Merge branch 'for-linus3' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6

* 'for-linus3' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6:
  SELinux: inline selinux_is_enabled in !CONFIG_SECURITY_SELINUX
  KEYS: Fix garbage collector
  KEYS: Unlock tasklist when exiting early from keyctl_session_to_parent
  CRED: Allow put_cred() to cope with a NULL groups list
  SELinux: flush the avc before disabling SELinux
  SELinux: seperate avc_cache flushing
  Creds: creds->security can be NULL is selinux is disabled

include/linux/cred.h

@@ -15,6 +15,7 @@
 #include <linux/capability.h>
 #include <linux/init.h>
 #include <linux/key.h>
+#include <linux/selinux.h>
 #include <asm/atomic.h>
 
 struct user_struct;
@@ -182,11 +183,13 @@ static inline bool creds_are_invalid(const struct cred *cred)
 	if (atomic_read(&cred->usage) < atomic_read(&cred->subscribers))
 		return true;
 #ifdef CONFIG_SECURITY_SELINUX
-	if ((unsigned long) cred->security < PAGE_SIZE)
-		return true;
-	if ((*(u32*)cred->security & 0xffffff00) ==
-	    (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))
-		return true;
+	if (selinux_is_enabled()) {
+		if ((unsigned long) cred->security < PAGE_SIZE)
+			return true;
+		if ((*(u32 *)cred->security & 0xffffff00) ==
+		    (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))
+			return true;
+	}
 #endif
 	return false;
 }

include/linux/selinux.h

@@ -61,6 +61,11 @@ void selinux_secmark_refcount_inc(void);
  *     existing SECMARK targets has been removed/flushed.
  */
 void selinux_secmark_refcount_dec(void);
+
+/**
+ * selinux_is_enabled - is SELinux enabled?
+ */
+bool selinux_is_enabled(void);
 #else
 
 static inline int selinux_string_to_sid(const char *str, u32 *sid)
@@ -84,6 +89,10 @@ static inline void selinux_secmark_refcount_dec(void)
 	return;
 }
 
+static inline bool selinux_is_enabled(void)
+{
+	return false;
+}
 #endif	/* CONFIG_SECURITY_SELINUX */
 
 #endif /* _LINUX_SELINUX_H */

kernel/cred.c

@@ -147,7 +147,8 @@ static void put_cred_rcu(struct rcu_head *rcu)
 	key_put(cred->thread_keyring);
 	key_put(cred->request_key_auth);
 	release_tgcred(cred);
-	put_group_info(cred->group_info);
+	if (cred->group_info)
+		put_group_info(cred->group_info);
 	free_uid(cred->user);
 	kmem_cache_free(cred_jar, cred);
 }

security/keys/gc.c

@@ -26,8 +26,10 @@ static void key_garbage_collector(struct work_struct *);
 static DEFINE_TIMER(key_gc_timer, key_gc_timer_func, 0, 0);
 static DECLARE_WORK(key_gc_work, key_garbage_collector);
 static key_serial_t key_gc_cursor; /* the last key the gc considered */
+static bool key_gc_again;
 static unsigned long key_gc_executing;
 static time_t key_gc_next_run = LONG_MAX;
+static time_t key_gc_new_timer;
 
 /*
  * Schedule a garbage collection run
@@ -40,9 +42,7 @@ void key_schedule_gc(time_t gc_at)
 
 	kenter("%ld", gc_at - now);
 
-	gc_at += key_gc_delay;
-
-	if (now >= gc_at) {
+	if (gc_at <= now) {
 		schedule_work(&key_gc_work);
 	} else if (gc_at < key_gc_next_run) {
 		expires = jiffies + (gc_at - now) * HZ;
@@ -112,16 +112,18 @@ static void key_garbage_collector(struct work_struct *work)
 	struct rb_node *rb;
 	key_serial_t cursor;
 	struct key *key, *xkey;
-	time_t new_timer = LONG_MAX, limit;
+	time_t new_timer = LONG_MAX, limit, now;
 
-	kenter("");
+	now = current_kernel_time().tv_sec;
+	kenter("[%x,%ld]", key_gc_cursor, key_gc_new_timer - now);
 
 	if (test_and_set_bit(0, &key_gc_executing)) {
-		key_schedule_gc(current_kernel_time().tv_sec);
+		key_schedule_gc(current_kernel_time().tv_sec + 1);
+		kleave(" [busy; deferring]");
 		return;
 	}
 
-	limit = current_kernel_time().tv_sec;
+	limit = now;
 	if (limit > key_gc_delay)
 		limit -= key_gc_delay;
 	else
@@ -129,12 +131,19 @@ static void key_garbage_collector(struct work_struct *work)
 
 	spin_lock(&key_serial_lock);
 
-	if (RB_EMPTY_ROOT(&key_serial_tree))
-		goto reached_the_end;
+	if (unlikely(RB_EMPTY_ROOT(&key_serial_tree))) {
+		spin_unlock(&key_serial_lock);
+		clear_bit(0, &key_gc_executing);
+		return;
+	}
 
 	cursor = key_gc_cursor;
 	if (cursor < 0)
 		cursor = 0;
+	if (cursor > 0)
+		new_timer = key_gc_new_timer;
+	else
+		key_gc_again = false;
 
 	/* find the first key above the cursor */
 	key = NULL;
@@ -160,35 +169,50 @@ static void key_garbage_collector(struct work_struct *work)
 
 	/* trawl through the keys looking for keyrings */
 	for (;;) {
-		if (key->expiry > 0 && key->expiry < new_timer)
+		if (key->expiry > now && key->expiry < new_timer) {
+			kdebug("will expire %x in %ld",
+			       key_serial(key), key->expiry - now);
 			new_timer = key->expiry;
+		}
 
 		if (key->type == &key_type_keyring &&
-		    key_gc_keyring(key, limit)) {
-			/* the gc ate our lock */
-			schedule_work(&key_gc_work);
-			goto no_unlock;
-		}
+		    key_gc_keyring(key, limit))
+			/* the gc had to release our lock so that the keyring
+			 * could be modified, so we have to get it again */
+			goto gc_released_our_lock;
 
 		rb = rb_next(&key->serial_node);
-		if (!rb) {
-			key_gc_cursor = 0;
-			break;
-		}
+		if (!rb)
+			goto reached_the_end;
 		key = rb_entry(rb, struct key, serial_node);
 	}
 
-out:
-	spin_unlock(&key_serial_lock);
-no_unlock:
+gc_released_our_lock:
+	kdebug("gc_released_our_lock");
+	key_gc_new_timer = new_timer;
+	key_gc_again = true;
 	clear_bit(0, &key_gc_executing);
-	if (new_timer < LONG_MAX)
-		key_schedule_gc(new_timer);
-
-	kleave("");
+	schedule_work(&key_gc_work);
+	kleave(" [continue]");
 	return;
 
+	/* when we reach the end of the run, we set the timer for the next one */
 reached_the_end:
+	kdebug("reached_the_end");
+	spin_unlock(&key_serial_lock);
+	key_gc_new_timer = new_timer;
 	key_gc_cursor = 0;
-	goto out;
+	clear_bit(0, &key_gc_executing);
+
+	if (key_gc_again) {
+		/* there may have been a key that expired whilst we were
+		 * scanning, so if we discarded any links we should do another
+		 * scan */
+		new_timer = now + 1;
+		key_schedule_gc(new_timer);
+	} else if (new_timer < LONG_MAX) {
+		new_timer += key_gc_delay;
+		key_schedule_gc(new_timer);
+	}
+	kleave(" [end]");
 }

security/keys/key.c

@@ -500,7 +500,7 @@ int key_negate_and_link(struct key *key,
 		set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
 		now = current_kernel_time();
 		key->expiry = now.tv_sec + timeout;
-		key_schedule_gc(key->expiry);
+		key_schedule_gc(key->expiry + key_gc_delay);
 
 		if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
 			awaken = 1;
@@ -909,7 +909,7 @@ void key_revoke(struct key *key)
 	time = now.tv_sec;
 	if (key->revoked_at == 0 || key->revoked_at > time) {
 		key->revoked_at = time;
-		key_schedule_gc(key->revoked_at);
+		key_schedule_gc(key->revoked_at + key_gc_delay);
 	}
 
 	up_write(&key->sem);

security/keys/keyctl.c

@@ -1115,7 +1115,7 @@ long keyctl_set_timeout(key_serial_t id, unsigned timeout)
 	}
 
 	key->expiry = expiry;
-	key_schedule_gc(key->expiry);
+	key_schedule_gc(key->expiry + key_gc_delay);
 
 	up_write(&key->sem);
 	key_put(key);
@@ -1319,6 +1319,7 @@ long keyctl_session_to_parent(void)
 already_same:
 	ret = 0;
 not_permitted:
+	write_unlock_irq(&tasklist_lock);
 	put_cred(cred);
 	return ret;
 

security/keys/keyring.c

@@ -1019,18 +1019,18 @@ void keyring_gc(struct key *keyring, time_t limit)
 	struct key *key;
 	int loop, keep, max;
 
-	kenter("%x", key_serial(keyring));
+	kenter("{%x,%s}", key_serial(keyring), keyring->description);
 
 	down_write(&keyring->sem);
 
 	klist = keyring->payload.subscriptions;
 	if (!klist)
-		goto just_return;
+		goto no_klist;
 
 	/* 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(klist->keys[loop], limit))
 			keep++;
 
 	if (keep == klist->nkeys)
@@ -1041,7 +1041,7 @@ void keyring_gc(struct key *keyring, time_t limit)
 	new = kmalloc(sizeof(struct keyring_list) + max * sizeof(struct key *),
 		      GFP_KERNEL);
 	if (!new)
-		goto just_return;
+		goto nomem;
 	new->maxkeys = max;
 	new->nkeys = 0;
 	new->delkey = 0;
@@ -1081,7 +1081,21 @@ void keyring_gc(struct key *keyring, time_t limit)
 discard_new:
 	new->nkeys = keep;
 	keyring_clear_rcu_disposal(&new->rcu);
+	up_write(&keyring->sem);
+	kleave(" [discard]");
+	return;
+
 just_return:
 	up_write(&keyring->sem);
-	kleave(" [no]");
+	kleave(" [no dead]");
+	return;
+
+no_klist:
+	up_write(&keyring->sem);
+	kleave(" [no_klist]");
+	return;
+
+nomem:
+	up_write(&keyring->sem);
+	kleave(" [oom]");
 }

security/selinux/avc.c

@@ -709,18 +709,16 @@ out:
 }
 
 /**
- * avc_ss_reset - Flush the cache and revalidate migrated permissions.
- * @seqno: policy sequence number
+ * avc_flush - Flush the cache
  */
-int avc_ss_reset(u32 seqno)
+static void avc_flush(void)
 {
-	struct avc_callback_node *c;
-	int i, rc = 0, tmprc;
-	unsigned long flag;
-	struct avc_node *node;
 	struct hlist_head *head;
 	struct hlist_node *next;
+	struct avc_node *node;
 	spinlock_t *lock;
+	unsigned long flag;
+	int i;
 
 	for (i = 0; i < AVC_CACHE_SLOTS; i++) {
 		head = &avc_cache.slots[i];
@@ -737,6 +735,18 @@ int avc_ss_reset(u32 seqno)
 		rcu_read_unlock();
 		spin_unlock_irqrestore(lock, flag);
 	}
+}
+
+/**
+ * avc_ss_reset - Flush the cache and revalidate migrated permissions.
+ * @seqno: policy sequence number
+ */
+int avc_ss_reset(u32 seqno)
+{
+	struct avc_callback_node *c;
+	int rc = 0, tmprc;
+
+	avc_flush();
 
 	for (c = avc_callbacks; c; c = c->next) {
 		if (c->events & AVC_CALLBACK_RESET) {
@@ -858,6 +868,8 @@ u32 avc_policy_seqno(void)
 
 void avc_disable(void)
 {
+	avc_flush();
+	synchronize_rcu();
 	if (avc_node_cachep)
 		kmem_cache_destroy(avc_node_cachep);
 }

security/selinux/exports.c

@@ -63,3 +63,9 @@ void selinux_secmark_refcount_dec(void)
 	atomic_dec(&selinux_secmark_refcount);
 }
 EXPORT_SYMBOL_GPL(selinux_secmark_refcount_dec);
+
+bool selinux_is_enabled(void)
+{
+	return selinux_enabled;
+}
+EXPORT_SYMBOL_GPL(selinux_is_enabled);