process_keys.c 21.2 KB
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/* Manage a process's keyrings
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 *
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 * Copyright (C) 2004-2005, 2008 Red Hat, Inc. All Rights Reserved.
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 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
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#include <linux/sched/user.h>
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#include <linux/keyctl.h>
#include <linux/fs.h>
#include <linux/err.h>
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#include <linux/mutex.h>
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#include <linux/security.h>
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#include <linux/user_namespace.h>
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#include <linux/uaccess.h>
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#include <keys/request_key_auth-type.h>
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#include "internal.h"

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/* Session keyring create vs join semaphore */
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static DEFINE_MUTEX(key_session_mutex);
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/* User keyring creation semaphore */
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static DEFINE_MUTEX(key_user_keyring_mutex);

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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		= REFCOUNT_INIT(3),
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	.cons_lock	= __MUTEX_INITIALIZER(root_key_user.cons_lock),
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	.lock		= __SPIN_LOCK_UNLOCKED(root_key_user.lock),
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	.nkeys		= ATOMIC_INIT(2),
	.nikeys		= ATOMIC_INIT(2),
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	.uid		= GLOBAL_ROOT_UID,
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};

/*
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 * Install the user and user session keyrings for the current process's UID.
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 */
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int install_user_keyrings(void)
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{
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	struct user_struct *user;
	const struct cred *cred;
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	struct key *uid_keyring, *session_keyring;
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	key_perm_t user_keyring_perm;
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	char buf[20];
	int ret;
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	uid_t uid;
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	user_keyring_perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL;
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	cred = current_cred();
	user = cred->user;
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	uid = from_kuid(cred->user_ns, user->uid);
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	kenter("%p{%u}", user, uid);
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	if (user->uid_keyring && user->session_keyring) {
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		kleave(" = 0 [exist]");
		return 0;
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	}

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	mutex_lock(&key_user_keyring_mutex);
	ret = 0;
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	if (!user->uid_keyring) {
		/* get the UID-specific keyring
		 * - there may be one in existence already as it may have been
		 *   pinned by a session, but the user_struct pointing to it
		 *   may have been destroyed by setuid */
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		sprintf(buf, "_uid.%u", uid);
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		uid_keyring = find_keyring_by_name(buf, true);
		if (IS_ERR(uid_keyring)) {
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			uid_keyring = keyring_alloc(buf, user->uid, INVALID_GID,
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						    cred, user_keyring_perm,
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						    KEY_ALLOC_UID_KEYRING |
							KEY_ALLOC_IN_QUOTA,
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						    NULL, NULL);
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			if (IS_ERR(uid_keyring)) {
				ret = PTR_ERR(uid_keyring);
				goto error;
			}
		}

		/* get a default session keyring (which might also exist
		 * already) */
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		sprintf(buf, "_uid_ses.%u", uid);
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		session_keyring = find_keyring_by_name(buf, true);
		if (IS_ERR(session_keyring)) {
			session_keyring =
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				keyring_alloc(buf, user->uid, INVALID_GID,
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					      cred, user_keyring_perm,
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					      KEY_ALLOC_UID_KEYRING |
						  KEY_ALLOC_IN_QUOTA,
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					      NULL, NULL);
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			if (IS_ERR(session_keyring)) {
				ret = PTR_ERR(session_keyring);
				goto error_release;
			}

			/* we install a link from the user session keyring to
			 * the user keyring */
			ret = key_link(session_keyring, uid_keyring);
			if (ret < 0)
				goto error_release_both;
		}

		/* install the keyrings */
		user->uid_keyring = uid_keyring;
		user->session_keyring = session_keyring;
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	}

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	mutex_unlock(&key_user_keyring_mutex);
	kleave(" = 0");
	return 0;
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error_release_both:
	key_put(session_keyring);
error_release:
	key_put(uid_keyring);
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error:
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	mutex_unlock(&key_user_keyring_mutex);
	kleave(" = %d", ret);
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	return ret;
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}
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/*
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 * Install a thread keyring to the given credentials struct if it didn't have
 * one already.  This is allowed to overrun the quota.
 *
 * Return: 0 if a thread keyring is now present; -errno on failure.
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 */
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int install_thread_keyring_to_cred(struct cred *new)
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{
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	struct key *keyring;
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	if (new->thread_keyring)
		return 0;

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	keyring = keyring_alloc("_tid", new->uid, new->gid, new,
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				KEY_POS_ALL | KEY_USR_VIEW,
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				KEY_ALLOC_QUOTA_OVERRUN,
				NULL, NULL);
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	if (IS_ERR(keyring))
		return PTR_ERR(keyring);
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	new->thread_keyring = keyring;
	return 0;
}
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/*
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 * Install a thread keyring to the current task if it didn't have one already.
 *
 * Return: 0 if a thread keyring is now present; -errno on failure.
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 */
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static int install_thread_keyring(void)
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{
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	struct cred *new;
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	int ret;

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	new = prepare_creds();
	if (!new)
		return -ENOMEM;
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	ret = install_thread_keyring_to_cred(new);
	if (ret < 0) {
		abort_creds(new);
		return ret;
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	}

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	return commit_creds(new);
}
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/*
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 * Install a process keyring to the given credentials struct if it didn't have
 * one already.  This is allowed to overrun the quota.
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 *
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 * Return: 0 if a process keyring is now present; -errno on failure.
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 */
int install_process_keyring_to_cred(struct cred *new)
{
	struct key *keyring;
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	if (new->process_keyring)
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		return 0;
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	keyring = keyring_alloc("_pid", new->uid, new->gid, new,
				KEY_POS_ALL | KEY_USR_VIEW,
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				KEY_ALLOC_QUOTA_OVERRUN,
				NULL, NULL);
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	if (IS_ERR(keyring))
		return PTR_ERR(keyring);

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	new->process_keyring = keyring;
	return 0;
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}
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/*
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 * Install a process keyring to the current task if it didn't have one already.
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 *
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 * Return: 0 if a process keyring is now present; -errno on failure.
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 */
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static int install_process_keyring(void)
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{
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	struct cred *new;
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	int ret;

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	new = prepare_creds();
	if (!new)
		return -ENOMEM;
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	ret = install_process_keyring_to_cred(new);
	if (ret < 0) {
		abort_creds(new);
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		return ret;
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	}

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	return commit_creds(new);
}
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/*
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 * Install the given keyring as the session keyring of the given credentials
 * struct, replacing the existing one if any.  If the given keyring is NULL,
 * then install a new anonymous session keyring.
 *
 * Return: 0 on success; -errno on failure.
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 */
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int install_session_keyring_to_cred(struct cred *cred, 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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	might_sleep();
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	/* create an empty session keyring */
	if (!keyring) {
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		flags = KEY_ALLOC_QUOTA_OVERRUN;
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		if (cred->session_keyring)
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			flags = KEY_ALLOC_IN_QUOTA;

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		keyring = keyring_alloc("_ses", cred->uid, cred->gid, cred,
					KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ,
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					flags, NULL, NULL);
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		if (IS_ERR(keyring))
			return PTR_ERR(keyring);
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	} else {
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		__key_get(keyring);
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	}

	/* install the keyring */
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	old = cred->session_keyring;
	rcu_assign_pointer(cred->session_keyring, keyring);

	if (old)
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		key_put(old);
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	return 0;
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}
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/*
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 * Install the given keyring as the session keyring of the current task,
 * replacing the existing one if any.  If the given keyring is NULL, then
 * install a new anonymous session keyring.
 *
 * Return: 0 on success; -errno on failure.
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 */
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static int install_session_keyring(struct key *keyring)
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{
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	struct cred *new;
	int ret;
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	new = prepare_creds();
	if (!new)
		return -ENOMEM;
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	ret = install_session_keyring_to_cred(new, keyring);
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	if (ret < 0) {
		abort_creds(new);
		return ret;
	}
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	return commit_creds(new);
}
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/*
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 * Handle the fsuid changing.
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 */
void key_fsuid_changed(struct task_struct *tsk)
{
	/* update the ownership of the thread keyring */
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	BUG_ON(!tsk->cred);
	if (tsk->cred->thread_keyring) {
		down_write(&tsk->cred->thread_keyring->sem);
		tsk->cred->thread_keyring->uid = tsk->cred->fsuid;
		up_write(&tsk->cred->thread_keyring->sem);
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	}
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}
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/*
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 * Handle the fsgid changing.
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 */
void key_fsgid_changed(struct task_struct *tsk)
{
	/* update the ownership of the thread keyring */
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	BUG_ON(!tsk->cred);
	if (tsk->cred->thread_keyring) {
		down_write(&tsk->cred->thread_keyring->sem);
		tsk->cred->thread_keyring->gid = tsk->cred->fsgid;
		up_write(&tsk->cred->thread_keyring->sem);
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	}
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}
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/*
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 * Search the process keyrings attached to the supplied cred for the first
 * matching key.
 *
 * The search criteria are the type and the match function.  The description is
 * given to the match function as a parameter, but doesn't otherwise influence
 * the search.  Typically the match function will compare the description
 * parameter to the key's description.
 *
 * This can only search keyrings that grant Search permission to the supplied
 * credentials.  Keyrings linked to searched keyrings will also be searched if
 * they grant Search permission too.  Keys can only be found if they grant
 * Search permission to the credentials.
 *
 * Returns a pointer to the key with the key usage count incremented if
 * successful, -EAGAIN if we didn't find any matching key or -ENOKEY if we only
 * matched negative keys.
 *
 * In the case of a successful return, the possession attribute is set on the
 * returned key reference.
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 */
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key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx)
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{
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	key_ref_t key_ref, ret, err;
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	/* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
	 * searchable, but we failed to find a key or we found a negative key;
	 * otherwise we want to return a sample error (probably -EACCES) if
	 * none of the keyrings were searchable
	 *
	 * in terms of priority: success > -ENOKEY > -EAGAIN > other error
	 */
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	key_ref = NULL;
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	ret = NULL;
	err = ERR_PTR(-EAGAIN);

	/* search the thread keyring first */
356
	if (ctx->cred->thread_keyring) {
357
		key_ref = keyring_search_aux(
358
			make_key_ref(ctx->cred->thread_keyring, 1), ctx);
359
		if (!IS_ERR(key_ref))
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			goto found;

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		switch (PTR_ERR(key_ref)) {
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		case -EAGAIN: /* no key */
		case -ENOKEY: /* negative key */
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			ret = key_ref;
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			break;
		default:
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			err = key_ref;
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			break;
		}
	}

	/* search the process keyring second */
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	if (ctx->cred->process_keyring) {
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		key_ref = keyring_search_aux(
376
			make_key_ref(ctx->cred->process_keyring, 1), ctx);
377
		if (!IS_ERR(key_ref))
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			goto found;

380
		switch (PTR_ERR(key_ref)) {
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		case -EAGAIN: /* no key */
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			if (ret)
				break;
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		case -ENOKEY: /* negative key */
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			ret = key_ref;
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			break;
		default:
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			err = key_ref;
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			break;
		}
	}

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	/* search the session keyring */
394
	if (ctx->cred->session_keyring) {
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		rcu_read_lock();
396
		key_ref = keyring_search_aux(
397 398
			make_key_ref(rcu_dereference(ctx->cred->session_keyring), 1),
			ctx);
399
		rcu_read_unlock();
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401
		if (!IS_ERR(key_ref))
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			goto found;

404
		switch (PTR_ERR(key_ref)) {
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		case -EAGAIN: /* no key */
			if (ret)
				break;
		case -ENOKEY: /* negative key */
409
			ret = key_ref;
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			break;
		default:
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			err = key_ref;
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			break;
		}
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	}
	/* or search the user-session keyring */
417
	else if (ctx->cred->user->session_keyring) {
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		key_ref = keyring_search_aux(
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			make_key_ref(ctx->cred->user->session_keyring, 1),
			ctx);
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		if (!IS_ERR(key_ref))
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			goto found;

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		switch (PTR_ERR(key_ref)) {
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		case -EAGAIN: /* no key */
			if (ret)
				break;
		case -ENOKEY: /* negative key */
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			ret = key_ref;
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			break;
		default:
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			err = key_ref;
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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 */
	key_ref = ret ? ret : err;

found:
	return key_ref;
}

/*
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 * Search the process keyrings attached to the supplied cred for the first
 * matching key in the manner of search_my_process_keyrings(), but also search
 * the keys attached to the assumed authorisation key using its credentials if
 * one is available.
 *
 * Return same as search_my_process_keyrings().
451
 */
452
key_ref_t search_process_keyrings(struct keyring_search_context *ctx)
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{
	struct request_key_auth *rka;
	key_ref_t key_ref, ret = ERR_PTR(-EACCES), err;

	might_sleep();

459
	key_ref = search_my_process_keyrings(ctx);
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	if (!IS_ERR(key_ref))
		goto found;
	err = key_ref;

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	/* if this process has an instantiation authorisation key, then we also
	 * search the keyrings of the process mentioned there
	 * - we don't permit access to request_key auth keys via this method
	 */
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	if (ctx->cred->request_key_auth &&
	    ctx->cred == current_cred() &&
	    ctx->index_key.type != &key_type_request_key_auth
471
	    ) {
472 473
		const struct cred *cred = ctx->cred;

474
		/* defend against the auth key being revoked */
475
		down_read(&cred->request_key_auth->sem);
476

477
		if (key_validate(ctx->cred->request_key_auth) == 0) {
478
			rka = ctx->cred->request_key_auth->payload.data[0];
479

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			ctx->cred = rka->cred;
			key_ref = search_process_keyrings(ctx);
			ctx->cred = cred;
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			up_read(&cred->request_key_auth->sem);
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			if (!IS_ERR(key_ref))
				goto found;

489
			ret = key_ref;
490
		} else {
491
			up_read(&cred->request_key_auth->sem);
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		}
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	}

	/* no key - decide on the error we're going to go for */
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	if (err == ERR_PTR(-ENOKEY) || ret == ERR_PTR(-ENOKEY))
		key_ref = ERR_PTR(-ENOKEY);
	else if (err == ERR_PTR(-EACCES))
		key_ref = ret;
	else
		key_ref = err;
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503
found:
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	return key_ref;
505
}
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507
/*
508
 * See if the key we're looking at is the target key.
509
 */
510 511
bool lookup_user_key_possessed(const struct key *key,
			       const struct key_match_data *match_data)
512
{
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	return key == match_data->raw_data;
514
}
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/*
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 * Look up a key ID given us by userspace with a given permissions mask to get
 * the key it refers to.
 *
 * Flags can be passed to request that special keyrings be created if referred
 * to directly, to permit partially constructed keys to be found and to skip
 * validity and permission checks on the found key.
 *
 * Returns a pointer to the key with an incremented usage count if successful;
 * -EINVAL if the key ID is invalid; -ENOKEY if the key ID does not correspond
 * to a key or the best found key was a negative key; -EKEYREVOKED or
 * -EKEYEXPIRED if the best found key was revoked or expired; -EACCES if the
 * found key doesn't grant the requested permit or the LSM denied access to it;
 * or -ENOMEM if a special keyring couldn't be created.
 *
 * In the case of a successful return, the possession attribute is set on the
 * returned key reference.
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 */
534
key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
535
			  key_perm_t perm)
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{
537
	struct keyring_search_context ctx = {
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		.match_data.cmp		= lookup_user_key_possessed,
		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
		.flags			= KEYRING_SEARCH_NO_STATE_CHECK,
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	};
542
	struct request_key_auth *rka;
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	struct key *key;
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	key_ref_t key_ref, skey_ref;
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	int ret;

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try_again:
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	ctx.cred = get_current_cred();
549
	key_ref = ERR_PTR(-ENOKEY);
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550 551 552

	switch (id) {
	case KEY_SPEC_THREAD_KEYRING:
553
		if (!ctx.cred->thread_keyring) {
554
			if (!(lflags & KEY_LOOKUP_CREATE))
L
Linus Torvalds 已提交
555 556
				goto error;

557
			ret = install_thread_keyring();
L
Linus Torvalds 已提交
558
			if (ret < 0) {
559
				key_ref = ERR_PTR(ret);
L
Linus Torvalds 已提交
560 561
				goto error;
			}
562
			goto reget_creds;
L
Linus Torvalds 已提交
563 564
		}

565
		key = ctx.cred->thread_keyring;
566
		__key_get(key);
567
		key_ref = make_key_ref(key, 1);
L
Linus Torvalds 已提交
568 569 570
		break;

	case KEY_SPEC_PROCESS_KEYRING:
571
		if (!ctx.cred->process_keyring) {
572
			if (!(lflags & KEY_LOOKUP_CREATE))
L
Linus Torvalds 已提交
573 574
				goto error;

575
			ret = install_process_keyring();
L
Linus Torvalds 已提交
576
			if (ret < 0) {
577
				key_ref = ERR_PTR(ret);
L
Linus Torvalds 已提交
578 579
				goto error;
			}
580
			goto reget_creds;
L
Linus Torvalds 已提交
581 582
		}

583
		key = ctx.cred->process_keyring;
584
		__key_get(key);
585
		key_ref = make_key_ref(key, 1);
L
Linus Torvalds 已提交
586 587 588
		break;

	case KEY_SPEC_SESSION_KEYRING:
589
		if (!ctx.cred->session_keyring) {
L
Linus Torvalds 已提交
590 591
			/* always install a session keyring upon access if one
			 * doesn't exist yet */
592
			ret = install_user_keyrings();
593 594
			if (ret < 0)
				goto error;
595 596 597 598
			if (lflags & KEY_LOOKUP_CREATE)
				ret = join_session_keyring(NULL);
			else
				ret = install_session_keyring(
599
					ctx.cred->user->session_keyring);
D
David Howells 已提交
600

L
Linus Torvalds 已提交
601 602
			if (ret < 0)
				goto error;
603
			goto reget_creds;
604 605
		} else if (ctx.cred->session_keyring ==
			   ctx.cred->user->session_keyring &&
606 607 608 609 610
			   lflags & KEY_LOOKUP_CREATE) {
			ret = join_session_keyring(NULL);
			if (ret < 0)
				goto error;
			goto reget_creds;
L
Linus Torvalds 已提交
611 612
		}

613
		rcu_read_lock();
614
		key = rcu_dereference(ctx.cred->session_keyring);
615
		__key_get(key);
616
		rcu_read_unlock();
617
		key_ref = make_key_ref(key, 1);
L
Linus Torvalds 已提交
618 619 620
		break;

	case KEY_SPEC_USER_KEYRING:
621
		if (!ctx.cred->user->uid_keyring) {
622
			ret = install_user_keyrings();
623 624 625 626
			if (ret < 0)
				goto error;
		}

627
		key = ctx.cred->user->uid_keyring;
628
		__key_get(key);
629
		key_ref = make_key_ref(key, 1);
L
Linus Torvalds 已提交
630 631 632
		break;

	case KEY_SPEC_USER_SESSION_KEYRING:
633
		if (!ctx.cred->user->session_keyring) {
634
			ret = install_user_keyrings();
635 636 637 638
			if (ret < 0)
				goto error;
		}

639
		key = ctx.cred->user->session_keyring;
640
		__key_get(key);
641
		key_ref = make_key_ref(key, 1);
L
Linus Torvalds 已提交
642 643 644 645
		break;

	case KEY_SPEC_GROUP_KEYRING:
		/* group keyrings are not yet supported */
646
		key_ref = ERR_PTR(-EINVAL);
L
Linus Torvalds 已提交
647 648
		goto error;

649
	case KEY_SPEC_REQKEY_AUTH_KEY:
650
		key = ctx.cred->request_key_auth;
651 652 653
		if (!key)
			goto error;

654
		__key_get(key);
655 656 657
		key_ref = make_key_ref(key, 1);
		break;

658
	case KEY_SPEC_REQUESTOR_KEYRING:
659
		if (!ctx.cred->request_key_auth)
660 661
			goto error;

662
		down_read(&ctx.cred->request_key_auth->sem);
663
		if (test_bit(KEY_FLAG_REVOKED,
664
			     &ctx.cred->request_key_auth->flags)) {
665 666 667
			key_ref = ERR_PTR(-EKEYREVOKED);
			key = NULL;
		} else {
668
			rka = ctx.cred->request_key_auth->payload.data[0];
669
			key = rka->dest_keyring;
670
			__key_get(key);
671
		}
672
		up_read(&ctx.cred->request_key_auth->sem);
673 674 675 676 677
		if (!key)
			goto error;
		key_ref = make_key_ref(key, 1);
		break;

L
Linus Torvalds 已提交
678
	default:
679
		key_ref = ERR_PTR(-EINVAL);
L
Linus Torvalds 已提交
680 681 682 683
		if (id < 1)
			goto error;

		key = key_lookup(id);
684
		if (IS_ERR(key)) {
685
			key_ref = ERR_CAST(key);
L
Linus Torvalds 已提交
686
			goto error;
687 688 689 690 691
		}

		key_ref = make_key_ref(key, 0);

		/* check to see if we possess the key */
692 693 694
		ctx.index_key.type		= key->type;
		ctx.index_key.description	= key->description;
		ctx.index_key.desc_len		= strlen(key->description);
D
David Howells 已提交
695
		ctx.match_data.raw_data		= key;
696 697 698
		kdebug("check possessed");
		skey_ref = search_process_keyrings(&ctx);
		kdebug("possessed=%p", skey_ref);
699 700 701 702 703 704

		if (!IS_ERR(skey_ref)) {
			key_put(key);
			key_ref = skey_ref;
		}

L
Linus Torvalds 已提交
705 706 707
		break;
	}

708 709 710 711 712 713 714 715
	/* unlink does not use the nominated key in any way, so can skip all
	 * the permission checks as it is only concerned with the keyring */
	if (lflags & KEY_LOOKUP_FOR_UNLINK) {
		ret = 0;
		goto error;
	}

	if (!(lflags & KEY_LOOKUP_PARTIAL)) {
716 717 718 719 720 721 722 723 724 725 726
		ret = wait_for_key_construction(key, true);
		switch (ret) {
		case -ERESTARTSYS:
			goto invalid_key;
		default:
			if (perm)
				goto invalid_key;
		case 0:
			break;
		}
	} else if (perm) {
L
Linus Torvalds 已提交
727 728 729 730 731 732
		ret = key_validate(key);
		if (ret < 0)
			goto invalid_key;
	}

	ret = -EIO;
733
	if (!(lflags & KEY_LOOKUP_PARTIAL) &&
734
	    key_read_state(key) == KEY_IS_UNINSTANTIATED)
L
Linus Torvalds 已提交
735 736
		goto invalid_key;

737
	/* check the permissions */
738
	ret = key_task_permission(key_ref, ctx.cred, perm);
739
	if (ret < 0)
L
Linus Torvalds 已提交
740 741
		goto invalid_key;

742
	key->last_used_at = ktime_get_real_seconds();
743

744
error:
745
	put_cred(ctx.cred);
746
	return key_ref;
L
Linus Torvalds 已提交
747

748 749 750
invalid_key:
	key_ref_put(key_ref);
	key_ref = ERR_PTR(ret);
L
Linus Torvalds 已提交
751 752
	goto error;

753 754 755
	/* if we attempted to install a keyring, then it may have caused new
	 * creds to be installed */
reget_creds:
756
	put_cred(ctx.cred);
757
	goto try_again;
758
}
759
EXPORT_SYMBOL(lookup_user_key);
760

L
Linus Torvalds 已提交
761
/*
762 763 764 765 766 767 768 769 770
 * Join the named keyring as the session keyring if possible else attempt to
 * create a new one of that name and join that.
 *
 * If the name is NULL, an empty anonymous keyring will be installed as the
 * session keyring.
 *
 * Named session keyrings are joined with a semaphore held to prevent the
 * keyrings from going away whilst the attempt is made to going them and also
 * to prevent a race in creating compatible session keyrings.
L
Linus Torvalds 已提交
771 772 773
 */
long join_session_keyring(const char *name)
{
D
David Howells 已提交
774 775
	const struct cred *old;
	struct cred *new;
L
Linus Torvalds 已提交
776
	struct key *keyring;
D
David Howells 已提交
777 778 779 780 781 782
	long ret, serial;

	new = prepare_creds();
	if (!new)
		return -ENOMEM;
	old = current_cred();
L
Linus Torvalds 已提交
783 784 785

	/* if no name is provided, install an anonymous keyring */
	if (!name) {
D
David Howells 已提交
786
		ret = install_session_keyring_to_cred(new, NULL);
L
Linus Torvalds 已提交
787 788 789
		if (ret < 0)
			goto error;

790
		serial = new->session_keyring->serial;
D
David Howells 已提交
791 792 793 794
		ret = commit_creds(new);
		if (ret == 0)
			ret = serial;
		goto okay;
L
Linus Torvalds 已提交
795 796 797
	}

	/* allow the user to join or create a named keyring */
I
Ingo Molnar 已提交
798
	mutex_lock(&key_session_mutex);
L
Linus Torvalds 已提交
799 800

	/* look for an existing keyring of this name */
801
	keyring = find_keyring_by_name(name, false);
L
Linus Torvalds 已提交
802 803
	if (PTR_ERR(keyring) == -ENOKEY) {
		/* not found - try and create a new one */
804 805 806
		keyring = keyring_alloc(
			name, old->uid, old->gid, old,
			KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_LINK,
807
			KEY_ALLOC_IN_QUOTA, NULL, NULL);
L
Linus Torvalds 已提交
808 809
		if (IS_ERR(keyring)) {
			ret = PTR_ERR(keyring);
810
			goto error2;
L
Linus Torvalds 已提交
811
		}
D
David Howells 已提交
812
	} else if (IS_ERR(keyring)) {
L
Linus Torvalds 已提交
813 814
		ret = PTR_ERR(keyring);
		goto error2;
815 816
	} else if (keyring == new->session_keyring) {
		ret = 0;
817
		goto error3;
L
Linus Torvalds 已提交
818 819 820
	}

	/* we've got a keyring - now to install it */
D
David Howells 已提交
821
	ret = install_session_keyring_to_cred(new, keyring);
L
Linus Torvalds 已提交
822
	if (ret < 0)
823
		goto error3;
L
Linus Torvalds 已提交
824

D
David Howells 已提交
825 826 827
	commit_creds(new);
	mutex_unlock(&key_session_mutex);

L
Linus Torvalds 已提交
828 829
	ret = keyring->serial;
	key_put(keyring);
D
David Howells 已提交
830 831
okay:
	return ret;
L
Linus Torvalds 已提交
832

833 834
error3:
	key_put(keyring);
835
error2:
I
Ingo Molnar 已提交
836
	mutex_unlock(&key_session_mutex);
837
error:
D
David Howells 已提交
838
	abort_creds(new);
L
Linus Torvalds 已提交
839
	return ret;
D
David Howells 已提交
840
}
841 842

/*
843 844
 * Replace a process's session keyring on behalf of one of its children when
 * the target  process is about to resume userspace execution.
845
 */
846
void key_change_session_keyring(struct callback_head *twork)
847
{
848
	const struct cred *old = current_cred();
849
	struct cred *new = container_of(twork, struct cred, rcu);
850

851 852
	if (unlikely(current->flags & PF_EXITING)) {
		put_cred(new);
853
		return;
854
	}
855 856 857 858 859 860 861 862 863 864

	new->  uid	= old->  uid;
	new-> euid	= old-> euid;
	new-> suid	= old-> suid;
	new->fsuid	= old->fsuid;
	new->  gid	= old->  gid;
	new-> egid	= old-> egid;
	new-> sgid	= old-> sgid;
	new->fsgid	= old->fsgid;
	new->user	= get_uid(old->user);
865
	new->user_ns	= get_user_ns(old->user_ns);
866 867 868 869 870 871
	new->group_info	= get_group_info(old->group_info);

	new->securebits	= old->securebits;
	new->cap_inheritable	= old->cap_inheritable;
	new->cap_permitted	= old->cap_permitted;
	new->cap_effective	= old->cap_effective;
872
	new->cap_ambient	= old->cap_ambient;
873 874 875 876
	new->cap_bset		= old->cap_bset;

	new->jit_keyring	= old->jit_keyring;
	new->thread_keyring	= key_get(old->thread_keyring);
877
	new->process_keyring	= key_get(old->process_keyring);
878 879 880 881 882

	security_transfer_creds(new, old);

	commit_creds(new);
}
883 884 885 886 887 888 889 890 891 892

/*
 * Make sure that root's user and user-session keyrings exist.
 */
static int __init init_root_keyring(void)
{
	return install_user_keyrings();
}

late_initcall(init_root_keyring);