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Subject[PATCH 5/7] KEYS: keyring_serialise_link_sem is only needed for keyring->keyring links
Date
keyring_serialise_link_sem is only needed for keyring->keyring links as it's
used to prevent cycle detection from being avoided by parallel keyring
additions.

Signed-off-by: David Howells <dhowells@redhat.com>
---

security/keys/keyring.c | 16 +++++++++-------
1 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index 63385af..4dc2284 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -711,13 +711,14 @@ int __key_link(struct key *keyring, struct key *key)
if (keyring->type != &key_type_keyring)
goto error;

- /* serialise link/link calls to prevent parallel calls causing a
- * cycle when applied to two keyring in opposite orders */
- down_write(&keyring_serialise_link_sem);
-
- /* check that we aren't going to create a cycle adding one keyring to
- * another */
+ /* do some special keyring->keyring link checks */
if (key->type == &key_type_keyring) {
+ /* serialise link/link calls to prevent parallel calls causing
+ * a cycle when applied to two keyring in opposite orders */
+ down_write(&keyring_serialise_link_sem);
+
+ /* check that we aren't going to create a cycle adding one
+ * keyring to another */
ret = keyring_detect_cycle(keyring, key);
if (ret < 0)
goto error2;
@@ -817,7 +818,8 @@ int __key_link(struct key *keyring, struct key *key)
done:
ret = 0;
error2:
- up_write(&keyring_serialise_link_sem);
+ if (key->type == &key_type_keyring)
+ up_write(&keyring_serialise_link_sem);
error:
return ret;



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