Messages in this thread | | | Subject | Re: [fuse-devel] [PATCH 01/25] VFS: move attr_kill logic from notify_change into helper function | From | Trond Myklebust <> | Date | Mon, 06 Aug 2007 17:23:39 -0400 |
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On Mon, 2007-08-06 at 21:37 +0200, Miklos Szeredi wrote: > > > Your patch is changing the API in a very unsafe way, since there will > > > be no error or warning on an unconverted fs. And that could lead to > > > security holes. > > > > > > If we would rename the setattr method to setattr_new as well as > > > changing it's behavior, that would be fine. But I guess we do not > > > want to do that. > > > > Which "unconverted fses"? If we're talking out of tree stuff, then too > > bad: it is _their_ responsibility to keep up with kernel changes. > > It is usually a good idea to not change the semantics of an API in a > backward incompatible way without changing the syntax as well.
We're taking two setattr flags ATTR_KILL_SGID, and ATTR_KILL_SUID which have existed for several years in the VFS, and making them visible to the filesystems. Out-of-tree filesystems that care can check for them in a completely backward compatible way: you don't even need to add a #define.
> This is true regardless of whether we care about out-of-tree code or > not (and we should care to some degree). And especially true if the > change in question is security sensitive.
It is not true "regardless": the in-tree code is being converted. Out-of-tree code is the only "problem" here, and their only problem is that they may have to add support for the new flags if they also support suid/sgid mode bits.
Are you advocating reserving a new filesystem bit every time we need to add an attribute flag?
Trond
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