linux-stable/security/keys/persistent.c
Linus Torvalds 028db3e290 Revert "Merge tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs"
This reverts merge 0f75ef6a9c (and thus
effectively commits

   7a1ade8475 ("keys: Provide KEYCTL_GRANT_PERMISSION")
   2e12256b9a ("keys: Replace uid/gid/perm permissions checking with an ACL")

that the merge brought in).

It turns out that it breaks booting with an encrypted volume, and Eric
biggers reports that it also breaks the fscrypt tests [1] and loading of
in-kernel X.509 certificates [2].

The root cause of all the breakage is likely the same, but David Howells
is off email so rather than try to work it out it's getting reverted in
order to not impact the rest of the merge window.

 [1] https://lore.kernel.org/lkml/20190710011559.GA7973@sol.localdomain/
 [2] https://lore.kernel.org/lkml/20190710013225.GB7973@sol.localdomain/

Link: https://lore.kernel.org/lkml/CAHk-=wjxoeMJfeBahnWH=9zShKp2bsVy527vo3_y8HfOdhwAAw@mail.gmail.com/
Reported-by: Eric Biggers <ebiggers@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-10 18:43:43 -07:00

167 lines
4.3 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* General persistent per-UID keyrings register
*
* Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/user_namespace.h>
#include <linux/cred.h>
#include "internal.h"
unsigned persistent_keyring_expiry = 3 * 24 * 3600; /* Expire after 3 days of non-use */
/*
* Create the persistent keyring register for the current user namespace.
*
* Called with the namespace's sem locked for writing.
*/
static int key_create_persistent_register(struct user_namespace *ns)
{
struct key *reg = keyring_alloc(".persistent_register",
KUIDT_INIT(0), KGIDT_INIT(0),
current_cred(),
((KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW | KEY_USR_READ),
KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL);
if (IS_ERR(reg))
return PTR_ERR(reg);
ns->persistent_keyring_register = reg;
return 0;
}
/*
* Create the persistent keyring for the specified user.
*
* Called with the namespace's sem locked for writing.
*/
static key_ref_t key_create_persistent(struct user_namespace *ns, kuid_t uid,
struct keyring_index_key *index_key)
{
struct key *persistent;
key_ref_t reg_ref, persistent_ref;
if (!ns->persistent_keyring_register) {
long err = key_create_persistent_register(ns);
if (err < 0)
return ERR_PTR(err);
} else {
reg_ref = make_key_ref(ns->persistent_keyring_register, true);
persistent_ref = find_key_to_update(reg_ref, index_key);
if (persistent_ref)
return persistent_ref;
}
persistent = keyring_alloc(index_key->description,
uid, INVALID_GID, current_cred(),
((KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW | KEY_USR_READ),
KEY_ALLOC_NOT_IN_QUOTA, NULL,
ns->persistent_keyring_register);
if (IS_ERR(persistent))
return ERR_CAST(persistent);
return make_key_ref(persistent, true);
}
/*
* Get the persistent keyring for a specific UID and link it to the nominated
* keyring.
*/
static long key_get_persistent(struct user_namespace *ns, kuid_t uid,
key_ref_t dest_ref)
{
struct keyring_index_key index_key;
struct key *persistent;
key_ref_t reg_ref, persistent_ref;
char buf[32];
long ret;
/* Look in the register if it exists */
memset(&index_key, 0, sizeof(index_key));
index_key.type = &key_type_keyring;
index_key.description = buf;
index_key.desc_len = sprintf(buf, "_persistent.%u", from_kuid(ns, uid));
key_set_index_key(&index_key);
if (ns->persistent_keyring_register) {
reg_ref = make_key_ref(ns->persistent_keyring_register, true);
down_read(&ns->keyring_sem);
persistent_ref = find_key_to_update(reg_ref, &index_key);
up_read(&ns->keyring_sem);
if (persistent_ref)
goto found;
}
/* It wasn't in the register, so we'll need to create it. We might
* also need to create the register.
*/
down_write(&ns->keyring_sem);
persistent_ref = key_create_persistent(ns, uid, &index_key);
up_write(&ns->keyring_sem);
if (!IS_ERR(persistent_ref))
goto found;
return PTR_ERR(persistent_ref);
found:
ret = key_task_permission(persistent_ref, current_cred(), KEY_NEED_LINK);
if (ret == 0) {
persistent = key_ref_to_ptr(persistent_ref);
ret = key_link(key_ref_to_ptr(dest_ref), persistent);
if (ret == 0) {
key_set_timeout(persistent, persistent_keyring_expiry);
ret = persistent->serial;
}
}
key_ref_put(persistent_ref);
return ret;
}
/*
* Get the persistent keyring for a specific UID and link it to the nominated
* keyring.
*/
long keyctl_get_persistent(uid_t _uid, key_serial_t destid)
{
struct user_namespace *ns = current_user_ns();
key_ref_t dest_ref;
kuid_t uid;
long ret;
/* -1 indicates the current user */
if (_uid == (uid_t)-1) {
uid = current_uid();
} else {
uid = make_kuid(ns, _uid);
if (!uid_valid(uid))
return -EINVAL;
/* You can only see your own persistent cache if you're not
* sufficiently privileged.
*/
if (!uid_eq(uid, current_uid()) &&
!uid_eq(uid, current_euid()) &&
!ns_capable(ns, CAP_SETUID))
return -EPERM;
}
/* There must be a destination keyring */
dest_ref = lookup_user_key(destid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
if (IS_ERR(dest_ref))
return PTR_ERR(dest_ref);
if (key_ref_to_ptr(dest_ref)->type != &key_type_keyring) {
ret = -ENOTDIR;
goto out_put_dest;
}
ret = key_get_persistent(ns, uid, dest_ref);
out_put_dest:
key_ref_put(dest_ref);
return ret;
}