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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
commit | 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch) | |
tree | a94efe259b9009378be6d90eb30d2b019d95c194 /mm/kasan/quarantine.c | |
parent | Initial commit. (diff) | |
download | linux-5d1646d90e1f2cceb9f0828f4b28318cd0ec7744.tar.xz linux-5d1646d90e1f2cceb9f0828f4b28318cd0ec7744.zip |
Adding upstream version 5.10.209.upstream/5.10.209
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | mm/kasan/quarantine.c | 376 |
1 files changed, 376 insertions, 0 deletions
diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c new file mode 100644 index 000000000..622193846 --- /dev/null +++ b/mm/kasan/quarantine.c @@ -0,0 +1,376 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * 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/srcu.h> +#include <linux/string.h> +#include <linux/types.h> +#include <linux/cpuhotplug.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; + bool offline; +}; + +#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); +} + +#define QUARANTINE_PERCPU_SIZE (1 << 20) +#define QUARANTINE_BATCHES \ + (1024 > 4 * CONFIG_NR_CPUS ? 1024 : 4 * CONFIG_NR_CPUS) + +/* + * 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); + +/* Round-robin FIFO array of batches. */ +static struct qlist_head global_quarantine[QUARANTINE_BATCHES]; +static int quarantine_head; +static int quarantine_tail; +/* Total size of all objects in global_quarantine across all batches. */ +static unsigned long quarantine_size; +static DEFINE_RAW_SPINLOCK(quarantine_lock); +DEFINE_STATIC_SRCU(remove_cache_srcu); + +/* Maximum size of the global queue. */ +static unsigned long quarantine_max_size; + +/* + * Target size of a batch in global_quarantine. + * Usually equal to QUARANTINE_PERCPU_SIZE unless we have too much RAM. + */ +static unsigned long quarantine_batch_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 + +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); + unsigned long flags; + + if (IS_ENABLED(CONFIG_SLAB)) + local_irq_save(flags); + + *(u8 *)kasan_mem_to_shadow(object) = KASAN_KMALLOC_FREE; + ___cache_free(cache, object, _THIS_IP_); + + if (IS_ENABLED(CONFIG_SLAB)) + 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; + + /* + * Note: irq must be disabled until after we move the batch to the + * global quarantine. Otherwise quarantine_remove_cache() can miss + * some objects belonging to the cache if they are in our local temp + * list. quarantine_remove_cache() executes on_each_cpu() at the + * beginning which ensures that it either sees the objects in per-cpu + * lists or in the global quarantine. + */ + local_irq_save(flags); + + q = this_cpu_ptr(&cpu_quarantine); + if (q->offline) { + local_irq_restore(flags); + return; + } + qlist_put(q, &info->quarantine_link, cache->size); + if (unlikely(q->bytes > QUARANTINE_PERCPU_SIZE)) { + qlist_move_all(q, &temp); + + raw_spin_lock(&quarantine_lock); + WRITE_ONCE(quarantine_size, quarantine_size + temp.bytes); + qlist_move_all(&temp, &global_quarantine[quarantine_tail]); + if (global_quarantine[quarantine_tail].bytes >= + READ_ONCE(quarantine_batch_size)) { + int new_tail; + + new_tail = quarantine_tail + 1; + if (new_tail == QUARANTINE_BATCHES) + new_tail = 0; + if (new_tail != quarantine_head) + quarantine_tail = new_tail; + } + raw_spin_unlock(&quarantine_lock); + } + + local_irq_restore(flags); +} + +void quarantine_reduce(void) +{ + size_t total_size, new_quarantine_size, percpu_quarantines; + unsigned long flags; + int srcu_idx; + struct qlist_head to_free = QLIST_INIT; + + if (likely(READ_ONCE(quarantine_size) <= + READ_ONCE(quarantine_max_size))) + return; + + /* + * srcu critical section ensures that quarantine_remove_cache() + * will not miss objects belonging to the cache while they are in our + * local to_free list. srcu is chosen because (1) it gives us private + * grace period domain that does not interfere with anything else, + * and (2) it allows synchronize_srcu() to return without waiting + * if there are no pending read critical sections (which is the + * expected case). + */ + srcu_idx = srcu_read_lock(&remove_cache_srcu); + raw_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. + */ + total_size = (totalram_pages() << PAGE_SHIFT) / + QUARANTINE_FRACTION; + percpu_quarantines = QUARANTINE_PERCPU_SIZE * num_online_cpus(); + new_quarantine_size = (total_size < percpu_quarantines) ? + 0 : total_size - percpu_quarantines; + WRITE_ONCE(quarantine_max_size, new_quarantine_size); + /* Aim at consuming at most 1/2 of slots in quarantine. */ + WRITE_ONCE(quarantine_batch_size, max((size_t)QUARANTINE_PERCPU_SIZE, + 2 * total_size / QUARANTINE_BATCHES)); + + if (likely(quarantine_size > quarantine_max_size)) { + qlist_move_all(&global_quarantine[quarantine_head], &to_free); + WRITE_ONCE(quarantine_size, quarantine_size - to_free.bytes); + quarantine_head++; + if (quarantine_head == QUARANTINE_BATCHES) + quarantine_head = 0; + } + + raw_spin_unlock_irqrestore(&quarantine_lock, flags); + + qlist_free_all(&to_free, NULL); + srcu_read_unlock(&remove_cache_srcu, srcu_idx); +} + +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); + /* + * Ensure the ordering between the writing to q->offline and + * per_cpu_remove_cache. Prevent cpu_quarantine from being corrupted + * by interrupt. + */ + if (READ_ONCE(q->offline)) + return; + qlist_move_cache(q, &to_free, cache); + qlist_free_all(&to_free, cache); +} + +/* Free all quarantined objects belonging to cache. */ +void quarantine_remove_cache(struct kmem_cache *cache) +{ + unsigned long flags, i; + struct qlist_head to_free = QLIST_INIT; + + /* + * Must be careful to not miss any objects that are being moved from + * per-cpu list to the global quarantine in quarantine_put(), + * nor objects being freed in quarantine_reduce(). on_each_cpu() + * achieves the first goal, while synchronize_srcu() achieves the + * second. + */ + on_each_cpu(per_cpu_remove_cache, cache, 1); + + raw_spin_lock_irqsave(&quarantine_lock, flags); + for (i = 0; i < QUARANTINE_BATCHES; i++) { + if (qlist_empty(&global_quarantine[i])) + continue; + qlist_move_cache(&global_quarantine[i], &to_free, cache); + /* Scanning whole quarantine can take a while. */ + raw_spin_unlock_irqrestore(&quarantine_lock, flags); + cond_resched(); + raw_spin_lock_irqsave(&quarantine_lock, flags); + } + raw_spin_unlock_irqrestore(&quarantine_lock, flags); + + qlist_free_all(&to_free, cache); + + synchronize_srcu(&remove_cache_srcu); +} + +static int kasan_cpu_online(unsigned int cpu) +{ + this_cpu_ptr(&cpu_quarantine)->offline = false; + return 0; +} + +static int kasan_cpu_offline(unsigned int cpu) +{ + struct qlist_head *q; + + q = this_cpu_ptr(&cpu_quarantine); + /* Ensure the ordering between the writing to q->offline and + * qlist_free_all. Otherwise, cpu_quarantine may be corrupted + * by interrupt. + */ + WRITE_ONCE(q->offline, true); + barrier(); + qlist_free_all(q, NULL); + return 0; +} + +static int __init kasan_cpu_quarantine_init(void) +{ + int ret = 0; + + ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mm/kasan:online", + kasan_cpu_online, kasan_cpu_offline); + if (ret < 0) + pr_err("kasan cpu quarantine register failed [%d]\n", ret); + return ret; +} +late_initcall(kasan_cpu_quarantine_init); |