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-rw-r--r--Documentation/filesystems/fscrypt.rst25
-rw-r--r--fs/crypto/crypto.c8
-rw-r--r--fs/crypto/inline_crypt.c93
-rw-r--r--fs/ext4/file.c10
-rw-r--r--fs/ext4/inode.c7
-rw-r--r--fs/f2fs/data.c7
-rw-r--r--fs/f2fs/f2fs.h6
-rw-r--r--fs/iomap/direct-io.c6
-rw-r--r--include/linux/fscrypt.h18
9 files changed, 173 insertions, 7 deletions
diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst
index 4d5d50dca65c..6ccd5efb25b7 100644
--- a/Documentation/filesystems/fscrypt.rst
+++ b/Documentation/filesystems/fscrypt.rst
@@ -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
======================
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 4ef3f714046a..4fcca79f39ae 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -69,6 +69,14 @@ void fscrypt_free_bounce_page(struct page *bounce_page)
}
EXPORT_SYMBOL(fscrypt_free_bounce_page);
+/*
+ * Generate the IV for the given logical block number within the given file.
+ * For filenames encryption, lblk_num == 0.
+ *
+ * Keep this in sync with fscrypt_limit_io_blocks(). fscrypt_limit_io_blocks()
+ * needs to know about any IV generation methods where the low bits of IV don't
+ * simply contain the lblk_num (e.g., IV_INO_LBLK_32).
+ */
void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
const struct fscrypt_info *ci)
{
diff --git a/fs/crypto/inline_crypt.c b/fs/crypto/inline_crypt.c
index c57bebfa48fe..93c2ca858092 100644
--- a/fs/crypto/inline_crypt.c
+++ b/fs/crypto/inline_crypt.c
@@ -17,6 +17,7 @@
#include <linux/buffer_head.h>
#include <linux/sched/mm.h>
#include <linux/slab.h>
+#include <linux/uio.h>
#include "fscrypt_private.h"
@@ -315,6 +316,10 @@ 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.
+ *
* Return: true iff the I/O is mergeable
*/
bool fscrypt_mergeable_bio(struct bio *bio, const struct inode *inode,
@@ -363,3 +368,91 @@ bool fscrypt_mergeable_bio_bh(struct bio *bio,
return fscrypt_mergeable_bio(bio, inode, next_lblk);
}
EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio_bh);
+
+/**
+ * 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 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)
+{
+ const struct inode *inode = file_inode(iocb->ki_filp);
+ const unsigned int blocksize = i_blocksize(inode);
+
+ /* If the file is unencrypted, no veto from us. */
+ if (!fscrypt_needs_contents_encryption(inode))
+ return true;
+
+ /* 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 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;
+
+ return true;
+}
+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 @lblk
+ *
+ * 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 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 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;
+ u32 dun;
+
+ if (!fscrypt_inode_uses_inline_crypto(inode))
+ return 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;
+
+ /* With IV_INO_LBLK_32, the DUN can wrap around from U32_MAX to 0. */
+
+ dun = ci->ci_hashed_ino + lblk;
+
+ return min_t(u64, nr_blocks, (u64)U32_MAX + 1 - dun);
+}
+EXPORT_SYMBOL_GPL(fscrypt_limit_io_blocks);
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 8cc11715518a..8bd66cdc41be 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -36,9 +36,11 @@
#include "acl.h"
#include "truncate.h"
-static bool ext4_dio_supported(struct inode *inode)
+static bool ext4_dio_supported(struct kiocb *iocb, struct iov_iter *iter)
{
- if (IS_ENABLED(CONFIG_FS_ENCRYPTION) && IS_ENCRYPTED(inode))
+ struct inode *inode = file_inode(iocb->ki_filp);
+
+ if (!fscrypt_dio_supported(iocb, iter))
return false;
if (fsverity_active(inode))
return false;
@@ -61,7 +63,7 @@ static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
inode_lock_shared(inode);
}
- if (!ext4_dio_supported(inode)) {
+ if (!ext4_dio_supported(iocb, to)) {
inode_unlock_shared(inode);
/*
* Fallback to buffered I/O if the operation being performed on
@@ -509,7 +511,7 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
}
/* Fallback to buffered I/O if the inode does not support direct I/O. */
- if (!ext4_dio_supported(inode)) {
+ if (!ext4_dio_supported(iocb, from)) {
if (ilock_shared)
inode_unlock_shared(inode);
else
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 01c9e4f743ba..4cf55ef54193 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3409,6 +3409,13 @@ 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
+ * limiting the length of the mapping returned.
+ */
+ map.m_len = fscrypt_limit_io_blocks(inode, map.m_lblk, map.m_len);
+
ext4_set_iomap(inode, iomap, &map, offset, length, flags);
return 0;
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index fc077bce679d..79c9ed74bd8b 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -4032,6 +4032,13 @@ static int f2fs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
iomap->offset = blks_to_bytes(inode, map.m_lblk);
+ /*
+ * When inline encryption is enabled, sometimes I/O to an encrypted file
+ * 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);
+
if (map.m_flags & (F2FS_MAP_MAPPED | F2FS_MAP_UNWRITTEN)) {
iomap->length = blks_to_bytes(inode, map.m_len);
if (map.m_flags & F2FS_MAP_MAPPED) {
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index d51a3ede4b0f..c2c89b03df1e 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -4371,7 +4371,11 @@ static inline bool f2fs_force_buffered_io(struct inode *inode,
struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
int rw = iov_iter_rw(iter);
- if (f2fs_post_read_required(inode))
+ if (!fscrypt_dio_supported(iocb, iter))
+ return true;
+ if (fsverity_active(inode))
+ return true;
+ if (f2fs_compressed_file(inode))
return true;
/* disallow direct IO if any of devices has unaligned blksize */
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index e2ba13645ef2..67cf9c16f80c 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -6,6 +6,7 @@
#include <linux/module.h>
#include <linux/compiler.h>
#include <linux/fs.h>
+#include <linux/fscrypt.h>
#include <linux/pagemap.h>
#include <linux/iomap.h>
#include <linux/backing-dev.h>
@@ -179,11 +180,14 @@ static void iomap_dio_bio_end_io(struct bio *bio)
static void iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio,
loff_t pos, unsigned len)
{
+ struct inode *inode = file_inode(dio->iocb->ki_filp);
struct page *page = ZERO_PAGE(0);
int flags = REQ_SYNC | REQ_IDLE;
struct bio *bio;
bio = bio_alloc(iter->iomap.bdev, 1, REQ_OP_WRITE | flags, GFP_KERNEL);
+ fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits,
+ GFP_KERNEL);
bio->bi_iter.bi_sector = iomap_sector(&iter->iomap, pos);
bio->bi_private = dio;
bio->bi_end_io = iomap_dio_bio_end_io;
@@ -308,6 +312,8 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
}
bio = bio_alloc(iomap->bdev, nr_pages, bio_opf, GFP_KERNEL);
+ fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits,
+ GFP_KERNEL);
bio->bi_iter.bi_sector = iomap_sector(iomap, pos);
bio->bi_write_hint = dio->iocb->ki_hint;
bio->bi_ioprio = dio->iocb->ki_ioprio;
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 91ea9477e9bd..50d92d805bd8 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -714,6 +714,10 @@ bool fscrypt_mergeable_bio(struct bio *bio, const struct inode *inode,
bool fscrypt_mergeable_bio_bh(struct bio *bio,
const struct buffer_head *next_bh);
+bool fscrypt_dio_supported(struct kiocb *iocb, struct iov_iter *iter);
+
+u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks);
+
#else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */
static inline bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode)
@@ -742,6 +746,20 @@ static inline bool fscrypt_mergeable_bio_bh(struct bio *bio,
{
return true;
}
+
+static inline bool fscrypt_dio_supported(struct kiocb *iocb,
+ struct iov_iter *iter)
+{
+ const struct inode *inode = file_inode(iocb->ki_filp);
+
+ return !fscrypt_needs_contents_encryption(inode);
+}
+
+static inline u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk,
+ u64 nr_blocks)
+{
+ return nr_blocks;
+}
#endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */
/**