Hello,
This patchset makes ext4 support encryption on filesystems where the
filesystem block size is not equal to PAGE_SIZE. This allows e.g.
PowerPC systems to use ext4 encryption.
Most of the work for this was already done in prior kernel releases; now
the only part missing is decryption support in block_read_full_page().
Chandan Rajendra has proposed a patchset "Consolidate FS read I/O
callbacks code" [1] to address this and do various other things like
make ext4 use mpage_readpages() again, and make ext4 and f2fs share more
code. But it doesn't seem to be going anywhere.
Therefore, I propose we simply add decryption support to
block_read_full_page() for now. This is a fairly small change, and it
gets ext4 encryption with subpage-sized blocks working.
Note: to keep things simple I'm just allocating the work object from the
bi_end_io function with GFP_ATOMIC. But if people think it's necessary,
it could be changed to use preallocation like the page-based read path.
Tested with 'gce-xfstests -c ext4/encrypt_1k -g auto', using the new
"encrypt_1k" config I created. All tests pass except for those that
already fail or are excluded with the encrypt or 1k configs, and 2 tests
that try to create 1023-byte symlinks which fails since encrypted
symlinks are limited to blocksize-3 bytes. Also ran the dedicated
encryption tests using 'kvm-xfstests -c ext4/1k -g encrypt'; all pass,
including the on-disk ciphertext verification tests.
[1] https://lkml.kernel.org/linux-fsdevel/[email protected]/T/#u
Changed v1 => v2:
- Added check for S_ISREG() which technically should be there, though
it happens not to matter currently.
Chandan Rajendra (1):
ext4: Enable encryption for subpage-sized blocks
Eric Biggers (1):
fs/buffer.c: support fscrypt in block_read_full_page()
Documentation/filesystems/fscrypt.rst | 4 +--
fs/buffer.c | 48 ++++++++++++++++++++++++---
fs/ext4/super.c | 7 ----
3 files changed, 45 insertions(+), 14 deletions(-)
--
2.23.0
From: Chandan Rajendra <[email protected]>
Now that we have the code to support encryption for subpage-sized
blocks, this commit removes the conditional check in filesystem mount
code.
The commit also changes the support statement in
Documentation/filesystems/fscrypt.rst to reflect the fact that
encryption on filesystems with blocksize less than page size now works.
[EB: Tested with 'gce-xfstests -c ext4/encrypt_1k -g auto', using the
new "encrypt_1k" config I created. All tests pass except for those that
already fail or are excluded with the encrypt or 1k configs, and 2 tests
that try to create 1023-byte symlinks which fails since encrypted
symlinks are limited to blocksize-3 bytes. Also ran the dedicated
encryption tests using 'kvm-xfstests -c ext4/1k -g encrypt'; all pass,
including the on-disk ciphertext verification tests.]
Signed-off-by: Chandan Rajendra <[email protected]>
Signed-off-by: Eric Biggers <[email protected]>
---
Documentation/filesystems/fscrypt.rst | 4 ++--
fs/ext4/super.c | 7 -------
2 files changed, 2 insertions(+), 9 deletions(-)
diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst
index 8a0700af9596..b0d015a8cdc3 100644
--- a/Documentation/filesystems/fscrypt.rst
+++ b/Documentation/filesystems/fscrypt.rst
@@ -331,8 +331,8 @@ Contents encryption
-------------------
For file contents, each filesystem block is encrypted independently.
-Currently, only the case where the filesystem block size is equal to
-the system's page size (usually 4096 bytes) is supported.
+Starting from Linux kernel 5.5, encryption of filesystems with block
+size less than system's page size is supported.
Each block's IV is set to the logical block number within the file as
a little endian number, except that:
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index dd654e53ba3d..369f852bef20 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4439,13 +4439,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
}
}
- if ((DUMMY_ENCRYPTION_ENABLED(sbi) || ext4_has_feature_encrypt(sb)) &&
- (blocksize != PAGE_SIZE)) {
- ext4_msg(sb, KERN_ERR,
- "Unsupported blocksize for fs encryption");
- goto failed_mount_wq;
- }
-
if (ext4_has_feature_verity(sb) && blocksize != PAGE_SIZE) {
ext4_msg(sb, KERN_ERR, "Unsupported blocksize for fs-verity");
goto failed_mount_wq;
--
2.23.0
From: Eric Biggers <[email protected]>
After each filesystem block (as represented by a buffer_head) has been
read from disk by block_read_full_page(), decrypt it if needed. The
decryption is done on the fscrypt_read_workqueue.
This is the final change needed to support ext4 encryption with
blocksize != PAGE_SIZE, and it's a fairly small change now that
CONFIG_FS_ENCRYPTION is a bool and fs/crypto/ exposes functions to
decrypt individual blocks and to enqueue work on the fscrypt workqueue.
Don't try to add fs-verity support yet, as the fs/verity/ support layer
isn't ready for sub-page blocks yet. Just add fscrypt support for now.
Almost all the new code is compiled away when CONFIG_FS_ENCRYPTION=n.
Cc: Chandan Rajendra <[email protected]>
Signed-off-by: Eric Biggers <[email protected]>
---
fs/buffer.c | 48 +++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 43 insertions(+), 5 deletions(-)
diff --git a/fs/buffer.c b/fs/buffer.c
index 86a38b979323..d39838090b22 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -47,6 +47,7 @@
#include <linux/pagevec.h>
#include <linux/sched/mm.h>
#include <trace/events/block.h>
+#include <linux/fscrypt.h>
static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
@@ -246,10 +247,6 @@ __find_get_block_slow(struct block_device *bdev, sector_t block)
return ret;
}
-/*
- * I/O completion handler for block_read_full_page() - pages
- * which come unlocked at the end of I/O.
- */
static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
{
unsigned long flags;
@@ -307,6 +304,47 @@ static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
return;
}
+struct decrypt_bh_ctx {
+ struct work_struct work;
+ struct buffer_head *bh;
+};
+
+static void decrypt_bh(struct work_struct *work)
+{
+ struct decrypt_bh_ctx *ctx =
+ container_of(work, struct decrypt_bh_ctx, work);
+ struct buffer_head *bh = ctx->bh;
+ int err;
+
+ err = fscrypt_decrypt_pagecache_blocks(bh->b_page, bh->b_size,
+ bh_offset(bh));
+ end_buffer_async_read(bh, err == 0);
+ kfree(ctx);
+}
+
+/*
+ * I/O completion handler for block_read_full_page() - pages
+ * which come unlocked at the end of I/O.
+ */
+static void end_buffer_async_read_io(struct buffer_head *bh, int uptodate)
+{
+ /* Decrypt if needed */
+ if (uptodate && IS_ENABLED(CONFIG_FS_ENCRYPTION) &&
+ IS_ENCRYPTED(bh->b_page->mapping->host) &&
+ S_ISREG(bh->b_page->mapping->host->i_mode)) {
+ struct decrypt_bh_ctx *ctx = kmalloc(sizeof(*ctx), GFP_ATOMIC);
+
+ if (ctx) {
+ INIT_WORK(&ctx->work, decrypt_bh);
+ ctx->bh = bh;
+ fscrypt_enqueue_decrypt_work(&ctx->work);
+ return;
+ }
+ uptodate = 0;
+ }
+ end_buffer_async_read(bh, uptodate);
+}
+
/*
* Completion handler for block_write_full_page() - pages which are unlocked
* during I/O, and which have PageWriteback cleared upon I/O completion.
@@ -379,7 +417,7 @@ EXPORT_SYMBOL(end_buffer_async_write);
*/
static void mark_buffer_async_read(struct buffer_head *bh)
{
- bh->b_end_io = end_buffer_async_read;
+ bh->b_end_io = end_buffer_async_read_io;
set_buffer_async_read(bh);
}
--
2.23.0
On Wednesday, October 23, 2019 9:03 AM Eric Biggers wrote:
> Hello,
>
> This patchset makes ext4 support encryption on filesystems where the
> filesystem block size is not equal to PAGE_SIZE. This allows e.g.
> PowerPC systems to use ext4 encryption.
>
> Most of the work for this was already done in prior kernel releases; now
> the only part missing is decryption support in block_read_full_page().
> Chandan Rajendra has proposed a patchset "Consolidate FS read I/O
> callbacks code" [1] to address this and do various other things like
> make ext4 use mpage_readpages() again, and make ext4 and f2fs share more
> code. But it doesn't seem to be going anywhere.
>
> Therefore, I propose we simply add decryption support to
> block_read_full_page() for now. This is a fairly small change, and it
> gets ext4 encryption with subpage-sized blocks working.
>
> Note: to keep things simple I'm just allocating the work object from the
> bi_end_io function with GFP_ATOMIC. But if people think it's necessary,
> it could be changed to use preallocation like the page-based read path.
>
> Tested with 'gce-xfstests -c ext4/encrypt_1k -g auto', using the new
> "encrypt_1k" config I created. All tests pass except for those that
> already fail or are excluded with the encrypt or 1k configs, and 2 tests
> that try to create 1023-byte symlinks which fails since encrypted
> symlinks are limited to blocksize-3 bytes. Also ran the dedicated
> encryption tests using 'kvm-xfstests -c ext4/1k -g encrypt'; all pass,
> including the on-disk ciphertext verification tests.
I have tested this patchset on ppc64le with both 4k and 64k block size. There
were no regressions. Hence,
Tested-by: Chandan Rajendra <[email protected]>
--
chandan
On Tue, Oct 22, 2019 at 08:33:10PM -0700, Eric Biggers wrote:
> Hello,
>
> This patchset makes ext4 support encryption on filesystems where the
> filesystem block size is not equal to PAGE_SIZE. This allows e.g.
> PowerPC systems to use ext4 encryption.
>
> Most of the work for this was already done in prior kernel releases; now
> the only part missing is decryption support in block_read_full_page().
> Chandan Rajendra has proposed a patchset "Consolidate FS read I/O
> callbacks code" [1] to address this and do various other things like
> make ext4 use mpage_readpages() again, and make ext4 and f2fs share more
> code. But it doesn't seem to be going anywhere.
>
> Therefore, I propose we simply add decryption support to
> block_read_full_page() for now. This is a fairly small change, and it
> gets ext4 encryption with subpage-sized blocks working.
>
> Note: to keep things simple I'm just allocating the work object from the
> bi_end_io function with GFP_ATOMIC. But if people think it's necessary,
> it could be changed to use preallocation like the page-based read path.
>
> Tested with 'gce-xfstests -c ext4/encrypt_1k -g auto', using the new
> "encrypt_1k" config I created. All tests pass except for those that
> already fail or are excluded with the encrypt or 1k configs, and 2 tests
> that try to create 1023-byte symlinks which fails since encrypted
> symlinks are limited to blocksize-3 bytes. Also ran the dedicated
> encryption tests using 'kvm-xfstests -c ext4/1k -g encrypt'; all pass,
> including the on-disk ciphertext verification tests.
>
> [1] https://lkml.kernel.org/linux-fsdevel/[email protected]/T/#u
>
> Changed v1 => v2:
> - Added check for S_ISREG() which technically should be there, though
> it happens not to matter currently.
>
> Chandan Rajendra (1):
> ext4: Enable encryption for subpage-sized blocks
>
> Eric Biggers (1):
> fs/buffer.c: support fscrypt in block_read_full_page()
>
> Documentation/filesystems/fscrypt.rst | 4 +--
> fs/buffer.c | 48 ++++++++++++++++++++++++---
> fs/ext4/super.c | 7 ----
> 3 files changed, 45 insertions(+), 14 deletions(-)
>
Any more comments on this?
Ted, are you interested in taking this through the ext4 tree for 5.5?
- Eric
On Wed, Nov 06, 2019 at 01:54:40PM -0800, Eric Biggers wrote:
> On Tue, Oct 22, 2019 at 08:33:10PM -0700, Eric Biggers wrote:
> > Hello,
> >
> > This patchset makes ext4 support encryption on filesystems where the
> > filesystem block size is not equal to PAGE_SIZE. This allows e.g.
> > PowerPC systems to use ext4 encryption.
> >
> > Most of the work for this was already done in prior kernel releases; now
> > the only part missing is decryption support in block_read_full_page().
> > Chandan Rajendra has proposed a patchset "Consolidate FS read I/O
> > callbacks code" [1] to address this and do various other things like
> > make ext4 use mpage_readpages() again, and make ext4 and f2fs share more
> > code. But it doesn't seem to be going anywhere.
> >
> > Therefore, I propose we simply add decryption support to
> > block_read_full_page() for now. This is a fairly small change, and it
> > gets ext4 encryption with subpage-sized blocks working.
> >
> > Note: to keep things simple I'm just allocating the work object from the
> > bi_end_io function with GFP_ATOMIC. But if people think it's necessary,
> > it could be changed to use preallocation like the page-based read path.
> >
> > Tested with 'gce-xfstests -c ext4/encrypt_1k -g auto', using the new
> > "encrypt_1k" config I created. All tests pass except for those that
> > already fail or are excluded with the encrypt or 1k configs, and 2 tests
> > that try to create 1023-byte symlinks which fails since encrypted
> > symlinks are limited to blocksize-3 bytes. Also ran the dedicated
> > encryption tests using 'kvm-xfstests -c ext4/1k -g encrypt'; all pass,
> > including the on-disk ciphertext verification tests.
> >
> > [1] https://lkml.kernel.org/linux-fsdevel/[email protected]/T/#u
> >
> > Changed v1 => v2:
> > - Added check for S_ISREG() which technically should be there, though
> > it happens not to matter currently.
> >
> > Chandan Rajendra (1):
> > ext4: Enable encryption for subpage-sized blocks
> >
> > Eric Biggers (1):
> > fs/buffer.c: support fscrypt in block_read_full_page()
> >
> > Documentation/filesystems/fscrypt.rst | 4 +--
> > fs/buffer.c | 48 ++++++++++++++++++++++++---
> > fs/ext4/super.c | 7 ----
> > 3 files changed, 45 insertions(+), 14 deletions(-)
> >
>
> Any more comments on this?
>
> Ted, are you interested in taking this through the ext4 tree for 5.5?
>
Ping.