666 lines
16 KiB
C
666 lines
16 KiB
C
/* process_keys.c: management of a process's keyrings
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*
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* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/keyctl.h>
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#include <linux/fs.h>
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#include <linux/err.h>
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#include <asm/uaccess.h>
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#include "internal.h"
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/* session keyring create vs join semaphore */
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static DECLARE_MUTEX(key_session_sem);
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/* the root user's tracking struct */
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struct key_user root_key_user = {
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.usage = ATOMIC_INIT(3),
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.consq = LIST_HEAD_INIT(root_key_user.consq),
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.lock = SPIN_LOCK_UNLOCKED,
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.nkeys = ATOMIC_INIT(2),
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.nikeys = ATOMIC_INIT(2),
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.uid = 0,
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};
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/* the root user's UID keyring */
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struct key root_user_keyring = {
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.usage = ATOMIC_INIT(1),
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.serial = 2,
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.type = &key_type_keyring,
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.user = &root_key_user,
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.lock = RW_LOCK_UNLOCKED,
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.sem = __RWSEM_INITIALIZER(root_user_keyring.sem),
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.perm = KEY_USR_ALL,
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.flags = KEY_FLAG_INSTANTIATED,
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.description = "_uid.0",
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#ifdef KEY_DEBUGGING
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.magic = KEY_DEBUG_MAGIC,
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#endif
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};
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/* the root user's default session keyring */
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struct key root_session_keyring = {
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.usage = ATOMIC_INIT(1),
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.serial = 1,
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.type = &key_type_keyring,
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.user = &root_key_user,
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.lock = RW_LOCK_UNLOCKED,
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.sem = __RWSEM_INITIALIZER(root_session_keyring.sem),
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.perm = KEY_USR_ALL,
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.flags = KEY_FLAG_INSTANTIATED,
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.description = "_uid_ses.0",
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#ifdef KEY_DEBUGGING
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.magic = KEY_DEBUG_MAGIC,
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#endif
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};
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/*****************************************************************************/
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/*
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* allocate the keyrings to be associated with a UID
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*/
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int alloc_uid_keyring(struct user_struct *user)
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{
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struct key *uid_keyring, *session_keyring;
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char buf[20];
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int ret;
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/* concoct a default session keyring */
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sprintf(buf, "_uid_ses.%u", user->uid);
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session_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, 0, NULL);
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if (IS_ERR(session_keyring)) {
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ret = PTR_ERR(session_keyring);
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goto error;
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}
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/* and a UID specific keyring, pointed to by the default session
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* keyring */
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sprintf(buf, "_uid.%u", user->uid);
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uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, 0,
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session_keyring);
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if (IS_ERR(uid_keyring)) {
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key_put(session_keyring);
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ret = PTR_ERR(uid_keyring);
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goto error;
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}
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/* install the keyrings */
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user->uid_keyring = uid_keyring;
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user->session_keyring = session_keyring;
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ret = 0;
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error:
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return ret;
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} /* end alloc_uid_keyring() */
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/*****************************************************************************/
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/*
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* deal with the UID changing
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*/
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void switch_uid_keyring(struct user_struct *new_user)
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{
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#if 0 /* do nothing for now */
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struct key *old;
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/* switch to the new user's session keyring if we were running under
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* root's default session keyring */
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if (new_user->uid != 0 &&
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current->session_keyring == &root_session_keyring
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) {
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atomic_inc(&new_user->session_keyring->usage);
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task_lock(current);
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old = current->session_keyring;
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current->session_keyring = new_user->session_keyring;
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task_unlock(current);
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key_put(old);
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}
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#endif
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} /* end switch_uid_keyring() */
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/*****************************************************************************/
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/*
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* install a fresh thread keyring, discarding the old one
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*/
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int install_thread_keyring(struct task_struct *tsk)
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{
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struct key *keyring, *old;
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char buf[20];
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int ret;
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sprintf(buf, "_tid.%u", tsk->pid);
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keyring = keyring_alloc(buf, tsk->uid, tsk->gid, 1, NULL);
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if (IS_ERR(keyring)) {
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ret = PTR_ERR(keyring);
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goto error;
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}
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task_lock(tsk);
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old = tsk->thread_keyring;
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tsk->thread_keyring = keyring;
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task_unlock(tsk);
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ret = 0;
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key_put(old);
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error:
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return ret;
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} /* end install_thread_keyring() */
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/*****************************************************************************/
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/*
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* make sure a process keyring is installed
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*/
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static int install_process_keyring(struct task_struct *tsk)
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{
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unsigned long flags;
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struct key *keyring;
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char buf[20];
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int ret;
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if (!tsk->signal->process_keyring) {
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sprintf(buf, "_pid.%u", tsk->tgid);
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keyring = keyring_alloc(buf, tsk->uid, tsk->gid, 1, NULL);
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if (IS_ERR(keyring)) {
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ret = PTR_ERR(keyring);
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goto error;
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}
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/* attach or swap keyrings */
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spin_lock_irqsave(&tsk->sighand->siglock, flags);
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if (!tsk->signal->process_keyring) {
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tsk->signal->process_keyring = keyring;
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keyring = NULL;
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}
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spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
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key_put(keyring);
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}
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ret = 0;
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error:
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return ret;
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} /* end install_process_keyring() */
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/*****************************************************************************/
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/*
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* install a session keyring, discarding the old one
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* - if a keyring is not supplied, an empty one is invented
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*/
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static int install_session_keyring(struct task_struct *tsk,
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struct key *keyring)
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{
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unsigned long flags;
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struct key *old;
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char buf[20];
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int ret;
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/* create an empty session keyring */
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if (!keyring) {
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sprintf(buf, "_ses.%u", tsk->tgid);
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keyring = keyring_alloc(buf, tsk->uid, tsk->gid, 1, NULL);
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if (IS_ERR(keyring)) {
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ret = PTR_ERR(keyring);
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goto error;
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}
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}
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else {
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atomic_inc(&keyring->usage);
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}
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/* install the keyring */
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spin_lock_irqsave(&tsk->sighand->siglock, flags);
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old = tsk->signal->session_keyring;
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tsk->signal->session_keyring = keyring;
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spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
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ret = 0;
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key_put(old);
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error:
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return ret;
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} /* end install_session_keyring() */
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/*****************************************************************************/
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/*
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* copy the keys in a thread group for fork without CLONE_THREAD
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*/
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int copy_thread_group_keys(struct task_struct *tsk)
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{
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unsigned long flags;
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key_check(current->thread_group->session_keyring);
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key_check(current->thread_group->process_keyring);
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/* no process keyring yet */
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tsk->signal->process_keyring = NULL;
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/* same session keyring */
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spin_lock_irqsave(¤t->sighand->siglock, flags);
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tsk->signal->session_keyring =
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key_get(current->signal->session_keyring);
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spin_unlock_irqrestore(¤t->sighand->siglock, flags);
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return 0;
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} /* end copy_thread_group_keys() */
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/*****************************************************************************/
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/*
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* copy the keys for fork
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*/
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int copy_keys(unsigned long clone_flags, struct task_struct *tsk)
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{
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key_check(tsk->thread_keyring);
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/* no thread keyring yet */
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tsk->thread_keyring = NULL;
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return 0;
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} /* end copy_keys() */
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/*****************************************************************************/
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/*
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* dispose of thread group keys upon thread group destruction
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*/
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void exit_thread_group_keys(struct signal_struct *tg)
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{
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key_put(tg->session_keyring);
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key_put(tg->process_keyring);
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} /* end exit_thread_group_keys() */
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/*****************************************************************************/
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/*
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* dispose of keys upon thread exit
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*/
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void exit_keys(struct task_struct *tsk)
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{
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key_put(tsk->thread_keyring);
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} /* end exit_keys() */
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/*****************************************************************************/
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/*
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* deal with execve()
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*/
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int exec_keys(struct task_struct *tsk)
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{
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unsigned long flags;
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struct key *old;
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/* newly exec'd tasks don't get a thread keyring */
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task_lock(tsk);
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old = tsk->thread_keyring;
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tsk->thread_keyring = NULL;
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task_unlock(tsk);
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key_put(old);
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/* discard the process keyring from a newly exec'd task */
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spin_lock_irqsave(&tsk->sighand->siglock, flags);
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old = tsk->signal->process_keyring;
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tsk->signal->process_keyring = NULL;
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spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
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key_put(old);
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return 0;
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} /* end exec_keys() */
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/*****************************************************************************/
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/*
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* deal with SUID programs
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* - we might want to make this invent a new session keyring
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*/
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int suid_keys(struct task_struct *tsk)
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{
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return 0;
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} /* end suid_keys() */
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/*****************************************************************************/
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/*
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* the filesystem user ID changed
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*/
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void key_fsuid_changed(struct task_struct *tsk)
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{
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/* update the ownership of the thread keyring */
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if (tsk->thread_keyring) {
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down_write(&tsk->thread_keyring->sem);
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write_lock(&tsk->thread_keyring->lock);
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tsk->thread_keyring->uid = tsk->fsuid;
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write_unlock(&tsk->thread_keyring->lock);
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up_write(&tsk->thread_keyring->sem);
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}
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} /* end key_fsuid_changed() */
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/*****************************************************************************/
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/*
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* the filesystem group ID changed
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*/
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void key_fsgid_changed(struct task_struct *tsk)
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{
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/* update the ownership of the thread keyring */
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if (tsk->thread_keyring) {
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down_write(&tsk->thread_keyring->sem);
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write_lock(&tsk->thread_keyring->lock);
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tsk->thread_keyring->gid = tsk->fsgid;
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write_unlock(&tsk->thread_keyring->lock);
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up_write(&tsk->thread_keyring->sem);
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}
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} /* end key_fsgid_changed() */
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/*****************************************************************************/
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/*
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* search the process keyrings for the first matching key
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* - we use the supplied match function to see if the description (or other
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* feature of interest) matches
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* - we return -EAGAIN if we didn't find any matching key
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* - we return -ENOKEY if we found only negative matching keys
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*/
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struct key *search_process_keyrings_aux(struct key_type *type,
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const void *description,
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key_match_func_t match)
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{
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struct task_struct *tsk = current;
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unsigned long flags;
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struct key *key, *ret, *err, *tmp;
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/* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
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* searchable, but we failed to find a key or we found a negative key;
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* otherwise we want to return a sample error (probably -EACCES) if
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* none of the keyrings were searchable
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*
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* in terms of priority: success > -ENOKEY > -EAGAIN > other error
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*/
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key = NULL;
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ret = NULL;
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err = ERR_PTR(-EAGAIN);
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/* search the thread keyring first */
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if (tsk->thread_keyring) {
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key = keyring_search_aux(tsk->thread_keyring, type,
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description, match);
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if (!IS_ERR(key))
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goto found;
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switch (PTR_ERR(key)) {
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case -EAGAIN: /* no key */
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if (ret)
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break;
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case -ENOKEY: /* negative key */
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ret = key;
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break;
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default:
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err = key;
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break;
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}
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}
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/* search the process keyring second */
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if (tsk->signal->process_keyring) {
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key = keyring_search_aux(tsk->signal->process_keyring,
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type, description, match);
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if (!IS_ERR(key))
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goto found;
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switch (PTR_ERR(key)) {
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case -EAGAIN: /* no key */
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if (ret)
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break;
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case -ENOKEY: /* negative key */
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ret = key;
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break;
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default:
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err = key;
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break;
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}
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}
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/* search the session keyring last */
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spin_lock_irqsave(&tsk->sighand->siglock, flags);
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tmp = tsk->signal->session_keyring;
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if (!tmp)
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tmp = tsk->user->session_keyring;
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atomic_inc(&tmp->usage);
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spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
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key = keyring_search_aux(tmp, type, description, match);
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key_put(tmp);
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if (!IS_ERR(key))
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goto found;
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switch (PTR_ERR(key)) {
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case -EAGAIN: /* no key */
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if (ret)
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break;
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case -ENOKEY: /* negative key */
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ret = key;
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break;
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default:
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err = key;
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break;
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}
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/* no key - decide on the error we're going to go for */
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key = ret ? ret : err;
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found:
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return key;
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} /* end search_process_keyrings_aux() */
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/*****************************************************************************/
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/*
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* search the process keyrings for the first matching key
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* - we return -EAGAIN if we didn't find any matching key
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* - we return -ENOKEY if we found only negative matching keys
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*/
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struct key *search_process_keyrings(struct key_type *type,
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const char *description)
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{
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return search_process_keyrings_aux(type, description, type->match);
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} /* end search_process_keyrings() */
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/*****************************************************************************/
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/*
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* lookup a key given a key ID from userspace with a given permissions mask
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* - don't create special keyrings unless so requested
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* - partially constructed keys aren't found unless requested
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*/
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struct key *lookup_user_key(key_serial_t id, int create, int partial,
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key_perm_t perm)
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{
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struct task_struct *tsk = current;
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unsigned long flags;
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struct key *key;
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int ret;
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key = ERR_PTR(-ENOKEY);
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switch (id) {
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case KEY_SPEC_THREAD_KEYRING:
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if (!tsk->thread_keyring) {
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if (!create)
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goto error;
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ret = install_thread_keyring(tsk);
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if (ret < 0) {
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key = ERR_PTR(ret);
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goto error;
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}
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}
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key = tsk->thread_keyring;
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atomic_inc(&key->usage);
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break;
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case KEY_SPEC_PROCESS_KEYRING:
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if (!tsk->signal->process_keyring) {
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if (!create)
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goto error;
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ret = install_process_keyring(tsk);
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if (ret < 0) {
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key = ERR_PTR(ret);
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goto error;
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}
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}
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key = tsk->signal->process_keyring;
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atomic_inc(&key->usage);
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break;
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case KEY_SPEC_SESSION_KEYRING:
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if (!tsk->signal->session_keyring) {
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/* always install a session keyring upon access if one
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* doesn't exist yet */
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ret = install_session_keyring(
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tsk, tsk->user->session_keyring);
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if (ret < 0)
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goto error;
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}
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spin_lock_irqsave(&tsk->sighand->siglock, flags);
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key = tsk->signal->session_keyring;
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atomic_inc(&key->usage);
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spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
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break;
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case KEY_SPEC_USER_KEYRING:
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key = tsk->user->uid_keyring;
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atomic_inc(&key->usage);
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break;
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case KEY_SPEC_USER_SESSION_KEYRING:
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key = tsk->user->session_keyring;
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atomic_inc(&key->usage);
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break;
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case KEY_SPEC_GROUP_KEYRING:
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/* group keyrings are not yet supported */
|
|
key = ERR_PTR(-EINVAL);
|
|
goto error;
|
|
|
|
default:
|
|
key = ERR_PTR(-EINVAL);
|
|
if (id < 1)
|
|
goto error;
|
|
|
|
key = key_lookup(id);
|
|
if (IS_ERR(key))
|
|
goto error;
|
|
break;
|
|
}
|
|
|
|
/* check the status and permissions */
|
|
if (perm) {
|
|
ret = key_validate(key);
|
|
if (ret < 0)
|
|
goto invalid_key;
|
|
}
|
|
|
|
ret = -EIO;
|
|
if (!partial && !(key->flags & KEY_FLAG_INSTANTIATED))
|
|
goto invalid_key;
|
|
|
|
ret = -EACCES;
|
|
if (!key_permission(key, perm))
|
|
goto invalid_key;
|
|
|
|
error:
|
|
return key;
|
|
|
|
invalid_key:
|
|
key_put(key);
|
|
key = ERR_PTR(ret);
|
|
goto error;
|
|
|
|
} /* end lookup_user_key() */
|
|
|
|
/*****************************************************************************/
|
|
/*
|
|
* join the named keyring as the session keyring if possible, or attempt to
|
|
* create a new one of that name if not
|
|
* - if the name is NULL, an empty anonymous keyring is installed instead
|
|
* - named session keyring joining is done with a semaphore held
|
|
*/
|
|
long join_session_keyring(const char *name)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
unsigned long flags;
|
|
struct key *keyring;
|
|
long ret;
|
|
|
|
/* if no name is provided, install an anonymous keyring */
|
|
if (!name) {
|
|
ret = install_session_keyring(tsk, NULL);
|
|
if (ret < 0)
|
|
goto error;
|
|
|
|
spin_lock_irqsave(&tsk->sighand->siglock, flags);
|
|
ret = tsk->signal->session_keyring->serial;
|
|
spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
|
|
goto error;
|
|
}
|
|
|
|
/* allow the user to join or create a named keyring */
|
|
down(&key_session_sem);
|
|
|
|
/* look for an existing keyring of this name */
|
|
keyring = find_keyring_by_name(name, 0);
|
|
if (PTR_ERR(keyring) == -ENOKEY) {
|
|
/* not found - try and create a new one */
|
|
keyring = keyring_alloc(name, tsk->uid, tsk->gid, 0, NULL);
|
|
if (IS_ERR(keyring)) {
|
|
ret = PTR_ERR(keyring);
|
|
goto error;
|
|
}
|
|
}
|
|
else if (IS_ERR(keyring)) {
|
|
ret = PTR_ERR(keyring);
|
|
goto error2;
|
|
}
|
|
|
|
/* we've got a keyring - now to install it */
|
|
ret = install_session_keyring(tsk, keyring);
|
|
if (ret < 0)
|
|
goto error2;
|
|
|
|
ret = keyring->serial;
|
|
key_put(keyring);
|
|
|
|
error2:
|
|
up(&key_session_sem);
|
|
error:
|
|
return ret;
|
|
|
|
} /* end join_session_keyring() */
|