| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 50/68] ovl: handle ATTR_KILL* | Date | Mon, 8 Aug 2016 21:11:25 +0200 |
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4.4-stable review patch. If anyone has any objections, please let me know.
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From: Miklos Szeredi <mszeredi@redhat.com>
commit b99c2d913810e56682a538c9f2394d76fca808f8 upstream.
Before 4bacc9c9234c ("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: 4bacc9c9234c ("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>
--- fs/overlayfs/inode.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -63,6 +63,9 @@ int ovl_setattr(struct dentry *dentry, s 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)
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