Technically, this change should not be necessary, as the kernel
documentation claims that if you call clone(flags|CLONE_NEWUSER), the
new user namespace will be the owner of all other namespaces created in
@flags. Unfortunately this isn't always the case, due to various
additional semantics and kernel bugs.
One particular instance is SELinux, which acts very strangely towards
the IPC namespace and mqueue. If you unshare the IPC namespace *before*
you map a user in the user namespace, the IPC namespace's internal
kern-mount for mqueue will be labelled incorrectly and the container
won't be able to access it. The only way of solving this is to unshare
IPC *after* the user has been mapped and we have changed to that user.
I've also heard of this happening to the NET namespace while talking to
some LXC folks, though I haven't personally seen that issue.
This change matches our handling of user namespaces to be the same as
how LXC handles these problems.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
With the addition of our new{uid,gid}map support, we used to call
execvp(3) from inside nsexec. This would mean that the path resolution
for the binaries would happen in nsexec. Move the resolution to the
initial setup code, and pass the absolute path to nsexec.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
After quite a bit of debugging, I found that previous versions of this
patchset did not include newgidmap in a rootless setting. Fix this by
passing it whenever group mappings are applied, and also providing some
better checking for try_mapping_tool. This commit also includes some
stylistic improvements.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
Take advantage of the newuidmap/newgidmap tools to allow multiple
users/groups to be mapped into the new user namespace in the rootless
case.
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
[ rebased to handle intelrdt changes. ]
Signed-off-by: Aleksa Sarai <asarai@suse.de>
This allows the libcontainer to automatically clean up runc:[1:CHILD]
processes created as part of nsenter.
Signed-off-by: Alex Fang <littlelightlittlefire@gmail.com>
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>
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 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>
config.cloneflag is not mandatory, when using `runc exec`,
config.cloneflag can be empty, and even then it won't be
`-1` but `0`.
So this validation is totally wrong and unneeded.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Without this patch applied, RHEL's SELinux policies cause container
creation to not really work. Unfortunately this might be an issue for
rootless containers (opencontainers/runc#774) but we'll cross that
bridge when we come to it.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
Depending on your SELinux setup, the order in which you join namespaces
can be important. In general, user namespaces should *always* be joined
and unshared first because then the other namespaces are correctly
pinned and you have the right priviliges within them. This also is very
useful for rootless containers, as well as older kernels that had
essentially broken unshare(2) and clone(2) implementations.
This also includes huge refactorings in how we spawn processes for
complicated reasons that I don't want to get into because it will make
me spiral into a cloud of rage. The reasoning is in the giant comment in
clone_parent. Have fun.
In addition, because we now create multiple children with CLONE_PARENT,
we cannot wait for them to SIGCHLD us in the case of a death. Thus, we
have to resort to having a child kindly send us their exit code before
they die. Hopefully this all works okay, but at this point there's not
much more than we can do.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
This avoids us from running into cases where libcontainer thinks that a
particular namespace file is a different type, and makes it a fatal
error rather than causing broken functionality.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
This just moves everything to one function so we don't have to pass a
bunch of things to functions when there's no real benefit. It also makes
the API nicer.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
Removed a lot of clutter, improved the style of the code, removed
unnecessary complexity. In addition, made errors unique by making bail()
exit with a unique error code. Most of this code comes from the current
state of the rootless containers branch.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
Fix the following warnings when building runc with gcc 6+:
Godeps/_workspace/src/github.com/opencontainers/runc/libcontainer/nsenter/nsexec.c:
In function ‘nsexec’:
Godeps/_workspace/src/github.com/opencontainers/runc/libcontainer/nsenter/nsexec.c:322:6:
warning: ‘__s’ may be used uninitialized in this function
[-Wmaybe-uninitialized]
pr_perror("Failed to open %s", ns);
Godeps/_workspace/src/github.com/opencontainers/runc/libcontainer/nsenter/nsexec.c:273:30:
note: ‘__s’ was declared here
static struct nsenter_config process_nl_attributes(int pipenum, char
*data, int data_size)
^~~~~~~~~~~~~~~~~~~~~
Signed-off-by: Antonio Murdaca <runcom@redhat.com>
Remove a wrongly added include which was added in commit 3c2e77ee (Add a
compatibility header for CentOS/RHEL 6, 2016-01-29) apparently to
fix this compile error on centos 6:
> In file included from
> Godeps/_workspace/src/github.com/opencontainers/runc/libcontainer/nsenter/nsexec.c:20:
> /usr/include/linux/netlink.h:35: error: expected specifier-qualifier-list before 'sa_family_t'
The glibc bits/sockaddr.h says that this header should never be included
directly[1]. Instead, sys/socket.h should be used.
The problem was correctly fixed later, in commit 394fb55 (Fix build
error on centos6, 2016-03-02) so the incorrect bits/sockaddr.h can
safely be removed.
This is needed to build musl libc.
Fixes#761
[1]: 20003c4988/bits/sockaddr.h (L20)
Signed-off-by: Natanael Copa <natanael.copa@docker.com>
Clears supplementary groups that have effect on the
mount permissions before joining the user specified
groups happens.
Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>
The rhel6 kernel returns EINVAL in this case
Known issue:
* CT with userns doesn't work
This is a copy of
d31e97fa28
to address https://github.com/opencontainers/runc/issues/613
Signed-off-by: Andrey Vagin <avagin@virtuozzo.com>
Signed-off-by: Andrew Fernandes <andrew@fernandes.org>
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)
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>
replace passing of pid and console path via environment variable with passing
them with netlink message via an established pipe.
this change requires us to set _LIBCONTAINER_INITTYPE and
_LIBCONTAINER_INITPIPE as the env environment of the bootstrap process as we
only send the bootstrap data for setns process right now. When init and setns
bootstrap process are unified (i.e., init use nsexec instead of Go to clone new
process), we can remove _LIBCONTAINER_INITTYPE.
Note:
- we read nlmsghdr first before reading the content so we can get the total
length of the payload and allocate buffer properly instead of allocating
one large buffer.
- check read bytes vs the wanted number. It's an error if we failed to read
the desired number of bytes from the pipe into the buffer.
Signed-off-by: Daniel, Dao Quang Minh <dqminh89@gmail.com>
When executing an additional process in a container, all namespaces are
entered but the user namespace. As a result, the process may be
executed as the host's root user. This has both functionality and
security implications.
Fix this by adding the missing user namespace to the array of
namespaces. Since joining a user namespace in which the caller is
already a member yields an error, skip namespaces we're already in.
Last, remove a needless and buggy AT_SYMLINK_NOFOLLOW in the code.
Signed-off-by: Ido Yariv <ido@wizery.com>
Mrunal Patel
Michael Crosby
Antonio Murdaca
Akihiro Suda
Aleksa Sarai
Giuseppe Scrivano
Alex Fang
yangshukui
Qiang Huang
Daniel, Dao Quang Minh
rajasec
Mrunal Patel
Natanael Copa
Tonis Tiigi
Andrey Vagin
Phil Estes
Ye Yin
Kenfe-Mickael Laventure
Andrew Fernandes
Bogdan Purcareata
Ido Yariv