117 строки
3.0 KiB
C
117 строки
3.0 KiB
C
/* Key permission checking
|
|
*
|
|
* Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
|
|
* 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/security.h>
|
|
#include "internal.h"
|
|
|
|
/**
|
|
* key_task_permission - Check a key can be used
|
|
* @key_ref: The key to check.
|
|
* @cred: The credentials to use.
|
|
* @perm: The permissions to check for.
|
|
*
|
|
* Check to see whether permission is granted to use a key in the desired way,
|
|
* but permit the security modules to override.
|
|
*
|
|
* The caller must hold either a ref on cred or must hold the RCU readlock.
|
|
*
|
|
* Returns 0 if successful, -EACCES if access is denied based on the
|
|
* permissions bits or the LSM check.
|
|
*/
|
|
int key_task_permission(const key_ref_t key_ref, const struct cred *cred,
|
|
key_perm_t perm)
|
|
{
|
|
struct key *key;
|
|
key_perm_t kperm;
|
|
int ret;
|
|
|
|
key = key_ref_to_ptr(key_ref);
|
|
|
|
if (key->user->user_ns != cred->user_ns)
|
|
goto use_other_perms;
|
|
|
|
/* use the second 8-bits of permissions for keys the caller owns */
|
|
if (key->uid == cred->fsuid) {
|
|
kperm = key->perm >> 16;
|
|
goto use_these_perms;
|
|
}
|
|
|
|
/* use the third 8-bits of permissions for keys the caller has a group
|
|
* membership in common with */
|
|
if (key->gid != -1 && key->perm & KEY_GRP_ALL) {
|
|
if (key->gid == cred->fsgid) {
|
|
kperm = key->perm >> 8;
|
|
goto use_these_perms;
|
|
}
|
|
|
|
ret = groups_search(cred->group_info,
|
|
make_kgid(current_user_ns(), key->gid));
|
|
if (ret) {
|
|
kperm = key->perm >> 8;
|
|
goto use_these_perms;
|
|
}
|
|
}
|
|
|
|
use_other_perms:
|
|
|
|
/* otherwise use the least-significant 8-bits */
|
|
kperm = key->perm;
|
|
|
|
use_these_perms:
|
|
|
|
/* use the top 8-bits of permissions for keys the caller possesses
|
|
* - possessor permissions are additive with other permissions
|
|
*/
|
|
if (is_key_possessed(key_ref))
|
|
kperm |= key->perm >> 24;
|
|
|
|
kperm = kperm & perm & KEY_ALL;
|
|
|
|
if (kperm != perm)
|
|
return -EACCES;
|
|
|
|
/* let LSM be the final arbiter */
|
|
return security_key_permission(key_ref, cred, perm);
|
|
}
|
|
EXPORT_SYMBOL(key_task_permission);
|
|
|
|
/**
|
|
* key_validate - Validate a key.
|
|
* @key: The key to be validated.
|
|
*
|
|
* Check that a key is valid, returning 0 if the key is okay, -ENOKEY if the
|
|
* key is invalidated, -EKEYREVOKED if the key's type has been removed or if
|
|
* the key has been revoked or -EKEYEXPIRED if the key has expired.
|
|
*/
|
|
int key_validate(const struct key *key)
|
|
{
|
|
unsigned long flags = key->flags;
|
|
|
|
if (flags & (1 << KEY_FLAG_INVALIDATED))
|
|
return -ENOKEY;
|
|
|
|
/* check it's still accessible */
|
|
if (flags & ((1 << KEY_FLAG_REVOKED) |
|
|
(1 << KEY_FLAG_DEAD)))
|
|
return -EKEYREVOKED;
|
|
|
|
/* check it hasn't expired */
|
|
if (key->expiry) {
|
|
struct timespec now = current_kernel_time();
|
|
if (now.tv_sec >= key->expiry)
|
|
return -EKEYEXPIRED;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(key_validate);
|