package libpod import ( "fmt" "path/filepath" "strings" securejoin "github.com/cyphar/filepath-securejoin" "github.com/opencontainers/runtime-spec/specs-go" "github.com/sirupsen/logrus" ) // pathAbs returns an absolute path. If the specified path is // relative, it will be resolved relative to the container's working dir. func (c *Container) pathAbs(path string) string { if !filepath.IsAbs(path) { // 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. path = filepath.Join(filepath.Join("/", c.WorkingDir()), path) } return path } // 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 (c *Container) resolvePath(mountPoint string, containerPath string) (string, string, error) { // Let's first make sure we have a path relative to the mount point. pathRelativeToContainerMountPoint := c.pathAbs(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(c, 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 "", "", fmt.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(c, 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 } // isSubDir checks whether path is a subdirectory of root. func isSubDir(path, root string) bool { // check if the specified container path is below a bind mount. rel, err := filepath.Rel(root, path) if err != nil { return false } return rel != ".." && !strings.HasPrefix(rel, "../") } // 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 { cleanedDestination := filepath.Clean(vol.Dest) if cleanedContainerPath == cleanedDestination { return true } if isSubDir(cleanedContainerPath, cleanedDestination) { return true } for dest := cleanedDestination; 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 } /// isPathOnMount returns true if the specified containerPath is a subdir of any // Mount's destination. func isPathOnMount(c *Container, containerPath string) bool { cleanedContainerPath := filepath.Clean(containerPath) for _, m := range c.config.Spec.Mounts { cleanedDestination := filepath.Clean(m.Destination) if cleanedContainerPath == cleanedDestination { return true } if isSubDir(cleanedContainerPath, cleanedDestination) { return true } for dest := cleanedDestination; dest != "/" && dest != "."; dest = filepath.Dir(dest) { if cleanedContainerPath == dest { return true } } } return false }