security_context.go

package provider

import (
	"fmt"
	"os/user"
	"strconv"

	corev1 "k8s.io/api/core/v1"
)

// uidGidFromSecurityContext returns the uid and gid (as a string) from the SecurityContext.
// If windowsOptions are set, the uid and gid *names* found there are returned. If these users
// can not be found on the system an error is returned. Every user must have a primary group, so
// either uid and gid or both empty or both set.
//
// If the uid is found, but gid is not, the primary group for uid is searched and returned.
// If no securityContext is found this returns the empty strings for uid and gid.
func uidGidFromSecurityContext(pod *corev1.Pod, maproot int) (uid, gid string, err error) {
	if pod.Spec.SecurityContext == nil {
		return "", "", nil
	}
	u := &user.User{}
	s := pod.Spec.SecurityContext
	if s.RunAsUser != nil {
		uid = strconv.FormatInt(*s.RunAsUser, 10)
		u, err = user.LookupId(uid)
		if err != nil {
			return "", "", err
		}
	}
	if s.RunAsGroup != nil {
		gid = strconv.FormatInt(*s.RunAsGroup, 10)
	}
	if s.WindowsOptions != nil {
		if s.WindowsOptions.RunAsUserName != nil {
			uid = *s.WindowsOptions.RunAsUserName
			u, err = user.Lookup(uid)
			if err != nil {
				return "", "", err
			}
			uid = u.Uid
		}
	}

	// if uid is set, but gid isn't, return the primary group for uid.
	if uid != "" && gid == "" {
		if u != nil {
			gid = u.Gid
		}
	}

	// Check if maproot is set and convert.
	if uid == "0" && maproot > 0 {
		mapuid := strconv.FormatInt(int64(maproot), 10)
		u, err = user.LookupId(mapuid)
		if err != nil {
			return "", "", fmt.Errorf("root override UID %q, not found: %s", mapuid, err)
		}
		uid = u.Uid
		gid = u.Gid
	}

	return uid, gid, nil
}