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>
Docker pkgs were updated while golinting the whole docker code base.
Now when trying to bump libcontainer/runc in docker, it fails compiling
with the following error:
``
vendor/src/github.com/opencontainers/runc/libcontainer/rootfs_linux.go:424:
undefined: mount.MountInfo
``
This is because, for instance, the mount pkg was updated here
0f5c9d301b (diff-49294d05afa48e2f7c0d2f02c6f7614c)
and now that type is only `mount.Info`.
This patch bump docker pkgs commit and adapt code to it.
Signed-off-by: Antonio Murdaca <amurdaca@redhat.com>
pivotDir is the one where pivot_root() call puts the old root. We will
unmount pivotDir() and delete it.
Previously we were making / always rslave or rprivate. That will mean
that pivotDir() could never have mounts which would be shared with
parent mount namespace. That also means that unmounting pivotDir() was
safe and none of the unmount will propagate to parent namespace and
unmount things which we did not want to.
But now user can specify that apply private, shared, slave on /. That
means some of the mounts we inherited from parent could be shared and that
also means if we umount pivotDir/, those mounts will get unmounted in
parent too. That's not what we want.
Instead make pivotDir rprivate so that unmounts don't propagate back to
parent.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
pivot_root() introduces bunch of restrictions otherwise it fails. parent
mount of container root can not be shared otherwise pivot_root() will
fail.
So far parent could not be shared as we marked everything either private
or slave. But now we have introduced new propagation modes where parent
mount of container rootfs could be shared and pivot_root() will fail.
So check if parent mount is shared and if yes, make it private. This will
make sure pivot_root() works.
Also it will make sure that when we bind mount container rootfs, it does
not propagate to parent mount namespace. Otherwise cleanup becomes a
problem.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Right now config.Privatefs is a boolean which determines if / is applied
with propagation flag syscall.MS_PRIVATE | syscall.MS_REC or not.
Soon we want to represent other propagation states like private, [r]slave,
and [r]shared. So either we can introduce more boolean variable or keep
track of propagation flags in an integer variable. Keeping an integer
variable is more versatile and can allow various kind of propagation flags
to be specified. So replace Privatefs with RootPropagation which is an
integer.
Note, this will require changes in docker. Instead of setting Privatefs
to true, they will need to set.
config.RootPropagation = syscall.MS_PRIVATE | syscall.MS_REC
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Do not remount a bind mount to enable flags unless non-default flags are
provided for the requested mount. This solves a problem with user
namespaces and remount of bind mount permissions.
Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
Do not have methods and actions that require syscalls in the configs
package because it breaks cross compile.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
We need to update the mount's destination after we resolve symlinks so
that it properly creates and mounts the correct location.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Right now if one passes a mount propagation flag in spec file, it
does not take effect. For example, try following in spec json file.
{
"type": "bind",
"source": "/root/mnt-source",
"destination": "/root/mnt-dest",
"options": "rbind,shared"
}
One would expect that /root/mnt-dest will be shared inside the container
but that's not the case.
#findmnt -o TARGET,PROPAGATION
`-/root/mnt-dest private
Reason being that propagation flags can't be passed in along with other
regular flags. They need to be passed in a separate call to mount syscall.
That too, one propagation flag at a time. (from mount man page).
Hence, store propagation flags separately in a slice and apply these
in that order after the mount call wherever appropriate. This allows
user to control the propagation property of mount point inside
the container.
Storing them separately also solves another problem where recursive flag
(syscall.MS_REC) can get mixed up. For example, options "rbind,private"
and "bind,rprivate" will be same and there will be no way to differentiate
between these if all the flags are stored in a single integer.
This patch would allow one to pass propagation flags "[r]shared,[r]slave,
[r]private,[r]unbindable" in spec file as per mount property.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
- Check if Selinux is enabled before relabeling. This is a bug.
- Make exclusion detection constant time. Kinda buggy too, imo.
- Do not depend on a magic string to create a new Selinux context.
Signed-off-by: David Calavera <david.calavera@gmail.com>
TL;DR: check for IsExist(err) after a failed MkdirAll() is both
redundant and wrong -- so two reasons to remove it.
Quoting MkdirAll documentation:
> MkdirAll creates a directory named path, along with any necessary
> parents, and returns nil, or else returns an error. If path
> is already a directory, MkdirAll does nothing and returns nil.
This means two things:
1. If a directory to be created already exists, no error is
returned.
2. If the error returned is IsExist (EEXIST), it means there exists
a non-directory with the same name as MkdirAll need to use for
directory. Example: we want to MkdirAll("a/b"), but file "a"
(or "a/b") already exists, so MkdirAll fails.
The above is a theory, based on quoted documentation and my UNIX
knowledge.
3. In practice, though, current MkdirAll implementation [1] returns
ENOTDIR in most of cases described in #2, with the exception when
there is a race between MkdirAll and someone else creating the
last component of MkdirAll argument as a file. In this very case
MkdirAll() will indeed return EEXIST.
Because of #1, IsExist check after MkdirAll is not needed.
Because of #2 and #3, ignoring IsExist error is just plain wrong,
as directory we require is not created. It's cleaner to report
the error now.
Note this error is all over the tree, I guess due to copy-paste,
or trying to follow the same usage pattern as for Mkdir(),
or some not quite correct examples on the Internet.
[1] https://github.com/golang/go/blob/f9ed2f75/src/os/path.go
Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Actually cgroup mounts are bind-mounts, so they should be
handled by the same way.
Reported-by: Ross Boucher <rboucher@gmail.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
And allow cgroup mount take flags from user configs.
As we show ro in the recommendation, so hard-coded
read-only flag should be removed.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Fixes: https://github.com/docker/docker/issues/14543
Fixes: https://github.com/docker/docker/pull/14610
Before this, we got mount info in container:
```
sysfs /sys sysfs ro,seclabel,nosuid,nodev,noexec,relatime 0 0
/sys/fs/cgroup tmpfs rw,seclabel,nosuid,nodev,noexec,relatime 0 0
cgroup /sys/fs/cgroup/cpuset cgroup rw,relatime,cpuset 0 0
```
It has no mount source, so in `parseInfoFile` in Docker code,
we'll get:
```
Error found less than 3 fields post '-' in "84 83 0:41 / /sys/fs/cgroup rw,nosuid,nodev,noexec,relatime - tmpfs rw,seclabel"
```
After this fix, we have mount info corrected:
```
sysfs /sys sysfs ro,seclabel,nosuid,nodev,noexec,relatime 0 0
tmpfs /sys/fs/cgroup tmpfs rw,seclabel,nosuid,nodev,noexec,relatime 0 0
cgroup /sys/fs/cgroup/cpuset cgroup rw,relatime,cpuset 0 0
```
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Serge Hallyn
Qiang Huang
Alexander Morozov
Abin Shahab
Antonio Murdaca
Vivek Goyal
Chun Chen
Phil Estes
Dan Walsh
Michael Crosby
Antonio Murdaca
Mrunal Patel
Andrey Vagin
rajasec
Mrunal Patel
David Calavera
Kir Kolyshkin
Alexander Morozov