![Linus Torvalds](/assets/img/avatar_default.png)
Pull user namespace enhancements from Eric Biederman: "This is a course correction for the user namespace, so that we can reach an inexpensive, maintainable, and reasonably complete implementation. Highlights: - Config guards make it impossible to enable the user namespace and code that has not been converted to be user namespace safe. - Use of the new kuid_t type ensures the if you somehow get past the config guards the kernel will encounter type errors if you enable user namespaces and attempt to compile in code whose permission checks have not been updated to be user namespace safe. - All uids from child user namespaces are mapped into the initial user namespace before they are processed. Removing the need to add an additional check to see if the user namespace of the compared uids remains the same. - With the user namespaces compiled out the performance is as good or better than it is today. - For most operations absolutely nothing changes performance or operationally with the user namespace enabled. - The worst case performance I could come up with was timing 1 billion cache cold stat operations with the user namespace code enabled. This went from 156s to 164s on my laptop (or 156ns to 164ns per stat operation). - (uid_t)-1 and (gid_t)-1 are reserved as an internal error value. Most uid/gid setting system calls treat these value specially anyway so attempting to use -1 as a uid would likely cause entertaining failures in userspace. - If setuid is called with a uid that can not be mapped setuid fails. I have looked at sendmail, login, ssh and every other program I could think of that would call setuid and they all check for and handle the case where setuid fails. - If stat or a similar system call is called from a context in which we can not map a uid we lie and return overflowuid. The LFS experience suggests not lying and returning an error code might be better, but the historical precedent with uids is different and I can not think of anything that would break by lying about a uid we can't map. - Capabilities are localized to the current user namespace making it safe to give the initial user in a user namespace all capabilities. My git tree covers all of the modifications needed to convert the core kernel and enough changes to make a system bootable to runlevel 1." Fix up trivial conflicts due to nearby independent changes in fs/stat.c * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (46 commits) userns: Silence silly gcc warning. cred: use correct cred accessor with regards to rcu read lock userns: Convert the move_pages, and migrate_pages permission checks to use uid_eq userns: Convert cgroup permission checks to use uid_eq userns: Convert tmpfs to use kuid and kgid where appropriate userns: Convert sysfs to use kgid/kuid where appropriate userns: Convert sysctl permission checks to use kuid and kgids. userns: Convert proc to use kuid/kgid where appropriate userns: Convert ext4 to user kuid/kgid where appropriate userns: Convert ext3 to use kuid/kgid where appropriate userns: Convert ext2 to use kuid/kgid where appropriate. userns: Convert devpts to use kuid/kgid where appropriate userns: Convert binary formats to use kuid/kgid where appropriate userns: Add negative depends on entries to avoid building code that is userns unsafe userns: signal remove unnecessary map_cred_ns userns: Teach inode_capable to understand inodes whose uids map to other namespaces. userns: Fail exec for suid and sgid binaries with ids outside our user namespace. userns: Convert stat to return values mapped from kuids and kgids userns: Convert user specfied uids and gids in chown into kuids and kgid userns: Use uid_eq gid_eq helpers when comparing kuids and kgids in the vfs ...
881 lines
21 KiB
C
881 lines
21 KiB
C
/* 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)
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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/keyctl.h>
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#include <linux/fs.h>
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#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 <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 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 = ATOMIC_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),
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.nikeys = ATOMIC_INIT(2),
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.uid = 0,
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.user_ns = &init_user_ns,
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};
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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;
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const struct cred *cred;
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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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cred = current_cred();
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user = cred->user;
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kenter("%p{%u}", user, user->uid);
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if (user->uid_keyring) {
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kleave(" = 0 [exist]");
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return 0;
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}
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mutex_lock(&key_user_keyring_mutex);
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ret = 0;
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if (!user->uid_keyring) {
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/* get the UID-specific keyring
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* - there may be one in existence already as it may have been
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* pinned by a session, but the user_struct pointing to it
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* may have been destroyed by setuid */
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sprintf(buf, "_uid.%u", user->uid);
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uid_keyring = find_keyring_by_name(buf, true);
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if (IS_ERR(uid_keyring)) {
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uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1,
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cred, KEY_ALLOC_IN_QUOTA,
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NULL);
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if (IS_ERR(uid_keyring)) {
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ret = PTR_ERR(uid_keyring);
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goto error;
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}
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}
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/* get a default session keyring (which might also exist
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* already) */
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sprintf(buf, "_uid_ses.%u", user->uid);
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session_keyring = find_keyring_by_name(buf, true);
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if (IS_ERR(session_keyring)) {
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session_keyring =
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keyring_alloc(buf, user->uid, (gid_t) -1,
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cred, KEY_ALLOC_IN_QUOTA, 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_release;
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}
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/* we install a link from the user session keyring to
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* the user keyring */
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ret = key_link(session_keyring, uid_keyring);
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if (ret < 0)
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goto error_release_both;
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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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}
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mutex_unlock(&key_user_keyring_mutex);
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kleave(" = 0");
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return 0;
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error_release_both:
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key_put(session_keyring);
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error_release:
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key_put(uid_keyring);
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error:
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mutex_unlock(&key_user_keyring_mutex);
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kleave(" = %d", ret);
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return ret;
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}
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/*
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* Install a fresh thread keyring directly to new credentials. This keyring is
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* allowed to overrun the quota.
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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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keyring = keyring_alloc("_tid", new->uid, new->gid, new,
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KEY_ALLOC_QUOTA_OVERRUN, NULL);
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if (IS_ERR(keyring))
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return PTR_ERR(keyring);
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new->thread_keyring = keyring;
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return 0;
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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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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();
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if (!new)
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return -ENOMEM;
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BUG_ON(new->thread_keyring);
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ret = install_thread_keyring_to_cred(new);
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if (ret < 0) {
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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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/*
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* Install a process keyring directly to a credentials struct.
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*
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* Returns -EEXIST if there was already a process keyring, 0 if one installed,
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* and other value on any other error
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*/
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int install_process_keyring_to_cred(struct cred *new)
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{
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struct key *keyring;
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int ret;
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if (new->tgcred->process_keyring)
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return -EEXIST;
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keyring = keyring_alloc("_pid", new->uid, new->gid,
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new, KEY_ALLOC_QUOTA_OVERRUN, NULL);
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if (IS_ERR(keyring))
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return PTR_ERR(keyring);
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spin_lock_irq(&new->tgcred->lock);
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if (!new->tgcred->process_keyring) {
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new->tgcred->process_keyring = keyring;
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keyring = NULL;
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ret = 0;
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} else {
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ret = -EEXIST;
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}
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spin_unlock_irq(&new->tgcred->lock);
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key_put(keyring);
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return ret;
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}
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/*
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* Make sure a process keyring is installed for the current process. The
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* existing process keyring is not replaced.
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*
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* Returns 0 if there is a process keyring by the end of this function, some
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* error otherwise.
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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();
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if (!new)
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return -ENOMEM;
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ret = install_process_keyring_to_cred(new);
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if (ret < 0) {
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abort_creds(new);
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return ret != -EEXIST ? ret : 0;
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}
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return commit_creds(new);
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}
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/*
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* Install a session keyring directly to a credentials struct.
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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 */
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if (!keyring) {
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flags = KEY_ALLOC_QUOTA_OVERRUN;
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if (cred->tgcred->session_keyring)
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flags = KEY_ALLOC_IN_QUOTA;
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keyring = keyring_alloc("_ses", cred->uid, cred->gid,
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cred, flags, NULL);
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if (IS_ERR(keyring))
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return PTR_ERR(keyring);
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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_irq(&cred->tgcred->lock);
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old = cred->tgcred->session_keyring;
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rcu_assign_pointer(cred->tgcred->session_keyring, keyring);
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spin_unlock_irq(&cred->tgcred->lock);
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/* we're using RCU on the pointer, but there's no point synchronising
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* on it if it didn't previously point to anything */
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if (old) {
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synchronize_rcu();
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key_put(old);
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}
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return 0;
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}
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/*
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* Install a session keyring, discarding the old one. If a keyring is not
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* supplied, an empty one is invented.
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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;
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int ret;
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new = prepare_creds();
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if (!new)
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return -ENOMEM;
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ret = install_session_keyring_to_cred(new, keyring);
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if (ret < 0) {
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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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/*
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* Handle the fsuid changing.
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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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BUG_ON(!tsk->cred);
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if (tsk->cred->thread_keyring) {
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down_write(&tsk->cred->thread_keyring->sem);
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tsk->cred->thread_keyring->uid = tsk->cred->fsuid;
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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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*/
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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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BUG_ON(!tsk->cred);
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if (tsk->cred->thread_keyring) {
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down_write(&tsk->cred->thread_keyring->sem);
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tsk->cred->thread_keyring->gid = tsk->cred->fsgid;
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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
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* matching key.
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*
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* The search criteria are the type and the match function. The description is
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* given to the match function as a parameter, but doesn't otherwise influence
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* the search. Typically the match function will compare the description
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* parameter to the key's description.
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*
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* This can only search keyrings that grant Search permission to the supplied
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* credentials. Keyrings linked to searched keyrings will also be searched if
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* they grant Search permission too. Keys can only be found if they grant
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* Search permission to the credentials.
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*
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* Returns a pointer to the key with the key usage count incremented if
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* successful, -EAGAIN if we didn't find any matching key or -ENOKEY if we only
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* matched negative keys.
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*
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* In the case of a successful return, the possession attribute is set on the
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* returned key reference.
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*/
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key_ref_t search_my_process_keyrings(struct key_type *type,
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const void *description,
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key_match_func_t match,
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bool no_state_check,
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const struct cred *cred)
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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
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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_ref = 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 (cred->thread_keyring) {
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key_ref = keyring_search_aux(
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make_key_ref(cred->thread_keyring, 1),
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cred, type, description, match, no_state_check);
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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 */
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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_ref;
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break;
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default:
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err = key_ref;
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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 (cred->tgcred->process_keyring) {
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key_ref = keyring_search_aux(
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make_key_ref(cred->tgcred->process_keyring, 1),
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cred, type, description, match, no_state_check);
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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 */
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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_ref;
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break;
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default:
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err = key_ref;
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break;
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}
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}
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/* search the session keyring */
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if (cred->tgcred->session_keyring) {
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rcu_read_lock();
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key_ref = keyring_search_aux(
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make_key_ref(rcu_dereference(
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cred->tgcred->session_keyring),
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1),
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cred, type, description, match, no_state_check);
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rcu_read_unlock();
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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 */
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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_ref;
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break;
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default:
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err = key_ref;
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break;
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}
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}
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/* or search the user-session keyring */
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else if (cred->user->session_keyring) {
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key_ref = keyring_search_aux(
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make_key_ref(cred->user->session_keyring, 1),
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cred, type, description, match, no_state_check);
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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 */
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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_ref;
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break;
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default:
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err = key_ref;
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break;
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}
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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_ref = ret ? ret : err;
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found:
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return key_ref;
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}
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/*
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* Search the process keyrings attached to the supplied cred for the first
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* matching key in the manner of search_my_process_keyrings(), but also search
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* the keys attached to the assumed authorisation key using its credentials if
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* one is available.
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*
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* Return same as search_my_process_keyrings().
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*/
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key_ref_t search_process_keyrings(struct key_type *type,
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const void *description,
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key_match_func_t match,
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const struct cred *cred)
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{
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struct request_key_auth *rka;
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key_ref_t key_ref, ret = ERR_PTR(-EACCES), err;
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might_sleep();
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key_ref = search_my_process_keyrings(type, description, match,
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false, cred);
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if (!IS_ERR(key_ref))
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goto found;
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err = key_ref;
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/* if this process has an instantiation authorisation key, then we also
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* search the keyrings of the process mentioned there
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* - we don't permit access to request_key auth keys via this method
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*/
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if (cred->request_key_auth &&
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cred == current_cred() &&
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type != &key_type_request_key_auth
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) {
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/* defend against the auth key being revoked */
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down_read(&cred->request_key_auth->sem);
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if (key_validate(cred->request_key_auth) == 0) {
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rka = cred->request_key_auth->payload.data;
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key_ref = search_process_keyrings(type, description,
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match, rka->cred);
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up_read(&cred->request_key_auth->sem);
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if (!IS_ERR(key_ref))
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goto found;
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ret = key_ref;
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|
} else {
|
|
up_read(&cred->request_key_auth->sem);
|
|
}
|
|
}
|
|
|
|
/* no key - decide on the error we're going to go for */
|
|
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;
|
|
|
|
found:
|
|
return key_ref;
|
|
}
|
|
|
|
/*
|
|
* See if the key we're looking at is the target key.
|
|
*/
|
|
int lookup_user_key_possessed(const struct key *key, const void *target)
|
|
{
|
|
return key == target;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
|
|
key_perm_t perm)
|
|
{
|
|
struct request_key_auth *rka;
|
|
const struct cred *cred;
|
|
struct key *key;
|
|
key_ref_t key_ref, skey_ref;
|
|
int ret;
|
|
|
|
try_again:
|
|
cred = get_current_cred();
|
|
key_ref = ERR_PTR(-ENOKEY);
|
|
|
|
switch (id) {
|
|
case KEY_SPEC_THREAD_KEYRING:
|
|
if (!cred->thread_keyring) {
|
|
if (!(lflags & KEY_LOOKUP_CREATE))
|
|
goto error;
|
|
|
|
ret = install_thread_keyring();
|
|
if (ret < 0) {
|
|
key_ref = ERR_PTR(ret);
|
|
goto error;
|
|
}
|
|
goto reget_creds;
|
|
}
|
|
|
|
key = cred->thread_keyring;
|
|
atomic_inc(&key->usage);
|
|
key_ref = make_key_ref(key, 1);
|
|
break;
|
|
|
|
case KEY_SPEC_PROCESS_KEYRING:
|
|
if (!cred->tgcred->process_keyring) {
|
|
if (!(lflags & KEY_LOOKUP_CREATE))
|
|
goto error;
|
|
|
|
ret = install_process_keyring();
|
|
if (ret < 0) {
|
|
key_ref = ERR_PTR(ret);
|
|
goto error;
|
|
}
|
|
goto reget_creds;
|
|
}
|
|
|
|
key = cred->tgcred->process_keyring;
|
|
atomic_inc(&key->usage);
|
|
key_ref = make_key_ref(key, 1);
|
|
break;
|
|
|
|
case KEY_SPEC_SESSION_KEYRING:
|
|
if (!cred->tgcred->session_keyring) {
|
|
/* always install a session keyring upon access if one
|
|
* doesn't exist yet */
|
|
ret = install_user_keyrings();
|
|
if (ret < 0)
|
|
goto error;
|
|
if (lflags & KEY_LOOKUP_CREATE)
|
|
ret = join_session_keyring(NULL);
|
|
else
|
|
ret = install_session_keyring(
|
|
cred->user->session_keyring);
|
|
|
|
if (ret < 0)
|
|
goto error;
|
|
goto reget_creds;
|
|
} else if (cred->tgcred->session_keyring ==
|
|
cred->user->session_keyring &&
|
|
lflags & KEY_LOOKUP_CREATE) {
|
|
ret = join_session_keyring(NULL);
|
|
if (ret < 0)
|
|
goto error;
|
|
goto reget_creds;
|
|
}
|
|
|
|
rcu_read_lock();
|
|
key = rcu_dereference(cred->tgcred->session_keyring);
|
|
atomic_inc(&key->usage);
|
|
rcu_read_unlock();
|
|
key_ref = make_key_ref(key, 1);
|
|
break;
|
|
|
|
case KEY_SPEC_USER_KEYRING:
|
|
if (!cred->user->uid_keyring) {
|
|
ret = install_user_keyrings();
|
|
if (ret < 0)
|
|
goto error;
|
|
}
|
|
|
|
key = cred->user->uid_keyring;
|
|
atomic_inc(&key->usage);
|
|
key_ref = make_key_ref(key, 1);
|
|
break;
|
|
|
|
case KEY_SPEC_USER_SESSION_KEYRING:
|
|
if (!cred->user->session_keyring) {
|
|
ret = install_user_keyrings();
|
|
if (ret < 0)
|
|
goto error;
|
|
}
|
|
|
|
key = cred->user->session_keyring;
|
|
atomic_inc(&key->usage);
|
|
key_ref = make_key_ref(key, 1);
|
|
break;
|
|
|
|
case KEY_SPEC_GROUP_KEYRING:
|
|
/* group keyrings are not yet supported */
|
|
key_ref = ERR_PTR(-EINVAL);
|
|
goto error;
|
|
|
|
case KEY_SPEC_REQKEY_AUTH_KEY:
|
|
key = cred->request_key_auth;
|
|
if (!key)
|
|
goto error;
|
|
|
|
atomic_inc(&key->usage);
|
|
key_ref = make_key_ref(key, 1);
|
|
break;
|
|
|
|
case KEY_SPEC_REQUESTOR_KEYRING:
|
|
if (!cred->request_key_auth)
|
|
goto error;
|
|
|
|
down_read(&cred->request_key_auth->sem);
|
|
if (test_bit(KEY_FLAG_REVOKED,
|
|
&cred->request_key_auth->flags)) {
|
|
key_ref = ERR_PTR(-EKEYREVOKED);
|
|
key = NULL;
|
|
} else {
|
|
rka = cred->request_key_auth->payload.data;
|
|
key = rka->dest_keyring;
|
|
atomic_inc(&key->usage);
|
|
}
|
|
up_read(&cred->request_key_auth->sem);
|
|
if (!key)
|
|
goto error;
|
|
key_ref = make_key_ref(key, 1);
|
|
break;
|
|
|
|
default:
|
|
key_ref = ERR_PTR(-EINVAL);
|
|
if (id < 1)
|
|
goto error;
|
|
|
|
key = key_lookup(id);
|
|
if (IS_ERR(key)) {
|
|
key_ref = ERR_CAST(key);
|
|
goto error;
|
|
}
|
|
|
|
key_ref = make_key_ref(key, 0);
|
|
|
|
/* check to see if we possess the key */
|
|
skey_ref = search_process_keyrings(key->type, key,
|
|
lookup_user_key_possessed,
|
|
cred);
|
|
|
|
if (!IS_ERR(skey_ref)) {
|
|
key_put(key);
|
|
key_ref = skey_ref;
|
|
}
|
|
|
|
break;
|
|
}
|
|
|
|
/* 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)) {
|
|
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) {
|
|
ret = key_validate(key);
|
|
if (ret < 0)
|
|
goto invalid_key;
|
|
}
|
|
|
|
ret = -EIO;
|
|
if (!(lflags & KEY_LOOKUP_PARTIAL) &&
|
|
!test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
|
|
goto invalid_key;
|
|
|
|
/* check the permissions */
|
|
ret = key_task_permission(key_ref, cred, perm);
|
|
if (ret < 0)
|
|
goto invalid_key;
|
|
|
|
key->last_used_at = current_kernel_time().tv_sec;
|
|
|
|
error:
|
|
put_cred(cred);
|
|
return key_ref;
|
|
|
|
invalid_key:
|
|
key_ref_put(key_ref);
|
|
key_ref = ERR_PTR(ret);
|
|
goto error;
|
|
|
|
/* if we attempted to install a keyring, then it may have caused new
|
|
* creds to be installed */
|
|
reget_creds:
|
|
put_cred(cred);
|
|
goto try_again;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
long join_session_keyring(const char *name)
|
|
{
|
|
const struct cred *old;
|
|
struct cred *new;
|
|
struct key *keyring;
|
|
long ret, serial;
|
|
|
|
/* only permit this if there's a single thread in the thread group -
|
|
* this avoids us having to adjust the creds on all threads and risking
|
|
* ENOMEM */
|
|
if (!current_is_single_threaded())
|
|
return -EMLINK;
|
|
|
|
new = prepare_creds();
|
|
if (!new)
|
|
return -ENOMEM;
|
|
old = current_cred();
|
|
|
|
/* if no name is provided, install an anonymous keyring */
|
|
if (!name) {
|
|
ret = install_session_keyring_to_cred(new, NULL);
|
|
if (ret < 0)
|
|
goto error;
|
|
|
|
serial = new->tgcred->session_keyring->serial;
|
|
ret = commit_creds(new);
|
|
if (ret == 0)
|
|
ret = serial;
|
|
goto okay;
|
|
}
|
|
|
|
/* allow the user to join or create a named keyring */
|
|
mutex_lock(&key_session_mutex);
|
|
|
|
/* look for an existing keyring of this name */
|
|
keyring = find_keyring_by_name(name, false);
|
|
if (PTR_ERR(keyring) == -ENOKEY) {
|
|
/* not found - try and create a new one */
|
|
keyring = keyring_alloc(name, old->uid, old->gid, old,
|
|
KEY_ALLOC_IN_QUOTA, NULL);
|
|
if (IS_ERR(keyring)) {
|
|
ret = PTR_ERR(keyring);
|
|
goto error2;
|
|
}
|
|
} else if (IS_ERR(keyring)) {
|
|
ret = PTR_ERR(keyring);
|
|
goto error2;
|
|
}
|
|
|
|
/* we've got a keyring - now to install it */
|
|
ret = install_session_keyring_to_cred(new, keyring);
|
|
if (ret < 0)
|
|
goto error2;
|
|
|
|
commit_creds(new);
|
|
mutex_unlock(&key_session_mutex);
|
|
|
|
ret = keyring->serial;
|
|
key_put(keyring);
|
|
okay:
|
|
return ret;
|
|
|
|
error2:
|
|
mutex_unlock(&key_session_mutex);
|
|
error:
|
|
abort_creds(new);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Replace a process's session keyring on behalf of one of its children when
|
|
* the target process is about to resume userspace execution.
|
|
*/
|
|
void key_replace_session_keyring(void)
|
|
{
|
|
const struct cred *old;
|
|
struct cred *new;
|
|
|
|
if (!current->replacement_session_keyring)
|
|
return;
|
|
|
|
write_lock_irq(&tasklist_lock);
|
|
new = current->replacement_session_keyring;
|
|
current->replacement_session_keyring = NULL;
|
|
write_unlock_irq(&tasklist_lock);
|
|
|
|
if (!new)
|
|
return;
|
|
|
|
old = current_cred();
|
|
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);
|
|
new->user_ns = get_user_ns(new->user_ns);
|
|
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;
|
|
new->cap_bset = old->cap_bset;
|
|
|
|
new->jit_keyring = old->jit_keyring;
|
|
new->thread_keyring = key_get(old->thread_keyring);
|
|
new->tgcred->tgid = old->tgcred->tgid;
|
|
new->tgcred->process_keyring = key_get(old->tgcred->process_keyring);
|
|
|
|
security_transfer_creds(new, old);
|
|
|
|
commit_creds(new);
|
|
}
|