get user and group information using securejoin and runc's user library

for the purposes of performance and security, we use securejoin to contstruct
the root fs's path so that symlinks are what they appear to be and no pointing
to something naughty.

then instead of chrooting to parse /etc/passwd|/etc/group, we now use the runc user/group
methods which saves us quite a bit of performance.

Signed-off-by: baude <bbaude@redhat.com>

3 files changed, 45 insertions, 63 deletions

diff --git a/libpod/container_api.go b/libpod/container_api.go
index 41a131ea2..83f93cf9e 100644
--- a/libpod/container_api.go
+++ b/libpod/container_api.go
@@ -10,8 +10,8 @@ import (
 	"time"
 
 	"github.com/containers/libpod/libpod/driver"
-	"github.com/containers/libpod/pkg/chrootuser"
 	"github.com/containers/libpod/pkg/inspect"
+	"github.com/containers/libpod/pkg/lookup"
 	"github.com/containers/storage/pkg/stringid"
 	"github.com/docker/docker/daemon/caps"
 	"github.com/pkg/errors"
@@ -292,13 +292,13 @@ func (c *Container) Exec(tty, privileged bool, env, cmd []string, user string) e
 	// the host
 	hostUser := ""
 	if user != "" {
-		uid, gid, err := chrootuser.GetUser(c.state.Mountpoint, user)
+		execUser, err := lookup.GetUserGroupInfo(c.state.Mountpoint, user, nil)
 		if err != nil {
-			return errors.Wrapf(err, "error getting user to launch exec session as")
+			return err
 		}
 
 		// runc expects user formatted as uid:gid
-		hostUser = fmt.Sprintf("%d:%d", uid, gid)
+		hostUser = fmt.Sprintf("%d:%d", execUser.Uid, execUser.Gid)
 	}
 
 	// Generate exec session ID
diff --git a/libpod/container_internal.go b/libpod/container_internal.go
index 2af216358..d928c4aed 100644
--- a/libpod/container_internal.go
+++ b/libpod/container_internal.go
@@ -5,6 +5,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"github.com/opencontainers/runc/libcontainer/user"
 	"io"
 	"io/ioutil"
 	"os"
@@ -14,9 +15,9 @@ import (
 	"syscall"
 
 	"github.com/containers/buildah/imagebuildah"
-	"github.com/containers/libpod/pkg/chrootuser"
 	"github.com/containers/libpod/pkg/hooks"
 	"github.com/containers/libpod/pkg/hooks/exec"
+	"github.com/containers/libpod/pkg/lookup"
 	"github.com/containers/libpod/pkg/resolvconf"
 	"github.com/containers/libpod/pkg/rootless"
 	"github.com/containers/libpod/pkg/secrets"
@@ -1029,7 +1030,8 @@ func (c *Container) writeStringToRundir(destFile, output string) (string, error)
 func (c *Container) generatePasswd() (string, error) {
 	var (
 		groupspec string
-		gid       uint32
+		group     *user.Group
+		gid       int
 	)
 	if c.config.User == "" {
 		return "", nil
@@ -1044,21 +1046,27 @@ func (c *Container) generatePasswd() (string, error) {
 	if err != nil {
 		return "", nil
 	}
-	// if UID exists inside of container rootfs /etc/passwd then
-	// don't generate passwd
-	if _, _, err := chrootuser.LookupUIDInContainer(c.state.Mountpoint, uid); err == nil {
+	// Lookup the user to see if it exists in the container image
+	_, err = lookup.GetUser(c.state.Mountpoint, userspec)
+	if err != nil && err != user.ErrNoPasswdEntries {
+		return "", err
+	}
+	if err == nil {
 		return "", nil
 	}
-	if err == nil && groupspec != "" {
+	if groupspec != "" {
 		if !c.state.Mounted {
 			return "", errors.Wrapf(ErrCtrStateInvalid, "container %s must be mounted in order to translate group field for passwd record", c.ID())
 		}
-		gid, err = chrootuser.GetGroup(c.state.Mountpoint, groupspec)
+		group, err = lookup.GetGroup(c.state.Mountpoint, groupspec)
 		if err != nil {
-			return "", errors.Wrapf(err, "unable to get gid from %s formporary passwd file")
+			if err == user.ErrNoGroupEntries {
+				return "", errors.Wrapf(err, "unable to get gid %s from group file", groupspec)
+			}
+			return "", err
 		}
+		gid = group.Gid
 	}
-
 	originPasswdFile := filepath.Join(c.state.Mountpoint, "/etc/passwd")
 	orig, err := ioutil.ReadFile(originPasswdFile)
 	if err != nil {
@@ -1153,6 +1161,7 @@ func (c *Container) generateHosts() (string, error) {
 }
 
 func (c *Container) addLocalVolumes(ctx context.Context, g *generate.Generator) error {
+	var uid, gid int
 	mountPoint := c.state.Mountpoint
 	if !c.state.Mounted {
 		return errors.Wrapf(ErrInternal, "container is not mounted")
@@ -1176,6 +1185,18 @@ func (c *Container) addLocalVolumes(ctx context.Context, g *generate.Generator)
 		}
 	}
 
+	if c.config.User != "" {
+		if !c.state.Mounted {
+			return errors.Wrapf(ErrCtrStateInvalid, "container %s must be mounted in order to translate User field", c.ID())
+		}
+		execUser, err := lookup.GetUserGroupInfo(c.state.Mountpoint, c.config.User, nil)
+		if err != nil {
+			return err
+		}
+		uid = execUser.Uid
+		gid = execUser.Gid
+	}
+
 	for k := range imageData.ContainerConfig.Volumes {
 		mount := spec.Mount{
 			Destination: k,
@@ -1186,19 +1207,6 @@ func (c *Container) addLocalVolumes(ctx context.Context, g *generate.Generator)
 			continue
 		}
 		volumePath := filepath.Join(c.config.StaticDir, "volumes", k)
-		var (
-			uid uint32
-			gid uint32
-		)
-		if c.config.User != "" {
-			if !c.state.Mounted {
-				return errors.Wrapf(ErrCtrStateInvalid, "container %s must be mounted in order to translate User field", c.ID())
-			}
-			uid, gid, err = chrootuser.GetUser(c.state.Mountpoint, c.config.User)
-			if err != nil {
-				return err
-			}
-		}
 
 		// Ensure the symlinks are resolved
 		resolvedSymlink, err := imagebuildah.ResolveSymLink(mountPoint, k)
@@ -1218,7 +1226,7 @@ func (c *Container) addLocalVolumes(ctx context.Context, g *generate.Generator)
 				return errors.Wrapf(err, "error creating directory %q for volume %q in container %q", volumePath, k, c.ID())
 			}
 
-			if err = os.Chown(srcPath, int(uid), int(gid)); err != nil {
+			if err = os.Chown(srcPath, uid, gid); err != nil {
 				return errors.Wrapf(err, "error chowning directory %q for volume %q in container %q", srcPath, k, c.ID())
 			}
 		}
@@ -1228,7 +1236,7 @@ func (c *Container) addLocalVolumes(ctx context.Context, g *generate.Generator)
 				return errors.Wrapf(err, "error creating directory %q for volume %q in container %q", volumePath, k, c.ID())
 			}
 
-			if err = os.Chown(volumePath, int(uid), int(gid)); err != nil {
+			if err = os.Chown(volumePath, uid, gid); err != nil {
 				return errors.Wrapf(err, "error chowning directory %q for volume %q in container %q", volumePath, k, c.ID())
 			}
 
diff --git a/libpod/container_internal_linux.go b/libpod/container_internal_linux.go
index 0a1784ba7..7bf2c71ca 100644
--- a/libpod/container_internal_linux.go
+++ b/libpod/container_internal_linux.go
@@ -19,12 +19,10 @@ import (
 	cnitypes "github.com/containernetworking/cni/pkg/types/current"
 	"github.com/containernetworking/plugins/pkg/ns"
 	crioAnnotations "github.com/containers/libpod/pkg/annotations"
-	"github.com/containers/libpod/pkg/chrootuser"
 	"github.com/containers/libpod/pkg/criu"
+	"github.com/containers/libpod/pkg/lookup"
 	"github.com/containers/libpod/pkg/rootless"
 	"github.com/containers/storage/pkg/idtools"
-	"github.com/cyphar/filepath-securejoin"
-	"github.com/opencontainers/runc/libcontainer/user"
 	spec "github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/opencontainers/runtime-tools/generate"
 	"github.com/opencontainers/selinux/go-selinux/label"
@@ -135,6 +133,10 @@ func (c *Container) cleanupNetwork() error {
 // Generate spec for a container
 // Accepts a map of the container's dependencies
 func (c *Container) generateSpec(ctx context.Context) (*spec.Spec, error) {
+	execUser, err := lookup.GetUserGroupInfo(c.state.Mountpoint, c.config.User, nil)
+	if err != nil {
+		return nil, err
+	}
 	g := generate.NewFromSpec(c.config.Spec)
 
 	// If network namespace was requested, add it now
@@ -188,7 +190,6 @@ func (c *Container) generateSpec(ctx context.Context) (*spec.Spec, error) {
 		}
 	}
 
-	var err error
 	if !rootless.IsRootless() {
 		if c.state.ExtensionStageHooks, err = c.setupOCIHooks(ctx, g.Config); err != nil {
 			return nil, errors.Wrapf(err, "error setting up OCI Hooks")
@@ -206,13 +207,9 @@ func (c *Container) generateSpec(ctx context.Context) (*spec.Spec, error) {
 		if !c.state.Mounted {
 			return nil, errors.Wrapf(ErrCtrStateInvalid, "container %s must be mounted in order to translate User field", c.ID())
 		}
-		uid, gid, err := chrootuser.GetUser(c.state.Mountpoint, c.config.User)
-		if err != nil {
-			return nil, err
-		}
 		// User and Group must go together
-		g.SetProcessUID(uid)
-		g.SetProcessGID(gid)
+		g.SetProcessUID(uint32(execUser.Uid))
+		g.SetProcessGID(uint32(execUser.Gid))
 	}
 
 	// Add addition groups if c.config.GroupAdd is not empty
@@ -220,11 +217,8 @@ func (c *Container) generateSpec(ctx context.Context) (*spec.Spec, error) {
 		if !c.state.Mounted {
 			return nil, errors.Wrapf(ErrCtrStateInvalid, "container %s must be mounted in order to add additional groups", c.ID())
 		}
-		for _, group := range c.config.Groups {
-			gid, err := chrootuser.GetGroup(c.state.Mountpoint, group)
-			if err != nil {
-				return nil, err
-			}
+		gids, _ := lookup.GetContainerGroups(c.config.Groups, c.state.Mountpoint, nil)
+		for _, gid := range gids {
 			g.AddProcessAdditionalGid(gid)
 		}
 	}
@@ -237,26 +231,6 @@ func (c *Container) generateSpec(ctx context.Context) (*spec.Spec, error) {
 
 	// Look up and add groups the user belongs to, if a group wasn't directly specified
 	if !rootless.IsRootless() && !strings.Contains(c.config.User, ":") {
-		var groupDest, passwdDest string
-		defaultExecUser := user.ExecUser{
-			Uid:  0,
-			Gid:  0,
-			Home: "/",
-		}
-
-		// Make sure the /etc/group  and /etc/passwd destinations are not a symlink to something naughty
-		if groupDest, err = securejoin.SecureJoin(c.state.Mountpoint, "/etc/group"); err != nil {
-			logrus.Debug(err)
-			return nil, err
-		}
-		if passwdDest, err = securejoin.SecureJoin(c.state.Mountpoint, "/etc/passwd"); err != nil {
-			logrus.Debug(err)
-			return nil, err
-		}
-		execUser, err := user.GetExecUserPath(c.config.User, &defaultExecUser, passwdDest, groupDest)
-		if err != nil {
-			return nil, err
-		}
 		for _, gid := range execUser.Sgids {
 			g.AddProcessAdditionalGid(uint32(gid))
 		}