From feebea75bdf499aefd11d0df7b02d384a9f92fc1 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Wed, 22 Nov 2023 14:27:02 +0200 Subject: splice: move permission hook out of splice_direct_to_actor() vfs_splice_read() has a permission hook inside rw_verify_area() and it is called from do_splice_direct() -> splice_direct_to_actor(). The callers of do_splice_direct() (e.g. vfs_copy_file_range()) already call rw_verify_area() for the entire range, but the other caller of splice_direct_to_actor() (nfsd) does not. Add the rw_verify_area() checks in nfsd_splice_read() and use a variant of vfs_splice_read() without rw_verify_area() check in splice_direct_to_actor() to avoid the redundant rw_verify_area() checks. This is needed for fanotify "pre content" events. Acked-by: Chuck Lever Reviewed-by: Josef Bacik Signed-off-by: Amir Goldstein Link: https://lore.kernel.org/r/20231122122715.2561213-4-amir73il@gmail.com Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Signed-off-by: Christian Brauner --- fs/splice.c | 58 +++++++++++++++++++++++++++++++++++----------------------- 1 file changed, 35 insertions(+), 23 deletions(-) (limited to 'fs/splice.c') diff --git a/fs/splice.c b/fs/splice.c index 6e917db6f49a..6fc2c27e9520 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -944,27 +944,15 @@ static void do_splice_eof(struct splice_desc *sd) sd->splice_eof(sd); } -/** - * vfs_splice_read - Read data from a file and splice it into a pipe - * @in: File to splice from - * @ppos: Input file offset - * @pipe: Pipe to splice to - * @len: Number of bytes to splice - * @flags: Splice modifier flags (SPLICE_F_*) - * - * Splice the requested amount of data from the input file to the pipe. This - * is synchronous as the caller must hold the pipe lock across the entire - * operation. - * - * If successful, it returns the amount of data spliced, 0 if it hit the EOF or - * a hole and a negative error code otherwise. +/* + * Callers already called rw_verify_area() on the entire range. + * No need to call it for sub ranges. */ -long vfs_splice_read(struct file *in, loff_t *ppos, - struct pipe_inode_info *pipe, size_t len, - unsigned int flags) +static long do_splice_read(struct file *in, loff_t *ppos, + struct pipe_inode_info *pipe, size_t len, + unsigned int flags) { unsigned int p_space; - int ret; if (unlikely(!(in->f_mode & FMODE_READ))) return -EBADF; @@ -975,10 +963,6 @@ long vfs_splice_read(struct file *in, loff_t *ppos, p_space = pipe->max_usage - pipe_occupancy(pipe->head, pipe->tail); len = min_t(size_t, len, p_space << PAGE_SHIFT); - ret = rw_verify_area(READ, in, ppos, len); - if (unlikely(ret < 0)) - return ret; - if (unlikely(len > MAX_RW_COUNT)) len = MAX_RW_COUNT; @@ -992,6 +976,34 @@ long vfs_splice_read(struct file *in, loff_t *ppos, return copy_splice_read(in, ppos, pipe, len, flags); return in->f_op->splice_read(in, ppos, pipe, len, flags); } + +/** + * vfs_splice_read - Read data from a file and splice it into a pipe + * @in: File to splice from + * @ppos: Input file offset + * @pipe: Pipe to splice to + * @len: Number of bytes to splice + * @flags: Splice modifier flags (SPLICE_F_*) + * + * Splice the requested amount of data from the input file to the pipe. This + * is synchronous as the caller must hold the pipe lock across the entire + * operation. + * + * If successful, it returns the amount of data spliced, 0 if it hit the EOF or + * a hole and a negative error code otherwise. + */ +long vfs_splice_read(struct file *in, loff_t *ppos, + struct pipe_inode_info *pipe, size_t len, + unsigned int flags) +{ + int ret; + + ret = rw_verify_area(READ, in, ppos, len); + if (unlikely(ret < 0)) + return ret; + + return do_splice_read(in, ppos, pipe, len, flags); +} EXPORT_SYMBOL_GPL(vfs_splice_read); /** @@ -1066,7 +1078,7 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, size_t read_len; loff_t pos = sd->pos, prev_pos = pos; - ret = vfs_splice_read(in, &pos, pipe, len, flags); + ret = do_splice_read(in, &pos, pipe, len, flags); if (unlikely(ret <= 0)) goto read_failure; -- cgit v1.2.3