diff options
Diffstat (limited to 'kernel/fs/f2fs/crypto.c')
| -rw-r--r-- | kernel/fs/f2fs/crypto.c | 491 |
1 files changed, 491 insertions, 0 deletions
diff --git a/kernel/fs/f2fs/crypto.c b/kernel/fs/f2fs/crypto.c new file mode 100644 index 000000000..4a62ef14e --- /dev/null +++ b/kernel/fs/f2fs/crypto.c @@ -0,0 +1,491 @@ +/* + * 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) { + 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 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; +} |