ext4 crypto: implement the ext4 encryption write path
Pulls block_write_begin() into fs/ext4/inode.c because it might need
to do a low-level read of the existing data, in which case we need to
decrypt it.
Signed-off-by: Michael Halcrow <mhalcrow@google.com>
Signed-off-by: Ildar Muslukhov <ildarm@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 74580ea..973816b 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3122,6 +3122,9 @@
ee_len = ext4_ext_get_actual_len(ex);
ee_pblock = ext4_ext_pblock(ex);
+ if (ext4_encrypted_inode(inode))
+ return ext4_encrypted_zeroout(inode, ex);
+
ret = sb_issue_zeroout(inode->i_sb, ee_pblock, ee_len, GFP_NOFS);
if (ret > 0)
ret = 0;
@@ -4898,6 +4901,20 @@
ext4_lblk_t lblk;
unsigned int blkbits = inode->i_blkbits;
+ /*
+ * Encrypted inodes can't handle collapse range or insert
+ * range since we would need to re-encrypt blocks with a
+ * different IV or XTS tweak (which are based on the logical
+ * block number).
+ *
+ * XXX It's not clear why zero range isn't working, but we'll
+ * leave it disabled for encrypted inodes for now. This is a
+ * bug we should fix....
+ */
+ if (ext4_encrypted_inode(inode) &&
+ (mode & (FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE)))
+ return -EOPNOTSUPP;
+
/* Return error if mode is not supported */
if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE))
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 6ab6f63..247737e 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -996,6 +996,11 @@
ei->i_block_group = group;
ei->i_last_alloc_group = ~0;
+ /* If the directory encrypted, then we should encrypt the inode. */
+ if ((S_ISDIR(mode) || S_ISREG(mode) || S_ISLNK(mode)) &&
+ ext4_encrypted_inode(dir))
+ ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT);
+
ext4_set_inode_flags(inode);
if (IS_DIRSYNC(inode))
ext4_handle_sync(handle);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index cd30091..7c4527e 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -886,6 +886,95 @@
static int ext4_get_block_write_nolock(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create);
+
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
+ get_block_t *get_block)
+{
+ unsigned from = pos & (PAGE_CACHE_SIZE - 1);
+ unsigned to = from + len;
+ struct inode *inode = page->mapping->host;
+ unsigned block_start, block_end;
+ sector_t block;
+ int err = 0;
+ unsigned blocksize = inode->i_sb->s_blocksize;
+ unsigned bbits;
+ struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
+ bool decrypt = false;
+
+ BUG_ON(!PageLocked(page));
+ BUG_ON(from > PAGE_CACHE_SIZE);
+ BUG_ON(to > PAGE_CACHE_SIZE);
+ BUG_ON(from > to);
+
+ if (!page_has_buffers(page))
+ create_empty_buffers(page, blocksize, 0);
+ head = page_buffers(page);
+ bbits = ilog2(blocksize);
+ block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
+
+ for (bh = head, block_start = 0; bh != head || !block_start;
+ block++, block_start = block_end, bh = bh->b_this_page) {
+ block_end = block_start + blocksize;
+ if (block_end <= from || block_start >= to) {
+ if (PageUptodate(page)) {
+ if (!buffer_uptodate(bh))
+ set_buffer_uptodate(bh);
+ }
+ continue;
+ }
+ if (buffer_new(bh))
+ clear_buffer_new(bh);
+ if (!buffer_mapped(bh)) {
+ WARN_ON(bh->b_size != blocksize);
+ err = get_block(inode, block, bh, 1);
+ if (err)
+ break;
+ if (buffer_new(bh)) {
+ unmap_underlying_metadata(bh->b_bdev,
+ bh->b_blocknr);
+ if (PageUptodate(page)) {
+ clear_buffer_new(bh);
+ set_buffer_uptodate(bh);
+ mark_buffer_dirty(bh);
+ continue;
+ }
+ if (block_end > to || block_start < from)
+ zero_user_segments(page, to, block_end,
+ block_start, from);
+ continue;
+ }
+ }
+ if (PageUptodate(page)) {
+ if (!buffer_uptodate(bh))
+ set_buffer_uptodate(bh);
+ continue;
+ }
+ if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
+ !buffer_unwritten(bh) &&
+ (block_start < from || block_end > to)) {
+ ll_rw_block(READ, 1, &bh);
+ *wait_bh++ = bh;
+ decrypt = ext4_encrypted_inode(inode) &&
+ S_ISREG(inode->i_mode);
+ }
+ }
+ /*
+ * If we issued read requests, let them complete.
+ */
+ while (wait_bh > wait) {
+ wait_on_buffer(*--wait_bh);
+ if (!buffer_uptodate(*wait_bh))
+ err = -EIO;
+ }
+ if (unlikely(err))
+ page_zero_new_buffers(page, from, to);
+ else if (decrypt)
+ err = ext4_decrypt_one(inode, page);
+ return err;
+}
+#endif
+
static int ext4_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
@@ -948,11 +1037,19 @@
/* In case writeback began while the page was unlocked */
wait_for_stable_page(page);
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+ if (ext4_should_dioread_nolock(inode))
+ ret = ext4_block_write_begin(page, pos, len,
+ ext4_get_block_write);
+ else
+ ret = ext4_block_write_begin(page, pos, len,
+ ext4_get_block);
+#else
if (ext4_should_dioread_nolock(inode))
ret = __block_write_begin(page, pos, len, ext4_get_block_write);
else
ret = __block_write_begin(page, pos, len, ext4_get_block);
-
+#endif
if (!ret && ext4_should_journal_data(inode)) {
ret = ext4_walk_page_buffers(handle, page_buffers(page),
from, to, NULL,
@@ -2574,7 +2671,12 @@
/* In case writeback began while the page was unlocked */
wait_for_stable_page(page);
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+ ret = ext4_block_write_begin(page, pos, len,
+ ext4_da_get_block_prep);
+#else
ret = __block_write_begin(page, pos, len, ext4_da_get_block_prep);
+#endif
if (ret < 0) {
unlock_page(page);
ext4_journal_stop(handle);
@@ -3032,6 +3134,9 @@
get_block_func = ext4_get_block_write;
dio_flags = DIO_LOCKING;
}
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+ BUG_ON(ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode));
+#endif
if (IS_DAX(inode))
ret = dax_do_io(rw, iocb, inode, iter, offset, get_block_func,
ext4_end_io_dio, dio_flags);
@@ -3096,6 +3201,11 @@
size_t count = iov_iter_count(iter);
ssize_t ret;
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+ if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode))
+ return 0;
+#endif
+
/*
* If we are doing data journalling we don't support O_DIRECT
*/
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 5687e47..51a5f12 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -67,6 +67,10 @@
bio_for_each_segment_all(bvec, bio, i) {
struct page *page = bvec->bv_page;
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+ struct page *data_page = NULL;
+ struct ext4_crypto_ctx *ctx = NULL;
+#endif
struct buffer_head *bh, *head;
unsigned bio_start = bvec->bv_offset;
unsigned bio_end = bio_start + bvec->bv_len;
@@ -76,6 +80,15 @@
if (!page)
continue;
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+ if (!page->mapping) {
+ /* The bounce data pages are unmapped. */
+ data_page = page;
+ ctx = (struct ext4_crypto_ctx *)page_private(data_page);
+ page = ctx->control_page;
+ }
+#endif
+
if (error) {
SetPageError(page);
set_bit(AS_EIO, &page->mapping->flags);
@@ -100,8 +113,13 @@
} while ((bh = bh->b_this_page) != head);
bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
local_irq_restore(flags);
- if (!under_io)
+ if (!under_io) {
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+ if (ctx)
+ ext4_restore_control_page(data_page);
+#endif
end_page_writeback(page);
+ }
}
}
@@ -376,6 +394,7 @@
static int io_submit_add_bh(struct ext4_io_submit *io,
struct inode *inode,
+ struct page *page,
struct buffer_head *bh)
{
int ret;
@@ -389,7 +408,7 @@
if (ret)
return ret;
}
- ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
+ ret = bio_add_page(io->io_bio, page, bh->b_size, bh_offset(bh));
if (ret != bh->b_size)
goto submit_and_retry;
io->io_next_block++;
@@ -402,6 +421,7 @@
struct writeback_control *wbc,
bool keep_towrite)
{
+ struct page *data_page = NULL;
struct inode *inode = page->mapping->host;
unsigned block_start, blocksize;
struct buffer_head *bh, *head;
@@ -461,19 +481,29 @@
set_buffer_async_write(bh);
} while ((bh = bh->b_this_page) != head);
- /* Now submit buffers to write */
bh = head = page_buffers(page);
+
+ if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode)) {
+ data_page = ext4_encrypt(inode, page);
+ if (IS_ERR(data_page)) {
+ ret = PTR_ERR(data_page);
+ data_page = NULL;
+ goto out;
+ }
+ }
+
+ /* Now submit buffers to write */
do {
if (!buffer_async_write(bh))
continue;
- ret = io_submit_add_bh(io, inode, bh);
+ ret = io_submit_add_bh(io, inode,
+ data_page ? data_page : page, bh);
if (ret) {
/*
* We only get here on ENOMEM. Not much else
* we can do but mark the page as dirty, and
* better luck next time.
*/
- redirty_page_for_writepage(wbc, page);
break;
}
nr_submitted++;
@@ -482,6 +512,11 @@
/* Error stopped previous loop? Clean up buffers... */
if (ret) {
+ out:
+ if (data_page)
+ ext4_restore_control_page(data_page);
+ printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret);
+ redirty_page_for_writepage(wbc, page);
do {
clear_buffer_async_write(bh);
bh = bh->b_this_page;