For overlay file open, check IS_APPEND() on real backing inode
inside vfs_open(), because the overlay inode does not have the
S_APPEND flag.
This seems like the wrong place for this check.
Probably better to propagate S_APPEND flag to overlay inode.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/open.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/fs/open.c b/fs/open.c
index baf67cd..8f1754d 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -859,6 +859,15 @@ int vfs_open(const struct path *path, struct file *file,
if (IS_ERR(dentry))
return PTR_ERR(dentry);
+ /* Check append-only open flags also against real inode */
+ if (dentry != path->dentry && IS_APPEND(d_backing_inode(dentry))) {
+ if ((file->f_flags & O_ACCMODE) != O_RDONLY &&
+ !(file->f_flags & O_APPEND))
+ return -EPERM;
+ if (file->f_flags & O_TRUNC)
+ return -EPERM;
+ }
+
file->f_path = *path;
return do_dentry_open(file, d_backing_inode(dentry), NULL, cred);
}
--
2.7.4
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