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authorJoseph Richey <joerichey94@gmail.com>2017-10-24 13:19:08 -0700
committerJoseph Richey <joerichey94@gmail.com>2017-10-24 13:21:36 -0700
commitf7b99a39152694f72104b95e6a30e245248c75d7 (patch)
treed020baa01807d8e0e73ac7cbb2bc5edbc0c7b55e /security/keyring.go
parent6de6b14a09b3695fe797e5fd59a04b3c3834641a (diff)
crypto: Merge with security packagerefactor
Diffstat (limited to 'security/keyring.go')
-rw-r--r--security/keyring.go205
1 files changed, 0 insertions, 205 deletions
diff --git a/security/keyring.go b/security/keyring.go
deleted file mode 100644
index 7ce163e..0000000
--- a/security/keyring.go
+++ /dev/null
@@ -1,205 +0,0 @@
-/*
- * privileges.go - Handles inserting/removing into user keyrings.
- *
- * Copyright 2017 Google Inc.
- * Author: Joe Richey (joerichey@google.com)
- *
- * Licensed under the Apache License, Version 2.0 (the "License"); you may not
- * use this file except in compliance with the License. You may obtain a copy of
- * the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- * License for the specific language governing permissions and limitations under
- * the License.
- */
-
-package security
-
-import (
- "fmt"
- "log"
- "os"
- "os/user"
- "sync"
-
- "github.com/pkg/errors"
- "golang.org/x/sys/unix"
-
- "github.com/google/fscrypt/util"
-)
-
-// KeyType is always logon as required by filesystem encryption.
-const KeyType = "logon"
-
-// Keyring related error values
-var (
- ErrKeySearch = errors.New("could not find key with descriptor")
- ErrKeyRemove = util.SystemError("could not remove key from the keyring")
- ErrKeyInsert = util.SystemError("could not insert key into the keyring")
- ErrSessionUserKeying = errors.New("user keyring not linked into session keyring")
- ErrAccessUserKeyring = errors.New("could not access user keyring")
- ErrLinkUserKeyring = util.SystemError("could not link user keyring into root keyring")
-)
-
-// FindKey tries to locate a key in the kernel keyring with the provided
-// description. The key ID is returned if we can find the key. An error is
-// returned if the key does not exist.
-func FindKey(description string, target *user.User) (int, error) {
- keyringID, err := UserKeyringID(target, false)
- if err != nil {
- return 0, err
- }
-
- keyID, err := unix.KeyctlSearch(keyringID, KeyType, description, 0)
- log.Printf("KeyctlSearch(%d, %s, %s) = %d, %v", keyringID, KeyType, description, keyID, err)
- if err != nil {
- return 0, errors.Wrap(ErrKeySearch, err.Error())
- }
- return keyID, err
-}
-
-// RemoveKey tries to remove a policy key from the kernel keyring with the
-// provided description. An error is returned if the key does not exist.
-func RemoveKey(description string, target *user.User) error {
- keyID, err := FindKey(description, target)
- if err != nil {
- return err
- }
-
- // We use KEYCTL_INVALIDATE instead of KEYCTL_REVOKE because
- // invalidating a key immediately removes it.
- _, err = unix.KeyctlInt(unix.KEYCTL_INVALIDATE, keyID, 0, 0, 0)
- log.Printf("KeyctlInvalidate(%d) = %v", keyID, err)
- if err != nil {
- return errors.Wrap(ErrKeyRemove, err.Error())
- }
- return nil
-}
-
-// InsertKey puts the provided data into the kernel keyring with the provided
-// description.
-func InsertKey(data []byte, description string, target *user.User) error {
- keyringID, err := UserKeyringID(target, true)
- if err != nil {
- return err
- }
-
- keyID, err := unix.AddKey(KeyType, description, data, keyringID)
- log.Printf("KeyctlAddKey(%s, %s, <data>, %d) = %d, %v",
- KeyType, description, keyringID, keyID, err)
- if err != nil {
- return errors.Wrap(ErrKeyInsert, err.Error())
- }
- return nil
-}
-
-var (
- keyringIDCache = make(map[int]int)
- cacheLock sync.Mutex
-)
-
-// UserKeyringID returns the key id of the target user's user keyring. We also
-// ensure that the keyring will be accessible by linking it into the process
-// keyring and linking it into the root user keyring (permissions allowing). If
-// checkSession is true, an error is returned if a normal user requests their
-// user keyring, but it is not in the current session keyring.
-func UserKeyringID(target *user.User, checkSession bool) (int, error) {
- uid := util.AtoiOrPanic(target.Uid)
- targetKeyring, err := userKeyringIDLookup(uid)
- if err != nil {
- return 0, errors.Wrap(ErrAccessUserKeyring, err.Error())
- }
-
- if util.CurrentUserID() != 0 {
- // Make sure the returned keyring will be accessible by checking
- // that it is in the session keyring.
- if checkSession && !isUserKeyringInSession(uid) {
- return 0, ErrSessionUserKeying
- }
- return targetKeyring, nil
- }
-
- // Make sure the returned keyring will be accessible by linking it into
- // the root user's user keyring (which will not be garbage collected).
- rootKeyring, err := userKeyringIDLookup(0)
- if err != nil {
- return 0, errors.Wrap(ErrLinkUserKeyring, err.Error())
- }
-
- if rootKeyring != targetKeyring {
- if err = keyringLink(targetKeyring, rootKeyring); err != nil {
- return 0, errors.Wrap(ErrLinkUserKeyring, err.Error())
- }
- }
- return targetKeyring, nil
-}
-
-func userKeyringIDLookup(uid int) (int, error) {
- cacheLock.Lock()
- defer cacheLock.Unlock()
- if keyringID, ok := keyringIDCache[uid]; ok {
- return keyringID, nil
- }
-
- ruid, euid := os.Getuid(), os.Geteuid()
- // If all the ids do not agree, we will have to change them
- needSetUids := uid != ruid || uid != euid
-
- // The value of KEY_SPEC_USER_KEYRING is determined by the real uid, so
- // we must set the ruid appropriately. Note that this will also trigger
- // the creation of the uid keyring if it does not yet exist.
- if needSetUids {
- defer setUids(ruid, euid) // Always reset privileges
- if err := setUids(uid, 0); err != nil {
- return 0, err
- }
- }
- keyringID, err := unix.KeyctlGetKeyringID(unix.KEY_SPEC_USER_KEYRING, true)
- log.Printf("keyringID(_uid.%d) = %d, %v", uid, keyringID, err)
- if err != nil {
- return 0, err
- }
-
- // We still want to use this key after our privileges are reset. If we
- // link the key into the process keyring, we will possess it and still
- // be able to use it. However, the permissions to link are based on the
- // effective uid, so we must set the euid appropriately.
- if needSetUids {
- if err := setUids(0, uid); err != nil {
- return 0, err
- }
- }
- if err := keyringLink(keyringID, unix.KEY_SPEC_PROCESS_KEYRING); err != nil {
- return 0, err
- }
-
- keyringIDCache[uid] = keyringID
- return keyringID, nil
-}
-
-// isUserKeyringInSession tells us if the user's uid keyring is in the current
-// session keyring.
-func isUserKeyringInSession(uid int) bool {
- // We cannot use unix.KEY_SPEC_SESSION_KEYRING directly as that might
- // create a session keyring if one does not exist.
- sessionKeyring, err := unix.KeyctlGetKeyringID(unix.KEY_SPEC_SESSION_KEYRING, false)
- log.Printf("keyringID(session) = %d, %v", sessionKeyring, err)
- if err != nil {
- return false
- }
-
- description := fmt.Sprintf("_uid.%d", uid)
- id, err := unix.KeyctlSearch(sessionKeyring, "keyring", description, 0)
- log.Printf("KeyctlSearch(%d, keyring, %s) = %d, %v", sessionKeyring, description, id, err)
- return err == nil
-}
-
-func keyringLink(keyID int, keyringID int) error {
- _, err := unix.KeyctlInt(unix.KEYCTL_LINK, keyID, keyringID, 0, 0)
- log.Printf("KeyctlLink(%d, %d) = %v", keyID, keyringID, err)
- return err
-}