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ovl: handle ATTR_KILL*

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commit b99c2d9138 upstream.

Before 4bacc9c923 ("overlayfs: Make f_path...") file->f_path pointed to
the underlying file, hence suid/sgid removal on write worked fine.

After that patch file->f_path pointed to the overlay file, and the file
mode bits weren't copied to overlay_inode->i_mode.  So the suid/sgid
removal simply stopped working.

The fix is to copy the mode bits, but then ovl_setattr() needs to clear
ATTR_MODE to avoid the BUG() in notify_change().  So do this first, then in
the next patch copy the mode.

Reported-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 4bacc9c923 ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
Cc: Eric Schultz <eric@startuperic.com>
Cc: Eric Hameleers <alien@slackware.com>
[backported by Eric Hameleers as seen in https://bugzilla.kernel.org/show_bug.cgi?id=150711]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Miklos Szeredi 2016-07-04 16:49:48 +02:00 committed by Greg Kroah-Hartman
parent 34bf12312b
commit b82c78948a
1 changed files with 3 additions and 0 deletions
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3
fs/overlayfs/inode.c
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@ -63,6 +63,9 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
if (!err) {
upperdentry = ovl_dentry_upper(dentry);
if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
attr->ia_valid &= ~ATTR_MODE;
mutex_lock(&upperdentry->d_inode->i_mutex);
err = notify_change(upperdentry, attr, NULL);
if (!err)