1 files changed, 491 insertions, 0 deletions
diff --git a/fs/f2fs/crypto.c b/fs/f2fs/crypto.c
new file mode 100644
index 000000000000..4a62ef14e932
--- /dev/null
+++ b/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;
+}