| Message ID | 20231114153321.1716028-6-amir73il@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Tidy up file permission hooks | expand |
On Tue, Nov 14, 2023 at 05:33:11PM +0200, Amir Goldstein wrote: > All the callers of ->splice_write(), (e.g. do_splice_direct() and > do_splice()) already check rw_verify_area() for the entire range > and perform all the other checks that are in vfs_write_iter(). > > Create a helper do_iter_writev(), that performs the write without the > checks and use it in iter_file_splice_write() to avoid the redundant > rw_verify_area() checks. > > This is needed for fanotify "pre content" events. > > Suggested-by: Jan Kara <jack@suse.cz> > Signed-off-by: Amir Goldstein <amir73il@gmail.com> > --- If you resend anyway, for the low-level splice helpers specifically it would be nice to add a comment that mentions that the caller is expected to perform basic rw checks.
On Tue, Nov 21, 2023 at 4:56 PM Christian Brauner <brauner@kernel.org> wrote: > > On Tue, Nov 14, 2023 at 05:33:11PM +0200, Amir Goldstein wrote: > > All the callers of ->splice_write(), (e.g. do_splice_direct() and > > do_splice()) already check rw_verify_area() for the entire range > > and perform all the other checks that are in vfs_write_iter(). > > > > Create a helper do_iter_writev(), that performs the write without the > > checks and use it in iter_file_splice_write() to avoid the redundant > > rw_verify_area() checks. > > > > This is needed for fanotify "pre content" events. > > > > Suggested-by: Jan Kara <jack@suse.cz> > > Signed-off-by: Amir Goldstein <amir73il@gmail.com> > > --- > > If you resend anyway, for the low-level splice helpers specifically it > would be nice to add a comment that mentions that the caller is expected > to perform basic rw checks. Will do. Thanks, Amir.
diff --git a/fs/internal.h b/fs/internal.h index 58e43341aebf..c114b85e27a7 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -298,7 +298,13 @@ static inline ssize_t do_get_acl(struct mnt_idmap *idmap, } #endif -ssize_t __kernel_write_iter(struct file *file, struct iov_iter *from, loff_t *pos); +/* + * fs/read_write.c + */ +ssize_t __kernel_write_iter(struct file *file, struct iov_iter *from, + loff_t *pos); +ssize_t do_iter_writev(struct file *file, struct iov_iter *iter, loff_t *ppos, + rwf_t flags); /* * fs/attr.c diff --git a/fs/read_write.c b/fs/read_write.c index 4771701c896b..590ab228fa98 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -739,6 +739,13 @@ static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter, return ret; } +ssize_t do_iter_writev(struct file *filp, struct iov_iter *iter, loff_t *ppos, + rwf_t flags) +{ + return do_iter_readv_writev(filp, iter, ppos, WRITE, flags); +} + + /* Do it by hand, with file-ops */ static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter, loff_t *ppos, int type, rwf_t flags) diff --git a/fs/splice.c b/fs/splice.c index d4fdd44c0b32..decbace5d812 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -673,10 +673,13 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, .u.file = out, }; int nbufs = pipe->max_usage; - struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec), - GFP_KERNEL); + struct bio_vec *array; ssize_t ret; + if (!out->f_op->write_iter) + return -EINVAL; + + array = kcalloc(nbufs, sizeof(struct bio_vec), GFP_KERNEL); if (unlikely(!array)) return -ENOMEM; @@ -733,7 +736,7 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, } iov_iter_bvec(&from, ITER_SOURCE, array, n, sd.total_len - left); - ret = vfs_iter_write(out, &from, &sd.pos, 0); + ret = do_iter_writev(out, &from, &sd.pos, 0); if (ret <= 0) break;
All the callers of ->splice_write(), (e.g. do_splice_direct() and do_splice()) already check rw_verify_area() for the entire range and perform all the other checks that are in vfs_write_iter(). Create a helper do_iter_writev(), that performs the write without the checks and use it in iter_file_splice_write() to avoid the redundant rw_verify_area() checks. This is needed for fanotify "pre content" events. Suggested-by: Jan Kara <jack@suse.cz> Signed-off-by: Amir Goldstein <amir73il@gmail.com> --- fs/internal.h | 8 +++++++- fs/read_write.c | 7 +++++++ fs/splice.c | 9 ++++++--- 3 files changed, 20 insertions(+), 4 deletions(-)