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-rw-r--r--libpod/container_api.go29
-rw-r--r--libpod/container_internal_linux.go63
-rw-r--r--libpod/container_path_resolution.go166
3 files changed, 244 insertions, 14 deletions
diff --git a/libpod/container_api.go b/libpod/container_api.go
index 0d62a2dd7..951227a4f 100644
--- a/libpod/container_api.go
+++ b/libpod/container_api.go
@@ -776,3 +776,32 @@ func (c *Container) ShouldRestart(ctx context.Context) bool {
}
return c.shouldRestart()
}
+
+// ResolvePath resolves the specified path on the root for the container. The
+// root must either be the mounted image of the container or the already
+// mounted container storage.
+//
+// It returns the resolved root and the resolved path. Note that the path may
+// resolve to the container's mount point or to a volume or bind mount.
+func (c *Container) ResolvePath(ctx context.Context, root string, path string) (string, string, error) {
+ logrus.Debugf("Resolving path %q (root %q) on container %s", path, root, c.ID())
+
+ // Minimal sanity checks.
+ if len(root)*len(path) == 0 {
+ return "", "", errors.Wrapf(define.ErrInternal, "ResolvePath: root (%q) and path (%q) must be non empty", root, path)
+ }
+ if _, err := os.Stat(root); err != nil {
+ return "", "", errors.Wrapf(err, "cannot locate root to resolve path on container %s", c.ID())
+ }
+
+ if !c.batched {
+ c.lock.Lock()
+ defer c.lock.Unlock()
+
+ if err := c.syncContainer(); err != nil {
+ return "", "", err
+ }
+ }
+
+ return c.resolvePath(root, path)
+}
diff --git a/libpod/container_internal_linux.go b/libpod/container_internal_linux.go
index b41a3fa38..6c9489a08 100644
--- a/libpod/container_internal_linux.go
+++ b/libpod/container_internal_linux.go
@@ -174,25 +174,60 @@ func (c *Container) prepare() error {
return err
}
- // Ensure container entrypoint is created (if required)
- if c.config.CreateWorkingDir {
- workdir, err := securejoin.SecureJoin(c.state.Mountpoint, c.WorkingDir())
- if err != nil {
- return errors.Wrapf(err, "error creating path to container %s working dir", c.ID())
- }
- rootUID := c.RootUID()
- rootGID := c.RootGID()
+ // Make sure the workdir exists
+ if err := c.resolveWorkDir(); err != nil {
+ return err
+ }
- if err := os.MkdirAll(workdir, 0755); err != nil {
- if os.IsExist(err) {
- return nil
+ return nil
+}
+
+// resolveWorkDir resolves the container's workdir and, depending on the
+// configuration, will create it, or error out if it does not exist.
+// Note that the container must be mounted before.
+func (c *Container) resolveWorkDir() error {
+ workdir := c.WorkingDir()
+
+ // If the specified workdir is a subdir of a volume or mount,
+ // we don't need to do anything. The runtime is taking care of
+ // that.
+ if isPathOnVolume(c, workdir) || isPathOnBindMount(c, workdir) {
+ logrus.Debugf("Workdir %q resolved to a volume or mount", workdir)
+ return nil
+ }
+
+ _, resolvedWorkdir, err := c.resolvePath(c.state.Mountpoint, workdir)
+ if err != nil {
+ return err
+ }
+ logrus.Debugf("Workdir %q resolved to host path %q", workdir, resolvedWorkdir)
+
+ // No need to create it (e.g., `--workdir=/foo`), so let's make sure
+ // the path exists on the container.
+ if !c.config.CreateWorkingDir {
+ if _, err := os.Stat(resolvedWorkdir); err != nil {
+ if os.IsNotExist(err) {
+ return errors.Errorf("workdir %q does not exist on container %s", workdir, c.ID())
}
- return errors.Wrapf(err, "error creating container %s working dir", c.ID())
+ // This might be a serious error (e.g., permission), so
+ // we need to return the full error.
+ return errors.Wrapf(err, "error detecting workdir %q on container %s", workdir, c.ID())
}
+ }
+
+ // Ensure container entrypoint is created (if required).
+ rootUID := c.RootUID()
+ rootGID := c.RootGID()
- if err := os.Chown(workdir, rootUID, rootGID); err != nil {
- return errors.Wrapf(err, "error chowning container %s working directory to container root", c.ID())
+ if err := os.MkdirAll(resolvedWorkdir, 0755); err != nil {
+ if os.IsExist(err) {
+ return nil
}
+ return errors.Wrapf(err, "error creating container %s workdir", c.ID())
+ }
+
+ if err := os.Chown(resolvedWorkdir, rootUID, rootGID); err != nil {
+ return errors.Wrapf(err, "error chowning container %s workdir to container root", c.ID())
}
return nil
diff --git a/libpod/container_path_resolution.go b/libpod/container_path_resolution.go
new file mode 100644
index 000000000..805b3b947
--- /dev/null
+++ b/libpod/container_path_resolution.go
@@ -0,0 +1,166 @@
+package libpod
+
+import (
+ "path/filepath"
+ "strings"
+
+ securejoin "github.com/cyphar/filepath-securejoin"
+ "github.com/opencontainers/runtime-spec/specs-go"
+ "github.com/pkg/errors"
+ "github.com/sirupsen/logrus"
+)
+
+// resolveContainerPaths resolves the container's mount point and the container
+// path as specified by the user. Both may resolve to paths outside of the
+// container's mount point when the container path hits a volume or bind mount.
+//
+// It returns a bool, indicating whether containerPath resolves outside of
+// mountPoint (e.g., via a mount or volume), the resolved root (e.g., container
+// mount, bind mount or volume) and the resolved path on the root (absolute to
+// the host).
+func (container *Container) resolvePath(mountPoint string, containerPath string) (string, string, error) {
+ // Let's first make sure we have a path relative to the mount point.
+ pathRelativeToContainerMountPoint := containerPath
+ if !filepath.IsAbs(containerPath) {
+ // If the containerPath is not absolute, it's relative to the
+ // container's working dir. To be extra careful, let's first
+ // join the working dir with "/", and the add the containerPath
+ // to it.
+ pathRelativeToContainerMountPoint = filepath.Join(filepath.Join("/", container.WorkingDir()), containerPath)
+ }
+ resolvedPathOnTheContainerMountPoint := filepath.Join(mountPoint, pathRelativeToContainerMountPoint)
+ pathRelativeToContainerMountPoint = strings.TrimPrefix(pathRelativeToContainerMountPoint, mountPoint)
+ pathRelativeToContainerMountPoint = filepath.Join("/", pathRelativeToContainerMountPoint)
+
+ // Now we have an "absolute container Path" but not yet resolved on the
+ // host (e.g., "/foo/bar/file.txt"). As mentioned above, we need to
+ // check if "/foo/bar/file.txt" is on a volume or bind mount. To do
+ // that, we need to walk *down* the paths to the root. Assuming
+ // volume-1 is mounted to "/foo" and volume-2 is mounted to "/foo/bar",
+ // we must select "/foo/bar". Once selected, we need to rebase the
+ // remainder (i.e, "/file.txt") on the volume's mount point on the
+ // host. Same applies to bind mounts.
+
+ searchPath := pathRelativeToContainerMountPoint
+ for {
+ volume, err := findVolume(container, searchPath)
+ if err != nil {
+ return "", "", err
+ }
+ if volume != nil {
+ logrus.Debugf("Container path %q resolved to volume %q on path %q", containerPath, volume.Name(), searchPath)
+
+ // TODO: We really need to force the volume to mount
+ // before doing this, but that API is not exposed
+ // externally right now and doing so is beyond the scope
+ // of this commit.
+ mountPoint, err := volume.MountPoint()
+ if err != nil {
+ return "", "", err
+ }
+ if mountPoint == "" {
+ return "", "", errors.Errorf("volume %s is not mounted, cannot copy into it", volume.Name())
+ }
+
+ // We found a matching volume for searchPath. We now
+ // need to first find the relative path of our input
+ // path to the searchPath, and then join it with the
+ // volume's mount point.
+ pathRelativeToVolume := strings.TrimPrefix(pathRelativeToContainerMountPoint, searchPath)
+ absolutePathOnTheVolumeMount, err := securejoin.SecureJoin(mountPoint, pathRelativeToVolume)
+ if err != nil {
+ return "", "", err
+ }
+ return mountPoint, absolutePathOnTheVolumeMount, nil
+ }
+
+ if mount := findBindMount(container, searchPath); mount != nil {
+ logrus.Debugf("Container path %q resolved to bind mount %q:%q on path %q", containerPath, mount.Source, mount.Destination, searchPath)
+ // We found a matching bind mount for searchPath. We
+ // now need to first find the relative path of our
+ // input path to the searchPath, and then join it with
+ // the source of the bind mount.
+ pathRelativeToBindMount := strings.TrimPrefix(pathRelativeToContainerMountPoint, searchPath)
+ absolutePathOnTheBindMount, err := securejoin.SecureJoin(mount.Source, pathRelativeToBindMount)
+ if err != nil {
+ return "", "", err
+ }
+ return mount.Source, absolutePathOnTheBindMount, nil
+
+ }
+
+ if searchPath == "/" {
+ // Cannot go beyond "/", so we're done.
+ break
+ }
+
+ // Walk *down* the path (e.g., "/foo/bar/x" -> "/foo/bar").
+ searchPath = filepath.Dir(searchPath)
+ }
+
+ // No volume, no bind mount but just a normal path on the container.
+ return mountPoint, resolvedPathOnTheContainerMountPoint, nil
+}
+
+// findVolume checks if the specified containerPath matches the destination
+// path of a Volume. Returns a matching Volume or nil.
+func findVolume(c *Container, containerPath string) (*Volume, error) {
+ runtime := c.Runtime()
+ cleanedContainerPath := filepath.Clean(containerPath)
+ for _, vol := range c.Config().NamedVolumes {
+ if cleanedContainerPath == filepath.Clean(vol.Dest) {
+ return runtime.GetVolume(vol.Name)
+ }
+ }
+ return nil, nil
+}
+
+// isPathOnVolume returns true if the specified containerPath is a subdir of any
+// Volume's destination.
+func isPathOnVolume(c *Container, containerPath string) bool {
+ cleanedContainerPath := filepath.Clean(containerPath)
+ for _, vol := range c.Config().NamedVolumes {
+ if cleanedContainerPath == filepath.Clean(vol.Dest) {
+ return true
+ }
+ for dest := vol.Dest; dest != "/"; dest = filepath.Dir(dest) {
+ if cleanedContainerPath == dest {
+ return true
+ }
+ }
+ }
+ return false
+}
+
+// findBindMounts checks if the specified containerPath matches the destination
+// path of a Mount. Returns a matching Mount or nil.
+func findBindMount(c *Container, containerPath string) *specs.Mount {
+ cleanedPath := filepath.Clean(containerPath)
+ for _, m := range c.Config().Spec.Mounts {
+ if m.Type != "bind" {
+ continue
+ }
+ if cleanedPath == filepath.Clean(m.Destination) {
+ mount := m
+ return &mount
+ }
+ }
+ return nil
+}
+
+/// isPathOnBindMount returns true if the specified containerPath is a subdir of any
+// Mount's destination.
+func isPathOnBindMount(c *Container, containerPath string) bool {
+ cleanedContainerPath := filepath.Clean(containerPath)
+ for _, m := range c.Config().Spec.Mounts {
+ if cleanedContainerPath == filepath.Clean(m.Destination) {
+ return true
+ }
+ for dest := m.Destination; dest != "/"; dest = filepath.Dir(dest) {
+ if cleanedContainerPath == dest {
+ return true
+ }
+ }
+ }
+ return false
+}