Commit 2058f83a authored by Michael Halcrow's avatar Michael Halcrow Committed by Theodore Ts'o

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: default avatarMichael Halcrow <mhalcrow@google.com>
Signed-off-by: default avatarIldar Muslukhov <ildarm@google.com>
Signed-off-by: Theodore Ts'o's avatarTheodore Ts'o <tytso@mit.edu>
parent dde680ce
......@@ -3122,6 +3122,9 @@ static int ext4_ext_zeroout(struct inode *inode, struct ext4_extent *ex)
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 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
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))
......
......@@ -996,6 +996,11 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir,
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);
......
......@@ -886,6 +886,95 @@ int do_journal_get_write_access(handle_t *handle,
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 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping,
/* 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 @@ static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
/* 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 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
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 @@ static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
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
*/
......
......@@ -67,6 +67,10 @@ static void ext4_finish_bio(struct bio *bio)
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 @@ static void ext4_finish_bio(struct bio *bio)
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 @@ static void ext4_finish_bio(struct bio *bio)
} 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_init_bio(struct ext4_io_submit *io,
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 @@ static int io_submit_add_bh(struct ext4_io_submit *io,
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 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
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 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
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 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
/* 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;
......
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