When a container starts up, lxc sets up the container's inital fstree
by doing a bunch of mounting, guided by the container configuration
file.  The container config is owned by the admin or user on the host,
so we do not try to guard against bad entries.  However, since the
mount target is in the container, it's possible that the container admin
could divert the mount with symbolic links.  This could bypass proper
container startup (i.e. confinement of a root-owned container by the
restrictive apparmor policy, by diverting the required write to
/proc/self/attr/current), or bypass the (path-based) apparmor policy
by diverting, say, /proc to /mnt in the container.

To prevent this,

1. do not allow mounts to paths containing symbolic links

2. do not allow bind mounts from relative paths containing symbolic
links.

Details:

Define safe_mount which ensures that the container has not inserted any
symbolic links into any mount targets for mounts to be done during
container setup.

The host's mount path may contain symbolic links.  As it is under the
control of the administrator, that's ok.  So safe_mount begins the check
for symbolic links after the rootfs->mount, by opening that directory.

It opens each directory along the path using openat() relative to the
parent directory using O_NOFOLLOW.  When the target is reached, it
mounts onto /proc/self/fd/<targetfd>.

Use safe_mount() in mount_entry(), when mounting container proc,
and when needed.  In particular, safe_mount() need not be used in
any case where:

1. the mount is done in the container's namespace
2. the mount is for the container's rootfs
3. the mount is relative to a tmpfs or proc/sysfs which we have
   just safe_mount()ed ourselves

Since we were using proc/net as a temporary placeholder for /proc/sys/net
during container startup, and proc/net is a symbolic link, use proc/tty
instead.

Update the lxc.container.conf manpage with details about the new
restrictions.

Finally, add a testcase to test some symbolic link possibilities.

Reported-by: Roman Fiedler
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

Since we want to use null-terminated abstract sockets, let's compute the length
of them correctly.
Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

systemd wants it.  It doesn't seem to be a big deal, but it's
one fewer error msg.
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

I've noticed that a bunch of the code we've included over the past few
weeks has been using 8-spaces rather than tabs, making it all very hard
to read depending on your tabstop setting.

This commit attempts to revert all of that back to proper tabs and fix a
few more cases I've noticed here and there.

No functional changes are included in this commit.
Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>

Signed-off-by: Christian Brauner <christianvanbrauner@gmail.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

Otherwise the kernel will umount when it gets around to it, but
that on lxc_destroy we may race with it and fail the rmdir of
the overmounted (BUSY) rootfs.

This makes lxc-test-snapshot pass for me again.
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

(This *should* fix the lxc-test-snapshot testcase, but doesn't seem
to by itself.)

If it doesn't exist, we may as well start with an empty one.  This
is needed when creating an overlayfs snapshot.
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

We're asked to delete it, don't fail if it doesn't exist.

This stops lxc-destroy from failing when the container isn't fully
built.
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

Here's some more config options that we do actually require to be able to
boot containers.
Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

Closes #655

We can't rsync the delta as unpriv user because we can't create
the chardevs representing a whiteout.  We can however rsync the
rootfs and have the kernel create the whiteouts for us.

do_rsync: pass --delete
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

static do_bdev_destroy() and bdev_destroy_wrapper() from lxccontainer.c become
public bdev_destroy() and bdev_destroy_wrapper() in bdev.c and bdev.h
Signed-off-by: Christian Brauner <christianvanbrauner@gmail.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

Signed-off-by: Christian Brauner <christianvanbrauner@gmail.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

Newer kernels have added a new restriction:  if /proc or /sys on the
host has files or non-empty directories which are over-mounted, and
there is no /proc which fully visible, then it assumes there is a
"security" reason for this.  It prevents anyone in a non-initial user
namespace from creating a new proc or sysfs mount.

To work around this, this patch adds a new 'nesting.conf' which can be
lxc.include'd from a container configuration file.  It adds a
non-overmounted mount of /proc and /sys under /dev/.lxc, so that the
kernel can see that we're not trying to *hide* things like /proc/uptime.
and /sys/devices/virtual/net.  If the host adds this to the config file
for container w1, then container w1 will support unprivileged child
containers.

The nesting.conf file also sets the apparmor profile to the with-nesting
variant, since that is required anyway.  This actually means that
supporting nesting isn't really more work than it used to be, just
different.  Instead of adding

lxc.aa_profile = lxc-container-default-with-nesting

you now just need to

lxc.include = /usr/share/lxc/config/nesting.conf

(Look, fewer characters :)

Finally, in order to maintain the current apparmor protections on
proc and sys, we make /dev/.lxc/{proc,sys} non-read/writeable.
We don't need to be able to use them, we're just showing the
kernel what's what.
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

Add the description of optional, create=file/dir for lxc.mount.entry.
This is update for commit f5b67b36.
Signed-off-by: KATOH Yasufumi <karma@jazz.email.ne.jp>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

First, fix use of uninitialized variable 'ret'.  Then, actually use
the value it returned in its caller.
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>

On very busy systems, some virtual network devices won't be destroyed after a
container halts.  This patch uses the lxc_delete_network() method to ensure
that network devices attached to the container are destroyed when the
container halts.

Without the patch, some virtual network devices are left over on the system
and must be removed with `ip link del <device>`.  This caused containers
with lxc.network.veth.pair to not be able to start.  For containers using
randomly generated virtual network device names, the old devices will hang
around on the bridge with their original MAC address.
Signed-off-by: Major Hayden <major@mhtx.net>

* Remove '-P' option, and common options (including '-P' option)
* Add long option for '-f'
* Improve Japanese translation
Signed-off-by: KATOH Yasufumi <karma@jazz.email.ne.jp>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

Signed-off-by: David Noyes <david.j.noyes@gmail.com>

Signed-off-by: David Noyes <david.j.noyes@gmail.com>

Signed-off-by: David Ward <david.ward@ll.mit.edu>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

Commit 6c6892b5 "fix multithreaded create()" prevented the container
configuration from being saved if the backing store does not need
to be created.
Signed-off-by: David Ward <david.ward@ll.mit.edu>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

Use the same code with and without a rootfs to check if mounting
/proc is necessary before doing so. If mounting it is unsuccessful
and there is no rootfs, continue as before.
Signed-off-by: David Ward <david.ward@ll.mit.edu>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

A container without a rootfs is useful for running a collection of
processes in separate namespaces (to provide separate networking as
an example), while sharing the host filesystem (except for specific
paths that are re-mounted as needed). For multiple processes to run
automatically when such a container is started, it can be launched
using lxc-start, and a separate instance of systemd can manage just
the processes inside the container. (This assumes that the path to
the systemd unit files is re-mounted and only contains the services
that should run inside the container.) For this use case, autodev
should be permitted for a container that does not have a rootfs.
Signed-off-by: David Ward <david.ward@ll.mit.edu>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

Signed-off-by: David Ward <david.ward@ll.mit.edu>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

It is not an error to create a container without a template or rootfs.
Signed-off-by: David Ward <david.ward@ll.mit.edu>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

Signed-off-by: David Ward <david.ward@ll.mit.edu>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

"NAME for name of the container" becomes "NAME of the container"
Signed-off-by: Christian Brauner <christianvanbrauner@gmail.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

- Passing the LXC_CLONE_KEEPNAME flag to do_lxcapi_clone() was not respected and
  let to unexpected behaviour for e.g. lxc-clone. We wrap
  clear_unexp_config_line() and set_config_item_line() in an appropriate
  if-condition.
Signed-off-by: Christian Brauner <christianvanbrauner@gmail.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

LXC now uses lxc.cgroup.use even when cgmanager is used.
So remove the description for the case of using cgmanager.
And add the case of not specifying it.
This commit only updates en and ja man pages.
Signed-off-by: KATOH Yasufumi <karma@jazz.email.ne.jp>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

Signed-off-by: Antonio Terceiro <terceiro@debian.org>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

Signed-off-by: Antonio Terceiro <terceiro@debian.org>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

Signed-off-by: Nicolas Cornu <nicolac76@yahoo.fr>

Signed-off-by: Nicolas Cornu <ncornu@aldebaran.com>

Signed-off-by: Nicolas Cornu <ncornu@aldebaran.com>

Signed-off-by: Nicolas Cornu <ncornu@aldebaran.com>

Signed-off-by: Nicolas Cornu <ncornu@aldebaran.com>

check for NULL pointers before calling setenv()

Latest glibc release actually honours calling setenv with a NULL
pointer by causing SIGSEGV but checking pointers before submitting
to any system function is a good idea anyway.
Signed-off-by: Robert Schiele <rschiele@gmail.com>

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>