diff options
Diffstat (limited to 'security/privileges.go')
| -rw-r--r-- | security/privileges.go | 32 |
1 files changed, 22 insertions, 10 deletions
diff --git a/security/privileges.go b/security/privileges.go index cdabe71..f6e8098 100644 --- a/security/privileges.go +++ b/security/privileges.go @@ -39,6 +39,8 @@ var ( ErrKeyringInsert = util.SystemError("could not insert key into the keyring") ErrKeyringSearch = errors.New("could not find key with descriptor") ErrKeyringDelete = util.SystemError("could not delete key from the keyring") + ErrKeyringLink = util.SystemError("could not link keyring") + ErrKeyringUnlink = util.SystemError("could not unlink keyring") ) // Privileges contains the state needed to restore a user's original privileges. @@ -54,9 +56,8 @@ type Privileges struct { // Due to golang/go#1435, these privileges are only dropped for a single thread. // This function also makes sure that the appropriate user keyrings are linked. // This ensures that the user's keys are visible from commands like sudo. -func DropThreadPrivileges(euid int, egid int) (*Privileges, error) { - var err error - privs := &Privileges{ +func DropThreadPrivileges(euid int, egid int) (privs *Privileges, err error) { + privs = &Privileges{ euid: unix.Geteuid(), egid: unix.Getegid(), } @@ -68,32 +69,43 @@ func DropThreadPrivileges(euid int, egid int) (*Privileges, error) { // can still modify it after dropping privileges. privilegedUserKeyringID, err := getUserKeyringID() if err != nil { - return nil, err + return } if err = keyringLink(privilegedUserKeyringID, unix.KEY_SPEC_THREAD_KEYRING); err != nil { - return nil, err + return } defer keyringUnlink(privilegedUserKeyringID, unix.KEY_SPEC_THREAD_KEYRING) // Drop euid last so we have permissions to drop the others. if err = unix.Setregid(-1, egid); err != nil { - return nil, errors.Wrapf(err, "dropping egid to %d", egid) + err = errors.Wrapf(err, "dropping egid to %d", egid) + return } if err = unix.Setgroups([]int{egid}); err != nil { - return nil, errors.Wrapf(err, "dropping groups") + err = errors.Wrapf(err, "dropping groups") + return } if err = unix.Setreuid(-1, euid); err != nil { - return nil, errors.Wrapf(err, "dropping euid to %d", euid) + err = errors.Wrapf(err, "dropping euid to %d", euid) + return } log.Printf("privileges dropped to euid=%d, egid=%d", euid, egid) + // Failure should undo the privilege modification + defer func() { + if err != nil { + raiseErr := RaiseThreadPrivileges(privs) + log.Printf("when reverting privilege changes: %v", raiseErr) + } + }() + // If the link already exists, this linking does nothing and succeeds. droppedUserKeyringID, err := getUserKeyringID() if err != nil { - return nil, err + return } if err = keyringLink(droppedUserKeyringID, privilegedUserKeyringID); err != nil { - return nil, err + return } log.Printf("user keyring (%d) linked into root user keyring (%d)", droppedUserKeyringID, privilegedUserKeyringID) |