1 files changed, 284 insertions, 0 deletions
diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
new file mode 100644
index 000000000..65793f150
--- /dev/null
+++ b/mm/kasan/quarantine.c
@@ -0,0 +1,284 @@
+/*
+ * KASAN quarantine.
+ *
+ * Author: Alexander Potapenko <glider@google.com>
+ * Copyright (C) 2016 Google, Inc.
+ *
+ * Based on code by Dmitry Chernenkov.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ */
+
+#include <linux/gfp.h>
+#include <linux/hash.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/percpu.h>
+#include <linux/printk.h>
+#include <linux/shrinker.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/types.h>
+
+#include "../slab.h"
+#include "kasan.h"
+
+/* Data structure and operations for quarantine queues. */
+
+/*
+ * Each queue is a signle-linked list, which also stores the total size of
+ * objects inside of it.
+ */
+struct qlist_head {
+	struct qlist_node *head;
+	struct qlist_node *tail;
+	size_t bytes;
+};
+
+#define QLIST_INIT { NULL, NULL, 0 }
+
+static bool qlist_empty(struct qlist_head *q)
+{
+	return !q->head;
+}
+
+static void qlist_init(struct qlist_head *q)
+{
+	q->head = q->tail = NULL;
+	q->bytes = 0;
+}
+
+static void qlist_put(struct qlist_head *q, struct qlist_node *qlink,
+		size_t size)
+{
+	if (unlikely(qlist_empty(q)))
+		q->head = qlink;
+	else
+		q->tail->next = qlink;
+	q->tail = qlink;
+	qlink->next = NULL;
+	q->bytes += size;
+}
+
+static void qlist_move_all(struct qlist_head *from, struct qlist_head *to)
+{
+	if (unlikely(qlist_empty(from)))
+		return;
+
+	if (qlist_empty(to)) {
+		*to = *from;
+		qlist_init(from);
+		return;
+	}
+
+	to->tail->next = from->head;
+	to->tail = from->tail;
+	to->bytes += from->bytes;
+
+	qlist_init(from);
+}
+
+static void qlist_move(struct qlist_head *from, struct qlist_node *last,
+		struct qlist_head *to, size_t size)
+{
+	if (unlikely(last == from->tail)) {
+		qlist_move_all(from, to);
+		return;
+	}
+	if (qlist_empty(to))
+		to->head = from->head;
+	else
+		to->tail->next = from->head;
+	to->tail = last;
+	from->head = last->next;
+	last->next = NULL;
+	from->bytes -= size;
+	to->bytes += size;
+}
+
+
+/*
+ * The object quarantine consists of per-cpu queues and a global queue,
+ * guarded by quarantine_lock.
+ */
+static DEFINE_PER_CPU(struct qlist_head, cpu_quarantine);
+
+static struct qlist_head global_quarantine;
+static DEFINE_SPINLOCK(quarantine_lock);
+
+/* Maximum size of the global queue. */
+static unsigned long quarantine_size;
+
+/*
+ * The fraction of physical memory the quarantine is allowed to occupy.
+ * Quarantine doesn't support memory shrinker with SLAB allocator, so we keep
+ * the ratio low to avoid OOM.
+ */
+#define QUARANTINE_FRACTION 32
+
+#define QUARANTINE_LOW_SIZE (READ_ONCE(quarantine_size) * 3 / 4)
+#define QUARANTINE_PERCPU_SIZE (1 << 20)
+
+static struct kmem_cache *qlink_to_cache(struct qlist_node *qlink)
+{
+	return virt_to_head_page(qlink)->slab_cache;
+}
+
+static void *qlink_to_object(struct qlist_node *qlink, struct kmem_cache *cache)
+{
+	struct kasan_free_meta *free_info =
+		container_of(qlink, struct kasan_free_meta,
+			     quarantine_link);
+
+	return ((void *)free_info) - cache->kasan_info.free_meta_offset;
+}
+
+static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
+{
+	void *object = qlink_to_object(qlink, cache);
+	struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
+	unsigned long flags;
+
+	local_irq_save(flags);
+	alloc_info->state = KASAN_STATE_FREE;
+	___cache_free(cache, object, _THIS_IP_);
+	local_irq_restore(flags);
+}
+
+static void qlist_free_all(struct qlist_head *q, struct kmem_cache *cache)
+{
+	struct qlist_node *qlink;
+
+	if (unlikely(qlist_empty(q)))
+		return;
+
+	qlink = q->head;
+	while (qlink) {
+		struct kmem_cache *obj_cache =
+			cache ? cache :	qlink_to_cache(qlink);
+		struct qlist_node *next = qlink->next;
+
+		qlink_free(qlink, obj_cache);
+		qlink = next;
+	}
+	qlist_init(q);
+}
+
+void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache)
+{
+	unsigned long flags;
+	struct qlist_head *q;
+	struct qlist_head temp = QLIST_INIT;
+
+	local_irq_save(flags);
+
+	q = this_cpu_ptr(&cpu_quarantine);
+	qlist_put(q, &info->quarantine_link, cache->size);
+	if (unlikely(q->bytes > QUARANTINE_PERCPU_SIZE))
+		qlist_move_all(q, &temp);
+
+	local_irq_restore(flags);
+
+	if (unlikely(!qlist_empty(&temp))) {
+		spin_lock_irqsave(&quarantine_lock, flags);
+		qlist_move_all(&temp, &global_quarantine);
+		spin_unlock_irqrestore(&quarantine_lock, flags);
+	}
+}
+
+void quarantine_reduce(void)
+{
+	size_t new_quarantine_size;
+	unsigned long flags;
+	struct qlist_head to_free = QLIST_INIT;
+	size_t size_to_free = 0;
+	struct qlist_node *last;
+
+	if (likely(READ_ONCE(global_quarantine.bytes) <=
+		   READ_ONCE(quarantine_size)))
+		return;
+
+	spin_lock_irqsave(&quarantine_lock, flags);
+
+	/*
+	 * Update quarantine size in case of hotplug. Allocate a fraction of
+	 * the installed memory to quarantine minus per-cpu queue limits.
+	 */
+	new_quarantine_size = (READ_ONCE(totalram_pages) << PAGE_SHIFT) /
+		QUARANTINE_FRACTION;
+	new_quarantine_size -= QUARANTINE_PERCPU_SIZE * num_online_cpus();
+	WRITE_ONCE(quarantine_size, new_quarantine_size);
+
+	last = global_quarantine.head;
+	while (last) {
+		struct kmem_cache *cache = qlink_to_cache(last);
+
+		size_to_free += cache->size;
+		if (!last->next || size_to_free >
+		    global_quarantine.bytes - QUARANTINE_LOW_SIZE)
+			break;
+		last = last->next;
+	}
+	qlist_move(&global_quarantine, last, &to_free, size_to_free);
+
+	spin_unlock_irqrestore(&quarantine_lock, flags);
+
+	qlist_free_all(&to_free, NULL);
+}
+
+static void qlist_move_cache(struct qlist_head *from,
+				   struct qlist_head *to,
+				   struct kmem_cache *cache)
+{
+	struct qlist_node *curr;
+
+	if (unlikely(qlist_empty(from)))
+		return;
+
+	curr = from->head;
+	qlist_init(from);
+	while (curr) {
+		struct qlist_node *next = curr->next;
+		struct kmem_cache *obj_cache = qlink_to_cache(curr);
+
+		if (obj_cache == cache)
+			qlist_put(to, curr, obj_cache->size);
+		else
+			qlist_put(from, curr, obj_cache->size);
+
+		curr = next;
+	}
+}
+
+static void per_cpu_remove_cache(void *arg)
+{
+	struct kmem_cache *cache = arg;
+	struct qlist_head to_free = QLIST_INIT;
+	struct qlist_head *q;
+
+	q = this_cpu_ptr(&cpu_quarantine);
+	qlist_move_cache(q, &to_free, cache);
+	qlist_free_all(&to_free, cache);
+}
+
+void quarantine_remove_cache(struct kmem_cache *cache)
+{
+	unsigned long flags;
+	struct qlist_head to_free = QLIST_INIT;
+
+	on_each_cpu(per_cpu_remove_cache, cache, 1);
+
+	spin_lock_irqsave(&quarantine_lock, flags);
+	qlist_move_cache(&global_quarantine, &to_free, cache);
+	spin_unlock_irqrestore(&quarantine_lock, flags);
+
+	qlist_free_all(&to_free, cache);
+}