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Merge 881b568756 ("Merge tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt") into android-mainline

Browse Source 
Steps on the way to 5.18-rc1

Resolves conflicts in:
	fs/crypto/inline_crypt.c
	fs/ext4/inode.c

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I9e21246dffb9d7cc6a713fe9820ec93bdabe0f6b
This commit is contained in:
Greg Kroah-Hartman
2022-03-30 14:06:56 +02:00
parent 2c7316efff 881b568756
commit bc3c078603
3 changed files with 54 additions and 16 deletions
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25
Documentation/filesystems/fscrypt.rst
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@@ -1047,8 +1047,8 @@ astute users may notice some differences in behavior:
may be used to overwrite the source files but isn't guaranteed to be
effective on all filesystems and storage devices.
- Direct I/O is not supported on encrypted files. Attempts to use
direct I/O on such files will fall back to buffered I/O.
- Direct I/O is supported on encrypted files only under some
circumstances. For details, see `Direct I/O support`_.
- The fallocate operations FALLOC_FL_COLLAPSE_RANGE and
FALLOC_FL_INSERT_RANGE are not supported on encrypted files and will
@@ -1179,6 +1179,27 @@ Inline encryption doesn't affect the ciphertext or other aspects of
the on-disk format, so users may freely switch back and forth between
using "inlinecrypt" and not using "inlinecrypt".
Direct I/O support
==================
For direct I/O on an encrypted file to work, the following conditions
must be met (in addition to the conditions for direct I/O on an
unencrypted file):
* The file must be using inline encryption. Usually this means that
the filesystem must be mounted with ``-o inlinecrypt`` and inline
encryption hardware must be present. However, a software fallback
is also available. For details, see `Inline encryption support`_.
* The I/O request must be fully aligned to the filesystem block size.
This means that the file position the I/O is targeting, the lengths
of all I/O segments, and the memory addresses of all I/O buffers
must be multiples of this value. Note that the filesystem block
size may be greater than the logical block size of the block device.
If either of the above conditions is not met, then direct I/O on the
encrypted file will fall back to buffered I/O.
Implementation details
======================

42
fs/crypto/inline_crypt.c
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@@ -380,6 +380,10 @@ EXPORT_SYMBOL_GPL(fscrypt_set_bio_crypt_ctx_bh);
*
* fscrypt_set_bio_crypt_ctx() must have already been called on the bio.
*
* This function isn't required in cases where crypto-mergeability is ensured in
* another way, such as I/O targeting only a single file (and thus a single key)
* combined with fscrypt_limit_io_blocks() to ensure DUN contiguity.
*
* This function also returns false if the next part of the I/O would need to
* have a different value for the bi_skip_dm_default_key flag.
*
@@ -437,12 +441,15 @@ bool fscrypt_mergeable_bio_bh(struct bio *bio,
EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio_bh);
/**
* fscrypt_dio_supported() - check whether a direct I/O request is unsupported
* due to encryption constraints
* fscrypt_dio_supported() - check whether a DIO (direct I/O) request is
* supported as far as encryption is concerned
* @iocb: the file and position the I/O is targeting
* @iter: the I/O data segment(s)
*
* Return: true if direct I/O is supported
* Return: %true if there are no encryption constraints that prevent DIO from
* being supported; %false if DIO is unsupported. (Note that in the
* %true case, the filesystem might have other, non-encryption-related
* constraints that prevent DIO from actually being supported.)
*/
bool fscrypt_dio_supported(struct kiocb *iocb, struct iov_iter *iter)
{
@@ -453,13 +460,22 @@ bool fscrypt_dio_supported(struct kiocb *iocb, struct iov_iter *iter)
if (!fscrypt_needs_contents_encryption(inode))
return true;
/* We only support direct I/O with inline crypto, not fs-layer crypto */
/* We only support DIO with inline crypto, not fs-layer crypto. */
if (!fscrypt_inode_uses_inline_crypto(inode))
return false;
/*
* Since the granularity of encryption is filesystem blocks, the I/O
* must be block aligned -- not just disk sector aligned.
* Since the granularity of encryption is filesystem blocks, the file
* position and total I/O length must be aligned to the filesystem block
* size -- not just to the block device's logical block size as is
* traditionally the case for DIO on many filesystems.
*
* We require that the user-provided memory buffers be filesystem block
* aligned too. It is simpler to have a single alignment value required
* for all properties of the I/O, as is normally the case for DIO.
* Also, allowing less aligned buffers would imply that data units could
* cross bvecs, which would greatly complicate the I/O stack, which
* assumes that bios can be split at any bvec boundary.
*/
if (!IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(iter), blocksize))
return false;
@@ -472,24 +488,25 @@ EXPORT_SYMBOL_GPL(fscrypt_dio_supported);
* fscrypt_limit_io_blocks() - limit I/O blocks to avoid discontiguous DUNs
* @inode: the file on which I/O is being done
* @lblk: the block at which the I/O is being started from
* @nr_blocks: the number of blocks we want to submit starting at @pos
* @nr_blocks: the number of blocks we want to submit starting at @lblk
*
* Determine the limit to the number of blocks that can be submitted in the bio
* targeting @pos without causing a data unit number (DUN) discontinuity.
* Determine the limit to the number of blocks that can be submitted in a bio
* targeting @lblk without causing a data unit number (DUN) discontiguity.
*
* This is normally just @nr_blocks, as normally the DUNs just increment along
* with the logical blocks. (Or the file is not encrypted.)
*
* In rare cases, fscrypt can be using an IV generation method that allows the
* DUN to wrap around within logically continuous blocks, and that wraparound
* DUN to wrap around within logically contiguous blocks, and that wraparound
* will occur. If this happens, a value less than @nr_blocks will be returned
* so that the wraparound doesn't occur in the middle of the bio.
* so that the wraparound doesn't occur in the middle of a bio, which would
* cause encryption/decryption to produce wrong results.
*
* Return: the actual number of blocks that can be submitted
*/
u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks)
{
const struct fscrypt_info *ci = inode->i_crypt_info;
const struct fscrypt_info *ci;
u32 dun;
if (!fscrypt_inode_uses_inline_crypto(inode))
@@ -498,6 +515,7 @@ u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks)
if (nr_blocks <= 1)
return nr_blocks;
ci = inode->i_crypt_info;
if (!(fscrypt_policy_flags(&ci->ci_policy) &
FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32))
return nr_blocks;

3
fs/ext4/inode.c
View File

@@ -3409,10 +3409,9 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
if (ret < 0)
return ret;
out:
/*
* When inline encryption is enabled, sometimes I/O to an encrypted file
* has to be broken up to guarantee DUN contiguity. Handle this by
* has to be broken up to guarantee DUN contiguity. Handle this by
* limiting the length of the mapping returned.
*/
map.m_len = fscrypt_limit_io_blocks(inode, map.m_lblk, map.m_len);