Finish the refactor which was partially completed with commit
34536c498d, passing around IdentityMapping structs instead of pairs of
[]IDMap slices.
Existing code which uses []IDMap relies on zero-valued fields to be
valid, empty mappings. So in order to successfully finish the
refactoring without introducing bugs, their replacement therefore also
needs to have a useful zero value which represents an empty mapping.
Change IdentityMapping to be a pass-by-value type so that there are no
nil pointers to worry about.
The functionality provided by the deprecated NewIDMappingsFromMaps
function is required by unit tests to to construct arbitrary
IdentityMapping values. And the daemon will always need to access the
mappings to pass them to the Linux kernel. Accommodate these use cases
by exporting the struct fields instead. BuildKit currently depends on
the UIDs and GIDs methods so we cannot get rid of them yet.
Signed-off-by: Cory Snider <csnider@mirantis.com>
pkg/system historically has been a bit of a kitchen-sink of things that were
somewhat "system" related, but didn't have a good place for. EnsureRemoveAll()
is one of those utilities. EnsureRemoveAll() is used to both unmount and remove
a path, for which it depends on both github.com/moby/sys/mount, which in turn
depends on github.com/moby/sys/mountinfo.
pkg/system is imported in the CLI, but neither EnsureRemoveAll(), nor any of its
moby/sys dependencies are used on the client side, so let's move this function
somewhere else, to remove those dependencies from the CLI.
I looked for plausible locations that were related; it's used in:
- daemon
- daemon/graphdriver/XXX/
- plugin
I considered moving it into a (e.g.) "utils" package within graphdriver (but not
a huge fan of "utils" packages), and given that it felt (mostly) related to
cleaning up container filesystems, I decided to move it there.
Some things to follow-up on after this:
- Verify if this function is still needed (it feels a bit like a big hammer in
a "YOLO, let's try some things just in case it fails")
- Perhaps it should be integrated in `containerfs.Remove()` (so that it's used
automatically)
- Look if there's other implementations (and if they should be consolidated),
although (e.g.) the one in containerd is a copy of ours:
https://github.com/containerd/containerd/blob/v1.5.9/pkg/cri/server/helpers_linux.go#L200
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
daemon/graphdriver/fuse-overlayfs/fuseoverlayfs.go:101:63: SA9002: file mode '700' evaluates to 01274; did you mean '0700'? (staticcheck)
if err := idtools.MkdirAllAndChown(path.Join(home, linkDir), 700, currentID); err != nil {
^
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Do not use 0701 perms.
0701 dir perms allows anyone to traverse the docker dir.
It happens to allow any user to execute, as an example, suid binaries
from image rootfs dirs because it allows traversal AND critically
container users need to be able to do execute things.
0701 on lower directories also happens to allow any user to modify
things in, for instance, the overlay upper dir which neccessarily
has 0755 permissions.
This changes to use 0710 which allows users in the group to traverse.
In userns mode the UID owner is (real) root and the GID is the remapped
root's GID.
This prevents anyone but the remapped root to traverse our directories
(which is required for userns with runc).
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
(cherry picked from commit ef7237442147441a7cadcda0600be1186d81ac73)
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
(cherry picked from commit 93ac040bf0)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
The io/ioutil package has been deprecated in Go 1.16. This commit
replaces the existing io/ioutil functions with their new definitions in
io and os packages.
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>
Various dirs in /var/lib/docker contain data that needs to be mounted
into a container. For this reason, these dirs are set to be owned by the
remapped root user, otherwise there can be permissions issues.
However, this uneccessarily exposes these dirs to an unprivileged user
on the host.
Instead, set the ownership of these dirs to the real root (or rather the
UID/GID of dockerd) with 0701 permissions, which allows the remapped
root to enter the directories but not read/write to them.
The remapped root needs to enter these dirs so the container's rootfs
can be configured... e.g. to mount /etc/resolve.conf.
This prevents an unprivileged user from having read/write access to
these dirs on the host.
The flip side of this is now any user can enter these directories.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
(cherry picked from commit e908cc3901)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
The implementation in libcontainer/system is quite complicated,
and we only use it to detect if user-namespaces are enabled.
In addition, the implementation in containerd uses a sync.Once,
so that detection (and reading/parsing `/proc/self/uid_map`) is
only performed once.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Switch to moby/sys/mount and mountinfo. Keep the pkg/mount for potential
outside users.
This commit was generated by the following bash script:
```
set -e -u -o pipefail
for file in $(git grep -l 'docker/docker/pkg/mount"' | grep -v ^pkg/mount); do
sed -i -e 's#/docker/docker/pkg/mount"#/moby/sys/mount"#' \
-e 's#mount\.\(GetMounts\|Mounted\|Info\|[A-Za-z]*Filter\)#mountinfo.\1#g' \
$file
goimports -w $file
done
```
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
`fuse-overlayfs` provides rootless overlayfs functionality without depending
on any kernel patch.
Aside from rootless, `fuse-overlayfs` could be potentially used for eliminating
`chown()` calls that happen in userns-remap mode, because `fuse-overlayfs` also
provides shiftfs functionality.
System requirements:
* fuse-overlayfs needs to be installed. Tested with 0.7.6.
* kernel >= 4.18
Unit test: `go test -exec sudo -v ./daemon/graphdriver/fuse-overlayfs`
The implementation is based on Podman's `overlay` driver which supports
both kernel-mode overlayfs and fuse-overlayfs in the single driver instance:
https://github.com/containers/storage/blob/39a8d5ed/drivers/overlay/overlay.go
However, Moby's implementation aims to decouple `fuse-overlayfs` driver from the
kernel-mode driver (`overlay2`) for simplicity.
Fix#40218
Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
Cory Snider