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Re: [PATCH] check for invalid flags in xfs_attrlist_by_handle

To: Timothy Shimmin <tes@xxxxxxx>
Subject: Re: [PATCH] check for invalid flags in xfs_attrlist_by_handle
From: Christoph Hellwig <hch@xxxxxx>
Date: Mon, 23 Jun 2008 13:39:46 +0200
Cc: xfs@xxxxxxxxxxx
In-reply-to: <485B431F.2070905@xxxxxxx>
References: <20080531075829.GA5424@xxxxxx> <485B431F.2070905@xxxxxxx>
Sender: xfs-bounce@xxxxxxxxxxx
User-agent: Mutt/1.3.28i
On Fri, Jun 20, 2008 at 03:41:51PM +1000, Timothy Shimmin wrote:
> Fair enough.
> Actually, I think we only use ATTR_ROOT and ATTR_SECURE for the
> namespace flags.
> So you could probably use: XFS_ATTR_NSP_ARGS
> xfs_attr_leaf.h:#define XFS_ATTR_NSP_ARGS_MASK         (ATTR_ROOT | 
> ATTR_SECURE)
> xfs_attr_leaf.h:#define XFS_ATTR_NSP_ARGS(flags) ((flags) & 
> XFS_ATTR_NSP_ARGS_MASK)
> and something like:
> 
> if (!XFS_ATTR_NSP_ARGS(al_hreq.flags))
>          return -XFS_ERROR(EINVAL);

Actually a zero flags is of course valid too.

So the check should be & ~(ATTR_ROOT | ATTR_SECURE).  I could use
XFS_ATTR_NSP_ARGS_MASK but that would pull in not just xfs_attr_leaf.h
but also xfs_da_btree.h and that needs even more headers..

So I propose this simple version:


Index: linux-2.6-xfs/fs/xfs/linux-2.6/xfs_ioctl.c
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/linux-2.6/xfs_ioctl.c     2008-06-20 
08:17:13.000000000 +0200
+++ linux-2.6-xfs/fs/xfs/linux-2.6/xfs_ioctl.c  2008-06-23 13:38:17.000000000 
+0200
@@ -470,6 +470,12 @@ xfs_attrlist_by_handle(
        if (al_hreq.buflen > XATTR_LIST_MAX)
                return -XFS_ERROR(EINVAL);
 
+       /*
+        * Reject flags, only allow namespaces.
+        */
+       if (al_hreq.flags & ~(ATTR_ROOT | ATTR_SECURE))
+               return -XFS_ERROR(EINVAL);
+
        error = xfs_vget_fsop_handlereq(mp, parinode, &al_hreq.hreq, &inode);
        if (error)
                goto out;



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