[PATCH] Keys: Add LSM hooks for key management [try #3]
The attached patch adds LSM hooks for key management facilities. The notable
changes are:
(1) The key struct now supports a security pointer for the use of security
modules. This will permit key labelling and restrictions on which
programs may access a key.
(2) Security modules get a chance to note (or abort) the allocation of a key.
(3) The key permission checking can now be enhanced by the security modules;
the permissions check consults LSM if all other checks bear out.
(4) The key permissions checking functions now return an error code rather
than a boolean value.
(5) An extra permission has been added to govern the modification of
attributes (UID, GID, permissions).
Note that there isn't an LSM hook specifically for each keyctl() operation,
but rather the permissions hook allows control of individual operations based
on the permission request bits.
Key management access control through LSM is enabled by automatically if both
CONFIG_KEYS and CONFIG_SECURITY are enabled.
This should be applied on top of the patch ensubjected:
[PATCH] Keys: Possessor permissions should be additive
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/security/keys/key.c b/security/keys/key.c
index 2182be9..ccde17a 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -1,6 +1,6 @@
/* key.c: basic authentication token and access key management
*
- * Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved.
+ * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
@@ -13,6 +13,7 @@
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/slab.h>
+#include <linux/security.h>
#include <linux/workqueue.h>
#include <linux/err.h>
#include "internal.h"
@@ -253,6 +254,7 @@
struct key_user *user = NULL;
struct key *key;
size_t desclen, quotalen;
+ int ret;
key = ERR_PTR(-EINVAL);
if (!desc || !*desc)
@@ -305,6 +307,7 @@
key->flags = 0;
key->expiry = 0;
key->payload.data = NULL;
+ key->security = NULL;
if (!not_in_quota)
key->flags |= 1 << KEY_FLAG_IN_QUOTA;
@@ -315,16 +318,21 @@
key->magic = KEY_DEBUG_MAGIC;
#endif
+ /* let the security module know about the key */
+ ret = security_key_alloc(key);
+ if (ret < 0)
+ goto security_error;
+
/* publish the key by giving it a serial number */
atomic_inc(&user->nkeys);
key_alloc_serial(key);
- error:
+error:
return key;
- no_memory_3:
+security_error:
+ kfree(key->description);
kmem_cache_free(key_jar, key);
- no_memory_2:
if (!not_in_quota) {
spin_lock(&user->lock);
user->qnkeys--;
@@ -332,11 +340,24 @@
spin_unlock(&user->lock);
}
key_user_put(user);
- no_memory_1:
+ key = ERR_PTR(ret);
+ goto error;
+
+no_memory_3:
+ kmem_cache_free(key_jar, key);
+no_memory_2:
+ if (!not_in_quota) {
+ spin_lock(&user->lock);
+ user->qnkeys--;
+ user->qnbytes -= quotalen;
+ spin_unlock(&user->lock);
+ }
+ key_user_put(user);
+no_memory_1:
key = ERR_PTR(-ENOMEM);
goto error;
- no_quota:
+no_quota:
spin_unlock(&user->lock);
key_user_put(user);
key = ERR_PTR(-EDQUOT);
@@ -556,6 +577,8 @@
key_check(key);
+ security_key_free(key);
+
/* deal with the user's key tracking and quota */
if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
spin_lock(&key->user->lock);
@@ -700,8 +723,8 @@
int ret;
/* need write permission on the key to update it */
- ret = -EACCES;
- if (!key_permission(key_ref, KEY_WRITE))
+ ret = key_permission(key_ref, KEY_WRITE);
+ if (ret < 0)
goto error;
ret = -EEXIST;
@@ -711,7 +734,6 @@
down_write(&key->sem);
ret = key->type->update(key, payload, plen);
-
if (ret == 0)
/* updating a negative key instantiates it */
clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
@@ -768,9 +790,11 @@
/* if we're going to allocate a new key, we're going to have
* to modify the keyring */
- key_ref = ERR_PTR(-EACCES);
- if (!key_permission(keyring_ref, KEY_WRITE))
+ ret = key_permission(keyring_ref, KEY_WRITE);
+ if (ret < 0) {
+ key_ref = ERR_PTR(ret);
goto error_3;
+ }
/* search for an existing key of the same type and description in the
* destination keyring
@@ -780,8 +804,8 @@
goto found_matching_key;
/* decide on the permissions we want */
- perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK;
- perm |= KEY_USR_VIEW | KEY_USR_SEARCH | KEY_USR_LINK;
+ perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
+ perm |= KEY_USR_VIEW | KEY_USR_SEARCH | KEY_USR_LINK | KEY_USR_SETATTR;
if (ktype->read)
perm |= KEY_POS_READ | KEY_USR_READ;
@@ -840,16 +864,16 @@
key_check(key);
/* the key must be writable */
- ret = -EACCES;
- if (!key_permission(key_ref, KEY_WRITE))
+ ret = key_permission(key_ref, KEY_WRITE);
+ if (ret < 0)
goto error;
/* attempt to update it if supported */
ret = -EOPNOTSUPP;
if (key->type->update) {
down_write(&key->sem);
- ret = key->type->update(key, payload, plen);
+ ret = key->type->update(key, payload, plen);
if (ret == 0)
/* updating a negative key instantiates it */
clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 4c670ee..b7a468f 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -624,8 +624,8 @@
/* link the resulting key to the destination keyring if we can */
if (dest_ref) {
- ret = -EACCES;
- if (!key_permission(key_ref, KEY_LINK))
+ ret = key_permission(key_ref, KEY_LINK);
+ if (ret < 0)
goto error6;
ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
@@ -676,8 +676,11 @@
key = key_ref_to_ptr(key_ref);
/* see if we can read it directly */
- if (key_permission(key_ref, KEY_READ))
+ ret = key_permission(key_ref, KEY_READ);
+ if (ret == 0)
goto can_read_key;
+ if (ret != -EACCES)
+ goto error;
/* we can't; see if it's searchable from this process's keyrings
* - we automatically take account of the fact that it may be
@@ -726,7 +729,7 @@
if (uid == (uid_t) -1 && gid == (gid_t) -1)
goto error;
- key_ref = lookup_user_key(NULL, id, 1, 1, 0);
+ key_ref = lookup_user_key(NULL, id, 1, 1, KEY_SETATTR);
if (IS_ERR(key_ref)) {
ret = PTR_ERR(key_ref);
goto error;
@@ -786,7 +789,7 @@
if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
goto error;
- key_ref = lookup_user_key(NULL, id, 1, 1, 0);
+ key_ref = lookup_user_key(NULL, id, 1, 1, KEY_SETATTR);
if (IS_ERR(key_ref)) {
ret = PTR_ERR(key_ref);
goto error;
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index 0639396..e1cc4dd 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -13,6 +13,7 @@
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/slab.h>
+#include <linux/security.h>
#include <linux/seq_file.h>
#include <linux/err.h>
#include <asm/uaccess.h>
@@ -309,7 +310,9 @@
int ret;
keyring = key_alloc(&key_type_keyring, description,
- uid, gid, KEY_POS_ALL | KEY_USR_ALL, not_in_quota);
+ uid, gid,
+ (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
+ not_in_quota);
if (!IS_ERR(keyring)) {
ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
@@ -359,9 +362,11 @@
key_check(keyring);
/* top keyring must have search permission to begin the search */
- key_ref = ERR_PTR(-EACCES);
- if (!key_task_permission(keyring_ref, context, KEY_SEARCH))
+ err = key_task_permission(keyring_ref, context, KEY_SEARCH);
+ if (err < 0) {
+ key_ref = ERR_PTR(err);
goto error;
+ }
key_ref = ERR_PTR(-ENOTDIR);
if (keyring->type != &key_type_keyring)
@@ -402,8 +407,8 @@
continue;
/* key must have search permissions */
- if (!key_task_permission(make_key_ref(key, possessed),
- context, KEY_SEARCH))
+ if (key_task_permission(make_key_ref(key, possessed),
+ context, KEY_SEARCH) < 0)
continue;
/* we set a different error code if we find a negative key */
@@ -430,7 +435,7 @@
continue;
if (!key_task_permission(make_key_ref(key, possessed),
- context, KEY_SEARCH))
+ context, KEY_SEARCH) < 0)
continue;
/* stack the current position */
@@ -521,7 +526,7 @@
(!key->type->match ||
key->type->match(key, description)) &&
key_permission(make_key_ref(key, possessed),
- perm) &&
+ perm) < 0 &&
!test_bit(KEY_FLAG_REVOKED, &key->flags)
)
goto found;
@@ -617,7 +622,7 @@
continue;
if (!key_permission(make_key_ref(keyring, 0),
- KEY_SEARCH))
+ KEY_SEARCH) < 0)
continue;
/* found a potential candidate, but we still need to
diff --git a/security/keys/permission.c b/security/keys/permission.c
index 03db073..e7f579c 100644
--- a/security/keys/permission.c
+++ b/security/keys/permission.c
@@ -10,6 +10,7 @@
*/
#include <linux/module.h>
+#include <linux/security.h>
#include "internal.h"
/*****************************************************************************/
@@ -63,7 +64,11 @@
kperm = kperm & perm & KEY_ALL;
- return kperm == perm;
+ if (kperm != perm)
+ return -EACCES;
+
+ /* let LSM be the final arbiter */
+ return security_key_permission(key_ref, context, perm);
} /* end key_task_permission() */
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index d42d215..566b1cc 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -39,7 +39,7 @@
.type = &key_type_keyring,
.user = &root_key_user,
.sem = __RWSEM_INITIALIZER(root_user_keyring.sem),
- .perm = KEY_POS_ALL | KEY_USR_ALL,
+ .perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
.flags = 1 << KEY_FLAG_INSTANTIATED,
.description = "_uid.0",
#ifdef KEY_DEBUGGING
@@ -54,7 +54,7 @@
.type = &key_type_keyring,
.user = &root_key_user,
.sem = __RWSEM_INITIALIZER(root_session_keyring.sem),
- .perm = KEY_POS_ALL | KEY_USR_ALL,
+ .perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
.flags = 1 << KEY_FLAG_INSTANTIATED,
.description = "_uid_ses.0",
#ifdef KEY_DEBUGGING
@@ -666,9 +666,8 @@
goto invalid_key;
/* check the permissions */
- ret = -EACCES;
-
- if (!key_task_permission(key_ref, context, perm))
+ ret = key_task_permission(key_ref, context, perm);
+ if (ret < 0)
goto invalid_key;
error: