2015-04-21 04:52:47 +02:00
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/*
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* linux/fs/f2fs/crypto.c
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*
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* Copied from linux/fs/ext4/crypto.c
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*
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* Copyright (C) 2015, Google, Inc.
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* Copyright (C) 2015, Motorola Mobility
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*
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* This contains encryption functions for f2fs
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*
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* Written by Michael Halcrow, 2014.
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*
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* Filename encryption additions
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* Uday Savagaonkar, 2014
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* Encryption policy handling additions
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* Ildar Muslukhov, 2014
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* Remove ext4_encrypted_zeroout(),
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* add f2fs_restore_and_release_control_page()
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* Jaegeuk Kim, 2015.
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*
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* This has not yet undergone a rigorous security audit.
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*
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* The usage of AES-XTS should conform to recommendations in NIST
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* Special Publication 800-38E and IEEE P1619/D16.
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*/
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#include <crypto/hash.h>
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#include <crypto/sha.h>
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#include <keys/user-type.h>
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#include <keys/encrypted-type.h>
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#include <linux/crypto.h>
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#include <linux/ecryptfs.h>
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#include <linux/gfp.h>
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#include <linux/kernel.h>
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#include <linux/key.h>
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#include <linux/list.h>
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#include <linux/mempool.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/random.h>
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#include <linux/scatterlist.h>
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#include <linux/spinlock_types.h>
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#include <linux/f2fs_fs.h>
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#include <linux/ratelimit.h>
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#include <linux/bio.h>
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#include "f2fs.h"
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#include "xattr.h"
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/* Encryption added and removed here! (L: */
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static unsigned int num_prealloc_crypto_pages = 32;
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static unsigned int num_prealloc_crypto_ctxs = 128;
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module_param(num_prealloc_crypto_pages, uint, 0444);
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MODULE_PARM_DESC(num_prealloc_crypto_pages,
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"Number of crypto pages to preallocate");
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module_param(num_prealloc_crypto_ctxs, uint, 0444);
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MODULE_PARM_DESC(num_prealloc_crypto_ctxs,
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"Number of crypto contexts to preallocate");
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static mempool_t *f2fs_bounce_page_pool;
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static LIST_HEAD(f2fs_free_crypto_ctxs);
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static DEFINE_SPINLOCK(f2fs_crypto_ctx_lock);
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2015-05-16 00:37:24 +02:00
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static struct workqueue_struct *f2fs_read_workqueue;
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2015-04-21 04:52:47 +02:00
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static DEFINE_MUTEX(crypto_init);
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2015-05-12 22:26:54 +02:00
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static struct kmem_cache *f2fs_crypto_ctx_cachep;
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struct kmem_cache *f2fs_crypt_info_cachep;
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2015-04-21 04:52:47 +02:00
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/**
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* f2fs_release_crypto_ctx() - Releases an encryption context
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* @ctx: The encryption context to release.
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*
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* If the encryption context was allocated from the pre-allocated pool, returns
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* it to that pool. Else, frees it.
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*
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* If there's a bounce page in the context, this frees that.
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*/
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void f2fs_release_crypto_ctx(struct f2fs_crypto_ctx *ctx)
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{
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unsigned long flags;
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2015-05-12 22:40:20 +02:00
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if (ctx->flags & F2FS_WRITE_PATH_FL && ctx->w.bounce_page) {
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2015-06-01 21:39:30 +02:00
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mempool_free(ctx->w.bounce_page, f2fs_bounce_page_pool);
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2015-05-12 22:40:20 +02:00
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ctx->w.bounce_page = NULL;
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2015-04-21 04:52:47 +02:00
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}
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2015-05-12 22:40:20 +02:00
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ctx->w.control_page = NULL;
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2015-04-21 04:52:47 +02:00
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if (ctx->flags & F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL) {
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2015-05-12 22:26:54 +02:00
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kmem_cache_free(f2fs_crypto_ctx_cachep, ctx);
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2015-04-21 04:52:47 +02:00
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} else {
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spin_lock_irqsave(&f2fs_crypto_ctx_lock, flags);
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list_add(&ctx->free_list, &f2fs_free_crypto_ctxs);
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spin_unlock_irqrestore(&f2fs_crypto_ctx_lock, flags);
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}
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}
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/**
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* f2fs_get_crypto_ctx() - Gets an encryption context
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* @inode: The inode for which we are doing the crypto
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*
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* Allocates and initializes an encryption context.
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*
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* Return: An allocated and initialized encryption context on success; error
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* value or NULL otherwise.
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*/
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struct f2fs_crypto_ctx *f2fs_get_crypto_ctx(struct inode *inode)
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{
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struct f2fs_crypto_ctx *ctx = NULL;
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unsigned long flags;
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struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
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2015-05-06 05:20:29 +02:00
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if (ci == NULL)
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2015-06-11 23:23:05 +02:00
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return ERR_PTR(-ENOKEY);
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2015-05-06 05:20:29 +02:00
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2015-04-21 04:52:47 +02:00
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/*
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* We first try getting the ctx from a free list because in
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* the common case the ctx will have an allocated and
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* initialized crypto tfm, so it's probably a worthwhile
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* optimization. For the bounce page, we first try getting it
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* from the kernel allocator because that's just about as fast
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* as getting it from a list and because a cache of free pages
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* should generally be a "last resort" option for a filesystem
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* to be able to do its job.
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*/
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spin_lock_irqsave(&f2fs_crypto_ctx_lock, flags);
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ctx = list_first_entry_or_null(&f2fs_free_crypto_ctxs,
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struct f2fs_crypto_ctx, free_list);
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if (ctx)
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list_del(&ctx->free_list);
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spin_unlock_irqrestore(&f2fs_crypto_ctx_lock, flags);
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if (!ctx) {
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2015-05-12 22:26:54 +02:00
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ctx = kmem_cache_zalloc(f2fs_crypto_ctx_cachep, GFP_NOFS);
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2015-05-20 07:26:54 +02:00
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if (!ctx)
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return ERR_PTR(-ENOMEM);
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2015-04-21 04:52:47 +02:00
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ctx->flags |= F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
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} else {
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ctx->flags &= ~F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
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}
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2015-05-12 22:40:20 +02:00
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ctx->flags &= ~F2FS_WRITE_PATH_FL;
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2015-04-21 04:52:47 +02:00
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return ctx;
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}
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/*
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* Call f2fs_decrypt on every single page, reusing the encryption
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* context.
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*/
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static void completion_pages(struct work_struct *work)
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{
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struct f2fs_crypto_ctx *ctx =
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2015-05-12 22:40:20 +02:00
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container_of(work, struct f2fs_crypto_ctx, r.work);
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struct bio *bio = ctx->r.bio;
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2015-04-21 04:52:47 +02:00
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struct bio_vec *bv;
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int i;
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bio_for_each_segment_all(bv, bio, i) {
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struct page *page = bv->bv_page;
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int ret = f2fs_decrypt(ctx, page);
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if (ret) {
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WARN_ON_ONCE(1);
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SetPageError(page);
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} else
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SetPageUptodate(page);
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unlock_page(page);
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}
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f2fs_release_crypto_ctx(ctx);
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bio_put(bio);
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}
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void f2fs_end_io_crypto_work(struct f2fs_crypto_ctx *ctx, struct bio *bio)
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{
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2015-05-12 22:40:20 +02:00
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INIT_WORK(&ctx->r.work, completion_pages);
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ctx->r.bio = bio;
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queue_work(f2fs_read_workqueue, &ctx->r.work);
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2015-04-21 04:52:47 +02:00
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}
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2015-05-16 00:37:24 +02:00
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static void f2fs_crypto_destroy(void)
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2015-04-21 04:52:47 +02:00
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{
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struct f2fs_crypto_ctx *pos, *n;
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2015-05-20 07:26:54 +02:00
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list_for_each_entry_safe(pos, n, &f2fs_free_crypto_ctxs, free_list)
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2015-05-12 22:26:54 +02:00
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kmem_cache_free(f2fs_crypto_ctx_cachep, pos);
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2015-04-21 04:52:47 +02:00
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INIT_LIST_HEAD(&f2fs_free_crypto_ctxs);
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if (f2fs_bounce_page_pool)
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mempool_destroy(f2fs_bounce_page_pool);
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f2fs_bounce_page_pool = NULL;
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}
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/**
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2015-05-16 00:37:24 +02:00
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* f2fs_crypto_initialize() - Set up for f2fs encryption.
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2015-04-21 04:52:47 +02:00
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*
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* We only call this when we start accessing encrypted files, since it
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* results in memory getting allocated that wouldn't otherwise be used.
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*
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* Return: Zero on success, non-zero otherwise.
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*/
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2015-05-16 00:37:24 +02:00
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int f2fs_crypto_initialize(void)
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2015-04-21 04:52:47 +02:00
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{
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2015-05-12 22:26:54 +02:00
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int i, res = -ENOMEM;
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2015-04-21 04:52:47 +02:00
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2015-05-16 00:37:24 +02:00
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if (f2fs_bounce_page_pool)
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return 0;
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2015-04-21 04:52:47 +02:00
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mutex_lock(&crypto_init);
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2015-05-16 00:37:24 +02:00
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if (f2fs_bounce_page_pool)
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2015-04-21 04:52:47 +02:00
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goto already_initialized;
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for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
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struct f2fs_crypto_ctx *ctx;
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2015-05-12 22:26:54 +02:00
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ctx = kmem_cache_zalloc(f2fs_crypto_ctx_cachep, GFP_KERNEL);
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2015-05-16 00:37:24 +02:00
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if (!ctx)
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2015-04-21 04:52:47 +02:00
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goto fail;
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list_add(&ctx->free_list, &f2fs_free_crypto_ctxs);
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}
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2015-05-16 00:37:24 +02:00
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/* must be allocated at the last step to avoid race condition above */
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2015-04-21 04:52:47 +02:00
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f2fs_bounce_page_pool =
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mempool_create_page_pool(num_prealloc_crypto_pages, 0);
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2015-05-16 00:37:24 +02:00
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if (!f2fs_bounce_page_pool)
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2015-04-21 04:52:47 +02:00
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goto fail;
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2015-05-16 00:37:24 +02:00
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2015-04-21 04:52:47 +02:00
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already_initialized:
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mutex_unlock(&crypto_init);
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return 0;
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fail:
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2015-05-16 00:37:24 +02:00
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f2fs_crypto_destroy();
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2015-04-21 04:52:47 +02:00
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mutex_unlock(&crypto_init);
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return res;
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}
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2015-05-16 00:37:24 +02:00
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/**
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* f2fs_exit_crypto() - Shutdown the f2fs encryption system
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*/
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void f2fs_exit_crypto(void)
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{
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f2fs_crypto_destroy();
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if (f2fs_read_workqueue)
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destroy_workqueue(f2fs_read_workqueue);
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if (f2fs_crypto_ctx_cachep)
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kmem_cache_destroy(f2fs_crypto_ctx_cachep);
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if (f2fs_crypt_info_cachep)
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kmem_cache_destroy(f2fs_crypt_info_cachep);
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}
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int __init f2fs_init_crypto(void)
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{
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int res = -ENOMEM;
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f2fs_read_workqueue = alloc_workqueue("f2fs_crypto", WQ_HIGHPRI, 0);
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if (!f2fs_read_workqueue)
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goto fail;
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f2fs_crypto_ctx_cachep = KMEM_CACHE(f2fs_crypto_ctx,
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SLAB_RECLAIM_ACCOUNT);
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if (!f2fs_crypto_ctx_cachep)
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goto fail;
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f2fs_crypt_info_cachep = KMEM_CACHE(f2fs_crypt_info,
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SLAB_RECLAIM_ACCOUNT);
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if (!f2fs_crypt_info_cachep)
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goto fail;
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return 0;
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fail:
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f2fs_exit_crypto();
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return res;
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}
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2015-04-21 04:52:47 +02:00
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void f2fs_restore_and_release_control_page(struct page **page)
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{
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struct f2fs_crypto_ctx *ctx;
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struct page *bounce_page;
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/* The bounce data pages are unmapped. */
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if ((*page)->mapping)
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return;
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/* The bounce data page is unmapped. */
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bounce_page = *page;
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ctx = (struct f2fs_crypto_ctx *)page_private(bounce_page);
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/* restore control page */
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2015-05-12 22:40:20 +02:00
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*page = ctx->w.control_page;
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2015-04-21 04:52:47 +02:00
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f2fs_restore_control_page(bounce_page);
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}
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void f2fs_restore_control_page(struct page *data_page)
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{
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struct f2fs_crypto_ctx *ctx =
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(struct f2fs_crypto_ctx *)page_private(data_page);
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set_page_private(data_page, (unsigned long)NULL);
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ClearPagePrivate(data_page);
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unlock_page(data_page);
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f2fs_release_crypto_ctx(ctx);
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}
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/**
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* f2fs_crypt_complete() - The completion callback for page encryption
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* @req: The asynchronous encryption request context
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* @res: The result of the encryption operation
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*/
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static void f2fs_crypt_complete(struct crypto_async_request *req, int res)
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{
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struct f2fs_completion_result *ecr = req->data;
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if (res == -EINPROGRESS)
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return;
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ecr->res = res;
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complete(&ecr->completion);
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}
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typedef enum {
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F2FS_DECRYPT = 0,
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|
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F2FS_ENCRYPT,
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} f2fs_direction_t;
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static int f2fs_page_crypto(struct f2fs_crypto_ctx *ctx,
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struct inode *inode,
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f2fs_direction_t rw,
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pgoff_t index,
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struct page *src_page,
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|
struct page *dest_page)
|
|
|
|
{
|
|
|
|
u8 xts_tweak[F2FS_XTS_TWEAK_SIZE];
|
|
|
|
struct ablkcipher_request *req = NULL;
|
|
|
|
DECLARE_F2FS_COMPLETION_RESULT(ecr);
|
|
|
|
struct scatterlist dst, src;
|
2015-05-20 07:26:54 +02:00
|
|
|
struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
|
|
|
|
struct crypto_ablkcipher *tfm = ci->ci_ctfm;
|
2015-04-21 04:52:47 +02:00
|
|
|
int res = 0;
|
|
|
|
|
2015-05-20 07:26:54 +02:00
|
|
|
req = ablkcipher_request_alloc(tfm, GFP_NOFS);
|
2015-04-21 04:52:47 +02:00
|
|
|
if (!req) {
|
|
|
|
printk_ratelimited(KERN_ERR
|
|
|
|
"%s: crypto_request_alloc() failed\n",
|
|
|
|
__func__);
|
|
|
|
return -ENOMEM;
|
|
|
|
}
|
|
|
|
ablkcipher_request_set_callback(
|
|
|
|
req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
|
|
|
|
f2fs_crypt_complete, &ecr);
|
|
|
|
|
|
|
|
BUILD_BUG_ON(F2FS_XTS_TWEAK_SIZE < sizeof(index));
|
|
|
|
memcpy(xts_tweak, &index, sizeof(index));
|
|
|
|
memset(&xts_tweak[sizeof(index)], 0,
|
|
|
|
F2FS_XTS_TWEAK_SIZE - sizeof(index));
|
|
|
|
|
|
|
|
sg_init_table(&dst, 1);
|
|
|
|
sg_set_page(&dst, dest_page, PAGE_CACHE_SIZE, 0);
|
|
|
|
sg_init_table(&src, 1);
|
|
|
|
sg_set_page(&src, src_page, PAGE_CACHE_SIZE, 0);
|
|
|
|
ablkcipher_request_set_crypt(req, &src, &dst, PAGE_CACHE_SIZE,
|
|
|
|
xts_tweak);
|
|
|
|
if (rw == F2FS_DECRYPT)
|
|
|
|
res = crypto_ablkcipher_decrypt(req);
|
|
|
|
else
|
|
|
|
res = crypto_ablkcipher_encrypt(req);
|
|
|
|
if (res == -EINPROGRESS || res == -EBUSY) {
|
|
|
|
BUG_ON(req->base.data != &ecr);
|
|
|
|
wait_for_completion(&ecr.completion);
|
|
|
|
res = ecr.res;
|
|
|
|
}
|
|
|
|
ablkcipher_request_free(req);
|
|
|
|
if (res) {
|
|
|
|
printk_ratelimited(KERN_ERR
|
|
|
|
"%s: crypto_ablkcipher_encrypt() returned %d\n",
|
|
|
|
__func__, res);
|
|
|
|
return res;
|
|
|
|
}
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
2015-06-11 23:33:29 +02:00
|
|
|
static struct page *alloc_bounce_page(struct f2fs_crypto_ctx *ctx)
|
|
|
|
{
|
|
|
|
ctx->w.bounce_page = mempool_alloc(f2fs_bounce_page_pool, GFP_NOWAIT);
|
|
|
|
if (ctx->w.bounce_page == NULL)
|
|
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
ctx->flags |= F2FS_WRITE_PATH_FL;
|
|
|
|
return ctx->w.bounce_page;
|
|
|
|
}
|
|
|
|
|
2015-04-21 04:52:47 +02:00
|
|
|
/**
|
|
|
|
* f2fs_encrypt() - Encrypts a page
|
|
|
|
* @inode: The inode for which the encryption should take place
|
|
|
|
* @plaintext_page: The page to encrypt. Must be locked.
|
|
|
|
*
|
|
|
|
* Allocates a ciphertext page and encrypts plaintext_page into it using the ctx
|
|
|
|
* encryption context.
|
|
|
|
*
|
|
|
|
* Called on the page write path. The caller must call
|
|
|
|
* f2fs_restore_control_page() on the returned ciphertext page to
|
|
|
|
* release the bounce buffer and the encryption context.
|
|
|
|
*
|
|
|
|
* Return: An allocated page with the encrypted content on success. Else, an
|
|
|
|
* error value or NULL.
|
|
|
|
*/
|
|
|
|
struct page *f2fs_encrypt(struct inode *inode,
|
|
|
|
struct page *plaintext_page)
|
|
|
|
{
|
|
|
|
struct f2fs_crypto_ctx *ctx;
|
|
|
|
struct page *ciphertext_page = NULL;
|
|
|
|
int err;
|
|
|
|
|
|
|
|
BUG_ON(!PageLocked(plaintext_page));
|
|
|
|
|
|
|
|
ctx = f2fs_get_crypto_ctx(inode);
|
|
|
|
if (IS_ERR(ctx))
|
|
|
|
return (struct page *)ctx;
|
|
|
|
|
|
|
|
/* The encryption operation will require a bounce page. */
|
2015-06-11 23:33:29 +02:00
|
|
|
ciphertext_page = alloc_bounce_page(ctx);
|
|
|
|
if (IS_ERR(ciphertext_page))
|
2015-06-01 21:39:30 +02:00
|
|
|
goto err_out;
|
|
|
|
|
2015-05-12 22:40:20 +02:00
|
|
|
ctx->w.control_page = plaintext_page;
|
2015-04-21 04:52:47 +02:00
|
|
|
err = f2fs_page_crypto(ctx, inode, F2FS_ENCRYPT, plaintext_page->index,
|
|
|
|
plaintext_page, ciphertext_page);
|
2015-06-11 23:33:29 +02:00
|
|
|
if (err) {
|
|
|
|
ciphertext_page = ERR_PTR(err);
|
2015-06-01 21:39:30 +02:00
|
|
|
goto err_out;
|
2015-06-11 23:33:29 +02:00
|
|
|
}
|
2015-06-01 21:39:30 +02:00
|
|
|
|
2015-04-21 04:52:47 +02:00
|
|
|
SetPagePrivate(ciphertext_page);
|
|
|
|
set_page_private(ciphertext_page, (unsigned long)ctx);
|
|
|
|
lock_page(ciphertext_page);
|
|
|
|
return ciphertext_page;
|
2015-06-01 21:39:30 +02:00
|
|
|
|
|
|
|
err_out:
|
|
|
|
f2fs_release_crypto_ctx(ctx);
|
2015-06-11 23:33:29 +02:00
|
|
|
return ciphertext_page;
|
2015-04-21 04:52:47 +02:00
|
|
|
}
|
|
|
|
|
|
|
|
/**
|
|
|
|
* f2fs_decrypt() - Decrypts a page in-place
|
|
|
|
* @ctx: The encryption context.
|
|
|
|
* @page: The page to decrypt. Must be locked.
|
|
|
|
*
|
|
|
|
* Decrypts page in-place using the ctx encryption context.
|
|
|
|
*
|
|
|
|
* Called from the read completion callback.
|
|
|
|
*
|
|
|
|
* Return: Zero on success, non-zero otherwise.
|
|
|
|
*/
|
|
|
|
int f2fs_decrypt(struct f2fs_crypto_ctx *ctx, struct page *page)
|
|
|
|
{
|
|
|
|
BUG_ON(!PageLocked(page));
|
|
|
|
|
|
|
|
return f2fs_page_crypto(ctx, page->mapping->host,
|
|
|
|
F2FS_DECRYPT, page->index, page, page);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Convenience function which takes care of allocating and
|
|
|
|
* deallocating the encryption context
|
|
|
|
*/
|
|
|
|
int f2fs_decrypt_one(struct inode *inode, struct page *page)
|
|
|
|
{
|
|
|
|
struct f2fs_crypto_ctx *ctx = f2fs_get_crypto_ctx(inode);
|
|
|
|
int ret;
|
|
|
|
|
2015-06-11 23:23:05 +02:00
|
|
|
if (IS_ERR(ctx))
|
|
|
|
return PTR_ERR(ctx);
|
2015-04-21 04:52:47 +02:00
|
|
|
ret = f2fs_decrypt(ctx, page);
|
|
|
|
f2fs_release_crypto_ctx(ctx);
|
|
|
|
return ret;
|
|
|
|
}
|
|
|
|
|
|
|
|
bool f2fs_valid_contents_enc_mode(uint32_t mode)
|
|
|
|
{
|
|
|
|
return (mode == F2FS_ENCRYPTION_MODE_AES_256_XTS);
|
|
|
|
}
|
|
|
|
|
|
|
|
/**
|
|
|
|
* f2fs_validate_encryption_key_size() - Validate the encryption key size
|
|
|
|
* @mode: The key mode.
|
|
|
|
* @size: The key size to validate.
|
|
|
|
*
|
|
|
|
* Return: The validated key size for @mode. Zero if invalid.
|
|
|
|
*/
|
|
|
|
uint32_t f2fs_validate_encryption_key_size(uint32_t mode, uint32_t size)
|
|
|
|
{
|
|
|
|
if (size == f2fs_encryption_key_size(mode))
|
|
|
|
return size;
|
|
|
|
return 0;
|
|
|
|
}
|