podman image scp never enter podman user NS

Podman image scp should never enter the Podman UserNS unless it needs to. This allows for
a sudo exec.Command to transfer images to and from rootful storage. If this command is run using sudo,
the simple sudo podman save/load does not work, machinectl/su is necessary here.

This modification allows for both rootful and rootless transfers, and an overall change of scp to be
more of a wrapper function for different load and save calls as well as the ssh component

Signed-off-by: cdoern <cdoern@redhat.com>

1 files changed, 87 insertions, 0 deletions

diff --git a/cmd/podman/images/scp_utils.go b/cmd/podman/images/scp_utils.go
new file mode 100644
index 000000000..ebb874c1c
--- /dev/null
+++ b/cmd/podman/images/scp_utils.go
@@ -0,0 +1,87 @@
+package images
+
+import (
+	"strings"
+
+	"github.com/containers/image/v5/docker/reference"
+	"github.com/containers/podman/v3/libpod/define"
+	"github.com/containers/podman/v3/pkg/domain/entities"
+	"github.com/pkg/errors"
+)
+
+// parseImageSCPArg returns the valid connection, and source/destination data based off of the information provided by the user
+// arg is a string containing one of the cli arguments returned is a filled out source/destination options structs as well as a connections array and an error if applicable
+func parseImageSCPArg(arg string) (*entities.ImageScpOptions, []string, error) {
+	location := entities.ImageScpOptions{}
+	var err error
+	cliConnections := []string{}
+
+	switch {
+	case strings.Contains(arg, "@localhost"): // image transfer between users
+		location.User = strings.Split(arg, "@")[0]
+		location, err = validateImagePortion(location, arg)
+		if err != nil {
+			return nil, nil, err
+		}
+	case strings.Contains(arg, "::"):
+		location, err = validateImagePortion(location, arg)
+		if err != nil {
+			return nil, nil, err
+		}
+		location.Remote = true
+		cliConnections = append(cliConnections, arg)
+	default:
+		location.Image = arg
+	}
+	return &location, cliConnections, nil
+}
+
+// validateImagePortion is a helper function to validate the image name in an SCP argument
+func validateImagePortion(location entities.ImageScpOptions, arg string) (entities.ImageScpOptions, error) {
+	if remoteArgLength(arg, 1) > 0 {
+		err := validateImageName(strings.Split(arg, "::")[1])
+		if err != nil {
+			return location, err
+		}
+		location.Image = strings.Split(arg, "::")[1] // this will get checked/set again once we validate connections
+	}
+	return location, nil
+}
+
+// validateSCPArgs takes the array of source and destination options and checks for common errors
+func validateSCPArgs(locations []*entities.ImageScpOptions) (bool, error) {
+	if len(locations) > 2 {
+		return false, errors.Wrapf(define.ErrInvalidArg, "cannot specify more than two arguments")
+	}
+	switch {
+	case len(locations[0].Image) > 0 && len(locations[1].Image) > 0:
+		return false, errors.Wrapf(define.ErrInvalidArg, "cannot specify an image rename")
+	case len(locations[0].Image) == 0 && len(locations[1].Image) == 0:
+		return false, errors.Wrapf(define.ErrInvalidArg, "a source image must be specified")
+	case len(locations[0].Image) == 0 && len(locations[1].Image) != 0:
+		if locations[0].Remote && locations[1].Remote {
+			return true, nil // we need to flip the cliConnections array so the save/load connections are in the right place
+		}
+	}
+	return false, nil
+}
+
+// validateImageName makes sure that the image given is valid and no injections are occurring
+// we simply use this for error checking, bot setting the image
+func validateImageName(input string) error {
+	// ParseNormalizedNamed transforms a shortname image into its
+	// full name reference so busybox => docker.io/library/busybox
+	// we want to keep our shortnames, so only return an error if
+	// we cannot parse what the user has given us
+	_, err := reference.ParseNormalizedNamed(input)
+	return err
+}
+
+// remoteArgLength is a helper function to simplify the extracting of host argument data
+// returns an int which contains the length of a specified index in a host::image string
+func remoteArgLength(input string, side int) int {
+	if strings.Contains(input, "::") {
+		return len((strings.Split(input, "::"))[side])
+	}
+	return -1
+}