Since syscall is outdated and broken for some architectures,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>
If the stdio of the container is owned by a group which is not mapped in
the user namespace, attempting to fchown the file descriptor will result
in EINVAL. Counteract this by simply not doing an fchown if the group
owner of the file descriptor has no host mapping according to the
configured GIDMappings.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
This enables the support for the rootless container mode. There are many
restrictions on what rootless containers can do, so many different runC
commands have been disabled:
* runc checkpoint
* runc events
* runc pause
* runc ps
* runc restore
* runc resume
* runc update
The following commands work:
* runc create
* runc delete
* runc exec
* runc kill
* runc list
* runc run
* runc spec
* runc state
In addition, any specification options that imply joining cgroups have
also been disabled. This is due to support for unprivileged subtree
management not being available from Linux upstream.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
Effectively, !dumpable makes implementing rootless containers quite
hard, due to a bunch of different operations on /proc/self no longer
being possible without reordering everything.
!dumpable only really makes sense when you are switching between
different security contexts, which is only the case when we are joining
namespaces. Unfortunately this means that !dumpable will still have
issues in this instance, and it should only be necessary to set
!dumpable if we are not joining USER namespaces (new kernels have
protections that make !dumpable no longer necessary). But that's a topic
for another time.
This also includes code to unset and then re-set dumpable when doing the
USER namespace mappings. This should also be safe because in principle
processes in a container can't see us until after we fork into the PID
namespace (which happens after the user mapping).
In rootless containers, it is not possible to set a non-dumpable
process's /proc/self/oom_score_adj (it's owned by root and thus not
writeable). Thus, it needs to be set inside nsexec before we set
ourselves as non-dumpable.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
When process config doesnt specify capabilities anywhere, we should not panic
because setting capabilities are optional.
Signed-off-by: Daniel Dao <dqminh89@gmail.com>
In container process's Init function, we use
fd + execFifoFilename to open exec fifo, so this
field in init config is never used.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
If we pass a file descriptor to the host filesystem while joining a
container, there is a race condition where a process inside the
container can ptrace(2) the joining process and stop it from closing its
file descriptor to the stateDirFd. Then the process can access the
*host* filesystem from that file descriptor. This was fixed in part by
5d93fed3d2 ("Set init processes as non-dumpable"), but that fix is
more of a hail-mary than an actual fix for the underlying issue.
To fix this, don't open or pass the stateDirFd to the init process
unless we're creating a new container. A proper fix for this would be to
remove the need for even passing around directory file descriptors
(which are quite dangerous in the context of mount namespaces).
There is still an issue with containers that have CAP_SYS_PTRACE and are
using the setns(2)-style of joining a container namespace. Currently I'm
not really sure how to fix it without rampant layer violation.
Fixes: CVE-2016-9962
Fixes: 5d93fed3d2 ("Set init processes as non-dumpable")
Signed-off-by: Aleksa Sarai <asarai@suse.de>
When signaling children and the signal is SIGKILL wait for children
otherwise conditionally wait for children which are ready to report.
This reaps all children which exited due to the signal sent without
blocking indefinitely.
Also:
* Ignore ignore ECHILD, which means the child has already gone.
Signed-off-by: Steven Hartland <steven.hartland@multiplay.co.uk>
signalAllProcesses was making the assumption that the requested signal was SIGKILL, possibly due to the signal parameter being added at a later date, and hence it was safe to wait for all processes which is not the case.
BaseContainer.Signal(s os.Signal, all bool) exposes this functionality to consumers, so an arbitrary signal could be used which is not guaranteed to make the processes exit.
Correct the documentation for signalAllProcesses around the signal delivered and update it so that the wait is only performed on SIGKILL hence making it safe to process other signals without risk of blocking forever, while still maintaining compatibility to SIGKILL callers.
Signed-off-by: Steven Hartland <steven.hartland@multiplay.co.uk>
This sets the init processes that join and setup the container's
namespaces as non-dumpable before they setns to the container's pid (or
any other ) namespace.
This settings is automatically reset to the default after the Exec in
the container so that it does not change functionality for the
applications that are running inside, just our init processes.
This prevents parent processes, the pid 1 of the container, to ptrace
the init process before it drops caps and other sets LSMs.
This patch also ensures that the stateDirFD being used is still closed
prior to exec, even though it is set as O_CLOEXEC, because of the order
in the kernel.
https://github.com/torvalds/linux/blob/v4.9/fs/exec.c#L1290-L1318
The order during the exec syscall is that the process is set back to
dumpable before O_CLOEXEC are processed.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
This allows for higher-level orchestrators to be able to have access to
the master pty file descriptor without keeping the runC process running.
This is key to having (detach && createTTY) with a _real_ pty created
inside the container, which is then sent to a higher level orchestrator
over an AF_UNIX socket.
This patch is part of the console rewrite patchset.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
Since the gid=X and mode=Y flags can be set inside config.json as mount
options, don't override them with our own defaults. This avoids
/dev/pts/* not being owned by tty in a regular container, as well as all
of the issues with us implementing grantpt(3) manually. This is the
least opinionated approach to take.
This patch is part of the console rewrite patchset.
Reported-by: Mrunal Patel <mrunalp@gmail.com>
Signed-off-by: Aleksa Sarai <asarai@suse.de>
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>
To make the code cleaner, and more clear, refactor the syncT handling
used when creating the `runc init` process. In addition, document the
state changes so that people actually understand what is going on.
Rather than only using syncT for the standard initProcess, use it for
both initProcess and setnsProcess. This removes some special cases, as
well as allowing for the use of syncT with setnsProcess.
Also remove a bunch of the boilerplate around syncT handling.
This patch is part of the console rewrite patchset.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
This allows a user to send a signal to all the processes in the
container within a single atomic action to avoid new processes being
forked off before the signal can be sent.
This is basically taking functionality that we already use being
`delete` and exposing it ok the `kill` command by adding a flag.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
This removes the use of a signal handler and SIGCONT to signal the init
process to exec the users process.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Fixes#680
This changes setupRlimit to use the Prlimit syscall (rather than
Setrlimit) and moves the call to the parent process. This is necessary
because Setrlimit would affect the libcontainer consumer if called in
the parent, and would fail if called from the child if the
child process is in a user namespace and the requested rlimit is higher
than that in the parent.
Signed-off-by: Julian Friedman <julz.friedman@uk.ibm.com>
We need to make sure the container is destroyed before closing the stdio
for the container. This becomes a big issues when running in the host's
pid namespace because the other processes could have inherited the stdio
of the initial process. The call to close will just block as they still
have the io open.
Calling destroy before closing io, especially in the host pid namespace
will cause all additional processes to be killed in the container's
cgroup. This will allow the io to be closed successfuly.
This change makes sure the order for destroy and close is correct as
well as ensuring that if any errors encoutered during start or exec will
be handled by terminating the process and destroying the container. We
cannot use defers here because we need to enforce the correct ordering
on destroy.
This also sets the subreaper setting for runc so that when running in
pid host, runc can wait on the addiontal processes launched by the
container, useful on destroy, but also good for reaping the additional
processes that were launched.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
This updates runc and libcontainer to handle rlimits per process and set
them correctly for the container.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
The re-work of namespace entering lost the setuid/setgid that was part
of the Go-routine based process exec in the prior code. A side issue was
found with setting oom_score_adj before execve() in a userns that is
also solved here.
Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
This commit adds support to libcontainer to allow caps, no new privs,
apparmor, and selinux process label to the process struct so that it can
be used together of override the base settings on the container config
per individual process.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
An init process can join other namespaces (pidns, ipc etc.). This leverages
C code defined in nsenter package to spawn a process with correct namespaces
and clone if necessary.
This moves all setns and cloneflags related code to nsenter layer, which mean
that we dont use Go os/exec to create process with cloneflags and set
uid/gid_map or setgroups anymore. The necessary data is passed from Go to C
using a netlink binary-encoding format.
With this change, setns and init processes are almost the same, which brings
some opportunity for refactoring.
Signed-off-by: Daniel, Dao Quang Minh <dqminh89@gmail.com>
[mickael.laventure@docker.com: adapted to apply on master @ d97d5e]
Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@docker.com>
Create a unique session key name for every container. Use the pattern
_ses.<postfix> with postfix being the container's Id.
This patch does not prevent containers from joining each other's session
keyring.
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.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>
Marshall the raw objects for the sync pipes so that no new line chars
are left behind in the pipe causing errors.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
For existing consumers of libconatiner to not require cwd inside the
libcontainer code. This can be done at the runc level and is already
evaluated there.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Due to the fact that the init is implemented in Go (which seemingly
randomly spawns new processes and loves eating memory), most cgroup
configurations are required to have an arbitrary minimum dictated by the
init. This confuses users and makes configuration more annoying than it
should. An example of this is pids.max, where Go spawns multiple
processes that then cause init to violate the pids cgroup constraint
before the container can even start.
Solve this problem by setting the cgroup configurations as late as
possible, to avoid hitting as many of the resources hogged by the Go
init as possible. This has to be done before seccomp rules are applied,
as the parent and child must synchronise in order for the parent to
correctly set the configurations (and writes might be blocked by seccomp).
Signed-off-by: Aleksa Sarai <asarai@suse.com>
Due to the fact that the init is implemented in Go (which seemingly
randomly spawns new processes and loves eating memory), most cgroup
configurations are required to have an arbitrary minimum dictated by the
init. This confuses users and makes configuration more annoying than it
should. An example of this is pids.max, where Go spawns multiple
processes that then cause init to violate the pids cgroup constraint
before the container can even start.
Solve this problem by setting the cgroup configurations as late as
possible, to avoid hitting as many of the resources hogged by the Go
init as possible. This has to be done before seccomp rules are applied,
as the parent and child must synchronise in order for the parent to
correctly set the configurations (and writes might be blocked by seccomp).
Signed-off-by: Aleksa Sarai <asarai@suse.com>
Whenever dev/null is used as one of the main processes STDIO, do not try
to change the permissions on it via fchown because we should not do it
in the first place and also this will fail if the container is supposed
to be readonly.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Fix the permissions of the container's main processes STDIO when the
process is not run as the root user. This changes the permissions right
before switching to the specified user so that it's STDIO matches it's
UID and GID.
Add a test for checking that the STDIO of the process is owned by the
specified user.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
This removes the existing, native Go seccomp filter generation and replaces it
with Libseccomp. Libseccomp is a C library which provides architecture
independent generation of Seccomp filters for the Linux kernel.
This adds a dependency on v2.2.1 or above of Libseccomp.
Signed-off-by: Matthew Heon <mheon@redhat.com>
Christy Perez
Aleksa Sarai
Daniel Dao
Michael Crosby
Mrunal Patel
Qiang Huang
Steven Hartland
Haiyan Meng
Petar Petrov
Julian Friedman
Phil Estes
Mrunal Patel
Stefan Berger
Aleksa Sarai
Jimmi Dyson
Alexander Morozov
Vishnu Kannan
Matthew Heon
Jin-Hwan Jeong