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Merge pull request #27599 from estesp/getent-path

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Add support for looking up user/groups via `getent`
This commit is contained in:
Justin Cormack 2016-11-03 15:11:42 +00:00 committed by GitHub
commit 81683e898a
4 changed files with 160 additions and 31 deletions
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13
daemon/daemon_unix.go
View file

@ -39,7 +39,6 @@ import (
"github.com/opencontainers/runc/libcontainer/cgroups"
"github.com/opencontainers/runc/libcontainer/label"
rsystem "github.com/opencontainers/runc/libcontainer/system"
"github.com/opencontainers/runc/libcontainer/user"
specs "github.com/opencontainers/runtime-spec/specs-go"
"github.com/pkg/errors"
"github.com/vishvananda/netlink"
@ -913,7 +912,7 @@ func parseRemappedRoot(usergrp string) (string, string, error) {
if uid, err := strconv.ParseInt(idparts[0], 10, 32); err == nil {
// must be a uid; take it as valid
userID = int(uid)
luser, err := user.LookupUid(userID)
luser, err := idtools.LookupUID(userID)
if err != nil {
return "", "", fmt.Errorf("Uid %d has no entry in /etc/passwd: %v", userID, err)
}
@ -921,7 +920,7 @@ func parseRemappedRoot(usergrp string) (string, string, error) {
if len(idparts) == 1 {
// if the uid was numeric and no gid was specified, take the uid as the gid
groupID = userID
lgrp, err := user.LookupGid(groupID)
lgrp, err := idtools.LookupGID(groupID)
if err != nil {
return "", "", fmt.Errorf("Gid %d has no entry in /etc/group: %v", groupID, err)
}
@ -934,7 +933,7 @@ func parseRemappedRoot(usergrp string) (string, string, error) {
if lookupName == defaultIDSpecifier {
lookupName = defaultRemappedID
}
luser, err := user.LookupUser(lookupName)
luser, err := idtools.LookupUser(lookupName)
if err != nil && idparts[0] != defaultIDSpecifier {
// error if the name requested isn't the special "dockremap" ID
return "", "", fmt.Errorf("Error during uid lookup for %q: %v", lookupName, err)
@ -951,7 +950,7 @@ func parseRemappedRoot(usergrp string) (string, string, error) {
username = luser.Name
if len(idparts) == 1 {
// we only have a string username, and no group specified; look up gid from username as group
group, err := user.LookupGroup(lookupName)
group, err := idtools.LookupGroup(lookupName)
if err != nil {
return "", "", fmt.Errorf("Error during gid lookup for %q: %v", lookupName, err)
}
@ -966,14 +965,14 @@ func parseRemappedRoot(usergrp string) (string, string, error) {
if gid, err := strconv.ParseInt(idparts[1], 10, 32); err == nil {
// must be a gid, take it as valid
groupID = int(gid)
lgrp, err := user.LookupGid(groupID)
lgrp, err := idtools.LookupGID(groupID)
if err != nil {
return "", "", fmt.Errorf("Gid %d has no entry in /etc/passwd: %v", groupID, err)
}
groupname = lgrp.Name
} else {
// not a number; attempt a lookup
if _, err := user.LookupGroup(idparts[1]); err != nil {
if _, err := idtools.LookupGroup(idparts[1]); err != nil {
return "", "", fmt.Errorf("Error during groupname lookup for %q: %v", idparts[1], err)
}
groupname = idparts[1]

122
pkg/idtools/idtools_unix.go
View file

@ -3,10 +3,22 @@
package idtools
import (
"bytes"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"sync"
"github.com/docker/docker/pkg/integration/cmd"
"github.com/docker/docker/pkg/system"
"github.com/opencontainers/runc/libcontainer/user"
)
var (
entOnce sync.Once
getentCmd string
)
func mkdirAs(path string, mode os.FileMode, ownerUID, ownerGID int, mkAll, chownExisting bool) error {
@ -84,3 +96,113 @@ func accessible(isOwner, isGroup bool, perms os.FileMode) bool {
}
return false
}
// LookupUser uses traditional local system files lookup (from libcontainer/user) on a username,
// followed by a call to `getent` for supporting host configured non-files passwd and group dbs
func LookupUser(username string) (user.User, error) {
// first try a local system files lookup using existing capabilities
usr, err := user.LookupUser(username)
if err == nil {
return usr, nil
}
// local files lookup failed; attempt to call `getent` to query configured passwd dbs
usr, err = getentUser(fmt.Sprintf("%s %s", "passwd", username))
if err != nil {
return user.User{}, err
}
return usr, nil
}
// LookupUID uses traditional local system files lookup (from libcontainer/user) on a uid,
// followed by a call to `getent` for supporting host configured non-files passwd and group dbs
func LookupUID(uid int) (user.User, error) {
// first try a local system files lookup using existing capabilities
usr, err := user.LookupUid(uid)
if err == nil {
return usr, nil
}
// local files lookup failed; attempt to call `getent` to query configured passwd dbs
return getentUser(fmt.Sprintf("%s %d", "passwd", uid))
}
func getentUser(args string) (user.User, error) {
reader, err := callGetent(args)
if err != nil {
return user.User{}, err
}
users, err := user.ParsePasswd(reader)
if err != nil {
return user.User{}, err
}
if len(users) == 0 {
return user.User{}, fmt.Errorf("getent failed to find passwd entry for %q", strings.Split(args, " ")[1])
}
return users[0], nil
}
// LookupGroup uses traditional local system files lookup (from libcontainer/user) on a group name,
// followed by a call to `getent` for supporting host configured non-files passwd and group dbs
func LookupGroup(groupname string) (user.Group, error) {
// first try a local system files lookup using existing capabilities
group, err := user.LookupGroup(groupname)
if err == nil {
return group, nil
}
// local files lookup failed; attempt to call `getent` to query configured group dbs
return getentGroup(fmt.Sprintf("%s %s", "group", groupname))
}
// LookupGID uses traditional local system files lookup (from libcontainer/user) on a group ID,
// followed by a call to `getent` for supporting host configured non-files passwd and group dbs
func LookupGID(gid int) (user.Group, error) {
// first try a local system files lookup using existing capabilities
group, err := user.LookupGid(gid)
if err == nil {
return group, nil
}
// local files lookup failed; attempt to call `getent` to query configured group dbs
return getentGroup(fmt.Sprintf("%s %d", "group", gid))
}
func getentGroup(args string) (user.Group, error) {
reader, err := callGetent(args)
if err != nil {
return user.Group{}, err
}
groups, err := user.ParseGroup(reader)
if err != nil {
return user.Group{}, err
}
if len(groups) == 0 {
return user.Group{}, fmt.Errorf("getent failed to find groups entry for %q", strings.Split(args, " ")[1])
}
return groups[0], nil
}
func callGetent(args string) (io.Reader, error) {
entOnce.Do(func() { getentCmd, _ = resolveBinary("getent") })
// if no `getent` command on host, can't do anything else
if getentCmd == "" {
return nil, fmt.Errorf("")
}
out, err := execCmd(getentCmd, args)
if err != nil {
exitCode, errC := cmd.GetExitCode(err)
if errC != nil {
return nil, err
}
switch exitCode {
case 1:
return nil, fmt.Errorf("getent reported invalid parameters/database unknown")
case 2:
terms := strings.Split(args, " ")
return nil, fmt.Errorf("getent unable to find entry %q in %s database", terms[1], terms[0])
case 3:
return nil, fmt.Errorf("getent database doesn't support enumeration")
default:
return nil, err
}
}
return bytes.NewReader(out), nil
}

24
pkg/idtools/usergroupadd_linux.go
View file

@ -2,8 +2,6 @@ package idtools
import (
"fmt"
"os/exec"
"path/filepath"
"regexp"
"sort"
"strconv"
@ -33,23 +31,6 @@ var (
userMod = "usermod"
)
func resolveBinary(binname string) (string, error) {
binaryPath, err := exec.LookPath(binname)
if err != nil {
return "", err
}
resolvedPath, err := filepath.EvalSymlinks(binaryPath)
if err != nil {
return "", err
}
//only return no error if the final resolved binary basename
//matches what was searched for
if filepath.Base(resolvedPath) == binname {
return resolvedPath, nil
}
return "", fmt.Errorf("Binary %q does not resolve to a binary of that name in $PATH (%q)", binname, resolvedPath)
}
// AddNamespaceRangesUser takes a username and uses the standard system
// utility to create a system user/group pair used to hold the
// /etc/sub{uid,gid} ranges which will be used for user namespace
@ -181,8 +162,3 @@ func wouldOverlap(arange subIDRange, ID int) bool {
}
return false
}
func execCmd(cmd, args string) ([]byte, error) {
execCmd := exec.Command(cmd, strings.Split(args, " ")...)
return execCmd.CombinedOutput()
}

32
pkg/idtools/utils_unix.go Normal file
View file

@ -0,0 +1,32 @@
// +build !windows
package idtools
import (
"fmt"
"os/exec"
"path/filepath"
"strings"
)
func resolveBinary(binname string) (string, error) {
binaryPath, err := exec.LookPath(binname)
if err != nil {
return "", err
}
resolvedPath, err := filepath.EvalSymlinks(binaryPath)
if err != nil {
return "", err
}
//only return no error if the final resolved binary basename
//matches what was searched for
if filepath.Base(resolvedPath) == binname {
return resolvedPath, nil
}
return "", fmt.Errorf("Binary %q does not resolve to a binary of that name in $PATH (%q)", binname, resolvedPath)
}
func execCmd(cmd, args string) ([]byte, error) {
execCmd := exec.Command(cmd, strings.Split(args, " ")...)
return execCmd.CombinedOutput()
}