Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756382AbcCBSby (ORCPT ); Wed, 2 Mar 2016 13:31:54 -0500 Received: from mail.kernel.org ([198.145.29.136]:48348 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756147AbcCBSbv (ORCPT ); Wed, 2 Mar 2016 13:31:51 -0500 From: Jaegeuk Kim To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, tytso@mit.edu Cc: Jaegeuk Kim , Michael Halcrow , Ildar Muslukhov Subject: [PATCH 02/10] fs crypto: add crypto.c for encrypt/decrypt functions Date: Wed, 2 Mar 2016 10:31:10 -0800 Message-Id: <1456943478-11107-3-git-send-email-jaegeuk@kernel.org> X-Mailer: git-send-email 2.6.3 In-Reply-To: <1456943478-11107-1-git-send-email-jaegeuk@kernel.org> References: <1456943478-11107-1-git-send-email-jaegeuk@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 16379 Lines: 609 This patch adds crypto.c supporting encrypting and decrypting functions. 1. IO preparation: - fscrypt_get_ctx / fscrypt_release_ctx 2. before IOs: - fscrypt_encrypt_page - fscrypt_decrypt_page - fscrypt_zeroout_range 3. after IOs: - fscrypt_decrypt_bio_pages - fscrypt_pullback_bio_page - fscrypt_restore_control_page Signed-off-by: Michael Halcrow Signed-off-by: Ildar Muslukhov Signed-off-by: Theodore Ts'o Signed-off-by: Jaegeuk Kim --- fs/crypto/crypto.c | 507 +++++++++++++++++++++++++++++++++++++++++++++++ include/linux/fscrypto.h | 60 ++++++ 2 files changed, 567 insertions(+) create mode 100644 fs/crypto/crypto.c diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c new file mode 100644 index 0000000..928a34b --- /dev/null +++ b/fs/crypto/crypto.c @@ -0,0 +1,507 @@ +/* + * This contains encryption functions for per-file encryption. + * + * Copyright (C) 2015, Google, Inc. + * Copyright (C) 2015, Motorola Mobility + * + * Written by Michael Halcrow, 2014. + * + * Filename encryption additions + * Uday Savagaonkar, 2014 + * Encryption policy handling additions + * Ildar Muslukhov, 2014 + * Add fscrypt_pullback_bio_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 +#include +#include +#include +#include +#include +#include +#include +#include + +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 *fscrypt_bounce_page_pool = NULL; + +static LIST_HEAD(fscrypt_free_ctxs); +static DEFINE_SPINLOCK(fscrypt_ctx_lock); + +static struct workqueue_struct *fscrypt_read_workqueue; +static DEFINE_MUTEX(fscrypt_init_mutex); + +static struct kmem_cache *fscrypt_ctx_cachep; +struct kmem_cache *fscrypt_info_cachep; + +/** + * fscrypt_release_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 fscrypt_release_ctx(struct fscrypt_ctx *ctx) +{ + unsigned long flags; + + if (ctx->flags & FS_WRITE_PATH_FL && ctx->w.bounce_page) { + mempool_free(ctx->w.bounce_page, fscrypt_bounce_page_pool); + ctx->w.bounce_page = NULL; + } + ctx->w.control_page = NULL; + if (ctx->flags & FS_CTX_REQUIRES_FREE_ENCRYPT_FL) { + kmem_cache_free(fscrypt_ctx_cachep, ctx); + } else { + spin_lock_irqsave(&fscrypt_ctx_lock, flags); + list_add(&ctx->free_list, &fscrypt_free_ctxs); + spin_unlock_irqrestore(&fscrypt_ctx_lock, flags); + } +} +EXPORT_SYMBOL(fscrypt_release_ctx); + +/** + * fscrypt_get_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 fscrypt_ctx *fscrypt_get_ctx(struct inode *inode) +{ + struct fscrypt_ctx *ctx = NULL; + struct fscrypt_info *ci = inode->i_crypt_info; + unsigned long flags; + + 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(&fscrypt_ctx_lock, flags); + ctx = list_first_entry_or_null(&fscrypt_free_ctxs, + struct fscrypt_ctx, free_list); + if (ctx) + list_del(&ctx->free_list); + spin_unlock_irqrestore(&fscrypt_ctx_lock, flags); + if (!ctx) { + ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, GFP_NOFS); + if (!ctx) + return ERR_PTR(-ENOMEM); + ctx->flags |= FS_CTX_REQUIRES_FREE_ENCRYPT_FL; + } else { + ctx->flags &= ~FS_CTX_REQUIRES_FREE_ENCRYPT_FL; + } + ctx->flags &= ~FS_WRITE_PATH_FL; + return ctx; +} +EXPORT_SYMBOL(fscrypt_get_ctx); + +/** + * fscrypt_complete() - The completion callback for page encryption + * @req: The asynchronous encryption request context + * @res: The result of the encryption operation + */ +static void fscrypt_complete(struct crypto_async_request *req, int res) +{ + struct fscrypt_completion_result *ecr = req->data; + + if (res == -EINPROGRESS) + return; + ecr->res = res; + complete(&ecr->completion); +} + +typedef enum { + FS_DECRYPT = 0, + FS_ENCRYPT, +} fscrypt_direction_t; + +static int do_page_crypto(struct inode *inode, + fscrypt_direction_t rw, pgoff_t index, + struct page *src_page, struct page *dest_page) +{ + u8 xts_tweak[FS_XTS_TWEAK_SIZE]; + struct ablkcipher_request *req = NULL; + DECLARE_FS_COMPLETION_RESULT(ecr); + struct scatterlist dst, src; + struct fscrypt_info *ci = 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, + fscrypt_complete, &ecr); + + BUILD_BUG_ON(FS_XTS_TWEAK_SIZE < sizeof(index)); + memcpy(xts_tweak, &inode->i_ino, sizeof(index)); + memset(&xts_tweak[sizeof(index)], 0, + FS_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 == FS_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; +} + +static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx) +{ + ctx->w.bounce_page = mempool_alloc(fscrypt_bounce_page_pool, + GFP_NOWAIT); + if (ctx->w.bounce_page == NULL) + return ERR_PTR(-ENOMEM); + ctx->flags |= FS_WRITE_PATH_FL; + return ctx->w.bounce_page; +} + +/** + * fscypt_encrypt_page() - 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 + * fscrypt_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 *fscrypt_encrypt_page(struct inode *inode, + struct page *plaintext_page) +{ + struct fscrypt_ctx *ctx; + struct page *ciphertext_page = NULL; + int err; + + BUG_ON(!PageLocked(plaintext_page)); + + ctx = fscrypt_get_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 errout; + + ctx->w.control_page = plaintext_page; + err = do_page_crypto(inode, FS_ENCRYPT, plaintext_page->index, + plaintext_page, ciphertext_page); + if (err) { + ciphertext_page = ERR_PTR(err); + goto errout; + } + SetPagePrivate(ciphertext_page); + set_page_private(ciphertext_page, (unsigned long)ctx); + lock_page(ciphertext_page); + return ciphertext_page; + +errout: + fscrypt_release_ctx(ctx); + return ciphertext_page; +} +EXPORT_SYMBOL(fscrypt_encrypt_page); + +/** + * f2crypt_decrypt_page() - Decrypts a page in-place + * @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 fscrypt_decrypt_page(struct page *page) +{ + BUG_ON(!PageLocked(page)); + + return do_page_crypto(page->mapping->host, + FS_DECRYPT, page->index, page, page); +} +EXPORT_SYMBOL(fscrypt_decrypt_page); + +int fscrypt_zeroout_range(struct inode *inode, pgoff_t lblk, + sector_t pblk, unsigned int len) +{ + struct fscrypt_ctx *ctx; + struct page *ciphertext_page = NULL; + struct bio *bio; + int ret, err = 0; + + BUG_ON(inode->i_sb->s_blocksize != PAGE_CACHE_SIZE); + + ctx = fscrypt_get_ctx(inode); + if (IS_ERR(ctx)) + return PTR_ERR(ctx); + + ciphertext_page = alloc_bounce_page(ctx); + if (IS_ERR(ciphertext_page)) { + err = PTR_ERR(ciphertext_page); + goto errout; + } + + while (len--) { + err = do_page_crypto(inode, FS_ENCRYPT, lblk, + ZERO_PAGE(0), ciphertext_page); + if (err) + goto errout; + + bio = bio_alloc(GFP_KERNEL, 1); + if (!bio) { + err = -ENOMEM; + goto errout; + } + bio->bi_bdev = inode->i_sb->s_bdev; + bio->bi_iter.bi_sector = + pblk << (inode->i_sb->s_blocksize_bits - 9); + ret = bio_add_page(bio, ciphertext_page, + inode->i_sb->s_blocksize, 0); + if (ret != inode->i_sb->s_blocksize) { + /* should never happen! */ + WARN_ON(1); + bio_put(bio); + err = -EIO; + goto errout; + } + err = submit_bio_wait(WRITE, bio); + if ((err == 0) && bio->bi_error) + err = -EIO; + bio_put(bio); + if (err) + goto errout; + lblk++; + pblk++; + } + err = 0; +errout: + fscrypt_release_ctx(ctx); + return err; +} +EXPORT_SYMBOL(fscrypt_zeroout_range); + +/* + * Call fscrypt_decrypt_page on every single page, reusing the encryption + * context. + */ +static void completion_pages(struct work_struct *work) +{ + struct fscrypt_ctx *ctx = + container_of(work, struct fscrypt_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 = fscrypt_decrypt_page(page); + + if (ret) { + WARN_ON_ONCE(1); + SetPageError(page); + } else { + SetPageUptodate(page); + } + unlock_page(page); + } + fscrypt_release_ctx(ctx); + bio_put(bio); +} + +void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio) +{ + INIT_WORK(&ctx->r.work, completion_pages); + ctx->r.bio = bio; + queue_work(fscrypt_read_workqueue, &ctx->r.work); +} +EXPORT_SYMBOL(fscrypt_decrypt_bio_pages); + +void fscrypt_pullback_bio_page(struct page **page, bool restore) +{ + struct fscrypt_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 fscrypt_ctx *)page_private(bounce_page); + + /* restore control page */ + *page = ctx->w.control_page; + + if (restore) + fscrypt_restore_control_page(bounce_page); +} +EXPORT_SYMBOL(fscrypt_pullback_bio_page); + +void fscrypt_restore_control_page(struct page *page) +{ + struct fscrypt_ctx *ctx; + + ctx = (struct fscrypt_ctx *)page_private(page); + set_page_private(page, (unsigned long)NULL); + ClearPagePrivate(page); + unlock_page(page); + fscrypt_release_ctx(ctx); +} +EXPORT_SYMBOL(fscrypt_restore_control_page); + +static void fscrypt_destroy(void) +{ + struct fscrypt_ctx *pos, *n; + + list_for_each_entry_safe(pos, n, &fscrypt_free_ctxs, free_list) + kmem_cache_free(fscrypt_ctx_cachep, pos); + INIT_LIST_HEAD(&fscrypt_free_ctxs); + mempool_destroy(fscrypt_bounce_page_pool); + fscrypt_bounce_page_pool = NULL; +} + +/** + * fscrypt_initialize() - allocate major buffers for fs 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 fscrypt_initialize(void) +{ + int i, res = -ENOMEM; + + if (fscrypt_bounce_page_pool) + return 0; + + mutex_lock(&fscrypt_init_mutex); + if (fscrypt_bounce_page_pool) + goto already_initialized; + + for (i = 0; i < num_prealloc_crypto_ctxs; i++) { + struct fscrypt_ctx *ctx; + + ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, GFP_NOFS); + if (!ctx) + goto fail; + list_add(&ctx->free_list, &fscrypt_free_ctxs); + } + + fscrypt_bounce_page_pool = + mempool_create_page_pool(num_prealloc_crypto_pages, 0); + if (!fscrypt_bounce_page_pool) + goto fail; + +already_initialized: + mutex_unlock(&fscrypt_init_mutex); + return 0; +fail: + fscrypt_destroy(); + mutex_unlock(&fscrypt_init_mutex); + return res; +} +EXPORT_SYMBOL(fscrypt_initialize); + +/** + * fscrypt_init() - Set up for fs encryption. + */ +int __init fscrypt_init(void) +{ + fscrypt_read_workqueue = alloc_workqueue("fscrypt_read_queue", + WQ_HIGHPRI, 0); + if (!fscrypt_read_workqueue) + goto fail; + + fscrypt_ctx_cachep = KMEM_CACHE(fscrypt_ctx, SLAB_RECLAIM_ACCOUNT); + if (!fscrypt_ctx_cachep) + goto fail_free_queue; + + fscrypt_info_cachep = KMEM_CACHE(fscrypt_info, SLAB_RECLAIM_ACCOUNT); + if (!fscrypt_info_cachep) + goto fail_free_ctx; + + return 0; + +fail_free_ctx: + kmem_cache_destroy(fscrypt_ctx_cachep); +fail_free_queue: + destroy_workqueue(fscrypt_read_workqueue); +fail: + return -ENOMEM; +} +module_init(fscrypt_init) + +/** + * fscrypt_exit() - Shutdown the fs encryption system + */ +void __exit fscrypt_exit(void) +{ + fscrypt_destroy(); + + if (fscrypt_read_workqueue) + destroy_workqueue(fscrypt_read_workqueue); + kmem_cache_destroy(fscrypt_ctx_cachep); + kmem_cache_destroy(fscrypt_info_cachep); +} +module_exit(fscrypt_exit); + +MODULE_LICENSE("GPL"); diff --git a/include/linux/fscrypto.h b/include/linux/fscrypto.h index 4d83f08..63211f9 100644 --- a/include/linux/fscrypto.h +++ b/include/linux/fscrypto.h @@ -236,4 +236,64 @@ static inline int fscrypt_has_encryption_key(struct inode *inode) return 0; #endif } + +#if IS_ENABLED(CONFIG_FS_ENCRYPTION) +/* crypto.c */ +extern struct kmem_cache *fscrypt_info_cachep; +int fscrypt_initialize(void); + +extern struct fscrypt_ctx *fscrypt_get_ctx(struct inode *); +extern void fscrypt_release_ctx(struct fscrypt_ctx *); +extern struct page *fscrypt_encrypt_page(struct inode *, struct page *); +extern int fscrypt_decrypt_page(struct page *); +extern void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *, struct bio *); +extern void fscrypt_pullback_bio_page(struct page **, bool); +extern void fscrypt_restore_control_page(struct page *); +extern int fscrypt_zeroout_range(struct inode *, pgoff_t, sector_t, + unsigned int); +#endif + +/* crypto.c */ +static inline struct fscrypt_ctx *fscrypt_notsupp_get_ctx(struct inode *i) +{ + return ERR_PTR(-EOPNOTSUPP); +} + +static inline void fscrypt_notsupp_release_ctx(struct fscrypt_ctx *c) +{ + return; +} + +static inline struct page *fscrypt_notsupp_encrypt_page(struct inode *i, + struct page *p) +{ + return ERR_PTR(-EOPNOTSUPP); +} + +static inline int fscrypt_notsupp_decrypt_page(struct page *p) +{ + return -EOPNOTSUPP; +} + +static inline void fscrypt_notsupp_decrypt_bio_pages(struct fscrypt_ctx *c, + struct bio *b) +{ + return; +} + +static inline void fscrypt_notsupp_pullback_bio_page(struct page **p, bool b) +{ + return; +} + +static inline void fscrypt_notsupp_restore_control_page(struct page *p) +{ + return; +} + +static inline int fscrypt_notsupp_zeroout_range(struct inode *i, pgoff_t p, + sector_t s, unsigned int f) +{ + return -EOPNOTSUPP; +} #endif /* _LINUX_FSCRYPTO_H */ -- 2.6.3