criu: add cmp_version()

We cannot use strcmp(). Otherwise we incorrectly report e.g. that criu 2.12.1
is less than 2.8.
Signed-off-by: Federico Briata <federico-pietro.briata@cnhind.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

console: non-functional change

conf: don't send ttys when none are configured

It is bad style to close an fd inside a function which didn't create it. Let's
rather close it transparently in start.c.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

network: improvements + bugfixes

Writes < PIPE_BUF will be atomic. PIPE_BUF is guaranteed to be 512 by POSIX and
Linux guarantess 4096. Nothing we send around goes over this limit.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

I thought we could send all ttys at once but this limits the number of ttys
users can use because of iovec_len restrictions. So let's sent them in batches
of 2.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

lxc_mkifname() really doesn't need to allocate any memory.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Also move all functions to network.{c,h}.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Since find_line() was changed before count_entries() started counting lines
wrong. It would report maximum reached before you actually reached your alloted
maximum.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Assume the db contained the following entries:

    chb veth lxcbr0 veth1
    chb veth lxcbr0 veth2
    chb veth lxdbr0 veth3
    chb veth lxdbr0 veth2
    didi veth lxcbr0 veth4

And you request

    cull_entries("chb", "veth", "lxdbr0", "veth3");

lxc-user-nic would wipe any entries that did not match irrespective of whether
they existed or not. Let's fix that.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

The code before inserted \0-bytes after every new line which made the db
basically unusable.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

We use data_sock for all things we need to send around between parent and child
now. It doesn't make sense to have so many different pipes and sockets if one
will do just fine.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Signed-off-by: Dimitri John Ledkov <xnox@ubuntu.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

If netplan is present in the container, configure default networking
with neplan instead of ifupdown. Also, do not install ifupdown when
boostrapping minbase variant, unless using currently support
non-netplan releases (trusty, zenial, zesty).
Signed-off-by: Dimitri John Ledkov <xnox@ubuntu.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

liblxc will now correctly log any network device names and ifindeces in their
respective network namespaces. So there's no need to record physical network
devices any more. This spares us heap allocations and memory we need to have
lying around til the container is shutdown.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

On privileged network creation we only retrieved the names and ifindeces of
network devices in the host's network namespace. This meant that the monitor
process was acting on possibly incorrect information. With this commit we have
the child send back the correct device names and ifindeces in the container's
network namespace.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

This renames the socketpair() variable "ttysock" to "data_sock" since we will
use it to send arbitrary data around, not just ttys anymore.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

All network devices can only be of size < IFNAMSIZ. So let's spare the useless
heap allocations and use static memory.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

- check for error on ifindex retrieval
- free allocated memory
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

- Retrieve the host's veth device ifindex in the host's network namespace.
- Add a note why we retrieve the container's veth device ifindex in the host's
  network namespace.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

lxc-user-nic: test privilege over netns on delete

- On unprivileged veth network creation have lxc-user-nic send the names of the
  veth devices and their respective ifindeces. The advantage of retrieving this
  information from lxc-user-nic is that we spare us sending around more stuff
  via the netpipe in start.c. Also, lxc-user-nic operates in both namespaces
  (the container's namespace and the hosts's namespace) via setns and so is
  guaranteed to retrieve the correct ifindex via if_nametoindex() which is an
  network namespace aware ioctl() call. While I'm pretty sure the ifindeces for
  veth devices are identical across network namespaces I'm weary to rely on
  this. We need the ifindexes to guarantee safe deletion of unprivileged
  network devices via lxc-user-nic later on since we use them to identify the
  network devices in their corresponding network namespaces.
- Move the network device logging from the child to the parent. The child does
  not have all of the information about the network devices available only the
  few bits it actually needs to now. The monitor process is the only process
  that needs all this information.
- The network creation code for privileged and unprivileged networks was
  previously mangled into one single function but at the same time some of the
  privileged code had additional functions that were called in other places in
  start.c. Let's divide and conquer and split out the privileged and
  unprivileged network creation into completely separate functions. This makes
  what's happening way more clear. This will also have no performance impact
  since either you are privileged and only execute the privileged network
  creation functions or you are unprivileged and only execute the unprivileged
  network creation functions.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

This is menial work but I'll thank myself later... a lot.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

We should not just record the ifindex for the container's veth device but also
for the host's veth device. This is useful when {configuring,deconfiguring}
veth devices and becomes crucial when calling our lxc-user-nic setuid helper
where we rely on the ifindex to make decisions about whether we are licensed to
perform certain operations on the veth device in question.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

If the user specified lxc.net.[i].veth.pair attribute to request that the host
side of a veth pair be given a specific name let's log it at the trace level.
Otherwise, if the user didn't not specify lxc.net.[i].veth.pair veth_attr.veth1
will contain the name of the host side veth device.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

When lxc-user-nic is called with the "delete" subcommand we need to make sure
that we are actually privileged over the network namespace for which we are
supposed to delete devices on the host. To this end we require that path to the
affected network namespace is passed. We then setns() to the network namespace
and drop privilege to the caller's real user id. Then we try to delete the
loopback interface which is not possible. If we are privileged over the network
namespace this operation will fail with ENOTSUP. If we are not privileged over
the network namespace we will get EPERM.

This is the first part of the commit. As of now nothing guarantees that the
caller does not just give us a random path to a network namespace it is
privileged over.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

This is the cause of the unnecessary extraneous slashes when creating cgroups.
Our lxc.system.conf page also clearly shows "lxc/%n" as example, not "/lxc%n".
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Remove executable bit.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>