A bit of context:
userns_exec_1() is only used to operate based on privileges for the user's own
{g,u}id on the host and for the container root's unmapped {g,u}id. This means
we require only to establish a mapping from:
- the container root {g,u}id as seen from the host -> user's host {g,u}id
- the container root -> some sub{g,u}id
This function however was buggy. It relied on some pointer pointing to the same
memory, namely specific idmap entries in the idmap list in the container's
in-memory configuration. However, due to a stupid mistake of mine, the pointers
to be compared pointed to freshly allocated memory. They were never pointing to
the intended memory locations. To reproduce what I'm talking about prior to
this commit simply place:
chb:999:1000000000
chb:999:1
chb:1000:1
in /etc/sub{g,u}id then create a container which requests the following
idmappings:
lxc.idmap = u 0 999 999
lxc.idmap = g 0 999 1000000000
and start the container. What we *would expect* is for liblxc to establish the
following mapping:
newuidmap <pid> 0 999 999
newgidmap <pid> 0 999 1000000000
since all required mappings are present. Due to the buggy pointer comparisons
what happened was:
newuidmap <pid> 0 999 999 0 999 999
newgidmap <pid> 0 999 1000000000 0 999 1000000000
Let's fix this.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
We allocate pty {master,slave} file descriptors in the childs namespaces after
we have setup devpts. After we have sent the pty file descriptors to the parent
and set up the pty file descriptors under /dev/tty* and before we exec the init
binary we need to delete these file descriptors in the child. However, one of
my commits made the deletion occur before setting up the file descriptors under
/dev/tty*. This caused a failures when trying to attach to the container's ttys
since they werent actually configured although the file descriptors were
available in the in-memory configuration of the parent.
This commit reworks setting up tty such that deletion occurs after all setup
has been performed. The commit is actually minimal but needs to also move all
the functions into one place since they well now be called from
"lxc_create_ttys()".
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
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>
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>
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>
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>
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>
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>
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>
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>
- 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>
- 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>
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>
