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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 (res == -EINPROGRESS)
- return;
- ecr->res = res;
- complete(&ecr->completion);
- }
- typedef enum {
- F2FS_DECRYPT = 0,
- F2FS_ENCRYPT,
- } f2fs_direction_t;
- static int f2fs_page_crypto(struct f2fs_crypto_ctx *ctx,
- struct inode *inode,
- f2fs_direction_t rw,
- pgoff_t index,
- struct page *src_page,
- 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;
- struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
- struct crypto_ablkcipher *tfm = ci->ci_ctfm;
- int res = 0;
- req = ablkcipher_request_alloc(tfm, GFP_NOFS);
- 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) {
- 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;
- }
- 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;
- }
- /**
- * 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. */
- ciphertext_page = alloc_bounce_page(ctx);
- if (IS_ERR(ciphertext_page))
- goto err_out;
- ctx->w.control_page = plaintext_page;
- err = f2fs_page_crypto(ctx, inode, F2FS_ENCRYPT, plaintext_page->index,
- plaintext_page, ciphertext_page);
- if (err) {
- ciphertext_page = ERR_PTR(err);
- goto err_out;
- }
- SetPagePrivate(ciphertext_page);
- set_page_private(ciphertext_page, (unsigned long)ctx);
- lock_page(ciphertext_page);
- return ciphertext_page;
- err_out:
- f2fs_release_crypto_ctx(ctx);
- return ciphertext_page;
- }
- /**
- * 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;
- if (IS_ERR(ctx))
- return PTR_ERR(ctx);
- 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;
- }
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