Namely, use an undocumented feature of pivot_root(2) where
pivot_root(".", ".") is actually a feature and allows you to make the
old_root be tied to your /proc/self/cwd in a way that makes unmounting
easy. Thanks a lot to the LXC developers which came up with this idea
first.
This is the first step of many to allowing runC to work with a
completely read-only rootfs.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
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>
We need support for read/only mounts in SELinux to allow a bunch of
containers to share the same read/only image. In order to do this
we need a new label which allows container processes to read/execute
all files but not write them.
Existing mount label is either shared write or private write. This
label is shared read/execute.
Signed-off-by: Dan Walsh <dwalsh@redhat.com>
At some point InitLabels was changed to look for SecuritOptions
separated by a ":" rather then an "=", but DupSecOpt was never
changed to match this default.
Signed-off-by: Dan Walsh <dwalsh@redhat.com>
If copyup is specified for a tmpfs mount, then the contents of the
underlying directory are copied into the tmpfs mounted over it.
Signed-off-by: Mrunal Patel <mrunalp@gmail.com>
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>
In order to mount root filesystems inside the container's mount
namespace as part of the spec we need to have the ability to do a bind
mount to / as the destination.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Since Linux 4.3 ambient capabilities are available. If set these allow unprivileged child
processes to inherit capabilities, while at present there is no means to set capabilities
on non root processes, other than via filesystem capabilities which are not usually
supported in image formats.
With ambient capabilities non root processes can be given capabilities as well, and so
the main reason to use root in containers goes away, and capabilities work as expected.
The code falls back to the existing behaviour if ambient capabilities are not supported.
Signed-off-by: Justin Cormack <justin.cormack@docker.com>
grep -r "range map" showw 3 parts use map to
range enum types, use slice instead can get
better performance and less memory usage.
Signed-off-by: Peng Gao <peng.gao.dut@gmail.com>
For example, the /sys/firmware directory should be masked because it can contain some sensitive files:
- /sys/firmware/acpi/tables/{SLIC,MSDM}: Windows license information:
- /sys/firmware/ibft/target0/chap-secret: iSCSI CHAP secret
Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>
Qiang Huang