Add secrets patch to podman

Adds support for mounting secrets especially on RHEL where the container
can use the host subsription to run yum

Signed-off-by: umohnani8 <umohnani@redhat.com>

Closes: #544
Approved by: rhatdan

pkg/secrets/secrets.go

@@ -0,0 +1,122 @@
+package secrets
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/containers/storage/pkg/chrootarchive"
+	rspec "github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/opencontainers/selinux/go-selinux/label"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+var (
+	// DefaultMountsFile holds the default mount paths in the form
+	// "host_path:container_path"
+	DefaultMountsFile = "/usr/share/containers/mounts.conf"
+	// OverrideMountsFile holds the default mount paths in the form
+	// "host_path:container_path" overridden by the user
+	OverrideMountsFile = "/etc/containers/mounts.conf"
+)
+
+func getMounts(filePath string) []string {
+	file, err := os.Open(filePath)
+	if err != nil {
+		logrus.Warnf("file %q not found, skipping...", filePath)
+		return nil
+	}
+	defer file.Close()
+	scanner := bufio.NewScanner(file)
+	if err = scanner.Err(); err != nil {
+		logrus.Warnf("error reading file %q, skipping...", filePath)
+		return nil
+	}
+	var mounts []string
+	for scanner.Scan() {
+		mounts = append(mounts, scanner.Text())
+	}
+	return mounts
+}
+
+// getHostAndCtrDir separates the host:container paths
+func getMountsMap(path string) (string, string, error) {
+	arr := strings.SplitN(path, ":", 2)
+	if len(arr) == 2 {
+		return arr[0], arr[1], nil
+	}
+	return "", "", errors.Errorf("unable to get host and container dir")
+}
+
+// SecretMounts copies the contents of host directory to container directory
+// and returns a list of mounts
+func SecretMounts(filePath, mountLabel, containerWorkingDir string) ([]rspec.Mount, error) {
+	var mounts []rspec.Mount
+	defaultMountsPaths := getMounts(filePath)
+	for _, path := range defaultMountsPaths {
+		hostDir, ctrDir, err := getMountsMap(path)
+		if err != nil {
+			return nil, err
+		}
+		// skip if the hostDir path doesn't exist
+		if _, err = os.Stat(hostDir); os.IsNotExist(err) {
+			logrus.Warnf("%q doesn't exist, skipping", hostDir)
+			continue
+		}
+
+		ctrDirOnHost := filepath.Join(containerWorkingDir, ctrDir)
+		if err = os.RemoveAll(ctrDirOnHost); err != nil {
+			return nil, fmt.Errorf("remove container directory failed: %v", err)
+		}
+
+		// In the event of a restart, don't want to copy secrets over again as they already would exist in ctrDirOnHost
+		_, err = os.Stat(ctrDirOnHost)
+		if os.IsNotExist(err) {
+			if err = os.MkdirAll(ctrDirOnHost, 0755); err != nil {
+				return nil, fmt.Errorf("making container directory failed: %v", err)
+			}
+
+			hostDir, err = resolveSymbolicLink(hostDir)
+			if err != nil {
+				return nil, err
+			}
+
+			if err = chrootarchive.NewArchiver(nil).CopyWithTar(hostDir, ctrDirOnHost); err != nil && !os.IsNotExist(err) {
+				return nil, errors.Wrapf(err, "error getting host secret data")
+			}
+
+			err = label.Relabel(ctrDirOnHost, mountLabel, false)
+			if err != nil {
+				return nil, errors.Wrap(err, "error applying correct labels")
+			}
+		} else if err != nil {
+			return nil, errors.Wrapf(err, "error getting status of %q", ctrDirOnHost)
+		}
+
+		m := rspec.Mount{
+			Source:      ctrDirOnHost,
+			Destination: ctrDir,
+			Type:        "bind",
+			Options:     []string{"bind"},
+		}
+
+		mounts = append(mounts, m)
+	}
+	return mounts, nil
+}
+
+// resolveSymbolicLink resolves a possbile symlink path. If the path is a symlink, returns resolved
+// path; if not, returns the original path.
+func resolveSymbolicLink(path string) (string, error) {
+	info, err := os.Lstat(path)
+	if err != nil {
+		return "", err
+	}
+	if info.Mode()&os.ModeSymlink != os.ModeSymlink {
+		return path, nil
+	}
+	return filepath.EvalSymlinks(path)
+}