| Message ID | 20200720233739.824943-2-satyat@google.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | add support for direct I/O with fscrypt using blk-crypto | expand |
On 07/20, Satya Tangirala wrote: > From: Eric Biggers <ebiggers@google.com> > > Introduce fscrypt_dio_supported() to check whether a direct I/O request > is unsupported due to encryption constraints. > > Also introduce fscrypt_limit_io_pages() to limit how many pages can be > added to a bio being prepared for direct I/O. This is needed for the > iomap direct I/O implementation to avoid DUN wraparound in the middle of > a bio (which is possible with the IV_INO_LBLK_32 IV generation method). > Elsewhere fscrypt_mergeable_bio() is used for this, but iomap operates > on logical ranges directly and doesn't have a chance to call > fscrypt_mergeable_bio() on every block or page. So we need this function > which limits a logical range in one go. > > Signed-off-by: Eric Biggers <ebiggers@google.com> > Co-developed-by: Satya Tangirala <satyat@google.com> > Signed-off-by: Satya Tangirala <satyat@google.com> Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org> > --- > fs/crypto/crypto.c | 8 ++++ > fs/crypto/inline_crypt.c | 82 ++++++++++++++++++++++++++++++++++++++++ > include/linux/fscrypt.h | 19 ++++++++++ > 3 files changed, 109 insertions(+) > > diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c > index a52cf32733ab..fb34364360b3 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_pages(). fscrypt_limit_io_pages() > + * 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 d7aecadf33c1..578739712e00 100644 > --- a/fs/crypto/inline_crypt.c > +++ b/fs/crypto/inline_crypt.c > @@ -16,6 +16,7 @@ > #include <linux/blkdev.h> > #include <linux/buffer_head.h> > #include <linux/sched/mm.h> > +#include <linux/uio.h> > > #include "fscrypt_private.h" > > @@ -362,3 +363,84 @@ 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 direct I/O request is unsupported > + * due to encryption constraints > + * @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 > + */ > +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 direct I/O 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. > + */ > + if (!IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(iter), blocksize)) > + return false; > + > + return true; > +} > +EXPORT_SYMBOL_GPL(fscrypt_dio_supported); > + > +/** > + * fscrypt_limit_io_pages() - limit I/O pages to avoid discontiguous DUNs > + * @inode: the file on which I/O is being done > + * @pos: the file position (in bytes) at which the I/O is being done > + * @nr_pages: the number of pages we want to submit starting at @pos > + * > + * Determine the limit to the number of pages that can be submitted in the bio > + * targeting @pos without causing a data unit number (DUN) discontinuity. > + * > + * This is normally just @nr_pages, 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 > + * will occur. If this happens, a value less than @nr_pages will be returned so > + * that the wraparound doesn't occur in the middle of the bio. Note that we > + * only support block_size == PAGE_SIZE (and page-aligned DIO) in such cases. > + * > + * Return: the actual number of pages that can be submitted > + */ > +int fscrypt_limit_io_pages(const struct inode *inode, loff_t pos, int nr_pages) > +{ > + const struct fscrypt_info *ci = inode->i_crypt_info; > + u32 dun; > + > + if (!fscrypt_inode_uses_inline_crypto(inode)) > + return nr_pages; > + > + if (nr_pages <= 1) > + return nr_pages; > + > + if (!(fscrypt_policy_flags(&ci->ci_policy) & > + FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) > + return nr_pages; > + > + /* > + * fscrypt_select_encryption_impl() ensures that block_size == PAGE_SIZE > + * when using FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32. > + */ > + if (WARN_ON_ONCE(i_blocksize(inode) != PAGE_SIZE)) > + return 1; > + > + /* With IV_INO_LBLK_32, the DUN can wrap around from U32_MAX to 0. */ > + > + dun = ci->ci_hashed_ino + (pos >> inode->i_blkbits); > + > + return min_t(u64, nr_pages, (u64)U32_MAX + 1 - dun); > +} > diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h > index bb257411365f..c205c214b35e 100644 > --- a/include/linux/fscrypt.h > +++ b/include/linux/fscrypt.h > @@ -559,6 +559,11 @@ 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); > + > +int fscrypt_limit_io_pages(const struct inode *inode, loff_t pos, > + int nr_pages); > + > #else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ > > static inline bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode) > @@ -587,6 +592,20 @@ 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 int fscrypt_limit_io_pages(const struct inode *inode, loff_t pos, > + int nr_pages) > +{ > + return nr_pages; > +} > #endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ > > /** > -- > 2.28.0.rc0.105.gf9edc3c819-goog
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c index a52cf32733ab..fb34364360b3 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_pages(). fscrypt_limit_io_pages() + * 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 d7aecadf33c1..578739712e00 100644 --- a/fs/crypto/inline_crypt.c +++ b/fs/crypto/inline_crypt.c @@ -16,6 +16,7 @@ #include <linux/blkdev.h> #include <linux/buffer_head.h> #include <linux/sched/mm.h> +#include <linux/uio.h> #include "fscrypt_private.h" @@ -362,3 +363,84 @@ 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 direct I/O request is unsupported + * due to encryption constraints + * @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 + */ +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 direct I/O 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. + */ + if (!IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(iter), blocksize)) + return false; + + return true; +} +EXPORT_SYMBOL_GPL(fscrypt_dio_supported); + +/** + * fscrypt_limit_io_pages() - limit I/O pages to avoid discontiguous DUNs + * @inode: the file on which I/O is being done + * @pos: the file position (in bytes) at which the I/O is being done + * @nr_pages: the number of pages we want to submit starting at @pos + * + * Determine the limit to the number of pages that can be submitted in the bio + * targeting @pos without causing a data unit number (DUN) discontinuity. + * + * This is normally just @nr_pages, 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 + * will occur. If this happens, a value less than @nr_pages will be returned so + * that the wraparound doesn't occur in the middle of the bio. Note that we + * only support block_size == PAGE_SIZE (and page-aligned DIO) in such cases. + * + * Return: the actual number of pages that can be submitted + */ +int fscrypt_limit_io_pages(const struct inode *inode, loff_t pos, int nr_pages) +{ + const struct fscrypt_info *ci = inode->i_crypt_info; + u32 dun; + + if (!fscrypt_inode_uses_inline_crypto(inode)) + return nr_pages; + + if (nr_pages <= 1) + return nr_pages; + + if (!(fscrypt_policy_flags(&ci->ci_policy) & + FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) + return nr_pages; + + /* + * fscrypt_select_encryption_impl() ensures that block_size == PAGE_SIZE + * when using FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32. + */ + if (WARN_ON_ONCE(i_blocksize(inode) != PAGE_SIZE)) + return 1; + + /* With IV_INO_LBLK_32, the DUN can wrap around from U32_MAX to 0. */ + + dun = ci->ci_hashed_ino + (pos >> inode->i_blkbits); + + return min_t(u64, nr_pages, (u64)U32_MAX + 1 - dun); +} diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index bb257411365f..c205c214b35e 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -559,6 +559,11 @@ 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); + +int fscrypt_limit_io_pages(const struct inode *inode, loff_t pos, + int nr_pages); + #else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ static inline bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode) @@ -587,6 +592,20 @@ 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 int fscrypt_limit_io_pages(const struct inode *inode, loff_t pos, + int nr_pages) +{ + return nr_pages; +} #endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ /**