linux-ext4 - [PATCH v2] vfs: only allow SETFLAGS to set DAX flag on files and dirs

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Date:   Mon, 19 Jul 2021 10:38:34 +0800
From:   Jeffle Xu <jefflexu@...ux.alibaba.com>
To:     viro@...iv.linux.org.uk
Cc:     linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
        djwong@...nel.org
Subject: [PATCH v2] vfs: only allow SETFLAGS to set DAX flag on files and dirs

This is similar to commit dbc77f31e58b ("vfs: only allow FSSETXATTR to
set DAX flag on files and dirs").

Though the underlying filesystems may have filtered invalid flags, e.g.,
ext4_mask_flags() called in ext4_fileattr_set(), also check it in VFS
layer.

Signed-off-by: Jeffle Xu <jefflexu@...ux.alibaba.com>
---
changes since v1:
- add separate parentheses surrounding flag tests
---
 fs/ioctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ioctl.c b/fs/ioctl.c
index 1e2204fa9963..90cfaa4db03a 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -835,7 +835,7 @@ static int fileattr_set_prepare(struct inode *inode,
 	 * It is only valid to set the DAX flag on regular files and
 	 * directories on filesystems.
 	 */
-	if ((fa->fsx_xflags & FS_XFLAG_DAX) &&
+	if (((fa->fsx_xflags & FS_XFLAG_DAX) || (fa->flags & FS_DAX_FL)) &&
 	    !(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)))
 		return -EINVAL;
 
-- 
2.27.0