From: Miklos Szeredi <mszeredi@xxxxxxxxxx>
commit 05acefb4872dae89e772729efb194af754c877e8 upstream.
Call inode_permission() on real inode before opening regular file on one of
the underlying layers.
In some cases ovl_permission() already checks access to an underlying file,
but it misses the metacopy case, and possibly other ones as well.
Removing the redundant permission check from ovl_permission() should be
considered later.
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Signed-off-by: Hugo SIMELIERE <hsimeliere.opensource@xxxxxxxxxxx>
---
fs/overlayfs/file.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 73c3e2c21edb..24a83ed9829a 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -34,10 +34,22 @@ static struct file *ovl_open_realfile(const struct file *file,
struct file *realfile;
const struct cred *old_cred;
int flags = file->f_flags | OVL_OPEN_FLAGS;
+ int acc_mode = ACC_MODE(flags);
+ int err;
+
+ if (flags & O_APPEND)
+ acc_mode |= MAY_APPEND;
old_cred = ovl_override_creds(inode->i_sb);
- realfile = open_with_fake_path(&file->f_path, flags, realinode,
- current_cred());
+ err = inode_permission(realinode, MAY_OPEN | acc_mode);
+ if (err) {
+ realfile = ERR_PTR(err);
+ } else if (!inode_owner_or_capable(realinode)) {
+ realfile = ERR_PTR(-EPERM);
+ } else {
+ realfile = open_with_fake_path(&file->f_path, flags, realinode,
+ current_cred());
+ }
revert_creds(old_cred);
pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",
--
2.43.0
