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[v2,0/2] ext4: support encryption with blocksize != PAGE_SIZE

Message ID 20191023033312.361355-1-ebiggers@kernel.org (mailing list archive)
Headers show
Series ext4: support encryption with blocksize != PAGE_SIZE | expand

Message

Eric Biggers Oct. 23, 2019, 3:33 a.m. UTC
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/20190910155115.28550-1-chandan@linux.ibm.com/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(-)

Comments

Chandan Rajendra Oct. 25, 2019, 1:30 p.m. UTC | #1
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 <chandan@linux.ibm.com>
Eric Biggers Nov. 6, 2019, 9:54 p.m. UTC | #2
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/20190910155115.28550-1-chandan@linux.ibm.com/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
Eric Biggers Nov. 11, 2019, 8:28 p.m. UTC | #3
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/20190910155115.28550-1-chandan@linux.ibm.com/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.