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authorMimi Zohar <zohar@linux.vnet.ibm.com>2015-11-10 16:34:46 +0300
committerMimi Zohar <zohar@linux.vnet.ibm.com>2015-12-15 18:01:43 +0300
commitd3600bcf9d64d88dc1d189a754dcfab960ce751f (patch)
tree0db5cee0ddb99cfe1cbd7f8314653f36ddf5005f /security/keys
parent80eae209d63ac6361c7b445f7e7e41f39c044772 (diff)
downloadlinux-d3600bcf9d64d88dc1d189a754dcfab960ce751f.tar.xz
KEYS: prevent keys from being removed from specified keyrings
Userspace should not be allowed to remove keys from certain keyrings (eg. blacklist), though the keys themselves can expire. This patch defines a new key flag named KEY_FLAG_KEEP to prevent userspace from being able to unlink, revoke, invalidate or timed out a key on a keyring. When this flag is set on the keyring, all keys subsequently added are flagged. In addition, when this flag is set, the keyring itself can not be cleared. Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com> Cc: David Howells <dhowells@redhat.com>
Diffstat (limited to 'security/keys')
-rw-r--r--security/keys/key.c6
-rw-r--r--security/keys/keyctl.c56
2 files changed, 51 insertions, 11 deletions
diff --git a/security/keys/key.c b/security/keys/key.c
index ab7997ded725..09ef276c4bdc 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -429,8 +429,12 @@ static int __key_instantiate_and_link(struct key *key,
awaken = 1;
/* and link it into the destination keyring */
- if (keyring)
+ if (keyring) {
+ if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
+ set_bit(KEY_FLAG_KEEP, &key->flags);
+
__key_link(key, _edit);
+ }
/* disable the authorisation key */
if (authkey)
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index fb111eafcb89..e83ec6b9eb9d 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -358,11 +358,14 @@ error:
* and any links to the key will be automatically garbage collected after a
* certain amount of time (/proc/sys/kernel/keys/gc_delay).
*
+ * Keys with KEY_FLAG_KEEP set should not be revoked.
+ *
* If successful, 0 is returned.
*/
long keyctl_revoke_key(key_serial_t id)
{
key_ref_t key_ref;
+ struct key *key;
long ret;
key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE);
@@ -377,8 +380,13 @@ long keyctl_revoke_key(key_serial_t id)
}
}
- key_revoke(key_ref_to_ptr(key_ref));
- ret = 0;
+ key = key_ref_to_ptr(key_ref);
+ if (test_bit(KEY_FLAG_KEEP, &key->flags))
+ return -EPERM;
+ else {
+ key_revoke(key);
+ ret = 0;
+ }
key_ref_put(key_ref);
error:
@@ -392,11 +400,14 @@ error:
* The key and any links to the key will be automatically garbage collected
* immediately.
*
+ * Keys with KEY_FLAG_KEEP set should not be invalidated.
+ *
* If successful, 0 is returned.
*/
long keyctl_invalidate_key(key_serial_t id)
{
key_ref_t key_ref;
+ struct key *key;
long ret;
kenter("%d", id);
@@ -420,8 +431,13 @@ long keyctl_invalidate_key(key_serial_t id)
}
invalidate:
- key_invalidate(key_ref_to_ptr(key_ref));
- ret = 0;
+ key = key_ref_to_ptr(key_ref);
+ if (test_bit(KEY_FLAG_KEEP, &key->flags))
+ ret = -EPERM;
+ else {
+ key_invalidate(key);
+ ret = 0;
+ }
error_put:
key_ref_put(key_ref);
error:
@@ -433,12 +449,13 @@ error:
* Clear the specified keyring, creating an empty process keyring if one of the
* special keyring IDs is used.
*
- * The keyring must grant the caller Write permission for this to work. If
- * successful, 0 will be returned.
+ * The keyring must grant the caller Write permission and not have
+ * KEY_FLAG_KEEP set for this to work. If successful, 0 will be returned.
*/
long keyctl_keyring_clear(key_serial_t ringid)
{
key_ref_t keyring_ref;
+ struct key *keyring;
long ret;
keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
@@ -460,7 +477,11 @@ long keyctl_keyring_clear(key_serial_t ringid)
}
clear:
- ret = keyring_clear(key_ref_to_ptr(keyring_ref));
+ keyring = key_ref_to_ptr(keyring_ref);
+ if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
+ ret = -EPERM;
+ else
+ ret = keyring_clear(keyring);
error_put:
key_ref_put(keyring_ref);
error:
@@ -511,11 +532,14 @@ error:
* itself need not grant the caller anything. If the last link to a key is
* removed then that key will be scheduled for destruction.
*
+ * Keys or keyrings with KEY_FLAG_KEEP set should not be unlinked.
+ *
* If successful, 0 will be returned.
*/
long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
{
key_ref_t keyring_ref, key_ref;
+ struct key *keyring, *key;
long ret;
keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_WRITE);
@@ -530,7 +554,13 @@ long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
goto error2;
}
- ret = key_unlink(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
+ keyring = key_ref_to_ptr(keyring_ref);
+ key = key_ref_to_ptr(key_ref);
+ if (test_bit(KEY_FLAG_KEEP, &keyring->flags) &&
+ test_bit(KEY_FLAG_KEEP, &key->flags))
+ ret = -EPERM;
+ else
+ ret = key_unlink(keyring, key);
key_ref_put(key_ref);
error2:
@@ -1289,6 +1319,8 @@ error:
* the current time. The key and any links to the key will be automatically
* garbage collected after the timeout expires.
*
+ * Keys with KEY_FLAG_KEEP set should not be timed out.
+ *
* If successful, 0 is returned.
*/
long keyctl_set_timeout(key_serial_t id, unsigned timeout)
@@ -1320,10 +1352,14 @@ long keyctl_set_timeout(key_serial_t id, unsigned timeout)
okay:
key = key_ref_to_ptr(key_ref);
- key_set_timeout(key, timeout);
+ if (test_bit(KEY_FLAG_KEEP, &key->flags))
+ ret = -EPERM;
+ else {
+ key_set_timeout(key, timeout);
+ ret = 0;
+ }
key_put(key);
- ret = 0;
error:
return ret;
}