aboutsummaryrefslogtreecommitdiffstats
path: root/security/keys/keyring.c
diff options
context:
space:
mode:
Diffstat (limited to 'security/keys/keyring.c')
-rw-r--r--security/keys/keyring.c95
1 files changed, 56 insertions, 39 deletions
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index d605f75292e4..459b3cc347f2 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -25,6 +25,11 @@
(keyring)->payload.subscriptions, \
rwsem_is_locked((struct rw_semaphore *)&(keyring)->sem)))
+#define rcu_deref_link_locked(klist, index, keyring) \
+ (rcu_dereference_protected( \
+ (klist)->keys[index], \
+ rwsem_is_locked((struct rw_semaphore *)&(keyring)->sem)))
+
#define KEY_LINK_FIXQUOTA 1UL
/*
@@ -138,6 +143,11 @@ static int keyring_match(const struct key *keyring, const void *description)
/*
* Clean up a keyring when it is destroyed. Unpublish its name if it had one
* and dispose of its data.
+ *
+ * The garbage collector detects the final key_put(), removes the keyring from
+ * the serial number tree and then does RCU synchronisation before coming here,
+ * so we shouldn't need to worry about code poking around here with the RCU
+ * readlock held by this time.
*/
static void keyring_destroy(struct key *keyring)
{
@@ -154,11 +164,10 @@ static void keyring_destroy(struct key *keyring)
write_unlock(&keyring_name_lock);
}
- klist = rcu_dereference_check(keyring->payload.subscriptions,
- atomic_read(&keyring->usage) == 0);
+ klist = rcu_access_pointer(keyring->payload.subscriptions);
if (klist) {
for (loop = klist->nkeys - 1; loop >= 0; loop--)
- key_put(klist->keys[loop]);
+ key_put(rcu_access_pointer(klist->keys[loop]));
kfree(klist);
}
}
@@ -214,7 +223,8 @@ static long keyring_read(const struct key *keyring,
ret = -EFAULT;
for (loop = 0; loop < klist->nkeys; loop++) {
- key = klist->keys[loop];
+ key = rcu_deref_link_locked(klist, loop,
+ keyring);
tmp = sizeof(key_serial_t);
if (tmp > buflen)
@@ -383,7 +393,7 @@ descend:
nkeys = keylist->nkeys;
smp_rmb();
for (kix = 0; kix < nkeys; kix++) {
- key = keylist->keys[kix];
+ key = rcu_dereference(keylist->keys[kix]);
kflags = key->flags;
/* ignore keys not of this type */
@@ -426,7 +436,7 @@ ascend:
nkeys = keylist->nkeys;
smp_rmb();
for (; kix < nkeys; kix++) {
- key = keylist->keys[kix];
+ key = rcu_dereference(keylist->keys[kix]);
if (key->type != &key_type_keyring)
continue;
@@ -531,8 +541,7 @@ key_ref_t __keyring_search_one(key_ref_t keyring_ref,
nkeys = klist->nkeys;
smp_rmb();
for (loop = 0; loop < nkeys ; loop++) {
- key = klist->keys[loop];
-
+ key = rcu_dereference(klist->keys[loop]);
if (key->type == ktype &&
(!key->type->match ||
key->type->match(key, description)) &&
@@ -654,7 +663,7 @@ ascend:
nkeys = keylist->nkeys;
smp_rmb();
for (; kix < nkeys; kix++) {
- key = keylist->keys[kix];
+ key = rcu_dereference(keylist->keys[kix]);
if (key == A)
goto cycle_detected;
@@ -711,7 +720,7 @@ static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
container_of(rcu, struct keyring_list, rcu);
if (klist->delkey != USHRT_MAX)
- key_put(klist->keys[klist->delkey]);
+ key_put(rcu_access_pointer(klist->keys[klist->delkey]));
kfree(klist);
}
@@ -749,24 +758,16 @@ int __key_link_begin(struct key *keyring, const struct key_type *type,
/* see if there's a matching key we can displace */
if (klist && klist->nkeys > 0) {
for (loop = klist->nkeys - 1; loop >= 0; loop--) {
- if (klist->keys[loop]->type == type &&
- strcmp(klist->keys[loop]->description,
- description) == 0
- ) {
- /* found a match - we'll replace this one with
- * the new key */
- size = sizeof(struct key *) * klist->maxkeys;
- size += sizeof(*klist);
- BUG_ON(size > PAGE_SIZE);
-
- ret = -ENOMEM;
- nklist = kmemdup(klist, size, GFP_KERNEL);
- if (!nklist)
- goto error_sem;
-
- /* note replacement slot */
- klist->delkey = nklist->delkey = loop;
- prealloc = (unsigned long)nklist;
+ struct key *key = rcu_deref_link_locked(klist, loop,
+ keyring);
+ if (key->type == type &&
+ strcmp(key->description, description) == 0) {
+ /* Found a match - we'll replace the link with
+ * one to the new key. We record the slot
+ * position.
+ */
+ klist->delkey = loop;
+ prealloc = 0;
goto done;
}
}
@@ -780,7 +781,7 @@ int __key_link_begin(struct key *keyring, const struct key_type *type,
if (klist && klist->nkeys < klist->maxkeys) {
/* there's sufficient slack space to append directly */
- nklist = NULL;
+ klist->delkey = klist->nkeys;
prealloc = KEY_LINK_FIXQUOTA;
} else {
/* grow the key list */
@@ -813,10 +814,10 @@ int __key_link_begin(struct key *keyring, const struct key_type *type,
}
/* add the key into the new space */
- nklist->keys[nklist->delkey] = NULL;
+ RCU_INIT_POINTER(nklist->keys[nklist->delkey], NULL);
+ prealloc = (unsigned long)nklist | KEY_LINK_FIXQUOTA;
}
- prealloc = (unsigned long)nklist | KEY_LINK_FIXQUOTA;
done:
*_prealloc = prealloc;
kleave(" = 0");
@@ -862,6 +863,7 @@ void __key_link(struct key *keyring, struct key *key,
unsigned long *_prealloc)
{
struct keyring_list *klist, *nklist;
+ struct key *discard;
nklist = (struct keyring_list *)(*_prealloc & ~KEY_LINK_FIXQUOTA);
*_prealloc = 0;
@@ -875,10 +877,10 @@ void __key_link(struct key *keyring, struct key *key,
/* there's a matching key we can displace or an empty slot in a newly
* allocated list we can fill */
if (nklist) {
- kdebug("replace %hu/%hu/%hu",
+ kdebug("reissue %hu/%hu/%hu",
nklist->delkey, nklist->nkeys, nklist->maxkeys);
- nklist->keys[nklist->delkey] = key;
+ RCU_INIT_POINTER(nklist->keys[nklist->delkey], key);
rcu_assign_pointer(keyring->payload.subscriptions, nklist);
@@ -889,9 +891,23 @@ void __key_link(struct key *keyring, struct key *key,
klist->delkey, klist->nkeys, klist->maxkeys);
call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
}
+ } else if (klist->delkey < klist->nkeys) {
+ kdebug("replace %hu/%hu/%hu",
+ klist->delkey, klist->nkeys, klist->maxkeys);
+
+ discard = rcu_dereference_protected(
+ klist->keys[klist->delkey],
+ rwsem_is_locked(&keyring->sem));
+ rcu_assign_pointer(klist->keys[klist->delkey], key);
+ /* The garbage collector will take care of RCU
+ * synchronisation */
+ key_put(discard);
} else {
/* there's sufficient slack space to append directly */
- klist->keys[klist->nkeys] = key;
+ kdebug("append %hu/%hu/%hu",
+ klist->delkey, klist->nkeys, klist->maxkeys);
+
+ RCU_INIT_POINTER(klist->keys[klist->delkey], key);
smp_wmb();
klist->nkeys++;
}
@@ -998,7 +1014,7 @@ int key_unlink(struct key *keyring, struct key *key)
if (klist) {
/* search the keyring for the key */
for (loop = 0; loop < klist->nkeys; loop++)
- if (klist->keys[loop] == key)
+ if (rcu_access_pointer(klist->keys[loop]) == key)
goto key_is_present;
}
@@ -1061,7 +1077,7 @@ static void keyring_clear_rcu_disposal(struct rcu_head *rcu)
klist = container_of(rcu, struct keyring_list, rcu);
for (loop = klist->nkeys - 1; loop >= 0; loop--)
- key_put(klist->keys[loop]);
+ key_put(rcu_access_pointer(klist->keys[loop]));
kfree(klist);
}
@@ -1161,7 +1177,8 @@ void keyring_gc(struct key *keyring, time_t limit)
/* work out how many subscriptions we're keeping */
keep = 0;
for (loop = klist->nkeys - 1; loop >= 0; loop--)
- if (!key_is_dead(klist->keys[loop], limit))
+ if (!key_is_dead(rcu_deref_link_locked(klist, loop, keyring),
+ limit))
keep++;
if (keep == klist->nkeys)
@@ -1182,11 +1199,11 @@ void keyring_gc(struct key *keyring, time_t limit)
*/
keep = 0;
for (loop = klist->nkeys - 1; loop >= 0; loop--) {
- key = klist->keys[loop];
+ key = rcu_deref_link_locked(klist, loop, keyring);
if (!key_is_dead(key, limit)) {
if (keep >= max)
goto discard_new;
- new->keys[keep++] = key_get(key);
+ RCU_INIT_POINTER(new->keys[keep++], key_get(key));
}
}
new->nkeys = keep;

Privacy Policy