On Mon, Oct 15, 2018 at 08:19:26PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Create a new VFS helper to handle inode metadata updates when remapping
> into a file. If the operation can possibly alter the file contents, we
> must update the ctime and mtime and remove security privileges, just
> like we do for regular file writes. Wire up ocfs2 to ensure consistent
> behavior.
Subject line doesn't match the actual function name..
> +/* Update inode timestamps and remove security privileges when remapping. */
> +static int generic_remap_file_range_target(struct file *file,
> + unsigned int remap_flags)
> +{
> + int ret;
> +
> + /* If can't alter the file contents, we're done. */
> + if (remap_flags & REMAP_FILE_DEDUP)
> + return 0;
> +
> + /* Update the timestamps, since we can alter file contents. */
> + if (!(file->f_mode & FMODE_NOCMTIME)) {
> + ret = file_update_time(file);
> + if (ret)
> + return ret;
> + }
> +
> + /*
> + * Clear the security bits if the process is not being run by root.
> + * This keeps people from modifying setuid and setgid binaries.
> + */
> + return file_remove_privs(file);
> +}
> +
> /*
> * Check that the two inodes are eligible for cloning, the ranges make
> * sense, and then flush all dirty data. Caller must ensure that the
> @@ -1820,6 +1844,10 @@ int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> if (ret)
> return ret;
>
> + ret = generic_remap_file_range_target(file_out, remap_flags);
> + if (ret)
> + return ret;
> +
Also I find the name still somewhat odd. Why don't we side-step that
issue by moving the code directly into generic_remap_file_range_prep?
Something like this folded in:
diff --git a/fs/read_write.c b/fs/read_write.c
index 37a7d3fe35d8..6de813cf9e63 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1752,30 +1752,6 @@ static int generic_remap_check_len(struct inode *inode_in,
return (remap_flags & REMAP_FILE_DEDUP) ? -EBADE : -EINVAL;
}
-/* Update inode timestamps and remove security privileges when remapping. */
-static int generic_remap_file_range_target(struct file *file,
- unsigned int remap_flags)
-{
- int ret;
-
- /* If can't alter the file contents, we're done. */
- if (remap_flags & REMAP_FILE_DEDUP)
- return 0;
-
- /* Update the timestamps, since we can alter file contents. */
- if (!(file->f_mode & FMODE_NOCMTIME)) {
- ret = file_update_time(file);
- if (ret)
- return ret;
- }
-
- /*
- * Clear the security bits if the process is not being run by root.
- * This keeps people from modifying setuid and setgid binaries.
- */
- return file_remove_privs(file);
-}
-
/*
* Read a page's worth of file data into the page cache. Return the page
* locked.
@@ -1950,9 +1926,25 @@ int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
if (ret)
return ret;
- ret = generic_remap_file_range_target(file_out, remap_flags);
- if (ret)
- return ret;
+ if (!(remap_flags & REMAP_FILE_DEDUP)) {
+ /*
+ * Update the timestamps, since we can alter file contents.
+ */
+ if (!(file_out->f_mode & FMODE_NOCMTIME)) {
+ ret = file_update_time(file_out);
+ if (ret)
+ return ret;
+ }
+
+ /*
+ * Clear the security bits if the process is not being run by
+ * root. This keeps people from modifying setuid and setgid
+ * binaries.
+ */
+ ret = file_remove_privs(file_out);
+ if (ret)
+ return ret;
+ }
return 0;
}
