ext4 crypto: migrate into vfs's crypto engine

This patch removes the most parts of internal crypto codes.
And then, it modifies and adds some ext4-specific crypt codes to use the generic
facility.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 0 insertions, 536 deletions

diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
deleted file mode 100644
index 6a6c27373b54..000000000000
--- a/fs/ext4/crypto.c
+++ /dev/null
@@ -1,536 +0,0 @@
-/*
- * linux/fs/ext4/crypto.c
- *
- * Copyright (C) 2015, Google, Inc.
- *
- * This contains encryption functions for ext4
- *
- * Written by Michael Halcrow, 2014.
- *
- * Filename encryption additions
- *	Uday Savagaonkar, 2014
- * Encryption policy handling additions
- *	Ildar Muslukhov, 2014
- *
- * 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/skcipher.h>
-#include <keys/user-type.h>
-#include <keys/encrypted-type.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/namei.h>
-
-#include "ext4_extents.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 *ext4_bounce_page_pool;
-
-static LIST_HEAD(ext4_free_crypto_ctxs);
-static DEFINE_SPINLOCK(ext4_crypto_ctx_lock);
-
-static struct kmem_cache *ext4_crypto_ctx_cachep;
-struct kmem_cache *ext4_crypt_info_cachep;
-
-/**
- * ext4_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 ext4_release_crypto_ctx(struct ext4_crypto_ctx *ctx)
-{
-	unsigned long flags;
-
-	if (ctx->flags & EXT4_WRITE_PATH_FL && ctx->w.bounce_page)
-		mempool_free(ctx->w.bounce_page, ext4_bounce_page_pool);
-	ctx->w.bounce_page = NULL;
-	ctx->w.control_page = NULL;
-	if (ctx->flags & EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL) {
-		kmem_cache_free(ext4_crypto_ctx_cachep, ctx);
-	} else {
-		spin_lock_irqsave(&ext4_crypto_ctx_lock, flags);
-		list_add(&ctx->free_list, &ext4_free_crypto_ctxs);
-		spin_unlock_irqrestore(&ext4_crypto_ctx_lock, flags);
-	}
-}
-
-/**
- * ext4_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 ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode,
-					    gfp_t gfp_flags)
-{
-	struct ext4_crypto_ctx *ctx = NULL;
-	int res = 0;
-	unsigned long flags;
-	struct ext4_crypt_info *ci = EXT4_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(&ext4_crypto_ctx_lock, flags);
-	ctx = list_first_entry_or_null(&ext4_free_crypto_ctxs,
-				       struct ext4_crypto_ctx, free_list);
-	if (ctx)
-		list_del(&ctx->free_list);
-	spin_unlock_irqrestore(&ext4_crypto_ctx_lock, flags);
-	if (!ctx) {
-		ctx = kmem_cache_zalloc(ext4_crypto_ctx_cachep, gfp_flags);
-		if (!ctx) {
-			res = -ENOMEM;
-			goto out;
-		}
-		ctx->flags |= EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL;
-	} else {
-		ctx->flags &= ~EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL;
-	}
-	ctx->flags &= ~EXT4_WRITE_PATH_FL;
-
-out:
-	if (res) {
-		if (!IS_ERR_OR_NULL(ctx))
-			ext4_release_crypto_ctx(ctx);
-		ctx = ERR_PTR(res);
-	}
-	return ctx;
-}
-
-struct workqueue_struct *ext4_read_workqueue;
-static DEFINE_MUTEX(crypto_init);
-
-/**
- * ext4_exit_crypto() - Shutdown the ext4 encryption system
- */
-void ext4_exit_crypto(void)
-{
-	struct ext4_crypto_ctx *pos, *n;
-
-	list_for_each_entry_safe(pos, n, &ext4_free_crypto_ctxs, free_list)
-		kmem_cache_free(ext4_crypto_ctx_cachep, pos);
-	INIT_LIST_HEAD(&ext4_free_crypto_ctxs);
-	if (ext4_bounce_page_pool)
-		mempool_destroy(ext4_bounce_page_pool);
-	ext4_bounce_page_pool = NULL;
-	if (ext4_read_workqueue)
-		destroy_workqueue(ext4_read_workqueue);
-	ext4_read_workqueue = NULL;
-	if (ext4_crypto_ctx_cachep)
-		kmem_cache_destroy(ext4_crypto_ctx_cachep);
-	ext4_crypto_ctx_cachep = NULL;
-	if (ext4_crypt_info_cachep)
-		kmem_cache_destroy(ext4_crypt_info_cachep);
-	ext4_crypt_info_cachep = NULL;
-}
-
-/**
- * ext4_init_crypto() - Set up for ext4 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 ext4_init_crypto(void)
-{
-	int i, res = -ENOMEM;
-
-	mutex_lock(&crypto_init);
-	if (ext4_read_workqueue)
-		goto already_initialized;
-	ext4_read_workqueue = alloc_workqueue("ext4_crypto", WQ_HIGHPRI, 0);
-	if (!ext4_read_workqueue)
-		goto fail;
-
-	ext4_crypto_ctx_cachep = KMEM_CACHE(ext4_crypto_ctx,
-					    SLAB_RECLAIM_ACCOUNT);
-	if (!ext4_crypto_ctx_cachep)
-		goto fail;
-
-	ext4_crypt_info_cachep = KMEM_CACHE(ext4_crypt_info,
-					    SLAB_RECLAIM_ACCOUNT);
-	if (!ext4_crypt_info_cachep)
-		goto fail;
-
-	for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
-		struct ext4_crypto_ctx *ctx;
-
-		ctx = kmem_cache_zalloc(ext4_crypto_ctx_cachep, GFP_NOFS);
-		if (!ctx) {
-			res = -ENOMEM;
-			goto fail;
-		}
-		list_add(&ctx->free_list, &ext4_free_crypto_ctxs);
-	}
-
-	ext4_bounce_page_pool =
-		mempool_create_page_pool(num_prealloc_crypto_pages, 0);
-	if (!ext4_bounce_page_pool) {
-		res = -ENOMEM;
-		goto fail;
-	}
-already_initialized:
-	mutex_unlock(&crypto_init);
-	return 0;
-fail:
-	ext4_exit_crypto();
-	mutex_unlock(&crypto_init);
-	return res;
-}
-
-void ext4_restore_control_page(struct page *data_page)
-{
-	struct ext4_crypto_ctx *ctx =
-		(struct ext4_crypto_ctx *)page_private(data_page);
-
-	set_page_private(data_page, (unsigned long)NULL);
-	ClearPagePrivate(data_page);
-	unlock_page(data_page);
-	ext4_release_crypto_ctx(ctx);
-}
-
-/**
- * ext4_crypt_complete() - The completion callback for page encryption
- * @req: The asynchronous encryption request context
- * @res: The result of the encryption operation
- */
-static void ext4_crypt_complete(struct crypto_async_request *req, int res)
-{
-	struct ext4_completion_result *ecr = req->data;
-
-	if (res == -EINPROGRESS)
-		return;
-	ecr->res = res;
-	complete(&ecr->completion);
-}
-
-typedef enum {
-	EXT4_DECRYPT = 0,
-	EXT4_ENCRYPT,
-} ext4_direction_t;
-
-static int ext4_page_crypto(struct inode *inode,
-			    ext4_direction_t rw,
-			    pgoff_t index,
-			    struct page *src_page,
-			    struct page *dest_page,
-			    gfp_t gfp_flags)
-
-{
-	u8 xts_tweak[EXT4_XTS_TWEAK_SIZE];
-	struct skcipher_request *req = NULL;
-	DECLARE_EXT4_COMPLETION_RESULT(ecr);
-	struct scatterlist dst, src;
-	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
-	struct crypto_skcipher *tfm = ci->ci_ctfm;
-	int res = 0;
-
-	req = skcipher_request_alloc(tfm, gfp_flags);
-	if (!req) {
-		printk_ratelimited(KERN_ERR
-				   "%s: crypto_request_alloc() failed\n",
-				   __func__);
-		return -ENOMEM;
-	}
-	skcipher_request_set_callback(
-		req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
-		ext4_crypt_complete, &ecr);
-
-	BUILD_BUG_ON(EXT4_XTS_TWEAK_SIZE < sizeof(index));
-	memcpy(xts_tweak, &index, sizeof(index));
-	memset(&xts_tweak[sizeof(index)], 0,
-	       EXT4_XTS_TWEAK_SIZE - sizeof(index));
-
-	sg_init_table(&dst, 1);
-	sg_set_page(&dst, dest_page, PAGE_SIZE, 0);
-	sg_init_table(&src, 1);
-	sg_set_page(&src, src_page, PAGE_SIZE, 0);
-	skcipher_request_set_crypt(req, &src, &dst, PAGE_SIZE,
-				   xts_tweak);
-	if (rw == EXT4_DECRYPT)
-		res = crypto_skcipher_decrypt(req);
-	else
-		res = crypto_skcipher_encrypt(req);
-	if (res == -EINPROGRESS || res == -EBUSY) {
-		wait_for_completion(&ecr.completion);
-		res = ecr.res;
-	}
-	skcipher_request_free(req);
-	if (res) {
-		printk_ratelimited(
-			KERN_ERR
-			"%s: crypto_skcipher_encrypt() returned %d\n",
-			__func__, res);
-		return res;
-	}
-	return 0;
-}
-
-static struct page *alloc_bounce_page(struct ext4_crypto_ctx *ctx,
-				      gfp_t gfp_flags)
-{
-	ctx->w.bounce_page = mempool_alloc(ext4_bounce_page_pool, gfp_flags);
-	if (ctx->w.bounce_page == NULL)
-		return ERR_PTR(-ENOMEM);
-	ctx->flags |= EXT4_WRITE_PATH_FL;
-	return ctx->w.bounce_page;
-}
-
-/**
- * ext4_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
- * ext4_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 *ext4_encrypt(struct inode *inode,
-			  struct page *plaintext_page,
-			  gfp_t gfp_flags)
-{
-	struct ext4_crypto_ctx *ctx;
-	struct page *ciphertext_page = NULL;
-	int err;
-
-	BUG_ON(!PageLocked(plaintext_page));
-
-	ctx = ext4_get_crypto_ctx(inode, gfp_flags);
-	if (IS_ERR(ctx))
-		return (struct page *) ctx;
-
-	/* The encryption operation will require a bounce page. */
-	ciphertext_page = alloc_bounce_page(ctx, gfp_flags);
-	if (IS_ERR(ciphertext_page))
-		goto errout;
-	ctx->w.control_page = plaintext_page;
-	err = ext4_page_crypto(inode, EXT4_ENCRYPT, plaintext_page->index,
-			       plaintext_page, ciphertext_page, gfp_flags);
-	if (err) {
-		ciphertext_page = ERR_PTR(err);
-	errout:
-		ext4_release_crypto_ctx(ctx);
-		return ciphertext_page;
-	}
-	SetPagePrivate(ciphertext_page);
-	set_page_private(ciphertext_page, (unsigned long)ctx);
-	lock_page(ciphertext_page);
-	return ciphertext_page;
-}
-
-/**
- * ext4_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 ext4_decrypt(struct page *page)
-{
-	BUG_ON(!PageLocked(page));
-
-	return ext4_page_crypto(page->mapping->host, EXT4_DECRYPT,
-				page->index, page, page, GFP_NOFS);
-}
-
-int ext4_encrypted_zeroout(struct inode *inode, ext4_lblk_t lblk,
-			   ext4_fsblk_t pblk, ext4_lblk_t len)
-{
-	struct ext4_crypto_ctx	*ctx;
-	struct page		*ciphertext_page = NULL;
-	struct bio		*bio;
-	int			ret, err = 0;
-
-#if 0
-	ext4_msg(inode->i_sb, KERN_CRIT,
-		 "ext4_encrypted_zeroout ino %lu lblk %u len %u",
-		 (unsigned long) inode->i_ino, lblk, len);
-#endif
-
-	BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
-
-	ctx = ext4_get_crypto_ctx(inode, GFP_NOFS);
-	if (IS_ERR(ctx))
-		return PTR_ERR(ctx);
-
-	ciphertext_page = alloc_bounce_page(ctx, GFP_NOWAIT);
-	if (IS_ERR(ciphertext_page)) {
-		err = PTR_ERR(ciphertext_page);
-		goto errout;
-	}
-
-	while (len--) {
-		err = ext4_page_crypto(inode, EXT4_ENCRYPT, lblk,
-				       ZERO_PAGE(0), ciphertext_page,
-				       GFP_NOFS);
-		if (err)
-			goto errout;
-
-		bio = bio_alloc(GFP_NOWAIT, 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! */
-			ext4_msg(inode->i_sb, KERN_ERR,
-				 "bio_add_page failed: %d", ret);
-			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:
-	ext4_release_crypto_ctx(ctx);
-	return err;
-}
-
-bool ext4_valid_contents_enc_mode(uint32_t mode)
-{
-	return (mode == EXT4_ENCRYPTION_MODE_AES_256_XTS);
-}
-
-/**
- * ext4_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 ext4_validate_encryption_key_size(uint32_t mode, uint32_t size)
-{
-	if (size == ext4_encryption_key_size(mode))
-		return size;
-	return 0;
-}
-
-/*
- * Validate dentries for encrypted directories to make sure we aren't
- * potentially caching stale data after a key has been added or
- * removed.
- */
-static int ext4_d_revalidate(struct dentry *dentry, unsigned int flags)
-{
-	struct dentry *dir;
-	struct ext4_crypt_info *ci;
-	int dir_has_key, cached_with_key;
-
-	if (flags & LOOKUP_RCU)
-		return -ECHILD;
-
-	dir = dget_parent(dentry);
-	if (!ext4_encrypted_inode(d_inode(dir))) {
-		dput(dir);
-		return 0;
-	}
-	ci = EXT4_I(d_inode(dir))->i_crypt_info;
-	if (ci && ci->ci_keyring_key &&
-	    (ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) |
-					  (1 << KEY_FLAG_REVOKED) |
-					  (1 << KEY_FLAG_DEAD))))
-		ci = NULL;
-
-	/* this should eventually be an flag in d_flags */
-	cached_with_key = dentry->d_fsdata != NULL;
-	dir_has_key = (ci != NULL);
-	dput(dir);
-
-	/*
-	 * If the dentry was cached without the key, and it is a
-	 * negative dentry, it might be a valid name.  We can't check
-	 * if the key has since been made available due to locking
-	 * reasons, so we fail the validation so ext4_lookup() can do
-	 * this check.
-	 *
-	 * We also fail the validation if the dentry was created with
-	 * the key present, but we no longer have the key, or vice versa.
-	 */
-	if ((!cached_with_key && d_is_negative(dentry)) ||
-	    (!cached_with_key && dir_has_key) ||
-	    (cached_with_key && !dir_has_key)) {
-#if 0				/* Revalidation debug */
-		char buf[80];
-		char *cp = simple_dname(dentry, buf, sizeof(buf));
-
-		if (IS_ERR(cp))
-			cp = (char *) "???";
-		pr_err("revalidate: %s %p %d %d %d\n", cp, dentry->d_fsdata,
-		       cached_with_key, d_is_negative(dentry),
-		       dir_has_key);
-#endif
-		return 0;
-	}
-	return 1;
-}
-
-const struct dentry_operations ext4_encrypted_d_ops = {
-	.d_revalidate = ext4_d_revalidate,
-};