aboutsummaryrefslogtreecommitdiff
path: root/security
diff options
context:
space:
mode:
authorDavid Howells <dhowells@redhat.com>2006-01-08 01:02:45 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-08 20:13:53 -0800
commitcab8eb594e84b434d20412fc5a3985b0bee3ab9f (patch)
tree307dc5bf813effdcabe439a74ad2ae866516adb0 /security
parent017679c4d45783158dba1dd6f79e712c22bb3d9a (diff)
downloadlinux-linaro-stable-cab8eb594e84b434d20412fc5a3985b0bee3ab9f.tar.gz
[PATCH] keys: Discard duplicate keys from a keyring on link
Cause any links within a keyring to keys that match a key to be linked into that keyring to be discarded as a link to the new key is added. The match is contingent on the type and description strings being the same. This permits requests, adds and searches to displace negative, expired, revoked and dead keys easily. After some discussion it was concluded that duplicate valid keys should probably be discarded also as they would otherwise hide the new key. Since request_key() is intended to be the primary method by which keys are added to a keyring, duplicate valid keys wouldn't be an issue there as that function would return an existing match in preference to creating a new key. Signed-off-by: David Howells <dhowells@redhat.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Alexander Zangerl <az@bond.edu.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'security')
-rw-r--r--security/keys/keyring.c87
1 files changed, 64 insertions, 23 deletions
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index 5d22c0388b32..09d92d52ef75 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -684,15 +684,31 @@ static void keyring_link_rcu_disposal(struct rcu_head *rcu)
/*****************************************************************************/
/*
+ * dispose of a keyring list after the RCU grace period, freeing the unlinked
+ * key
+ */
+static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
+{
+ struct keyring_list *klist =
+ container_of(rcu, struct keyring_list, rcu);
+
+ key_put(klist->keys[klist->delkey]);
+ kfree(klist);
+
+} /* end keyring_unlink_rcu_disposal() */
+
+/*****************************************************************************/
+/*
* link a key into to a keyring
* - must be called with the keyring's semaphore write-locked
+ * - discard already extant link to matching key if there is one
*/
int __key_link(struct key *keyring, struct key *key)
{
struct keyring_list *klist, *nklist;
unsigned max;
size_t size;
- int ret;
+ int loop, ret;
ret = -EKEYREVOKED;
if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
@@ -714,6 +730,48 @@ int __key_link(struct key *keyring, struct key *key)
goto error2;
}
+ /* see if there's a matching key we can displace */
+ klist = keyring->payload.subscriptions;
+
+ if (klist && klist->nkeys > 0) {
+ struct key_type *type = key->type;
+
+ for (loop = klist->nkeys - 1; loop >= 0; loop--) {
+ if (klist->keys[loop]->type == type &&
+ strcmp(klist->keys[loop]->description,
+ key->description) == 0
+ ) {
+ /* found a match - replace with new key */
+ size = sizeof(struct key *) * klist->maxkeys;
+ size += sizeof(*klist);
+ BUG_ON(size > PAGE_SIZE);
+
+ ret = -ENOMEM;
+ nklist = kmalloc(size, GFP_KERNEL);
+ if (!nklist)
+ goto error2;
+
+ memcpy(nklist, klist, size);
+
+ /* replace matched key */
+ atomic_inc(&key->usage);
+ nklist->keys[loop] = key;
+
+ rcu_assign_pointer(
+ keyring->payload.subscriptions,
+ nklist);
+
+ /* dispose of the old keyring list and the
+ * displaced key */
+ klist->delkey = loop;
+ call_rcu(&klist->rcu,
+ keyring_unlink_rcu_disposal);
+
+ goto done;
+ }
+ }
+ }
+
/* check that we aren't going to overrun the user's quota */
ret = key_payload_reserve(keyring,
keyring->datalen + KEYQUOTA_LINK_BYTES);
@@ -730,8 +788,6 @@ int __key_link(struct key *keyring, struct key *key)
smp_wmb();
klist->nkeys++;
smp_wmb();
-
- ret = 0;
}
else {
/* grow the key list */
@@ -769,16 +825,16 @@ int __key_link(struct key *keyring, struct key *key)
/* dispose of the old keyring list */
if (klist)
call_rcu(&klist->rcu, keyring_link_rcu_disposal);
-
- ret = 0;
}
- error2:
+done:
+ ret = 0;
+error2:
up_write(&keyring_serialise_link_sem);
- error:
+error:
return ret;
- error3:
+error3:
/* undo the quota changes */
key_payload_reserve(keyring,
keyring->datalen - KEYQUOTA_LINK_BYTES);
@@ -809,21 +865,6 @@ EXPORT_SYMBOL(key_link);
/*****************************************************************************/
/*
- * dispose of a keyring list after the RCU grace period, freeing the unlinked
- * key
- */
-static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
-{
- struct keyring_list *klist =
- container_of(rcu, struct keyring_list, rcu);
-
- key_put(klist->keys[klist->delkey]);
- kfree(klist);
-
-} /* end keyring_unlink_rcu_disposal() */
-
-/*****************************************************************************/
-/*
* unlink the first link to a key from a keyring
*/
int key_unlink(struct key *keyring, struct key *key)