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Date: Fri, 12 Jan 2018 19:41:27 +0530
From: Chandan Rajendra <chandan@...ux.vnet.ibm.com>
To: linux-ext4@...r.kernel.org
Cc: Chandan Rajendra <chandan@...ux.vnet.ibm.com>,
linux-fsdevel@...r.kernel.org, tytso@....edu
Subject: [RFC PATCH 6/8] ext4: encrypt blocks whose size is less than page size
This commit adds code to encrypt all file blocks mapped by page.
Signed-off-by: Chandan Rajendra <chandan@...ux.vnet.ibm.com>
---
fs/crypto/crypto.c | 80 ++++++++++++++++++++++++++---------------
fs/ext4/page-io.c | 58 ++++++++++++++++++++----------
include/linux/fscrypt_notsupp.h | 15 ++++----
include/linux/fscrypt_supp.h | 11 ++++--
4 files changed, 108 insertions(+), 56 deletions(-)
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 732a786..52ad5cf 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -226,15 +226,16 @@ struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
* Return: A page with the encrypted content on success. Else, an
* error value or NULL.
*/
-struct page *fscrypt_encrypt_page(const struct inode *inode,
- struct page *page,
- unsigned int len,
- unsigned int offs,
- u64 lblk_num, gfp_t gfp_flags)
-
+int fscrypt_encrypt_page(const struct inode *inode,
+ struct page *page,
+ unsigned int len,
+ unsigned int offs,
+ u64 lblk_num,
+ struct fscrypt_ctx **ctx,
+ struct page **ciphertext_page,
+ gfp_t gfp_flags)
{
- struct fscrypt_ctx *ctx;
- struct page *ciphertext_page = page;
+ int mark_pg_private = 0;
int err;
BUG_ON(len % FS_CRYPTO_BLOCK_SIZE != 0);
@@ -242,41 +243,64 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
if (inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES) {
/* with inplace-encryption we just encrypt the page */
err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk_num, page,
- ciphertext_page, len, offs,
+ page, len, offs,
gfp_flags);
if (err)
- return ERR_PTR(err);
+ return err;
- return ciphertext_page;
+ *ciphertext_page = page;
+
+ return 0;
}
BUG_ON(!PageLocked(page));
- ctx = fscrypt_get_ctx(inode, gfp_flags);
- if (IS_ERR(ctx))
- return (struct page *)ctx;
+ if (!*ctx) {
+ BUG_ON(*ciphertext_page);
+ *ctx = fscrypt_get_ctx(inode, gfp_flags);
+ if (IS_ERR(*ctx))
+ return PTR_ERR(*ctx);
+
+ (*ctx)->w.control_page = page;
+ } else {
+ BUG_ON(!*ciphertext_page);
+ }
+
+ if (!*ciphertext_page) {
+ /* The encryption operation will require a bounce page. */
+ *ciphertext_page = fscrypt_alloc_bounce_page(*ctx, gfp_flags);
+ if (IS_ERR(*ciphertext_page)) {
+ err = PTR_ERR(*ciphertext_page);
+ *ciphertext_page = NULL;
+ goto errout;
+ }
+ mark_pg_private = 1;
+ }
- /* The encryption operation will require a bounce page. */
- ciphertext_page = fscrypt_alloc_bounce_page(ctx, gfp_flags);
- if (IS_ERR(ciphertext_page))
- goto errout;
- ctx->w.control_page = page;
err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk_num,
- page, ciphertext_page, len, offs,
+ page, *ciphertext_page, len, offs,
gfp_flags);
- if (err) {
- ciphertext_page = ERR_PTR(err);
+ if (err)
goto errout;
+
+ if (mark_pg_private) {
+ SetPagePrivate(*ciphertext_page);
+ set_page_private(*ciphertext_page, (unsigned long)(*ctx));
+ lock_page(*ciphertext_page);
}
- SetPagePrivate(ciphertext_page);
- set_page_private(ciphertext_page, (unsigned long)ctx);
- lock_page(ciphertext_page);
- return ciphertext_page;
+
+ return 0;
errout:
- fscrypt_release_ctx(ctx);
- return ciphertext_page;
+ if (*ciphertext_page && PagePrivate(*ciphertext_page)) {
+ set_page_private(*ciphertext_page, (unsigned long)NULL);
+ ClearPagePrivate(*ciphertext_page);
+ unlock_page(*ciphertext_page);
+ }
+
+ fscrypt_release_ctx(*ctx);
+ return err;
}
EXPORT_SYMBOL(fscrypt_encrypt_page);
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index db75901..9828d77 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -415,7 +415,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
struct writeback_control *wbc,
bool keep_towrite)
{
- struct page *data_page = NULL;
+ struct page *ciphertext_page = NULL;
struct inode *inode = page->mapping->host;
unsigned block_start;
struct buffer_head *bh, *head;
@@ -475,36 +475,56 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
nr_to_submit++;
} while ((bh = bh->b_this_page) != head);
- bh = head = page_buffers(page);
if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode) &&
nr_to_submit) {
+ struct fscrypt_ctx *ctx;
+ u64 blk_nr;
gfp_t gfp_flags = GFP_NOFS;
- retry_encrypt:
- data_page = fscrypt_encrypt_page(inode, page, PAGE_SIZE, 0,
- page->index, gfp_flags);
- if (IS_ERR(data_page)) {
- ret = PTR_ERR(data_page);
- if (ret == -ENOMEM && wbc->sync_mode == WB_SYNC_ALL) {
- if (io->io_bio) {
- ext4_io_submit(io);
- congestion_wait(BLK_RW_ASYNC, HZ/50);
+ bh = head = page_buffers(page);
+ blk_nr = page->index << (PAGE_SHIFT - inode->i_blkbits);
+ ctx = NULL;
+ ciphertext_page = NULL;
+
+ do {
+ if (!buffer_async_write(bh))
+ continue;
+ retry_encrypt:
+ ret = fscrypt_encrypt_page(inode, page, bh->b_size,
+ bh_offset(bh),
+ blk_nr, &ctx,
+ &ciphertext_page,
+ gfp_flags);
+ if (ret) {
+ if (ret == -ENOMEM
+ && wbc->sync_mode == WB_SYNC_ALL) {
+ if (io->io_bio) {
+ ext4_io_submit(io);
+ congestion_wait(BLK_RW_ASYNC,
+ HZ/50);
+ }
+ gfp_flags |= __GFP_NOFAIL;
+ bh = head = page_buffers(page);
+ blk_nr = page->index
+ << (PAGE_SHIFT - inode->i_blkbits);
+ ctx = NULL;
+ ciphertext_page = NULL;
+ goto retry_encrypt;
}
- gfp_flags |= __GFP_NOFAIL;
- goto retry_encrypt;
+ ciphertext_page = NULL;
+ goto out;
}
- data_page = NULL;
- goto out;
- }
+ } while (++blk_nr, (bh = bh->b_this_page) != head);
}
+ bh = head = page_buffers(page);
/* Now submit buffers to write */
do {
if (!buffer_async_write(bh))
continue;
ret = io_submit_add_bh(io, inode,
- data_page ? data_page : page, bh);
+ ciphertext_page ? ciphertext_page : page, bh);
if (ret) {
/*
* We only get here on ENOMEM. Not much else
@@ -520,8 +540,8 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
/* Error stopped previous loop? Clean up buffers... */
if (ret) {
out:
- if (data_page)
- fscrypt_restore_control_page(data_page);
+ if (ciphertext_page && !nr_submitted)
+ fscrypt_restore_control_page(ciphertext_page);
printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret);
redirty_page_for_writepage(wbc, page);
do {
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index 63e5880..019ddce 100644
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h
@@ -26,13 +26,16 @@ static inline void fscrypt_release_ctx(struct fscrypt_ctx *ctx)
return;
}
-static inline struct page *fscrypt_encrypt_page(const struct inode *inode,
- struct page *page,
- unsigned int len,
- unsigned int offs,
- u64 lblk_num, gfp_t gfp_flags)
+static inline int fscrypt_encrypt_page(const struct inode *inode,
+ struct page *page,
+ unsigned int len,
+ unsigned int offs,
+ u64 lblk_num,
+ struct fscrypt_ctx **ctx,
+ struct page **ciphertext_page,
+ gfp_t gfp_flags)
{
- return ERR_PTR(-EOPNOTSUPP);
+ return -EOPNOTSUPP;
}
static inline int fscrypt_decrypt_page(const struct inode *inode,
diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
index cf9e9fc..983d06f 100644
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h
@@ -15,9 +15,14 @@
extern struct kmem_cache *fscrypt_info_cachep;
extern struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *, gfp_t);
extern void fscrypt_release_ctx(struct fscrypt_ctx *);
-extern struct page *fscrypt_encrypt_page(const struct inode *, struct page *,
- unsigned int, unsigned int,
- u64, gfp_t);
+extern int fscrypt_encrypt_page(const struct inode *inode,
+ struct page *page,
+ unsigned int len,
+ unsigned int offs,
+ u64 lblk_num,
+ struct fscrypt_ctx **ctx,
+ struct page **ciphertext_page,
+ gfp_t gfp_flags);
extern int fscrypt_decrypt_page(const struct inode *, struct page *, unsigned int,
unsigned int, u64);
extern void fscrypt_restore_control_page(struct page *);
--
2.9.5
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