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/*
* linux/fs/f2fs/crypto.c
*
* Copied from linux/fs/ext4/crypto.c
*
* Copyright (C) 2015, Google, Inc.
* Copyright (C) 2015, Motorola Mobility
*
* This contains encryption functions for f2fs
*
* Written by Michael Halcrow, 2014.
*
* Filename encryption additions
* Uday Savagaonkar, 2014
* Encryption policy handling additions
* Ildar Muslukhov, 2014
* Remove ext4_encrypted_zeroout(),
* add f2fs_restore_and_release_control_page()
* Jaegeuk Kim, 2015.
*
* This has not yet undergone a rigorous security audit.
*
* The usage of AES-XTS should conform to recommendations in NIST
* Special Publication 800-38E and IEEE P1619/D16.
*/
#include <crypto/hash.h>
#include <crypto/sha.h>
#include <keys/user-type.h>
#include <keys/encrypted-type.h>
#include <linux/crypto.h>
#include <linux/ecryptfs.h>
#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/key.h>
#include <linux/list.h>
#include <linux/mempool.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/random.h>
#include <linux/scatterlist.h>
#include <linux/spinlock_types.h>
#include <linux/f2fs_fs.h>
#include <linux/ratelimit.h>
#include <linux/bio.h>
#include "f2fs.h"
#include "xattr.h"
/* Encryption added and removed here! (L: */
static unsigned int num_prealloc_crypto_pages = 32;
static unsigned int num_prealloc_crypto_ctxs = 128;
module_param(num_prealloc_crypto_pages, uint, 0444);
MODULE_PARM_DESC(num_prealloc_crypto_pages,
"Number of crypto pages to preallocate");
module_param(num_prealloc_crypto_ctxs, uint, 0444);
MODULE_PARM_DESC(num_prealloc_crypto_ctxs,
"Number of crypto contexts to preallocate");
static mempool_t *f2fs_bounce_page_pool;
static LIST_HEAD(f2fs_free_crypto_ctxs);
static DEFINE_SPINLOCK(f2fs_crypto_ctx_lock);
static struct workqueue_struct *f2fs_read_workqueue;
static DEFINE_MUTEX(crypto_init);
static struct kmem_cache *f2fs_crypto_ctx_cachep;
struct kmem_cache *f2fs_crypt_info_cachep;
/**
* f2fs_release_crypto_ctx() - Releases an encryption context
* @ctx: The encryption context to release.
*
* If the encryption context was allocated from the pre-allocated pool, returns
* it to that pool. Else, frees it.
*
* If there's a bounce page in the context, this frees that.
*/
void f2fs_release_crypto_ctx(struct f2fs_crypto_ctx *ctx)
{
unsigned long flags;
if (ctx->flags & F2FS_WRITE_PATH_FL && ctx->w.bounce_page) {
mempool_free(ctx->w.bounce_page, f2fs_bounce_page_pool);
ctx->w.bounce_page = NULL;
}
ctx->w.control_page = NULL;
if (ctx->flags & F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL) {
kmem_cache_free(f2fs_crypto_ctx_cachep, ctx);
} else {
spin_lock_irqsave(&f2fs_crypto_ctx_lock, flags);
list_add(&ctx->free_list, &f2fs_free_crypto_ctxs);
spin_unlock_irqrestore(&f2fs_crypto_ctx_lock, flags);
}
}
/**
* f2fs_get_crypto_ctx() - Gets an encryption context
* @inode: The inode for which we are doing the crypto
*
* Allocates and initializes an encryption context.
*
* Return: An allocated and initialized encryption context on success; error
* value or NULL otherwise.
*/
struct f2fs_crypto_ctx *f2fs_get_crypto_ctx(struct inode *inode)
{
struct f2fs_crypto_ctx *ctx = NULL;
unsigned long flags;
struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
if (ci == NULL)
return ERR_PTR(-ENOKEY);
/*
* We first try getting the ctx from a free list because in
* the common case the ctx will have an allocated and
* initialized crypto tfm, so it's probably a worthwhile
* optimization. For the bounce page, we first try getting it
* from the kernel allocator because that's just about as fast
* as getting it from a list and because a cache of free pages
* should generally be a "last resort" option for a filesystem
* to be able to do its job.
*/
spin_lock_irqsave(&f2fs_crypto_ctx_lock, flags);
ctx = list_first_entry_or_null(&f2fs_free_crypto_ctxs,
struct f2fs_crypto_ctx, free_list);
if (ctx)
list_del(&ctx->free_list);
spin_unlock_irqrestore(&f2fs_crypto_ctx_lock, flags);
if (!ctx) {
ctx = kmem_cache_zalloc(f2fs_crypto_ctx_cachep, GFP_NOFS);
if (!ctx)
return ERR_PTR(-ENOMEM);
ctx->flags |= F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
} else {
ctx->flags &= ~F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
}
ctx->flags &= ~F2FS_WRITE_PATH_FL;
return ctx;
}
/*
* Call f2fs_decrypt on every single page, reusing the encryption
* context.
*/
static void completion_pages(struct work_struct *work)
{
struct f2fs_crypto_ctx *ctx =
container_of(work, struct f2fs_crypto_ctx, r.work);
struct bio *bio = ctx->r.bio;
struct bio_vec *bv;
int i;
bio_for_each_segment_all(bv, bio, i) {
struct page *page = bv->bv_page;
int ret = f2fs_decrypt(ctx, page);
if (ret) {
WARN_ON_ONCE(1);
SetPageError(page);
} else
SetPageUptodate(page);
unlock_page(page);
}
f2fs_release_crypto_ctx(ctx);
bio_put(bio);
}
void f2fs_end_io_crypto_work(struct f2fs_crypto_ctx *ctx, struct bio *bio)
{
INIT_WORK(&ctx->r.work, completion_pages);
ctx->r.bio = bio;
queue_work(f2fs_read_workqueue, &ctx->r.work);
}
static void f2fs_crypto_destroy(void)
{
struct f2fs_crypto_ctx *pos, *n;
list_for_each_entry_safe(pos, n, &f2fs_free_crypto_ctxs, free_list)
kmem_cache_free(f2fs_crypto_ctx_cachep, pos);
INIT_LIST_HEAD(&f2fs_free_crypto_ctxs);
if (f2fs_bounce_page_pool)
mempool_destroy(f2fs_bounce_page_pool);
f2fs_bounce_page_pool = NULL;
}
/**
* f2fs_crypto_initialize() - Set up for f2fs encryption.
*
* We only call this when we start accessing encrypted files, since it
* results in memory getting allocated that wouldn't otherwise be used.
*
* Return: Zero on success, non-zero otherwise.
*/
int f2fs_crypto_initialize(void)
{
int i, res = -ENOMEM;
if (f2fs_bounce_page_pool)
return 0;
mutex_lock(&crypto_init);
if (f2fs_bounce_page_pool)
goto already_initialized;
for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
struct f2fs_crypto_ctx *ctx;
ctx = kmem_cache_zalloc(f2fs_crypto_ctx_cachep, GFP_KERNEL);
if (!ctx)
goto fail;
list_add(&ctx->free_list, &f2fs_free_crypto_ctxs);
}
/* must be allocated at the last step to avoid race condition above */
f2fs_bounce_page_pool =
mempool_create_page_pool(num_prealloc_crypto_pages, 0);
if (!f2fs_bounce_page_pool)
goto fail;
already_initialized:
mutex_unlock(&crypto_init);
return 0;
fail:
f2fs_crypto_destroy();
mutex_unlock(&crypto_init);
return res;
}
/**
* f2fs_exit_crypto() - Shutdown the f2fs encryption system
*/
void f2fs_exit_crypto(void)
{
f2fs_crypto_destroy();
if (f2fs_read_workqueue)
destroy_workqueue(f2fs_read_workqueue);
if (f2fs_crypto_ctx_cachep)
kmem_cache_destroy(f2fs_crypto_ctx_cachep);
if (f2fs_crypt_info_cachep)
kmem_cache_destroy(f2fs_crypt_info_cachep);
}
int __init f2fs_init_crypto(void)
{
int res = -ENOMEM;
f2fs_read_workqueue = alloc_workqueue("f2fs_crypto", WQ_HIGHPRI, 0);
if (!f2fs_read_workqueue)
goto fail;
f2fs_crypto_ctx_cachep = KMEM_CACHE(f2fs_crypto_ctx,
SLAB_RECLAIM_ACCOUNT);
if (!f2fs_crypto_ctx_cachep)
goto fail;
f2fs_crypt_info_cachep = KMEM_CACHE(f2fs_crypt_info,
SLAB_RECLAIM_ACCOUNT);
if (!f2fs_crypt_info_cachep)
goto fail;
return 0;
fail:
f2fs_exit_crypto();
return res;
}
void f2fs_restore_and_release_control_page(struct page **page)
{
struct f2fs_crypto_ctx *ctx;
struct page *bounce_page;
/* The bounce data pages are unmapped. */
if ((*page)->mapping)
return;
/* The bounce data page is unmapped. */
bounce_page = *page;
ctx = (struct f2fs_crypto_ctx *)page_private(bounce_page);
/* restore control page */
*page = ctx->w.control_page;
f2fs_restore_control_page(bounce_page);
}
void f2fs_restore_control_page(struct page *data_page)
{
struct f2fs_crypto_ctx *ctx =
(struct f2fs_crypto_ctx *)page_private(data_page);
set_page_private(data_page, (unsigned long)NULL);
ClearPagePrivate(data_page);
unlock_page(data_page);
f2fs_release_crypto_ctx(ctx);
}
/**
* f2fs_crypt_complete() - The completion callback for page encryption
* @req: The asynchronous encryption request context
* @res: The result of the encryption operation
*/
static void f2fs_crypt_complete(struct crypto_async_request *req, int res)
{
struct f2fs_completion_result *ecr = req->data;
if
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