Messages in this thread | | | Subject | FUSE: regression when clearing setuid bits on chown | From | Jeff Layton <> | Date | Mon, 05 Dec 2016 13:21:15 -0500 |
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Hi Miklos,
I think we've found a "regression" that has crept in due to this patch:
commit a09f99eddef44035ec764075a37bace8181bec38 Author: Miklos Szeredi <mszeredi@redhat.com> Date: Sat Oct 1 07:32:32 2016 +0200
fuse: fix killing s[ug]id in setattr Basically, the pjdfstests set the ownership of a file to 06555, and then chowns it (as root) to a new uid/gid. Prior to the patch above, fuse would send down a setattr with both the uid/gid change and a new mode. Now, it just sends down the uid/gid change.
Technically this is NOTABUG, since POSIX doesn't _require_ that we clear these bits for a privileged process, but Linux (wisely) has done that and I think we don't want to change that behavior here.
So, the issue I think is the use of should_remove_suid, which will always return 0 when the process has CAP_FSETID. That's appropriate (I think) for write/truncate, but not chown, where we want to ignore that.
Thoughts on the right fix here? A simple fix would be to add an "override" bool to should_remove_suid, but maybe there's some more elegant way to do it?
-- Jeff Layton <jlayton@redhat.com>
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