for writing
to devices cgroups, and for mknod invocations.
Signed-off-by: Abin Shahab <ashahab@altiscale.com>
Minor fix, the former setupDev=true means not setup dev,
which is contrary to intuition, just correct it.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Tycho Andersen
Christy Perez
Qiang Huang
Daniel, Dao Quang Minh
Aleksa Sarai
Ma Shimiao
Antonio Murdaca
Justin Cormack
Vivek Goyal
Alexander Morozov
Mrunal Patel
Michael Crosby
Akihiro Suda
Serge Hallyn
Haiyan Meng
Aleksa Sarai
Dan Walsh
Tatsushi Inagaki
Akihiro Suda
Thomas Tanaka
Mrunal Patel
rajasec
Chun Chen
Kenfe-Mickael Laventure
Serge Hallyn
Abin Shahab